Tibiofemoral joint contact area and pressure after single- and double-bundle anterior cruciate ligament reconstruction.

PubMed

Morimoto, Yusuke; Ferretti, Mario; Ekdahl, Max; Smolinski, Patrick; Fu, Freddie H

2009-01-01

The purpose of this study was to compare the tibiofemoral contact area and pressure after single-bundle (SB) and double-bundle (DB) anterior cruciate ligament (ACL) reconstruction by use of 2 femoral and 2 tibial tunnels in intact cadaveric knees. Tibiofemoral contact area and mean and maximum pressures were measured by pressure-sensitive film (Fujifilm, Valhalla, NY) inserted between the tibia and femur. The knee was subjected to a 1,000-N axial load by use of a uniaxial testing machine at 0 degrees , 15 degrees , 30 degrees , and 45 degrees of flexion. Three conditions were evaluated: (1) intact ACL, (2) SB ACL reconstruction (n = 10 knees), and (3) DB ACL reconstruction (n = 9 knees). When compared with the intact knee, DB ACL reconstruction showed no significant difference in tibiofemoral contact area and mean and maximum pressures. SB ACL reconstruction had a significantly smaller contact area on the lateral and medial tibiofemoral joints at 30 degrees and 15 degrees of flexion. SB ACL reconstruction also had significantly higher mean pressures at 15 degrees of flexion on the medial tibiofemoral joint and at 0 degrees and 15 degrees of flexion on the lateral tibiofemoral joint, as well as significantly higher maximum pressures at 15 degrees of flexion on the lateral tibiofemoral joint. SB ACL reconstruction resulted in a significantly smaller tibiofemoral contact area and higher pressures. DB ACL more closely restores the normal contact area and pressure mainly at low flexion angles. Our findings suggest that the changes in the contact area and pressures after SB ACL reconstruction may be one of the causes of osteoarthritis on long-term follow-up. DB ACL reconstruction may reduce the incidence of osteoarthritis by closely restoring contact area and pressure.

Femoral tunnel placement in single-bundle anterior cruciate ligament reconstruction: a cadaveric study relating transtibial lateralized femoral tunnel position to the anteromedial and posterolateral bundle femoral origins of the anterior cruciate ligament.

PubMed

Rue, John-Paul H; Ghodadra, Neil; Bach, Bernard R

2008-01-01

There is controversy regarding the necessity of reconstructing both the posterolateral and anteromedial bundles of the anterior cruciate ligament. A laterally oriented transtibial drilled femoral tunnel replaces portions of the femoral footprints of the anteromedial and posterolateral bundles of the anterior cruciate ligament. Descriptive laboratory study. Footprints of the anteromedial and posterolateral bundles of the anterior cruciate ligament were preserved on 7 matched pairs (5 female, 2 male) of fresh-frozen human cadaveric femurs (14 femurs total). Each femur was anatomically oriented and secured in a custom size-appropriate, side-matched replica tibia model to simulate transtibial retrograde drilling of a 10-mm femoral tunnel in each specimen. The relationship of the tunnel relative to footprints of both bundles of the anterior cruciate ligament was recorded using a Microscribe MX digitizer. The angle of the femoral tunnel relative to the vertical 12-o'clock position was recorded for all 14 specimens; only 10 specimens were used for footprint measurements. On average, the 10-mm femoral tunnel overlapped 50% of the anteromedial bundle (range, 2%-83%) and 51% of the posterolateral bundle (range, 16%-97%). The footprint of the anteromedial bundle occupied 32% (range, 3%-49%) of the area of the tunnel; the footprint of the posterolateral bundle contributed 26% (range, 7%-41%). The remainder of the area of the 10-mm tunnel did not overlap with the anterior cruciate ligament footprint. The mean absolute angle of the femoral tunnel as measured directly on the specimen was 48 degrees (range, 42 degrees-53 degrees) from vertical, corresponding to approximately a 10:30 clock face position on a right knee. Anterior cruciate ligament reconstruction using a laterally oriented transtibial drilled femoral tunnel incorporates portions of the anteromedial and posterolateral bundle origins of the native anterior cruciate ligament. A laterally oriented transtibial drilled femoral tunnel placed at the 10:30 position (1:30 for left knees) reconstructs portions of the anteromedial and posterolateral bundles of the anterior cruciate ligament.

Structure and Growth of Quasi One-Dimensional YSi2 Nanophases on Si(100)

PubMed Central

Iancu, V.; Kent, P.R.C.; Hus, S.; Hu, H.; Zeng, C.G.; Weitering, H.H.

2013-01-01

Quasi one-dimensional YSi2 nanostructures are formed via self-assembly on the Si(100) surface. These epitaxial nanowires are metastable and their formation strongly depends on the growth parameters. Here, we explore the various stages of yttrium silicide formation over a range of metal coverages and growth temperatures, and establish a rudimentary phase diagram for these novel and often coexisting nanophases. In addition to previously identified stoichiometric wires, we identify several new nanowire systems. These nanowires exhibit a variety of surface reconstructions, which sometimes coexist on a single wire. From a comparison of scanning tunneling microcopy images, tunneling spectra, and first-principles density functional theory calculations, we determine that these surface reconstructions arise from local orderings of yttrium vacancies. Nanowires often agglomerate into nanowire bundles, the thinnest of which are formed by single wire pairs. The calculations show that such bundles are energetically favored compared to well-separated single wires. Thicker bundles are formed at slightly higher temperature. They extend over several microns, forming a robust network of conducting wires that could possibly be employed in nanodevice applications. PMID:23221350

Comparison of in situ forces and knee kinematics in anteromedial and high anteromedial bundle augmentation for partially ruptured anterior cruciate ligament.

PubMed

Xu, Yan; Liu, Jianyu; Kramer, Scott; Martins, Cesar; Kato, Yuki; Linde-Rosen, Monica; Smolinski, Patrick; Fu, Freddie H

2011-02-01

High tunnel placement is common in single- and double-bundle anterior cruciate ligament (ACL) reconstructions. Similar nonanatomic tunnel placement may also occur in ACL augmentation surgery. In this study, in situ forces and knee kinematics were compared between nonanatomic high anteromedial (AM) and anatomic AM augmentation in a knee with isolated AM bundle injury. Controlled laboratory study. Seven fresh-frozen cadaver knees were used (age, 48 ± 12.5 years). First, intact knee kinematics was tested with a robotic-universal force sensor testing system under 2 loading conditions. An 89-N anterior load was applied, and an anterior tibial translation was measured at knee flexion angles of 0°, 30°, 60°, and 90°. Then, combined rotatory loads of 7-N·m valgus and 5-N·m internal tibial rotation were applied at 15° and 30° of knee flexion angles, which mimic the pivot shift. Afterward, only the AM bundle of the ACL was cut arthroscopically, keeping the posterolateral bundle intact. The knee was again tested using the intact knee kinematics to measure the in situ force of the AM bundle. Then, arthroscopic anatomic AM bundle reconstruction was performed with an allograft, and the knee was tested to give the in situ force of the reconstructed AM bundle. Knee kinematics under the 3 conditions (intact, anatomic AM augmentation, and nonanatomic high AM augmentation) and the in situ force were compared and analyzed. The high AM graft had significantly lower in situ force than the intact and anatomic reconstructed AM bundle at 0° of knee flexion (P < .05) and the intact AM bundle at 30° of knee flexion under anterior tibial loading. There were no differences between anatomic graft and intact AM bundle. The high AM graft also had a significantly lower in situ force than the intact and anatomic reconstructed AM with simulated pivot-shift loading at 15° and 30° of flexion (P < .05). Under anterior tibial and rotatory loading, there was a difference in tibial displacement between anatomic and high AM reconstructions and between the high AM graft and intact ACL under rotational loading with the knee at 15° of flexion. Anatomic AM augmentation can lead to biomechanical advantages at time zero when compared with the nonanatomic (high AM) augmentation. Anatomic AM augmentation better restores the knee kinematics to the intact ACL state.

Arthroscopic single-bundle anterior cruciate ligament reconstruction with six-strand hamstring tendon allograft versus bone-patellar tendon-bone allograft.

PubMed

Dai, Chengliang; Wang, Fei; Wang, Xiaomeng; Wang, Ruipeng; Wang, Shengjie; Tang, Shiyu

2016-09-01

The aim of this study was to compare the clinical outcomes of arthroscopic single-bundle anterior cruciate ligament (ACL) reconstruction with six-strand hamstring tendon (HT) allograft versus bone-patellar tendon-bone (BPTB) allograft. The prospective randomized controlled trial was included 129 patients. Sixty-nine patients received reconstruction with six-strand HT allografts (HT group), whereas 60 patients with BPTB allografts (BPTB group). Outcome assessment included re-rupture findings, International Knee Documentation Committee (IKDC) scores, Lysholm scores, KT-1000 arthrometer, Lachman test, pivot-shift test, range of motion (ROM) and single-leg hop test. At a mean follow-up of 52 months, 113 patients (HT group, 61 patients; BPTB group, 52 patients) completed a minimum 4-year follow-up. Four patients in HT group and six in BPTB group experienced ACL re-rupture (6.2 vs. 10.3 %) and received revision surgery. Significant between-group differences were observed in KT-1000 outcomes and pivot-shift test 1 (1.2 ± 1.5 vs. 1.8 ± 1.3, p = 0.025; positive rate 6.5 vs. 18.9 %, p = 0.036), 2 (1.1 ± 1.4 vs. 1.6 ± 1.2, p = 0.044; 8.1 vs. 20.7 %, p = 0.039), 4 (1.1 ± 1.5 vs. 1.7 ± 1.4, p = 0.031; 9.7 vs. 25 %, p = 0.012) years postoperatively. The outcomes between the two groups were comparable in terms of IKDC scores, Lysholm scores, Lachman test, ROM and single-leg hop test. Six-strand HT allograft achieved superior anteroposterior and rotational stability after single-bundle ACL reconstruction. It is a reasonable graft substitute for ACL reconstruction. II.

Anterior Cruciate Ligament Injury, Reconstruction, and the Optimization of Outcome

PubMed Central

Bliss, James Philip

2017-01-01

Anterior cruciate ligament reconstruction (ACLR) provides an established surgical intervention to control pathological tibiofemoral translational and rotational movement. ACLR is a safe and reproducible intervention, but there remains an underlying rate of failure to return to preinjury sporting activity levels. Postoperative pathological laxity and graft reinjury remain concerns. Previously, unrecognized meniscal lesions, disruption of the lateral capsule, and extracapsular structures offer potential avenues to treat and to therefore improve kinematic outcome and functional results, following reconstruction. Addressing laterally based injuries may also improve the durability of intraarticular ACLR. Improving the anterior cruciate ligament (ACL) graft replication of the normal ACL attachment points on the femur and the tibia, using either double bundle or anatomical single bundle techniques, improves kinematics, which may benefit outcome and functionality, following reconstruction. PMID:28966384

Double-Bundle Anterior Cruciate Ligament Reconstruction Using Hamstring Tendon Hybrid Grafts in Patients Over 40 Years of Age: Comparisons Between Different Age Groups.

PubMed

Nishio, Yusuke; Kondo, Eiji; Onodera, Jun; Onodera, Tomohiro; Yagi, Tomonori; Iwasaki, Norimasa; Yasuda, Kazunori

2018-05-01

Several recent studies have reported that favorable clinical results and a high level of patient satisfaction can generally be obtained with no increased risk of complications after single-bundle anterior cruciate ligament (ACL) reconstruction performed in patients >40 years of age. However, no studies have yet clarified the age-based differences in clinical outcomes after double-bundle reconstruction. To compare clinical outcomes after double-bundle ACL reconstruction using hamstring tendon hybrid grafts between patients in 2 different age groups: ≥40 years and <40 years. Cohort study; Level of evidence, 3. A retrospective study was conducted using 96 patients (48 men, 48 women ; mean age, 37 years) who underwent unilateral ACL reconstruction between 2008 and 2011. These patients were divided into 2 groups: group M included patients ≥40 years of age (n = 40 patients), and group Y included patients <40 years of age (n = 56 patients). All patients underwent the same anatomic double-bundle ACL reconstruction procedure. Clinical outcomes were evaluated at 2 years after surgery. Tunnel enlargement was also evaluated by computed digital radiography at 1 week and 2 years after surgery. Mean postoperative side-to-side differences in anterior laxity were 0.5 ± 1.9 mm and 1.2 ± 1.5 mm in groups M and Y, respectively; there was a significant difference between the 2 groups ( P = .039). There were no significant differences between the groups in Lysholm knee scores, International Knee Documentation Committee (IKDC) scores, or peak muscle torque of the hamstring. On the other hand, peak muscle torque of the quadriceps was significantly lower in group M (81%) than in group Y (89%) ( P = .025). With respect to femoral tunnel enlargement, the posterolateral tunnel in group M was significantly larger than that in group Y on anteroposterior and lateral radiographs ( P = .015 and P = .002, respectively). Equivalent clinical outcomes were seen between the 2 age groups after double-bundle ACL reconstruction. Postoperative anterior laxity was significantly less in older patients than in younger patients, however, older patients had significantly less quadriceps muscle strength than younger patients. Surgeons should be aware of residual muscle weakness and tunnel enlargement when performing double-bundle ACL reconstruction in older patients.

A systematic review of single- versus double-bundle ACL reconstruction using the anatomic anterior cruciate ligament reconstruction scoring checklist.

PubMed

Desai, Neel; Alentorn-Geli, Eduard; van Eck, Carola F; Musahl, Volker; Fu, Freddie H; Karlsson, Jón; Samuelsson, Kristian

2016-03-01

The aim of this systematic review was to apply the anatomic ACL reconstruction scoring checklist (AARSC) and to evaluate the degree to which clinical studies comparing single-bundle (SB) and double-bundle (DB) ACL reconstructions are anatomic. A systematic electronic search was performed using the databases PubMed (MEDLINE), EMBASE and Cochrane Library. Studies published from January 1995 to January 2014 comparing SB and DB ACL reconstructions with clinical outcome measurements were included. The items from the AARSC were recorded for both the SB and DB groups in each study. Eight-thousand nine-hundred and ninety-four studies were analysed, 77 were included. Randomized clinical trials (29; 38%) and prospective comparative studies (29; 38%) were the most frequent study type. Most studies were published in 2011 (19; 25%). The most commonly reported items for both SB and DB groups were as follows: graft type (152; 99%), femoral and tibial fixation method (149; 97% respectively), knee flexion angle during graft tensioning (124; 8%) and placement of the tibial tunnel at the ACL insertion site (101; 66%). The highest level of documentation used for ACL tunnel position for both groups was often one dimensional, e.g. drawing, operative notes or o'clock reference. The DB reconstruction was in general more thoroughly reported. The means for the AARSC were 6.9 ± 2.8 for the SB group and 8.3 ± 2.8 for the DB group. Both means were below a proposed required minimum score of 10 for anatomic ACL reconstruction. There was substantial underreporting of surgical data for both the SB and DB groups in clinical studies. This underreporting creates difficulties when analysing, comparing and pooling results of scientific studies on this subject.

Intercondylar roof impingement pressure after anterior cruciate ligament reconstruction in a porcine model.

PubMed

Iriuchishima, Takanori; Tajima, Goro; Ingham, Sheila J M; Shen, Wei; Horaguchi, Takashi; Saito, Akiyoshi; Smolinski, Patrick; Fu, Freddie H

2009-06-01

Anterior cruciate ligament (ACL) graft impingement against the intercondylar roof has been postulated, but not thoroughly investigated. The roof impingement pressure changes with different tibial and femoral tunnel positions in ACL reconstruction. Anterior tibial translation is also affected by the tunnel positions of ACL reconstruction. The study design included a controlled laboratory study. In 15 pig knees, the impingement pressure between ACL and intercondylar roof was measured using pressure sensitive film before and after ACL single bundle reconstruction. ACL reconstructions were performed in each knee with two different tibial and femoral tunnel position combinations: (1) tibial antero-medial (AM) tunnel to femoral AM tunnel (AM to AM) and (2) tibial postero-lateral (PL) tunnel to femoral High-AM tunnel (PL to High-AM). Anterior tibial translation (ATT) was evaluated after each ACL reconstruction using robotic/universal force-moment sensor testing system. Neither the AM to AM nor the PL to High-AM ACL reconstruction groups showed significant difference when compared with intact ACL in roof impingement pressure. The AM to AM group had a significantly higher failure load than PL to High-AM group. This study showed how different tunnel placements affect the ACL-roof impingement pressure and anterior-posterior laxity in ACL reconstruction. Anatomical ACL reconstruction does not cause roof impingement and it has a biomechanical advantage in ATT when compared with non-anatomical ACL reconstructions in the pig knee. There is no intercondylar roof impingement after anatomical single bundle ACL reconstruction.

Biomechanical Comparison: Single-Bundle versus Double-Bundle Posterior Cruciate Ligament Reconstruction Techniques.

PubMed

Milles, Jeffrey L; Nuelle, Clayton W; Pfeiffer, Ferris; Stannard, James P; Smith, Patrick; Kfuri, Mauricio; Cook, James L

2017-05-01

Controversy exists regarding double-bundle (DB) versus single-bundle (SB) posterior cruciate ligament (PCL) reconstruction, with differences in multiple variables affecting biomechanical and clinical results. Our objective was to compare immediate postimplantation biomechanics of SB versus DB reconstructions to determine the relative importance of restoring both PCL bundles versus total graft volume. Twenty knees were randomly assigned to five techniques ( n  = 4 knees/technique), performed by three surgeons experienced in their technique(s), three SB techniques ( n  = 12; all-inside arthroscopic inlay, all-inside suspensory fixation, and arthroscopic-assisted open onlay), and two DB techniques ( n  = 8; arthroscopic-assisted open inlay and all-inside suspensory fixation). Each knee was tested in three conditions: PCL-intact, PCL-deficient, and post-PCL reconstruction. Testing consisted of a posterior-directed force at four knee flexion angles, 10, 30, 60, and 90 degrees, to measure load to 5 mm of posterior displacement, maximum displacement (at 100 N load), and stiffness. Data for each knee were normalized, combined into two groups (SB and DB), and then compared using one-way analysis of variance. Graft volumes were calculated and analyzed to determine if differences significantly influenced the biomechanical results. Intact knees were stiffer than both groups at most angles ( p  < 0.02; p  < 0.05). DB was stiffer than SB at all angles except 30 degrees ( p  < 0.05). Intact knees had less laxity than SB ( p  < 0.03) and DB ( p  < 0.05) at 60 and 90 degrees. DB had less laxity than SB at all angles except 60 degrees ( p  < 0.05). Intact knees required more load than SB at 30, 60, and 90 degrees ( p  < 0.01) and more than DB at 60 and 90 degrees ( p  < 0.05). DB required more load than SB at 30, 60, and 90 degrees ( p  < 0.01). Graft volumes did not have strong correlations ( r  = 0.13-0.37) to any measurements. Neither group of PCL reconstruction techniques was able to replicate native PCL biomechanics. DB reconstructions were biomechanically superior to SB reconstructions; they may be preferred for clinical use when immediate post-reconstruction graft strength and stability are critical. These results were not strongly influenced by graft size differences, further supporting the PCL codominance theory. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

ACL reconstruction with hamstring tendon autograft and accelerated brace-free rehabilitation: a systematic review of clinical outcomes

PubMed Central

van Melick, Nicky; van Mourik, Jan B A; Reijman, Max; van Rhijn, Lodewijk W

2018-01-01

Objective To investigate the clinical outcomes after hamstring tendon autograft ACL reconstruction (ACLR) with accelerated, brace-free rehabilitation. Design Systematic review according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Data sources Embase, MEDLINE Ovid, Web of Science, Cochrane CENTRAL and Google scholar from 1 January 1974 to 31 January 2017. Eligibility criteria for selecting studies Study designs reporting outcomes in adults after arthroscopic, primary ACLR with hamstring autograft and accelerated, brace-free rehabilitation. Results Twenty-four studies were included in the review. The clinical outcomes after hamstring tendon autograft ACLR with accelerated brace-free rehabilitation were the following: (1) early start of open kinetic exercises at 4 weeks in a limited range of motion (ROM, 90°−45°) and progressive concentric and eccentric exercises from 12 weeks did not alter outcomes, (2) gender and age did not influence clinical outcomes, (3) anatomical reconstructions showed better results than non-anatomical reconstructions, (4) there was no difference between single-bundle and double-bundle reconstructions, (5) femoral and tibial tunnel widening occurred, (6) hamstring tendons regenerated after harvest and (7) biological knowledge did not support return to sports at 4–6 months. Conclusions After hamstring tendon autograft ACLR with accelerated brace-free rehabilitation, clinical outcome is similar after single-bundle and double-bundle ACLR. Early start of open kinetic exercises at 4 weeks in a limited ROM (90°−45°) and progressive concentric and eccentric exercises from 12 weeks postsurgery do not alter clinical outcome. Further research should focus on achievement of best balance between graft loading and graft healing in the various rehabilitation phases after ACLR as well as on validated, criterion-based assessments for safe return to sports. Level of evidence Level 2b; therapeutic outcome studies. PMID:29682311

ACL double-bundle reconstruction with one tibial tunnel provides equal stability compared to two tibial tunnels.

PubMed

Drews, Björn Holger; Seitz, Andreas Martin; Huth, Jochen; Bauer, Gerhard; Ignatius, Anita; Dürselen, Lutz

2017-05-01

The purpose of this study was to investigate whether an anterior cruciate ligament (ACL) double-bundle reconstruction with one tibial tunnel displays the same in vitro stability as a conventional double-bundle reconstruction with two tibial tunnels when using the same tensioning protocol. In 11 fresh-frozen cadaveric knees, ACL double-bundle reconstruction with one and two tibial tunnels was performed. The two grafts were tightened using 80 N in different flexion angles (anteromedial-bundle at 60° and posterolateral-bundle at 15°). Anterior tibial translation (134 N) and translation with combined rotatory and valgus loads (10 Nm valgus stress and 4 Nm internal tibial torque) were determined at 0°, 30°, 60° and 90° flexion. Measurements were taken in intact ACL, resected ACL, three-tunnel reconstruction and four-tunnel reconstruction. Additionally, the tension on the grafts was determined. Student's t test was performed for statistical analysis of the related samples. Significance was set at p < 0.017 according to Bonferroni correction. The two reconstructive techniques displayed no significant differences in comparison with the intact ACL in anterior tibial translation at 0°, 60° and 90° of flexion. The same results were obtained for the anterior tibial translation with a combined rotatory load at 60° and 90°. When directly comparing both reconstructive techniques, there were no significant differences for the anterior tibial translation and combined rotatory load at all flexion angles. The measured tension on grafts displayed similar load sharing between both bundles. Except at full extension, both grafts displayed a significantly different tension increase under anterior tibial translation for both techniques (p = 0.0086). Tightening both bundles in ACL double-bundle reconstruction with one or two tibial tunnels in different flexion angles achieved comparable restoration of stability, although there was different load sharing on the bundles. With regard to individualized ACL reconstruction, the double-bundle technique with one tibial tunnel offers a possibility to address small tibial insertion sites without compromising the advantages of a double-bundle procedure.

Fiber-bundle-basis sparse reconstruction for high resolution wide-field microendoscopy.

PubMed

Mekhail, Simon Peter; Abudukeyoumu, Nilupaer; Ward, Jonathan; Arbuthnott, Gordon; Chormaic, Síle Nic

2018-04-01

In order to observe deep regions of the brain, we propose the use of a fiber bundle for microendoscopy. Fiber bundles allow for the excitation and collection of fluorescence as well as wide field imaging while remaining largely impervious to image distortions brought on by bending. Furthermore, their thin diameter, from 200-500 µ m, means their impact on living tissue, though not absent, is minimal. Although wide field imaging with a bundle allows for a high temporal resolution since no scanning is involved, the largest criticism of bundle imaging is the drastically lowered spatial resolution. In this paper, we make use of sparsity in the object being imaged to up sample the low resolution images from the fiber bundle with compressive sensing. We take each image in a single shot by using a measurement basis dictated by the quasi-crystalline arrangement of the bundle's cores. We find that this technique allows us to increase the resolution of a typical image taken through a fiber bundle.

Transtibial vs anatomical single bundle technique for anterior cruciate ligament reconstruction: A Retrospective Cohort Study.

PubMed

Kilinc, Bekir Eray; Kara, Adnan; Oc, Yunus; Celik, Haluk; Camur, Savas; Bilgin, Emre; Erten, Yunus Turgay; Sahinkaya, Turker; Eren, Osman Tugrul

2016-05-01

Most of the ACL reconstruction is done with isometric single-bundle technique. Traditionally, surgeons were trained to use the transtibial technique (TT) for drilling the femoral tunnel. Our study compared the early postoperative period functional and clinical outcomes of patients who had ACL reconstruction with TT and patients who had ACL reconstruction with anatomical single-bundle technique (AT). Fifty-five patients who had ACL reconstruction and adequate follow-up between January 2010-December 2013 were included the study. Patients were grouped by their surgery technique. 28 patients included into anatomical single-bundle ACL reconstruction surgery group (group 1) and 27 patients were included into transtibial AC reconstruction group (group 2). Average age of patients in group 1 and group 2 was 28.3 ± 6, and 27.9 ± 6.4, respectively. Lachman and Pivot-shift tests were performed to patients. Laxity was measured by KT-1000 arthrometer test with 15, 20 and 30 pound power. All patients' muscle strength between both extremities were evaluated with Cybex II (Humac) at 60°/sec, 240°/sec frequencies with flexion and extension peak torque. The maximum force values of non-operated knee and the operated knee were compared to each other. Groups were evaluated by using International Knee Documentation Committee (IKDC) knee ligament healing Standard form, IKDC activity scale, modified Lysholm and Cincinnati evaluation forms. Return to work and exercise time of patients were compared. Functional and clinical outcomes of two groups were compared. NCSS 2007 and PASS 2008 Statistical Software programs were used for statistical analysis. There was no statistically significant difference between Lachman and Pivot-shift results (p > 0.01). Positive value of Pivot-shift test and incidence of anterior translation in Lachman test were higher in the patients who had TT. Lysholm activity level of patients who had TT, 33.3% (n = 9) were excellent, 51.9% (n = 14) were good and 14.8% (n = 4) were moderate; patients who had AT, 57.1% (n = 16) were excellent, 39.3% (n = 11) were good and 3.6% (n = 1) was good level. There was no statistically significant difference between Lysholm Activity level of the patients (p < 0.01). Lysholm Activity level of patients who had AT significantly higher than TT. There was no statistically significant difference between Modified Cincinnati activity level of the patients (p < 0.05). Modified Cincinnati activity level of patients who had AT were significantly higher than those had TT. There was no statistically significant difference between two groups with post treatment IKDC activity level (p < 0.01). Intense activity after treatment rate of patient who had AT was significantly higher than those had TT. There was statistically significant difference between Cybex extension-flexion 60 measurement and extension 240 measurement of the patients (p < 0.01). KT-1000 arthrometer test results with AT was better than the TT in antero-posterior translation of the knee kinematics at 20 and 30 pound of forces. Return to exercise time of patients who had TT was significantly higher than those had AT (p < 0.01). There was no statistically significant difference between return to work time of patients (p > 0.05). Single-bundle anatomic ACL reconstruction was better than the TT in term of clinical, functional, and laboratory results. We believe that AT ACL reconstruction will increase in use and traditional method which is TT ACL reconstruction surgery will decrease in the long term. Theoretically, anatomic relocation of the ACL can provide better knee kinematics. Copyright © 2016 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.

Surgical Techniques for the Reconstruction of Medial Collateral Ligament and Posteromedial Corner Injuries of the Knee: A Systematic Review.

PubMed

DeLong, Jeffrey M; Waterman, Brian R

2015-11-01

To systematically review reconstruction techniques of the medial collateral ligament (MCL) and associated medial structures of the knee (e.g., posterior oblique ligament). A systematic review of Medline/PubMed Database (1966 to November 2013), reference list scanning and citation searches of included articles, and manual searches of high-impact journals (2000 to July 2013) and conference proceedings (2009 to July 2013) were performed to identify publications describing MCL reconstruction techniques of the knee. Exclusion criteria included (1) MCL primary repair techniques or advancement procedures, (2) lack of clear description of MCL reconstruction technique, (3) animal models, (4) nonrelevant study design, (5) and foreign language articles without available translation. After review of 4,600 references, 25 publications with 359 of 388 patients (92.5%) were isolated for analysis, including 18 single-bundle MCL and 10 double-bundle reconstruction techniques. Only 2 techniques were classified as anatomic reconstructions, and clinical and objective outcomes (n = 28; 100% <3 mm side-to-side difference [SSD]) were superior to those with nonanatomic reconstruction (n = 182; 79.1% <3 mm SSD) and tendon transfer techniques (n = 114; 52.6% <3 mm SSD). This systematic review demonstrated that numerous medial reconstruction techniques have been used in the treatment of isolated and combined medial knee injuries in the existent literature. Many variations exist among reconstruction techniques and may differ by graft choices, method of fixation, number of bundles, tensioning protocol, and degree of anatomic restoration of medial and posteromedial corner knee restraints. Further studies are required to better ascertain the comparative clinical outcomes with anatomic, non-anatomic, and tendon transfer techniques for medial knee reconstruction. Level IV, systematic review of level IV studies and surgical techniques. Published by Elsevier Inc.

Current Trends in Anterior Cruciate Ligament Reconstruction: A Review

PubMed Central

Vaishya, Raju; Ingole, Sachin; Vijay, Vipul

2015-01-01

Anterior cruciate ligament reconstruction (ACLR) is an accepted and established surgical technique for anterior cruciate ligament (ACL) injuries and is now being practiced across the globe in increasing numbers. Although most patients get good to excellent results in the short-term after ACLR, its consequences in the long-term in prevention or acceleration of knee osteoarthritis (OA) are not yet well-defined. Still, there are many debatable issues related to ACLR, such as the appropriate timing of surgery, graft selection, fixation methods of the graft, operative techniques, rehabilitation after surgery, and healing augmentation techniques. Most surgeons prefer not to wait long after an ACL injury to do an ACLR, as delayed reconstruction is associated with secondary damages to the intra- and periarticular structures of the knee. Autografts are the preferred choice of graft in primary ACLR, and hamstring tendons are the most popular amongst surgeons. Single bundle ACLR is being practiced by the majority, but double bundle ACLR is getting popular due to its theoretical advantage of providing more anatomical reconstruction. A preferred construct is the interference fixation (Bio-screw) at the tibial site and the suspensory method of fixation at the femoral site. In a single bundle hamstring graft, a transportal approach for creating a femoral tunnel has recently become more popular than the trans-tibial technique. Various healing augmentation techniques, including the platelet rich plasma (PRP), have been tried after ACLR, but there is still no conclusive proof of their efficacy. Accelerated rehabilitation is seemingly more accepted immediately after ACLR. PMID:26697280

Effects of Single-Bundle and Double-Bundle ACL Reconstruction on Tibiofemoral Compressive Stresses and Joint Kinematics During Simulated Squatting

PubMed Central

Mulcahey, Mary K.; Monchik, Keith O.; Yongpravat, Charlie; Badger, Gary J.; Fadale, Paul D.; Hulstyn, Michael J.; Fleming, Braden C.

2011-01-01

The purpose of this study was to compare tibiofemoral (TF) kinematics and TF compressive stresses between single bundle- (SB-) and double bundle-ACL reconstruction (DB-ACLR) during simulated squatting. Twelve matched pairs of fresh frozen cadaver knees were utilized. A simulated squat through 100° of knee flexion was performed in the ACL-intact joint. The ACL was transected and SB- and DB-ACLR procedures were performed in one knee of each pair. The squat was repeated. Knee kinematics were measured using a motion tracking system and the TF compressive forces were measured using thin film pressure sensors. The posterior shifts of the tibia for SB- and DB-ACLR knees were significantly greater than the ACL-intact condition for knee flexion angles 0° to 40° (p<.05). However, there was no difference between the SB- and DB-ACLR knees at any flexion angle (0° to 100°; p=.37). SB- and DB-ACLR knees had greater IE rotation than intact knees from 90° through 50° of flexion (p<.05), but not between 40° and full extension. There was no difference between SB- and DB-ACLR knees (p=.68). The TF compressive stresses of the DB-ACLR were significantly lower than intact for all angles except 10° (p=.06), whereas SB-ACLR knees did not differ from intact at flexion angles between 30° and 50° (p>.32). There were no significant differences between the two reconstruction conditions (p=.74). This study showed that there was no difference in the TF kinematics or compressive stresses between SB- and DB-ACLR, and only minor differences when compared to the intact state. PMID:21696962

Clinical and arthroscopic outcome of single bundle anterior cruciate ligament reconstruction: Comparison of remnant preservation versus conventional technique.

PubMed

Choi, Sungwook; Kim, Myung-Ku; Kwon, Yong Suk; Kang, Hyunseong

2017-10-01

The purpose of this study was to compare the clinical outcomes and second-look arthroscopic findings of remnant preservation technique with those of conventional anterior cruciate ligament (ACL) reconstruction in single bundle ACL reconstructions. One hundred sixty two consecutive patients underwent ACL reconstruction by one surgeon, with 93 patients receiving remnant preservation technique (Group A) and 69 patients receiving conventional ACL reconstruction (Group B). The mean follow-up was 15months. Clinical outcomes were assessed using Lysholm scores and the International Knee Documentation Committee form (IKDC form) evaluation. Post-operative knee stability was evaluated through manual knee laxity evaluation, pivot-shift test, and a Telos device. Differences in post-operative stability (manual knee laxity, pivot shift test and Telos device) were not significant between the groups (p=0.681, p=0.610, p=0.696). And also no significant differences were noted with respect to the IKDC form and the latest Lysholm scores. But in the second-look arthroscopic findings, synovial coverage was confirmed to be excellent in 36% (22/61) of Group A patients and 23% (7/30) of Group B patients. ACL reconstruction with both techniques was found to result in acceptable stability, clinical outcomes and second-look arthroscopic findings. With regard to synovial coverage, the remnant reservation techniques were found to be superior to conventional ACL reconstruction. Level III, retrospective comparative study. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of femur tunnel aperture location in patients undergoing transtibial and anatomical single-bundle anterior cruciate ligament reconstruction.

PubMed

Lee, Dae-Hee; Kim, Hyun-Jung; Ahn, Hyeong-Sik; Bin, Seong-Il

2016-12-01

Although three-dimensional computed tomography (3D-CT) has been used to compare femoral tunnel position following transtibial and anatomical anterior cruciate ligament (ACL) reconstruction, no consensus has been reached on which technique results in a more anatomical position because methods of quantifying femoral tunnel position on 3D-CT have not been consistent. This meta-analysis was therefore performed to compare femoral tunnel location following transtibial and anatomical ACL reconstruction, in both the low-to-high and deep-to-shallow directions. This meta-analysis included all studies that used 3D-CT to compare femoral tunnel location, using quadrant or anatomical coordinate axis methods, following transtibial and anatomical (AM portal or OI) single-bundle ACL reconstruction. Six studies were included in the meta-analysis. Femoral tunnel location was 18 % higher in the low-to-high direction, but was not significant in the deep-to-shallow direction, using the transtibial technique than the anatomical methods, when measured using the anatomical coordinate axis method. When measured using the quadrant method, however, femoral tunnel positions were significantly higher (21 %) and shallower (6 %) with transtibial than anatomical methods of ACL reconstruction. The anatomical ACL reconstruction techniques led to a lower femoral tunnel aperture location than the transtibial technique, suggesting the superiority of anatomical techniques for creating new femoral tunnels during revision ACL reconstruction in femoral tunnel aperture location in the low-to-high direction. However, the mean difference in the deep-to-shallow direction differed by method of measurement. Meta-analysis, Level II.

Trends in Anterior Cruciate Ligament Reconstruction in the Last Decade: A Web-Based Analysis.

PubMed

Yucens, Mehmet; Aydemir, Ahmet Nadir

2018-05-31

Anterior cruciate ligament (ACL) injury is known to be one of the most common knee joint injuries. ACL reconstruction can be similar to the native ACL in respect of graft morphology, tension, position, and orientation. ACL reconstruction can be applied with different surgery techniques, graft and fixation devices, and rehabilitation as ACL reconstruction is just as important as surgery. Although commonly known as a sports injury, ACL injuries are increasingly seen in the general population. The aim of this study was to investigate the trends in ACL injury treatment in the last decade especially the graft choice. The abstracts of a total of 2,622 papers which stated ACL in the title were investigated through a search on the Web of Knowledge. Main topics were created as the ACL reconstruction theme. ACL reconstruction was examined in the abstracts with graft choice as the main theme followed by single bundle, double bundle, sports, rehabilitation, revision, complication, skeletally immature, biomechanics and kinematics, fixation devices, meniscus, anesthesia and pain, tunnel, cell, and intra-articular injection. Of the total 2,622 documents, 2,129 were original articles and 181 were reviews. Most of the documents, 436 in number (16.6%), were published in the American Journal of Sports Medicine , followed by the Journal of Knee Surgery , Sports Traumatology , Arthroscopy at 264. Of the total documents published, 36.3% were from the United States followed by 8.5% from Japan. The author with the most publications was F.H. Fu with 94 publications followed by B.R. Bach with 41 publications. The hamstring graft was most used at 187 single use and comprising 52% of the total graft combinations. Most papers were published in 2016. In 2012, single and double bundle grafts were determined to a total of 23. The most common title investigated in papers was biomechanics and kinematics with a total of 241 publications followed by rehabilitation at 208. Throughout the years of the study period, the most common graft choice was hamstring autograft. Biomechanics and kinematics was the most common title investigated as biomechanics and rehabilitation are known to be just as important as surgery for a successful outcome and patient satisfaction. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Influence of knee flexion angle and transverse drill angle on creation of femoral tunnels in double-bundle anterior cruciate ligament reconstruction using the transportal technique: Three-dimensional computed tomography simulation analysis.

PubMed

Choi, Chong Hyuk; Kim, Sung-Jae; Chun, Yong-Min; Kim, Sung-Hwan; Lee, Su-Keon; Eom, Nam-Kyu; Jung, Min

2018-01-01

The purpose of this study was to find appropriate flexion angle and transverse drill angle for optimal femoral tunnels of anteromedial (AM) bundle and posterolateral (PL) bundle in double-bundle ACL reconstruction using transportal technique. Thirty three-dimensional knee models were reconstructed. Knee flexion angles were altered from 100° to 130° at intervals of 10°. Maximum transverse drill angle (MTA), MTA minus 10° and 20° were set up. Twelve different tunnels were determined by four flexion angles and three transverse drill angles for each bundle. Tunnel length, wall breakage, inter-tunnel communication and graft-bending angle were assessed. Mean tunnel length of AM bundle was >30mm at 120° and 130° of flexion in all transverse drill angles. Mean tunnel length of PL bundle was >30mm during every condition. There were ≥1 cases of wall breakage except at 120° and 130° of flexion with MTA for AM bundle. There was no case of wall breakage for PL bundle. Considering inter-tunnel gap of >2mm without communication and obtuse graft-bending angle, 120° of flexion and MTA could be recommended as optimal condition for femoral tunnels of AM and PL bundles. Flexion angle and transverse drill angle had combined effect on femoral tunnel in double-bundle ACL reconstruction using transportal technique. Achieving flexion angle of 120° and transverse drill angle close to the medial femoral condyle could be recommended as optimal condition for femoral tunnels of AM and PL bundles to avoid insufficient tunnel length, wall breakage, inter-tunnel communication and acute graft-bending angle. Copyright © 2017 Elsevier B.V. All rights reserved.

Tibial plateau fracture after primary anatomic double-bundle anterior cruciate ligament reconstruction: a case report.

PubMed

Gobbi, Alberto; Mahajan, Vivek; Karnatzikos, Georgios

2011-05-01

Tibial plateau fracture after primary anatomic double-bundle anterior cruciate ligament (ACL) reconstruction is rare. To our knowledge, this is the first case report of a tibial plateau fracture after primary anatomic double-bundle ACL reconstruction. In our patient the tibial plateau fracture occurred after a torsional injury to the involved extremity. The fracture occurred 4.5 years after the ACL reconstruction. The fracture was intra-articular Schatzker type IV and had a significant displacement. The patient was treated operatively by open reduction-internal fixation. He recovered well. Copyright © 2011 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

The role of isolated posterior cruciate ligament reconstruction in knees with combined posterior cruciate ligament and posterolateral complex injury.

PubMed

Lee, Dong-Yeong; Park, Young-Jin; Kim, Dong-Hee; Kim, Hyun-Jung; Nam, Dae-Cheol; Park, Jin-Sung; Hwang, Sun-Chul

2017-08-14

This is a meta-analysis comparing biomechanical outcomes to determine whether an isolated posterior cruciate ligament (PCL) reconstruction can restore normal knee kinematics in a combined PCL/posterolateral complex (PLC) injury and whether double-bundle (DB) PCL reconstruction is superior in controlling posterior and rotational laxity compared with single-bundle (SB) PCL reconstruction in a PCL/PLC-deficient knee. A number of electronic databases were searched for relevant articles published through August 2016 that compared biomechanical outcomes of PCL reconstruction in patients who underwent reconstruction for combined PCL/PLC deficiencies. Data were searched, extracted, analysed, and assessed for quality according to Cochrane Collaboration guidelines, and biomechanical outcomes were evaluated using various outcome values. The results are presented as relative ratios for binary outcomes and standard mean differences for continuous outcomes with 95% confidence intervals. Five biomechanical studies were included in this meta-analysis. There were significant differences in laxities such as posterior tibial translation (PTT), external rotation, varus rotation, and PTT coupled with external rotation in the isolated PCL reconstruction group compared with the native PCL group. Furthermore, there were no significant differences in laxities such as PTT, external rotation, or varus rotation between the SB and DB PCL reconstruction groups. Isolated PCL reconstruction, whether SB or DB, could not restore normal knee kinematics in the PCL/PLC-deficient knee. In such cases, residual laxity after isolated PCL reconstruction can be controlled successfully with PLC reconstruction. Therefore, simultaneous PCL and PLC reconstruction is recommended for patients with combined PCL/PLC injury.

Double incision iso-anatomical ACL reconstruction: the freedom to place the femoral tunnel within the anatomical attachment site without exception.

PubMed

Arnold, Markus P; Duthon, Victoria; Neyret, Philippe; Hirschmann, Michael T

2013-02-01

The present paper describes the rationale behind the surgical technique and the clinical results of the iso-anatomical, single bundle bone patellar-tendon bone anterior cruciate ligament (ACL) reconstruction. Using a second incision on the distal lateral femur an outside-in femoral tunnel is drilled. Guided by a special aiming device it is possible to place the femoral tunnel in the centre of the ACL footprint in every single case. Since every crucial step of the procedure is under visual control, the technique is safe and reliable, which is mirrored by good clinical results.

D Reconstruction with a Collaborative Approach Based on Smartphones and a Cloud-Based Server

NASA Astrophysics Data System (ADS)

Nocerino, E.; Poiesi, F.; Locher, A.; Tefera, Y. T.; Remondino, F.; Chippendale, P.; Van Gool, L.

2017-11-01

The paper presents a collaborative image-based 3D reconstruction pipeline to perform image acquisition with a smartphone and geometric 3D reconstruction on a server during concurrent or disjoint acquisition sessions. Images are selected from the video feed of the smartphone's camera based on their quality and novelty. The smartphone's app provides on-the-fly reconstruction feedback to users co-involved in the acquisitions. The server is composed of an incremental SfM algorithm that processes the received images by seamlessly merging them into a single sparse point cloud using bundle adjustment. Dense image matching algorithm can be lunched to derive denser point clouds. The reconstruction details, experiments and performance evaluation are presented and discussed.

A compressed sensing approach for resolution improvement in fiber-bundle based endomicroscopy

NASA Astrophysics Data System (ADS)

Dumas, John P.; Lodhi, Muhammad A.; Bajwa, Waheed U.; Pierce, Mark C.

2018-02-01

Endomicroscopy techniques such as confocal, multi-photon, and wide-field imaging have all been demonstrated using coherent fiber-optic imaging bundles. While the narrow diameter and flexibility of fiber bundles is clinically advantageous, the number of resolvable points in an image is conventionally limited to the number of individual fibers within the bundle. We are introducing concepts from the compressed sensing (CS) field to fiber bundle based endomicroscopy, to allow images to be recovered with more resolvable points than fibers in the bundle. The distal face of the fiber bundle is treated as a low-resolution sensor with circular pixels (fibers) arranged in a hexagonal lattice. A spatial light modulator is located conjugate to the object and distal face, applying multiple high resolution masks to the intermediate image prior to propagation through the bundle. We acquire images of the proximal end of the bundle for each (known) mask pattern and then apply CS inversion algorithms to recover a single high-resolution image. We first developed a theoretical forward model describing image formation through the mask and fiber bundle. We then imaged objects through a rigid fiber bundle and demonstrate that our CS endomicroscopy architecture can recover intra-fiber details while filling inter-fiber regions with interpolation. Finally, we examine the relationship between reconstruction quality and the ratio of the number of mask elements to the number of fiber cores, finding that images could be generated with approximately 28,900 resolvable points for a 1,000 fiber region in our platform.

Computational imaging through a fiber-optic bundle

NASA Astrophysics Data System (ADS)

Lodhi, Muhammad A.; Dumas, John Paul; Pierce, Mark C.; Bajwa, Waheed U.

2017-05-01

Compressive sensing (CS) has proven to be a viable method for reconstructing high-resolution signals using low-resolution measurements. Integrating CS principles into an optical system allows for higher-resolution imaging using lower-resolution sensor arrays. In contrast to prior works on CS-based imaging, our focus in this paper is on imaging through fiber-optic bundles, in which manufacturing constraints limit individual fiber spacing to around 2 μm. This limitation essentially renders fiber-optic bundles as low-resolution sensors with relatively few resolvable points per unit area. These fiber bundles are often used in minimally invasive medical instruments for viewing tissue at macro and microscopic levels. While the compact nature and flexibility of fiber bundles allow for excellent tissue access in-vivo, imaging through fiber bundles does not provide the fine details of tissue features that is demanded in some medical situations. Our hypothesis is that adapting existing CS principles to fiber bundle-based optical systems will overcome the resolution limitation inherent in fiber-bundle imaging. In a previous paper we examined the practical challenges involved in implementing a highly parallel version of the single-pixel camera while focusing on synthetic objects. This paper extends the same architecture for fiber-bundle imaging under incoherent illumination and addresses some practical issues associated with imaging physical objects. Additionally, we model the optical non-idealities in the system to get lower modelling errors.

Pseudoaneurysm of the articular branch of the descending genicular artery following double-bundle anterior cruciate ligament reconstruction.

PubMed

Tsubosaka, Masanori; Matsushita, Takehiko; Kuroda, Ryosuke; Matsumoto, Tomoyuki; Kurosaka, Masahiro

2017-09-01

This report describes a case of a pseudoaneurysm of the articular branch of the descending genicular artery following double-bundle anterior cruciate ligament (ACL) reconstruction. An 18-year-old male received double-bundle ACL reconstruction. During ACL reconstruction, a far anteromedial portal was created for femoral tunnel drilling. The patient presented with pulsatile swelling on the medial side of the knee on the second post-operative day. The pseudoaneurysm was diagnosed using contrast computed tomography and Doppler ultrasonography and was subsequently treated by embolization with a microcatheter. Although a vascular injury is a very rare complication of knee arthroscopy, it should be considered a possibility in patients who undergo such procedures. V.

Development and Characterization of a Dither-Based Super-Resolution Reconstruction Method for Fiber Imaging Arrays

NASA Astrophysics Data System (ADS)

Languirand, Eric Robert

Chemical imaging is an important tool for providing insight into function, role, and spatial distribution of analytes. This thesis describes the use of imaging fiber bundles (IFB) for super-resolution reconstruction using surface enhanced Raman scattering (SERS) showing improvement in resolution with arrayed bundles for the first time. Additionally this thesis describes characteristics of the IFB with regards to cross-talk as a function of aperture size. The first part of this thesis characterizes the IFB for both tapered and untapered bundles in terms of cross-talk. Cross-talk is defined as the amount of light leaking from a central fiber element in the imaging fiber bundle to surrounding fiber elements. To make this measurement ubiquitous for all imaging bundles, quantum dots were employed. Untapered and tapered IFB possess cross-talk of 2% or less, with fiber elements down to 32nm. The second part of this thesis employs a super resolution reconstruction algorithm using projection onto convex sets for resolution improvement. When using IFB arrays, the point spread function (PSF) of the array can be known accurately if the fiber elements over fill the pixel detector array. Therefore, the use of the known PSF compared to a general blurring kernel was evaluated. Relative increases in resolution of 12% and 2% at the 95% confidence level are found, when compared to a reference image, for the general blurring kernel and PSF, respectively. The third part of this thesis shows for the first time the use of SERS with a dithered IFB array coupled with super-resolution reconstruction. The resolution improvement across a step-edge is shown to be approximately 20% when compared to a reference image. This provides an additional means of increasing the resolution of fiber bundles beyond that of just tapering. Furthermore, this provides a new avenue for nanoscale imaging using these bundles. Lastly, synthetic data with varying degrees of signal-to-noise (S/N) were employed to explore the relationship S/N has with the reconstruction process. It is generally shown that increasing the number images used in the reconstruction process and increasing the S/N will improve the reconstruction providing larger increases in resolution.

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION USING THE DOUBLE-BUNDLE TECHNIQUE - EVALUATION IN THE BIOMECHANICS LABORATORY.

PubMed

D'Elia, Caio Oliveira; Bitar, Alexandre Carneiro; Castropil, Wagner; Garofo, Antônio Guilherme Padovani; Cantuária, Anita Lopes; Orselli, Maria Isabel Veras; Luques, Isabela Ugo; Duarte, Marcos

2011-01-01

The objective of this study was to describe the methodology of knee rotation analysis using biomechanics laboratory instruments and to present the preliminary results from a comparative study on patients who underwent anterior cruciate ligament (ACL) reconstruction using the double-bundle technique. The protocol currently used in our laboratory was described. Three-dimensional kinematic analysis was performed and knee rotation amplitude was measured on eight normal patients (control group) and 12 patients who were operated using the double-bundle technique, by means of three tasks in the biomechanics laboratory. No significant differences between operated and non-operated sides were shown in relation to the mean amplitudes of gait, gait with change in direction or gait with change in direction when going down stairs (p > 0.13). The preliminary results did not show any difference in the double-bundle ACL reconstruction technique in relation to the contralateral side and the control group.

Short term results of anterior cruciate ligament augmentation in professional and amateur athletes.

PubMed

Yazdi, Hamidreza; Torkaman, Ali; Ghahramani, Morteza; Moradi, Amin; Nazarian, Ara; Ghorbanhoseini, Mohammad

2017-06-01

Anterior cruciate ligament (ACL) reconstruction is a widely accepted procedure; however, controversies exist about ACL augmentation. The purpose of this study was to assess the clinical outcomes of ACL augmentation in professional and amateur athletes with isolated single bundle ACL tears. A consecutive series of professional and amateur athletes with partial ACL tears who underwent selective bundle reconstruction were analyzed. Stability was assessed with the Lachman test, anterior-drawer test, pivot-shift test and KT-1000 arthrometer. Functional assessment was performed using the subjective Lysholm questionnaire. Fifty-six patients were enrolled. The mean follow-up period was 19.3 months. All patients had posterolateral bundle (PLB) tears, and no anteromedial bundle (AMB) tears were found. The Lysholm score improved significantly from 78 (SD = 2.69) preoperatively to 96 (SD = 3.41) postoperatively (P value <0.0001). The pivot-shift test, Lachman test and anterior-drawer test results were negative in all cases postoperatively. Anterior tibial translation from neutral was 4.9 mm (SD = 2.7) preoperatively, and decreased significantly to 2.1 (SD = 0.6) postoperatively, measured with a KT-1000 arthrometer (P value <0.00001). In this study, we showed that ACL augmentation had good results in symptomatic professional and amateur athletes, and although further studies are needed to investigate long-term results, we recommend this surgery for all symptomatic athletic patients, especially those who would like to maintain an active lifestyle. Level of evidence IV.

Systemic Review of Anatomic Single- Versus Double-Bundle Anterior Cruciate Ligament Reconstruction: Does Femoral Tunnel Drilling Technique Matter?

PubMed

Zhang, Yang; Xu, Caiqi; Dong, Shiqui; Shen, Peng; Su, Wei; Zhao, Jinzhong

2016-09-01

To provide an up-to-date assessment of the difference between anatomic double-bundle anterior cruciate ligament (ACL) reconstruction (DB-ACLR) and anatomic single-bundle ACL reconstruction (SB-ACLR). We hypothesized that anatomic SB-ACLR using independent femoral drilling technique would be able to achieve kinematic stability as with anatomic DB-ACLR. A comprehensive Internet search was performed to identify all therapeutic trials of anatomic DB-ACLR versus anatomic SB-ACLR. Only clinical studies of Level I and II evidence were included. The comparative outcomes were instrument-measured anterior laxity, Lachman test, pivot shift, clinical outcomes including objective/subjective International Knee Documentation Committee (IKDC) score, Lysholm score, Tegner activity scale and complication rates of extension/flexion deficits, graft failure, and early osteoarthritis. Subgroup analyses were performed for femoral tunnel drilling techniques including independent drilling and transtibial (TT) drilling. Twenty-two clinical trials of 2,261 anatomically ACL-reconstructed patients were included in the meta-analysis. Via TT drilling technique, anatomic DB-ACLR led to improved instrument-measured anterior laxity with a standard mean difference (SMD) of -0.42 (95% confidence interval [CI] = -0.81 to -0.02), less rotational instability measured by pivot shift (SMD = 2.76, 95% CI = 1.24 to 6.16), and higher objective IKDC score with odds ratio (OR) of 2.28 (95% CI = 1.19 to 4.36). Via independent drilling technique, anatomic DB-ACLR yielded better pivot shift (SMD = 2.04, 95% CI = 1.36 to 3.05). Anatomic DB-ACLR also revealed statistical significance in subjective IKDC score compared with anatomic SB-ACLR (SMD = 0.27, 95% CI = 0.05 to 0.49). Anatomic DB-ACLR showed better anterior and rotational stability and higher objective IKDC score than anatomic SB-ACLR via TT drilling technique. Via independent drilling technique, however, anatomic DB-ACLR only showed superiority of rotational stability. All clinical function outcomes except subjective IKDC score were not significantly different between anatomic DB-ACLR and SB-ACLR. Level II, meta-analysis of Level I and II studies. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Parallel Information Processing (Image Transmission Via Fiber Bundle and Multimode Fiber

NASA Technical Reports Server (NTRS)

Kukhtarev, Nicholai

2003-01-01

Growing demand for visual, user-friendly representation of information inspires search for the new methods of image transmission. Currently used in-series (sequential) methods of information processing are inherently slow and are designed mainly for transmission of one or two dimensional arrays of data. Conventional transmission of data by fibers requires many fibers with array of laser diodes and photodetectors. In practice, fiber bundles are also used for transmission of images. Image is formed on the fiber-optic bundle entrance surface and each fiber transmits the incident image to the exit surface. Since the fibers do not preserve phase, only 2D intensity distribution can be transmitted in this way. Each single mode fiber transmit only one pixel of an image. Multimode fibers may be also used, so that each mode represent different pixel element. Direct transmission of image through multimode fiber is hindered by the mode scrambling and phase randomization. To overcome these obstacles wavelength and time-division multiplexing have been used, with each pixel transmitted on a separate wavelength or time interval. Phase-conjugate techniques also was tested in, but only in the unpractical scheme when reconstructed image return back to the fiber input end. Another method of three-dimensional imaging over single mode fibers was demonstrated in, using laser light of reduced spatial coherence. Coherence encoding, needed for a transmission of images by this methods, was realized with grating interferometer or with the help of an acousto-optic deflector. We suggest simple practical holographic method of image transmission over single multimode fiber or over fiber bundle with coherent light using filtering by holographic optical elements. Originally this method was successfully tested for the single multimode fiber. In this research we have modified holographic method for transmission of laser illuminated images over commercially available fiber bundle (fiber endoscope, or fiberscope).

Pain level after ACL reconstruction: A comparative study between free quadriceps tendon and hamstring tendons autografts.

PubMed

Buescu, Cristian Tudor; Onutu, Adela Hilda; Lucaciu, Dan Osvald; Todor, Adrian

2017-03-01

The objective of this study was to compare the pain levels and analgesic consumption after single bundle ACL reconstruction with free quadriceps tendon autograft versus hamstring tendon autograft. A total of 48 patients scheduled for anatomic single-bundle ACL reconstruction were randomized into two groups: the free quadriceps tendon autograft group (24 patients) and the hamstring tendons autograft group (24 patients). A basic multimodal analgesic postoperative program was used for all patients and rescue analgesia was provided with tramadol, at pain scores over 30 on the Visual Analog Scale. The time to the first rescue analgesic, the number of doses of tramadol and pain scores were recorded. The results within the same group were compared with the Wilcoxon signed test. Supplementary analgesic drug administration proved significantly higher in the group of subjects with hamstring grafts, with a median (interquartile range) of 1 (1.3) dose, compared to the group of subjects treated with a quadriceps graft, median = 0.5 (0.1.25) (p = 0.009). A significantly higher number of subjects with a quadriceps graft did not require any supplementary analgesic drug (50%) as compared with subjects with hamstring graft (13%; Z-statistics = 3.01, p = 0.002). The percentage of subjects who required a supplementary analgesic drug was 38% higher in the HT group compared with the FQT group. The use of the free quadriceps tendon autograft for ACL reconstruction leads to less pain and analgesic consumption in the immediate postoperative period compared with the use of hamstrings autograft. Level I Therapeutic study. Copyright © 2017 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

Development of a femoral template for computer-assisted tunnel placement in anatomical double-bundle ACL reconstruction.

PubMed

Luites, J W H; Wymenga, A B; Blankevoort, L; Kooloos, J M G; Verdonschot, N

2011-01-01

Femoral graft placement is an important factor in the success of anterior cruciate ligament (ACL) reconstruction. In addition to improving the accuracy of femoral tunnel placement, Computer Assisted Surgery (CAS) can be used to determine the anatomic location. This is achieved by using a 3D femoral template which indicates the position of the anatomical ACL center based on endoscopically measurable landmarks. This study describes the development and application of this method. The template is generated through statistical shape analysis of the ACL insertion, with respect to the anteromedial (AM) and posterolateral (PL) bundles. The ligament insertion data, together with the osteocartilage edge on the lateral notch, were mapped onto a cylinder fitted to the intercondylar notch surface (n = 33). Anatomic variation, in terms of standard variation of the positions of the ligament centers in the template, was within 2.2 mm. The resulting template was programmed in a computer-assisted navigation system for ACL replacement and its accuracy and precision were determined on 31 femora. It was found that with the navigation system the AM and PL tunnels could be positioned with an accuracy of 2.5 mm relative to the anatomic insertion centers; the precision was 2.4 mm. This system consists of a template that can easily be implemented in 3D computer navigation software. Requiring no preoperative images and planning, the system provides adequate accuracy and precision to position the entrance of the femoral tunnels for anatomical single- or double-bundle ACL reconstruction.

Volume and contact surface area analysis of bony tunnels in single and double bundle anterior cruciate ligament reconstruction using autograft tendons: in vivo three-dimensional imaging analysis.

PubMed

Yang, Jae-Hyuk; Chang, Minho; Kwak, Dai-Soon; Wang, Joon Ho

2014-09-01

Regarding reconstruction surgery of the anterior cruciate ligament (ACL), there is still a debate whether to perform a single bundle (SB) or double bundle (DB) reconstruction. The purpose of this study was to analyze and compare the volume and surface area of femoral and tibial tunnels during transtibial SB versus transportal DB ACL reconstruction. A consecutive series of 26 patients who underwent trantibial SB ACL reconstruction and 27 patients with transportal DB ACL reconstruction using hamstring autograft from January 2010 to October 2010 were included in this study. Three-dimensional computed tomography (3D-CT) was taken within one week after operation. The CT bone images were segmented with use of Mimics software v14.0. The obtained digital images were then imported in the commercial package Geomagic Studio v10.0 and SketchUp Pro v8.0 for processing. The femoral and tibial tunnel lengths, diameters, volumes and surface areas were evaluated. A comparison between the two groups was performed using the independent-samples t-test. A p-value less than the significance value of 5% (p < 0.05) was considered statistically significant. Regarding femur tunnels, a significant difference was not found between the tunnel volume for SB technique (1,496.51 ± 396.72 mm(3)) and the total tunnel volume for DB technique (1,593.81 ± 469.42 mm(3); p = 0.366). However, the total surface area for femoral tunnels was larger in DB technique (919.65 ± 201.79 mm(2)) compared to SB technique (810.02 ± 117.98 mm(2); p = 0.004). For tibia tunnels, there was a significant difference between tunnel volume for the SB technique (2,070.43 ± 565.07 mm(3)) and the total tunnel volume for the DB technique (2,681.93 ± 668.09 mm(3); p ≤ 0.001). The tibial tunnel surface area for the SB technique (958.84 ± 147.50 mm(2)) was smaller than the total tunnel surface area for the DB technique (1,493.31 ± 220.79 mm(2); p ≤ 0.001). Although the total femoral tunnel volume was similar between two techniques, the total surface area was larger in the DB technique. For the tibia, both total tunnel volume and the surface area were larger in DB technique.

ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION USING THE DOUBLE-BUNDLE TECHNIQUE – EVALUATION IN THE BIOMECHANICS LABORATORY

PubMed Central

D'Elia, Caio Oliveira; Bitar, Alexandre Carneiro; Castropil, Wagner; Garofo, Antônio Guilherme Padovani; Cantuária, Anita Lopes; Orselli, Maria Isabel Veras; Luques, Isabela Ugo; Duarte, Marcos

2015-01-01

Objective: The objective of this study was to describe the methodology of knee rotation analysis using biomechanics laboratory instruments and to present the preliminary results from a comparative study on patients who underwent anterior cruciate ligament (ACL) reconstruction using the double-bundle technique. Methods: The protocol currently used in our laboratory was described. Three-dimensional kinematic analysis was performed and knee rotation amplitude was measured on eight normal patients (control group) and 12 patients who were operated using the double-bundle technique, by means of three tasks in the biomechanics laboratory. Results: No significant differences between operated and non-operated sides were shown in relation to the mean amplitudes of gait, gait with change in direction or gait with change in direction when going down stairs (p > 0.13). Conclusion: The preliminary results did not show any difference in the double-bundle ACL reconstruction technique in relation to the contralateral side and the control group. PMID:27027003

Post-natal molecular adaptations in anteromedial and posterolateral bundles of the ovine anterior cruciate ligament: one structure with two parts or two distinct ligaments?

PubMed

Huebner, Kyla D; O'Brien, Etienne J O; Heard, Bryan J; Chung, May; Achari, Yamini; Shrive, Nigel G; Frank, Cyril B

2012-01-01

The human anterior cruciate ligament (ACL) is a composite structure of two anatomically distinct bundles: an anteromedial (AM) and posterolateral (PL) bundles. Tendons are often used as autografts for surgical reconstruction of ACL following severe injury. However, despite successful surgical reconstruction, some people experience re-rupture and later development of osteoarthritis. Understanding the structure and molecular makeup of normal ACL is essential for its optimal replacement. Reportedly the two bundles display different tensions throughout joint motion and may be fundamentally different. This study assessed the similarities and differences in ultrastructure and molecular composition of the AM and PL bundles to test the hypothesis that the two bundles of the ACL develop unique characteristics with maturation. ACLs from nine mature and six immature sheep were compared. The bundles were examined for mRNA and protein levels of collagen types I, III, V, and VI, and two proteoglycans. The fibril diameter composition of the two bundles was examined with transmission electron microscopy. Maturation does alter the molecular and structural composition of the two bundles of ACL. Although the PL band appears to mature slower than the AM band, no significant differences were detected between the bundles in the mature animals. We thus reject our hypothesis that the two ACL bundles are distinct. The two anatomically distinct bundles of the sheep ACL can be considered as two parts of one structure at maturity and material that would result in a structure of similar functionality can be used to replace each ACL bundle in the sheep.

Effective deep learning training for single-image super-resolution in endomicroscopy exploiting video-registration-based reconstruction.

PubMed

Ravì, Daniele; Szczotka, Agnieszka Barbara; Shakir, Dzhoshkun Ismail; Pereira, Stephen P; Vercauteren, Tom

2018-06-01

Probe-based confocal laser endomicroscopy (pCLE) is a recent imaging modality that allows performing in vivo optical biopsies. The design of pCLE hardware, and its reliance on an optical fibre bundle, fundamentally limits the image quality with a few tens of thousands fibres, each acting as the equivalent of a single-pixel detector, assembled into a single fibre bundle. Video registration techniques can be used to estimate high-resolution (HR) images by exploiting the temporal information contained in a sequence of low-resolution (LR) images. However, the alignment of LR frames, required for the fusion, is computationally demanding and prone to artefacts. In this work, we propose a novel synthetic data generation approach to train exemplar-based Deep Neural Networks (DNNs). HR pCLE images with enhanced quality are recovered by the models trained on pairs of estimated HR images (generated by the video registration algorithm) and realistic synthetic LR images. Performance of three different state-of-the-art DNNs techniques were analysed on a Smart Atlas database of 8806 images from 238 pCLE video sequences. The results were validated through an extensive image quality assessment that takes into account different quality scores, including a Mean Opinion Score (MOS). Results indicate that the proposed solution produces an effective improvement in the quality of the obtained reconstructed image. The proposed training strategy and associated DNNs allows us to perform convincing super-resolution of pCLE images.

Double-bundle anterior cruciate ligament reconstruction with and without remnant preservation - Comparison of early postoperative outcomes and complications.

PubMed

Nakayama, Hiroshi; Kambara, Syunichiro; Iseki, Tomoya; Kanto, Ryo; Kurosaka, Kenji; Yoshiya, Shinichi

2017-10-01

To compare the early postoperative outcomes and complications of double-bundle anterior cruciate ligament (ACL) reconstruction with and without remnant preservation. The study population comprised 125 consecutive knees that underwent double-bundle ACL reconstruction using hamstring autograft. Among the 125 knees, remnant preservation was indicated for 50 knees, while standard double-bundle reconstruction was performed in the remaining 75 knees. Postoperative evaluations included heel-height difference (HHD) at periodical follow-ups, number of knees requiring arthroscopic debridement due to problematic extension loss within six months, re-injury within one year, graft status upon second-look arthroscopy, and clinical examinations by Lysholm score and KT measurement at one year. All patients could be followed up for a minimum of one year after surgery. When the results obtained from both groups were compared, HHD values were significantly larger in the preservation group at three and six months, and the rate of knees requiring arthroscopic debridement was also higher in this group (12% versus 4.0%). Graft status on second-look arthroscopy was considered to be good for 92% of the knees in the preservation group versus 59% in the non-preservation group. Re-injury rates within one year were 2.0% in the preservation group and 5.3% in the non-preservation group. No significant differences in clinical examinations were found between the groups at one year. Remnant preservation in double-bundle hamstring autograft ACL reconstruction may enhance tissue healing; however, retention of the remnant with its full volume resulted in an increased incidence of postoperative problematic extension loss. Copyright © 2017 Elsevier B.V. All rights reserved.

Thomson scattering diagnostic on the Compact Toroidal Hybrid Experiment

NASA Astrophysics Data System (ADS)

Traverso, Peter; Maurer, D. A.; Ennis, D. A.; Hartwell, G. J.

2016-10-01

A Thomson scattering system is being commissioned for the non-axisymmetric plasmas of the Compact Toroidal Hybrid (CTH), a five-field period current-carrying torsatron. The system takes a single point measurement at the magnetic axis to both calibrate the two- color soft x-ray Te system and serve as an additional diagnostic for the V3FIT 3D equilibrium reconstruction code. A single point measurement will reduce the uncertainty in the reconstructed peak pressure by an order of magnitude for both current-carrying plasmas and future gyrotron-heated stellarator plasmas. The beam, generated by a frequency doubled Continuum 2 J, Nd:YaG laser, is passed vertically through an entrance Brewster window and a two-aperture optical baffle system to minimize stray light. The beam line propagates 8 m to the CTH device mid-plane with the beam diameter < 3 mm inside the plasma volume. Thomson scattered light is collected by two adjacent f/2 plano-convex condenser lenses and focused onto a custom fiber bundle. The fiber is then re-bundled and routed to a Holospec f/1.8 spectrograph to collect the red-shifted scattered light from 535-565 nm. The system has been designed to measure plasmas with core Te of 100 to 200 eV and densities of 5 ×1018 to 5 ×1019 m-3. Work supported by USDOE Grant DE-FG02-00ER54610.

Reliability of a semi-automated 3D-CT measuring method for tunnel diameters after anterior cruciate ligament reconstruction: A comparison between soft-tissue single-bundle allograft vs. autograft.

PubMed

Robbrecht, Cedric; Claes, Steven; Cromheecke, Michiel; Mahieu, Peter; Kakavelakis, Kyriakos; Victor, Jan; Bellemans, Johan; Verdonk, Peter

2014-10-01

Post-operative widening of tibial and/or femoral bone tunnels is a common observation after ACL reconstruction, especially with soft-tissue grafts. There are no studies comparing tunnel widening in hamstring autografts versus tibialis anterior allografts. The goal of this study was to observe the difference in tunnel widening after the use of allograft vs. autograft for ACL reconstruction, by measuring it with a novel 3-D computed tomography based method. Thirty-five ACL-deficient subjects were included, underwent anatomic single-bundle ACL reconstruction and were evaluated at one year after surgery with the use of 3-D CT imaging. Three independent observers semi-automatically delineated femoral and tibial tunnel outlines, after which a best-fit cylinder was derived and the tunnel diameter was determined. Finally, intra- and inter-observer reliability of this novel measurement protocol was defined. In femoral tunnels, the intra-observer ICC was 0.973 (95% CI: 0.922-0.991) and the inter-observer ICC was 0.992 (95% CI: 0.982-0.996). In tibial tunnels, the intra-observer ICC was 0.955 (95% CI: 0.875-0.985). The combined inter-observer ICC was 0.970 (95% CI: 0.987-0.917). Tunnel widening was significantly higher in allografts compared to autografts, in the tibial tunnels (p=0.013) as well as in the femoral tunnels (p=0.007). To our knowledge, this novel, semi-automated 3D-computed tomography image processing method has shown to yield highly reproducible results for the measurement of bone tunnel diameter and area. This series showed a significantly higher amount of tunnel widening observed in the allograft group at one-year follow-up. Level II, Prospective comparative study. Copyright © 2014 Elsevier B.V. All rights reserved.

Biomechanical differences of the anterior and posterior bands of the ulnar collateral ligament of the elbow.

PubMed

Jackson, Timothy J; Jarrell, Shelby E; Adamson, Gregory J; Chung, Kyung Chil; Lee, Thay Q

2016-07-01

The main purpose of this study was to examine the functional characteristics of the anterior and posterior bands of the anterior bundle of the ulnar collateral ligament (UCL). Six cadaveric elbows were tested using a digital tracking system to measure the strain in the anterior band and posterior band of the anterior bundle of the UCL throughout a flexion/extension arc. The specimens were then placed in an Instron materials testing machine and loaded to failure to determine yield load and ultimate load of the UCL. The posterior band showed a linear increase in strain with increasing degrees of elbow flexion while the anterior band showed minimal change in strain throughout. The bands showed similar strain at yield load and ultimate load, demonstrating similar intrinsic properties. The anterior band of the anterior bundle of the UCL shows an isometric strain pattern through elbow range of motion, while the posterior band shows an increasing strain pattern in higher degrees of elbow flexion. Both bands show similar strain in a load to failure model, indicating insertion point, not intrinsic differences, of the bands determine the function of the anterior bundle of the UCL. This demonstrates a biomechanical rationale for UCL reconstructions using single point anatomical insertion points.

Double-bundle PCL reconstruction using autologous hamstring tendons: outcome with a minimum 2-year follow-up.

PubMed

Cury, Ricardo de Paula Leite; Castro Filho, Rômulo Neves; Sadatsune, Daniel Akira; do Prado, Davi Ribeiro; Gonçalves, Ricardo José Peruzzo; Mestriner, Marcos Barbieri

2017-01-01

To present the outcomes of posterior cruciate ligament (PCL) double-bundle reconstruction using autologous hamstring tendons, with a minimum follow-up of two years. Evaluation of 16 cases of PCL injury that underwent double-bundle reconstruction with autogenous hamstring tendons, between 2011 and 2013. The final sample consisted of 16 patients, 15 men and one woman, with a mean age of 31 years (21-49). The predominant mechanism was motorcycle accident in half of the cases. There was a mean interval of 15 months between the time of lesion and the surgery (three to 52 months). Five lesions were isolated and 11, associated. Clinical evaluation, application of validated scores, and measurements with use of the KT-1000 were performed. The analysis showed a mean preoperative Lysholm score of 50 points (28-87), progressing to 94 points (85-100) postoperatively. The IKDC score also demonstrated improvement. In the preoperative evaluation, four and 12 patients were respectively classified as C (abnormal) and D (very unusual), and in the postoperative evaluation six as A (normal) and ten as B (close to normal). In the post-operative evaluation by KT1000 arthrometer, 13 patients showed difference between 0-2 mm and 3 between 3 and 5 mm, when compared with the contralateral side. Autologous hamstring tendons are a viable option in double-bundle reconstruction of the PCL, with good clinical results in a minimum follow-up of two years.

Review of evolution of tunnel position in anterior cruciate ligament reconstruction.

PubMed

Rayan, Faizal; Nanjayan, Shashi Kumar; Quah, Conal; Ramoutar, Darryl; Konan, Sujith; Haddad, Fares S

2015-03-18

Anterior cruciate ligament (ACL) rupture is one of the commonest knee sport injuries. The annual incidence of the ACL injury is between 100000-200000 in the United States. Worldwide around 400000 ACL reconstructions are performed in a year. The goal of ACL reconstruction is to restore the normal knee anatomy and kinesiology. The tibial and femoral tunnel placements are of primordial importance in achieving this outcome. Other factors that influence successful reconstruction are types of grafts, surgical techniques and rehabilitation programmes. A comprehensive understanding of ACL anatomy has led to the development of newer techniques supplemented by more robust biological and mechanical concepts. In this review we are mainly focussing on the evolution of tunnel placement in ACL reconstruction, focusing on three main categories, i.e., anatomical, biological and clinical outcomes. The importance of tunnel placement in the success of ACL reconstruction is well researched. Definite clinical and functional data is lacking to establish the superiority of the single or double bundle reconstruction technique. While there is a trend towards the use of anteromedial portals for femoral tunnel placement, their clinical superiority over trans-tibial tunnels is yet to be established.

Review of evolution of tunnel position in anterior cruciate ligament reconstruction

PubMed Central

Rayan, Faizal; Nanjayan, Shashi Kumar; Quah, Conal; Ramoutar, Darryl; Konan, Sujith; Haddad, Fares S

2015-01-01

Anterior cruciate ligament (ACL) rupture is one of the commonest knee sport injuries. The annual incidence of the ACL injury is between 100000-200000 in the United States. Worldwide around 400000 ACL reconstructions are performed in a year. The goal of ACL reconstruction is to restore the normal knee anatomy and kinesiology. The tibial and femoral tunnel placements are of primordial importance in achieving this outcome. Other factors that influence successful reconstruction are types of grafts, surgical techniques and rehabilitation programmes. A comprehensive understanding of ACL anatomy has led to the development of newer techniques supplemented by more robust biological and mechanical concepts. In this review we are mainly focussing on the evolution of tunnel placement in ACL reconstruction, focusing on three main categories, i.e., anatomical, biological and clinical outcomes. The importance of tunnel placement in the success of ACL reconstruction is well researched. Definite clinical and functional data is lacking to establish the superiority of the single or double bundle reconstruction technique. While there is a trend towards the use of anteromedial portals for femoral tunnel placement, their clinical superiority over trans-tibial tunnels is yet to be established. PMID:25793165

One-stage Revision ACL reconstruction with hamstring autograft results in satisfactory outcome

PubMed Central

Kejriwal, Ritwik; Buelow, Jens

2017-01-01

Objectives: Revision anterior cruciate ligament (ACL) reconstruction is associated with poorer outcomes and higher rerupture rates when compared to primary ACL reconstruction. There is also a significant heterogeneity in surgical technique, number of stages, and graft options. We report a large single surgeon case series with hamstring autograft as a graft option. Methods: Observational series of revision ACL reconstructions performed by the senior author between 2005 and 2015 was carried out. Chart reviews and clinic follow-ups were performed with the following recorded – re-rupture rate, radiographic grading of osteoarthritis, KT-1000 arthrometer test, IKDC outcome scores and knee range of motion. All patients underwent single bundle four-strand hamstring autograft performed in one stage with use of new tunnels in majority of the cases. Results: 66 patients underwent hamstring autograft one-stage revision ACL reconstruction by Dr Jens Buelow. Chart review was carried out on all patients, and 26 (39%) were followed up in clinic and/or by phone with a mean follow up of 4.7 years. Outcomes included re-rupture rate of 4.5%, reoperation rate of 12%, mean visual analogue scale score of 7.6, mean side-to-side difference of 2.6 mm for KT-1000 arthrometer test, and mean IKDC score of 79. Of the 17 patients with radiographs, 40% had moderate osteoarthritis (grade 2 or 3) at follow-up. Conclusion: Revision ACL reconstruction can result in a satisfactory outcome when performed with a hamstring autograft in one stage.

Magnetopause Transects

NASA Technical Reports Server (NTRS)

Sonnerup, B. U. O; Guo, M.

1996-01-01

A novel method is described for reconstruction of two-dimensional current-layer structures from measurements taken by a single spacecraft traversing the layer. In its present form, the method is applicable only to 2D magnetohydrostatic structures that are passively convected past the observing spacecraft. It is tested on a magnetopause crossing of the tangential-discontinuity type by the spacecraft AMPTE/IRM. The magnetic structures recovered include a magnetic island located between two X-type nulls as well as a magnetic 'worm hole' through which a bundle of weak magnetic flux appears to connect the magnetosphere and the magnetosheath.

Magnetopause transects

NASA Astrophysics Data System (ADS)

Sonnerup, B. U. Ö.; Guo, M.

A novel method is described for reconstruction of two-dimensional current-layer structures from measurements taken by a single spacecraft traversing the layer. In its present form, the method is applicable only to 2D magneto-hydrostatic structures that are passively convected past the observing spacecraft. It is tested on a magnetopause crossing of the tangential-discontinuity type by the spacecraft AMPTE/IRM. The magnetic structures recovered include a magnetic island located between two X-type nulls as well as a magnetic ‘worm hole’ through which a bundle of weak magnetic flux appears to connect the magnetosphere and the magnetosheath.

Automated retinofugal visual pathway reconstruction with multi-shell HARDI and FOD-based analysis.

PubMed

Kammen, Alexandra; Law, Meng; Tjan, Bosco S; Toga, Arthur W; Shi, Yonggang

2016-01-15

Diffusion MRI tractography provides a non-invasive modality to examine the human retinofugal projection, which consists of the optic nerves, optic chiasm, optic tracts, the lateral geniculate nuclei (LGN) and the optic radiations. However, the pathway has several anatomic features that make it particularly challenging to study with tractography, including its location near blood vessels and bone-air interface at the base of the cerebrum, crossing fibers at the chiasm, somewhat-tortuous course around the temporal horn via Meyer's Loop, and multiple closely neighboring fiber bundles. To date, these unique complexities of the visual pathway have impeded the development of a robust and automated reconstruction method using tractography. To overcome these challenges, we develop a novel, fully automated system to reconstruct the retinofugal visual pathway from high-resolution diffusion imaging data. Using multi-shell, high angular resolution diffusion imaging (HARDI) data, we reconstruct precise fiber orientation distributions (FODs) with high order spherical harmonics (SPHARM) to resolve fiber crossings, which allows the tractography algorithm to successfully navigate the complicated anatomy surrounding the retinofugal pathway. We also develop automated algorithms for the identification of ROIs used for fiber bundle reconstruction. In particular, we develop a novel approach to extract the LGN region of interest (ROI) based on intrinsic shape analysis of a fiber bundle computed from a seed region at the optic chiasm to a target at the primary visual cortex. By combining automatically identified ROIs and FOD-based tractography, we obtain a fully automated system to compute the main components of the retinofugal pathway, including the optic tract and the optic radiation. We apply our method to the multi-shell HARDI data of 215 subjects from the Human Connectome Project (HCP). Through comparisons with post-mortem dissection measurements, we demonstrate the retinotopic organization of the optic radiation including a successful reconstruction of Meyer's loop. Then, using the reconstructed optic radiation bundle from the HCP cohort, we construct a probabilistic atlas and demonstrate its consistency with a post-mortem atlas. Finally, we generate a shape-based representation of the optic radiation for morphometry analysis. Copyright © 2015 Elsevier Inc. All rights reserved.

Proximal tibial fracture following anterior cruciate ligament reconstruction surgery: a biomechanical analysis of the tibial tunnel as a stress riser.

PubMed

Aldebeyan, Wassim; Liddell, Antony; Steffen, Thomas; Beckman, Lorne; Martineau, Paul A

2017-08-01

This is the first biomechanical study to examine the potential stress riser effect of the tibial tunnel or tunnels after ACL reconstruction surgery. In keeping with literature, the primary hypothesis tested in this study was that the tibial tunnel acts as a stress riser for fracture propagation. Secondary hypotheses were that the stress riser effect increases with the size of the tunnel (8 vs. 10 mm), the orientation of the tunnel [standard (STT) vs. modified transtibial (MTT)], and with the number of tunnels (1 vs. 2). Tibial tunnels simulating both single bundle hamstring graft (8 mm) and bone-patellar tendon-bone graft (10 mm) either STT or MTT position, as well as tunnels simulating double bundle (DB) ACL reconstruction (7, 6 mm), were drilled in fourth-generation saw bones. These five experimental groups and a control group consisting of native saw bones without tunnels were loaded to failure on a Materials Testing System to simulate tibial plateau fracture. There were no statistically significant differences in peak load to failure between any of the groups, including the control group. The fracture occurred through the tibial tunnel in 100 % of the MTT tunnels (8 and 10 mm) and 80 % of the DB tunnels specimens; however, the fractures never (0 %) occurred through the tibial tunnel of the standard tunnels (8 or 10 mm) (P = 0.032). In the biomechanical model, the tibial tunnel does not appear to be a stress riser for fracture propagation, despite suggestions to the contrary in the literature. Use of a standard, more vertical tunnel decreases the risk of ACL graft compromise in the event of a fracture. This may help to inform surgical decision making on ACL reconstruction technique.

Fiber bundle endomicroscopy with multi-illumination for three-dimensional reflectance image reconstruction

NASA Astrophysics Data System (ADS)

Ando, Yoriko; Sawahata, Hirohito; Kawano, Takeshi; Koida, Kowa; Numano, Rika

2018-02-01

Bundled fiber optics allow in vivo imaging at deep sites in a body. The intrinsic optical contrast detects detailed structures in blood vessels and organs. We developed a bundled-fiber-coupled endomicroscope, enabling stereoscopic three-dimensional (3-D) reflectance imaging with a multipositional illumination scheme. Two illumination sites were attached to obtain reflectance images with left and right illumination. Depth was estimated by the horizontal disparity between the two images under alternative illuminations and was calibrated by the targets with known depths. This depth reconstruction was applied to an animal model to obtain the 3-D structure of blood vessels of the cerebral cortex (Cereb cortex) and preputial gland (Pre gla). The 3-D endomicroscope could be instrumental to microlevel reflectance imaging, improving the precision in subjective depth perception, spatial orientation, and identification of anatomical structures.

Easy-DHPSF open-source software for three-dimensional localization of single molecules with precision beyond the optical diffraction limit.

PubMed

Lew, Matthew D; von Diezmann, Alexander R S; Moerner, W E

2013-02-25

Automated processing of double-helix (DH) microscope images of single molecules (SMs) streamlines the protocol required to obtain super-resolved three-dimensional (3D) reconstructions of ultrastructures in biological samples by single-molecule active control microscopy. Here, we present a suite of MATLAB subroutines, bundled with an easy-to-use graphical user interface (GUI), that facilitates 3D localization of single emitters (e.g. SMs, fluorescent beads, or quantum dots) with precisions of tens of nanometers in multi-frame movies acquired using a wide-field DH epifluorescence microscope. The algorithmic approach is based upon template matching for SM recognition and least-squares fitting for 3D position measurement, both of which are computationally expedient and precise. Overlapping images of SMs are ignored, and the precision of least-squares fitting is not as high as maximum likelihood-based methods. However, once calibrated, the algorithm can fit 15-30 molecules per second on a 3 GHz Intel Core 2 Duo workstation, thereby producing a 3D super-resolution reconstruction of 100,000 molecules over a 20×20×2 μm field of view (processing 128×128 pixels × 20000 frames) in 75 min.

Inferring segmented dense motion layers using 5D tensor voting.

PubMed

Min, Changki; Medioni, Gérard

2008-09-01

We present a novel local spatiotemporal approach to produce motion segmentation and dense temporal trajectories from an image sequence. A common representation of image sequences is a 3D spatiotemporal volume, (x,y,t), and its corresponding mathematical formalism is the fiber bundle. However, directly enforcing the spatiotemporal smoothness constraint is difficult in the fiber bundle representation. Thus, we convert the representation into a new 5D space (x,y,t,vx,vy) with an additional velocity domain, where each moving object produces a separate 3D smooth layer. The smoothness constraint is now enforced by extracting 3D layers using the tensor voting framework in a single step that solves both correspondence and segmentation simultaneously. Motion segmentation is achieved by identifying those layers, and the dense temporal trajectories are obtained by converting the layers back into the fiber bundle representation. We proceed to address three applications (tracking, mosaic, and 3D reconstruction) that are hard to solve from the video stream directly because of the segmentation and dense matching steps, but become straightforward with our framework. The approach does not make restrictive assumptions about the observed scene or camera motion and is therefore generally applicable. We present results on a number of data sets.

Tibial tunnel aperture location during single-bundle posterior cruciate ligament reconstruction: comparison of tibial guide positions.

PubMed

Shin, Young-Soo; Han, Seung-Beom; Hwang, Yeok-Ku; Suh, Dong-Won; Lee, Dae-Hee

2015-05-01

We aimed to compare posterior cruciate ligament (PCL) tibial tunnel location after tibial guide insertion medial (between the PCL remnant and the medial femoral condyle) and lateral (between the PCL remnant and the anterior cruciate ligament) to the PCL stump as determined by in vivo 3-dimensional computed tomography (3D-CT). Tibial tunnel aperture location was analyzed by immediate postoperative in vivo CT in 66 patients who underwent single-bundle PCL reconstruction, 31 by over-the-PCL and 35 by under-the-PCL tibial guide insertion techniques. Tibial tunnel positions were measured in the medial to lateral and proximal to distal directions of the posterior proximal tibia. The center of the tibial tunnel aperture was located more laterally (by 2.7 mm) in the over-the-PCL group than in the under-the-PCL group (P = .040) and by a relative percentage (absolute value/tibial width) of 3.2% (P = .031). Tibial tunnel positions in the proximal to distal direction, determined by absolute value and relative percentage, were similar in the 2 groups. Tibial tunnel apertures were located more laterally after lateral-to-the-PCL tibial guide insertion than after medial-to-the-PCL tibial guide insertion. There was, however, no significant difference between these techniques in distance from the joint line to the tibial tunnel aperture. Insertion lateral to the PCL stump may result in better placement of the PCL in its anatomic footprint. Level III, retrospective comparative study. Copyright © 2015 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Evaluating the distance between the femoral tunnel centers in anatomic double-bundle anterior cruciate ligament reconstruction using a computer simulation

PubMed Central

Tashiro, Yasutaka; Okazaki, Ken; Iwamoto, Yukihide

2015-01-01

Purpose We aimed to clarify the distance between the anteromedial (AM) bundle and posterolateral (PL) bundle tunnel-aperture centers by simulating the anatomical femoral tunnel placement during double-bundle anterior cruciate ligament reconstruction using 3-D computer-aided design models of the knee, in order to discuss the risk of tunnel overlap. Relationships between the AM to PL center distance, body height, and sex difference were also analyzed. Patients and methods The positions of the AM and PL tunnel centers were defined based on previous studies using the quadrant method, and were superimposed anatomically onto the 3-D computer-aided design knee models from 68 intact femurs. The distance between the tunnel centers was measured using the 3-D DICOM software package. The correlation between the AM–PL distance and the subject’s body height was assessed, and a cutoff height value for a higher risk of overlap of the AM and PL tunnel apertures was identified. Results The distance between the AM and PL centers was 10.2±0.6 mm in males and 9.4±0.5 mm in females (P<0.01). The AM–PL center distance demonstrated good correlation with body height in both males (r=0.66, P<0.01) and females (r=0.63, P<0.01). When 9 mm was defined as the critical distance between the tunnel centers to preserve a 2 mm bony bridge between the two tunnels, the cutoff value was calculated to be a height of 160 cm in males and 155 cm in females. Conclusion When AM and PL tunnels were placed anatomically in simulated double-bundle anterior cruciate ligament reconstruction, the distance between the two tunnel centers showed a strong positive correlation with body height. In cases with relatively short stature, the AM and PL tunnel apertures are considered to be at a higher risk of overlap when surgeons choose the double-bundle technique. PMID:26170727

Quantitative study of bundle size effect on thermal conductivity of single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Feng, Ya; Inoue, Taiki; An, Hua; Xiang, Rong; Chiashi, Shohei; Maruyama, Shigeo

2018-05-01

Compared with isolated single-walled carbon nanotubes (SWNTs), thermal conductivity is greatly impeded in SWNT bundles; however, the measurement of the bundle size effect is difficult. In this study, the number of SWNTs in a bundle was determined based on the transferred horizontally aligned SWNTs on a suspended micro-thermometer to quantitatively study the effect of the bundle size on thermal conductivity. Increasing the bundle size significantly degraded the thermal conductivity. For isolated SWNTs, thermal conductivity was approximately 5000 ± 1000 W m-1 K-1 at room temperature, three times larger than that of the four-SWNT bundle. The logarithmical deterioration of thermal conductivity resulting from the increased bundle size can be attributed to the increased scattering rate with neighboring SWNTs based on the kinetic theory.

Methods of reconstruction of multi-particle events in the new coordinate-tracking setup

NASA Astrophysics Data System (ADS)

Vorobyev, V. S.; Shutenko, V. V.; Zadeba, E. A.

2018-01-01

At the Unique Scientific Facility NEVOD (MEPhI), a large coordinate-tracking detector based on drift chambers for investigations of muon bundles generated by ultrahigh energy primary cosmic rays is being developed. One of the main characteristics of the bundle is muon multiplicity. Three methods of reconstruction of multiple events were investigated: the sequential search method, method of finding the straight line and method of histograms. The last method determines the number of tracks with the same zenith angle in the event. It is most suitable for the determination of muon multiplicity: because of a large distance to the point of generation of muons, their trajectories are quasiparallel. The paper presents results of application of three reconstruction methods to data from the experiment, and also first results of the detector operation.

Complications and Adverse Events of a Randomized Clinical Trial Comparing 3 Graft Types for ACL Reconstruction.

PubMed

Mohtadi, Nicholas; Barber, Rhamona; Chan, Denise; Paolucci, Elizabeth Oddone

2016-05-01

Complications/adverse events of anterior cruciate ligament (ACL) surgery are underreported, despite pooled level 1 data in systematic reviews. All adverse events/complications occurring within a 2-year postoperative period after primary ACL reconstruction, as part of a large randomized clinical trial (RCT), were identified and described. Prospective, double-blind randomized clinical trial. Patients and the independent trained examiner were blinded to treatment allocation. University-based orthopedic referral practice. Three hundred thirty patients (14-50 years; 183 males) with isolated ACL deficiency were intraoperatively randomized to ACL reconstruction with 1 autograft type. Graft harvest and arthroscopic portal incisions were identical. Patients were equally distributed to patellar tendon (PT), quadruple-stranded hamstring tendon (HT), and double-bundle (DB) hamstring autograft ACL reconstruction. Adverse events/complications were patient reported, documented, and diagnoses confirmed. Two major complications occurred: pulmonary embolism and septic arthritis. Twenty-four patients (7.3%) required repeat surgery, including 25 separate operations: PT = 7 (6.4%), HT = 9 (8.2%), and DB = 8 (7.3%). Repeat surgery was performed for meniscal tears (3.6%; n = 12), intra-articular scarring (2.7%; n = 9), chondral pathology (0.6%; n = 2), and wound dehiscence (0.3%; n = 1). Other complications included wound problems, sensory nerve damage, muscle tendon injury, tibial periostitis, and suspected meniscal tears and chondral lesions. Overall, more complications occurred in the HT/DB groups (PT = 24; HT = 31; DB = 45), but more PT patients complained of moderate or severe kneeling pain (PT = 17; HT = 9; DB = 4) at 2 years. Overall, ACL reconstructive surgery is safe. Major complications were uncommon. Secondary surgery was necessary 7.3% of the time for complications/adverse events (excluding graft reinjury or revisions) within the first 2 years. Level 1 (therapeutic studies). This article reports on the complications/adverse events that were prospectively identified up to 2 years postoperatively, in a defined patient population participating in a large double-blind randomized clinical trial comparing PT, single-bundle hamstring, and DB hamstring reconstructions for ACL rupture.

Morphologic and hydrodynamic controls on the occurrence of tidal bundles in an open-coast macrotidal environment, northern Gyeonggi Bay, west coast of Korea

NASA Astrophysics Data System (ADS)

Choi, Kyungsik; Kim, Do Hyeong

2016-06-01

Tidal dunes with well-defined rhythmic tidal bundles are documented from the lower intertidal zone of an open-coast macrotidal environment in Gyeonggi Bay, Korea. Based on combined morphologic, sedimentologic and hydrodynamic datasets, this study aims to characterize the factors that govern the temporal and spatial variability of tidal bundles in a non-barred, unconfined macrotidal environment. The tidal dunes are flood-asymmetric and of longer wavelength (10-20 m) with small ebb caps on the upper bank, and symmetric to slightly ebb-asymmetric and of shorter wavelength (5-10 m) with larger ebb caps on the lower bank. The upper-bank dunes are characterized by more steeply dipping flood-directed planar cross-beds and thinner mud drapes than the lower-bank dunes. Each tidal bundle consists of a single mud drape that is stratified to cross-stratified, rich in silt and very fine sand. It overlies ebb-directed ripples and represents dynamic mud deposition during the ebb tidal phase. The presence of strong rotary currents (up to 0.25 m/s) and low suspended-sediment concentration of flood currents prevent deposition of mud drapes during the high-tide slack-water period. The distinct asymmetry in the water elevation at which the velocity peaks during the ebb and flood phases results in the preferential preservation of flood-directed cross-beds in the lower intertidal zone, where the ebb current - although stronger than the flood currents - is of shorter duration and hence unable to reverse the dune profile. The pronounced time-velocity asymmetry at the higher elevation combined with the distinct velocity peak asymmetry leads to a better preservation of hierarchical tidal cycles in the upper-bank dunes. The present study suggests that the persistent occurrence of single, stratified to cross-stratified mud drapes, which reflect dynamic mud deposition during the ebb phase, and the dominance of flood-directed cross-beds are diagnostic features of tidal bundles in the intertidal zone of unbarred, open-coast macrotidal environments. A proposed model for mud drape deposition provides a new perspective on the origin of tidal bundles together with useful criteria for reconstructing the paleo-depositional setting.

Actualizing Flexible National Security Space Systems

DTIC Science & Technology

2011-01-01

single launch vehicle is a decision unique to small satellites that adds an extra dimension to the launch risk calculation. While bundling...following a launch failure. The ability to bundle multiple payloads on a single launch vehicle is a decision unique to small satellites that adds an extra ... dimension to the launch risk calculation. While bundling multiple small satellites on a single launch vehicle spreads the initial launch cost across

Relationships Between Tibiofemoral Contact Forces and Cartilage Morphology at 2 to 3 Years After Single-Bundle Hamstring Anterior Cruciate Ligament Reconstruction and in Healthy Knees.

PubMed

Saxby, David John; Bryant, Adam L; Wang, Xinyang; Modenese, Luca; Gerus, Pauline; Konrath, Jason M; Bennell, Kim L; Fortin, Karine; Wrigley, Tim; Cicuttini, Flavia M; Vertullo, Christopher J; Feller, Julian A; Whitehead, Tim; Gallie, Price; Lloyd, David G

2017-08-01

Prevention of knee osteoarthritis (OA) following anterior cruciate ligament (ACL) rupture and reconstruction is vital. Risk of postreconstruction knee OA is markedly increased by concurrent meniscal injury. It is unclear whether reconstruction results in normal relationships between tibiofemoral contact forces and cartilage morphology and whether meniscal injury modulates these relationships. Since patients with isolated reconstructions (ie, without meniscal injury) are at lower risk for knee OA, we predicted that relationships between tibiofemoral contact forces and cartilage morphology would be similar to those of normal, healthy knees 2 to 3 years postreconstruction. In knees with meniscal injuries, these relationships would be similar to those reported in patients with knee OA, reflecting early degenerative changes. Cross-sectional study; Level of evidence, 3. Three groups were examined: (1) 62 patients who received single-bundle hamstring reconstruction with an intact, uninjured meniscus (mean age, 29.8 ± 6.4 years; mean weight, 74.9 ± 13.3 kg); (2) 38 patients with similar reconstruction with additional meniscal injury (ie, tear, repair) or partial resection (mean age, 30.6 ± 6.6 years; mean weight, 83.3 ± 14.3 kg); and (3) 30 ligament-normal, healthy individuals (mean age, 28.3 ± 5.2 years; mean weight, 74.9 ± 14.9 kg) serving as controls. All patients underwent magnetic resonance imaging to measure the medial and lateral tibial articular cartilage morphology (volumes and thicknesses). An electromyography-driven neuromusculoskeletal model determined medial and lateral tibiofemoral contact forces during walking. General linear models were used to assess relationships between tibiofemoral contact forces and cartilage morphology. In control knees, cartilage was thicker compared with that of isolated and meniscal-injured ACL-reconstructed knees, while greater contact forces were related to both greater tibial cartilage volumes (medial: R 2 = 0.43, β = 0.62, P = .000; lateral: R 2 = 0.19, β = 0.46, P = .03) and medial thicknesses ( R 2 = 0.24, β = 0.48, P = .01). In the overall group of ACL-reconstructed knees, greater contact forces were related to greater lateral cartilage volumes ( R 2 = 0.08, β = 0.28, P = .01). In ACL-reconstructed knees with lateral meniscal injury, greater lateral contact forces were related to greater lateral cartilage volumes ( R 2 = 0.41, β = 0.64, P = .001) and thicknesses ( R 2 = 0.20, β = 0.46, P = .04). At 2 to 3 years postsurgery, ACL-reconstructed knees had thinner cartilage compared with healthy knees, and there were no positive relationships between medial contact forces and cartilage morphology. In lateral meniscal-injured reconstructed knees, greater contact forces were related to greater lateral cartilage volumes and thicknesses, although it was unclear whether this was an adaptive response or associated with degeneration. Future clinical studies may seek to establish whether cartilage morphology can be modified through rehabilitation programs targeting contact forces directly in addition to the current rehabilitation foci of restoring passive and dynamic knee range of motion, knee strength, and functional performance.

Relationships Between Tibiofemoral Contact Forces and Cartilage Morphology at 2 to 3 Years After Single-Bundle Hamstring Anterior Cruciate Ligament Reconstruction and in Healthy Knees

PubMed Central

Saxby, David John; Bryant, Adam L.; Wang, Xinyang; Modenese, Luca; Gerus, Pauline; Konrath, Jason M.; Bennell, Kim L.; Fortin, Karine; Wrigley, Tim; Cicuttini, Flavia M.; Vertullo, Christopher J.; Feller, Julian A.; Whitehead, Tim; Gallie, Price; Lloyd, David G.

2017-01-01

Background: Prevention of knee osteoarthritis (OA) following anterior cruciate ligament (ACL) rupture and reconstruction is vital. Risk of postreconstruction knee OA is markedly increased by concurrent meniscal injury. It is unclear whether reconstruction results in normal relationships between tibiofemoral contact forces and cartilage morphology and whether meniscal injury modulates these relationships. Hypotheses: Since patients with isolated reconstructions (ie, without meniscal injury) are at lower risk for knee OA, we predicted that relationships between tibiofemoral contact forces and cartilage morphology would be similar to those of normal, healthy knees 2 to 3 years postreconstruction. In knees with meniscal injuries, these relationships would be similar to those reported in patients with knee OA, reflecting early degenerative changes. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Three groups were examined: (1) 62 patients who received single-bundle hamstring reconstruction with an intact, uninjured meniscus (mean age, 29.8 ± 6.4 years; mean weight, 74.9 ± 13.3 kg); (2) 38 patients with similar reconstruction with additional meniscal injury (ie, tear, repair) or partial resection (mean age, 30.6 ± 6.6 years; mean weight, 83.3 ± 14.3 kg); and (3) 30 ligament-normal, healthy individuals (mean age, 28.3 ± 5.2 years; mean weight, 74.9 ± 14.9 kg) serving as controls. All patients underwent magnetic resonance imaging to measure the medial and lateral tibial articular cartilage morphology (volumes and thicknesses). An electromyography-driven neuromusculoskeletal model determined medial and lateral tibiofemoral contact forces during walking. General linear models were used to assess relationships between tibiofemoral contact forces and cartilage morphology. Results: In control knees, cartilage was thicker compared with that of isolated and meniscal-injured ACL-reconstructed knees, while greater contact forces were related to both greater tibial cartilage volumes (medial: R 2 = 0.43, β = 0.62, P = .000; lateral: R 2 = 0.19, β = 0.46, P = .03) and medial thicknesses (R 2 = 0.24, β = 0.48, P = .01). In the overall group of ACL-reconstructed knees, greater contact forces were related to greater lateral cartilage volumes (R 2 = 0.08, β = 0.28, P = .01). In ACL-reconstructed knees with lateral meniscal injury, greater lateral contact forces were related to greater lateral cartilage volumes (R 2 = 0.41, β = 0.64, P = .001) and thicknesses (R 2 = 0.20, β = 0.46, P = .04). Conclusion: At 2 to 3 years postsurgery, ACL-reconstructed knees had thinner cartilage compared with healthy knees, and there were no positive relationships between medial contact forces and cartilage morphology. In lateral meniscal-injured reconstructed knees, greater contact forces were related to greater lateral cartilage volumes and thicknesses, although it was unclear whether this was an adaptive response or associated with degeneration. Future clinical studies may seek to establish whether cartilage morphology can be modified through rehabilitation programs targeting contact forces directly in addition to the current rehabilitation foci of restoring passive and dynamic knee range of motion, knee strength, and functional performance. PMID:28894756

Dipy, a library for the analysis of diffusion MRI data.

PubMed

Garyfallidis, Eleftherios; Brett, Matthew; Amirbekian, Bagrat; Rokem, Ariel; van der Walt, Stefan; Descoteaux, Maxime; Nimmo-Smith, Ian

2014-01-01

Diffusion Imaging in Python (Dipy) is a free and open source software project for the analysis of data from diffusion magnetic resonance imaging (dMRI) experiments. dMRI is an application of MRI that can be used to measure structural features of brain white matter. Many methods have been developed to use dMRI data to model the local configuration of white matter nerve fiber bundles and infer the trajectory of bundles connecting different parts of the brain. Dipy gathers implementations of many different methods in dMRI, including: diffusion signal pre-processing; reconstruction of diffusion distributions in individual voxels; fiber tractography and fiber track post-processing, analysis and visualization. Dipy aims to provide transparent implementations for all the different steps of dMRI analysis with a uniform programming interface. We have implemented classical signal reconstruction techniques, such as the diffusion tensor model and deterministic fiber tractography. In addition, cutting edge novel reconstruction techniques are implemented, such as constrained spherical deconvolution and diffusion spectrum imaging (DSI) with deconvolution, as well as methods for probabilistic tracking and original methods for tractography clustering. Many additional utility functions are provided to calculate various statistics, informative visualizations, as well as file-handling routines to assist in the development and use of novel techniques. In contrast to many other scientific software projects, Dipy is not being developed by a single research group. Rather, it is an open project that encourages contributions from any scientist/developer through GitHub and open discussions on the project mailing list. Consequently, Dipy today has an international team of contributors, spanning seven different academic institutions in five countries and three continents, which is still growing.

Dipy, a library for the analysis of diffusion MRI data

PubMed Central

Garyfallidis, Eleftherios; Brett, Matthew; Amirbekian, Bagrat; Rokem, Ariel; van der Walt, Stefan; Descoteaux, Maxime; Nimmo-Smith, Ian

2014-01-01

Diffusion Imaging in Python (Dipy) is a free and open source software project for the analysis of data from diffusion magnetic resonance imaging (dMRI) experiments. dMRI is an application of MRI that can be used to measure structural features of brain white matter. Many methods have been developed to use dMRI data to model the local configuration of white matter nerve fiber bundles and infer the trajectory of bundles connecting different parts of the brain. Dipy gathers implementations of many different methods in dMRI, including: diffusion signal pre-processing; reconstruction of diffusion distributions in individual voxels; fiber tractography and fiber track post-processing, analysis and visualization. Dipy aims to provide transparent implementations for all the different steps of dMRI analysis with a uniform programming interface. We have implemented classical signal reconstruction techniques, such as the diffusion tensor model and deterministic fiber tractography. In addition, cutting edge novel reconstruction techniques are implemented, such as constrained spherical deconvolution and diffusion spectrum imaging (DSI) with deconvolution, as well as methods for probabilistic tracking and original methods for tractography clustering. Many additional utility functions are provided to calculate various statistics, informative visualizations, as well as file-handling routines to assist in the development and use of novel techniques. In contrast to many other scientific software projects, Dipy is not being developed by a single research group. Rather, it is an open project that encourages contributions from any scientist/developer through GitHub and open discussions on the project mailing list. Consequently, Dipy today has an international team of contributors, spanning seven different academic institutions in five countries and three continents, which is still growing. PMID:24600385

SU-E-J-128: 3D Surface Reconstruction of a Patient Using Epipolar Geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kotoku, J; Nakabayashi, S; Kumagai, S

Purpose: To obtain a 3D surface data of a patient in a non-invasive way can substantially reduce the effort for the registration of patient in radiation therapy. To achieve this goal, we introduced the multiple view stereo technique, which is known to be used in a 'photo tourism' on the internet. Methods: 70 Images were taken with a digital single-lens reflex camera from different angles and positions. The camera positions and angles were inferred later in the reconstruction step. A sparse 3D reconstruction model was locating by SIFT features, which is robust for rotation and shift variance, in each image.more » We then found a set of correspondences between pairs of images by computing the fundamental matrix using the eight-point algorithm with RANSAC. After the pair matching, we optimized the parameter including camera positions to minimize the reprojection error by use of bundle adjustment technique (non-linear optimization). As a final step, we performed dense reconstruction and associate a color with each point using the library of PMVS. Results: Surface data were reconstructed well by visual inspection. The human skin is reconstructed well, althogh the reconstruction was time-consuming for direct use in daily clinical practice. Conclusion: 3D reconstruction using multi view stereo geometry is a promising tool for reducing the effort of patient setup. This work was supported by JSPS KAKENHI(25861128)« less

Knee rotation influences the femoral tunnel angle measurement after anterior cruciate ligament reconstruction: a 3-dimensional computed tomography model study

PubMed Central

Tang, Jing; Thorhauer, Eric; Marsh, Chelsea; Fu, Freddie H.

2013-01-01

Purpose Femoral tunnel angle (FTA) has been proposed as a metric for evaluating whether ACL reconstruction was performed anatomically. In clinic, radiographic images are typically acquired with an uncertain amount of internal/external knee rotation. The extent to which knee rotation will influence FTA measurement is unclear. Furthermore, differences in FTA measurement between the two common positions (0° and 45° knee flexion) have not been established. The purpose of this study was to investigate the influence of knee rotation on FTA measurement after ACL reconstruction. Methods Knee CT data from 16 subjects were segmented to produce 3D bone models. Central axes of tunnels were identified. The 0° and 45° flexion angles were simulated. Knee internal/external rotations were simulated in a range of ±20°. FTA was defined as the angle between the tunnel axis and femoral shaft axis, orthogonally projected into the coronal plane. Results Femoral tunnel angle was positively/negatively correlated with knee rotation angle at 0°/45° knee flexion. At 0° knee flexion, FTA for anterio-medial (AM) tunnels was significantly decreased at 20° of external knee rotation. At 45° knee flexion, more than 16° external or 19° internal rotation significantly altered FTA measurements for single-bundle tunnels; smaller rotations (±9° for AM, ±5° for PL) created significant errors in FTA measurements after double-bundle reconstruction. Conclusion Femoral tunnel angle measurements were correlated with knee rotation. Relatively small imaging malalignment introduced significant errors with knee flexed 45°. This study supports using the 0° flexion position for knee radiographs to reduce errors in FTA measurement due to knee internal/external rotation. Level of evidence Case–control study, Level III. PMID:23589127

Specific compartmental analysis of cartilage status in double-bundle ACL reconstruction patients: a comparative study using pre- and postoperative MR images.

PubMed

Lee, Yong Seuk; Jeong, Yu Mi; Sim, Jae Ang; Kwak, Ji Hoon; Kim, Kwang Hee; Nam, Shin Woo; Lee, Beom Koo

2013-03-01

The purpose of this study was to evaluate the changes in the site-specific cartilage status after a double-bundle ACL reconstruction using preoperative and follow-up MR images. Thirty-six knees that underwent a double-bundle ACL reconstruction from 2001 to 2009 with the available preoperative and follow-up magnetic resonance imaging were included. Patients with a meniscal injury were compared with those without a meniscal injury. The cartilage morphology was classified using a 6-grade scale [from 0 = normal thickness and signal, to 6 = diffuse full-thickness loss (>75 % of the region)]. The changes in cartilage status were evaluated at 14 sites. Cartilage changes were observed in all sites and were classified according to the site and degree of change. The majority of changes were grade 0 and 1, which accounted for 68 and 16.8 % of changes, respectively. The patella medial facet and anterolateral and centromedial femoral regions showed significantly more cartilage loss than the posteromedial, centrolateral, anterolateral, and anteromedial tibial regions. No significance was observed between the knees with or without combined injuries (n.s.). On the other hand, knees with or without combined injuries showed a different pattern of cartilage change, as demonstrated by different levels of grade change at sites. The change in cartilage status was minimal after a double-bundle ACL reconstruction. The patella medial facet, lateral femur anterior region, and medial femur central region showed significantly more cartilage loss than the medial tibia posterior, lateral tibia central, lateral tibia anterior, and medial tibia anterior regions. The presence of a combined injury did not affect the cartilage status changes, even though it was underpowered and too short term to assess the influence of the meniscal injury. Case series, Level IV.

Improved Conjugate Gradient Bundle Adjustment of Dunhuang Wall Painting Images

NASA Astrophysics Data System (ADS)

Hu, K.; Huang, X.; You, H.

2017-09-01

Bundle adjustment with additional parameters is identified as a critical step for precise orthoimage generation and 3D reconstruction of Dunhuang wall paintings. Due to the introduction of self-calibration parameters and quasi-planar constraints, the structure of coefficient matrix of the reduced normal equation is banded-bordered, making the solving process of bundle adjustment complex. In this paper, Conjugate Gradient Bundle Adjustment (CGBA) method is deduced by calculus of variations. A preconditioning method based on improved incomplete Cholesky factorization is adopt to reduce the condition number of coefficient matrix, as well as to accelerate the iteration rate of CGBA. Both theoretical analysis and experimental results comparison with conventional method indicate that, the proposed method can effectively conquer the ill-conditioned problem of normal equation and improve the calculation efficiency of bundle adjustment with additional parameters considerably, while maintaining the actual accuracy.

Coulomb explosion: a novel approach to separate single-walled carbon nanotubes from their bundle.

PubMed

Liu, Guangtong; Zhao, Yuanchun; Zheng, Kaihong; Liu, Zheng; Ma, Wenjun; Ren, Yan; Xie, Sishen; Sun, Lianfeng

2009-01-01

A novel approach based on Coulomb explosion has been developed to separate single-walled carbon nanotubes (SWNTs) from their bundle. With this technique, we can readily separate a bundle of SWNTs into smaller bundles with uniform diameter as well as some individual SWNTs. The separated SWNTs have a typical length of several microns and form a nanotree at one end of the original bundle. More importantly, this separating procedure involves no surfactant and includes only one-step physical process. The separation method offers great conveniences for the subsequent individual SWNT or multiterminal SWNTs device fabrication and their physical properties studies.

All-Inside Single-Bundle Reconstruction of the Anterior Cruciate Ligament with the Anterior Half of the Peroneus Longus Tendon Compared to the Semitendinosus Tendon: A Two-Year Follow-Up Study.

PubMed

Bi, Mingguang; Zhao, Chen; Zhang, Shuijun; Yao, Bin; Hong, Zheping; Bi, Qing

2018-02-08

The anterior half of the peroneus longus tendon (AHPLT) has been reported to be acceptable for ligament reconstruction with respect to strength and safety. However, there is little information regarding the clinical outcomes after using the AHPLT compared with other autograft tendons. A prospective randomized controlled study was performed to compare the results of 62 cases of all-inside anatomical single-bundle anterior cruciate ligament (ACL) reconstruction using the AHPLT and 62 cases using semitendinosus graft with an average of 30.0 ± 3.6 months' follow-up. Tunnel placements of enrolled cases were measured on three-dimensional (3D) computed tomography (CT) and X-ray imaging. Knee stability was assessed using the anterior drawer test, pivot shift test, and KT-1000. The International Knee Documentation Committee (IKDC) 2000 subjective score was used to evaluate functional outcomes. The American Orthopedic Foot and Ankle Score (AOFAS) and the assessment of eversion muscle strength were performed to evaluate the function of the ankle donor site. Tunnel positions, which were confirmed with 3D CT, were in the anatomical positions. At the final follow-up, there were no significant differences between the semitendinosus group and the AHPLT group in the IKDC score (90.4 ± 7.1 vs. 89.3. ± 8.4), KT 1000 measurements (1.71 ± 0.57 vs. 1.85 ± 0.77), pivot shift test, and Visual Analogue Scale (VAS) (0.15 ± 0.36 vs. 0.10 ± 0.30). No obvious ankle site complications were found at 24 months. The average AOFAS score of the AHPLT group was comparable to that of the semitendinosus tendon group (99.1 ± 1.40 vs. 99.5 ± 1.21). There was no significant difference in clinical outcomes or knee stability between the semitendinosus group and the AHPLT group at the 2-year follow-up. An AHPLT autograft may be a good alternative for all-inside ACL reconstruction with respect to its strength, safety, and donor site morbidity. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Articulated Bone Block for Posterior Cruciate Ligament Reconstruction Using Bone-Patellar Tendon-Bone Autograft: Surgical Technique to Facilitate Graft Passage.

PubMed

Cugat, Ramón; Alentorn-Geli, Eduard; Cuscó, Xavier; Navarro, Jordi; Steinbacher, Gilbert; Álvarez-Díaz, Pedro; Seijas, Roberto; Barastegui, David; García-Balletbó, Montse

2018-02-01

Posterior cruciate ligament reconstruction using the transtibial technique provides successful clinical outcomes. However, a bone-patellar tendon-bone (BTB) autograft with the transtibial technique has not been used by some surgeons because of concerns with graft passage from the tibial to the femoral tunnels (sharp turn) that can damage graft fibers. In the present surgical technique, an arthroscopic, transtibial, single-bundle technique for posterior cruciate ligament reconstruction using the BTB autograft with an easy and effective technical tip to facilitate graft passage is presented. Once the BTB is harvested, the femoral bone block is divided into 2 equal-sized blocks providing an articulated structure while preserving the tendon component. This facilitates the passage of the BTB tendon once it is entered in the posterior tibia and the graft has to make a sharp turn to reach the femoral tunnel. This easy and effective technique tip may avoid graft damage during the sharp turn, while maintaining all the advantages of a BTB autograft (bone-to-bone healing, own tissue with fast incorporation, and strong fixation and stability).

Hyperedge bundling: A practical solution to spurious interactions in MEG/EEG source connectivity analyses.

PubMed

Wang, Sheng H; Lobier, Muriel; Siebenhühner, Felix; Puoliväli, Tuomas; Palva, Satu; Palva, J Matias

2018-06-01

Inter-areal functional connectivity (FC), neuronal synchronization in particular, is thought to constitute a key systems-level mechanism for coordination of neuronal processing and communication between brain regions. Evidence to support this hypothesis has been gained largely using invasive electrophysiological approaches. In humans, neuronal activity can be non-invasively recorded only with magneto- and electroencephalography (MEG/EEG), which have been used to assess FC networks with high temporal resolution and whole-scalp coverage. However, even in source-reconstructed MEG/EEG data, signal mixing, or "source leakage", is a significant confounder for FC analyses and network localization. Signal mixing leads to two distinct kinds of false-positive observations: artificial interactions (AI) caused directly by mixing and spurious interactions (SI) arising indirectly from the spread of signals from true interacting sources to nearby false loci. To date, several interaction metrics have been developed to solve the AI problem, but the SI problem has remained largely intractable in MEG/EEG all-to-all source connectivity studies. Here, we advance a novel approach for correcting SIs in FC analyses using source-reconstructed MEG/EEG data. Our approach is to bundle observed FC connections into hyperedges by their adjacency in signal mixing. Using realistic simulations, we show here that bundling yields hyperedges with good separability of true positives and little loss in the true positive rate. Hyperedge bundling thus significantly decreases graph noise by minimizing the false-positive to true-positive ratio. Finally, we demonstrate the advantage of edge bundling in the visualization of large-scale cortical networks with real MEG data. We propose that hypergraphs yielded by bundling represent well the set of true cortical interactions that are detectable and dissociable in MEG/EEG connectivity analysis. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

The use of a computerized algorithm to determine single cardiac cell volumes.

PubMed

Marino, T A; Cook, L; Cook, P N; Dwyer, S J

1981-04-01

Single cardiac muscles cell volume data have been difficult to obtain, especially because the shape of a cell is quite complex. With the aid of a surface reconstruction method, a cell volume estimation algorithm has been developed that can be used on serial of cells. The cell surface is reconstructed by means of triangular tiles so that the cell is represented as a polyhedron. When this algorithm was tested on computer generated surfaces of a known volume, the difference was less than 1.6%. Serial sections of two phantoms of a known volume were also reconstructed and a comparison of the mathematically derived volumes and the computed volume estimations gave a per cent difference of between 2.8% and 4.1%. Finally cell volumes derived using conventional methods and volumes calculated using the algorithm were compared. The mean atrial muscle cell volume derived using conventional methods was 7752.7 +/- 644.7 micrometers3, while the mean computerized algorithm estimated atrial muscle cell volume was 7110.6 +/- 625.5 micrometers3. For AV bundle cells the mean cell volume obtained by conventional methods was 484.4 +/- 88.8 micrometers3 and the volume derived from the computer algorithm was 506.0 +/- 78.5 micrometers3. The differences between the volumes calculated using conventional methods and the algorithm were not significantly different.

Visualization of postoperative anterior cruciate ligament reconstruction bone tunnels

PubMed Central

2011-01-01

Background and purpose Non-anatomic bone tunnel placement is the most common cause of a failed ACL reconstruction. Accurate and reproducible methods to visualize and document bone tunnel placement are therefore important. We evaluated the reliability of standard radiographs, CT scans, and a 3-dimensional (3D) virtual reality (VR) approach in visualizing and measuring ACL reconstruction bone tunnel placement. Methods 50 consecutive patients who underwent single-bundle ACL reconstructions were evaluated postoperatively by standard radiographs, CT scans, and 3D VR images. Tibial and femoral tunnel positions were measured by 2 observers using the traditional methods of Amis, Aglietti, Hoser, Stäubli, and the method of Benereau for the VR approach. Results The tunnel was visualized in 50–82% of the standard radiographs and in 100% of the CT scans and 3D VR images. Using the intraclass correlation coefficient (ICC), the inter- and intraobserver agreement was between 0.39 and 0.83 for the standard femoral and tibial radiographs. CT scans showed an ICC range of 0.49–0.76 for the inter- and intraobserver agreement. The agreement in 3D VR was almost perfect, with an ICC of 0.83 for the femur and 0.95 for the tibia. Interpretation CT scans and 3D VR images are more reliable in assessing postoperative bone tunnel placement following ACL reconstruction than standard radiographs. PMID:21999625

From single muscle fiber to whole muscle mechanics: a finite element model of a muscle bundle with fast and slow fibers.

PubMed

Marcucci, Lorenzo; Reggiani, Carlo; Natali, Arturo N; Pavan, Piero G

2017-12-01

Muscles exhibit highly complex, multi-scale architecture with thousands of muscle fibers, each with different properties, interacting with each other and surrounding connective structures. Consequently, the results of single-fiber experiments are scarcely linked to the macroscopic or whole muscle behavior. This is especially true for human muscles where it would be important to understand of how skeletal muscles disorders affect patients' life. In this work, we developed a mathematical model to study how fast and slow muscle fibers, well characterized in single-fiber experiments, work and generate together force and displacement in muscle bundles. We characterized the parameters of a Hill-type model, using experimental data on fast and slow single human muscle fibers, and comparing experimental data with numerical simulations obtained from finite element (FE) models of single fibers. Then, we developed a FE model of a bundle of 19 fibers, based on an immunohistochemically stained cross section of human diaphragm and including the corresponding properties of each slow or fast fiber. Simulations of isotonic contractions of the bundle model allowed the generation of its apparent force-velocity relationship. Although close to the average of the force-velocity curves of fast and slow fibers, the bundle curve deviates substantially toward the fast fibers at low loads. We believe that the present model and the characterization of the force-velocity curve of a fiber bundle represents the starting point to link the single-fiber properties to those of whole muscle with FE application in phenomenological models of human muscles.

A probabilistic atlas of human brainstem pathways based on connectome imaging data.

PubMed

Tang, Yuchun; Sun, Wei; Toga, Arthur W; Ringman, John M; Shi, Yonggang

2018-04-01

The brainstem is a critical structure that regulates vital autonomic functions, houses the cranial nerves and their nuclei, relays motor and sensory information between the brain and spinal cord, and modulates cognition, mood, and emotions. As a primary relay center, the fiber pathways of the brainstem include efferent and afferent connections among the cerebral cortex, spinal cord, and cerebellum. While diffusion MRI has been successfully applied to map various brain pathways, its application for the in vivo imaging of the brainstem pathways has been limited due to inadequate resolution and large susceptibility-induced distortion artifacts. With the release of high-resolution data from the Human Connectome Project (HCP), there is increasing interest in mapping human brainstem pathways. Previous works relying on HCP data to study brainstem pathways, however, did not consider the prevalence (>80%) of large distortions in the brainstem even after the application of correction procedures from the HCP-Pipeline. They were also limited in the lack of adequate consideration of subject variability in either fiber pathways or region of interests (ROIs) used for bundle reconstruction. To overcome these limitations, we develop in this work a probabilistic atlas of 23 major brainstem bundles using high-quality HCP data passing rigorous quality control. For the large-scale data from the 500-Subject release of HCP, we conducted extensive quality controls to exclude subjects with severe distortions in the brainstem area. After that, we developed a systematic protocol to manually delineate 1300 ROIs on 20 HCP subjects (10 males; 10 females) for the reconstruction of fiber bundles using tractography techniques. Finally, we leveraged our novel connectome modeling techniques including high order fiber orientation distribution (FOD) reconstruction from multi-shell diffusion imaging and topography-preserving tract filtering algorithms to successfully reconstruct the 23 fiber bundles for each subject, which were then used to calculate the probabilistic atlases in the MNI152 space for public release. In our experimental results, we demonstrate that our method yielded anatomically faithful reconstruction of the brainstem pathways and achieved improved performance in comparison with an existing atlas of cerebellar peduncles based on HCP data. These atlases have been publicly released on NITRIC (https://www.nitrc.org/projects/brainstem_atlas/) and can be readily used by brain imaging researchers interested in studying brainstem pathways. Copyright © 2017 Elsevier Inc. All rights reserved.

Lineage-associated tracts defining the anatomy of the Drosophila first instar larval brain

PubMed Central

Hartenstein, Volker; Younossi-Hartenstein, Amelia; Lovick, Jennifer; Kong, Angel; Omoto, Jaison; Ngo, Kathy; Viktorin, Gudrun

2015-01-01

Fixed lineages derived from unique, genetically specified neuroblasts form the anatomical building blocks of the Drosophila brain. Neurons belonging to the same lineage project their axons in a common tract, which is labeled by neuronal markers. In this paper, we present a detailed atlas of the lineage-associated tracts forming the brain of the early Drosophila larva, based on the use of global markers (anti-Neuroglian, anti-Neurotactin, Inscuteable-Gal4>UAS-chRFP-Tub) and lineage-specific reporters. We describe 68 discrete fiber bundles that contain axons of one lineage or pairs/small sets of adjacent lineages. Bundles enter the neuropil at invariant locations, the lineage tract entry portals. Within the neuropil, these fiber bundles form larger fascicles that can be classified, by their main orientation, into longitudinal, transverse, and vertical (ascending/descending) fascicles. We present 3D digital models of lineage tract entry portals and neuropil fascicles, set into relationship to commonly used, easily recognizable reference structures such as the mushroom body, the antennal lobe, the optic lobe, and the Fasciclin II-positive fiber bundles that connect the brain and ventral nerve cord. Correspondences and differences between early larval tract anatomy and the previously described late larval and adult lineage patterns are highlighted. Our L1 neuro-anatomical atlas of lineages constitutes an essential step towards following morphologically defined lineages to the neuroblasts of the early embryo, which will ultimately make it possible to link the structure and connectivity of a lineage to the expression of genes in the particular neuroblast that gives rise to that lineage. Furthermore, the L1 atlas will be important for a host of ongoing work that attempts to reconstruct neuronal connectivity at the level of resolution of single neurons and their synapses. PMID:26141956

Lineage-associated tracts defining the anatomy of the Drosophila first instar larval brain.

PubMed

Hartenstein, Volker; Younossi-Hartenstein, Amelia; Lovick, Jennifer K; Kong, Angel; Omoto, Jaison J; Ngo, Kathy T; Viktorin, Gudrun

2015-10-01

Fixed lineages derived from unique, genetically specified neuroblasts form the anatomical building blocks of the Drosophila brain. Neurons belonging to the same lineage project their axons in a common tract, which is labeled by neuronal markers. In this paper, we present a detailed atlas of the lineage-associated tracts forming the brain of the early Drosophila larva, based on the use of global markers (anti-Neuroglian, anti-Neurotactin, inscuteable-Gal4>UAS-chRFP-Tub) and lineage-specific reporters. We describe 68 discrete fiber bundles that contain axons of one lineage or pairs/small sets of adjacent lineages. Bundles enter the neuropil at invariant locations, the lineage tract entry portals. Within the neuropil, these fiber bundles form larger fascicles that can be classified, by their main orientation, into longitudinal, transverse, and vertical (ascending/descending) fascicles. We present 3D digital models of lineage tract entry portals and neuropil fascicles, set into relationship to commonly used, easily recognizable reference structures such as the mushroom body, the antennal lobe, the optic lobe, and the Fasciclin II-positive fiber bundles that connect the brain and ventral nerve cord. Correspondences and differences between early larval tract anatomy and the previously described late larval and adult lineage patterns are highlighted. Our L1 neuro-anatomical atlas of lineages constitutes an essential step towards following morphologically defined lineages to the neuroblasts of the early embryo, which will ultimately make it possible to link the structure and connectivity of a lineage to the expression of genes in the particular neuroblast that gives rise to that lineage. Furthermore, the L1 atlas will be important for a host of ongoing work that attempts to reconstruct neuronal connectivity at the level of resolution of single neurons and their synapses. Copyright © 2015 Elsevier Inc. All rights reserved.

Rehabilitating the Wounded: Historical Perspective on Army Policy

DTIC Science & Technology

2008-06-01

rehabilitation. However, “reconstruction aides” (civilian employees, now Occupational and Physical Therapists ) provided care that speeded healing...Rehabilitation Act.35) However, when occupational therapists (then bundled with physical therapists under the term “reconstruction aides”) were assigned to...functional restoration,” which meant accepting the female occupational and physical therapists onto the fringes of an all-male Army.38 With

Anterior cruciate ligament reconstruction and cartilage contact forces--A 3D computational simulation.

PubMed

Wang, Lianxin; Lin, Lin; Feng, Yong; Fernandes, Tiago Lazzaretti; Asnis, Peter; Hosseini, Ali; Li, Guoan

2015-12-01

Clinical outcome studies showed a high incidence of knee osteoarthritis after anterior cruciate ligament reconstruction. Abnormal joint kinematics and loading conditions were assumed as risking factors. However, little is known on cartilage contact forces after the surgery. A validated computational model was used to simulate anatomic and transtibial single-bundle anterior cruciate ligament reconstructions. Two graft fixation angles (0° and 30°) were simulated for each reconstruction. Biomechanics of the knee was investigated in intact, anterior cruciate ligament deficient and reconstructed conditions when the knee was subjected to 134 N anterior load and 400 N quadriceps load at 0°, 30°, 60° and 90° of flexion. The tibial translation and rotation, graft forces, medial and lateral contact forces were calculated. When the graft was fixed at 0°, the anatomic reconstruction resulted in slightly larger lateral contact force at 0° compared to the intact knee while the transtibial technique led to higher contact force at both 0° and 30° under the muscle load. When graft was fixed at 30°, the anatomic reconstruction overstrained the knee at 0° with larger contact forces, while the transtibial technique resulted in slightly larger contact forces at 30°. This study suggests that neither the anatomic nor the transtibial reconstruction can consistently restore normal knee biomechanics at different flexion angles. The anatomic reconstruction may better restore anteroposterior stability and contact force with the graft fixed at 0°. The transtibial technique may better restore knee anteroposterior stability and articular contact force with the graft fixed at 30° of flexion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Impingement following anterior cruciate ligament reconstruction: comparing the direct versus indirect femoral tunnel position.

PubMed

van der List, J P; Zuiderbaan, H A; Nawabi, D H; Pearle, A D

2017-05-01

During anterior cruciate ligament (ACL) reconstruction, authors have suggested inserting the femoral tunnel at the biomechanically relevant direct fibres, but this higher position can cause more impingement. Therefore, we aimed to assess ACL graft impingement at the femoral notch for ACL reconstruction at both the direct and indirect tunnel positions. A virtual model was created for twelve cadaveric knees with computed tomography scanning in which a virtual graft was placed at direct and indirect tunnel positions of the anteromedial bundle (AM), posterolateral bundle (PL) or centre of the both bundles (C). In these six tunnel positions, the volume (mm 3 ) and mid-point location of impingement (°) were measured at different flexion angles. Generally, more impingement was seen with the indirect position compared with the direct position although this was only significant at 90° of flexion for the AM position (97 ± 28 vs. 76 ± 20 mm 3 , respectively; p = 0.046). The direct tunnel position impinged higher at the notch, whereas the indirect position impinged more towards the lateral wall, but this was only significant at 90° of flexion for the AM (24 ± 5° vs. 34 ± 4°, respectively; p < 0.001) and C position (34 ± 5° vs. 42 ± 5°, respectively; p = 0.003). In this cadaveric study, the direct tunnel position did not cause more impingement than the indirect tunnel position. Based on these results, graft impingement is not a limitation to reconstruct the femoral tunnel at the insertion of the biomechanically more relevant direct fibres.

Coronal in vivo forward-imaging of rat brain morphology with an ultra-small optical coherence tomography fiber probe

NASA Astrophysics Data System (ADS)

Xie, Yijing; Bonin, Tim; Löffler, Susanne; Hüttmann, Gereon; Tronnier, Volker; Hofmann, Ulrich G.

2013-02-01

A well-established navigation method is one of the key conditions for successful brain surgery: it should be accurate, safe and online operable. Recent research shows that optical coherence tomography (OCT) is a potential solution for this application by providing a high resolution and small probe dimension. In this study a fiber-based spectral-domain OCT system utilizing a super-luminescent-diode with the center wavelength of 840 nm providing 14.5 μm axial resolution was used. A composite 125 μm diameter detecting probe with a gradient index (GRIN) fiber fused to a single mode fiber was employed. Signals were reconstructed into grayscale images by horizontally aligning A-scans from the same trajectory with different depths. The reconstructed images can display brain morphology along the entire trajectory. For scans of typical white matter, the signals showed a higher reflection of light intensity with lower penetration depth as well as a steeper attenuation rate compared to the scans typical for gray matter. Micro-structures such as axon bundles (70 μm) in the caudate nucleus are visible in the reconstructed images. This study explores the potential of OCT to be a navigation modality in brain surgery.

Structure and Characterization of Vertically Aligned Single-Walled Carbon Nanotube Bundles

DOE PAGES

Márquez, Francisco; López, Vicente; Morant, Carmen; ...

2010-01-01

Arrmore » ays of vertically aligned single-walled carbon nanotube bundles, SWCNTs, have been synthesized by simple alcohol catalytic chemical vapor deposition process, carried out at 800 ° C . The formed SWCNTs are organized in small groups perpendicularly aligned and attached to the substrate. These small bundles show a constant diameter of ca. 30 nm and are formed by the adhesion of no more than twenty individual SWCNTs perfectly aligned along their length.« less

Economic Analyses in Anterior Cruciate Ligament Reconstruction: A Qualitative and Systematic Review.

PubMed

Saltzman, Bryan M; Cvetanovich, Gregory L; Nwachukwu, Benedict U; Mall, Nathan A; Bush-Joseph, Charles A; Bach, Bernard R

2016-05-01

As the health care system in the United States (US) transitions toward value-based care, there is an increased emphasis on understanding the cost drivers and high-value procedures within orthopaedics. To date, there has been no systematic review of the economic literature on anterior cruciate ligament reconstruction (ACLR). To evaluate the overall evidence base for economic studies published on ACLR in the orthopaedic literature. Data available on the economics of ACLR are summarized and cost drivers associated with the procedure are identified. Systematic review. All economic studies (including US-based and non-US-based) published between inception of the MEDLINE database and October 3, 2014, were identified. Given the heterogeneity of the existing evidence base, a qualitative, descriptive approach was used to assess the collective results from the economic studies on ACLR. When applicable, comparisons were made for the following cost-related variables associated with the procedure for economic implications: outpatient versus inpatient surgery (or outpatient vs overnight hospital stay vs >1-night stay); bone-patellar tendon-bone (BPTB) graft versus hamstring (HS) graft source; autograft versus allograft source; staged unilateral ACLR versus bilateral ACLR in a single setting; single- versus double-bundle technique; ACLR versus nonoperative treatment; and other unique comparisons reported in single studies, including computer-assisted navigation surgery (CANS) versus traditional surgery, early versus delayed ACLR, single- versus double-incision technique, and finally the costs of ACLR without comparison of variables. A total of 24 studies were identified and included; of these, 17 included studies were cost identification studies. The remaining 7 studies were cost utility analyses that used economic models to investigate the effect of variables such as the cost of allograft tissue, fixation devices, and physical therapy, the percentage and timing of revision surgery, and the cost of revision surgery. Of the 24 studies, there were 3 studies with level 1 evidence, 8 with level 2 evidence, 6 with level 3 evidence, and 7 with level 4 evidence. The following economic comparisons were demonstrated: (1) ACLR is more cost-effective than nonoperative treatment with rehabilitation only (per 3 cost utility analyses); (2) autograft use had lower total costs than allograft use, with operating room supply costs and allograft costs most significant (per 5 cost identification studies and 1 cost utility analysis); (3) results on hamstring versus BPTB graft source are conflicting (per 2 cost identification studies); (4) there is significant cost reduction with an outpatient versus inpatient setting (per 5 studies using cost identification analyses); (5) bilateral ACLR is more cost efficient than 2 unilateral ACLRs in separate settings (per 2 cost identification studies); (6) there are lower costs with similarly successful outcomes between single- and double-bundle technique (per 3 cost identification studies and 2 cost utility analyses). Results from this review suggest that early single-bundle, single (endoscopic)-incision outpatient ACLR using either BPTB or HS autograft provides the most value. In the setting of bilateral ACL rupture, single-setting bilateral ACLR is more cost-effective than staged unilateral ACLR. Procedures using CANS technology do not yet yield results that are superior to the results of a standard surgical procedure, and CANS has substantially greater costs. © 2015 The Author(s).

Thomson scattering diagnostic on the Compact Toroidal Hybrid Experiment

NASA Astrophysics Data System (ADS)

Traverso, P. J.; Ennis, D. A.; Hartwell, G. J.; Kring, J. D.; Maurer, D. A.

2017-10-01

A Thomson scattering system is being commissioned for the non-axisymmetric plasmas of the Compact Toroidal Hybrid (CTH), a five-field period current-carrying torsatron. The system takes a single point measurement at the magnetic axis to both calibrate the two-color soft x-ray Te system and serve as an additional diagnostic for the V3FIT 3D equilibrium reconstruction code. A single point measurement will reduce the uncertainty in the reconstructed peak pressure by an order of magnitude for both current-carrying plasmas and future gyrotron-heated stellarator plasmas. The beam, generated by a frequency doubled Continuum 2 J, Nd:YAG laser, is passed vertically through an entrance Brewster window and a two-aperture optical baffle system to minimize stray light. Thomson scattered light is collected by two adjacent f/2 plano-convex condenser lenses and routed via a fiber bundle through a Holospec f/1.8 spectrograph. The red-shifted scattered light from 533-563 nm will be collected by an array of Hamamatsu H11706-40 PMTs. The system has been designed to measure plasmas with core Te of 100 to 200 eV and densities of 5 ×1018 to 5 ×1019 m-3. Stray light and calibration data for a single wavelength channel will be presented. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.

Failure Rate and Clinical Outcomes of Anterior Cruciate Ligament Reconstruction Using Autograft Hamstring Versus a Hybrid Graft.

PubMed

Leo, Brian M; Krill, Michael; Barksdale, Leticia; Alvarez-Pinzon, Andres M

2016-11-01

To compare the revision rate and subjective outcome measures of autograft hamstring versus a soft tissue hybrid graft combining both autograft hamstring and tibialis allograft for isolated anterior cruciate ligament (ACL) reconstruction. A single-center retrospective, nonrandomized, comparative study of isolated ACL reconstruction revision rates for subjects who underwent arthroscopic reconstruction of the ACL using autograft hamstring or a soft tissue hybrid graft using both autograft hamstring and tibialis allograft was performed. Patients with isolated ACL tears were included and underwent anatomic single-bundle reconstruction using an independent tunnel drilling technique and a minimum of 24 months' follow-up. The primary outcome assessed was the presence or absence of ACL rerupture. Secondary clinical outcomes consisted of the International Knee Documentation Committee, University of California at Los Angeles (UCLA) ACL quality of life assessment, and the visual analog pain scale. Between February 2010 and April 2013, 95 patients with isolated ACL tears between ages 18 and 40 met the inclusion criteria and were enrolled. Seventy-one autograft hamstring and 24 soft tissue hybrid graft ACL reconstructions were performed during the course of this study. The follow-up period was 24 to 32 months (mean 26.9 months). There were no statistically significant differences in patient demographics or Outerbridge classification. No statistically significant differences in ACL retears (5.6% auto, 4.2% hybrid; P = .57) were found between groups. Clinical International Knee Documentation Committee and UCLA ACL quality of life assessment improvement scores revealed no statistically significant differences in autograft and hybrid graft reconstructions (41 ± 11, 43 ± 13; P = .65) (38 ± 11, 40 ± 10; P = .23). The mean pain level decreased from 8.1 to 2.8 in the autograft group and 7.9 to 2.5 in the hybrid group (P = .18). The use of a hybrid soft tissue graft has a comparable rerupture rate and clinical outcome to ACL reconstruction using autograft hamstring. Level III, retrospective comparative study. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Non-Relativistic Twistor Theory and Newton-Cartan Geometry

NASA Astrophysics Data System (ADS)

Dunajski, Maciej; Gundry, James

2016-03-01

We develop a non-relativistic twistor theory, in which Newton-Cartan structures of Newtonian gravity correspond to complex three-manifolds with a four-parameter family of rational curves with normal bundle O oplus O(2)}. We show that the Newton-Cartan space-times are unstable under the general Kodaira deformation of the twistor complex structure. The Newton-Cartan connections can nevertheless be reconstructed from Merkulov's generalisation of the Kodaira map augmented by a choice of a holomorphic line bundle over the twistor space trivial on twistor lines. The Coriolis force may be incorporated by holomorphic vector bundles, which in general are non-trivial on twistor lines. The resulting geometries agree with non-relativistic limits of anti-self-dual gravitational instantons.

Determining physiological cross-sectional area of extensor carpi radialis longus and brevis as a whole and by regions using 3D computer muscle models created from digitized fiber bundle data.

PubMed

Ravichandiran, Kajeandra; Ravichandiran, Mayoorendra; Oliver, Michele L; Singh, Karan S; McKee, Nancy H; Agur, Anne M R

2009-09-01

Architectural parameters and physiological cross-sectional area (PCSA) are important determinants of muscle function. Extensor carpi radialis longus (ECRL) and brevis (ECRB) are used in muscle transfers; however, their regional architectural differences have not been investigated. The aim of this study is to develop computational algorithms to quantify and compare architectural parameters (fiber bundle length, pennation angle, and volume) and PCSA of ECRL and ECRB. Fiber bundles distributed throughout the volume of ECRL (75+/-20) and ECRB (110+/-30) were digitized in eight formalin embalmed cadaveric specimens. The digitized data was reconstructed in Autodesk Maya with computational algorithms implemented in Python. The mean PCSA and fiber bundle length were significantly different between ECRL and ECRB (p < or = 0.05). Superficial ECRL had significantly longer fiber bundle length than the deep region, whereas the PCSA of superficial ECRB was significantly larger than the deep region. The regional quantification of architectural parameters and PCSA provides a framework for the exploration of partial tendon transfers of ECRL and ECRB.

Microoptical compound lens

DOEpatents

Sweatt, William C.; Gill, David D.

2007-10-23

An apposition microoptical compound lens comprises a plurality of lenslets arrayed around a segment of a hollow, three-dimensional optical shell. The lenslets collect light from an object and focus the light rays onto the concentric, curved front surface of a coherent fiber bundle. The fiber bundle transports the light rays to a planar detector, forming a plurality of sub-images that can be reconstructed as a full image. The microoptical compound lens can have a small size (millimeters), wide field of view (up to 180.degree.), and adequate resolution for object recognition and tracking.

Field emission properties of a DWCNT bundle and a single MWCNT

NASA Astrophysics Data System (ADS)

Fujishige, Masatsugu; Wongwiriyapan, Winadda; Muramatsu, Hiroyuki; Takeuchi, Kenji; Arai, Susumu

2018-02-01

The field emission properties of a bundle of double-walled carbon nanotubes (DWCNTs) and a single multiwalled carbon nanotube (MWCNT) were investigated. A DWCNT bundle or a single MWCNT was attached to the head of sharpened tip of tungsten by electrophoresis; the tungsten tip was dipped into a drop of a carbon nanotube/1,2-dichloroethane suspension on a stainless plate, and a high-frequency AC voltage (20 V peak to peak with a frequency of 15 MHz) was applied between the tungsten tip and the stainless steel plate. The turn-on fields of the DWCNT and MWCNT tips for 1 nA/cm2 were 0.05 and 0.48 V/μm, respectively. From the Fowler-Nordheim plots, the field enhancement factor (β) of the tips was estimated to be 109,600 (DWCNT) and 6780 (MWCNT). The present DWCNT emitter is characterized by a very small turn-on field and large β. The field emission performance is discussed in terms of the sizes of the bundle of DWCNTs and a single MWCNT.

Ab initio density functional theory investigation of electronic properties of semiconducting single-walled carbon nanotube bundles

NASA Astrophysics Data System (ADS)

Moradian, Rostam; Behzad, Somayeh; Azadi, Sam

2008-09-01

By using ab initio density functional theory we investigated the structural and electronic properties of semiconducting (7, 0), (8, 0) and (10, 0) carbon nanotube bundles. The energetic and electronic evolutions of nanotubes in the bundling process are also studied. The effects of inter-tube coupling on the electronic dispersions of semiconducting carbon nanotube bundles are demonstrated. Our results show that the inter-tube coupling decreases the energy gap in semiconducting nanotubes. We found that bundles of (7, 0) and (8, 0) carbon nanotubes have metallic feature, while (10, 0) bundle is a semiconductor with an energy gap of 0.22 eV. To clarify our results the band structures of isolated and bundled nanotubes are compared.

Calculation of Non-Bonded Forces Due to Sliding of Bundled Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Frankland, S. J. V.; Bandorawalla, T.; Gates, T. S.

2003-01-01

An important consideration for load transfer in bundles of single-walled carbon nanotubes is the nonbonded (van der Waals) forces between the nanotubes and their effect on axial sliding of the nanotubes relative to each other. In this research, the non-bonded forces in a bundle of seven hexagonally packed (10,10) single-walled carbon nanotubes are represented as an axial force applied to the central nanotube. A simple model, based on momentum balance, is developed to describe the velocity response of the central nanotube to the applied force. The model is verified by comparing its velocity predictions with molecular dynamics simulations that were performed on the bundle with different force histories applied to the central nanotube. The model was found to quantitatively predict the nanotube velocities obtained from the molecular dynamics simulations. Both the model and the simulations predict a threshold force at which the nanotube releases from the bundle. This force converts to a shear yield strength of 10.5-11.0 MPa for (10,10) nanotubes in a bundle.

Characterization of active hair-bundle motility by a mechanical-load clamp

NASA Astrophysics Data System (ADS)

Salvi, Joshua D.; Maoiléidigh, Dáibhid Ó.; Fabella, Brian A.; Tobin, Mélanie; Hudspeth, A. J.

2015-12-01

Active hair-bundle motility endows hair cells with several traits that augment auditory stimuli. The activity of a hair bundle might be controlled by adjusting its mechanical properties. Indeed, the mechanical properties of bundles vary between different organisms and along the tonotopic axis of a single auditory organ. Motivated by these biological differences and a dynamical model of hair-bundle motility, we explore how adjusting the mass, drag, stiffness, and offset force applied to a bundle control its dynamics and response to external perturbations. Utilizing a mechanical-load clamp, we systematically mapped the two-dimensional state diagram of a hair bundle. The clamp system used a real-time processor to tightly control each of the virtual mechanical elements. Increasing the stiffness of a hair bundle advances its operating point from a spontaneously oscillating regime into a quiescent regime. As predicted by a dynamical model of hair-bundle mechanics, this boundary constitutes a Hopf bifurcation.

All-optical endoscopic probe for high resolution 3D photoacoustic tomography

NASA Astrophysics Data System (ADS)

Ansari, R.; Zhang, E.; Desjardins, A. E.; Beard, P. C.

2017-03-01

A novel all-optical forward-viewing photoacoustic probe using a flexible coherent fibre-optic bundle and a Fabry- Perot (FP) ultrasound sensor has been developed. The fibre bundle, along with the FP sensor at its distal end, synthesizes a high density 2D array of wideband ultrasound detectors. Photoacoustic waves arriving at the sensor are spatially mapped by optically scanning the proximal end face of the bundle in 2D with a CW wavelength-tunable interrogation laser. 3D images are formed from the detected signals using a time-reversal image reconstruction algorithm. The system has been characterized in terms of its PSF, noise-equivalent pressure and field of view. Finally, the high resolution 3D imaging capability has been demonstrated using arbitrary shaped phantoms and duck embryo.

Template-directed atomically precise self-organization of perfectly ordered parallel cerium silicide nanowire arrays on Si(110)-16 × 2 surfaces.

PubMed

Hong, Ie-Hong; Liao, Yung-Cheng; Tsai, Yung-Feng

2013-11-05

The perfectly ordered parallel arrays of periodic Ce silicide nanowires can self-organize with atomic precision on single-domain Si(110)-16 × 2 surfaces. The growth evolution of self-ordered parallel Ce silicide nanowire arrays is investigated over a broad range of Ce coverages on single-domain Si(110)-16 × 2 surfaces by scanning tunneling microscopy (STM). Three different types of well-ordered parallel arrays, consisting of uniformly spaced and atomically identical Ce silicide nanowires, are self-organized through the heteroepitaxial growth of Ce silicides on a long-range grating-like 16 × 2 reconstruction at the deposition of various Ce coverages. Each atomically precise Ce silicide nanowire consists of a bundle of chains and rows with different atomic structures. The atomic-resolution dual-polarity STM images reveal that the interchain coupling leads to the formation of the registry-aligned chain bundles within individual Ce silicide nanowire. The nanowire width and the interchain coupling can be adjusted systematically by varying the Ce coverage on a Si(110) surface. This natural template-directed self-organization of perfectly regular parallel nanowire arrays allows for the precise control of the feature size and positions within ±0.2 nm over a large area. Thus, it is a promising route to produce parallel nanowire arrays in a straightforward, low-cost, high-throughput process.

Template-directed atomically precise self-organization of perfectly ordered parallel cerium silicide nanowire arrays on Si(110)-16 × 2 surfaces

PubMed Central

2013-01-01

The perfectly ordered parallel arrays of periodic Ce silicide nanowires can self-organize with atomic precision on single-domain Si(110)-16 × 2 surfaces. The growth evolution of self-ordered parallel Ce silicide nanowire arrays is investigated over a broad range of Ce coverages on single-domain Si(110)-16 × 2 surfaces by scanning tunneling microscopy (STM). Three different types of well-ordered parallel arrays, consisting of uniformly spaced and atomically identical Ce silicide nanowires, are self-organized through the heteroepitaxial growth of Ce silicides on a long-range grating-like 16 × 2 reconstruction at the deposition of various Ce coverages. Each atomically precise Ce silicide nanowire consists of a bundle of chains and rows with different atomic structures. The atomic-resolution dual-polarity STM images reveal that the interchain coupling leads to the formation of the registry-aligned chain bundles within individual Ce silicide nanowire. The nanowire width and the interchain coupling can be adjusted systematically by varying the Ce coverage on a Si(110) surface. This natural template-directed self-organization of perfectly regular parallel nanowire arrays allows for the precise control of the feature size and positions within ±0.2 nm over a large area. Thus, it is a promising route to produce parallel nanowire arrays in a straightforward, low-cost, high-throughput process. PMID:24188092

Surgical retrieval, isolation and in vitro expansion of human anterior cruciate ligament-derived cells for tissue engineering applications.

PubMed

Gupta, Ashim; Sharif, Kevin; Walters, Megan; Woods, Mia D; Potty, Anish; Main, Benjamin J; El-Amin, Saadiq F

2014-04-30

Injury to the ACL is a commonly encountered problem in active individuals. Even partial tears of this intra-articular knee ligament lead to biomechanical deficiencies that impair function and stability. Current options for the treatment of partial ACL tears range from nonoperative, conservative management to multiple surgical options, such as: thermal modification, single-bundle repair, complete reconstruction, and reconstruction of the damaged portion of the native ligament. Few studies, if any, have demonstrated any single method for management to be consistently superior, and in many cases patients continue to demonstrate persistent instability and other comorbidities. The goal of this study is to identify a potential cell source for utilization in the development of a tissue engineered patch that could be implemented in the repair of a partially torn ACL. A novel protocol was developed for the expansion of cells derived from patients undergoing ACL reconstruction. To isolate the cells, minced hACL tissue obtained during ACL reconstruction was digested in a Collagenase solution. Expansion was performed using DMEM/F12 medium supplemented with 10% fetal bovine serum (FBS) and 1% penicillin/streptomycin (P/S). The cells were then stored at -80 ºC or in liquid nitrogen in a freezing medium consisting of DMSO, FBS and the expansion medium. After thawing, the hACL derived cells were then seeded onto a tissue engineered scaffold, PLAGA (Poly lactic-co-glycolic acid) and control Tissue culture polystyrene (TCPS). After 7 days, SEM was performed to compare cellular adhesion to the PLAGA versus the control TCPS. Cellular morphology was evaluated using immunofluorescence staining. SEM (Scanning Electron Microscope) micrographs demonstrated that cells grew and adhered on both PLAGA and TCPS surfaces and were confluent over the entire surfaces by day 7. Immunofluorescence staining showed normal, non-stressed morphological patterns on both surfaces. This technique is promising for applications in ACL regeneration and reconstruction.

Surgical Retrieval, Isolation and In vitro Expansion of Human Anterior Cruciate Ligament-derived Cells for Tissue Engineering Applications

PubMed Central

Gupta, Ashim; Sharif, Kevin; Walters, Megan; Woods, Mia D.; Potty, Anish; Main, Benjamin J.; El-Amin, Saadiq F.

2014-01-01

Injury to the ACL is a commonly encountered problem in active individuals. Even partial tears of this intra-articular knee ligament lead to biomechanical deficiencies that impair function and stability. Current options for the treatment of partial ACL tears range from nonoperative, conservative management to multiple surgical options, such as: thermal modification, single-bundle repair, complete reconstruction, and reconstruction of the damaged portion of the native ligament. Few studies, if any, have demonstrated any single method for management to be consistently superior, and in many cases patients continue to demonstrate persistent instability and other comorbidities. The goal of this study is to identify a potential cell source for utilization in the development of a tissue engineered patch that could be implemented in the repair of a partially torn ACL. A novel protocol was developed for the expansion of cells derived from patients undergoing ACL reconstruction. To isolate the cells, minced hACL tissue obtained during ACL reconstruction was digested in a Collagenase solution. Expansion was performed using DMEM/F12 medium supplemented with 10% fetal bovine serum (FBS) and 1% penicillin/streptomycin (P/S). The cells were then stored at -80 ºC or in liquid nitrogen in a freezing medium consisting of DMSO, FBS and the expansion medium. After thawing, the hACL derived cells were then seeded onto a tissue engineered scaffold, PLAGA (Poly lactic-co-glycolic acid) and control Tissue culture polystyrene (TCPS). After 7 days, SEM was performed to compare cellular adhesion to the PLAGA versus the control TCPS. Cellular morphology was evaluated using immunofluorescence staining. SEM (Scanning Electron Microscope) micrographs demonstrated that cells grew and adhered on both PLAGA and TCPS surfaces and were confluent over the entire surfaces by day 7. Immunofluorescence staining showed normal, non-stressed morphological patterns on both surfaces. This technique is promising for applications in ACL regeneration and reconstruction. PMID:24836540

Localized Statistics for DW-MRI Fiber Bundle Segmentation

PubMed Central

Lankton, Shawn; Melonakos, John; Malcolm, James; Dambreville, Samuel; Tannenbaum, Allen

2013-01-01

We describe a method for segmenting neural fiber bundles in diffusion-weighted magnetic resonance images (DWMRI). As these bundles traverse the brain to connect regions, their local orientation of diffusion changes drastically, hence a constant global model is inaccurate. We propose a method to compute localized statistics on orientation information and use it to drive a variational active contour segmentation that accurately models the non-homogeneous orientation information present along the bundle. Initialized from a single fiber path, the proposed method proceeds to capture the entire bundle. We demonstrate results using the technique to segment the cingulum bundle and describe several extensions making the technique applicable to a wide range of tissues. PMID:23652079

Lexical Bundle Analysis in Mathematics Classroom Discourse: The Significance of Stance

ERIC Educational Resources Information Center

Herbel-Eisenmann, Beth; Wagner, David; Cortes, Viviana

2010-01-01

In this article, we introduce the lexical bundle, defined by corpus linguists as a group of three or more words that frequently recur together, in a single group, in a particular register (Biber, Johansson, Leech, Conrad, & Finegan, 2006; Cortes, "English for Specific Purposes" 23:397-423, 2004). Attention to lexical bundles helps to explore…

The ultrastructure of mono- and holocentric plant centromeres: an immunological investigation by structured illumination microscopy and scanning electron microscopy.

PubMed

Wanner, Gerhard; Schroeder-Reiter, Elizabeth; Ma, Wei; Houben, Andreas; Schubert, Veit

2015-12-01

The spatial distribution of the three centromere-associated proteins α-tubulin, CENH3, and phosphorylated histone H2A (at threonine 120, H2AThr120ph) was analysed by indirect immunodetection at monocentric cereal chromosomes and at the holocentric chromosomes of Luzula elegans by super-resolution light microscopy and scanning electron microscopy (SEM). Using structured illumination microscopy (SIM) as the super-resolution technique on squashed specimens and SEM on uncoated isolated specimens, the three-dimensional (3D) distribution of the proteins was visualized at the centromeres. Technical aspects of 3D SEM are explained in detail. We show that CENH3 forms curved "pads" mainly around the lateral centromeric region in the primary constriction of metacentric chromosomes. H2AThr120ph is present in both the primary constriction and in the pericentromere. α-tubulin-labeled microtubule bundles attach to CENH3-containing chromatin structures, either in single bundles with a V-shaped attachment to the centromere or in split bundles to bordering pericentromeric flanks. In holocentric L. elegans chromosomes, H2AThr120ph is located predominantly in the centromeric groove of each chromatid as proven by subsequent FIB/FESEM ablation and 3D reconstruction. α-tubulin localizes to the edges of the groove. In both holocentric and monocentric chromosomes, no additional intermediate structures between microtubules and the centromere were observed. We established models of the distribution of CENH3, H2AThr120ph and the attachment sites of microtubules for metacentric and holocentric plant chromosomes.

Flat midsubstance of the anterior cruciate ligament with tibial "C"-shaped insertion site.

PubMed

Siebold, Rainer; Schuhmacher, Peter; Fernandez, Francis; Śmigielski, Robert; Fink, Christian; Brehmer, Axel; Kirsch, Joachim

2015-11-01

This anatomical cadaver study was performed to investigate the flat appearance of the midsubstance shape of the anterior cruciate ligament (ACL) and its tibial "C"-shaped insertion site. The ACL midsubstance and the tibial ACL insertion were dissected in 20 cadaveric knees (n = 6 fresh frozen and n = 14 paraffined). Magnifying spectacles were used for all dissections. Morphometric measurements were performed using callipers and on digital photographs. In all specimens, the midsubstance of the ACL was flat with a mean width of 9.9 mm, thickness of 3.9 mm and cross-sectional area of 38.7 mm(2). The "direct" "C"-shaped tibial insertion runs from along the medial tibial spine to the anterior aspect of the lateral meniscus. The mean width (length) of the "C" was 12.6 mm, its thickness 3.3 mm and area 31.4 mm(2). The centre of the "C" was the bony insertion of the anterior root of the lateral meniscus overlayed by fat and crossed by the ACL. No posterolateral (PL) inserting ACL fibres were found. Together with the larger "indirect" part (area 79.6 mm(2)), the "direct" one formed a "duck-foot"-shaped footprint. The tibial ACL midsubstance and tibial "C"-shaped insertion are flat and are resembling a "ribbon". The centre of the "C" is the bony insertion of the anterior root of the lateral meniscus. There are no central or PL inserting ACL fibres. Anatomical ACL reconstruction may therefore require a flat graft and a "C"-shaped tibial footprint reconstruction with an anteromedial bone tunnel for single bundle and an additional posteromedial bone tunnel for double bundle.

Kernel Regression Estimation of Fiber Orientation Mixtures in Diffusion MRI

PubMed Central

Cabeen, Ryan P.; Bastin, Mark E.; Laidlaw, David H.

2016-01-01

We present and evaluate a method for kernel regression estimation of fiber orientations and associated volume fractions for diffusion MR tractography and population-based atlas construction in clinical imaging studies of brain white matter. This is a model-based image processing technique in which representative fiber models are estimated from collections of component fiber models in model-valued image data. This extends prior work in nonparametric image processing and multi-compartment processing to provide computational tools for image interpolation, smoothing, and fusion with fiber orientation mixtures. In contrast to related work on multi-compartment processing, this approach is based on directional measures of divergence and includes data-adaptive extensions for model selection and bilateral filtering. This is useful for reconstructing complex anatomical features in clinical datasets analyzed with the ball-and-sticks model, and our framework’s data-adaptive extensions are potentially useful for general multi-compartment image processing. We experimentally evaluate our approach with both synthetic data from computational phantoms and in vivo clinical data from human subjects. With synthetic data experiments, we evaluate performance based on errors in fiber orientation, volume fraction, compartment count, and tractography-based connectivity. With in vivo data experiments, we first show improved scan-rescan reproducibility and reliability of quantitative fiber bundle metrics, including mean length, volume, streamline count, and mean volume fraction. We then demonstrate the creation of a multi-fiber tractography atlas from a population of 80 human subjects. In comparison to single tensor atlasing, our multi-fiber atlas shows more complete features of known fiber bundles and includes reconstructions of the lateral projections of the corpus callosum and complex fronto-parietal connections of the superior longitudinal fasciculus I, II, and III. PMID:26691524

Posterior root tear fixation of the lateral meniscus combined with arthroscopic ACL double-bundle reconstruction: technical note of a transosseous fixation using the tibial PL tunnel.

PubMed

Forkel, Philipp; Petersen, Wolf

2012-03-01

According to our observation in ACL reconstruction, we find root tears of the posterior horn of the lateral meniscus as a common concomitant injury in ACL-deficient knees. This might be a consequence of initial trauma or of the increased anterior-posterior translation of the tibia and an overload impact on the posterior meniscus root in ACL-deficient knees. A tear of the posterior horn of the medial meniscus causes a 25% increase in peak pressure in the medial compartment compared with that found in the intact condition. The repair restores the peak contact pressure to normal (Allaire et al. in J Bone Joint Surg Am 90(9):1922-1931, [2008]). A tear of the posterior horn of the lateral meniscus might have similar consequences. We hypothesize the surgical anatomical reattachment of the root at the tibia helping to restore knee joint kinematics and helping to advance ACL-graft function. This article presents an arthroscopical technique to reattach the posterior meniscus root in combination with ACL double-bundle reconstruction. The procedure uses the tibial PL tunnel to fix the meniscus suture.

Differential Binary Encoding Method for Calibrating Image Sensors Based on IOFBs

PubMed Central

Fernández, Pedro R.; Lázaro-Galilea, José Luis; Gardel, Alfredo; Espinosa, Felipe; Bravo, Ignacio; Cano, Ángel

2012-01-01

Image transmission using incoherent optical fiber bundles (IOFBs) requires prior calibration to obtain the spatial in-out fiber correspondence necessary to reconstruct the image captured by the pseudo-sensor. This information is recorded in a Look-Up Table called the Reconstruction Table (RT), used later for reordering the fiber positions and reconstructing the original image. This paper presents a very fast method based on image-scanning using spaces encoded by a weighted binary code to obtain the in-out correspondence. The results demonstrate that this technique yields a remarkable reduction in processing time and the image reconstruction quality is very good compared to previous techniques based on spot or line scanning, for example. PMID:22666023

Abnormal tibiofemoral contact stress and its association with altered kinematics after center-center anterior cruciate ligament reconstruction: an in vitro study.

PubMed

Imhauser, Carl; Mauro, Craig; Choi, Daniel; Rosenberg, Eric; Mathew, Stephen; Nguyen, Joseph; Ma, Yan; Wickiewicz, Thomas

2013-04-01

Abnormal tibiofemoral contact stress and aberrant kinematics may influence the progression of osteoarthritis in the anterior cruciate ligament (ACL)-deficient and the ACL-reconstructed knee. However, relationships between contact stress and kinematics after ACL reconstruction are poorly understood. Therefore, we posed the following research questions: (1) How do ACL deficiency and reconstruction affect the kinematics of and contact stress in the tibiofemoral joint? (2) What kinematic differences are associated with abnormal contact stress after ACL reconstruction? Center-center ACL reconstruction will not restore knee kinematics and contact stress. Correlations will exist between abnormal contact stress and aberrant kinematics after ACL reconstruction. Controlled laboratory study. Clinical tests of anterior and rotational stability were simulated on 11 cadaveric knees using an industrial robot. Tests were conducted with the ACL intact, sectioned, and after single-bundle ACL reconstruction using a quadrupled hamstring autograft with tunnels drilled through the center of the native footprints. Kinematics were recorded during the tests. Contact stress was continuously recorded from a stress transducer fixed to the tibial plateau, and mean contact stress was calculated regionally. ACL deficiency resulted in increased mean contact stress in the posterior sectors of the medial and lateral compartments under anterior and rotational loads, respectively. Reconstruction reduced stress in these locations; however, contact stress abnormalities remained. On average, kinematics were overconstrained after ACL reconstruction (≤1.8 mm and ≤2.6° in all directions). However, combinations of overconstrained and underconstrained motions in abduction/adduction and medial-lateral translation in response to combined moments, and anterior-posterior translation, medial-lateral translation, and axial rotation in response to an anterior load were associated with abnormal mean contact stress. ACL reconstruction reduces high stresses generated in the posterior compartment of the ACL-deficient knee. Abnormal contact stress after ACL reconstruction is related to multiplanar variations in knee kinematics. Clinical measures of multiplanar kinematics may help to better characterize the quality of ACL reconstruction. Such measures may help identify patients at increased risk of long-term joint degeneration following this surgery.

Abnormal tibiofemoral contact stress and its association with altered kinematics following center-center ACL reconstruction: an in vitro study

PubMed Central

Imhauser, Carl; Mauro, Craig; Choi, Daniel; Rosenberg, Eric; Mathew, Stephen; Nguyen, Joseph; Ma, Yan; Wickiewicz, Thomas

2014-01-01

Background Abnormal tibiofemoral contact stress and aberrant kinematics may influence the progression of osteoarthritis in the ACL-deficient and the ACL-reconstructed knee. However, relationships between contact stress and kinematics following ACL reconstruction are poorly understood. Therefore, we posed the following research questions: (1) How do ACL deficiency and reconstruction affect kinematics of and contact stress in the tibiofemoral joint? (2) What kinematic differences are associated with abnormal contact stress following ACL reconstruction? Hypothesis/Purpose Center-center ACL reconstruction will not restore knee kinematics and contact stress. Correlations will exist between abnormal contact stress and aberrant kinematics following ACL reconstruction will exist. Study Design Controlled laboratory study Methods Clinical tests of anterior and rotational stability were simulated on eleven cadaveric knees using an industrial robot. Tests were conducted with the ACL intact, sectioned, and after single bundle ACL reconstruction using a quadrupled hamstring autograft with tunnels drilled through the center of the native footprints. Kinematics were recorded during the tests. Contact stress was continuously recorded from a stress transducer fixed to the tibial plateau and mean contact stress was calculated regionally. Results ACL deficiency resulted in increased mean contact stress in the posterior sectors of the medial and lateral compartments under anterior and rotational loads, respectively. Reconstruction reduced stress in these locations; however contact stress abnormalities remained. On average, kinematics were overconstrained following ACL reconstruction (≤1.8mm and ≤2.6° in all directions). However, combinations of overconstrained and underconstrained motions in ab/adduction and medial-lateral translation in response to combined moments, and axial rotation, anterior-posterior and medial-lateral translation in response to an anterior load were associated with abnormal mean contact stress. Conclusions ACL reconstruction reduces high stresses generated in the posterior compartment of the ACL-deficient knee. Abnormal contact stress following ACL reconstruction is related to multiplanar variations in knee kinematics. Clinical Relevance Clinical measures of multiplanar kinematics may help to better characterize the quality of ACL reconstruction. Such measures may help identify those at increased risk of long-term joint degeneration following this surgery. PMID:23470858

Single Molecule Stepping and Structural Dynamics of Myosin X

PubMed Central

Sun, Yujie; Sato, Osamu; Ruhnow, Felix; Arsenault, Mark E.; Ikebe, Mitsuo; Goldman, Yale E.

2010-01-01

Myosin X is an unconventional myosin with puzzling motility properties. We studied the motility of dimerized myosin X using single molecule fluorescence techniques – polTIRF, FIONA, and Parallax to measure rotation angles and 3-dimensional position of the molecule during its walk. It was found that Myosin X steps processively in a hand-over-hand manner following a left-handed helical path along both single actin filaments and bundles. Its step size and velocity are smaller on actin bundles than individual filaments, suggesting myosin X often steps onto neighboring filaments in a bundle. The data suggest that a previously postulated single α-helical domain mechanically extends the 3-IQ motif lever arm and either the neck-tail hinge or the tail is flexible. These structural features, in conjunction with the membrane and microtubule binding domains, enable myosin X to perform multiple functions on varied actin structures in cells. PMID:20364131

Nd- And Er-Doped Phosphate Glass For Fiber Laser.

NASA Astrophysics Data System (ADS)

Yamashita, Toshiharu T.

1990-02-01

Laser fibers prepared from Nd- and Er-doped phosphate glass possessing a large stimulated emission cross section have been investigated both in a single fiber and in a fiber bundle. In the single fiber, continuous wave oscillations were successfully obtained at 1.054 p.m and 1.366 µm on a high Nd-doped single-mode fiber of 10 mm in length and also at 1.535 pm in a Er-doped single-mode fiber, sensitized by Nd, Yb. Especially, a low threshold of 1 mw and a high slope-efficiency of 50% were achieved in 1.054 pm laser oscillation on a Nd-doped fiber, end-pumped with a laser diode. A fiber bundle of phosphate glass doped with 8 wt% Nd2O3 yielded an average output power of 100 W at 50 pps where the bundle was 4.6 mm in diameter and was side-pumped with flash lamps.

Is Remnant Preservation Truly Beneficial to Anterior Cruciate Ligament Reconstruction Healing? Clinical and Magnetic Resonance Imaging Evaluations of Remnant-Preserved Reconstruction.

PubMed

Naraoka, Takuya; Kimura, Yuka; Tsuda, Eiichi; Yamamoto, Yuji; Ishibashi, Yasuyuki

2017-04-01

Remnant-preserved anterior cruciate ligament (ACL) reconstruction was introduced to improve clinical outcomes and biological healing. However, the effects of remnant preservation and the influence of the delay from injury until reconstruction on the outcomes of this technique are still uncertain. Purpose/Hypothesis: The purposes of this study were to evaluate whether remnant preservation improved the clinical outcomes and graft incorporation of ACL reconstruction and to examine the influence of the delay between ACL injury and reconstruction on the usefulness of remnant preservation. We hypothesized that remnant preservation improves clinical results and accelerates graft incorporation and that its effect is dependent on the delay between ACL injury and reconstruction. Cohort study; Level of evidence, 2. A total of 151 consecutive patients who underwent double-bundle ACL reconstruction using a semitendinosus graft were enrolled in this study: 74 knees underwent ACL reconstruction without a remnant (or the remnant was <25% of the intra-articular portion of the graft; NR group), while 77 knees underwent ACL reconstruction with remnant preservation (RP group). These were divided into 4 subgroups based on the time from injury to surgery: phase 1 was <3 weeks (n = 24), phase 2 was 3 to less than 8 weeks (n = 70), phase 3 was 8 to 20 weeks (n = 32), and phase 4 was >20 weeks (n = 25). Clinical measurements, including KT-1000 arthrometer side-to-side anterior tibial translation measurements, were assessed at 3, 6, 12, and 24 months after reconstruction. Magnetic resonance imaging evaluations of graft maturation and graft-tunnel integration of the anteromedial and posterolateral bundles were assessed at 3, 6, and 12 months after reconstruction. There was no difference in side-to-side anterior tibial translation between the NR and RP groups. There was also no difference in graft maturation between the 2 groups. Furthermore, the time from ACL injury until reconstruction did not affect graft maturation, except in the case of very long delays before reconstruction (phase 4). Graft-tunnel integration was significantly increased in both groups in a time-dependent manner. However, there was no difference between the NR and RP groups. Remnant preservation did not improve knee stability at 2 years after ACL reconstruction. Furthermore, remnant preservation did not accelerate graft incorporation, especially during the acute and subacute injury phases.

Lateral Intercondylar Ridge: Is it a reliable landmark for femoral ACL insertion?: An anatomical study.

PubMed

Bhattacharyya, Rahul; Ker, Andrew; Fogg, Quentin; Spencer, Simon J; Joseph, Jibu

2018-02-01

Incorrect femoral tunnel placement is the most common cause of graft failure during Anterior Cruciate Ligament (ACL) Reconstruction. A reliable landmark can minimize errors. To identify whether the Lateral Intercondylar Ridge (LIR) is a consistent anatomical structure and define its relationship with the femoral ACL insertion. Phase 1: we studied 23 femoral dry bone specimens macroscopically. Using a digital microscribe, the medial surface of the lateral femoral condyle was reconstructed (3D) to evaluate whether there was an identifiable bony ridge. Phase 2: 7 cadaveric specimens with intact soft tissues were dissected to identify the femoral ACL insertion. A 3D reconstruction of the femoral ACL insertion and the surface allowed us to define the relationship between the LIR and the ACL insertion. All specimens had a defined LIR on the medial surface of the lateral femoral condyle. The ridge was consistently located just anterior to the femoral ACL insertion. The ACL footprint was present in the depression between the ridge and the Inferior Articular Cartilage Margin (IACM). The mean distance from the midpoint of the IACM to the LIR was 10.1 mm. This is the first study to use the microscribe to digitally reconstruct the medial surface of the lateral femoral condyle. It shows that the LIR is a consistent anatomical structure that defines the anterior margin of the femoral ACL insertion, which guides femoral tunnel placement. Our findings support the ruler technique, which is a commonly used method for anatomic single bundle ACL reconstruction. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Optical absorption and thermal transport of individual suspended carbon nanotube bundles.

PubMed

Hsu, I-Kai; Pettes, Michael T; Bushmaker, Adam; Aykol, Mehmet; Shi, Li; Cronin, Stephen B

2009-02-01

A focused laser beam is used to heat individual single-walled carbon nanotube bundles bridging two suspended microthermometers. By measurement of the temperature rise of the two thermometers, the optical absorption of 7.4-10.3 nm diameter bundles is found to be between 0.03 and 0.44% of the incident photons in the 0.4 microm diameter laser spot. The thermal conductance of the bundle is obtained with the additional measurement of the temperature rise of the nanotubes in the laser spot from shifts in the Raman G band frequency. According to the nanotube bundle diameter determined by transmission electron microscopy, the thermal conductivity is obtained.

Bundled payments in orthopedic surgery.

PubMed

Bushnell, Brandon D

2015-02-01

As a result of reading this article, physicians should be able to: 1. Describe the concept of bundled payments and the potential applications of bundled payments in orthopedic surgery. 2. For specific situations, outline a clinical episode of care, determine the participants in a bundling situation, and define care protocols and pathways. 3. Recognize the importance of resource utilization management, quality outcome measurement, and combined economic-clinical value in determining the value of bundled payment arrangements. 4. Identify the implications of bundled payments for practicing orthopedists, as well as the legal issues and potential future directions of this increasingly popular alternative payment method. Bundled payments, the idea of paying a single price for a bundle of goods and services, is a financial concept familiar to most American consumers because examples appear in many industries. The idea of bundled payments has recently gained significant momentum as a financial model with the potential to decrease the significant current costs of health care. Orthopedic surgery as a field of medicine is uniquely positioned for success in an environment of bundled payments. This article reviews the history, logistics, and implications of the bundled payment model relative to orthopedic surgery. Copyright 2015, SLACK Incorporated.

Arthroscopic and 3D CT Scan Evaluation of Femoral Footprint of the Anterior Cruciate Ligament in Chronic ACL Deficient Knees.

PubMed

Das, Anupam; Yadav, C S; Gamanagatti, Shivanand; Pandey, R M; Mittal, Ravi

2018-06-13

The outcome of single-bundle anterior cruciate ligament (ACL) reconstruction depends largely on the anatomic placement of bone tunnel. The lateral intercondylar ridge (LIR) and bifurcate ridge (BR) are useful bony landmarks for femoral tunnel placement. The purpose of our study was to compare the bony landmarks of ACL footprint on femur by three-dimensional computed tomography (3D CT) scan and arthroscopy in chronic ACL-deficient knees. Fifty patients above 18 years of age who were diagnosed of having ACL tear were selected for the study. All the cases were more than 6 months old since the injury. Preoperative 3D CT scan of the affected knee was obtained for each of them. They underwent single-bundle anatomic ACL reconstruction. Measurements were done on the preoperative 3D CT and arthroscopy to quantify the position of the LIR and BR. The proximodistal distance of lateral femoral condyle was 21.41+/-2.5 mm on CT scan and 22.02+/-2.02 mm on arthroscopy. On preoperative 3D CT scan, the midpoint of the LIR was found to be located at a mean distance of 11.17±2.11 mm from the proximal margin of the lateral femoral condyle. On arthroscopy, it was at 10.18+/-1.52 mm from the proximal margin the lateral femoral condyle. The "bifurcate ridge"(BR) was not visible in any of the cases during arthroscopy or CT scan. We concluded that LIR is an easily identifiable bony landmark on arthroscopy in all cases. It can also be identified on CT scans. BR is not identified both on arthroscopy and CT scans in chronic ACL tears. The arthroscopic measurements of bony landmarks are quite close to those of CT scan. Midpoint of LIR is at 52.185% of the proximodistal distance on CT scan evaluation and it is at 46.21% on arthroscopic evaluation. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Right Atrial Anomalous Muscle Bundle Presenting with Acute Superior Vena Cava Syndrome and Pulmonary Embolism: Surgical Management.

PubMed

Madjarov, Jeko M; Katz, Michael G; Madjarova, Sophia; Madzharov, Svetozar; Arko, Frank R; Miller, David W; Robicsek, Francis

2018-05-21

An anomalous muscle bundle crossing the right atrial cavity represents a pathological finding with unproved clinical significance. This congenital anomaly may be difficult to recognize via echocardiography and could be confused with other intra-cavitary lesions. We report a case of a 53-year-old female presented to the cardio-vascular service with acute superior vena cava syndrome and sub-massive pulmonary embolism. The patient underwent venography confirming superior vena cava stenosis. A ventilation/perfusion lung scan showed two sizable perfusion defects due to pulmonary embolism. MRI and echocardiography imaging demonstrated right atrium mass. Surgery was then carried out using standard cardiopulmonary bypass; right atrial muscle bundle was excised and superior vena cava reconstruction was performed. The patient was discharged uneventfully and remains symptom-free at two years follow-up. In cases of nonmalignant pathology of superior vena cava syndrome, appropriate studies should be conducted to exclude potential congenital abnormalities such as this anomalous muscle bundle in the right atrium. Open heart surgery is a viable treatment option in select cases. Published by Elsevier Inc.

Matrix remodeling between cells and cellular interactions with collagen bundle

NASA Astrophysics Data System (ADS)

Kim, Jihan; Sun, Bo

When cells are surrounded by complex environment, they continuously probe and interact with it by applying cellular traction forces. As cells apply traction forces, they can sense rigidity of their local environment and remodel the matrix microstructure simultaneously. Previous study shows that single human carcinoma cell (MDA-MB-231) remodeled its surrounding extracellular matrix (ECM) and the matrix remodeling was reversible. In this study we examined the matrix microstructure between cells and cellular interaction between them using quantitative confocal microscopy. The result shows that the matrix microstructure is the most significantly remodeled between cells consisting of aligned, and densified collagen fibers (collagen bundle)., the result shows that collagen bundle is irreversible and significantly change micromechanics of ECM around the bundle. We further examined cellular interaction with collagen bundle by analyzing dynamics of actin and talin formation along with the direction of bundle. Lastly, we analyzed dynamics of cellular protrusion and migrating direction of cells along the bundle.

Reinforcement of single-walled carbon nanotube bundles by intertube bridging

NASA Astrophysics Data System (ADS)

Kis, A.; Csányi, G.; Salvetat, J.-P.; Lee, Thien-Nga; Couteau, E.; Kulik, A. J.; Benoit, W.; Brugger, J.; Forró, L.

2004-03-01

During their production, single-walled carbon nanotubes form bundles. Owing to the weak van der Waals interaction that holds them together in the bundle, the tubes can easily slide on each other, resulting in a shear modulus comparable to that of graphite. This low shear modulus is also a major obstacle in the fabrication of macroscopic fibres composed of carbon nanotubes. Here, we have introduced stable links between neighbouring carbon nanotubes within bundles, using moderate electron-beam irradiation inside a transmission electron microscope. Concurrent measurements of the mechanical properties using an atomic force microscope show a 30-fold increase of the bending modulus, due to the formation of stable crosslinks that effectively eliminate sliding between the nanotubes. Crosslinks were modelled using first-principles calculations, showing that interstitial carbon atoms formed during irradiation in addition to carboxyl groups, can independently lead to bridge formation between neighbouring nanotubes.

Tin-oxide-coated single-walled carbon nanotube bundles supporting platinum electrocatalysts for direct ethanol fuel cells.

PubMed

Hsu, Ryan S; Higgins, Drew; Chen, Zhongwei

2010-04-23

Novel tin-oxide (SnO(2))-coated single-walled carbon nanotube (SWNT) bundles supporting platinum (Pt) electrocatalysts for ethanol oxidation were developed for direct ethanol fuel cells. SnO(2)-coated SWNT (SnO(2)-SWNT) bundles were synthesized by a simple chemical-solution route. SnO(2)-SWNT bundles supporting Pt (Pt/SnO(2)-SWNTs) electrocatalysts and SWNT-supported Pt (Pt/SWNT) electrocatalysts were prepared by an ethylene glycol reduction method. The catalysts were physically characterized using TGA, XRD and TEM and electrochemically evaluated through cyclic voltammetry experiments. The Pt/SnO(2)-SWNTs showed greatly enhanced electrocatalytic activity for ethanol oxidation in acid medium, compared to the Pt/SWNT. The optimal SnO(2) loading of Pt/SnO(2)-SWNT catalysts with respect to specific catalytic activity for ethanol oxidation was also investigated.

Episodic payments (bundling): PART I.

PubMed

Jacofsky, D J

2017-10-01

Episodic, or bundled payments, is a concept now familiar to most in the healthcare arena, but the models are often misunderstood. Under a traditional fee-for-service model, each provider bills separately for their services which creates financial incentives to maximise volumes. Under a bundled payment, a single entity, often referred to as a convener (maybe the hospital, the physician group, or a third party) assumes the risk through a payer contract for all services provided within a defined episode of care, and receives a single (bundled) payment for all services provided for that episode. The time frame around the intervention is variable, but defined in advance, as are included and excluded costs. Timing of the actual payment in a bundle may either be before the episode occurs (prospective payment model), or after the end of the episode through a reconciliation (retrospective payment model). In either case, the defined costs over the defined time frame are borne by the convener. Cite this article: Bone Joint J 2017;99-B:1280-5. ©2017 The British Editorial Society of Bone & Joint Surgery.

A single charge in the actin binding domain of fascin can independently tune the linear and non-linear response of an actin bundle network.

PubMed

Maier, M; Müller, K W; Heussinger, C; Köhler, S; Wall, W A; Bausch, A R; Lieleg, O

2015-05-01

Actin binding proteins (ABPs) not only set the structure of actin filament assemblies but also mediate the frequency-dependent viscoelastic moduli of cross-linked and bundled actin networks. Point mutations in the actin binding domain of those ABPs can tune the association and dissociation dynamics of the actin/ABP bond and thus modulate the network mechanics both in the linear and non-linear response regime. We here demonstrate how the exchange of a single charged amino acid in the actin binding domain of the ABP fascin triggers such a modulation of the network rheology. Whereas the overall structure of the bundle networks is conserved, the transition point from strain-hardening to strain-weakening sensitively depends on the cross-linker off-rate and the applied shear rate. Our experimental results are consistent both with numerical simulations of a cross-linked bundle network and a theoretical description of the bundle network mechanics which is based on non-affine bending deformations and force-dependent cross-link dynamics.

The challenge of mapping the human connectome based on diffusion tractography.

PubMed

Maier-Hein, Klaus H; Neher, Peter F; Houde, Jean-Christophe; Côté, Marc-Alexandre; Garyfallidis, Eleftherios; Zhong, Jidan; Chamberland, Maxime; Yeh, Fang-Cheng; Lin, Ying-Chia; Ji, Qing; Reddick, Wilburn E; Glass, John O; Chen, David Qixiang; Feng, Yuanjing; Gao, Chengfeng; Wu, Ye; Ma, Jieyan; Renjie, H; Li, Qiang; Westin, Carl-Fredrik; Deslauriers-Gauthier, Samuel; González, J Omar Ocegueda; Paquette, Michael; St-Jean, Samuel; Girard, Gabriel; Rheault, François; Sidhu, Jasmeen; Tax, Chantal M W; Guo, Fenghua; Mesri, Hamed Y; Dávid, Szabolcs; Froeling, Martijn; Heemskerk, Anneriet M; Leemans, Alexander; Boré, Arnaud; Pinsard, Basile; Bedetti, Christophe; Desrosiers, Matthieu; Brambati, Simona; Doyon, Julien; Sarica, Alessia; Vasta, Roberta; Cerasa, Antonio; Quattrone, Aldo; Yeatman, Jason; Khan, Ali R; Hodges, Wes; Alexander, Simon; Romascano, David; Barakovic, Muhamed; Auría, Anna; Esteban, Oscar; Lemkaddem, Alia; Thiran, Jean-Philippe; Cetingul, H Ertan; Odry, Benjamin L; Mailhe, Boris; Nadar, Mariappan S; Pizzagalli, Fabrizio; Prasad, Gautam; Villalon-Reina, Julio E; Galvis, Justin; Thompson, Paul M; Requejo, Francisco De Santiago; Laguna, Pedro Luque; Lacerda, Luis Miguel; Barrett, Rachel; Dell'Acqua, Flavio; Catani, Marco; Petit, Laurent; Caruyer, Emmanuel; Daducci, Alessandro; Dyrby, Tim B; Holland-Letz, Tim; Hilgetag, Claus C; Stieltjes, Bram; Descoteaux, Maxime

2017-11-07

Tractography based on non-invasive diffusion imaging is central to the study of human brain connectivity. To date, the approach has not been systematically validated in ground truth studies. Based on a simulated human brain data set with ground truth tracts, we organized an open international tractography challenge, which resulted in 96 distinct submissions from 20 research groups. Here, we report the encouraging finding that most state-of-the-art algorithms produce tractograms containing 90% of the ground truth bundles (to at least some extent). However, the same tractograms contain many more invalid than valid bundles, and half of these invalid bundles occur systematically across research groups. Taken together, our results demonstrate and confirm fundamental ambiguities inherent in tract reconstruction based on orientation information alone, which need to be considered when interpreting tractography and connectivity results. Our approach provides a novel framework for estimating reliability of tractography and encourages innovation to address its current limitations.

Nuclear magnetic resonance of molecular hydrogen trapped in single-walled carbon nanotube bundles.

PubMed

Shiraishi, Masashi; Ata, Masafumi

2002-10-01

Molecular dynamics of hydrogen trapped in single-walled carbon nanotube bundles was analyzed by nuclear magnetic resonance. The chemical shift of hydrogen was about 5.1 ppm at 293 K, which is similar to that of water. The relaxation time, T1, was about 0.1-0.2 s. Values in this work are comparable to those for hydrogen loaded in silica and a-Si.

Three Dimensional Reconstruction Workflows for Lost Cultural Heritage Monuments Exploiting Public Domain and Professional Photogrammetric Imagery

NASA Astrophysics Data System (ADS)

Wahbeh, W.; Nebiker, S.

2017-08-01

In our paper, we document experiments and results of image-based 3d reconstructions of famous heritage monuments which were recently damaged or completely destroyed by the so-called Islamic state in Syria and Iraq. The specific focus of our research is on the combined use of professional photogrammetric imagery and of publicly available imagery from the web for optimally 3d reconstructing those monuments. The investigated photogrammetric reconstruction techniques include automated bundle adjustment and dense multi-view 3d reconstruction using public domain and professional imagery on the one hand and an interactive polygonal modelling based on projected panoramas on the other. Our investigations show that the combination of these two image-based modelling techniques delivers better results in terms of model completeness, level of detail and appearance.

Porosity characterization of fiber-reinforced ceramic matrix composite using synchrotron X-ray computed tomography

NASA Astrophysics Data System (ADS)

Zou, C.; Marrow, T. J.; Reinhard, C.; Li, B.; Zhang, C.; Wang, S.

2016-03-01

The pore structure and porosity of a continuous fiber reinforced ceramic matrix composite has been characterized using high-resolution synchrotron X-ray computed tomography (XCT). Segmentation of the reconstructed tomograph images reveals different types of pores within the composite, the inter-fiber bundle open pores displaying a "node-bond" geometry, and the intra-fiber bundle isolated micropores showing a piping shape. The 3D morphology of the pores is resolved and each pore is labeled. The quantitative filtering of the pores measures a total porosity 8.9% for the composite, amid which there is about 7.1~ 9.3% closed micropores.

Adolescents and female patients are at increased risk for contralateral anterior cruciate ligament reconstruction: a cohort study from the Swedish National Knee Ligament Register based on 17,682 patients.

PubMed

Snaebjörnsson, Thorkell; Hamrin Senorski, Eric; Sundemo, David; Svantesson, Eleonor; Westin, Olof; Musahl, Volker; Alentorn-Geli, Eduard; Samuelsson, Kristian

2017-12-01

The impact of different surgical techniques in index ACL reconstruction for patients undergoing contralateral ACL reconstruction was investigated. The study was based on data from the Swedish National Knee Ligament Register. Patients undergoing index ACL reconstruction and subsequent contralateral ACL reconstruction using hamstring graft under the study period were included. The following variables were evaluated: age at index surgery, gender, concomitant meniscal or cartilage injury registered at index injury, transportal femoral bone tunnel drilling and transtibial femoral bone tunnel drilling. The end-point of primary contralateral ACL surgery was analysed as well as the time-to-event outcomes using survivorship methods including Kaplan-Meier estimation and Cox proportional hazards regression models. A total of 17,682 patients [n = 10,013 males (56.6%) and 7669 females (43.4%)] undergoing primary ACL reconstruction from 1 January 2005 through 31 December 2014 were included in the study. A total of 526 (3.0%) patients [n = 260 males (49.4%) and 266 females (50.6%)] underwent primary contralateral ACL reconstruction after index ACL reconstruction during the study period. Females had a 33.7% greater risk of contralateral ACL surgery [HR 1.337 (95% CI 1.127-1.586); (P = 0 0.001)]. The youngest age group (13-15 years) showed an increased risk of contralateral ACL surgery compared with the reference (36-49) age group [HR 2.771 (95% CI 1.456-5.272); (P = 0.002)]. Decreased risk of contralateral ACL surgery was seen amongst patients with concomitant cartilage injury at index surgery [HR 0.765 (95% CI 0.623-0.939); (P = 0.010)]. No differences in terms of the risk of contralateral ACL surgery were found between anatomic and non-anatomic techniques of primary single-bundle ACL reconstruction, comparing transportal anatomic technique to transtibial non-anatomic, anatomic and partial-anatomic. Age and gender were identified as risk factors for contralateral ACL reconstruction; hence young individuals and females were more prone to undergo contralateral ACL reconstruction. Patients with concomitant cartilage injury at index ACL reconstruction had lower risk for contralateral ACL reconstruction. No significant differences between various ACL reconstruction techniques could be related to increased risk of contralateral ACL reconstruction. Retrospective Cohort Study, Level III.

Orthographic Stereo Correlator on the Terrain Model for Apollo Metric Images

NASA Technical Reports Server (NTRS)

Kim, Taemin; Husmann, Kyle; Moratto, Zachary; Nefian, Ara V.

2011-01-01

A stereo correlation method on the object domain is proposed to generate the accurate and dense Digital Elevation Models (DEMs) from lunar orbital imagery. The NASA Ames Intelligent Robotics Group (IRG) aims to produce high-quality terrain reconstructions of the Moon from Apollo Metric Camera (AMC) data. In particular, IRG makes use of a stereo vision process, the Ames Stereo Pipeline (ASP), to automatically generate DEMs from consecutive AMC image pairs. Given camera parameters of an image pair from bundle adjustment in ASP, a correlation window is defined on the terrain with the predefined surface normal of a post rather than image domain. The squared error of back-projected images on the local terrain is minimized with respect to the post elevation. This single dimensional optimization is solved efficiently and improves the accuracy of the elevation estimate.

Photoacoustic endoscopy probe using a coherent fibre-optic bundle and Fabry-Pérot ultrasound sensor (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ansari, Rehman; Beard, Paul C.; Zhang, Edward Z.; Desjardins, Adrien E.

2016-03-01

There is considerable interest in the development of photoacoustic endoscopy (PAE) probes for the clinical assessment of pathologies in the gastrointestinal (GI) tract, guiding minimally invasive laparoscopic surgeries and applications in foetal medicine. However, most previous PAE probes integrate mechanical scanners and piezoelectric transducers at the distal end which can be technically complex, expensive and pose challenges in achieving the necessary level of miniaturisation. We present two novel all-optical forward-viewing endoscopic probes operating in widefield tomography mode that have the potential to overcome these limitations. In one configuration, the probe comprises a transparent 40 MHz Fabry-Pérot ultrasound sensor deposited at the tip of a rigid, 3 mm diameter coherent fibre-optic bundle. In this way, the distal end of coherent fibre bundle acts as a 2D array of wideband ultrasound detectors. In another configuration, an optical relay is used between the distal end face of flexible fibre bundle and the Fabry-Pérot sensor to enlarge the lateral field of view to 6 mm x 6 mm. In both configurations, the pulsed excitation laser beam is full-field coupled into the fibre bundle at the proximal end for uniform backward-mode illumination of the tissue at the probe tip. In order to record the photoacoustic waves arriving at the probe tip, the proximal end of the fibre bundle is optically scanned in 2D with a CW wavelength-tunable interrogation laser beam thereby interrogating different spatial points on the sensor. A time-reversal image reconstruction algorithm was used to reconstruct a 3D image from the detected signals. The 3D field of view of the flexible PAE probe is 6 mm x 6 mm x 6 mm and the axial and lateral spatial resolution is 30 µm and 90 µm, respectively. 3D imaging capability is demonstrated using tissue phantoms, ex vivo tissues and in vivo. To the best of our knowledge, this is the first forward-viewing implementation of a photoacoustic endoscopy probe, and it offers several advantages over previous distal-end scanning probes. These include a high degree of miniaturisation, no moving parts at the distal end and simple and inexpensive fabrication with the potential to realise disposable probes for clinical imaging of the GI tract and other minimally invasive applications.

Role of anthropometric data in the prediction of 4-stranded hamstring graft size in anterior cruciate ligament reconstruction.

PubMed

Ho, Sean Wei Loong; Tan, Teong Jin Lester; Lee, Keng Thiam

2016-03-01

To evaluate whether pre-operative anthropometric data can predict the optimal diameter and length of hamstring tendon autograft for anterior cruciate ligament (ACL) reconstruction. This was a cohort study that involved 169 patients who underwent single-bundle ACL reconstruction (single surgeon) with 4-stranded MM Gracilis and MM Semi-Tendinosus autografts. Height, weight, body mass index (BMI), gender, race, age and -smoking status were recorded pre-operatively. Intra-operatively, the diameter and functional length of the 4-stranded autograft was recorded. Multiple regression analysis was used to determine the relationship between the anthropometric measurements and the length and diameter of the implanted autografts. The strongest correlation between 4-stranded hamstring autograft diameter was height and weight. This correlation was stronger in females than males. BMI had a moderate correlation with the diameter of the graft in females. Females had a significantly smaller graft both in diameter and length when compared with males. Linear regression models did not show any significant correlation between hamstring autograft length with height and weight (p>0.05). Simple regression analysis demonstrated that height and weight can be used to predict hamstring graft diameter. The following regression equation was obtained for females: Graft diameter=0.012+0.034*Height+0.026*Weight (R2=0.358, p=0.004) The following regression equation was obtained for males: Graft diameter=5.130+0.012*Height+0.007*Weight (R2=0.086, p=0.002). Pre-operative anthropometric data has a positive correlation with the diameter of 4 stranded hamstring autografts but no significant correlation with the length. This data can be utilised to predict the autograft diameter and may be useful for pre-operative planning and patient counseling for graft selection.

Comparison of Clinical Results, Second-Look Arthroscopic Findings, and MRI Findings Between the Transportal and Outside-In Techniques for Double-Bundle Anatomic Anterior Cruciate Ligament Reconstruction: A Prospective, Randomized Controlled Trial With a Minimum 2-Year Follow-up.

PubMed

Kim, Jae Gyoon; Kang, Seung Hoon; Kim, Jun Ho; Lim, Chae Ouk; Wang, Joon Ho

2018-03-01

Although image analysis has shown that the outside-in (OI) technique is associated with different femoral tunnel geometry than the transportal (TP) technique in anatomic anterior cruciate ligament (ACL) reconstruction, it is not known whether clinical results differ between the 2 techniques. To compare clinical results, second-look arthroscopic findings, and magnetic resonance imaging (MRI) findings between the TP and OI techniques in anatomic double-bundle (DB) ACL reconstruction. Randomized controlled trial; Level of evidence, 2. From November 2010 to March 2013, 128 patients were enrolled in this study and were randomly assigned to either the TP group (64 patients) or the OI group (64 patients), and DB ACL reconstructions were performed. At the minimum 2-year follow-up (34.9 ± 10.9 months), 111 patients (86.7%) were evaluated with multiple clinical scores and stability tests (KT-2000 arthrometer, Lachman test, and pivot-shift test). Ninety-three knees were evaluated for graft continuity, graft tension, and synovialization by use of second-look arthroscopy. Seventy-eight knees were evaluated on MRI for graft continuity, femoral graft tunnel healing, and graft signal/noise quotient (SNQ). The primary outcome was KT-2000 arthrometer results. Results were compared between the TP and OI groups. No significant differences were found between the 2 groups in terms of KT-2000 arthrometer results, which was the primary outcome, and other clinical results, with the exception of the postoperative functional test of International Knee Documentation Committee (IKDC) objective score. The ratio of grade A and B on the postoperative functional test of IKDC objective score was significantly larger for the OI group (51/58) than the TP group (36/53) ( P = .005). The second-look arthroscopic findings were not significantly different between the 2 groups in either bundle ( P > .05). In addition, MRI findings did not differ significantly between the 2 groups ( P > .05). With the exception of the functional test of IKDC objective score, we found that clinical results, second-look arthroscopic findings, and MRI findings did not differ significantly between the OI and TP techniques for anatomic ACL reconstruction, although femoral tunnel geometries differed significantly between the 2 techniques.

Helium Adsorption on Carbon Nanotube Bundles with Different Diameters:. Molecular Dynamics Simulation

NASA Astrophysics Data System (ADS)

Majidi, R.; Karami, A. R.

2013-05-01

We have used molecular dynamics simulation to study helium adsorption capacity of carbon nanotube bundles with different diameters. Homogeneous carbon nanotube bundles of (8,8), (9,9), (10,10), (11,11), and (12,12) single walled carbon nanotubes have been considered. The results indicate that the exohedral adsorption coverage does not depend on the diameter of carbon nanotubes, while the endohedral adsorption coverage is increased by increasing the diameter.

Pulsating flow past a tube bundle

NASA Astrophysics Data System (ADS)

Molochnikov, V. M.; Mikheev, N. I.; Vazeev, T. A.; Paereliy, A. A.

2017-11-01

Visualization of the pulsating cross-flow past the in-line and staggered tube bundles has been performed. The frequency and amplitude of forced flow pulsations and the tube pitch in the bundle varied in the experiments. The main attention was focused on the flow pattern in the near wake of the third-row tube. The most indicative regimes of flow past a tube in a bundle have been revealed depending on forced flow unsteadiness parameters. The obtained data have been generalized in the flow maps in the space of dimensionless frequency (Strouhal number, St) and relative pulsation amplitude, β, individually for the in-line and staggered tube arrangement. Three most indicative regimes of pulsating flow past the tubes in a bundle have been singled out in each flow map.

Anatomic single-bundle anterior cruciate ligament reconstruction improves walking economy: hamstrings tendon versus patellar tendon grafts.

PubMed

Iliopoulos, Efthymios; Galanis, Nikiforos; Zafeiridis, Andreas; Iosifidis, Michael; Papadopoulos, Pericles; Potoupnis, Michael; Geladas, Nikolaos; Vrabas, Ioannis S; Kirkos, John

2017-10-01

Anterior cruciate ligament (ACL) injury is associated with a pathologic gait pattern and increased energy cost during locomotion. ACL reconstruction could improve the gait pattern. Hamstrings tendon (HAM) and bone-patellar tendon-bone (BPTB) grafts are usually used for reconstruction. The aim of this study was to compare the efficacy of anatomic ACL reconstruction with HAM and BPTB grafts on improving and normalizing the energy cost and physiologic reserves during flat, uphill, and downhill walking. Twenty male subjects with unilateral ACL injuries were randomly assigned to ACL reconstruction with a HAM (n = 10) or BPTB (n = 10) graft. Ten matched controls were also enrolled. All participants performed three 8-min walking tasks at 0, +10, and -10 % gradients before and 9 months after surgery. Energy cost (oxygen consumption, VO 2 ), heart rate (HR), and ventilation (VE) were measured. Lysholm/IKDC scores were recorded. Pre-operatively, VO 2 , HR, and VE were higher in the HAM and BPTB groups than in controls during walking at 0, +10, and -10 % gradients (p < 0.001-0.01). Post-operatively, both HAM and BPTB groups showed reduced VO 2 , HR, and VE during the three walking tasks (p < 0.001-0.01). Although the post-operative VO 2 in both surgical groups reached 90-95 % of the normative (control) value during walking, it remained elevated against the value observed in controls (p < 0.001-0.01). The HAM and BPTB groups showed no differences in post-surgical VO 2 or HR during walking at all three gradients. Anatomic ACL reconstruction with either HAM or BPTB graft resulted in similar short-term improvements in energy cost and nearly normalized locomotion economy and cardiorespiratory reserves during flat, uphill, and downhill walking. The improved locomotion economy is an additional benefit of anatomic ACL reconstruction, irrespective of the type of graft used, that the orthopaedic surgeons should consider. II.

The use of computer imaging techniques to visualize cardiac muscle cells in three dimensions.

PubMed

Marino, T A; Cook, P N; Cook, L T; Dwyer, S J

1980-11-01

Atrial muscle cells and atrioventricular bundle cells were reconstructed using a computer-assisted three-dimensional reconstruction system. This reconstruction technique permitted these cells to be viewed from any direction. The cell surfaces were approximated using triangular tiles, and this optimization technique for cell reconstruction allowed for the computation of cell surface area and cell volume. A transparent mode is described which enables the investigator to examine internal cellular features such as the shape and location of the nucleus. In addition, more than one cell can be displayed simultaneously, and, therefore, spatial relationships are preserved and intercellular relationships viewed directly. The use of computer imaging techniques allows for a more complete collection of quantitative morphological data and also the visualization of the morphological information gathered.

Actin-binding proteins sensitively mediate F-actin bundle stiffness

NASA Astrophysics Data System (ADS)

Claessens, Mireille M. A. E.; Bathe, Mark; Frey, Erwin; Bausch, Andreas R.

2006-09-01

Bundles of filamentous actin (F-actin) form primary structural components of a broad range of cytoskeletal processes including filopodia, sensory hair cell bristles and microvilli. Actin-binding proteins (ABPs) allow the cell to tailor the dimensions and mechanical properties of the bundles to suit specific biological functions. Therefore, it is important to obtain quantitative knowledge on the effect of ABPs on the mechanical properties of F-actin bundles. Here we measure the bending stiffness of F-actin bundles crosslinked by three ABPs that are ubiquitous in eukaryotes. We observe distinct regimes of bundle bending stiffness that differ by orders of magnitude depending on ABP type, concentration and bundle size. The behaviour observed experimentally is reproduced quantitatively by a molecular-based mechanical model in which ABP shearing competes with F-actin extension/compression. Our results shed new light on the biomechanical function of ABPs and demonstrate how single-molecule properties determine mesoscopic behaviour. The bending mechanics of F-actin fibre bundles are general and have implications for cytoskeletal mechanics and for the rational design of functional materials.

Tunneling effects in the kinetics of helium and hydrogen isotopes desorption from single-walled carbon nanotube bundles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Danilchenko, B. A., E-mail: danil@iop.kiev.ua; Yaskovets, I. I.; Uvarova, I. Y.

2014-04-28

The kinetics of desorption both helium isotopes and molecules of hydrogen and deuterium from open-ended or γ-irradiated single-walled carbon nanotube bundles was investigated in temperature range of 10–300 K. The gases desorption rates obey the Arrhenius law at high temperatures, deviate from it with temperature reduction and become constant at low temperatures. These results indicate the quantum nature of gas outflow from carbon nanotube bundles. We had deduced the crossover temperature below which the quantum corrections to the effective activation energy of desorption become significant. This temperature follows linear dependence against the inverse mass of gas molecule and is consistent withmore » theoretical prediction.« less

An Efficient Bundle Adjustment Model Based on Parallax Parametrization for Environmental Monitoring

NASA Astrophysics Data System (ADS)

Chen, R.; Sun, Y. Y.; Lei, Y.

2017-12-01

With the rapid development of Unmanned Aircraft Systems (UAS), more and more research fields have been successfully equipped with this mature technology, among which is environmental monitoring. One difficult task is how to acquire accurate position of ground object in order to reconstruct the scene more accurate. To handle this problem, we combine bundle adjustment method from Photogrammetry with parallax parametrization from Computer Vision to create a new method call APCP (aerial polar-coordinate photogrammetry). One impressive advantage of this method compared with traditional method is that the 3-dimensional point in space is represented using three angles (elevation angle, azimuth angle and parallax angle) rather than the XYZ value. As the basis for APCP, bundle adjustment could be used to optimize the UAS sensors' pose accurately, reconstruct the 3D models of environment, thus serving as the criterion of accurate position for monitoring. To verity the effectiveness of the proposed method, we test on several UAV dataset obtained by non-metric digital cameras with large attitude angles, and we find that our methods could achieve 1 or 2 times better efficiency with no loss of accuracy than traditional ones. For the classical nonlinear optimization of bundle adjustment model based on the rectangular coordinate, it suffers the problem of being seriously dependent on the initial values, making it unable to converge fast or converge to a stable state. On the contrary, APCP method could deal with quite complex condition of UAS when conducting monitoring as it represent the points in space with angles, including the condition that the sequential images focusing on one object have zero parallax angle. In brief, this paper presents the parameterization of 3D feature points based on APCP, and derives a full bundle adjustment model and the corresponding nonlinear optimization problems based on this method. In addition, we analyze the influence of convergence and dependence on the initial values through math formulas. At last this paper conducts experiments using real aviation data, and proves that the new model can effectively solve bottlenecks of the classical method in a certain degree, that is, this paper provides a new idea and solution for faster and more efficient environmental monitoring.

Patterned growth of carbon nanotubes over vertically aligned silicon nanowire bundles for achieving uniform field emission.

PubMed

Hung, Yung-Jr; Huang, Yung-Jui; Chang, Hsuan-Chen; Lee, Kuei-Yi; Lee, San-Liang

2014-01-01

A fabrication strategy is proposed to enable precise coverage of as-grown carbon nanotube (CNT) mats atop vertically aligned silicon nanowire (VA-SiNW) bundles in order to realize a uniform bundle array of CNT-SiNW heterojunctions over a large sample area. No obvious electrical degradation of as-fabricated SiNWs is observed according to the measured current-voltage characteristic of a two-terminal single-nanowire device. Bundle arrangement of CNT-SiNW heterojunctions is optimized to relax the electrostatic screening effect and to maximize the field enhancement factor. As a result, superior field emission performance and relatively stable emission current over 12 h is obtained. A bright and uniform fluorescent radiation is observed from CNT-SiNW-based field emitters regardless of its bundle periodicity, verifying the existence of high-density and efficient field emitters on the proposed CNT-SiNW bundle arrays.

[Intrarenal smooth muscle: histology of a complex urodymamic machine].

PubMed

Arias, L F; Ortiz-Arango, N

2013-03-01

To know better the microscopic arrangement of the bundles of smooth muscle in the human renal parenchyma, their distribution and anatomical relationships, trying to make a reconstruction of this muscular system. Five adult human kidneys and one fetal kidney were processed "in toto" with cross sections every 300μm. In the histological sections we identify the smooth muscle fibers trying to determine its insertion, course and anatomical relationship with other structures of the kidney tissue. There are bundles of smooth muscle fibers of variable thickness parallel to the edges of the medullary pyramids, bundles that surrounding the medulla in a spiral course, and bundles that accompany arcuate vessels, the latter being the most abundant and easy to identify. These groups of muscle fibers do not have a precise or constant insertion site, their periodicity is not homogeneous and they are not a direct extension of the muscle of the renal pelvis, although some bundles are in contact with it. There are also unusual and inconstant small muscle fibers no associated to vessels in the interstitium of the cortex and, exceptionally, in the medulla. There is a complex microscopic system of smooth muscle fibers that partially surround the renal medulla and are related to renal pelvic muscles without a direct continuity with them. Although this small muscular system is under-recognized, could be very important in urodynamics. Copyright © 2012 AEU. Published by Elsevier Espana. All rights reserved.

Ab initio density functional theory investigation of crystalline bundles of polygonized single-walled silicon carbide nanotubes

NASA Astrophysics Data System (ADS)

Moradian, Rostam; Behzad, Somayeh; Chegel, Raad

2008-11-01

By using ab initio density functional theory, the structural characterizations and electronic properties of two large-diameter (13, 13) and (14, 14) armchair silicon carbide nanotube (SiCNT) bundles are investigated. Full structural optimizations show that the cross sections of these large-diameter SiCNTs in the bundles have a nearly hexagonal shape. The effects of inter-tube coupling on the electronic dispersions of large-diameter SiCNT bundles are demonstrated. By comparing the band structures of the triangular lattices of (14, 14) SiCNTs with nearly hexagonal and circular cross sections we found that the polygonization of the tubes in the bundle leads to a further dispersion of the occupied bands and an increase in the bandgap by 0.18 eV.

Ab initio density functional theory investigation of crystalline bundles of polygonized single-walled silicon carbide nanotubes.

PubMed

Moradian, Rostam; Behzad, Somayeh; Chegel, Raad

2008-11-19

By using ab initio density functional theory, the structural characterizations and electronic properties of two large-diameter (13, 13) and (14, 14) armchair silicon carbide nanotube (SiCNT) bundles are investigated. Full structural optimizations show that the cross sections of these large-diameter SiCNTs in the bundles have a nearly hexagonal shape. The effects of inter-tube coupling on the electronic dispersions of large-diameter SiCNT bundles are demonstrated. By comparing the band structures of the triangular lattices of (14, 14) SiCNTs with nearly hexagonal and circular cross sections we found that the polygonization of the tubes in the bundle leads to a further dispersion of the occupied bands and an increase in the bandgap by 0.18 eV.

Intra-surgical total and re-constructible pathological prostate examination for safer margins and nerve preservation (Istanbul preserve).

PubMed

Öbek, Can; Saglican, Yesim; Ince, Umit; Argun, Omer Burak; Tuna, Mustafa Bilal; Doganca, Tunkut; Tufek, Ilter; Keskin, Selcuk; Kural, Ali Riza

2018-04-01

To demonstrate a novel frozen section analysis technique during robot assisted radical prostatectomy with 2 distinct advantages: evaluation of the entire circumference and easier reconstruction for whole mount evaluation. Istanbul Preserve was performed on patients who underwent robotic prostatectomy with nerve sparing between 10/2014 and 7/2016. Gland was sectioned at 3-4mm intervals from apex to bladder neck. Entire tissue representing margins (except for the most anterior portion) was circumferentially excised and microscopically analyzed. In margin positivity, approach was individualized based on extent of positive margin and Gleason pattern. A matched cohort was established for comparison. Retrospective analysis of a prospectively maintained database was performed. Impact of FSA on PSM rate was primarily assessed. Data on 170 patients was analyzed. Positive surgical margin was reported in 56(33%) on frozen section. Neurovascular bundle was partially or totally resected in 79% and 18%. Conversion of positive margin to negative was achieved in 85%. Overall positive margin rate decreased from 22.5% to 7.5%. Nerve sparing increased from 87% to 93%. Location of positive margin at frozen was at the neurovascular bundle area in 39%; thus Istanbul Preserve detected 61% additional margin positivity compared to other techniques. Reconstruction for whole mount was easy. Istanbul Preserve is a novel technique for intraoperative FSA during RARP allowing for microscopic examination of the entire prostate for margin status and easy re-construction for whole mount examination. It guarantees safer margins together with increased rate of nerve sparing. Copyright © 2017 Elsevier Inc. All rights reserved.

Brain white matter fiber estimation and tractography using Q-ball imaging and Bayesian MODEL.

PubMed

Lu, Meng

2015-01-01

Diffusion tensor imaging allows for the non-invasive in vivo mapping of the brain tractography. However, fiber bundles have complex structures such as fiber crossings, fiber branchings and fibers with large curvatures that tensor imaging (DTI) cannot accurately handle. This study presents a novel brain white matter tractography method using Q-ball imaging as the data source instead of DTI, because QBI can provide accurate information about multiple fiber crossings and branchings in a single voxel using an orientation distribution function (ODF). The presented method also uses graph theory to construct the Bayesian model-based graph, so that the fiber tracking between two voxels can be represented as the shortest path in a graph. Our experiment showed that our new method can accurately handle brain white matter fiber crossings and branchings, and reconstruct brain tractograhpy both in phantom data and real brain data.

Passive OCT probe head for 3D duct inspection

NASA Astrophysics Data System (ADS)

Ford, Helen D.; Tatam, Ralph P.

2013-09-01

A passive, endoscopic optical coherence tomography (OCT) probe has been demonstrated, incorporating an imaging fibre bundle and 45° conical mirror, and with no electromechanical components at the probe tip. Circular scanning, of the beam projected onto the proximal face of the imaging bundle, produces a corresponding circular scan at the distal end of the bundle. The beam is turned through 90° by the conical mirror and converted into a radially-scanned sample beam, permitting circumferential OCT scanning in quasi-cylindrical ducts. OCT images, displayed as polar plots and as 3D reconstructions, are presented, showing the internal profile of a metallic test sample containing a 660 µm step in the internal wall. Results have been acquired using two methods: one that makes use of multiple beam-circle diameters, and a mechanical ‘pull-back’ technique. The effects of the convex surface of the conical mirror on spatial resolution are discussed, with suggested working distances given for different application regimes.

Treatment Outcome of Reconstruction for Isolated Posterior Cruciate Injury: Subjective and Objective Evaluations.

PubMed

Ochiai, Satoshi; Hagino, Tetsuo; Senga, Shinya; Yamashita, Takashi; Haro, Hirotaka

2018-05-23

There is no consensus regarding the treatment method and outcome of posterior cruciate ligament (PCL) injury. We hypothesized that although the outcome of PCL reconstruction was favorable in terms of knee stability, the outcome was unsatisfactory in terms of patient-based assessments. The purpose of this study is to evaluate the treatment outcomes of knees that underwent reconstruction for PCL injury by subjective and objective assessments, and to analyze the correlation between various assessments. Twenty-three patients who underwent PCL reconstruction were studied. All reconstructions were performed arthroscopically by the single-bundle technique using a hamstring tendon autograft. Patients were evaluated clinically before operation and 24 months after operation using the 36-Item Short Form Health Survey (SF-36) which is a patient-based health assessment survey, Lysholm score, tibial translation ratio, Visual Analogue Scale (VAS) for pain, and range of motion (ROM) in the knee. The correlation of these assessment methods was analyzed. For the SF-36 survey, significant improvement was observed after operation in only 3 of 7 subscales compared with before surgery. Furthermore, the scores reached the national standard scores in only 3 subscales. While the Lysholm score and tibial translation ratio were improved significantly, no significant improvement in the VAS pain score was observed. For ROM assessment, approximately 30% of the patients had flexion restriction after operation, and the degree of restriction correlated positively with the VAS score. The present results indicated that although the outcome of PCL reconstruction was favorable in terms of knee stability and motor function, the outcome was unsatisfactory in terms of patient-based assessments. Since pain associated with flexion restriction appears to be a poor prognostic factor and there is a dissociation between subjective and objective assessments, improvement of the surgical method is necessary. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

New Feature Observed in the Raman Resonance Excitation Profiles of (6 , 5) -Enriched, Selectively Bundled SWCNTs

NASA Astrophysics Data System (ADS)

Hight Walker, A. R.; Simpson, J. R.; Roslyak, O.; Haroz, E.; Telg, H.; Duque, J. G.; Crochet, J. J.; Piryatinski, A.; Doorn, S. K.

Understanding the photophysics of exciton behavior in single wall carbon nanotube (SWCNT) bundles remains important for opto-electronic device applications. We report resonance Raman spectroscopy (RRS) measurements on (6 , 5) -enriched SWCNTs, dispersed in aqueous solutions and separated using density gradient ultracentrifugation into fractions of increasing bundling. Near-IR to UV absorption spectroscopy shows a redshift and broadening of the main excitonic transitions with increasing bundling. A continuously tunable dye laser coupled to a triple-grating spectrometer affords measurement of Raman resonance excitation profiles (REPs) over a range of wavelengths covering the (6 , 5) -E22 range (505 to 585) nm. REPs of both the radial breathing mode (RBM) and G-band reveal a redshifting and broadening of the (6 , 5) E22 transition energy with increasing bundling. Additionally, we observe an unexpected peak in the REP of bundled SWCNTs, which is shifted lower in energy than the main E22 and is anomalously narrow. We compare these observations to a theoretical model that examines the origin of this peak in relation to bundle polarization-enhanced exciton response.

Magnetic actuation of hair cells

NASA Astrophysics Data System (ADS)

Rowland, David; Roongthumskul, Yuttana; Lee, Jae-Hyun; Cheon, Jinwoo; Bozovic, Dolores

2011-11-01

The bullfrog sacculus contains mechanically sensitive hair cells whose stereociliary bundles oscillate spontaneously when decoupled from the overlying membrane. Steady-state offsets on the resting position of a hair bundle can suppress or modulate this native motility. To probe the dynamics of spontaneous oscillation in the proximity of the critical point, we describe here a method for mechanical actuation that avoids loading the bundles or contributing to the viscous drag. Magnetite beads were attached to the tips of the stereocilia, and a magnetic probe was used to impose deflections. This technique allowed us to observe the transition from multi-mode to single-mode state in freely oscillating bundles, as well as the crossover from the oscillatory to the quiescent state.

Irradiated Hamstring Tendon Allograft Versus Autograft for Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction: Midterm Clinical Outcomes.

PubMed

Tian, Shaoqi; Wang, Bin; Liu, Lun; Wang, Yuanhe; Ha, Chengzhi; Li, Qicai; Yang, Xu; Sun, Kang

2016-10-01

Most studies on grafts for anterior cruciate ligament (ACL) reconstruction (ACLR) have been of autografts or nonirradiated allografts with a single-bundle (SB) technique. Outcome reports evaluating anatomic double-bundle (DB) ACLR with a hamstring tendon autograft versus irradiated allograft are rare. To compare the clinical outcomes of arthroscopic anatomic DB ACLR with a hamstring tendon autograft versus irradiated allograft. Randomized controlled trial; Level of evidence, 2. Between 2008 and 2009, a total of 107 patients undergoing arthroscopic DB ACLR were prospectively randomized consecutively into 1 of 2 groups (autograft [Auto] group and irradiated allograft [Ir-Allo] group). All the surgical procedures were performed by the same senior surgeon using the DB reconstruction technique. All irradiated hamstring tendon allografts were sterilized with 2.5 Mrad of irradiation before distribution and were obtained from a single certified tissue bank. Graft fixation on the femoral side was by an Endobutton, and on the tibial side by a bioabsorbable interference screw augmented with a staple. The same rehabilitation protocol was applied to all patients. Before surgery and at a mean of 6.9 years of follow-up, patients were evaluated by the same observer according to objective and subjective clinical evaluations including detailed history, physical examination, radiography, functional knee ligament testing, KT-2000 arthrometer testing, Harner vertical jump and Daniel 1-legged hop tests, Lysholm score, Tegner score, International Knee Documentation Committee (IKDC) standard evaluation form, and Cincinnati knee score. A total of 83 patients (Auto: n = 40 [mean age, 29.2 ± 6.9 years]; Ir-Allo: n = 43 [mean age, 28.6 ± 7.2 years]) fulfilled follow-up and clinical evaluations. No significant differences were found between the 2 groups according to the overall IKDC functional and subjective evaluations as well as testing of activity levels. Significant between-group differences were found when comparing the results at final follow-up according to the Lachman test, anterior drawer test, pivot-shift test, and KT-2000 arthrometer measurements (P < .001). Most importantly, 87.5% of patients in the Auto group and 34.9% in the Ir-Allo group had a side-to-side difference <3 mm. The rate of laxity (side-to-side difference >5 mm) with an irradiated allograft (30.2%) was higher than that with an autograft (7.5%) (P < .001). The failure rate in the Ir-Allo group (30.2%) was higher than that in the Auto group (7.5%) (P < .001). Anterior and rotational stability decreased significantly in the Ir-Allo group; patients in the Ir-Allo group also had a shorter operation time. There were 10.0% (4/40) of patients in the Auto group and 32.6% (19/43) of patients in the Ir-Allo group who had arthritic progression (P < .05). There were no significant differences in postoperative activity levels and functional outcomes between the Auto and Ir-Allo groups. However, a significant increase in anterior and rotational laxity in the Ir-Allo group was found according to evaluations. We do not advocate an irradiated hamstring tendon allograft for DB ACLR. Clinical Trial Register System of The Affiliated Hospital of Qingdao University (qdfy-ky2008-12). © 2016 The Author(s).

The difference in centre position in the ACL femoral footprint inclusive and exclusive of the fan-like extension fibres.

PubMed

Iriuchishima, Takanori; Ryu, Keinosuke; Aizawa, Shin; Fu, Freddie H

2016-01-01

The purpose of this study was to compare the centre position of each anterior cruciate ligament bundle in its femoral footprint in measurements including and excluding the fan-like extension fibres. Fourteen non-paired human cadaver knees were used. All soft tissues around the knee were resected except the ligaments. The ACL was divided into antero-medial (AM) and postero-lateral (PL) bundles according to the difference in tension patterns. The ACL was carefully dissected, and two outlines were made of the periphery of each bundle insertion site: those which included and those which excluded the fan-like extension fibres. An accurate lateral view of the femoral condyle was photographed with a digital camera, and the images were downloaded to a personal computer. The centre position of each bundle, including and excluding the fan-like extension fibres, was measured with ImageJ software (National Institution of Health). Evaluation of the centre position was performed using the modified quadrant method. The centre of the femoral AM bundle including the fan-like extension was located at 28.8% in a shallow-deep direction and 37.2% in a high-low direction. When the AM bundle was evaluated without the fan-like extension, the centre was significantly different at 34.6% in a shallow-deep direction (p = 0.000) and 36% in a high-low direction. The centre of the PL bundle including the fan-like extension was found at 37.1% in a shallow-deep direction and 73.4% in a high-low direction. When the PL bundle was evaluated without the fan-like extension, the centre was significantly different at 42.7% in a shallow-deep direction (p = 0.000) and 69.3% in a high-low direction (p = 0.000). The centre position of the AM and PL bundles in the femoral ACL footprint was significantly different depending on the inclusion or exclusion of the fan-like extension fibres. For the clinical relevance, to reproduce the direct femoral insertion in the anatomical ACL reconstruction, tunnels should be placed relatively shallow and high in the femoral ACL footprint.

Espins and the actin cytoskeleton of hair cell stereocilia and sensory cell microvilli

PubMed Central

Sekerková, Gabriella; Zheng, Lili; Loomis, Patricia A.; Mugnaini, Enrico; Bartles, James R.

2008-01-01

The espins are novel actin-bundling proteins that are produced in multiple isoforms from a single gene. They are present at high concentration in the parallel actin bundle of hair cell stereocilia and are the target of deafness mutations in mice and humans. Espins are also enriched in the microvilli of taste receptor cells, solitary chemoreceptor cells, vomeronasal sensory neurons and Merkel cells, suggesting that espins play important roles in the microvillar projections of vertebrate sensory cells. Espins are potent actin-bundling proteins that are not inhibited by Ca2+. In cells, they efficiently elongate parallel actin bundles and, thereby, help determine the steady-state length of microvilli and stereocilia. Espins bind actin monomer via their WH2 domain and can assemble actin bundles in cells. Certain espin isoforms can also bind phosphatidylinositol 4,5-bisphosphate, profilins or SH3 proteins. These biological activities distinguish espins from other actin-bundling proteins and may make them well-suited to sensory cells. PMID:16909209

Heat Transfer Analysis in Wire Bundles for Aerospace Vehicles

NASA Technical Reports Server (NTRS)

Rickman, S. L.; Iamello, C. J.

2016-01-01

Design of wiring for aerospace vehicles relies on an understanding of "ampacity" which refers to the current carrying capacity of wires, either, individually or in wire bundles. Designers rely on standards to derate allowable current flow to prevent exceedance of wire temperature limits due to resistive heat dissipation within the wires or wire bundles. These standards often add considerable margin and are based on empirical data. Commercial providers are taking an aggressive approach to wire sizing which challenges the conventional wisdom of the established standards. Thermal modelling of wire bundles may offer significant mass reduction in a system if the technique can be generalized to produce reliable temperature predictions for arbitrary bundle configurations. Thermal analysis has been applied to the problem of wire bundles wherein any or all of the wires within the bundle may carry current. Wire bundles present analytical challenges because the heat transfer path from conductors internal to the bundle is tortuous, relying on internal radiation and thermal interface conductance to move the heat from within the bundle to the external jacket where it can be carried away by convective and radiative heat transfer. The problem is further complicated by the dependence of wire electrical resistivity on temperature. Reduced heat transfer out of the bundle leads to higher conductor temperatures and, hence, increased resistive heat dissipation. Development of a generalized wire bundle thermal model is presented and compared with test data. The steady state heat balance for a single wire is derived and extended to the bundle configuration. The generalized model includes the effects of temperature varying resistance, internal radiation and thermal interface conductance, external radiation and temperature varying convective relief from the free surface. The sensitivity of the response to uncertainties in key model parameters is explored using Monte Carlo analysis.

A discrete method for modal analysis of overhead line conductor bundles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Migdalovici, M.A.; Sireteanu, T.D.; Albrecht, A.A.

The paper presents a mathematical model and a semi-analytical procedure to calculate the vibration modes and eigenfrequencies of single or bundled conductors with spacers which are needed for evaluation of the wind induced vibration of conductors and for optimization of spacer-dampers placement. The method consists in decomposition of conductors in modules and the expansion by polynomial series of unknown displacements on each module. A complete system of polynomials are deduced for this by Legendre polynomials. Each module is considered either boundary conditions at the extremity of the module or the continuity conditions between the modules and also a number ofmore » projections of module equilibrium equation on the polynomials from the expansion series of unknown displacement. The global system of the eigenmodes and eigenfrequencies is of the matrix form: A X + {omega}{sup 2} M X = 0. The theoretical considerations are exemplified on one conductor and on bundle of two conductors with spacers. From this, a method for forced vibration calculus of a single or bundled conductors is also presented.« less

Evidence-based care bundles for preventing surgical site infections in spinal instrumentation surgery.

PubMed

Yamada, Koji; Abe, Hiroaki; Higashikawa, Akiro; Tonosu, Juichi; Kuniya, Takashi; Nakajima, Koji; Fujii, Haruko; Niwa, Kazuki; Shinozaki, Tomohiro; Watanabe, Kenichi; Sakae, Tanaka; Okazaki, Hiroshi

2018-05-22

Retrospective study, using prospectively collected data. To evaluate the impact of evidence-based care bundles for preventing surgical site infections (SSI) in spinal instrumentation surgery. About half of all SSIs are preventable via evidence-based methods. For successful SSI prevention, the bacterial load must be minimized, and methicillin-resistant Staphylococcus aureus (MRSA) protection must be maximized. However, it is difficult to cover all of these requirements by single preventative method. We screened consecutive patients scheduled for spinal instrumentation surgeries at a single tertiary referral hospital for high surgical, SSI, and MRSA colonization risks. Evidence-based care bundles were implemented for high risk patients and included: 1) additional vancomycin prophylaxis, 2) diluted povidone-iodine irrigation, and 3) nasal and body decontamination. Patient demographics, comorbidities, operative features, and SSIs reported to the Japanese Nosocomial Infections Surveillance system were prospectively obtained in the same method by the same assessor and were used for the analyses. The results were compared before and after the application of the bundle. There were 1,042 spinal instrumentation surgeries (741 before and 301 after care bundles) performed from November 2010 to December 2015. Of 301 surgeries, 57 cases (18.9%) received care bundles. There were no significant differences in patient backgrounds before and after the intervention. The SSI rate decreased significantly from 3.8% to 0.7% (P < 0.01) after the intervention, with an overall 82% relative risk reduction. A significant protective effect was observed in the multivariate analysis (adjusted odds ratio 0.18, 95% confidence interval: 0.04-0.77, P = 0.02). There were no MRSA-related SSIs among those that received care bundles, even though MRSA was the predominant pathogen in the study population. Evidence-based care bundles, applied in selected high-risk spinal instrumentation cases, minimized bacterial load, maximized MRSA protection, and significantly reduced SSI rates without topical vancomycin powder. 4.

Shape analysis of the cingulum, uncinate and arcuate fasciculi in patients with bipolar disorder

PubMed Central

Sun, Zhong Yi; Houenou, Josselin; Duclap, Delphine; Sarrazin, Samuel; Linke, Julia; Daban, Claire; Hamdani, Nora; d’Albis, Marc-Antoine; Le Corvoisier, Philippe; Guevara, Pamela; Delavest, Marine; Bellivier, Frank; Almeida, Jorge; Versace, Amelia; Poupon, Cyril; Leboyer, Marion; Phillips, Mary; Wessa, Michèle; Mangin, Jean-François

2017-01-01

Background Abnormal maturation of brain connectivity is supposed to underlie the dysfunctional emotion regulation in patients with bipolar disorder (BD). To test this hypothesis, white matter integrity is usually investigated using measures of water diffusivity provided by MRI. Here we consider a more intuitive aspect of the morphometry of the white matter tracts: the shape of the fibre bundles, which is associated with neurodevelopment. We analyzed the shape of 3 tracts involved in BD: the cingulum (CG), uncinate fasciculus (UF) and arcuate fasciculus (AF). Methods We analyzed diffusion MRI data in patients with BD and healthy controls. The fibre bundles were reconstructed using Q-ball–based tractography and automated segmentation. Using Isomap, a manifold learning method, the differences in the shape of the reconstructed bundles were visualized and quantified. Results We included 112 patients and 82 controls in our analysis. We found the left AF of patients to be further extended toward the temporal pole, forming a tighter hook than in controls. We found no significant difference in terms of shape for the left UF, the left CG or the 3 right fasciculi. However, in patients compared with controls, the ventrolateral branch of the left UF in the orbitofrontal region had a tendency to be larger, and the left CG of patients had a tendency to be smaller in the frontal lobe and larger in the parietal lobe. Limitations This was a cross-sectional study. Conclusion Our results suggest neurodevelopmental abnormalities in the left AF in patients with BD. The statistical tendencies observed for the left UF and left CG deserve further study. PMID:28234596

Shape analysis of the cingulum, uncinate and arcuate fasciculi in patients with bipolar disorder.

PubMed

Sun, Zhong Yi; Houenou, Josselin; Duclap, Delphine; Sarrazin, Samuel; Linke, Julia; Daban, Claire; Hamdani, Nora; d'Albis, Marc-Antoine; Le Corvoisier, Philippe; Guevara, Pamela; Delavest, Marine; Bellivier, Frank; Bellivier, Frank; Almeida, Jorge; Versace, Amelia; Poupon, Cyril; Leboyer, Marion; Phillips, Mary; Wessa, Michèle; Mangin, Jean-François

2017-01-01

Abnormal maturation of brain connectivity is supposed to underlie the dysfunctional emotion regulation in patients with bipolar disorder (BD). To test this hypothesis, white matter integrity is usually investigated using measures of water diffusivity provided by MRI. Here we consider a more intuitive aspect of the morphometry of the white matter tracts: the shape of the fibre bundles, which is associated with neurodevelopment. We analyzed the shape of 3 tracts involved in BD: the cingulum (CG), uncinate fasciculus (UF) and arcuate fasciculus (AF). We analyzed diffusion MRI data in patients with BD and healthy controls. The fibre bundles were reconstructed using Q-ball-based tractography and automated segmentation. Using Isomap, a manifold learning method, the differences in the shape of the reconstructed bundles were visualized and quantified. We included 112 patients and 82 controls in our analysis. We found the left AF of patients to be further extended toward the temporal pole, forming a tighter hook than in controls. We found no significant difference in terms of shape for the left UF, the left CG or the 3 right fasciculi. However, in patients compared with controls, the ventrolateral branch of the left UF in the orbitofrontal region had a tendency to be larger, and the left CG of patients had a tendency to be smaller in the frontal lobe and larger in the parietal lobe. This was a cross-sectional study. Our results suggest neurodevelopmental abnormalities in the left AF in patients with BD. The statistical tendencies observed for the left UF and left CG deserve further study.

Influence of screw length and diameter on tibial strain energy density distribution after anterior cruciate ligament reconstruction

NASA Astrophysics Data System (ADS)

Yao, Jie; Kuang, Guan-Ming; Wong, Duo Wai-Chi; Niu, Wen-Xin; Zhang, Ming; Fan, Yu-Bo

2014-04-01

Postoperative tunnel enlargement has been frequently reported after anterior cruciate ligament (ACL) reconstruction. Interference screw, as a surgical implant in ACL reconstruction, may influence natural loading transmission and contribute to tunnel enlargement. The aims of this study are (1) to quantify the alteration of strain energy den sity (SED) distribution after the anatomic single-bundle ACL reconstruction; and (2) to characterize the influence of screw length and diameter on the degree of the SED alteration. A validated finite element model of human knee joint was used. The screw length ranging from 20 to 30mm with screw diameter ranging from 7 to 9 mm were investigated. In the post-operative knee, the SED increased steeply at the extra-articular tunnel aperture under compressive and complex loadings, whereas the SED decreased beneath the screw shaft and nearby the intra-articular tunnel aperture. Increasing the screw length could lower the SED deprivation in the proximal part of the bone tunnel; whereas increasing either screw length or diameter could aggravate the SED deprivation in the distal part of the bone tunnel. Decreasing the elastic modulus of the screw could lower the bone SED deprivation around the screw. In consideration of both graft stability and SED alteration, a biodegradable interference screw with a long length is recommended, which could provide a beneficial mechanical environment at the distal part of the tunnel, and meanwhile decrease the bone-graft motion and synovial fluid propagation at the proximal part of the tunnel. These findings together with the clinical and histological factors could help to improve surgical outcome, and serve as a preliminary knowledge for the following study of biodegradable interference screw. [Figure not available: see fulltext.

Dual-modality endoscopic probe for tissue surface shape reconstruction and hyperspectral imaging enabled by deep neural networks.

PubMed

Lin, Jianyu; Clancy, Neil T; Qi, Ji; Hu, Yang; Tatla, Taran; Stoyanov, Danail; Maier-Hein, Lena; Elson, Daniel S

2018-06-15

Surgical guidance and decision making could be improved with accurate and real-time measurement of intra-operative data including shape and spectral information of the tissue surface. In this work, a dual-modality endoscopic system has been proposed to enable tissue surface shape reconstruction and hyperspectral imaging (HSI). This system centers around a probe comprised of an incoherent fiber bundle, whose fiber arrangement is different at the two ends, and miniature imaging optics. For 3D reconstruction with structured light (SL), a light pattern formed of randomly distributed spots with different colors is projected onto the tissue surface, creating artificial texture. Pattern decoding with a Convolutional Neural Network (CNN) model and a customized feature descriptor enables real-time 3D surface reconstruction at approximately 12 frames per second (FPS). In HSI mode, spatially sparse hyperspectral signals from the tissue surface can be captured with a slit hyperspectral imager in a single snapshot. A CNN based super-resolution model, namely "super-spectral-resolution" network (SSRNet), has also been developed to estimate pixel-level dense hypercubes from the endoscope cameras standard RGB images and the sparse hyperspectral signals, at approximately 2 FPS. The probe, with a 2.1 mm diameter, enables the system to be used with endoscope working channels. Furthermore, since data acquisition in both modes can be accomplished in one snapshot, operation of this system in clinical applications is minimally affected by tissue surface movement and deformation. The whole apparatus has been validated on phantoms and tissue (ex vivo and in vivo), while initial measurements on patients during laryngeal surgery show its potential in real-world clinical applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Reconstruction method for fringe projection profilometry based on light beams.

PubMed

Li, Xuexing; Zhang, Zhijiang; Yang, Chen

2016-12-01

A novel reconstruction method for fringe projection profilometry, based on light beams, is proposed and verified by experiments. Commonly used calibration techniques require the parameters of projector calibration or the reference planes placed in many known positions. Obviously, introducing the projector calibration can reduce the accuracy of the reconstruction result, and setting the reference planes to many known positions is a time-consuming process. Therefore, in this paper, a reconstruction method without projector's parameters is proposed and only two reference planes are introduced. A series of light beams determined by the subpixel point-to-point map on the two reference planes combined with their reflected light beams determined by the camera model are used to calculate the 3D coordinates of reconstruction points. Furthermore, the bundle adjustment strategy and the complementary gray-code phase-shifting method are utilized to ensure the accuracy and stability. Qualitative and quantitative comparisons as well as experimental tests demonstrate the performance of our proposed approach, and the measurement accuracy can reach about 0.0454 mm.

Machine Tests Optical Fibers In Flexure

NASA Technical Reports Server (NTRS)

Darejeh, Hadi; Thomas, Henry; Delcher, Ray

1993-01-01

Machine repeatedly flexes single optical fiber or cable or bundle of optical fibers at low temperature. Liquid nitrogen surrounds specimen as it is bent back and forth by motion of piston. Machine inexpensive to build and operate. Tests under repeatable conditions so candidate fibers, cables, and bundles evaluated for general robustness before subjected to expensive shock and vibration tests.

Single-shot polarimetry imaging of multicore fiber.

PubMed

Sivankutty, Siddharth; Andresen, Esben Ravn; Bouwmans, Géraud; Brown, Thomas G; Alonso, Miguel A; Rigneault, Hervé

2016-05-01

We report an experimental test of single-shot polarimetry applied to the problem of real-time monitoring of the output polarization states in each core within a multicore fiber bundle. The technique uses a stress-engineered optical element, together with an analyzer, and provides a point spread function whose shape unambiguously reveals the polarization state of a point source. We implement this technique to monitor, simultaneously and in real time, the output polarization states of up to 180 single-mode fiber cores in both conventional and polarization-maintaining fiber bundles. We demonstrate also that the technique can be used to fully characterize the polarization properties of each individual fiber core, including eigen-polarization states, phase delay, and diattenuation.

Revision anterior cruciate ligament reconstruction by double-bundle technique using multi-strand semitendinosus tendon.

PubMed

Muneta, Takeshi; Hara, Kenji; Ju, Young-Jin; Mochizuki, Tomoyuki; Morito, Toshiyuki; Yagishita, Kazuyoshi; Sekiya, Ichiro

2010-06-01

The purpose of the study was to compare the outcome of revision anterior cruciate ligament (ACL) reconstruction by the double-bundle (DB) technique using multi-strand semitendinosus tendon with that of primary reconstruction by use of the same technique. The study included 21 patients who underwent revision ACL reconstruction (mean follow-up, 40 months) with the semitendinosus tendon DB technique between 1995 and 2006 and 86 unilateral primary DB ACL reconstructions (mean follow-up, 33 months) between 2000 and 2004. The outcome of both groups was compared based on differences between operated and unoperated limbs and modified International Knee Documentation Committee grades. Both the overall and sports-related subjective scores were evaluated between the 2 groups. The KT measurements (MEDmetric, San Diego, CA) averaged 1.7 mm (SD, 1.8 mm) in the revision group and 1.5 mm (SD, 1.6 mm) in the primary group. There was no significant difference in KT measurements between the 2 groups. The Lachman test was negative in 83% of revision cases and 87% of primary cases; the anterior drawer test was negative in 83% and 91%, respectively, and the pivot-shift test was negative in 78% and 90%, respectively. There was a tendency for a positive pivot-shift test in the revision group being higher. The Lysholm score and subjective recovery score were significantly lower in the revision group. The semitendinosus tendon DB revision procedure provided range of motion and anterior stability comparable to those after primary DB surgery and a comparable return to athletic activities. However, the patients tended to have positive pivot-shift test results. The revision cases were also inferior in terms of the general evaluation of recovery of knee condition. The outcome scores were lower overall in the revision group. Level IV, therapeutic case series. Copyright (c) 2010 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Large-area fluidic assembly of single-walled carbon nanotubes through dip-coating and directional evaporation

NASA Astrophysics Data System (ADS)

Kim, Pilnam; Kang, Tae June

2017-12-01

We present a simple and scalable fluidic-assembly approach, in which bundles of single-walled carbon nanotubes (SWCNTs) are selectively aligned and deposited by directionally controlled dip-coating and solvent evaporation processes. The patterned surface with alternating regions of hydrophobic polydimethyl siloxane (PDMS) (height 100 nm) strips and hydrophilic SiO2 substrate was withdrawn vertically at a constant speed ( 3 mm/min) from a solution bath containing SWCNTs ( 0.1 mg/ml), allowing for directional evaporation and subsequent selective deposition of nanotube bundles along the edges of horizontally aligned PDMS strips. In addition, the fluidic assembly was applied to fabricate a field effect transistor (FET) with highly oriented SWCNTs, which demonstrate significantly higher current density as well as high turn-off ratio (T/O ratio 100) as compared to that with randomly distributed carbon nanotube bundles (T/O ratio <10).

Evidence of Intertube Excitons Observed in the Raman Resonance Excitation Profiles of (6 , 5) -Enriched SWCNT Bundles

NASA Astrophysics Data System (ADS)

Simpson, J. R.; Hight Walker, A. R.; Roslyak, O.; Haroz, E.; Telg, H.; Duque, J. G.; Crochet, J. J.; Piryatinkski, A.; Doorn, S. K.

Understanding the photophysics of exciton behavior in single wall carbon nanotube (SWCNT) bundles remains important for opto-electronic device applications. We report resonance Raman spectroscopy (RRS) measurements on (6 , 5) -enriched SWCNTs, dispersed in aqueous solutions and separated using density gradient ultracentrifugation into fractions of increasing bundle size. Near-IR to UV absorption spectroscopy demonstrates a redshift and broadening of the main excitonic transitions with bundling. A continuously tunable dye laser coupled to a triple-grating spectrometer affords measurement of Raman resonance excitation profiles (REPs) over a range of wavelengths, (505 to 585) nm, covering the (6 , 5) -E22S excitation. REPs of both the radial breathing mode (RBM) and GLO+reveal a redshifting and broadening of the (6 , 5) E22S transition energy with increasing bundle size. Most interestingly, we observe an additional peak in both the RBM and GLO+REPs of bundled SWCNTs, which is shifted lower in energy than the main E22S and is anomalously narrow. We attribute this additional peak to a transverse, intertube exciton.

Composite Service Life Prediction via Fiber Bundle Testing. Evaluation of Testing Equipment and Data Acquisition System

DTIC Science & Technology

1986-12-01

PREDICTION VIA FIBER BUNDLE TESTING-EVALUATION OF TESTING EQUIPMENT JD DATA ACQUISITION SYSTEM PERSONAL AUTHOR(S) Petridis Dimitrios M. i *y?e o j report...experiencing a known number of filament failures per bundle. The results of this investigation are relevant to man-safe applications as in composite pressure...single filament r’iber testing and can become more 29 3> C o - Pwo PwS ?w4 Pw3 Pw2 Pwl PSD Ps5 PS4 Ps3 Ps2 PS! homoiogous correspondence t ~ to Life ( Laqt

Prevalence of Split Nerve Fiber Layer Bundles in Healthy People Imaged with Spectral Domain Optical Coherence Tomography.

PubMed

Gür Güngör, Sirel; Akman, Ahmet; Sarıgül Sezenöz, Almila; Tanrıaşıkı, Gülşah

2016-12-01

The presence of retinal nerve fiber layer (RNFL) split bundles was recently described in normal eyes scanned using scanning laser polarimetry and by histologic studies. Split bundles may resemble RNFL loss in healthy eyes. The aim of our study was to determine the prevalence of nerve fiber layer split bundles in healthy people. We imaged 718 eyes of 359 healthy persons with the spectral domain optical coherence tomography in this cross-sectional study. All eyes had intraocular pressure of 21 mmHg or less, normal appearance of the optic nerve head, and normal visual fields (Humphrey Field Analyzer 24-2 full threshold program). In our study, a bundle was defined as 'split' when there is localized defect not resembling a wedge defect in the RNFL deviation map with a symmetrically divided RNFL appearance on the RNFL thickness map. The classification was performed by two independent observers who used an identical set of reference examples to standardize the classification. Inter-observer consensus was reached in all cases. Bilateral superior split bundles were seen in 19 cases (5.29%) and unilateral superior split was observed in 15 cases (4.16%). In 325 cases (90.52%) there was no split bundle. Split nerve fiber layer bundles, in contrast to single nerve fiber layer bundles, are not common findings in healthy eyes. In eyes with normal optic disc appearance, especially when a superior RNFL defect is observed in RNFL deviation map, the RNLF thickness map and graphs should also be examined for split nerve fiber layer bundles.

A fast bilinear structure from motion algorithm using a video sequence and inertial sensors.

PubMed

Ramachandran, Mahesh; Veeraraghavan, Ashok; Chellappa, Rama

2011-01-01

In this paper, we study the benefits of the availability of a specific form of additional information—the vertical direction (gravity) and the height of the camera, both of which can be conveniently measured using inertial sensors and a monocular video sequence for 3D urban modeling. We show that in the presence of this information, the SfM equations can be rewritten in a bilinear form. This allows us to derive a fast, robust, and scalable SfM algorithm for large scale applications. The SfM algorithm developed in this paper is experimentally demonstrated to have favorable properties compared to the sparse bundle adjustment algorithm. We provide experimental evidence indicating that the proposed algorithm converges in many cases to solutions with lower error than state-of-art implementations of bundle adjustment. We also demonstrate that for the case of large reconstruction problems, the proposed algorithm takes lesser time to reach its solution compared to bundle adjustment. We also present SfM results using our algorithm on the Google StreetView research data set.

Adsorption studies of simple gases on As-produced single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Talapatra, Saikat

Adsorption isotherms measurements were used to study films of Xenon (Xe), Argon (Ar), Methane (CH4), Hydrogen (H2) and Neon (Ne) adsorbed on bundles of as-produced Single Walled Carbon Nanotubes (SWNT). A comparison of the specific surface areas of the SWNT samples measured with these various gases, as well as a comparison of the binding energies measured for each of them on the SWNT bundles; allows us to infer which of the possible groups of adsorption sites on the SWNT bundles are actually occupied by the adsorbed gases. The presence of substeps in the first layer isotherm data establishes the existence of different phases within the first layer film. A detailed comparison of our experimental results to recent computer simulations for these systems is done. This allows us to determine the nature of the phases present in the first layer. Evidence of the formation of a one-dimensional phase in the second layer film (i.e. the film that forms after the entire surface of the bundles is covered by one layer of gas) is observed in these studies. The sharpness of this second layer feature varies as a function of the molecular diameter of the adsorbate.

Morphological size evaluation of the mid-substance insertion areas and the fan-like extension fibers in the femoral ACL footprint.

PubMed

Suruga, Makoto; Horaguchi, Takashi; Iriuchishima, Takanori; Yahagi, Yoshiyuki; Iwama, Genki; Tokuhashi, Yasuaki; Aizawa, Shin

2017-08-01

The purpose of this study was to evaluate the detailed anatomy of the femoral anterior cruciate ligament (ACL) insertion site, with special attention given to the morphology of the mid-substance insertion areas and the fan-like extension fibers. Twenty-three non-paired human cadaver knees were used (7 Males, 16 Females, median age 83, range 69-96). All soft tissues around the knee were resected except the ligaments. The ACL was divided into antero-medial (AM) and postero-lateral (PL) bundles according to the difference in macroscopic tension patterns. The ACL was carefully dissected and two outlines were made of the periphery of each bundle insertion site: those which included and those which excluded the fan-like extension fibers. An accurate lateral view of the femoral condyle was photographed with a digital camera, and the images were downloaded to a personal computer. The area of each bundle, including and excluding the fan-like extension fibers, was measured with Image J software (National Institution of Health). The width and length of the mid-substance insertion sites were also evaluated using same image. The femoral ACL footprint was divided into four regions (mid-substance insertion sites of the AM and PL bundles, and fan-like extensions of the AM and PL bundles). The measured areas of the mid-substance insertion sites of the AM and PL bundles were 35.5 ± 12.5, and 32.4 ± 13.8 mm 2 , respectively. Whole width and length of the mid-substance insertion sites were 5.3 ± 1.4, and 15.5 ± 2.9 mm, respectively. The measured areas of the fan-like extensions of the AM and PL bundles were 27 ± 11.5, and 29.5 ± 12.4 mm 2 , respectively. The femoral ACL footprint was divided into quarters of approximately equal size (mid-substance insertion sites of the AM and PL bundles, and fan-like extensions of the AM and PL bundles). For clinical relevance, to perform highly reproducible anatomical ACL reconstruction, the presence of the fan-like extension fibers should be taken into consideration.

The relationship of lateral anatomic structures to exiting guide pins during femoral tunnel preparation utilizing an accessory medial portal.

PubMed

Farrow, Lutul D; Parker, Richard D

2010-06-01

Anatomic reconstruction of the anterior cruciate ligament through an accessory medial portal has become increasingly popular. The purpose of this study is to describe the relationship of guide pin exit points to the lateral anatomic structures when preparing the anterior cruciate ligament femoral tunnel through an accessory medial portal. We utilized seven fresh frozen cadaveric knees. Utilizing an anteromedial approach, a guide wire was placed into the center of each bundle's footprint. Each guide wire was advanced through the lateral femoral cortex. The guide pins were passed at 90, 110, and 130 degrees of knee flexion. The distances from each guide pin to the closest relevant structures on the lateral side of the knee were measured. At 90 degrees the posterolateral bundle guide pin was closest to the lateral condyle articular cartilage (mean 5.4 +/- 2.2 mm) and gastrocnemius tendon (mean 5.7 +/- 2.1 mm). At 110 degrees the posterolateral bundle pin was closest to the gastrocnemius tendon (mean 4.5 +/- 3.4 mm). At 130 degrees the posterolateral bundle pin was closest to the gastrocnemius tendon (mean 7.2 +/- 5.5 mm) and lateral collateral ligament (mean 6.8 +/- 2.1 mm). At 90 degrees the anteromedial bundle guide pin was closest to the articular cartilage (mean 2.0 +/- 2.0 mm). At 110 degrees the anteromedial bundle pin was closest to the articular cartilage (mean 7.4 +/- 3.5 mm) and gastrocnemius tendon (mean 12.3 +/- 3.1 mm). At 130 degrees the AM bundle pin was closest to the gastrocnemius tendon (mean 8.2 +/- 3.2 mm) and LCL (mean 15.1 +/- 2.9 mm). Neither guide pin (anteromedial or posterolateral bundle) put the peroneal nerve at risk at any knee flexion angle. At low knee flexion angles the anteromedial and posterolateral bundle guide pins closely approximated multiple lateral structures when using an accessory medial arthroscopic portal. Utilizing higher flexion angles increases the margin of error when preparing both femoral tunnels. During preparation of the anterior cruciate ligament femoral tunnel through an accessory anteromedial portal the tunnels should be drilled in at least 110 degrees of knee flexion in order to move guide pin exit points away from important lateral knee structures.

Two-phase pressure drop reduction BWR assembly design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dix, G.E.; Crowther, R.L.; Colby, M.J.

1992-05-12

This patent describes a boiling water reactor having discrete bundles of fuel rods confined within channel enclosed fuel assemblies, an improvement to a fuel bundle assembly for placement in the reactor. It comprises a fuel channel having vertically extending walls forming a continuous channel around a fuel assembly volume, the channel being open at the bottom end for engagement to a lower tie plate and open at the upper end for engagement to an upper tie plate; rods for placement within the chamber, each the rod containing fissile material for producing nuclear reaction when in the presence of sufficient moderatedmore » neutron flux; a lower tie plate for supporting the bundle of rods within the channel, the lower tie plate for supporting the bundle of rods within the channel, the lower tie plate joining the bottom of the channel to close the bottom end of the channel, the lower tie plate providing defined apertures for the inflow of water in the channel between the rods for the generating of steam during the nuclear reaction; the plurality of fuel rods extending from the lower tie plate wherein a single phase region of the water in the bundle is defined to an upward portion of the bundle wherein a two phase region of the water and steam in the bundle is defined during nuclear steam generating reaction in the fuel bundle.« less

The on-orbit calibration of geometric parameters of the Tian-Hui 1 (TH-1) satellite

NASA Astrophysics Data System (ADS)

Wang, Jianrong; Wang, Renxiang; Hu, Xin; Su, Zhongbo

2017-02-01

The on-orbit calibration of geometric parameters is a key step in improving the location accuracy of satellite images without using Ground Control Points (GCPs). Most methods of on-orbit calibration are based on the self-calibration using additional parameters. When using additional parameters, different number of additional parameters may lead to different results. The triangulation bundle adjustment is another way to calibrate the geometric parameters of camera, which can describe the changes in each geometric parameter. When triangulation bundle adjustment method is applied to calibrate geometric parameters, a prerequisite is that the strip model can avoid systematic deformation caused by the rate of attitude changes. Concerning the stereo camera, the influence of the intersection angle should be considered during calibration. The Equivalent Frame Photo (EFP) bundle adjustment based on the Line-Matrix CCD (LMCCD) image can solve the systematic distortion of the strip model, and obtain high accuracy location without using GCPs. In this paper, the triangulation bundle adjustment is used to calibrate the geometric parameters of TH-1 satellite cameras based on LMCCD image. During the bundle adjustment, the three-line array cameras are reconstructed by adopting the principle of inverse triangulation. Finally, the geometric accuracy is validated before and after on-orbit calibration using 5 testing fields. After on-orbit calibration, the 3D geometric accuracy is improved to 11.8 m from 170 m. The results show that the location accuracy of TH-1 without using GCPs is significantly improved using the on-orbit calibration of the geometric parameters.

Small-angle X-ray scattering and rheological characterization of alginate gels. 2. Time-resolved studies on ionotropic gels

NASA Astrophysics Data System (ADS)

Yuguchi, Y.; Urakawa, H.; Kajiwara, K.; Draget, K. I.; Stokke, B. T.

2000-10-01

Gelation was observed by time-resolved small-angle X-ray scattering and rheology on 10 mg/ml Ca-alginate gels prepared by in situ release of Ca 2+ from CaEGTA or CaCO 3 with total Ca 2+ concentration in the range 10-20 mM. This was carried out for alginates having a fraction of α- L-GulA (G) of FG=0.39 and 0.68, respectively, obtained by the selection of alginates isolated from two different brown algae, Ascophyllum nodosum and Laminaria hyperborea stipe. Correlation between the rheological data and SAXS data shows that a large fraction of the lateral association precedes the formation of a continuous network through the sample cell. Following the initial association of chain segments in junction zones, the analysis using two-component broken rod model indicates the formation of larger bundles, and that the relative weight of these bundles increases with increasing time. The molecular model for the bundles is proposed by associating 2-16 units (G-blocks) composed of 14 (1→4) linked residues of α- L-GulA in parallel according to the available crystallographic data. The storage modulus increases as the bundles composed of associated alginate chains grow during the gel formation. The gel elasticity is mainly sustained by single chains in the alginate sample with a low fraction of α- L-GulA. The alginates with a high fraction of α- L-GulA associate into thicker bundles which join to form a network. Here the gel elasticity seems to be due to the flexible joints between bundles, since the fraction of single chains is extremely low.

Second Harmonic Generation Imaging Analysis of Collagen Arrangement in Human Cornea.

PubMed

Park, Choul Yong; Lee, Jimmy K; Chuck, Roy S

2015-08-01

To describe the horizontal arrangement of human corneal collagen bundles by using second harmonic generation (SHG) imaging. Human corneas were imaged with an inverted two photon excitation fluorescence microscope. The excitation laser (Ti:Sapphire) was tuned to 850 nm. Backscatter signals of SHG were collected through a 425/30-nm bandpass emission filter. Multiple, consecutive, and overlapping image stacks (z-stacks) were acquired to generate three dimensional data sets. ImageJ software was used to analyze the arrangement pattern (irregularity) of collagen bundles at each image plane. Collagen bundles in the corneal lamellae demonstrated a complex layout merging and splitting within a single lamellar plane. The patterns were significantly different in the superficial and limbal cornea when compared with deep and central regions. Collagen bundles were smaller in the superficial layer and larger in deep lamellae. By using SHG imaging, the horizontal arrangement of corneal collagen bundles was elucidated at different depths and focal regions of the human cornea.

Effectiveness of a Model Bundle Payment Initiative for Femur Fracture Patients.

PubMed

Lott, Ariana; Belayneh, Rebekah; Haglin, Jack; Konda, Sanjit; Egol, Kenneth A

2018-05-28

Analyze the effectiveness of a BPCI (Bundle Payments for Care Improvement) initiative for patients who would be included in a future potential Surgical Hip and Femur Fracture Treatment (SHFFT) bundle. Retrospective cohort SETTING:: Single Academic Institution PATIENTS/PARTICIPANTS:: Patients discharged with operative fixation of a hip or femur fracture (DRG codes 480-482) between 1/2015-10/2016 were included. A BPCI initiative based upon an established program for BPCI Total Joint Arthroplasty (TJA) was initiated for patients with hip and femur fractures in January 2016. Patients were divided into non-bundle (care before initiative) and bundle (care with initiative) cohorts. Application of BPCI principles MAIN OUTCOME MEASURES:: Length of stay, location of discharge, readmissions RESULTS:: 116 patients participated in the "institutional bundle," and 126 received care prior to the initiative. There was a trend towards decreased mean length of stay, (7.3 ± 6.3 days vs. 6.8 ± 4.0 days, p=0.457) and decreased readmission within 90 days (22.2% vs. 18.1%, p=0.426). The number of patients discharged home doubled (30.2% vs. 14.3%, p=0.008). There was no difference in readmission rates in bundle vs. non-bundle patients based on discharged home status; however, bundle patients discharged to SNF trended towards less readmissions than non-bundle patients discharged to SNF (37.3% vs. 50.6%, p=0.402). Mean episode cost reduction due to initiative was estimated to be $6,450 using Medicare reimbursement data. This study demonstrates the potential success of a BPCI initiative at one institution in decreasing post-acute care facility utilization and cost of care when used for a hip and femur fracture population. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The Effect of Remnant Tissue Preservation in Anatomic Double-Bundle ACL Reconstruction on Knee Stability and Graft Maturation.

PubMed

Takahashi, Tsuneari; Kimura, Masashi; Hagiwara, Keiichi; Ohsawa, Takashi; Takeshita, Katsushi

2018-06-13

Several investigators have developed anterior cruciate ligament reconstructions (ACLR) with remnant tissue preservation (RTP) and have reported better clinical outcomes. However, the effects of RTP remain controversial. To date, no reports have compared both clinical and radiological outcomes of anatomic double-bundle ACLR using the hamstring tendon and outside-in technique with/without RTP. This article evaluates the effectiveness of RTP in ACLR on knee stability and graft maturation. In total, 75 patients with unilateral ACL injury who had undergone anatomic double-bundle ACLR using autografted hamstring tendon either with RTP (Group P, n  = 43) or without (Group N, n  = 32) were enrolled. Clinical scores, pre- and postoperative side-to-side differences (SSDs) obtained using Telos, radiological evaluations of the grafted tendon using the signal/noise quotient (SNQ) measured using magnetic resonance imaging, and arthroscopic evaluations of the grafted tendon were retrospectively compared between the groups. Postoperative SSDs were smaller in the Group P (0.78 ± 1.90 mm) than in the Group N (1.29 ± 2.18 mm); however, this difference was not significant. Comparing two subgroups of the Group P, the SSD was significantly smaller in those with sufficient remnant coverage (-0.56 ± 1.38 mm) than in those without (1.48 ± 1.77 mm) ( p  = 0.019), as well as in the Group N patients ( p  = 0.019). The degree of synovial coverage of the anteromedial ( p  = 0.0064) and posterolateral ( p  = 0.032) bundle grafted tendon at the time of second-look arthroscopy was significantly better in the Group P than in the Group N. SNQ values of ACL grafted tendon at proximal ( p  = 0.049), middle, and distal ( p  = 0.039) one-third in Group P were better than those in Group N. RTP may enhance synovial coverage and maturation of the grafted tendon. Sufficient remnant tissue coverage may contribute to better knee stability. This is a Level III, retrospective comparative study. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Magnetic Propulsion of Microswimmers with DNA-Based Flagellar Bundles.

PubMed

Maier, Alexander M; Weig, Cornelius; Oswald, Peter; Frey, Erwin; Fischer, Peer; Liedl, Tim

2016-02-10

We show that DNA-based self-assembly can serve as a general and flexible tool to construct artificial flagella of several micrometers in length and only tens of nanometers in diameter. By attaching the DNA flagella to biocompatible magnetic microparticles, we provide a proof of concept demonstration of hybrid structures that, when rotated in an external magnetic field, propel by means of a flagellar bundle, similar to self-propelling peritrichous bacteria. Our theoretical analysis predicts that flagellar bundles that possess a length-dependent bending stiffness should exhibit a superior swimming speed compared to swimmers with a single appendage. The DNA self-assembly method permits the realization of these improved flagellar bundles in good agreement with our quantitative model. DNA flagella with well-controlled shape could fundamentally increase the functionality of fully biocompatible nanorobots and extend the scope and complexity of active materials.

From Biological Cilia to Artificial Flow Sensors: Biomimetic Soft Polymer Nanosensors with High Sensing Performance

NASA Astrophysics Data System (ADS)

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Karavitaki, K. Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P.; Triantafyllou, Michael

2016-09-01

We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Rheology and nanoindentation experiments are used to ensure that the viscous properties of the hyaluronic acid (HA)-based hydrogel are close to the biological cupula. A dome-shaped HA hydrogel cupula that encapsulates the artificial hair cell bundle is formed through precision drop-casting and swelling processes. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. Functioning with principles analogous to the hair bundles, the sensors achieve a sensitivity and threshold detection limit of 300 mV/(m/s) and 8 μm/s, respectively. These self-powered, sensitive, flexible, biocompatibale and miniaturized sensors can find extensive applications in navigation and maneuvering of underwater robots, artificial hearing systems, biomedical and microfluidic devices.

From Biological Cilia to Artificial Flow Sensors: Biomimetic Soft Polymer Nanosensors with High Sensing Performance.

PubMed

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Karavitaki, K Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P; Triantafyllou, Michael

2016-09-13

We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Rheology and nanoindentation experiments are used to ensure that the viscous properties of the hyaluronic acid (HA)-based hydrogel are close to the biological cupula. A dome-shaped HA hydrogel cupula that encapsulates the artificial hair cell bundle is formed through precision drop-casting and swelling processes. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. Functioning with principles analogous to the hair bundles, the sensors achieve a sensitivity and threshold detection limit of 300 mV/(m/s) and 8 μm/s, respectively. These self-powered, sensitive, flexible, biocompatibale and miniaturized sensors can find extensive applications in navigation and maneuvering of underwater robots, artificial hearing systems, biomedical and microfluidic devices.

Increased Compliance With Supervised Rehabilitation Improves Functional Outcome and Return to Sport After Anterior Cruciate Ligament Reconstruction in Recreational Athletes

PubMed Central

Han, Fucai; Banerjee, Anirban; Shen, Liang; Krishna, Lingaraj

2015-01-01

Background: Successful return to sport is an important outcome measure after anterior cruciate ligament (ACL) reconstruction and a reason for patients’ decisions to elect surgery. Rehabilitation programs supervised by physical therapists are routinely prescribed after ACL reconstruction surgery. However, the added advantage of supervised physical therapy after ACL reconstruction is still debatable. Hypothesis: Attending more supervised physical therapy sessions after arthroscopic ACL reconstruction in recreational athletes increases their chance of successful return to sport. Study Design: Cohort study; Level of evidence, 3. Methods: The authors analyzed 93 recreational athletes who underwent arthroscopic ACL reconstruction. After arthroscopic single-bundle ACL reconstruction, patients were advised to attend 20 supervised physical therapy sessions. Patients’ demographics, surgical details, and outcome measures (Knee injury and Osteoarthritis Outcome Score [KOOS], Lysholm scale, and Short Form–36 Health Survey [SF-36]) were recorded presurgery and at 1-year follow-up. Ability to return to sports was documented through patients’ self-report. The attendance at physical therapy by each patient was obtained by examining database records and assessed as fully compliant (>15 sessions), moderately compliant (6-15 sessions), or noncompliant (<6 sessions). Results: Patients in the fully compliant group had significantly greater odds (odds ratio [OR], 18.5; 95% CI, 1.9-184.5; P = .013) of a successful return to sport as compared with the noncompliant group. Patients in the moderately compliant group also had greater odds of returning to sport as compared with the noncompliant group (OR, 4.2; 95% CI, 1.0-16.6; P = .043). Patients in the fully compliant group had significantly greater scores on the Lysholm (P < .001), KOOS Sports and Recreation subscale (P = .021), KOOS Symptoms subscale (P = .040), and SF-36 physical component summary (PCS) (P = .012) as compared with the noncompliant group. Moderately compliant patients had significantly greater scores on the Lysholm (P = .004), KOOS Sports and Recreation (P = .026), KOOS Symptoms (P = .041), KOOS Quality of Life (P = .022), and SF-36 PCS (P = .004) as compared with noncompliant patients. Conclusion: In recreational athletes, moderate to full compliance with a supervised physical therapy program predicts improved knee function and a greater chance of returning to sport 1 year after ACL reconstruction. PMID:26740958

Optical design of endoscopic shape-tracker using quantum dots embedded in fiber bundles

NASA Astrophysics Data System (ADS)

Eisenstein, Jessica; Gavalis, Robb; Wong, Peter Y.; Cao, Caroline G. L.

2009-08-01

Colonoscopy is the current gold standard for colon cancer screening and diagnosis. However, the near-blind navigation process employed during colonoscopy results in endoscopist disorientation and scope looping, leading to missed detection of tumors, incorrect localization, and pain for the patient. A fiber optic bend sensor, which would fit into the working channel of a colonoscope, is developed to aid navigation through the colon during colonoscopy. The bend sensor is comprised of a bundle of seven fibers doped with quantum dots (QDs). Each fiber within the bundle contains a unique region made up of three zones with differently-colored QDs, spaced 120° apart circumferentially on the fiber. During bending at the QD region, light lost from the fiber's core is coupled into one of the QD zones, inducing fluorescence of the corresponding color whose intensity is proportional to the degree of bending. A complementary metal oxide semiconductor camera is used to obtain an image of the fluorescing end faces of the fiber bundle. The location of the fiber within the bundle, the color of fluorescence, and the fluorescence intensity are used to determine the bundle's bending location, direction, and degree of curvature, respectively. Preliminary results obtained using a single fiber with three QD zones and a seven-fiber bundle containing one active fiber with two QDs (180° apart) demonstrate the feasibility of the concept. Further developments on fiber orientation during bundling and the design of a graphical user interface to communicate bending information are also discussed.

Transduction channels' gating can control friction on vibrating hair-cell bundles in the ear.

PubMed

Bormuth, Volker; Barral, Jérémie; Joanny, Jean-François; Jülicher, Frank; Martin, Pascal

2014-05-20

Hearing starts when sound-evoked mechanical vibrations of the hair-cell bundle activate mechanosensitive ion channels, giving birth to an electrical signal. As for any mechanical system, friction impedes movements of the hair bundle and thus constrains the sensitivity and frequency selectivity of auditory transduction. Friction is generally thought to result mainly from viscous drag by the surrounding fluid. We demonstrate here that the opening and closing of the transduction channels produce internal frictional forces that can dominate viscous drag on the micrometer-sized hair bundle. We characterized friction by analyzing hysteresis in the force-displacement relation of single hair-cell bundles in response to periodic triangular stimuli. For bundle velocities high enough to outrun adaptation, we found that frictional forces were maximal within the narrow region of deflections that elicited significant channel gating, plummeted upon application of a channel blocker, and displayed a sublinear growth for increasing bundle velocity. At low velocity, the slope of the relation between the frictional force and velocity was nearly fivefold larger than the hydrodynamic friction coefficient that was measured when the transduction machinery was decoupled from bundle motion by severing tip links. A theoretical analysis reveals that channel friction arises from coupling the dynamics of the conformational change associated with channel gating to tip-link tension. Varying channel properties affects friction, with faster channels producing smaller friction. We propose that this intrinsic source of friction may contribute to the process that sets the hair cell's characteristic frequency of responsiveness.

Transduction channels’ gating can control friction on vibrating hair-cell bundles in the ear

PubMed Central

Bormuth, Volker; Barral, Jérémie; Joanny, Jean-François; Jülicher, Frank; Martin, Pascal

2014-01-01

Hearing starts when sound-evoked mechanical vibrations of the hair-cell bundle activate mechanosensitive ion channels, giving birth to an electrical signal. As for any mechanical system, friction impedes movements of the hair bundle and thus constrains the sensitivity and frequency selectivity of auditory transduction. Friction is generally thought to result mainly from viscous drag by the surrounding fluid. We demonstrate here that the opening and closing of the transduction channels produce internal frictional forces that can dominate viscous drag on the micrometer-sized hair bundle. We characterized friction by analyzing hysteresis in the force–displacement relation of single hair-cell bundles in response to periodic triangular stimuli. For bundle velocities high enough to outrun adaptation, we found that frictional forces were maximal within the narrow region of deflections that elicited significant channel gating, plummeted upon application of a channel blocker, and displayed a sublinear growth for increasing bundle velocity. At low velocity, the slope of the relation between the frictional force and velocity was nearly fivefold larger than the hydrodynamic friction coefficient that was measured when the transduction machinery was decoupled from bundle motion by severing tip links. A theoretical analysis reveals that channel friction arises from coupling the dynamics of the conformational change associated with channel gating to tip-link tension. Varying channel properties affects friction, with faster channels producing smaller friction. We propose that this intrinsic source of friction may contribute to the process that sets the hair cell’s characteristic frequency of responsiveness. PMID:24799674

Younger Patients and Men Achieve Higher Outcome Scores Than Older Patients and Women After Anterior Cruciate Ligament Reconstruction.

PubMed

Webster, Kate E; Feller, Julian A

2017-10-01

There is some evidence that functional performance and validated outcome scores differ according to the gender, age, and sport participation status of a patient after anterior cruciate ligament (ACL) reconstruction. However, the impact of these three factors, and interaction among them, has not been studied across a large relatively homogeneous group of patients to better elucidate their impact. We reviewed a large cohort of patients who had undergone ACL reconstruction to determine if ROM, knee laxity, objective performance measures, and validated outcome scores differed according to (1) gender; (2) age; and (3) sport participation status. This was a retrospective analysis of prospectively collected data. Between 2007 and 2016, we performed 3452 single-bundle ACL reconstructions in patients who participated in sport before ACL injury. Of those, complete followup (including preoperative scores and scores at 1 year after surgery; mean, 14 months; range, 12-20 months) was available on 2672 (77%) of patients. Those lost to followup and those accounted for were not different in terms of age, gender, and sports participation at baseline. The study group consisted of 1726 (65%) men and 946 (35%) women with a mean ± SD age of 28 ± 10 years. For these patients, the following measures were obtained: knee ROM (flexion and extension deficit), instrumented knee laxity, single and triple hop for distance limb symmetry index (LSI), International Knee Documentation Committee (IKDC) subjective evaluation, and Single Assessment Numeric Evaluation score. Mean scores and measures of variability were calculated for each outcome measure. Comparisons were made among gender, age, and sport status. Men had less knee laxity after reconstruction (men 1.1 ± 2.2 mm, women 1.3 ± 2.4 mm; mean difference 0.2 mm [0.1-0.4], p < 0.001), greater limb symmetry (single limb hop men: 94% ± 12%, women 91% ± 13%, mean difference 3% [2%-4%], p < 0.001), and higher IKDC scores than did women (men 84 ± 12, women 82 ± 12, mean difference 2 [1-3], p < 0.001). With the exception of instrumented laxity, all outcome measures showed reduced deficits and higher scores in younger patients. This was most marked for LSI scores between the youngest and oldest aged patient groups (crossover hop: < 16 years 99% ± 10%, > 45 years 90% ± 16%, mean difference: 9 [5-11], p < 0.001). Patients who had returned to their preinjury sport also scored higher and had smaller deficits for all outcomes except ROM compared with patients who had not returned to sport at the time of followup (IKDC subjective: returned 90 ± 9, no sport 79 ± 12, mean difference 11 points [9-12], p < 0.001; single limb hop: returned 97 ± 10, no sport 91 ± 14, mean difference 6% [5%-7%], p < 0.001). This study showed that some of the most commonly used functional performance and validated clinical scores for ACL reconstruction are superior for patients who are younger, male, and have returned to preinjury sport. Reference to these data allows clinicians to more effectively evaluate a patient based on their age, gender, and sport status when making return to sport and rehabilitation decisions. Level III, therapeutic study.

Atomic resolution Z-contrast imaging and energy loss spectroscopy of carbon nanotubes and bundles

NASA Astrophysics Data System (ADS)

Lupini, A. R.; Chisholm, M. F.; Puretzky, A. A.; Eres, G.; Melechko, A. V.; Schaaff, G.; Lowndes, D. H.; Geohegan, D. B.; Schittenhelm, H.; Pennycook, S. J.; Wang, Y.; Smalley, R. E.

2002-03-01

Single-wall carbon nanotubes and bundles were studied by a combination of techniques, including conventional imaging and diffraction, atomic resolution Z-contrast imaging in an aberration corrected STEM and electron energy loss spectroscopy (EELS). EELS is ideally suited for the analysis of carbon based structures because of the ability to distinguish between the different forms, specifically nanotubes, graphite, amorphous carbon and diamond. Numerous attempts were made to synthesize crystals of single walled carbon nanotubes, using both solution and vapor deposition of precursor structures directly onto TEM grids for in-situ annealing. The range of structures produced will be discussed.

Does the tibial remnant of the anterior cruciate ligament promote ligamentization?

PubMed

Lee, Byung Ill; Kim, Byoung Min; Kho, Duk Hwan; Kwon, Sai Won; Kim, Hyeung June; Hwang, Hyun Ryong

2016-12-01

The purpose of this study was to clarify the difference in ligamentization between the remnant-preserving (RP) and remnant-sacrificing (RS) techniques in anterior cruciate ligament (ACL) reconstruction using magnetic resonance imaging (MRI). A retrospective comparative study was carried out on 98 patients undergoing ACL reconstruction using either an RP (n=56) or RS (n=42) technique. MRI was performed at one of four time points postoperatively, and the signal intensity of the ACL graft was analyzed using the signal to noise quotient (SNQ) ratio and inter-bundle high signal intensity, along with an analysis of the survival rate of remnant tissue. The mean SNQ ratio of grafted tendons in the RP group was significantly higher than that seen in the RS group in the proximal and middle regions two to four months after surgery (P<0.05) and was significantly lower than that seen in the RS group in all regions at 12 -18months (P<0.05). The inter-bundle high signal intensity was observed more frequently in the RP group (73.7%) at two to four months. Tibial remnants were observed on postoperative MRI regardless of when MRI was conducted. The ACL graft of the RP group showed higher signal intensity in the early stage and lower signal intensity in the late stage compared to that of the RS group. The ligamentization of grafts in the RP group proceeded more quickly. Preserving the remnant in ACL reconstruction appears to have a positive effect on ligamentization. Copyright © 2016 Elsevier B.V. All rights reserved.

PASSIVE MECHANICAL PROPERTIES AND RELATED PROTEINS CHANGE WITH BOTULINUM NEUROTOXIN A INJECTION OF NORMAL SKELETAL MUSCLE

PubMed Central

Thacker, Bryan E.; Tomiya, Akihito; Hulst, Jonah B.; Suzuki, Kentaro P.; Bremner, Shannon N.; Gastwirt, Randy F.; Greaser, Marion L.; Lieber, Richard L.; Ward, Samuel R.

2011-01-01

Summary The effects of botulinum neurotoxin A on the passive mechanical properties of skeletal muscle have not been investigated, but may have significant impact in the treatment of neuromuscular disorders including spasticity. Single fiber and fiber bundle passive mechanical testing was performed on rat muscles treated with botulinum neurotoxin A. Myosin heavy chain and titin composition of single fibers was determined by gel electrophoresis. Muscle collagen content was determined using a hydroxyproline assay. Neurotoxin-treated single fiber passive elastic modulus was reduced compared to control fibers (53.00 kPa versus 63.43 kPa). Fiber stiffness and slack sarcomere length were also reduced compared to control fibers and myosin heavy chain composition shifted from faster to slower isoforms. Average titin molecular weight increased 1.77% after treatment. Fiber bundle passive elastic modulus increased following treatment (168.83 kPa versus 75.14 kPa). Bundle stiffness also increased while collagen content per mass of muscle tissue increased 38%. Injection of botulinum neurotoxin A produces an effect on the passive mechanical properties of normal muscle that is opposite to the changes observed in spastic muscles. PMID:21853457

Passive mechanical properties and related proteins change with botulinum neurotoxin A injection of normal skeletal muscle.

PubMed

Thacker, Bryan E; Tomiya, Akihito; Hulst, Jonah B; Suzuki, Kentaro P; Bremner, Shannon N; Gastwirt, Randy F; Greaser, Marion L; Lieber, Richard L; Ward, Samuel R

2012-03-01

The effects of botulinum neurotoxin A on the passive mechanical properties of skeletal muscle have not been investigated, but may have significant impact in the treatment of neuromuscular disorders including spasticity. Single fiber and fiber bundle passive mechanical testing was performed on rat muscles treated with botulinum neurotoxin A. Myosin heavy chain and titin composition of single fibers was determined by gel electrophoresis. Muscle collagen content was determined using a hydroxyproline assay. Neurotoxin-treated single fiber passive elastic modulus was reduced compared to control fibers (53.00 kPa vs. 63.43 kPa). Fiber stiffness and slack sarcomere length were also reduced compared to control fibers and myosin heavy chain composition shifted from faster to slower isoforms. Average titin molecular weight increased 1.77% after treatment. Fiber bundle passive elastic modulus increased following treatment (168.83  kPa vs. 75.14 kPa). Bundle stiffness also increased while collagen content per mass of muscle tissue increased 38%. Injection of botulinum neurotoxin A produces an effect on the passive mechanical properties of normal muscle that is opposite to the changes observed in spastic muscles. Copyright © 2011 Orthopaedic Research Society.

Selective Oxidation of Amorphous Carbon Layers without Damaging Embedded Single Wall Carbon Nanotube Bundles

NASA Astrophysics Data System (ADS)

Choi, Young Chul; Lim, Seong Chu

2013-11-01

Single wall carbon nanotubes (SWCNTs) were synthesized by arc discharge, and then purified by selective oxidation of amorphous carbon layers that were found to encase SWCNT bundles and catalyst metal particles. In order to remove selectively the amorphous carbon layers with SWCNTs being intact, we have systematically investigated the thermal treatment conditions; firstly, setting the temperature by measuring the activation energies of SWCNTs and amorphous carbon layers, and then, secondly, finding the optimal process time. As a consequence, the optimal temperature and time for the thermal treatment was found to be 460 °C and 20 min, respectively. The complete elimination of surrounding amorphous carbon layers makes it possible to efficiently disperse the SWCNT bundles, resulting in high absorbance of SWCNT-ink. The SWCNTs which were thermal-treated at optimized temperature (460 °C) and duration (20 min) showed much better crystallinity, dispersibility, and transparent conducting properties, compared with as-synthesized and the nanotubes thermal-treated at different experimental conditions.

Development of the nervous system in Phoronopsis harmeri (Lophotrochozoa, Phoronida) reveals both deuterostome- and trochozoan-like features

PubMed Central

2012-01-01

Background Inferences concerning the evolution of invertebrate nervous systems are often hampered by the lack of a solid data base for little known but phylogenetically crucial taxa. In order to contribute to the discussion concerning the ancestral neural pattern of the Lophotrochozoa (a major clade that includes a number of phyla that exhibit a ciliated larva in their life cycle), we investigated neurogenesis in Phoronopsis harmeri, a member of the poorly studied Phoronida, by using antibody staining against serotonin and FMRFamide in combination with confocal microscopy and 3D reconstruction software. Results The larva of Phoronopsis harmeri exhibits a highly complex nervous system, including an apical organ that consists of four different neural cell types, such as numerous serotonin-like immunoreactive flask-shaped cells. In addition, serotonin- and FMRFamide-like immunoreactive bi- or multipolar perikarya that give rise to a tentacular neurite bundle which innervates the postoral ciliated band are found. The preoral ciliated band is innervated by marginal serotonin-like as well as FMRFamide-like immunoreactive neurite bundles. The telotroch is innervated by two neurite bundles. The oral field is the most densely innervated area and contains ventral and ventro-lateral neurite bundles as well as several groups of perikarya. The digestive system is innervated by both serotonin- and FMRFamide-like immunoreactive neurites and perikarya. Importantly, older larvae of P. harmeri show a paired ventral neurite bundle with serial commissures and perikarya. Conclusions Serotonin-like flask-shaped cells such as the ones described herein for Phoronopsis harmeri are found in the majority of lophotrochozoan larvae and therefore most likely belong to the ground pattern of the last common lophotrochozoan ancestor. The finding of a transitory paired ventral neurite bundle with serially repeated commissures that disappears during metamorphosis suggests that such a structure was part of the “ur-phoronid” nervous system, but was lost in the adult stage, probably due to its acquired sessile benthic lifestyle. PMID:22827441

Image Processing for Cameras with Fiber Bundle Image Relay

DTIC Science & Technology

length. Optical fiber bundles have been used to couple between this focal surface and planar image sensors . However, such fiber-coupled imaging systems...coupled to six discrete CMOS focal planes. We characterize the locally space-variant system impulse response at various stages: monocentric lens image...vignetting, and stitch together the image data from discrete sensors into a single panorama. We compare processed images from the prototype to those taken with

A 90-day Bundled Payment for Primary Single-level Lumbar Discectomy/Decompression: What Does "Big Data" Say?

PubMed

Jain, Nikhil; Virk, Sohrab S; Phillips, Frank M; Yu, Elizabeth; Khan, Safdar N

2018-04-01

Episode-based bundling may become the major form of reimbursement for many elective spine procedures. As the amount for a 90-day episode of care is not known for a lumbar discectomy, we analyzed the previous reimbursements from Commercial payers (2007-Q2 2015), Medicare Advantage (2007-Q2 2015), and Medicare (2005-2012) for a primary single-level lumbar discectomy/decompression. Distribution of payments among various service providers was studied and a 90-day bundle was simulated. Depending on the payer type, the average facility costs constituted 59.7% to 73.6% of total payments, followed by surgeon's fees, which accounted for 13.7% to 18.5%. Postacute services made up 8.8% to 15.8% of the total reimbursement. Surgeries performed in the inpatient setting were significantly more expensive as compared with surgeries performed in the outpatient setting (P<0.01). The average 90-day bundle amount was estimated at $11,091, $6571, and $6239 for Commercial payers, Medicare Advantage, and Medicare, respectively. Overall, service providers in the Southern region were reimbursed the lowest from Commercial payers and Medicare, compared with other regions. Postacute services are not as major cost drivers after discectomy as after total joint arthroplasty or hip fracture repair.

The Orientation and Variation of the Acromioclavicular Ligament: An Anatomic Study.

PubMed

Nakazawa, Masataka; Nimura, Akimoto; Mochizuki, Tomoyuki; Koizumi, Masahiro; Sato, Tatsuo; Akita, Keiichi

2016-10-01

Several biomechanical studies have shown that the acromioclavicular (AC) ligament prevents posterior translation of the clavicle in the horizontal plane. In anatomy textbooks, however, the AC ligament is illustrated as running straight across the AC joint surface. The AC ligament does not run straight across the joint surface, and the configuration of the AC ligament may vary. Descriptive laboratory study. We used 16 pairs of shoulder girdles in this study. After identifying the AC ligament, we macroscopically investigated the orientation and attachment of the ligament and measured the angle between the ligament and the line perpendicular to the AC joint surface by using a digital goniometer. In addition, the AC joint inclination angle was measured, and the Spearman rank correlation coefficient between the joint inclination and the ligament angle was calculated. Finally, we sought to classify the AC ligament based on its configuration. Of the 16 pairs of specimens, 3 pairs of shoulders were histologically examined. The AC ligament was divided into 2 parts: a bundle at the superoposterior (SP) part and a bundle at the anteroinferior (AI) part of the joint. The well-developed SP bundle was consistent and ran obliquely at an average ± SD 30° ± 6° in relation to the AC joint surface, from the anterior part of the acromion to the posterior part of the distal clavicle. The joint inclination was 70° ± 12°, and a negative moderate correlation was found between the joint inclination and the ligament angle (P = .02, r = -0.46). In comparison, the AI bundle was thin and narrow, and it could be categorized into 3 types according to its various configurations. The AC ligament could be separated into the SP bundle and the AI bundle. The SP bundle ran posteriorly toward the distal clavicle from the acromion at an average angle of 30° to the joint surface. Anatomic reconstruction, based on the current findings in combination with findings regarding the coracoclavicular ligament, could facilitate improved outcome in the treatment of AC joint disruption. © 2016 The Author(s).

Bundling of elastic filaments induced by hydrodynamic interactions

NASA Astrophysics Data System (ADS)

Man, Yi; Page, William; Poole, Robert J.; Lauga, Eric

2017-12-01

Peritrichous bacteria swim in viscous fluids by rotating multiple helical flagellar filaments. As the bacterium swims forward, all its flagella rotate in synchrony behind the cell in a tight helical bundle. When the bacterium changes its direction, the flagellar filaments unbundle and randomly reorient the cell for a short period of time before returning to their bundled state and resuming swimming. This rapid bundling and unbundling is, at its heart, a mechanical process whereby hydrodynamic interactions balance with elasticity to determine the time-varying deformation of the filaments. Inspired by this biophysical problem, we present in this paper what is perhaps the simplest model of bundling whereby two or more straight elastic filaments immersed in a viscous fluid rotate about their centerline, inducing rotational flows which tend to bend the filaments around each other. We derive an integrodifferential equation governing the shape of the filaments resulting from mechanical balance in a viscous fluid at low Reynolds number. We show that such equation may be evaluated asymptotically analytically in the long-wavelength limit, leading to a local partial differential equation governed by a single dimensionless bundling number. A numerical study of the dynamics predicted by the model reveals the presence of two configuration instabilities with increasing bundling numbers: first to a crossing state where filaments touch at one point and then to a bundled state where filaments wrap along each other in a helical fashion. We also consider the case of multiple filaments and the unbundling dynamics. We next provide an intuitive physical model for the crossing instability and show that it may be used to predict analytically its threshold and adapted to address the transition to a bundling state. We then use a macroscale experimental implementation of the two-filament configuration in order to validate our theoretical predictions and obtain excellent agreement. This long-wavelength model of bundling will be applicable to other problems in biological physics and provides the groundwork for further, more realistic, models of flagellar bundling.

Advanced synchronous luminescence imaging for chemical and medical diagnostics

DOEpatents

Vo-Dinh, Tuan

2006-09-05

A diagnostic method and associated system includes the steps of exposing at least one sample location with excitation radiation through a single optical waveguide or a single optical waveguide bundle, wherein the sample emits emission radiation in response to the excitation radiation. The same single optical waveguide or the single optical waveguide bundle receives at least a portion of the emission radiation from the sample, thus providing co-registration of the excitation radiation and the emission radiation. The wavelength of the excitation radiation and emission radiation is synchronously scanned to produce a spectrum upon which an image can be formed. An increased emission signal is generated by the enhanced overlap of the excitation and emission focal volumes provided by co-registration of the excitation and emission signals thus increasing the sensitivity as well as decreasing the exposure time necessary to obtain an image.

Development and characterization of a handheld hyperspectral Raman imaging probe system for molecular characterization of tissue on mesoscopic scales.

PubMed

St-Arnaud, Karl; Aubertin, Kelly; Strupler, Mathias; Madore, Wendy-Julie; Grosset, Andrée-Anne; Petrecca, Kevin; Trudel, Dominique; Leblond, Frédéric

2018-01-01

Raman spectroscopy is a promising cancer detection technique for surgical guidance applications. It can provide quantitative information relating to global tissue properties associated with structural, metabolic, immunological, and genetic biochemical phenomena in terms of molecular species including amino acids, lipids, proteins, and nucleic acid (DNA). To date in vivo Raman spectroscopy systems mostly included probes and biopsy needles typically limited to single-point tissue interrogation over a scale between 100 and 500 microns. The development of wider field handheld systems could improve tumor localization for a range of open surgery applications including brain, ovarian, and skin cancers. Here we present a novel Raman spectroscopy implementation using a coherent imaging bundle of fibers to create a probe capable of reconstructing molecular images over mesoscopic fields of view. Detection is performed using linear scanning with a rotation mirror and an imaging spectrometer. Different slits widths were tested at the entrance of the spectrometer to optimize spatial and spectral resolution while preserving sufficient signal-to-noise ratios to detect the principal Raman tissue features. The nonbiological samples, calcite and polytetrafluoroethylene (PTFE), were used to characterize the performance of the system. The new wide-field probe was tested on ex vivo samples of calf brain and swine tissue. Raman spectral content of both tissue types were validated with data from the literature and compared with data acquired with a single-point Raman spectroscopy probe. The single-point probe was used as the gold standard against which the new instrument was benchmarked as it has already been thoroughly validated for biological tissue characterization. We have developed and characterized a practical noncontact handheld Raman imager providing tissue information at a spatial resolution of 115 microns over a field of view >14 mm 2 and a spectral resolution of 6 cm -1 over the whole fingerprint region. Typical integration time to acquire an entire Raman image over swine tissue was set to approximately 100 s. Spectra acquired with both probes (single-point and wide-field) showed good agreement, with a Pearson correlation factor >0.85 over different tissue categories. Protein and lipid content of imaged tissue were manifested into the measured spectra which correlated well with previous findings in the literature. An example of quantitative molecular map is presented for swine tissue and calf brain based on the ratio of protein-to-lipid content showing clear delineations between white and gray matter as well as between adipose and muscle tissue. We presented the development of a Raman imaging probe with a field of view of a few millimeters and a spatial resolution consistent with standard surgical imaging methods using an imaging bundle. Spectra acquired with the newly developed system on swine tissue and calf brain correlated well with an establish single-point probe and observed spectral features agreed with previous finding in the literature. The imaging probe has demonstrated its ability to reconstruct molecular images of soft tissues. The approach presented here has a lot of potential for the development of surgical Raman imaging probe to guide the surgeon during cancer surgery. © 2017 American Association of Physicists in Medicine.

Dimerization and actin-bundling properties of villin and its role in the assembly of epithelial cell brush borders.

PubMed

George, Sudeep P; Wang, Yaohong; Mathew, Sijo; Srinivasan, Kamalakkannan; Khurana, Seema

2007-09-07

Villin is a major actin-bundling protein in the brush border of epithelial cells. In this study we demonstrate for the first time that villin can bundle actin filaments using a single F-actin binding site, because it has the ability to self-associate. Using fluorescence resonance energy transfer, we demonstrate villin self-association in living cells in microvilli and in growth factor-stimulated cells in membrane ruffles and lamellipodia. Using sucrose density gradient, size-exclusion chromatography, and matrix-assisted laser desorption ionization time-of-flight, the majority of villin was identified as a monomer or dimer. Villin dimers were also identified in Caco-2 cells, which endogenously express villin and Madin-Darby canine kidney cells that ectopically express villin. Using truncation mutants of villin, site-directed mutagenesis, and fluorescence resonance energy transfer, an amino-terminal dimerization site was identified that regulated villin self-association in parallel conformation as well as actin bundling by villin. This detailed analysis describes for the first time microvillus assembly by villin, redefines the actin-bundling function of villin, and provides a molecular mechanism for actin bundling by villin, which could have wider implications for other actin cross-linking proteins that share a villin-like headpiece domain. Our study also provides a molecular basis to separate the morphologically distinct actin-severing and actin-bundling properties of villin.

Loading Patterns of the Posterior Cruciate Ligament in the Healthy Knee: A Systematic Review

PubMed Central

List, Renate; Oberhofer, Katja; Fucentese, Sandro F.; Snedeker, Jess G.; Taylor, William R.

2016-01-01

Background The posterior cruciate ligament (PCL) is the strongest ligament of the knee, serving as one of the major passive stabilizers of the tibio-femoral joint. However, despite a number of experimental and modelling approaches to understand the kinematics and kinetics of the ligament, the normal loading conditions of the PCL and its functional bundles are still controversially discussed. Objectives This study aimed to generate science-based evidence for understanding the functional loading of the PCL, including the anterolateral and posteromedial bundles, in the healthy knee joint through systematic review and statistical analysis of the literature. Data sources MEDLINE, EMBASE and CENTRAL Eligibility criteria for selecting studies Databases were searched for articles containing any numerical strain or force data on the healthy PCL and its functional bundles. Studied activities were as follows: passive flexion, flexion under 100N and 134N posterior tibial load, walking, stair ascent and descent, body-weight squatting and forward lunge. Method Statistical analysis was performed on the reported load data, which was weighted according to the number of knees tested to extract average strain and force trends of the PCL and identify deviations from the norms. Results From the 3577 articles retrieved by the initial electronic search, only 66 met all inclusion criteria. The results obtained by aggregating data reported in the eligible studies indicate that the loading patterns of the PCL vary with activity type, knee flexion angle, but importantly also the technique used for assessment. Moreover, different fibres of the PCL exhibit different strain patterns during knee flexion, with higher strain magnitudes reported in the anterolateral bundle. While during passive flexion the posteromedial bundle is either lax or very slightly elongated, it experiences higher strain levels during forward lunge and has a synergetic relationship with the anterolateral bundle. The strain patterns obtained for virtual fibres that connect the origin and insertion of the bundles in a straight line show similar trends to those of the real bundles but with different magnitudes. Conclusion This review represents what is now the best available understanding of the biomechanics of the PCL, and may help to improve programs for injury prevention, diagnosis methods as well as reconstruction and rehabilitation techniques. PMID:27880849

Methods for implantation of micro-wire bundles and optimization of single/multiunit recordings from human mesial temporal lobe

PubMed Central

Misra, A; Burke, JF; Ramayya, A; Jacobs, J; Sperling, MR; Moxon, KA; Kahana, MJ; Evans, JJ; Sharan, AD

2014-01-01

Objective The authors report methods developed for the implantation of micro-wire bundles into mesial temporal lobe structures and subsequent single neuron recording in epileptic patients undergoing in-patient diagnostic monitoring. This is done with the intention of lowering the perceived barriers to routine single neuron recording from deep brain structures in the clinical setting. Approach Over a 15 month period, 11 patients were implanted with platinum micro-wire bundles into mesial temporal structures. Protocols were developed for A) monitoring electrode integrity through impedance testing, B) ensuring continuous 24-7 recording, C) localizing micro-wire position and “splay” pattern and D) monitoring grounding and referencing to maintain the quality of recordings. Main Result Five common modes of failure were identified: 1) broken micro-wires from acute tensile force, 2) broken micro-wires from cyclic fatigue at stress points, 3) poor in-vivo micro-electrode separation, 4) motion artifact and 5) deteriorating ground connection and subsequent drop in common mode noise rejection. Single neurons have been observed up to 14 days post implantation and on 40% of micro-wires. Significance Long-term success requires detailed review of each implant by both the clinical and research teams to identify failure modes, and appropriate refinement of techniques while moving forward. This approach leads to reliable unit recordings without prolonging operative times, which will help increase the availability and clinical viability of human single neuron data. PMID:24608589

Three Dimensional Visualization of Human Cardiac Conduction Tissue in Whole Heart Specimens by High-Resolution Phase-Contrast CT Imaging Using Synchrotron Radiation.

PubMed

Shinohara, Gen; Morita, Kiyozo; Hoshino, Masato; Ko, Yoshihiro; Tsukube, Takuro; Kaneko, Yukihiro; Morishita, Hiroyuki; Oshima, Yoshihiro; Matsuhisa, Hironori; Iwaki, Ryuma; Takahashi, Masashi; Matsuyama, Takaaki; Hashimoto, Kazuhiro; Yagi, Naoto

2016-11-01

The feasibility of synchrotron radiation-based phase-contrast computed tomography (PCCT) for visualization of the atrioventricular (AV) conduction axis in human whole heart specimens was tested using four postmortem structurally normal newborn hearts obtained at autopsy. A PCCT imaging system at the beamline BL20B2 in a SPring-8 synchrotron radiation facility was used. The PCCT imaging of the conduction system was performed with "virtual" slicing of the three-dimensional reconstructed images. For histological verification, specimens were cut into planes similar to the PCCT images, then cut into 5-μm serial sections and stained with Masson's trichrome. In PCCT images of all four of the whole hearts of newborns, the AV conduction axis was distinguished as a low-density structure, which was serially traceable from the compact node to the penetrating bundle within the central fibrous body, and to the branching bundle into the left and right bundle branches. This was verified by histological serial sectioning. This is the first demonstration that visualization of the AV conduction axis within human whole heart specimens is feasible with PCCT. © The Author(s) 2016.

High spatial sampling light-guide snapshot spectrometer

PubMed Central

Wang, Ye; Pawlowski, Michal E.; Tkaczyk, Tomasz S.

2017-01-01

A prototype fiber-based imaging spectrometer was developed to provide snapshot hyperspectral imaging tuned for biomedical applications. The system is designed for imaging in the visible spectral range from 400 to 700 nm for compatibility with molecular imaging applications as well as satellite and remote sensing. An 81 × 96 pixel spatial sampling density is achieved by using a custom-made fiber-optic bundle. The design considerations and fabrication aspects of the fiber bundle and imaging spectrometer are described in detail. Through the custom fiber bundle, the image of a scene of interest is collected and divided into discrete spatial groups, with spaces generated in between groups for spectral dispersion. This reorganized image is scaled down by an image taper for compatibility with following optical elements, dispersed by a prism, and is finally acquired by a CCD camera. To obtain an (x, y, λ) datacube from the snapshot measurement, a spectral calibration algorithm is executed for reconstruction of the spatial–spectral signatures of the observed scene. System characterization of throughput, resolution, and crosstalk was performed. Preliminary results illustrating changes in oxygen-saturation in an occluded human finger are presented to demonstrate the system’s capabilities. PMID:29238115

In situ Raman study on single- and double-walled carbon nanotubes as a function of lithium insertion.

PubMed

Kim, Yoong Ahm; Kojima, Masahito; Muramatsu, Hiroyuki; Umemoto, Souichiro; Watanabe, Takaaki; Yoshida, Kazuto; Sato, Keigo; Ikeda, Takuya; Hayashi, Takuya; Endo, Morinobu; Terrones, Mauricio; Dresselhaus, Mildred S

2006-05-01

We investigated the electrochemical lithium ion (Li(+)) insertion/desertion behavior on highly pure and bundled single- and double-walled carbon nanotubes (SWNTs and DWNTs) using an in situ Raman technique. In general, two storage sites could host Li(+) in SWNT and DWNT bundles when varying an external potential: a) the outer surface sites, and b) the interstitial spaces within the bundles. The most sensitive changes in the tangential mode (TM) of the Raman spectra upon doping with Li(+) can be divided into two regions. The first region was found from 2.8 to 1.0 V (the coverage of Li(+) on the outer surface of a bundled nanotube) and was characterized by the loss of resonant conditions via partial charge transfer, where the G(+) line of the SWNT and the TM of the outer tube of DWNTs experienced a highly depressed intensity, but remained almost constant in frequency. The appearance of a Breit-Wigner-Fano (BWF) profile provided strong evidence of metallic inner tubes within DWNTs. The second region was observed when the applied potentials ranged from 0.9 to 0 V and was characterized by Li(+) diffusion into the interstitial sites of the bundled nanotube material. This phenomenon invoked a large downshift of the G(-) band in SWNTs, and a small downshift of the TM of the inner tube of DWNTs caused by expansion of the C--C bonds due to the charge transferred to the nanotubes, and the disappearance of the BWF profile through the screening effect of the interstitial Li(+) layers.

The First Layer of 4He, H2, and Ne Adsorbed on HiPco™ Carbon Nanotube Bundles

NASA Astrophysics Data System (ADS)

Vilches, O. E.; Ramachandran, S.; Wilson, T. A.; Dash, J. G.

2006-09-01

We summarize results from AC and DC heat capacity measurements of 4He, H2, and Ne adsorbed on HiPco™ purified, closed-end single-wall carbon nanotube bundles (SWNTB) for the first adsorbed layer. We find two regions in the coverage domain: below ≈1/3 monolayer the adsorbate occupies high binding energy sites, mostly the external grooves of the bundles, while above ≈1/3 monolayer the external graphene surface is covered. No phase transitions have been observed at any temperature for all the adsorbates, a range of T where two-dimensional phases and phase transitions are seen for the same adsorbates deposited on exfoliated graphite.

A Preliminary Study on a Specifically Expressed Arabidopsis Promotor in Vascular Bundle

NASA Astrophysics Data System (ADS)

Yun-hong, Gu; Chuan-xiao, Xie; Li-fang, Wu; Zeng-liang, Yu; Guang-yong, Qin; Yu-ping, Huo

2003-04-01

From a population of about 3500 single plants in Arabidopsis promoter trapping bank, one plant whose GUS-gene had been specifically expressed in vascular bundle, was screened by the method of gus tissue staining. The T-DNA flanking sequence was amplified using TAIL-PCR. This band will be purified and connected to TA cloning vector. After sequencing and searching in the genebank, its function will be demonatrated through transformation.

The quadrant method measuring four points is as a reliable and accurate as the quadrant method in the evaluation after anatomical double-bundle ACL reconstruction.

PubMed

Mochizuki, Yuta; Kaneko, Takao; Kawahara, Keisuke; Toyoda, Shinya; Kono, Norihiko; Hada, Masaru; Ikegami, Hiroyasu; Musha, Yoshiro

2017-11-20

The quadrant method was described by Bernard et al. and it has been widely used for postoperative evaluation of anterior cruciate ligament (ACL) reconstruction. The purpose of this research is to further develop the quadrant method measuring four points, which we named four-point quadrant method, and to compare with the quadrant method. Three-dimensional computed tomography (3D-CT) analyses were performed in 25 patients who underwent double-bundle ACL reconstruction using the outside-in technique. The four points in this study's quadrant method were defined as point1-highest, point2-deepest, point3-lowest, and point4-shallowest, in femoral tunnel position. Value of depth and height in each point was measured. Antero-medial (AM) tunnel is (depth1, height2) and postero-lateral (PL) tunnel is (depth3, height4) in this four-point quadrant method. The 3D-CT images were evaluated independently by 2 orthopaedic surgeons. A second measurement was performed by both observers after a 4-week interval. Intra- and inter-observer reliability was calculated by means of intra-class correlation coefficient (ICC). Also, the accuracy of the method was evaluated against the quadrant method. Intra-observer reliability was almost perfect for both AM and PL tunnel (ICC > 0.81). Inter-observer reliability of AM tunnel was substantial (ICC > 0.61) and that of PL tunnel was almost perfect (ICC > 0.81). The AM tunnel position was 0.13% deep, 0.58% high and PL tunnel position was 0.01% shallow, 0.13% low compared to quadrant method. The four-point quadrant method was found to have high intra- and inter-observer reliability and accuracy. This method can evaluate the tunnel position regardless of the shape and morphology of the bone tunnel aperture for use of comparison and can provide measurement that can be compared with various reconstruction methods. The four-point quadrant method of this study is considered to have clinical relevance in that it is a detailed and accurate tool for evaluating femoral tunnel position after ACL reconstruction. Case series, Level IV.

SF3M 2.0: improvement of 3D photo-reconstruction interface based on freely available software

NASA Astrophysics Data System (ADS)

Castillo, Carlos; James, Michael R.; Pérez, Rafael; Gómez, Jose A.

2016-04-01

During recent years, a number of tools based on Structure-from-Motion algorithms have been released for full image-based 3D reconstruction either freely (e.g. Bundler, PMVS2, VisualSFM, MicMac) or commercially (e.g. Agisoft PhotoScan). The SF3M interface was developed in Matlab® to use link software developments (VisualSFM, CloudCompare) and new applications to create a semi-automated workflow including reconstruction, georeferencing and point-cloud filtering, and has been tested for gully erosion assessment with terrestrial images (Castillo et al., 2015). The main aim of this work to provide an improved freely-available and easy-to-use alternative for 3D reconstruction intended for public agencies, non-profit organisations, researchers and other stakeholders interested in 3D modelling. In this communication we present SF3M 2.0, a new version of the graphical user interface. In this case, the SfM module is based on MicMac, an open-software tool (Pierrot-Deseilligny and Cléry, 2011) which provides advanced features such as camera calibration and constrained bundle adjustment using ground control points. SF3M 2.0 will be tested in two scenarios: a) using the same ground-based image set tested in Castillo et al. (2015) to compare the performance of both versions and b) using aerial images taken from a helium balloon to assess a gully network in a 40-hectares catchment. In this study we explore the advantages of SF3M 2.0, explain its operation and evaluate its accuracy and performance. This tool will be also available for free download. References Castillo, C., James, M.R., Redel-Macías, M. D., Pérez, R., and Gómez, J.A.: SF3M software: 3-D photo-reconstruction for non-expert users and its application to a gully network, SOIL, 1, 583-594. Pierrot-Deseilligny, M and Cléry, I. APERO, an Open Source Bundle Adjusment Software for Automatic Calibration and Orientation of a Set of Images. Proceedings of the ISPRS Commission V Symposium, Image Engineering and Vision Metrology, Trento, Italy, 2-4 March 2011.

Application of liquid-liquid interactions with single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Wang, Randy Kai-Wei

This study covers three important research topics related to the application of liquid-liquid interaction with single-walled carbon nanotubes (SWNTs). The first topic describes the removal of SWNT bundles from liquid suspensions of nanotubes. The key to this work includes the use of liquid-liquid interfaces to trap the SWNT bundles due to the free energy change of the system during the process. SWNTs pack into crystalline ropes that form bundles due to strong van der Waals attraction. Bundling diminishes mechanical and electronic properties because it could interrupt the electronic structure of the nanotubes. Also, the electronic devices based on as-grown nanotubes, which contains a mixture of individual nanotubes and nanotube bundles, make the electrical response unpredictable. We developed a new simple process to remove bundles by liquid-liquid interaction. SWNTs bundles are trapped at the interface because bundles stabilize the emulsions. Eliminating the use of ultracentrifugation to remove SWNT bundles enables large-scale production with reduced production costs and time savings. The second topic presented the swelling effect of the surfactant layer surrounding SWNTs with nonpolar solvents. Solvatochromic shifts in the absorbance and fluorescence spectra are observed when surfactant-stabilized aqueous SWNT suspensions are mixed with immiscible organic solvents. When aqueous surfactant-suspended SWNTs are mixed with certain solvents, the spectra closely match the peaks for SWNTs dispersed in only that solvent. These spectral changes suggest the hydrophobic region of the micelle surrounding SWNTs swells with the organic solvent when mixed. The solvatochromic shifts of the aqueous SWNT suspensions are reversible once the solvent evaporates. However, some surfactant-solvent systems show permanent changes to the fluorescence emission intensity after exposure to the organic solvent. The intensity of some large diameter SWNT (n, m) types increase by more than 175%. These differences are attributed to surfactant reorganization, which can improve nanotube coverage, resulting in decreased exposure to quenching mechanisms from the aqueous phase. The third topic describes the further study of the solvatochromism of the SWNTs. Since SWNTs are encapsulated with microenvironments of nonpolar solvents, it provides a new method to measure the photophysical properties of nanotubes in environments with known properties. Fluorescence and absorbance spectra of SWNTs show solvatochromic shifts in 16 nonpolar solvents, which are proportional to the solvent induction polarization. The photophysical properties of SWNTs were used to determine the relationship between the longitudinal polarizability and other nanotube properties, alpha11,|| ∝ 1/(R2E11 3). (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)

Sequence Bundles: a novel method for visualising, discovering and exploring sequence motifs

PubMed Central

2014-01-01

Background We introduce Sequence Bundles--a novel data visualisation method for representing multiple sequence alignments (MSAs). We identify and address key limitations of the existing bioinformatics data visualisation methods (i.e. the Sequence Logo) by enabling Sequence Bundles to give salient visual expression to sequence motifs and other data features, which would otherwise remain hidden. Methods For the development of Sequence Bundles we employed research-led information design methodologies. Sequences are encoded as uninterrupted, semi-opaque lines plotted on a 2-dimensional reconfigurable grid. Each line represents a single sequence. The thickness and opacity of the stack at each residue in each position indicates the level of conservation and the lines' curved paths expose patterns in correlation and functionality. Several MSAs can be visualised in a composite image. The Sequence Bundles method is designed to favour a tangible, continuous and intuitive display of information. Results We have developed a software demonstration application for generating a Sequence Bundles visualisation of MSAs provided for the BioVis 2013 redesign contest. A subsequent exploration of the visualised line patterns allowed for the discovery of a number of interesting features in the dataset. Reported features include the extreme conservation of sequences displaying a specific residue and bifurcations of the consensus sequence. Conclusions Sequence Bundles is a novel method for visualisation of MSAs and the discovery of sequence motifs. It can aid in generating new insight and hypothesis making. Sequence Bundles is well disposed for future implementation as an interactive visual analytics software, which can complement existing visualisation tools. PMID:25237395

From Biological Cilia to Artificial Flow Sensors: Biomimetic Soft Polymer Nanosensors with High Sensing Performance

PubMed Central

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Karavitaki, K. Domenica; Warkiani, Majid Ebrahimi; Miao, Jianmin; Corey, David P.; Triantafyllou, Michael

2016-01-01

We report the development of a new class of miniature all-polymer flow sensors that closely mimic the intricate morphology of the mechanosensory ciliary bundles in biological hair cells. An artificial ciliary bundle is achieved by fabricating bundled polydimethylsiloxane (PDMS) micro-pillars with graded heights and electrospinning polyvinylidenefluoride (PVDF) piezoelectric nanofiber tip links. The piezoelectric nature of a single nanofiber tip link is confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Rheology and nanoindentation experiments are used to ensure that the viscous properties of the hyaluronic acid (HA)-based hydrogel are close to the biological cupula. A dome-shaped HA hydrogel cupula that encapsulates the artificial hair cell bundle is formed through precision drop-casting and swelling processes. Fluid drag force actuates the hydrogel cupula and deflects the micro-pillar bundle, stretching the nanofibers and generating electric charges. Functioning with principles analogous to the hair bundles, the sensors achieve a sensitivity and threshold detection limit of 300 mV/(m/s) and 8 μm/s, respectively. These self-powered, sensitive, flexible, biocompatibale and miniaturized sensors can find extensive applications in navigation and maneuvering of underwater robots, artificial hearing systems, biomedical and microfluidic devices. PMID:27622466

Application of a transient heat transfer model for bundled, multiphase pipelines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, T.S.; Clapham, J.; Danielson, T.J.

1996-12-31

A computer model has been developed which accurately describes transient heat transfer in pipeline bundles. An arbitrary number of internal pipelines containing different fluids, flowing in either direction along with the input of heat to one or more of the fluids can be accommodated. The model is coupled to the transient, multiphase flow simulator OLGA. The lines containing the multiphase production fluids are modeled by OLGA, and the heat transfer between the internal lines, carrier pipe, and surroundings is handled by the bundle model. The model has been applied extensively to the design of a subsea, heated bundle system formore » the Britannia gas condensate field in the North Sea. The 15-km bundle system contains a 14{double_prime} production line, an 8{double_prime} test line, a 3{double_prime} methanol line, and a 12{double_prime} internal heating medium line within a 37.25{double_prime} carrier. The heating medium (water) flows in the internal heating medium line and in the annulus at 82,500 BPD. The primary purpose of the bundle system is to avoid the formation of hydrates. A secondary purpose is to avoid the deposition of paraffin. The bundle model was used to (1) compare the merits of two coaxial lines vs. a single bundle; (2) optimize the insulation levels on the carrier and internal lines; (3) determine the minimum time required to heat up the bundle; (4) determine heat input requirements to avoid hydrates throughout the field life, (5) determine temperature profiles along the lines for a range of production rates; (6) study ruptures of the production line into the bundle annulus; (7) determine minimum temperatures during depressurization; and (8) determine cool-down times. The results of these studies were used to size lines, select insulation levels, assess erosion potential, design for thermal expansion-induced stresses, and to select materials of construction.« less

Process-Hardened, Multi-Analyte Sensor for Characterizing Rocket Plume Constituents

NASA Technical Reports Server (NTRS)

Goswami, Kisholoy

2011-01-01

A multi-analyte sensor was developed that enables simultaneous detection of rocket engine combustion-product molecules in a launch-vehicle ground test stand. The sensor was developed using a pin-printing method by incorporating multiple sensor elements on a single chip. It demonstrated accurate and sensitive detection of analytes such as carbon dioxide, carbon monoxide, kerosene, isopropanol, and ethylene from a single measurement. The use of pin-printing technology enables high-volume fabrication of the sensor chip, which will ultimately eliminate the need for individual sensor calibration since many identical sensors are made in one batch. Tests were performed using a single-sensor chip attached to a fiber-optic bundle. The use of a fiber bundle allows placement of the opto-electronic readout device at a place remote from the test stand. The sensors are rugged for operation in harsh environments.

Aligning Arrays of Lenses and Single-Mode Optical Fibers

NASA Technical Reports Server (NTRS)

Liu, Duncan

2004-01-01

A procedure now under development is intended to enable the precise alignment of sheet arrays of microscopic lenses with the end faces of a coherent bundle of as many as 1,000 single-mode optical fibers packed closely in a regular array (see Figure 1). In the original application that prompted this development, the precise assembly of lenses and optical fibers serves as a single-mode spatial filter for a visible-light nulling interferometer. The precision of alignment must be sufficient to limit any remaining wavefront error to a root-mean-square value of less than 1/10 of a wavelength of light. This wavefront-error limit translates to requirements to (1) ensure uniformity of both the lens and fiber arrays, (2) ensure that the lateral distance from the central axis of each lens and the corresponding optical fiber is no more than a fraction of a micron, (3) angularly align the lens-sheet planes and the fiber-bundle end faces to within a few arc seconds, and (4) axially align the lenses and the fiber-bundle end faces to within tens of microns of the focal distance. Figure 2 depicts the apparatus used in the alignment procedure. The beam of light from a Zygo (or equivalent) interferometer is first compressed by a ratio of 20:1 so that upon its return to the interferometer, the beam will be magnified enough to enable measurement of wavefront quality. The apparatus includes relay lenses that enable imaging of the arrays of microscopic lenses in a charge-coupled-device (CCD) camera that is part of the interferometer. One of the arrays of microscopic lenses is mounted on a 6-axis stage, in proximity to the front face of the bundle of optical fibers. The bundle is mounted on a separate stage. A mirror is attached to the back face of the bundle of optical fibers for retroreflection of light. When a microscopic lens and a fiber are aligned with each other, the affected portion of the light is reflected back by the mirror, recollimated by the microscopic lens, transmitted through the relay lenses and the beam compressor/expander, then split so that half goes to a detector and half to the interferometer. The output of the detector is used as a feedback control signal for the six-axis stage to effect alignment.

Study of multi-muon bundles in cosmic ray showers detected with the DELPHI detector at LEP

NASA Astrophysics Data System (ADS)

Delphi Collaboration; Abreu, P.; Adam, W.; Adzic, P.; Albrecht, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P. P.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W.-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G. J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K.-H.; Begalli, M.; Behrmann, A.; Ben-Haim, E.; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, M.; Bertrand, D.; Besancon, M.; Besson, N.; Bloch, D.; Blom, M.; Bluj, M.; Bonesini, M.; Boonekamp, M.; Booth, P. S. L.; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I.; Bracko, M.; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J. M.; Buschbeck, B.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Castro, N.; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, S. U.; Cieslik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, M. J.; Crennell, D.; Cuevas, J.; D'Hondt, J.; da Silva, T.; da Silva, W.; Della Ricca, G.; de Angelis, A.; de Boer, W.; de Clercq, C.; de Lotto, B.; de Maria, N.; de Min, A.; de Paula, L.; di Ciaccio, L.; di Simone, A.; Doroba, K.; Drees, J.; Eigen, G.; Ekelof, T.; Ellert, M.; Elsing, M.; Espirito Santo, M. C.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernandez, J.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; Garcia, C.; Gavillet, Ph.; Gazis, E.; Gokieli, R.; Golob, B.; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Herr, H.; Hoffman, J.; Holmgren, S.-O.; Holt, P. J.; Houlden, M. A.; Jackson, J. N.; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, E. K.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Kernel, G.; Kersevan, B. P.; Kerzel, U.; King, B. T.; Kjaer, N. J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J. H.; Lopez, J. M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J.-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; McNulty, R.; Meroni, C.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Moenig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Mueller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nicolaidou, R.; Nikolenko, M.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J. P.; Palka, H.; Papadopoulou, Th. D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, M. E.; Polok, G.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Rames, J.; Read, A.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Ridky, J.; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, P.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Sander, C.; Savoy-Navarro, A.; Schwickerath, U.; Sekulin, R.; Shellard, R. C.; Siebel, M.; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Taffard, A. C.; Tegenfeldt, F.; Timmermans, J.; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M.-L.; Tyapkin, I. A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, G.; van Dam, P.; van Eldik, J.; van Remortel, N.; van Vulpen, I.; Vegni, G.; Veloso, F.; Venus, W.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, A. J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zhuravlov, V.; Zimin, N. I.; Zintchenko, A.; Zupan, M.

2007-11-01

The DELPHI detector at LEP has been used to measure multi-muon bundles originating from cosmic ray interactions with air. The cosmic events were recorded in “parasitic mode” between individual e+e- interactions and the total live time of this data taking is equivalent to 1.6 × 106 s. The DELPHI apparatus is located about 100 m underground and the 84 metres rock overburden imposes a cutoff of about 52 GeV/c on muon momenta. The data from the large volume Hadron Calorimeter allowed the muon multiplicity of 54,201 events to be reconstructed. The resulting muon multiplicity distribution is compared with the prediction of the Monte Carlo simulation based on CORSIKA/QGSJET01. The model fails to describe the abundance of high multiplicity events. The impact of QGSJET internal parameters on the results is also studied.

Specialised sympathetic neuroeffector associations in rat iris arterioles

PubMed Central

SANDOW, SHAUN L.; WHITEHOUSE, DREW; HILL, CARYL E.

1998-01-01

Vascular sympathetic neuroeffector associations have been examined in rat iris arterioles using serial section electron microscopy and reconstruction techniques. Examination of random sections showed that, of all profiles of varicosities (199) seen to lie closer than 4 μm to vascular smooth muscle cells, only a small proportion (29/199) were found in close association with vascular smooth muscle cells, where adjacent membranes were separated by less than 100 nm. However, serial section examination, from intervaricose region to intervaricose region, of 79 varicosities similarly observed lying within 4 μm of vascular smooth muscle cells showed that 54 formed close associations with vascular smooth muscle cells. In serial sections, all these varicosities were also closely associated with melanocytes and of the 25 remaining varicosities, 22 formed close associations with melanocytes alone, whilst 3 did not come into close association with any effector cell. The increased observation of close associations with vascular smooth muscle cells in serial sections, compared with random sections, is consistent with the demonstration that the area of contact only occupies, on average, a small percentage (5%) of the total surface area of the varicosity as seen in the 3-dimensional reconstructions. In both random and serial sections, close associations were observed between varicosities and vascular smooth muscle cells or melanocytes irrespective of whether fibres were present singly or in small nerve bundles. Three-dimensional reconstruction of associations of varicosities and vascular smooth muscle cells demonstrated several common features, such as accumulations of synaptic vesicles and loss of Schwann cell covering at the region of membrane facing the effector cell. The similarity in the appearance of the neuroeffector association seen in this study and those described in previous studies provides evidence for the existence of a common sympathetic neuroeffector association, irrespective of the receptor subtype involved in neurotransmission. PMID:9568560

Validity of GNRB® arthrometer compared to Telos™ in the assessment of partial anterior cruciate ligament tears.

PubMed

Lefevre, N; Bohu, Y; Naouri, J F; Klouche, S; Herman, S

2014-02-01

The main goal of this study was to compare the results of the GNRB(®) arthrometer to those of Telos™ in the diagnosis of partial thickness tears of the anterior cruciate ligament (ACL). A prospective study performed January-December 2011 included all patients presenting with a partial or full-thickness ACL tears without ACL reconstruction and with a healthy contralateral knee. Anterior laxity was measured in all patients by the Telos™ and GNRB(®) devices. This series included 139 patients, mean age 30.7 ± 9.3 years. Arthroscopic reconstruction was performed in 109 patients, 97 for complete tears and 12 single bundle reconstructions for partial thickness tears. Conservative treatment was proposed in 30 patients with a partial thickness tear. The correlation between the two devices was evaluated by the Spearman coefficient. The optimal laxity thresholds were determined with ROC curves, and the diagnostic value of the tests was assessed by the area under the curve (AUC). The differential laxities of full and partial thickness tears were significantly different with the two tests. The correlation between the results of laxity measurement with the two devices was fair, with the strongest correlation between Telos™ 250 N and GNRB(®) 250 N (r = 0.46, p = 0.00001). Evaluation of the AUC showed that the informative value of all tests was fair with the best results with the GNRB(®) 250 N: AUC = 0.89 [95 % CI 0.83-0.94]. The optimal differential laxity threshold with the GNRB(®) 250 N was 2.5 mm (Se = 84 %, Sp = 81 %). The diagnostic value of GNRB(®) was better than Telos™ for ACL partial thickness tears.

Frontal plane knee mechanics and medial cartilage MR relaxation times in individuals with ACL reconstruction : A pilot study

PubMed Central

Kumar, Deepak; Kothari, Abbas; Souza, Richard B.; Wu, Samuel; Ma, C. Benjamin; Li, Xiaojuan

2014-01-01

Background The objective of this pilot study was to evaluate cartilage T1ρ and T2 relaxation times and knee mechanics during walking and drop-landing for individuals with anterior cruciate ligament reconstruction (ACL-R). Methods Nine patients (6 men and 3 women, Age 35.8±5.4 years, BMI 23.5±2.5 kg/m2) participated 1.5±0.8 years after single-bundle two-tunnel ACL reconstruction. Peak knee adduction moment (KAM), flexion moment (KFM), extension moment (KEM), and peak varus were calculated from kinematic and kinetic data obtained during walking and drop-landing tasks. T1ρ and T2 times were calculated for medial femur (MF), and medial tibia (MT) cartilage and compared between subjects with low KAM and high KAM. Biomechanical variables were compared between limbs. Results The high KAM group had higher T1ρ for MT (p = 0.01), central MT (p = 0.05), posterior MF (p = 0.04), posterior MT (p = 0.01); and higher T2 for MT (p = 0.02), MF (p = 0.05) posterior MF (p = 0.002) and posterior MT (p = 0.01). During walking, ACL-R knees had greater flexion at initial contact (p =0.04), and lower KEM (p = 0.02). During drop-landing, the ACL-R knees had lower KAM (p = 0.03) and KFM (p = 0.002). Conclusion Patients with ACL-R who have higher KAM during walking had elevated MR relaxation times in the medial knee compartments. These data suggest that those individuals who have undergone ACL-R and have higher frontal plane loading, may be at a greater risk of knee osteoarthritis. PMID:24993277

Impact of a value-based insurance design for physical therapy to treat back pain on care utilization and cost.

PubMed

Maeng, Daniel D; Graboski, Anthony; Allison, Peiling L; Fisher, Dorothy Y; Bulger, John B

2017-01-01

To assess the impact of a value-based insurance design providing enhanced access to physical therapy (PT) for treatment of back pain on treatment patterns and cost of care. A retrospective analysis of claims data obtained from Geisinger Health Plan (GHP). In April 2013, GHP began offering "PT bundle" - i.e., a bundle of up to five PT visits for a single one-time copay that can be renewed for another bundle of five PT visits - for its employer-based plan members with back pain. A cohort of GHP members who were preauthorized for the PT bundle were compared against a contemporaneous cohort of GHP members who were preauthorized for PT under the standard per-visit copay arrangement between January 2013 and October 2014. Among the PT bundle cohort, the PT visit rate during the first 9 months since the PT preauthorization date had dramatically increased and then gradually decreased in subsequent months. The PT bundle was also associated with 29%-35% short-term reductions in emergency department visits and with 12%-20% reductions in primary care visits after 6 months. No significant impact on hospitalization or cost was observed. Implementation of the PT bundle appears to have led to a change in the treatment pattern of back pain that is more consistent with the recommended guidelines to use more conservative management such as PT as the first-line treatment for back pain.

Classical geometric resolution of the Einstein—Podolsky—Rosen paradox

PubMed Central

Ne'eman, Yuval

1983-01-01

I show that, in the geometry of a fiber bundle describing a gauge theory, curvature and parallel transport ensure and impose nonseparability. The “Einstein—Podolsky—Rosen paradox” is thus resolved “classically.” I conjecture that the ostentatiously “implausible” features of the quantum treatment are due to the fact that space—time separability, a basic assumption of single-particle nonrelativistic quantum mechanics, does not fit the bundle geometry of the complete physics. PMID:16593392

Rigorous accuracy assessment for 3D reconstruction using time-series Dual Fluoroscopy (DF) image pairs

NASA Astrophysics Data System (ADS)

Al-Durgham, Kaleel; Lichti, Derek D.; Kuntze, Gregor; Ronsky, Janet

2017-06-01

High-speed biplanar videoradiography, or clinically referred to as dual fluoroscopy (DF), imaging systems are being used increasingly for skeletal kinematics analysis. Typically, a DF system comprises two X-ray sources, two image intensifiers and two high-speed video cameras. The combination of these elements provides time-series image pairs of articulating bones of a joint, which permits the measurement of bony rotation and translation in 3D at high temporal resolution (e.g., 120-250 Hz). Assessment of the accuracy of 3D measurements derived from DF imaging has been the subject of recent research efforts by several groups, however with methodological limitations. This paper presents a novel and simple accuracy assessment procedure based on using precise photogrammetric tools. We address the fundamental photogrammetry principles for the accuracy evaluation of an imaging system. Bundle adjustment with selfcalibration is used for the estimation of the system parameters. The bundle adjustment calibration uses an appropriate sensor model and applies free-network constraints and relative orientation stability constraints for a precise estimation of the system parameters. A photogrammetric intersection of time-series image pairs is used for the 3D reconstruction of a rotating planar object. A point-based registration method is used to combine the 3D coordinates from the intersection and independently surveyed coordinates. The final DF accuracy measure is reported as the distance between 3D coordinates from image intersection and the independently surveyed coordinates. The accuracy assessment procedure is designed to evaluate the accuracy over the full DF image format and a wide range of object rotation. Experiment of reconstruction of a rotating planar object reported an average positional error of 0.44 +/- 0.2 mm in the derived 3D coordinates (minimum 0.05 and maximum 1.2 mm).

Buckling analysis of carbon nanotube bundles under axial compressive, bending and torsional loadings via a structural mechanics model

NASA Astrophysics Data System (ADS)

Lashkari Zadeh, Ali; Shariati, Mahmoud; Torabi, Hamid

2012-11-01

A structural mechanics model is employed for the investigation of the buckling behavior of carbon nanotube bundles of three single-walled carbon nanotubes (SWCNTs) under axial compressive, bending and torsional loadings. The effects of van der Waals (vdW) forces are further modeled using a nonlinear spring element.The effects of different types of boundary conditions are studied for nanotubes with various aspect ratios. The results reveal that bundles comprising longer SWCNTs exhibit lower critical buckling load. Moreover, for the fixed-free boundary condition the rate of critical buckling load reduction is highest, while the lowest critical buckling load occurs. Simulations show good agreement between our model and molecular dynamics results.

Polymer-based doping control for performance enhancement of wet-processed short-channel CNTFETs

NASA Astrophysics Data System (ADS)

Hartmann, Martin; Schubel, René; Claus, Martin; Jordan, Rainer; Schulz, Stefan E.; Hermann, Sascha

2018-01-01

The electrical transport properties of short-channel transistors based on single-walled carbon nanotubes (CNT) are significantly affected by bundling along with solution processing. We report that especially high off currents of CNT transistors are not only related to the incorporation of metallic CNTs but also to the incorporation of CNT bundles. By applying device passivation with poly(4-vinylpyridine), the impact of CNT bundling on the device performance can be strongly reduced due to increased gate efficiency as well as reduced oxygen and water-induced p-type doping, boosting essential field-effect transistor performance parameters by several orders of magnitude. Moreover, this passivation approach allows the hysteresis and threshold voltage of CNT transistors to be tuned.

Size effects of single-walled carbon nanotubes on in vivo and in vitro pulmonary toxicity

PubMed Central

Fujita, Katsuhide; Fukuda, Makiko; Endoh, Shigehisa; Maru, Junko; Kato, Haruhisa; Nakamura, Ayako; Shinohara, Naohide; Uchino, Kanako; Honda, Kazumasa

2015-01-01

Abstract To elucidate the effect of size on the pulmonary toxicity of single-wall carbon nanotubes (SWCNTs), we prepared two types of dispersed SWCNTs, namely relatively thin bundles with short linear shapes (CNT-1) and thick bundles with long linear shapes (CNT-2), and conducted rat intratracheal instillation tests and in vitro cell-based assays using NR8383 rat alveolar macrophages. Total protein levels, MIP-1α expression, cell counts in BALF, and histopathological examinations revealed that CNT-1 caused pulmonary inflammation and slower recovery and that CNT-2 elicited acute lung inflammation shortly after their instillation. Comprehensive gene expression analysis confirmed that CNT-1-induced genes were strongly associated with inflammatory responses, cell proliferation, and immune system processes at 7 or 30 d post-instillation. Numerous genes were significantly upregulated or downregulated by CNT-2 at 1 d post-instillation. In vitro assays demonstrated that CNT-1 and CNT-2 SWCNTs were phagocytized by NR8383 cells. CNT-2 treatment induced cell growth inhibition, reactive oxygen species production, MIP-1α expression, and several genes involved in response to stimulus, whereas CNT-1 treatment did not exert a significant impact in these regards. These results suggest that SWCNTs formed as relatively thin bundles with short linear shapes elicited delayed pulmonary inflammation with slower recovery. In contrast, SWCNTs with a relatively thick bundle and long linear shapes sensitively induced cellular responses in alveolar macrophages and elicited acute lung inflammation shortly after inhalation. We conclude that the pulmonary toxicity of SWCNTs is closely associated with the size of the bundles. These physical parameters are useful for risk assessment and management of SWCNTs. PMID:25865113

MRA of the skin: mapping for advanced breast reconstructive surgery.

PubMed

Thimmappa, N D; Vasile, J V; Ahn, C Y; Levine, J L; Prince, M R

2018-02-27

Autologous breast reconstruction using muscle-sparing free flaps are becoming increasingly popular, although microvascular free flap reconstruction has been utilised for autologous breast reconstructions for >20 years. This innovative microsurgical technique involves meticulous dissection of artery-vein bundle (perforators) responsible for perfusion of the subcutaneous fat and skin of the flap; however, due to unpredictable anatomical variations, preoperative imaging of the donor site to select appropriate perforators has become routine. Preoperative imaging also reduces operating time and enhances the surgeon's confidence in choosing the appropriate donor site for harvesting flaps. Although computed tomography angiography has been widely used for preoperative imaging, concerns over excessive exposure to ionising radiation and poor iodinated contrast agent enhancement of the intramuscular perforator course has made magnetic resonance angiography, the first choice imaging modality in our centre. Magnetic resonance angiography with specific post-processing of the images has established itself as a reliable method for mapping tiny perforator vessels. Multiple donor sites can be imaged in a single setting without concern for ionising radiation exposure. This provides anatomical information of more reconstruction donor site options, so that a surgeon can design a flap of tissue centralised around the best perforator, as well as a back-up perforator, and even a back-up flap option located on a different region of the body. This information is especially helpful in patients with a history of scar tissue from previous surgeries, where the primary choice perforator is found to be damaged or unsuitable intraoperatively. In addition, chest magnetic resonance angiography evaluates recipient site blood vessel suitability including vessel diameters, course, and branching patterns. In this article we provide a broad overview of various skin flaps, clinical indications, advantages and disadvantages of each of these flaps, basic imaging technique, along with advanced sequences for visualising tiny arteries in the groin and in the chest. Post-processing techniques, structure of the report and how automation of the reporting system improves workflow is described. We also describe applications of magnetic resonance angiography in postoperative imaging. Copyright © 2018 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Morphologic evaluation of remnant anterior cruciate ligament bundles after injury with three-dimensional computed tomography.

PubMed

Adachi, Nobuo; Ochi, Mitsuo; Takazawa, Kobun; Ishifuro, Minoru; Deie, Masataka; Nakamae, Atsuo; Kamei, Goki

2016-01-01

This study aimed to investigate the morphological patterns of remnant anterior cruciate ligament bundles after injury (ACL remnant) on three-dimensional computed tomography (3DCT) and compare them with those on arthroscopy. Sixty-three patients (33 males and 30 females; mean age 25.2 ± 10.1 years) who had undergone primary ACL reconstruction between March 2011 and December 2012 were included in this study. The average durations between traumas and 3DCT and between 3DCT and surgery were 101.7 ± 87.2 and 38.2 ± 38.7 days, respectively. ACL remnants were classified into four morphological patterns on 3DCT. 3DCT findings were compared with arthroscopic findings with and without probing. The morphological patterns of the ACL remnants on 3DCT were well matched with those on arthroscopy without probing (the concordance rate was 77.8%). However, the concordance rate was reduced to 49.2% when arthroscopic probing was used to confirm the femoral attachment of ACL remnants (p ≤ 0.05). This study demonstrates that the morphological patterns of ACL remnants on 3DCT were well matched with those on arthroscopy without probing. Therefore, the technique can be useful for preoperative planning of the ACL reconstruction or informed consent to the patients. However, for definitive diagnosis, arthroscopic probing is required. IV.

Studies on sodium boiling phenomena in out of pile rod bundles for various accidental situations in Liquid Metal Fast Breeder Reactors (LMFBR) experiments and interpretations

NASA Astrophysics Data System (ADS)

Seiler, J. M.; Rameau, B.

Bundle sodium boiling in nominal geometry for different accident conditions is reviewed. Voiding of a subassembly is controlled by not only hydrodynamic effects but mainly by thermal effects. There is a strong influence of the thermal inertia of the bundle material compared to the sodium thermal inertia. Flow instability, during a slow transient, can be analyzed with numerical tools and estimated using simplified approximations. Stable boiling operational conditions under bundle mixed convection (natural convection in the reactor) can be predicted. Voiding during a fast transient can be approximated from single channel calculations. The phenomenology of boiling behavior for a subassembly with inlet completely blocked, submitted to decay heat and lateral cooling; two-phase sodium flow pressure drop in a tube of large hydraulic diameter under adiabatic conditions; critical flow phenomena and voiding rate under high power, slow transient conditions; and onset of dry out under local boiling remains problematical.

Quantum correlation enhanced super-resolution localization microscopy enabled by a fibre bundle camera

PubMed Central

Israel, Yonatan; Tenne, Ron; Oron, Dan; Silberberg, Yaron

2017-01-01

Despite advances in low-light-level detection, single-photon methods such as photon correlation have rarely been used in the context of imaging. The few demonstrations, for example of subdiffraction-limited imaging utilizing quantum statistics of photons, have remained in the realm of proof-of-principle demonstrations. This is primarily due to a combination of low values of fill factors, quantum efficiencies, frame rates and signal-to-noise characteristic of most available single-photon sensitive imaging detectors. Here we describe an imaging device based on a fibre bundle coupled to single-photon avalanche detectors that combines a large fill factor, a high quantum efficiency, a low noise and scalable architecture. Our device enables localization-based super-resolution microscopy in a non-sparse non-stationary scene, utilizing information on the number of active emitters, as gathered from non-classical photon statistics. PMID:28287167

Simulations of Simple Nanomachines in Carbon Nanotude Bundles Based on Chirality

DTIC Science & Technology

2008-12-01

forces . Cornwell, C. F., D. L. Majure , R. W. Haskins, N. J. Lee, R. M. Ebeling, R. D. Maier, C. P. Marsh, A. J. Bednar, R.A. Kirgan, and C. R...of single- wall carbon nanotubes induced by intertube van der Waals forces . Physical Review, B 77, 153405 Majure , D. L., R. W. Haskins, R. M...BUNDLES BASED ON CHIRALITY D. L. Majure *, R. W. Haskins, N. J. Lee, C. R. Welch U.S. Army Engineer Research and Development Center, 3909 Halls Ferry

Flexible ex vivo phantoms for validation of diffusion tensor tractography on a clinical scanner.

PubMed

Watanabe, Makoto; Aoki, Shigeki; Masutani, Yoshitaka; Abe, Osamu; Hayashi, Naoto; Masumoto, Tomohiko; Mori, Harushi; Kabasawa, Hiroyuki; Ohtomo, Kuni

2006-11-01

The aim of this study was to develop ex vivo diffusion tensor (DT) flexible phantoms. Materials were bundles of textile threads of cotton, monofilament nylon, rayon, and polyester bunched with spiral wrapping bands and immersed in water. DT images were acquired on a 1.5-Tesla clinical magnetic resonance scanner using echo planar imaging sequences with 15 motion probing gradient directions. DT tractography with seeding and a line-tracking method was carried out by software originally developed on a PC-based workstation. We observed relatively high fractional anisotropy on the polyester phantom and were able to reconstruct tractography. Straight tracts along the bundle were displayed when it was arranged linearly. It was easy to bend arcuately or bifurcate at one end; and tracts followed the course of the bundle, whether it was curved or branched and had good agreement with direct visual observation. Tractography with the other fibers was unsuccessful. The polyester phantom revealed a diffusion anisotropic structure according to its shape and would be utilizable repeatedly under the same conditions, differently from living central neuronal system. It would be useful to validate DT sequences and to optimize an algorithm or parameters of DT tractography software. Additionally, the flexibility of the phantom would enable us to model human axonal projections.

Adsorption site analysis of impurity embedded single-walled carbon nanotube bundles

USGS Publications Warehouse

Agnihotri, S.; Mota, J.P.B.; Rostam-Abadi, M.; Rood, M.J.

2006-01-01

Bundle morphology and adsorptive contributions from nanotubes and impurities are studied both experimentally and by simulation using a computer-aided methodology, which employs a small physisorbed probe molecule to explore the porosity of nanotube samples. Grand canonical Monte Carlo simulation of nitrogen adsorption on localized sites of a bundle is carried out to predict adsorption in its accessible internal pore volume and on its external surface as a function of tube diameter. External adsorption is split into the contributions from the clean surface of the outermost nanotubes of the bundle and from the surface of the impurities. The site-specific isotherms are then combined into a global isotherm for a given sample using knowledge of its tube-diameter distribution obtained by Raman spectroscopy. The structural parameters of the sample, such as the fraction of open-ended nanotubes and the contributions from impurities and nanotube bundles to total external surface area, are determined by fitting the experimental nitrogen adsorption data to the simulated isotherm. The degree of closure between experimental and calculated adsorption isotherms for samples manufactured by two different methods, to provide different nanotube morphology and contamination level, further strengthens the validity and resulting interpretations based on the proposed approach. The average number of nanotubes per bundle and average bundle size, within a sample, are also quantified. The proposed method allows for extrapolation of adsorption properties to conditions where the purification process is 100% effective at removing all impurities and opening access to all intrabundle adsorption sites. ?? 2006 Elsevier Ltd. All rights reserved.

Atlas-guided cluster analysis of large tractography datasets.

PubMed

Ros, Christian; Güllmar, Daniel; Stenzel, Martin; Mentzel, Hans-Joachim; Reichenbach, Jürgen Rainer

2013-01-01

Diffusion Tensor Imaging (DTI) and fiber tractography are important tools to map the cerebral white matter microstructure in vivo and to model the underlying axonal pathways in the brain with three-dimensional fiber tracts. As the fast and consistent extraction of anatomically correct fiber bundles for multiple datasets is still challenging, we present a novel atlas-guided clustering framework for exploratory data analysis of large tractography datasets. The framework uses an hierarchical cluster analysis approach that exploits the inherent redundancy in large datasets to time-efficiently group fiber tracts. Structural information of a white matter atlas can be incorporated into the clustering to achieve an anatomically correct and reproducible grouping of fiber tracts. This approach facilitates not only the identification of the bundles corresponding to the classes of the atlas; it also enables the extraction of bundles that are not present in the atlas. The new technique was applied to cluster datasets of 46 healthy subjects. Prospects of automatic and anatomically correct as well as reproducible clustering are explored. Reconstructed clusters were well separated and showed good correspondence to anatomical bundles. Using the atlas-guided cluster approach, we observed consistent results across subjects with high reproducibility. In order to investigate the outlier elimination performance of the clustering algorithm, scenarios with varying amounts of noise were simulated and clustered with three different outlier elimination strategies. By exploiting the multithreading capabilities of modern multiprocessor systems in combination with novel algorithms, our toolkit clusters large datasets in a couple of minutes. Experiments were conducted to investigate the achievable speedup and to demonstrate the high performance of the clustering framework in a multiprocessing environment.

Simultaneous anatomic reconstruction of the acromioclavicular and coracoclavicular ligaments using a single tendon graft.

PubMed

Shin, Sang-Jin; Campbell, Sean; Scott, Jonathan; McGarry, Michelle H; Lee, Thay Q

2014-09-01

The purpose of this study was to introduce a novel surgical technique for simultaneous anatomic reconstruction of the acromioclavicular and coracoclavicular ligaments using a single tendon graft and to compare its biomechanical characteristics to those of a coracoid cerclage reconstruction of the coracoclavicular ligaments. Six matched pairs of human acromioclavicular joints with an average age of 54.8 ± 7.8 years were used. One shoulder from each pair received the single tendon acromioclavicular-coracoclavicular reconstruction; the contralateral shoulder received the coracoid cerclage reconstruction. Bovine extensor tendon was used for both techniques. The single tendon acromioclavicular-coracoclavicular reconstruction technique provided anatomic restoration of the two coracoclavicular ligaments and the superior and inferior acromioclavicular ligaments simultaneously using one coracoid hole, one acromion hole, and two clavicular holes with interference screws. Anterior-posterior and superior-inferior translations were quantified for all specimens before and after reconstruction, followed by load to failure testing. Following coracoid cerclage reconstruction, total anterior-posterior translation was significantly greater than intact (10.0 ± 5.7 mm; p = 0.008). Following single tendon acromioclavicular-coracoclavicular reconstruction, there was no significant difference in anterior-posterior translation compared to intact (-1.6 ± 2.2 mm; n.s.). The coracoid cerclage technique demonstrated significantly greater anterior-posterior translation than the single tendon acromioclavicular-coracoclavicular technique (p = 0.007). Both techniques restored superior-inferior translation to the intact condition (n.s.). Ultimate load, deformation at ultimate load, and energy absorbed at ultimate load were significantly greater after acromioclavicular-coracoclavicular reconstruction than after coracoid cerclage reconstruction (p < 0.05). This novel single tendon anatomic acromioclavicular-coracoclavicular reconstruction provided greater stability and stronger load to failure characteristics than the isolated coracoid cerclage reconstruction. A simultaneous acromioclavicular-coracoclavicular reconstruction technique using a single free tendon graft provided anatomic reconstruction of the conoid, trapezoid, and superior and inferior acromioclavicular ligaments and may reduce postoperative subluxation.

Revision surgery in anterior cruciate ligament reconstruction: a cohort study of 17,682 patients from the Swedish National Knee Ligament Register.

PubMed

Desai, Neel; Andernord, Daniel; Sundemo, David; Alentorn-Geli, Eduard; Musahl, Volker; Fu, Freddie; Forssblad, Magnus; Samuelsson, Kristian

2017-05-01

To investigate the association between surgical variables and the risk of revision surgery after ACL reconstruction in the Swedish National Knee Ligament Register. This cohort study was based on data from the Swedish National Knee Ligament Register. Patients who underwent primary single-bundle ACL reconstruction with hamstring tendon were included. Follow-up started with primary ACL reconstruction and ended with ACL revision surgery or on 31 December, 2014, whichever occurred first. Details on surgical technique were collected using an online questionnaire. All group comparisons were made in relation to an "anatomic" reference group, comprised of essential AARSC items, defined as utilization of accessory medial portal drilling, anatomic tunnel placement, visualization of insertion sites and pertinent landmarks. Study end-point was revision surgery. A total of 108 surgeons (61.7%) replied to the questionnaire. A total of 17,682 patients were included [n = 10,013 males (56.6%) and 7669 females (43.4%)]. The overall revision rate was 3.1%. Older age as well as cartilage injury evident at index surgery was associated with a decreased risk of revision surgery. The group using transtibial drilling and non-anatomic bone tunnel placement was associated with a lower risk of revision surgery [HR 0.694 (95% CI 0.490-0.984); P = 0.041] compared with the anatomic reference group. The anatomic reference group showed no difference in risk of revision surgery compared with the transtibial drilling groups with partial anatomic [HR 0.759 (95% CI 0.548-1.051), n.s.] and anatomic tunnel placement [HR 0.944 (95% CI 0.718-1.241), n.s.]. The anatomic reference group showed a decreased risk of revision surgery compared with the transportal drilling group with anatomic placement [HR 1.310 (95% CI 1.047-1.640); P = 0.018]. Non-anatomic bone tunnel placement via transtibial drilling resulted in the lowest risk of revision surgery after ACL reconstruction. The risk of revision surgery increased when using transportal drilling. Performing anatomic ACL reconstruction utilizing eight selected essential items from the AARSC lowered the risk of revision surgery associated with transportal drilling and anatomic bone tunnel placement. Detailed knowledge of surgical technique using the AARSC predicts the risk of ACL revision surgery. III.

Can we Use Low-Cost 360 Degree Cameras to Create Accurate 3d Models?

NASA Astrophysics Data System (ADS)

Barazzetti, L.; Previtali, M.; Roncoroni, F.

2018-05-01

360 degree cameras capture the whole scene around a photographer in a single shot. Cheap 360 cameras are a new paradigm in photogrammetry. The camera can be pointed to any direction, and the large field of view reduces the number of photographs. This paper aims to show that accurate metric reconstructions can be achieved with affordable sensors (less than 300 euro). The camera used in this work is the Xiaomi Mijia Mi Sphere 360, which has a cost of about 300 USD (January 2018). Experiments demonstrate that millimeter-level accuracy can be obtained during the image orientation and surface reconstruction steps, in which the solution from 360° images was compared to check points measured with a total station and laser scanning point clouds. The paper will summarize some practical rules for image acquisition as well as the importance of ground control points to remove possible deformations of the network during bundle adjustment, especially for long sequences with unfavorable geometry. The generation of orthophotos from images having a 360° field of view (that captures the entire scene around the camera) is discussed. Finally, the paper illustrates some case studies where the use of a 360° camera could be a better choice than a project based on central perspective cameras. Basically, 360° cameras become very useful in the survey of long and narrow spaces, as well as interior areas like small rooms.

A transmission and scanning electron microscopic study of the saccule in five species of catfishes.

PubMed

Jenkins, D B

1979-01-01

The sacculi of five species of catfishes were studied by transmission and scanning electron microscopy. In four species, the sagitta exhibited a multifluted anterior part and a tapered posterior part; in Corydoras aeneus, however, the fluted part was absent, and a vertical component extended dorsally to terminate near the opening of the transverse canal. In all species, the otoliths had a laminar structure. An otolithic membrane was present, and hair cell bundles projected into cavities on the macular surface of the membrane. Attachments of the otolithic membrane to the neuroepithelium included short extensions of the membrane to the tallest components of the hair cell bundles of the peripheral cells and more delicate connections to the kinocilium and taller stereocilia of central cells; in addition, attachments to the microvilli of supporting cells were present. In both hair cells and supporting cells single microtubules and bundles of microtubules were present; the bundles had an orderly arrangement and were associated with cytoplasmic densities surrounding the desmosomes. The hair cells were innervated by both afferent and efferent nerve endings. Studies of the polarization of the hair cells in all species (except C. aeneus) showed that there was a single longitudinal axis that divided dorsally polarized cells from those oriented ventrally. In Doras spinosissimus and Bunocephalus bicolor, an additional line of polarization was evident in a small area in the anterior part of the macula; therefore, in these forms there was a double bipolar orientation.

Historical dynamics in ecosystem service bundles.

PubMed

Renard, Delphine; Rhemtulla, Jeanine M; Bennett, Elena M

2015-10-27

Managing multiple ecosystem services (ES), including addressing trade-offs between services and preventing ecological surprises, is among the most pressing areas for sustainability research. These challenges require ES research to go beyond the currently common approach of snapshot studies limited to one or two services at a single point in time. We used a spatiotemporal approach to examine changes in nine ES and their relationships from 1971 to 2006 across 131 municipalities in a mixed-use landscape in Quebec, Canada. We show how an approach that incorporates time and space can improve our understanding of ES dynamics. We found an increase in the provision of most services through time; however, provision of ES was not uniformly enhanced at all locations. Instead, each municipality specialized in providing a bundle (set of positively correlated ES) dominated by just a few services. The trajectory of bundle formation was related to changes in agricultural policy and global trends; local biophysical and socioeconomic characteristics explained the bundles' increasing spatial clustering. Relationships between services varied through time, with some provisioning and cultural services shifting from a trade-off or no relationship in 1971 to an apparent synergistic relationship by 2006. By implementing a spatiotemporal perspective on multiple services, we provide clear evidence of the dynamic nature of ES interactions and contribute to identifying processes and drivers behind these changing relationships. Our study raises questions about using snapshots of ES provision at a single point in time to build our understanding of ES relationships in complex and dynamic social-ecological systems.

Self-Assembled CNT-Polymer Hybrids in Single-Walled Carbon Nanotubes Dispersed Aqueous Triblock Copolymer Solutions

NASA Astrophysics Data System (ADS)

Vijayaraghavan, D.; Manjunatha, A. S.; Poojitha, C. G.

2018-04-01

We have carried out scanning electron microscopy (SEM), differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), electrical conductivity, and 1H NMR studies as a function of temperature on single-walled carbon nanotubes (SWCNTs) dispersed aqueous triblock copolymer (P123) solutions. The single-walled carbon nanotubes in this system aggregate to form bundles, and the bundles aggregate to form net-like structures. Depending on the temperature and phases of the polymer, this system exhibits three different self-assembled CNT-polymer hybrids. We find CNT-unimer hybrid at low temperatures, CNT-micelle hybrid at intermediate temperatures wherein the polymer micelles are adsorbed in the pores of the CNT nets, and another type of CNT-micelle hybrid at high temperatures wherein the polymer micelles are adsorbed on the surface of the CNT bundles. Our DSC thermogram showed two peaks related to these structural changes in the CNT-polymer hybrids. Temperature dependence of the 1H NMR chemical shifts of the molecular groups of the polymer and the AC electrical conductivity of the composite also showed discontinuous changes at the temperatures at which the CNT-polymer hybrid's structural changes are seen. Interestingly, for a higher CNT concentration (0.5 wt.%) in the system, the aggregated polymer micelles adsorbed on the CNTs exhibit cone-like and cube-like morphologies at the intermediate and at high temperatures respectively.

Digital image correlation-aided mechanical characterization of the anteromedial and posterolateral bundles of the anterior cruciate ligament.

PubMed

Mallett, Kaitlyn F; Arruda, Ellen M

2017-07-01

The anterior cruciate ligament (ACL) is one of the most commonly injured soft tissue structures in the articular knee joint, often requiring invasive surgery for patients to restore pre-injury knee kinematics. There is a pressing need to understand the role of the ACL in knee function, in order to select proper replacements. Digital image correlation (DIC), a non-contact full field displacement measurement technique, is an established tool for evaluating non-biological materials. The application of DIC to soft tissues has been in the nascent stages, largely due to patterning challenges of such materials. The ACL is notoriously difficult to mechanically characterize, due to the complex geometry of its two bundles and their insertions. This paper examines the use of DIC to determine the tensile mechanical properties of the AM and PL bundles of ovine ACLs in a well-known loading state. Homogenous loading in the mid-substance of the bundles provides for accurate development of stress/strain curves using DIC. Animal to animal variability is reduced, and the bundles are stiffer than previously thought when tissue-level strains are accurately measured. The anterior cruciate ligament (ACL), a major stabilizing ligament of the articular knee joint, is one of the most commonly injured soft tissue structures in the knee. Often, invasive surgery is required to restore pre-injury knee kinematics, and there are several long-term consequences of ACL reconstructions, including early-onset osteoarthritis. The role of the ACL in knee stability and motion has received much attention in the biomechanics community. This paper examines the use of a non-contact full-field displacement measurement technique, digital image correlation, to determine the tensile mechanical properties of the ACL. The focus of this work is to investigate the intrinsic mechanical properties of the ACL, as new knowledge in these areas will aid clinicians in selecting ACL replacements. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Adsorption in single-walled carbon nanotubes by experiments and molecular simulation II: Effect of morphology and temperature on organic adsorption

USGS Publications Warehouse

Agnihotri, S.; Rostam-Abadi, M.; Mota, J.P.B.; Rood, M.J.

2005-01-01

Hexane adsorption on single-walled carbon nanotube (SWNT) bundles was studied. Hexane adsorption capacities of two purified SWNT samples was gravimetrically determined at isothermal conditions of 25??, 37??, and 50??C for 10-4 < p/po < 0.9, where p/po is hexane vapor pressure relative to its saturation pressure. Simulation of hexane adsorption under similar temperature and pressure conditions were performed on the external and internal sites of nanotube bundles of diameters same as those in experimental samples. The simulations could predict isotherms for a hypothetical scenario where all nanotubes in a sample would be open. This is an abstract of a paper presented at the AIChE Annual Meeting and Fall Showcase (Cincinnati, OH 10/30/2005-11/4/2005).

Hexabundles: first results

NASA Astrophysics Data System (ADS)

Bryant, Julia J.; O'Byrne, John W.; Bland-Hawthorn, Joss; Leon-Saval, Sergio G.

2010-07-01

New multi-core imaging fibre bundles - hexabundles - being developed at the University of Sydney will provide simultaneous integral field spectroscopy for hundreds of celestial sources across a wide angular field. These are a natural progression from the use of single fibres in existing galaxy surveys. Hexabundles will allow us to address fundamental questions in astronomy without the biases introduced by a fixed entrance aperture. We have begun to consider instrument concepts that exploit hundreds of hexabundles over the widest possible field of view. To this end, we have characterised the performance of a 61-core fully fused hexabundle and 5 unfused bundles with 7 cores each. All fibres in bundles have 100 micron cores. In the fused bundle, the cores are distorted from a circular shape in order to achieve a higher fill fraction. The unfused bundles have circular cores and five different cladding thicknesses which affect the fill fraction. We compare the optical performance of all 6 bundles and find that the advantage of smaller interstitial holes (higher fill fraction) is outweighed by the increase in FRD, crosstalk and the poor optical performance caused by the deformation of the fibre cores. Uniformly high throughput and low cross-talk are essential for imaging faint astronomical targets with sufficient resolution to disentangle the dynamical structure. Devices already under development will have 100-200 unfused cores, although larger formats are feasible. The light-weight packaging of hexabundles is sufficiently flexible to allow existing robotic positioners to make use of them.

Mid-infrared chalcogenide fiber devices for medical applications

NASA Astrophysics Data System (ADS)

Chenard, Francois; Alvarez, Oseas; Buff, Andrew

2018-02-01

High-purity chalcogenide glasses and fiber draw processes enable the production of state-of-the-art mid-infrared fibers for 1.5 to 10 micron transmission. Multimode and single-mode mid-infrared fibers are produced with low-loss (<0.2 dB/m), high tensile strength (>25 kpsi), and high power laser handling capability (>11.8 MW/cm2). Chalcogenide fibers support the development of cutting-edge devices for mid-infrared medical applications. Connectorized cables transmit laser power to a sample or mid-infrared radiation to a detector. Broadband antireflection microstructures are thermally stamped on the chalcogenide fiber tip to reduce the surface reflection from 17% to <5%. Also custom fiber-optic probe bundles are made with multiple fiber legs (source, sample, signal) for reflection and backscatter spectroscopy measurement. For example, a 7 x 1 fiber probe bundle is presented. Additionally imaging fiber bundle is made to perform remote thermal and spectral imaging. Square preforms are drawn, stacked, squared and fused multiple times to produce a 64 x 64 imaging fiber bundle with fiber pixel size of 34 microns and the numerical aperture of 0.3. The 2- meter long imaging fiber bundle is small (2.2 mm x 2.2 mm), flexible (bend radius >10 mm) and transmits over the spectral range of 1.5 to 6.5 micron.

Stiff muscle fibers in calf muscles of patients with cerebral palsy lead to high passive muscle stiffness.

PubMed

Mathewson, Margie A; Chambers, Henry G; Girard, Paul J; Tenenhaus, Mayer; Schwartz, Alexandra K; Lieber, Richard L

2014-12-01

Cerebral palsy (CP), caused by an injury to the developing brain, can lead to alterations in muscle function. Subsequently, increased muscle stiffness and decreased joint range of motion are often seen in patients with CP. We examined mechanical and biochemical properties of the gastrocnemius and soleus muscles, which are involved in equinus muscle contracture. Passive mechanical testing of single muscle fibers from gastrocnemius and soleus muscle of patients with CP undergoing surgery for equinus deformity showed a significant increase in fiber stiffness (p<0.01). Bundles of fibers that included their surrounding connective tissues showed no stiffness difference (p=0.28).). When in vivo sarcomere lengths were measured and fiber and bundle stiffness compared at these lengths, both fibers and bundles of patients with CP were predicted to be much stiffer in vivo compared to typically developing (TD) individuals. Interestingly, differences in fiber and bundle stiffness were not explained by typical biochemical measures such as titin molecular weight (a giant protein thought to impact fiber stiffness) or collagen content (a proxy for extracellular matrix amount). We suggest that the passive mechanical properties of fibers and bundles are thus poorly understood. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Variable recruitment fluidic artificial muscles: modeling and experiments

NASA Astrophysics Data System (ADS)

Bryant, Matthew; Meller, Michael A.; Garcia, Ephrahim

2014-07-01

We investigate taking advantage of the lightweight, compliant nature of fluidic artificial muscles to create variable recruitment actuators in the form of artificial muscle bundles. Several actuator elements at different diameter scales are packaged to act as a single actuator device. The actuator elements of the bundle can be connected to the fluidic control circuit so that different groups of actuator elements, much like individual muscle fibers, can be activated independently depending on the required force output and motion. This novel actuation concept allows us to save energy by effectively impedance matching the active size of the actuators on the fly based on the instantaneous required load. This design also allows a single bundled actuator to operate in substantially different force regimes, which could be valuable for robots that need to perform a wide variety of tasks and interact safely with humans. This paper proposes, models and analyzes the actuation efficiency of this actuator concept. The analysis shows that variable recruitment operation can create an actuator that reduces throttling valve losses to operate more efficiently over a broader range of its force-strain operating space. We also present preliminary results of the design, fabrication and experimental characterization of three such bioinspired variable recruitment actuator prototypes.

Active Coupled Oscillators in the Inner Ear

NASA Astrophysics Data System (ADS)

Strimbu, Clark Elliott

Auditory and vestibular systems are endowed with an active process that enables them to detect signals as small as a few Angstroms; they also exhibit frequency selectivity; show strong nonlinearities; and can exhibit as spontaneous activity. Much of this active process comes from the sensory hair cells at the periphery of the auditory and vestibular systems. Each hair cell is capped by an eponymous hair bundle, a specialized structure that transduces mechanical forces into electrical signals. Experiments on mechanically decoupled cells from the frog sacculus have shown that individual hair bundles behave in an active manner analogous to an intact organ suggesting a common cellular basis for the active processes seen in many species. In particular, mechanically decoupled hair bundles show rapid active movements in response to transient stimuli and exhibit spontaneous oscillations. However, a single mechanosensitive hair cell is unable to match the performance of an entire organ. In vivo, hair bundles are often coupled to overlying membranes, gelatinous extracellular matrices. We used an in vitro preparation of the frog sacculus in which the otolithic membrane has been left intact. Under natural coupling conditions, there is a strong degree of correlation across the saccular epithelium, suggesting that the collective response of many cells contributes to the extreme sensitivity of this organ. When the membrane is left intact, the hair bundles do not oscillate spontaneously, showing that the natural coupling and loading tunes them into a quiescent regime. However, when stimulated by a pulse, the bundles show a rapid biphasic response that is abolished when the transduction channels are blocked. The active forces generated by the bundles are sufficient to move the overlying membrane.

Direct electrical and mechanical characterization of in situ generated DNA between the tips of silicon nanotweezers (SNT).

PubMed

Karsten, Stanislav L; Kumemura, Momoko; Jalabert, Laurent; Lafitte, Nicolas; Kudo, Lili C; Collard, Dominique; Fujita, Hiroyuki

2016-05-24

Previously, we reported the application of micromachined silicon nanotweezers (SNT) integrated with a comb-drive actuator and capacitive sensors for capturing and mechanical characterization of DNA bundles. Here, we demonstrate direct DNA amplification on such a MEMS structure with subsequent electrical and mechanical characterization of a single stranded DNA (ssDNA) bundle generated between the tips of SNT via isothermal rolling circle amplification (RCA) and dielectrophoresis (DEP). An in situ generated ssDNA bundle was visualized and evaluated via electrical conductivity (I-V) and mechanical frequency response measurements. Colloidal gold nanoparticles significantly enhanced (P < 0.01) the electrical properties of thin ssDNA bundles. The proposed technology allows direct in situ synthesis of DNA with a predefined sequence on the tips of a MEMS sensor device, such as SNT, followed by direct DNA electrical and mechanical characterization. In addition, our data provides a "proof-of-principle" for the feasibility of the on-chip label free DNA detection device that can be used for a variety of biomedical applications focused on sequence specific DNA detection.

How to Pay for Health Care.

PubMed

Porter, Michael E; Kaplan, Robert S

2016-01-01

The United States stands at a crossroads in how to pay for health care. Fee for service, the dominant payment model in the U.S. and many other countries, is now widely recognized as perhaps the single biggest obstacle to improving health care delivery. A battle is currently raging, outside of the public eye, between the advocates of two radically different payment approaches: capitation and bundled payments. The stakes are high, and the outcome will define the shape of the health care system for many years to come, for better or for worse. In this article, the authors argue that although capitation may deliver modest savings in the short run, it brings significant risks and will fail to fundamentally change the trajectory of a broken system. The bundled payment model, in contrast, triggers competition between providers to create value where it matters--at the individual patient level--and puts health care on the right path. The authors provide robust proof-of-concept examples of bundled payment initiatives in the U.S. and abroad, address the challenges of transitioning to bundled payments, and respond to critics' concerns about obstacles to implementation.

Structural basis of filopodia formation induced by the IRSp53/MIM homology domain of human IRSp53

PubMed Central

Millard, Thomas H; Bompard, Guillaume; Heung, Man Yeung; Dafforn, Timothy R; Scott, David J; Machesky, Laura M; Fütterer, Klaus

2005-01-01

The scaffolding protein insulin receptor tyrosine kinase substrate p53 (IRSp53), a ubiquitous regulator of the actin cytoskeleton, mediates filopodia formation under the control of Rho-family GTPases. IRSp53 comprises a central SH3 domain, which binds to proline-rich regions of a wide range of actin regulators, and a conserved N-terminal IRSp53/MIM homology domain (IMD) that harbours F-actin-bundling activity. Here, we present the crystal structure of this novel actin-bundling domain revealing a coiled-coil domain that self-associates into a 180 Å-long zeppelin-shaped dimer. Sedimentation velocity experiments confirm the presence of a single molecular species of twice the molecular weight of the monomer in solution. Mutagenesis of conserved basic residues at the extreme ends of the dimer abrogated actin bundling in vitro and filopodia formation in vivo, demonstrating that IMD-mediated actin bundling is required for IRSp53-induced filopodia formation. This study promotes an expanded view of IRSp53 as an actin regulator that integrates scaffolding and effector functions. PMID:15635447

Three-dimensional Architecture of Hair-bundle Linkages Revealed by Electron-microscopic Tomography

PubMed Central

Auer, Manfred; Koster, Abrahram J.; Ziese, Ulrike; Bajaj, Chandrajit; Volkmann, Niels; Wang, Da Neng

2008-01-01

The senses of hearing and balance rest upon mechanoelectrical transduction by the hair bundles of hair cells in the inner ear. Located at the apical cellular surface, each hair bundle comprises several tens of stereocilia and a single kinocilium that are interconnected by extracellular proteinaceous links. Using electron-microscopic tomography of bullfrog saccular sensory epithelia, we examined the three-dimensional structures of basal links, kinociliary links, and tip links. We observed significant differences in the appearances and dimensions of these three structures and found two distinct populations of tip links suggestive of the involvement of different proteins, splice variants, or protein–protein interactions. We noted auxiliary links connecting the upper portions of tip links to the taller stereocilia. Tip links and auxiliary links show a tendency to adopt a globular conformation when disconnected from the membrane surface. PMID:18421501

A nano-microstructured artificial-hair-cell-type sensor based on topologically graded 3D carbon nanotube bundles

NASA Astrophysics Data System (ADS)

Yilmazoglu, O.; Yadav, S.; Cicek, D.; Schneider, J. J.

2016-09-01

A design for a unique artificial-hair-cell-type sensor (AHCTS) based entirely on 3D-structured, vertically aligned carbon nanotube (CNT) bundles is introduced. Standard microfabrication techniques were used for the straightforward micro-nano integration of vertically aligned carbon nanotube arrays composed of low-layer multi-walled CNTs (two to six layers). The mechanical properties of the carbon nanotube bundles were intensively characterized with regard to various substrates and CNT morphology, e.g. bundle height. The CNT bundles display excellent flexibility and mechanical stability for lateral bending, showing high tear resistance. The integrated 3D CNT sensor can detect three-dimensional forces using the deflection or compression of a central CNT bundle which changes the contact resistance to the shorter neighboring bundles. The complete sensor system can be fabricated using a single chemical vapor deposition (CVD) process step. Moreover, sophisticated external contacts to the surroundings are not necessary for signal detection. No additional sensors or external bias for signal detection are required. This simplifies the miniaturization and the integration of these nanostructures for future microsystem set-ups. The new nanostructured sensor system exhibits an average sensitivity of 2100 ppm in the linear regime with the relative resistance change per micron (ppm μm-1) of the individual CNT bundle tip deflection. Furthermore, experiments have shown highly sensitive piezoresistive behavior with an electrical resistance decrease of up to ˜11% at 50 μm mechanical deflection. The detection sensitivity is as low as 1 μm of deflection, and thus highly comparable with the tactile hair sensors of insects, having typical thresholds on the order of 30-50 μm. The AHCTS can easily be adapted and applied as a flow, tactile or acceleration sensor as well as a vibration sensor. Potential applications of the latter might come up in artificial cochlear systems. In particular, the stable mechanical bending of the sensor up to 90° opens up unique application opportunities.

Digital 3D Microstructure Analysis of Concrete using X-Ray Micro Computed Tomography SkyScan 1173: A Preliminary Study

NASA Astrophysics Data System (ADS)

Latief, F. D. E.; Mohammad, I. H.; Rarasati, A. D.

2017-11-01

Digital imaging of a concrete sample using high resolution tomographic imaging by means of X-Ray Micro Computed Tomography (μ-CT) has been conducted to assess the characteristic of the sample’s structure. A standard procedure of image acquisition, reconstruction, image processing of the method using a particular scanning device i.e., the Bruker SkyScan 1173 High Energy Micro-CT are elaborated. A qualitative and a quantitative analysis were briefly performed on the sample to deliver some basic ideas of the capability of the system and the bundled software package. Calculation of total VOI volume, object volume, percent of object volume, total VOI surface, object surface, object surface/volume ratio, object surface density, structure thickness, structure separation, total porosity were conducted and analysed. This paper should serve as a brief description of how the device can produce the preferred image quality as well as the ability of the bundled software packages to help in performing qualitative and quantitative analysis.

Microfabricated particle focusing device

DOEpatents

Ravula, Surendra K.; Arrington, Christian L.; Sigman, Jennifer K.; Branch, Darren W.; Brener, Igal; Clem, Paul G.; James, Conrad D.; Hill, Martyn; Boltryk, Rosemary June

2013-04-23

A microfabricated particle focusing device comprises an acoustic portion to preconcentrate particles over large spatial dimensions into particle streams and a dielectrophoretic portion for finer particle focusing into single-file columns. The device can be used for high throughput assays for which it is necessary to isolate and investigate small bundles of particles and single particles.

Neighborhood resolved fiber orientation distributions (NRFOD) in automatic labeling of white matter fiber pathways.

PubMed

Ugurlu, Devran; Firat, Zeynep; Türe, Uğur; Unal, Gozde

2018-05-01

Accurate digital representation of major white matter bundles in the brain is an important goal in neuroscience image computing since the representations can be used for surgical planning, intra-patient longitudinal analysis and inter-subject population connectivity studies. Reconstructing desired fiber bundles generally involves manual selection of regions of interest by an expert, which is subject to user bias and fatigue, hence an automation is desirable. To that end, we first present a novel anatomical representation based on Neighborhood Resolved Fiber Orientation Distributions (NRFOD) along the fibers. The resolved fiber orientations are obtained by generalized q-sampling imaging (GQI) and a subsequent diffusion decomposition method. A fiber-to-fiber distance measure between the proposed fiber representations is then used in a density-based clustering framework to select the clusters corresponding to the major pathways of interest. In addition, neuroanatomical priors are utilized to constrain the set of candidate fibers before density-based clustering. The proposed fiber clustering approach is exemplified on automation of the reconstruction of the major fiber pathways in the brainstem: corticospinal tract (CST); medial lemniscus (ML); middle cerebellar peduncle (MCP); inferior cerebellar peduncle (ICP); superior cerebellar peduncle (SCP). Experimental results on Human Connectome Project (HCP)'s publicly available "WU-Minn 500 Subjects + MEG2 dataset" and expert evaluations demonstrate the potential of the proposed fiber clustering method in brainstem white matter structure analysis. Copyright © 2018 Elsevier B.V. All rights reserved.

Atlas-Guided Cluster Analysis of Large Tractography Datasets

PubMed Central

Ros, Christian; Güllmar, Daniel; Stenzel, Martin; Mentzel, Hans-Joachim; Reichenbach, Jürgen Rainer

2013-01-01

Diffusion Tensor Imaging (DTI) and fiber tractography are important tools to map the cerebral white matter microstructure in vivo and to model the underlying axonal pathways in the brain with three-dimensional fiber tracts. As the fast and consistent extraction of anatomically correct fiber bundles for multiple datasets is still challenging, we present a novel atlas-guided clustering framework for exploratory data analysis of large tractography datasets. The framework uses an hierarchical cluster analysis approach that exploits the inherent redundancy in large datasets to time-efficiently group fiber tracts. Structural information of a white matter atlas can be incorporated into the clustering to achieve an anatomically correct and reproducible grouping of fiber tracts. This approach facilitates not only the identification of the bundles corresponding to the classes of the atlas; it also enables the extraction of bundles that are not present in the atlas. The new technique was applied to cluster datasets of 46 healthy subjects. Prospects of automatic and anatomically correct as well as reproducible clustering are explored. Reconstructed clusters were well separated and showed good correspondence to anatomical bundles. Using the atlas-guided cluster approach, we observed consistent results across subjects with high reproducibility. In order to investigate the outlier elimination performance of the clustering algorithm, scenarios with varying amounts of noise were simulated and clustered with three different outlier elimination strategies. By exploiting the multithreading capabilities of modern multiprocessor systems in combination with novel algorithms, our toolkit clusters large datasets in a couple of minutes. Experiments were conducted to investigate the achievable speedup and to demonstrate the high performance of the clustering framework in a multiprocessing environment. PMID:24386292

Arrays of Bundles of Carbon Nanotubes as Field Emitters

NASA Technical Reports Server (NTRS)

Manohara, Harish; Bronkowski, Michael

2007-01-01

Experiments have shown that with suitable choices of critical dimensions, planar arrays of bundles of carbon nanotubes (see figure) can serve as high-current-density field emitter (cold-cathode) electron sources. Whereas some hot-cathode electron sources must be operated at supply potentials of thousands of volts, these cold-cathode sources generate comparable current densities when operated at tens of volts. Consequently, arrays of bundles of carbon nanotubes might prove useful as cold-cathode sources in miniature, lightweight electron-beam devices (e.g., nanoklystrons) soon to be developed. Prior to the experiments, all reported efforts to develop carbon-nanotube-based field-emission sources had yielded low current densities from a few hundred microamperes to a few hundred milliamperes per square centimeter. An electrostatic screening effect, in which taller nanotubes screen the shorter ones from participating in field emission, was conjectured to be what restricts the emission of electrons to such low levels. It was further conjectured that the screening effect could be reduced and thus emission levels increased by increasing the spacing between nanotubes to at least by a factor of one to two times the height of the nanotubes. While this change might increase the emission from individual nanotubes, it would decrease the number of nanotubes per unit area and thereby reduce the total possible emission current. Therefore, to maximize the area-averaged current density, it would be necessary to find an optimum combination of nanotube spacing and nanotube height. The present concept of using an array of bundles of nanotubes arises partly from the concept of optimizing the spacing and height of field emitters. It also arises partly from the idea that single nanotubes may have short lifetimes as field emitters, whereas bundles of nanotubes could afford redundancy so that the loss of a single nanotube would not significantly reduce the overall field emission.

Three-dimensional reconstruction of single-cell chromosome structure using recurrence plots.

PubMed

Hirata, Yoshito; Oda, Arisa; Ohta, Kunihiro; Aihara, Kazuyuki

2016-10-11

Single-cell analysis of the three-dimensional (3D) chromosome structure can reveal cell-to-cell variability in genome activities. Here, we propose to apply recurrence plots, a mathematical method of nonlinear time series analysis, to reconstruct the 3D chromosome structure of a single cell based on information of chromosomal contacts from genome-wide chromosome conformation capture (Hi-C) data. This recurrence plot-based reconstruction (RPR) method enables rapid reconstruction of a unique structure in single cells, even from incomplete Hi-C information.

Three-dimensional reconstruction of single-cell chromosome structure using recurrence plots

NASA Astrophysics Data System (ADS)

Hirata, Yoshito; Oda, Arisa; Ohta, Kunihiro; Aihara, Kazuyuki

2016-10-01

Single-cell analysis of the three-dimensional (3D) chromosome structure can reveal cell-to-cell variability in genome activities. Here, we propose to apply recurrence plots, a mathematical method of nonlinear time series analysis, to reconstruct the 3D chromosome structure of a single cell based on information of chromosomal contacts from genome-wide chromosome conformation capture (Hi-C) data. This recurrence plot-based reconstruction (RPR) method enables rapid reconstruction of a unique structure in single cells, even from incomplete Hi-C information.

Shaping the breast in secondary microsurgical breast reconstruction: single- vs. two-esthetic unit reconstruction.

PubMed

Gravvanis, Andreas; Smith, Roger W

2010-10-01

The esthetic outcome is dictated essentially not only by the position, size, and shape of the reconstructed breast, but also by the extra scaring involved. In the present study, we conducted a visual analog scale survey to compare the esthetic outcome in delayed autologous breast reconstruction following two different abdominal flaps inset. Twenty-five patients had their reconstruction using the Single-esthetic Unit principle and were compared with 25 patients that their breast was reconstructed using the Two-Esthetic Unit principle. Photographic images were formulated to a PowerPoint presentation and cosmetic outcomes were assessed from 30 physicians, by means of a Questionnaire and a visual analog scale. Our data showed that the single-esthetic unit breast reconstruction presents significant advantages over the traditional two-esthetic units, due to inconspicuous flap reconstruction, better position of the inframammary fold, and more natural transition from native and reconstructed tissues. Moreover, patient self-evaluation of esthetic outcome and quality of life showed that single-esthetic unit reconstruction is associated with higher patient satisfaction, therefore should be considered the method of choice. © 2010 Wiley-Liss, Inc.

Living Bone Allotransplants Survive by Surgical Angiogenesis Alone: Development of a Novel Method of Composite Tissue Allotransplantation

PubMed Central

Larsen, Mikko; Pelzer, Michael; Friedrich, Patricia F.; Wood, Christina M.; Bishop, Allen T.

2011-01-01

Background: Segmental bone defects pose reconstructive challenges. Composite tissue allotransplantation offers a potential solution but requires long-term immunosuppression with attendant health risks. This study demonstrates a novel method of composite-tissue allotransplantation, permitting long-term drug-free survival, with use of therapeutic angiogenesis of autogenous vessels to maintain circulation. Methods: Ninety-three rats underwent femoral allotransplantation, isotransplantation, or allografting. Group-1 femora were transplanted across a major histocompatibility complex barrier, with microsurgical pedicle anastomoses. The contralateral saphenous artery and vein (termed the AV bundle) of the recipient animal were implanted within the medullary canal to allow development of an autogenous circulation. In Group 2, allotransplantation was also performed, but with AV bundle ligation. Group 3 bones were frozen allografts rather than composite-tissue allotransplantation femora, and Group 4 bones were isotransplants. Paired comparison allowed evaluation of AV bundle effect, bone allogenicity (isogeneic or allogeneic), and initial circulation and viability (allotransplant versus allograft). Two weeks of immunosuppression therapy maintained blood flow initially, during development of a neoangiogenic autogenous blood supply from the AV bundle in patent groups. At eighteen weeks, skin grafts from donor, recipient, and third-party rats were tested for immunocompetence and donor-specific tolerance. At twenty-one weeks, bone circulation was quantified and new bone formation was measured. Results: Final circulatory status depended on both the initial viability of the graft and the successful development of neoangiogenic circulation. Median cortical blood flow was highest in Group 1 (4.6 mL/min/100 g), intermediate in Group 4 isotransplants (0.4 mL/min/100 g), and absent in others. Capillary proliferation and new bone formation were generally highest in allotransplants (15.0%, 6.4 μm3/μm2/yr) and isotransplants with patent AV bundles (16.6%, 50.3 μm3/μm2/yr) and less in allotransplants with ligated AV bundles (4.4%, 0.0 μm3/μm2/yr) or allografts (8.1%, 24.1 μm3/μm2/yr). Donor and third-party-type skin grafts were rejected, indicating immunocompetence without donor-specific tolerance. Conclusions: In the rat model, microvascular allogeneic bone transplantation in combination with short-term immunosuppression and AV bundle implantation creates an autogenous neoangiogenic circulation, permitting long-term allotransplant survival with measurable blood flow. Clinical Relevance: These methods may allow future composite-tissue allotransplantation of bone without the appreciable health risks that are associated with long-term immunosuppression or immune tolerance induction. PMID:21266640

3D Lunar Terrain Reconstruction from Apollo Images

NASA Technical Reports Server (NTRS)

Broxton, Michael J.; Nefian, Ara V.; Moratto, Zachary; Kim, Taemin; Lundy, Michael; Segal, Alkeksandr V.

2009-01-01

Generating accurate three dimensional planetary models is becoming increasingly important as NASA plans manned missions to return to the Moon in the next decade. This paper describes a 3D surface reconstruction system called the Ames Stereo Pipeline that is designed to produce such models automatically by processing orbital stereo imagery. We discuss two important core aspects of this system: (1) refinement of satellite station positions and pose estimates through least squares bundle adjustment; and (2) a stochastic plane fitting algorithm that generalizes the Lucas-Kanade method for optimal matching between stereo pair images.. These techniques allow us to automatically produce seamless, highly accurate digital elevation models from multiple stereo image pairs while significantly reducing the influence of image noise. Our technique is demonstrated on a set of 71 high resolution scanned images from the Apollo 15 mission

Reconstruction phases in the planar three- and four-vortex problems

NASA Astrophysics Data System (ADS)

Hernández-Garduño, Antonio; Shashikanth, Banavara N.

2018-03-01

Pure reconstruction phases—geometric and dynamic—are computed in the N-point-vortex model in the plane, for the cases N=3 and N=4 . The phases are computed relative to a metric-orthogonal connection on appropriately defined principal fiber bundles. The metric is similar to the kinetic energy metric for point masses but with the masses replaced by vortex strengths. The geometric phases are shown to be proportional to areas enclosed by the closed orbit on the symmetry reduced spaces. More interestingly, simple formulae are obtained for the dynamic phases, analogous to Montgomery’s result for the free rigid body, which show them to be proportional to the time period of the symmetry reduced closed orbits. For the case N = 3 a non-zero total vortex strength is assumed. For the case N = 4 the vortex strengths are assumed equal.

Change in the Pathologic Supraspinatus: A Three-Dimensional Model of Fiber Bundle Architecture within Anterior and Posterior Regions

PubMed Central

Kim, Soo Y.; Sachdeva, Rohit; Li, Zi; Rosser, Benjamin W. C.

2015-01-01

Supraspinatus tendon tears are common and lead to changes in the muscle architecture. To date, these changes have not been investigated for the distinct regions and parts of the pathologic supraspinatus. The purpose of this study was to create a novel three-dimensional (3D) model of the muscle architecture throughout the supraspinatus and to compare the architecture between muscle regions and parts in relation to tear severity. Twelve cadaveric specimens with varying degrees of tendon tears were used. Three-dimensional coordinates of fiber bundles were collected in situ using serial dissection and digitization. Data were reconstructed and modeled in 3D using Maya. Fiber bundle length (FBL) and pennation angle (PA) were computed and analyzed. FBL was significantly shorter in specimens with large retracted tears compared to smaller tears, with the deeper fibers being significantly shorter than other parts in the anterior region. PA was significantly greater in specimens with large retracted tears, with the superficial fibers often demonstrating the largest PA. The posterior region was absent in two specimens with extensive tears. Architectural changes associated with tendon tears affect the regions and varying depths of supraspinatus differently. The results provide important insights on residual function of the pathologic muscle, and the 3D model includes detailed data that can be used in future modeling studies. PMID:26413533

Chemisorption and Diffusion of H on a Graphene Sheet and Single-Wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Srivastava, Deepak; Dzegilenko, Fedor; Menon, Madhu

2000-01-01

Recent experiments on hydrogen storage in single wall nanotubes and nanotube bundles have reported large fractional weight of stored molecular hydrogen which are not in agreement with theoretical estimates based of simulation of hydrogen storage by physisorption mechanisms. Hydrogen storage in catalytically doped nanotube bundles indicate that atomic H might undergo chemisorption changing the basic nature of the storage mechanism under investigation by many groups. Using a generalized tight-binding molecular dynamics (GTBMD) method for reactive C-H dynamics, we investigate chemisorption and diffusion of atomic H on graphene sheet and C nanotubes. Effective potential energy surfaces (EPS) for chemisorption and diffusion are calculated for graphene sheet and nanotubes of different curvatures. Analysis of the activation barriers and quantum rate constants, computed via wave-packet dynamics method, will be discussed in this presentation.

Online evolution reconstruction from a single measurement record with random time intervals for quantum communication

NASA Astrophysics Data System (ADS)

Zhou, Hua; Su, Yang; Wang, Rong; Zhu, Yong; Shen, Huiping; Pu, Tao; Wu, Chuanxin; Zhao, Jiyong; Zhang, Baofu; Xu, Zhiyong

2017-10-01

Online reconstruction of a time-variant quantum state from the encoding/decoding results of quantum communication is addressed by developing a method of evolution reconstruction from a single measurement record with random time intervals. A time-variant two-dimensional state is reconstructed on the basis of recovering its expectation value functions of three nonorthogonal projectors from a random single measurement record, which is composed from the discarded qubits of the six-state protocol. The simulated results prove that our method is robust to typical metro quantum channels. Our work extends the Fourier-based method of evolution reconstruction from the version for a regular single measurement record with equal time intervals to a unified one, which can be applied to arbitrary single measurement records. The proposed protocol of evolution reconstruction runs concurrently with the one of quantum communication, which can facilitate the online quantum tomography.

Single-stage autologous ear reconstruction for microtia.

PubMed

Kasrai, Leila; Snyder-Warwick, Alison K; Fisher, David M

2014-03-01

The authors have been using the Nagata technique since 2002. In this review of 100 consecutive ear reconstructions, the authors present technique modifications that have evolved over this period that have contributed to improved auricular contour and that now allow for auricular reconstruction in a single stage. This study is a retrospective review of a prospectively acquired database. The series is restricted to primary reconstructions performed for congenital microtia. Photographs of 10 consecutive patients are presented to demonstrate the results of the technique. Surgical complication rates are discussed. One hundred ear reconstructions were performed in 96 patients. There were 75 primary cases of congenital microtia. Twenty-four ears underwent a two-stage reconstruction, and 51 ears were reconstructed with a Nagata stage I procedure or a single-stage reconstruction. There was a gradual shift in technique, with a trend to perform fewer Nagata stage II outsetting procedures and more single-stage reconstructions. In patients who underwent an ear reconstruction in two stages, the surgical complication rate was 22 percent. In the last 40 consecutive ear reconstructions since abandoning the two-stage approach, the surgical complication rate is now 15 percent. A modification of Nagata's technique of autologous ear reconstruction for microtia is described. Modifications of the three-dimensional framework address the contour of the inferior crus and control tragal projection and position. Inclusion of a projection block and recruitment of retroauricular skin allow for symmetric projection of the ear in a single stage. Therapeutic, IV.

The Posterior Bundle's Effect on Posteromedial Elbow Instability After a Transverse Coronoid Fracture: A Biomechanical Study.

PubMed

Shukla, Dave R; Golan, Elan; Weiser, Mitch C; Nasser, Philip; Choueka, Jack; Hausman, Michael

2018-04-01

There has been increased interest in the role of the posterior bundle of the medial collateral ligament (pMUCL) in the elbow, particularly its effects on posteromedial rotatory stability. The ligament's effect in the context of an unfixable coronoid fracture has not been the focus of any study. The purposes of this biomechanical study were to evaluate the stabilizing effect of the pMUCL with a transverse coronoid fracture and to assess the effect of graft reconstruction of the ligament. We simulated a varus and internal rotatory subluxation in 7 cadaveric elbows at 30°, 60°, and 90° elbow flexion. The amount of ulnar rotation and medial ulnohumeral joint gapping were assessed in the intact elbow after we created a transverse coronoid injury, after we divided the pMUCL, and finally, after we performed a graft reconstruction of the pMUCL. At all angles tested, some stability was lost after cutting the pMUCL once the coronoid had been injured, because mean proximal ulnohumeral joint gapping increased afterward by 2.1, 2.2, and 1.3 mm at 90°, 60°, and 30°, respectively. Ulnar internal rotation significantly increased after pMUCL transection at 90°. At 60° and 30° elbow flexion, ulnar rotation increased after resection of the coronoid but not after pMUCL resection. An uninjured pMUCL stabilizes against varus internal rotatory instability in the setting of a transverse coronoid fracture at higher flexion angles. Further research is needed to optimize graft reconstruction of the pMUCL. The pMUCL is an important secondary stabilizer against posteromedial instability in the coronoid-deficient elbow. In the setting of an unfixable coronoid fracture, the surgeon should examine for posteromedial instability and consider addressing the pMUCL surgically. Copyright © 2018 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

The role of fibers in the femoral attachment of the anterior cruciate ligament in resisting tibial displacement.

PubMed

Kawaguchi, Yasuyuki; Kondo, Eiji; Takeda, Ryo; Akita, Keiichi; Yasuda, Kazunori; Amis, Andrew A

2015-03-01

The purpose was to clarify the load-bearing functions of the fibers of the femoral anterior cruciate ligament (ACL) attachment in resisting tibial anterior drawer and rotation. A sequential cutting study was performed on 8 fresh-frozen human knees. The femoral attachment of the ACL was divided into a central area that had dense fibers inserting directly into the femur and anterior and posterior fan-like extension areas. The ACL fibers were cut sequentially from the bone: the posterior fan-like area in 2 stages, the central dense area in 4 stages, and then the anterior fan-like area in 2 stages. Each knee was mounted in a robotic joint testing system that applied tibial anteroposterior 6-mm translations and 10° or 15° of internal rotation at 0° to 90° of flexion. The reduction of restraining force or moment was measured after each cut. The central area resisted 82% to 90% of the anterior drawer force; the anterior fan-like area, 2% to 3%; and the posterior fan-like area, 11% to 15%. Among the 4 central areas, most load was carried close to the roof of the intercondylar notch: the anteromedial bundle resisted 66% to 84% of the force and the posterolateral bundle resisted 16% to 9% from 0° to 90° of flexion. There was no clear pattern for tibial internal rotation, with the load shared among the posterodistal and central areas near extension and mostly the central areas in flexion. Under the experimental conditions described, 66% to 84% of the resistance to tibial anterior drawer arose from the ACL fibers at the central-proximal area of the femoral attachment, corresponding to the anteromedial bundle; the fan-like extension fibers contributed very little. This work did not support moving a single-bundle ACL graft to the side wall of the notch or attempting to cover the whole attachment area if the intention was to mimic how the natural ACL resists tibial displacements. There is ongoing debate about how best to reconstruct the ACL to restore normal knee function, including where is the best place for ACL graft tunnels. This study found that the most important area on the femur, in terms of resisting displacement of the tibia, was in the central-anterior part of the femoral ACL attachment, near the roof of the intercondylar notch. The testing protocol did not lead to data that would support using a large ACL graft tunnel that attempts to cover the whole natural femoral attachment area. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

The Role of Fibers in the Femoral Attachment of the Anterior Cruciate Ligament in Resisting Tibial Displacement

PubMed Central

Kawaguchi, Yasuyuki; Kondo, Eiji; Takeda, Ryo; Akita, Keiichi; Yasuda, Kazunori; Amis, Andrew A.

2015-01-01

Purpose The purpose was to clarify the load-bearing functions of the fibers of the femoral anterior cruciate ligament (ACL) attachment in resisting tibial anterior drawer and rotation. Methods A sequential cutting study was performed on 8 fresh-frozen human knees. The femoral attachment of the ACL was divided into a central area that had dense fibers inserting directly into the femur and anterior and posterior fan-like extension areas. The ACL fibers were cut sequentially from the bone: the posterior fan-like area in 2 stages, the central dense area in 4 stages, and then the anterior fan-like area in 2 stages. Each knee was mounted in a robotic joint testing system that applied tibial anteroposterior 6-mm translations and 10° or 15° of internal rotation at 0° to 90° of flexion. The reduction of restraining force or moment was measured after each cut. Results The central area resisted 82% to 90% of the anterior drawer force; the anterior fan-like area, 2% to 3%; and the posterior fan-like area, 11% to 15%. Among the 4 central areas, most load was carried close to the roof of the intercondylar notch: the anteromedial bundle resisted 66% to 84% of the force and the posterolateral bundle resisted 16% to 9% from 0° to 90° of flexion. There was no clear pattern for tibial internal rotation, with the load shared among the posterodistal and central areas near extension and mostly the central areas in flexion. Conclusions Under the experimental conditions described, 66% to 84% of the resistance to tibial anterior drawer arose from the ACL fibers at the central-proximal area of the femoral attachment, corresponding to the anteromedial bundle; the fan-like extension fibers contributed very little. This work did not support moving a single-bundle ACL graft to the side wall of the notch or attempting to cover the whole attachment area if the intention was to mimic how the natural ACL resists tibial displacements. Clinical Relevance There is ongoing debate about how best to reconstruct the ACL to restore normal knee function, including where is the best place for ACL graft tunnels. This study found that the most important area on the femur, in terms of resisting displacement of the tibia, was in the central-anterior part of the femoral ACL attachment, near the roof of the intercondylar notch. The testing protocol did not lead to data that would support using a large ACL graft tunnel that attempts to cover the whole natural femoral attachment area. PMID:25530509

A Method for 3D-Reconstruction of a Muscle Thick Filament Using the Tilt Series Images of a Single Filament Electron Tomogram

PubMed Central

Márquez, G.; Pinto, A.; Alamo, L.; Baumann, B.; Ye, F.; Winkler, H.; Taylor, K.; Padrón, R.

2014-01-01

Summary Myosin interacting-heads (MIH) motifs are visualized in 3D-reconstructions of thick filaments from striated muscle. These reconstructions are calculated by averaging methods using images from electron micrographs of grids prepared using numerous filament preparations. Here we propose an alternative method to calculate the 3D-reconstruction of a single thick filament using only a tilt series images recorded by electron tomography. Relaxed thick filaments, prepared from tarantula leg muscle homogenates, were negatively stained. Single-axis tilt series of single isolated thick filaments were obtained with the electron microscope at a low electron dose, and recorded on a CCD camera by electron tomography. An IHRSR 3D-recontruction was calculated from the tilt series images of a single thick filament. The reconstruction was enhanced by including in the search stage dual tilt image segments while only single tilt along the filament axis is usually used, as well as applying a band pass filter just before the back projection. The reconstruction from a single filament has a 40 Å resolution and clearly shows the presence of MIH motifs. In contrast, the electron tomogram 3D-reconstruction of the same thick filament –calculated without any image averaging and/or imposition of helical symmetry- only reveals MIH motifs infrequently. This is –to our knowledge- the first application of the IHRSR method to calculate a 3D reconstruction from tilt series images. This single filament IHRSR reconstruction method (SF-IHRSR) should provide a new tool to assess structural differences between well-ordered thick (or thin) filaments in a grid by recording separately their electron tomograms. PMID:24727133

A method for 3D-reconstruction of a muscle thick filament using the tilt series images of a single filament electron tomogram.

PubMed

Márquez, G; Pinto, A; Alamo, L; Baumann, B; Ye, F; Winkler, H; Taylor, K; Padrón, R

2014-05-01

Myosin interacting-heads (MIH) motifs are visualized in 3D-reconstructions of thick filaments from striated muscle. These reconstructions are calculated by averaging methods using images from electron micrographs of grids prepared using numerous filament preparations. Here we propose an alternative method to calculate the 3D-reconstruction of a single thick filament using only a tilt series images recorded by electron tomography. Relaxed thick filaments, prepared from tarantula leg muscle homogenates, were negatively stained. Single-axis tilt series of single isolated thick filaments were obtained with the electron microscope at a low electron dose, and recorded on a CCD camera by electron tomography. An IHRSR 3D-recontruction was calculated from the tilt series images of a single thick filament. The reconstruction was enhanced by including in the search stage dual tilt image segments while only single tilt along the filament axis is usually used, as well as applying a band pass filter just before the back projection. The reconstruction from a single filament has a 40 Å resolution and clearly shows the presence of MIH motifs. In contrast, the electron tomogram 3D-reconstruction of the same thick filament - calculated without any image averaging and/or imposition of helical symmetry - only reveals MIH motifs infrequently. This is - to our knowledge - the first application of the IHRSR method to calculate a 3D reconstruction from tilt series images. This single filament IHRSR reconstruction method (SF-IHRSR) should provide a new tool to assess structural differences between well-ordered thick (or thin) filaments in a grid by recording separately their electron tomograms. Copyright © 2014 Elsevier Inc. All rights reserved.

G2-structures for N  =  1 supersymmetric AdS4 solutions of M-theory

NASA Astrophysics Data System (ADS)

Grigorian, Sergey

2018-04-01

We study the N  =  1 supersymmetric solutions of D  =  11 supergravity obtained as a warped product of four-dimensional anti-de Sitter space with a seven-dimensional Riemannian manifold M. Using the octonion bundle structure on M we reformulate the Killing spinor equations in terms of sections of the octonion bundle on M. The solutions then define a single complexified G 2-structure on M or equivalently two real G 2-structures. We then study the torsion of these G 2-structures and the relationships between them.

Incremental Multi-view 3D Reconstruction Starting from Two Images Taken by a Stereo Pair of Cameras

NASA Astrophysics Data System (ADS)

El hazzat, Soulaiman; Saaidi, Abderrahim; Karam, Antoine; Satori, Khalid

2015-03-01

In this paper, we present a new method for multi-view 3D reconstruction based on the use of a binocular stereo vision system constituted of two unattached cameras to initialize the reconstruction process. Afterwards , the second camera of stereo vision system (characterized by varying parameters) moves to capture more images at different times which are used to obtain an almost complete 3D reconstruction. The first two projection matrices are estimated by using a 3D pattern with known properties. After that, 3D scene points are recovered by triangulation of the matched interest points between these two images. The proposed approach is incremental. At each insertion of a new image, the camera projection matrix is estimated using the 3D information already calculated and new 3D points are recovered by triangulation from the result of the matching of interest points between the inserted image and the previous image. For the refinement of the new projection matrix and the new 3D points, a local bundle adjustment is performed. At first, all projection matrices are estimated, the matches between consecutive images are detected and Euclidean sparse 3D reconstruction is obtained. So, to increase the number of matches and have a more dense reconstruction, the Match propagation algorithm, more suitable for interesting movement of the camera, was applied on the pairs of consecutive images. The experimental results show the power and robustness of the proposed approach.

Comparison of Models for Spacer Grid Pressure Loss in Nuclear Fuel Bundles for One and Two-Phase Flows

NASA Astrophysics Data System (ADS)

Maskal, Alan B.

Spacer grids maintain the structural integrity of the fuel rods within fuel bundles of nuclear power plants. They can also improve flow characteristics within the nuclear reactor core. However, spacer grids add reactor coolant pressure losses, which require estimation and engineering into the design. Several mathematical models and computer codes were developed over decades to predict spacer grid pressure loss. Most models use generalized characteristics, measured by older, less precise equipment. The study of OECD/US-NRC BWR Full-Size Fine Mesh Bundle Tests (BFBT) provides updated and detailed experimental single and two-phase results, using technically advanced flow measurements for a wide range of boundary conditions. This thesis compares the predictions from the mathematical models to the BFBT experimental data by utilizing statistical formulae for accuracy and precision. This thesis also analyzes the effects of BFBT flow characteristics on spacer grids. No single model has been identified as valid for all flow conditions. However, some models' predictions perform better than others within a range of flow conditions, based on the accuracy and precision of the models' predictions. This study also demonstrates that pressure and flow quality have a significant effect on two-phase flow spacer grid models' biases.

Single microfilaments mediate the early steps of microtubule bundling during preprophase band formation in onion cotyledon epidermal cells

PubMed Central

Takeuchi, Miyuki; Karahara, Ichirou; Kajimura, Naoko; Takaoka, Akio; Murata, Kazuyoshi; Misaki, Kazuyo; Yonemura, Shigenobu; Staehelin, L. Andrew; Mineyuki, Yoshinobu

2016-01-01

The preprophase band (PPB) is a cytokinetic apparatus that determines the site of cell division in plants. It originates as a broad band of microtubules (MTs) in G2 and narrows to demarcate the future division site during late prophase. Studies with fluorescent probes have shown that PPBs contain F-actin during early stages of their development but become actin depleted in late prophase. Although this suggests that actins contribute to the early stages of PPB formation, how actins contribute to PPB-MT organization remains unsolved. To address this question, we used electron tomography to investigate the spatial relationship between microfilaments (MFs) and MTs at different stages of PPB assembly in onion cotyledon epidermal cells. We demonstrate that the PPB actins observed by fluorescence microscopy correspond to short, single MFs. A majority of the MFs are bound to MTs, with a subset forming MT-MF-MT bridging structures. During the later stages of PPB assembly, the MF-mediated links between MTs are displaced by MT-MT linkers as the PPB MT arrays mature into tightly packed MT bundles. On the basis of these observations, we propose that the primary function of actins during PPB formation is to mediate the initial bundling of the PPB MTs. PMID:27053663

Microscopic Analysis of Bacterial Motility at High Pressure

PubMed Central

Nishiyama, Masayoshi; Sowa, Yoshiyuki

2012-01-01

The bacterial flagellar motor is a molecular machine that converts an ion flux to the rotation of a helical flagellar filament. Counterclockwise rotation of the filaments allows them to join in a bundle and propel the cell forward. Loss of motility can be caused by environmental factors such as temperature, pH, and solvation. Hydrostatic pressure is also a physical inhibitor of bacterial motility, but the detailed mechanism of this inhibition is still unknown. Here, we developed a high-pressure microscope that enables us to acquire high-resolution microscopic images, regardless of applied pressures. We also characterized the pressure dependence of the motility of swimming Escherichia coli cells and the rotation of single flagellar motors. The fraction and speed of swimming cells decreased with increased pressure. At 80 MPa, all cells stopped swimming and simply diffused in solution. After the release of pressure, most cells immediately recovered their initial motility. Direct observation of the motility of single flagellar motors revealed that at 80 MPa, the motors generate torque that should be sufficient to join rotating filaments in a bundle. The discrepancy in the behavior of free swimming cells and individual motors could be due to the applied pressure inhibiting the formation of rotating filament bundles that can propel the cell body in an aqueous environment. PMID:22768943

Skeletal Muscle Fibrosis and Stiffness Increase after Rotator Cuff Tendon Injury and Neuromuscular Compromise in a Rat Model

PubMed Central

Sato, Eugene J.; Killian, Megan L.; Choi, Anthony J.; Lin, Evie; Esparza, Mary C.; Galatz, Leesa M.; Thomopoulos, Stavros; Ward, Samuel R.

2015-01-01

Rotator cuff tears can cause irreversible changes (e.g., fibrosis) to the structure and function of the injured muscle(s). Fibrosis leads to increased muscle stiffness resulting in increased tension at the rotator cuff repair site. This tension influences repairability and healing potential in the clinical setting. However, the micro- and meso-scale structural and molecular sources of these whole-muscle mechanical changes are poorly understood. Here, single muscle fiber and fiber bundle passive mechanical testing was performed on rat supraspinatus and infraspinatus muscles with experimentally induced massive rotator cuff tears (Tenotomy) as well as massive tears with chemical denervation (Tenotomy+BTX) at 8 and 16 weeks post-injury. Titin molecular weight, collagen content, and myosin heavy chain profiles were measured and correlated with mechanical variables. Single fiber stiffness was not different between controls and experimental groups. However, fiber bundle stiffness was significantly increased at 8 weeks in the Tenotomy+BTX group compared to Tenotomy or control groups. Many of the changes were resolved by 16 weeks. Only fiber bundle passive mechanics was weakly correlated with collagen content. These data suggest that tendon injury with concomitant neuromuscular compromise results in extracellular matrix production and increases in stiffness of the muscle, potentially complicating subsequent attempts for surgical repair. PMID:24838823

Co-Registration of Terrestrial and Uav-Based Images - Experimental Results

NASA Astrophysics Data System (ADS)

Gerke, M.; Nex, F.; Jende, P.

2016-03-01

For many applications within urban environments the combined use of images taken from the ground and from unmanned aerial platforms seems interesting: while from the airborne perspective the upper parts of objects including roofs can be observed, the ground images can complement the data from lateral views to retrieve a complete visualisation or 3D reconstruction of interesting areas. The automatic co-registration of air- and ground-based images is still a challenge and cannot be considered solved. The main obstacle is originating from the fact that objects are photographed from quite different angles, and hence state-of-the-art tie point measurement approaches cannot cope with the induced perspective transformation. One first important step towards a solution is to use airborne images taken under slant directions. Those oblique views not only help to connect vertical images and horizontal views but also provide image information from 3D-structures not visible from the other two directions. According to our experience, however, still a good planning and many images taken under different viewing angles are needed to support an automatic matching across all images and complete bundle block adjustment. Nevertheless, the entire process is still quite sensible - the removal of a single image might lead to a completely different or wrong solution, or separation of image blocks. In this paper we analyse the impact different parameters and strategies have on the solution. Those are a) the used tie point matcher, b) the used software for bundle adjustment. Using the data provided in the context of the ISPRS benchmark on multi-platform photogrammetry, we systematically address the mentioned influences. Concerning the tie-point matching we test the standard SIFT point extractor and descriptor, but also the SURF and ASIFT-approaches, the ORB technique, as well as (A)KAZE, which are based on a nonlinear scale space. In terms of pre-processing we analyse the Wallis-filter. Results show that in more challenging situations, in this case for data captured from different platforms at different days most approaches do not perform well. Wallis-filtering emerged to be most helpful especially for the SIFT approach. The commercial software pix4dmapper succeeds in overall bundle adjustment only for some configurations, and especially not for the entire image block provided.

Direct Hospital Cost of Outcome Pathways in Implant-Based Reconstruction with Acellular Dermal Matrices.

PubMed

Qureshi, Ali A; Broderick, Kristen; Funk, Susan; Reaven, Nancy; Tenenbaum, Marissa M; Myckatyn, Terence M

2016-08-01

Current cost data on tissue expansion followed by exchange for permanent implant (TE/I) reconstruction lack a necessary assessment of the experience of a heterogenous breast cancer patient population and their multiple outcome pathways. We extend our previous analysis to that of direct hospital cost as bundling of payments is likely to follow the changing centralization of cancer care at the hospital level. We performed a retrospective analysis (2003-2009) of TE/I reconstructions with or without an acellular dermal matrix (ADM), namely Alloderm RTM. Postreconstructive events were analyzed and organized into outcome pathways as previously described. Aggregated and normalized inpatient and outpatient hospital direct costs and physician reimbursement were generated for each outcome pathway with or without ADM. Three hundred sixty-seven patients were analyzed. The average 2-year hospital direct cost per TE/I breast reconstruction patient was $11,862 in the +ADM and $12,319 in the -ADM groups (P > 0.05). Initial reconstructions were costlier in the +ADM ($6,868) than in the -ADM ($5,615) group, but the average cost of subsequent postreconstructive events within 2 years was significantly lower in +ADM ($5,176) than -ADM ($6,704) patients (P < 0.05). When a complication occurred, but reconstruction was still completed within 2 years, greater costs were incurred in the -ADM than in the +ADM group for most scenarios, leading to a net equalization of cost between study groups. Although direct hospital cost is an important factor for resource and fund allocation, it should not remain the sole factor when deciding to use ADM in TE/I reconstruction.

Model-Based Building Detection from Low-Cost Optical Sensors Onboard Unmanned Aerial Vehicles

NASA Astrophysics Data System (ADS)

Karantzalos, K.; Koutsourakis, P.; Kalisperakis, I.; Grammatikopoulos, L.

2015-08-01

The automated and cost-effective building detection in ultra high spatial resolution is of major importance for various engineering and smart city applications. To this end, in this paper, a model-based building detection technique has been developed able to extract and reconstruct buildings from UAV aerial imagery and low-cost imaging sensors. In particular, the developed approach through advanced structure from motion, bundle adjustment and dense image matching computes a DSM and a true orthomosaic from the numerous GoPro images which are characterised by important geometric distortions and fish-eye effect. An unsupervised multi-region, graphcut segmentation and a rule-based classification is responsible for delivering the initial multi-class classification map. The DTM is then calculated based on inpaininting and mathematical morphology process. A data fusion process between the detected building from the DSM/DTM and the classification map feeds a grammar-based building reconstruction and scene building are extracted and reconstructed. Preliminary experimental results appear quite promising with the quantitative evaluation indicating detection rates at object level of 88% regarding the correctness and above 75% regarding the detection completeness.

Connectome imaging for mapping human brain pathways

PubMed Central

Shi, Y; Toga, A W

2017-01-01

With the fast advance of connectome imaging techniques, we have the opportunity of mapping the human brain pathways in vivo at unprecedented resolution. In this article we review the current developments of diffusion magnetic resonance imaging (MRI) for the reconstruction of anatomical pathways in connectome studies. We first introduce the background of diffusion MRI with an emphasis on the technical advances and challenges in state-of-the-art multi-shell acquisition schemes used in the Human Connectome Project. Characterization of the microstructural environment in the human brain is discussed from the tensor model to the general fiber orientation distribution (FOD) models that can resolve crossing fibers in each voxel of the image. Using FOD-based tractography, we describe novel methods for fiber bundle reconstruction and graph-based connectivity analysis. Building upon these novel developments, there have already been successful applications of connectome imaging techniques in reconstructing challenging brain pathways. Examples including retinofugal and brainstem pathways will be reviewed. Finally, we discuss future directions in connectome imaging and its interaction with other aspects of brain imaging research. PMID:28461700

No difference in the graft shift between a round and a rounded rectangular femoral tunnel for anterior cruciate ligament reconstruction: an experimental study.

PubMed

Takata, Yasushi; Nakase, Junsuke; Oshima, Takeshi; Shimozaki, Kengo; Asai, Kazuki; Tsuchiya, Hiroyuki

2018-05-16

We developed a novel technique of creating a rounded rectangular femoral bone tunnel for anatomical, single-bundle, autologous hamstring tendon anterior cruciate ligament (ACL) reconstruction. Although this tunnel has many advantages, its non-circular shape has raised concerns regarding excessive graft shift within the bone tunnel. This study aimed to compare the graft shift between round and rounded rectangular tunnels using a graft diameter tester for simulating the femoral bone tunnel. Seven semitendinosus tendon grafts harvested from fresh-frozen cadavers were prepared by removing all excess soft tissue. The two ends of a double-fold hamstring tendon were sutured using a baseball stitch and then looped over a TightRope (Arthrex Co., Ltd., Naples, Florida, USA) to make a fourfold graft. The diameter of the graft was standardized to 8 mm using a round graft diameter tester. A round and an original rounded rectangular graft diameter tester were used for simulating the respective femoral bone tunnels. The graft was inserted into the tunnel, with the TightRope positioned on the outside of the tunnel. The distal end of the graft was tensioned to 40 N at an angle of 75° to reproduce the most severe graft bending angle. Digital photographs of the tunnel aperture taken at each simulated tunnel and the range of graft shift in the simulated tunnel were analyzed by ImageJ software. Statistical analyses were performed using the Tukey test. P < 0.05 was considered to be significant. There were no significant differences between the round and the rounded rectangular tunnel groups (P > 0.05) in terms of graft shift, gap area, and graft shift ratio. In a simulated ACL reconstruction, there is no difference in the graft shift between a round and a rounded rectangular bone tunnel.

Rheological alteration of erythrocytes exposed to carbon nanotubes.

PubMed

Heo, Yujin; Li, Cheng-Ai; Kim, Duckjong; Shin, Sehyun

2017-01-01

Single-walled carbon nanotubes (SWNTs) have been increasingly used in a variety of biomedical applications, such as in vivo delivery of drugs and tumor imaging. Potential exposure of SWNTs to human red blood cells (RBCs) may cause serious toxicity including alteration of mechanical properties of cells. The present study investigated the cellular response to exposure of SWNTs with measuring rheological characteristics of RBCs, including hemolysis, deformability, aggregation, and morphological changes. RBCs were exposed to two different dispersion-state samples (i.e. individual SWNTs and bundled SWNTs) in chitosan hydroxyphenyl acetamide (CHPA) solutions. The concentrations of SWNTs were carefully chosen to avoid any hemorheological alterations due to hemolysis. Rheological characteristics were measured using microfluidic-laser diffractometry and aggregometry. Our results show that the bundled SWNTs had higher hemolytic activity than did the individual SWNTs. RBC aggregation apparently decreased as the concentration of SWNTs or incubation time increased. Additionally, bundled SWNTs caused significant alterations in the shape and fusion of RBCs. In conclusion, bundled SWNTs were found to be more toxic than individual SWNTs. These results provide important insights into the interactions between RBCs and SWNTs and will facilitate assessment of the risk of nanomaterial toxicity of blood.

Simultaneous photoacoustic and optically mediated ultrasound microscopy: an in vivo study

PubMed Central

Orlova, Anna; Shirmanova, Marina; Postnikova, Anna; Turchin, Ilya

2015-01-01

We propose the use of thermoelastic (TE) excitation of an ultrasonic (US) detector by backscattered laser radiation as a means of upgrading a single-modality photoacoustic (PA) microscope to dual-modality PA/US imaging at minimal cost. The upgraded scanning head of our dual-modality microscope consists of a fiber bundle with 14 output arms and a 32MHz polyvinylidene difluoride (PVDF) detector with a 34 MHz bandwidth (−6 dB level), 12.7 mm focal length, and a 0.25 numerical aperture. A single optical pulse delivered through the fiber bundle to the biotissue being investigated, in combination with a metalized surface on the PVDF detector allows us to obtain both PA and US A-scans. To demonstrate the in vivo capabilities of the proposed method we present the results of bimodal imaging of the brain of a newborn rat, a mouse tail and a mouse tumor. PMID:25780752

Optimized mode-field adapter for low-loss fused fiber bundle signal and pump combiners

NASA Astrophysics Data System (ADS)

Koška, Pavel; Baravets, Yauhen; Peterka, Pavel; Písařík, Michael; Bohata, Jan

2015-03-01

In our contribution we report novel mode field adapter incorporated inside bundled tapered pump and signal combiner. Pump and signal combiners are crucial component of contemporary double clad high power fiber lasers. Proposed combiner allows simultaneous matching to single mode core on input and output. We used advanced optimization techniques to match the combiner to a single mode core simultaneously on input and output and to minimalize losses of the combiner signal branch. We designed two arrangements of combiners' mode field adapters. Our numerical simulations estimates losses in signal branches of optimized combiners of 0.23 dB for the first design and 0.16 dB for the second design for SMF-28 input fiber and SMF-28 matched output double clad fiber for the wavelength of 2000 nm. The splice losses of the actual combiner are expected to be even lower thanks to dopant diffusion during the splicing process.

Single-walled carbon nanotube electromechanical switching behavior with shoulder slip

NASA Astrophysics Data System (ADS)

Ryan, Peter; Wu, Yu-Chiao; Somu, Sivasubramanian; Adams, George; McGruer, Nicol

2011-04-01

Several electromechanical devices, each consisting of a small bundle of single-walled carbon nanotubes suspended over an actuation electrode, have been fabricated and operated electrically. The nanotubes are assembled on the electrodes using dielectrophoresis, a potential high-rate nanomanufacturing process. A large decrease in the threshold voltage was seen after the first actuation. This is a result of the nanotubes sliding inward on their supports as they are pulled down toward the actuation electrode, leaving slack in the nanotube bundle for subsequent actuations. The electrical measurements agree well with an electromechanical model that uses a literature-reported value of the shear stress between the nanotubes and the SiO2 shoulders. Electrical measurements were performed in dry nitrogen as a large build-up of contamination was seen when the measurements were performed in lab air. We present measurements as well as a detailed mechanics model that support the interpretation of the data.

Post-operative 3D CT feedback improves accuracy and precision in the learning curve of anatomic ACL femoral tunnel placement.

PubMed

Sirleo, Luigi; Innocenti, Massimo; Innocenti, Matteo; Civinini, Roberto; Carulli, Christian; Matassi, Fabrizio

2018-02-01

To evaluate the feedback from post-operative three-dimensional computed tomography (3D-CT) on femoral tunnel placement in the learning process, to obtain an anatomic anterior cruciate ligament (ACL) reconstruction. A series of 60 consecutive patients undergoing primary ACL reconstruction using autologous hamstrings single-bundle outside-in technique were prospectively included in the study. ACL reconstructions were performed by the same trainee-surgeon during his learning phase of anatomic ACL femoral tunnel placement. A CT scan with dedicated tunnel study was performed in all patients within 48 h after surgery. The data obtained from the CT scan were processed into a three-dimensional surface model, and a true medial view of the lateral femoral condyle was used for the femoral tunnel placement analysis. Two independent examiners analysed the tunnel placements. The centre of femoral tunnel was measured using a quadrant method as described by Bernard and Hertel. The coordinates measured were compared with anatomic coordinates values described in the literature [deep-to-shallow distance (X-axis) 28.5%; high-to-low distance (Y-axis) 35.2%]. Tunnel placement was evaluated in terms of accuracy and precision. After each ACL reconstruction, results were shown to the surgeon to receive an instant feedback in order to achieve accurate correction and improve tunnel placement for the next surgery. Complications and arthroscopic time were also recorded. Results were divided into three consecutive series (1, 2, 3) of 20 patients each. A trend to placing femoral tunnel slightly shallow in deep-to-shallow distance and slightly high in high-to-low distance was observed in the first and the second series. A progressive improvement in tunnel position was recorded from the first to second series and from the second to the third series. Both accuracy (+52.4%) and precision (+55.7%) increased from the first to the third series (p < 0.001). Arthroscopic time decreased from a mean of 105 min in the first series to 57 min in the third series (p < 0.001). After 50 ACL reconstructions, a satisfactory anatomic femoral tunnel was reached. Feedback from post-operative 3D-CT is effective in the learning process to improve accuracy and precision of femoral tunnel placement in order to obtain anatomic ACL reconstruction and helps to reduce also arthroscopic time and learning curve. For clinical relevance, trainee-surgeons should use feedback from post-operative 3DCT to learn anatomic ACL femoral tunnel placement and apply it appropriately. Consecutive case series, Level IV.

Cracking the omega code: hydraulic architecture of the cycad leaf axis.

PubMed

Tomlinson, P Barry; Ricciardi, Alison; Huggett, Brett A

2018-03-05

The leaf axis of members of the order Cycadales ('cycads') has long been recognized by its configuration of independent vascular bundles that, in transverse section, resemble the Greek letter omega (hence the 'omega pattern'). This provides a useful diagnostic character for the order, especially when applied to paleobotany. The function of this pattern has never been elucidated. Here we provide a three-dimensional analysis and explain the pattern in terms of the hydraulic architecture of the pinnately compound cycad leaf. The genus Cycas was used as a simple model, because each leaflet is supplied by a single vascular bundle. Sequential sectioning was conducted throughout the leaf axis and photographed with a digital camera. Photographs were registered and converted to a cinematic format, which provided an objective method of analysis. The omega pattern in the petiole can be sub-divided into three vascular components, an abaxial 'circle', a central 'column' and two adaxial 'wings', the last being the only direct source of vascular supply to the leaflets. Each leaflet is supplied by a vascular bundle that has divided or migrated directly from the closest wing bundle. There is neither multiplication nor anastomoses of vascular bundles in the other two components. Thus, as one proceeds from base to apex along the leaf axis, the number of vascular bundles in circle and column components is reduced distally by their uniform migration throughout all components. Consequently, the distal leaflets are irrigated by the more abaxial bundles, guaranteeing uniform water supply along the length of the axis. The omega pattern exemplifies one of the many solutions plants have achieved in supplying distal appendages of an axis with a uniform water supply. Our method presents a model that can be applied to other genera of cycads with more complex vascular organization. © The Author(s) 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Local Surface Reconstruction from MER images using Stereo Workstation

NASA Astrophysics Data System (ADS)

Shin, Dongjoe; Muller, Jan-Peter

2010-05-01

The authors present a semi-automatic workflow that reconstructs the 3D shape of the martian surface from local stereo images delivered by PnCam or NavCam on systems such as the NASA Mars Exploration Rover (MER) Mission and in the future the ESA-NASA ExoMars rover PanCam. The process is initiated with manually selected tiepoints on a stereo workstation which is then followed by a tiepoint refinement, stereo-matching using region growing and Levenberg-Marquardt Algorithm (LMA)-based bundle adjustment processing. The stereo workstation, which is being developed by UCL in collaboration with colleagues at the Jet Propulsion Laboratory (JPL) within the EU FP7 ProVisG project, includes a set of practical GUI-based tools that enable an operator to define a visually correct tiepoint via a stereo display. To achieve platform and graphic hardware independence, the stereo application has been implemented using JPL's JADIS graphic library which is written in JAVA and the remaining processing blocks used in the reconstruction workflow have also been developed as a JAVA package to increase the code re-usability, portability and compatibility. Although initial tiepoints from the stereo workstation are reasonably acceptable as true correspondences, it is often required to employ an optional validity check and/or quality enhancing process. To meet this requirement, the workflow has been designed to include a tiepoint refinement process based on the Adaptive Least Square Correlation (ALSC) matching algorithm so that the initial tiepoints can be further enhanced to sub-pixel precision or rejected if they fail to pass the ALSC matching threshold. Apart from the accuracy of reconstruction, it is obvious that the other criterion to assess the quality of reconstruction is the density (or completeness) of reconstruction, which is not attained in the refinement process. Thus, we re-implemented a stereo region growing process, which is a core matching algorithm within the UCL-HRSC reconstruction workflow. This algorithm's performance is reasonable even for close-range imagery so long as the stereo -pair does not too large a baseline displacement. For post-processing, a Bundle Adjustment (BA) is used to optimise the initial calibration parameters, which bootstrap the reconstruction results. Amongst many options for the non-linear optimisation, the LMA has been adopted due to its stability so that the BA searches the best calibration parameters whilst iteratively minimising the re-projection errors of the initial reconstruction points. For the evaluation of the proposed method, the result of the method is compared with the reconstruction from a disparity map provided by JPL using their operational processing system. Visual and quantitative comparison will be presented as well as updated camera parameters. As part of future work, we will investigate a method expediting the processing speed of the stereo region growing process and look into the possibility of extending the use of the stereo workstation to orbital image processing. Such an interactive stereo workstation can also be used to digitize points and line features as well as assess the accuracy of stereo processed results produced from other stereo matching algorithms available from within the consortium and elsewhere. It can also provide "ground truth" when suitably refined for stereo matching algorithms as well as provide visual cues as to why these matching algorithms sometimes fail to mitigate this in the future. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 218814 "PRoVisG".

3D reconstruction from multi-view VHR-satellite images in MicMac

NASA Astrophysics Data System (ADS)

Rupnik, Ewelina; Pierrot-Deseilligny, Marc; Delorme, Arthur

2018-05-01

This work addresses the generation of high quality digital surface models by fusing multiple depths maps calculated with the dense image matching method. The algorithm is adapted to very high resolution multi-view satellite images, and the main contributions of this work are in the multi-view fusion. The algorithm is insensitive to outliers, takes into account the matching quality indicators, handles non-correlated zones (e.g. occlusions), and is solved with a multi-directional dynamic programming approach. No geometric constraints (e.g. surface planarity) or auxiliary data in form of ground control points are required for its operation. Prior to the fusion procedures, the RPC geolocation parameters of all images are improved in a bundle block adjustment routine. The performance of the algorithm is evaluated on two VHR (Very High Resolution)-satellite image datasets (Pléiades, WorldView-3) revealing its good performance in reconstructing non-textured areas, repetitive patterns, and surface discontinuities.

Fiber tracking of brain white matter based on graph theory.

PubMed

Lu, Meng

2015-01-01

Brain white matter tractography is reconstructed via diffusion-weighted magnetic resonance images. Due to the complex structure of brain white matter fiber bundles, fiber crossing and fiber branching are abundant in human brain. And regular methods with diffusion tensor imaging (DTI) can't accurately handle this problem. the biggest problems of the brain tractography. Therefore, this paper presented a novel brain white matter tractography method based on graph theory, so the fiber tracking between two voxels is transformed into locating the shortest path in a graph. Besides, the presented method uses Q-ball imaging (QBI) as the source data instead of DTI, because QBI can provide accurate information about multiple fiber crossing and branching in one voxel using orientation distribution function (ODF). Experiments showed that the presented method can accurately handle the problem of brain white matter fiber crossing and branching, and reconstruct brain tractograhpy both in phantom data and real brain data.

X-ray luminescence computed tomography imaging via multiple intensity weighted narrow beam irradiation

NASA Astrophysics Data System (ADS)

Feng, Bo; Gao, Feng; Zhao, Huijuan; Zhang, Limin; Li, Jiao; Zhou, Zhongxing

2018-02-01

The purpose of this work is to introduce and study a novel x-ray beam irradiation pattern for X-ray Luminescence Computed Tomography (XLCT), termed multiple intensity-weighted narrow-beam irradiation. The proposed XLCT imaging method is studied through simulations of x-ray and diffuse lights propagation. The emitted optical photons from X-ray excitable nanophosphors were collected by optical fiber bundles from the right-side surface of the phantom. The implementation of image reconstruction is based on the simulated measurements from 6 or 12 angular projections in terms of 3 or 5 x-ray beams scanning mode. The proposed XLCT imaging method is compared against the constant intensity weighted narrow-beam XLCT. From the reconstructed XLCT images, we found that the Dice similarity and quantitative ratio of targets have a certain degree of improvement. The results demonstrated that the proposed method can offer simultaneously high image quality and fast image acquisition.

Compressive force generation by a bundle of living biofilaments

NASA Astrophysics Data System (ADS)

Ramachandran, Sanoop; Ryckaert, Jean-Paul

2013-08-01

To study the compressional forces exerted by a bundle of living stiff filaments pressing on a surface, akin to the case of an actin bundle in filopodia structures, we have performed particulate molecular dynamics simulations of a grafted bundle of parallel living (self-assembling) filaments, in chemical equilibrium with a solution of their constitutive monomers. Equilibrium is established as these filaments, grafted at one end to a wall of the simulation box, grow at their chemically active free end, and encounter the opposite confining wall of the simulation box. Further growth of filaments requires bending and thus energy, which automatically limit the populations of longer filaments. The resulting filament sizes distribution and the force exerted by the bundle on the obstacle are analyzed for different grafting densities and different sub- or supercritical conditions, these properties being compared with the predictions of the corresponding ideal confined bundle model. In this analysis, non-ideal effects due to interactions between filaments and confinement effects are singled out. For all state points considered at the same temperature and at the same gap width between the two surfaces, the force per filament exerted on the opposite wall appears to be a function of a rescaled free monomer density hat{ρ }_1^eff. This quantity can be estimated directly from the characteristic length of the exponential filament size distribution P observed in the size domain where these grafted filaments are not in direct contact with the wall. We also analyze the dynamics of the filament contour length fluctuations in terms of effective polymerization (U) and depolymerization (W) rates, where again it is possible to disentangle non-ideal and confinement effects.

Regional variation of white matter development in the cat brain revealed by ex vivo diffusion MR tractography.

PubMed

Dai, Guangping; Das, Avilash; Hayashi, Emiko; Chen, Qin; Takahashi, Emi

2016-11-01

Three-dimensional reconstruction of developing fiber pathways is essential to assessing the developmental course of fiber pathways in the whole brain. We applied diffusion spectrum imaging (DSI) tractography to five juvenile ex vivo cat brains at postnatal day (P) 35, when the degree of myelination varies across brain regions. We quantified diffusion properties (fractional anisotropy [FA] and apparent diffusion coefficient [ADC]) and other measurements (number, volume, and voxel count) on reconstructed pathways for projection (cortico-spinal and thalamo-cortical), corpus callosal, limbic (cingulum and fornix), and association (cortico-cortical) pathways, and characterized regional differences in maturation patterns by assessing diffusion properties. FA values were significantly higher in cortico-cortical pathways within the right hemisphere compared to those within the left hemisphere, while the other measurements for the cortico-cortical pathways within the hemisphere did not show asymmetry. ADC values were not asymmetric in both types of pathways. Interestingly, tract count and volume were significantly larger in the left thalamo-cortical pathways compared to the right thalamo-cortical pathways. The bilateral thalamo-cortical pathways showed high FA values compared to the other fiber pathways. On the other hand, ADC values did not show any differences across pathways studied. These results demonstrate that DSI tractography successfully depicted regional variations of white matter tracts during development when myelination is incomplete. Low FA and high ADC values in the cingulum bundle suggest that the cingulum bundle is less mature than the others at this developmental stage. Copyright © 2016 ISDN. Published by Elsevier Ltd. All rights reserved.

Morphology of the utricular otolith organ in the toadfish, Opsanus tau.

PubMed

Boyle, Richard; Ehsanian, Reza; Mofrad, Alireza; Popova, Yekaterina; Varelas, Joseph

2018-06-15

The utricle provides the vestibular reflex pathways with the sensory codes of inertial acceleration of self-motion and head orientation with respect to gravity to control balance and equilibrium. Here we present an anatomical description of this structure in the adult oyster toadfish and establish a morphological basis for interpretation of subsequent functional studies. Light, scanning, and transmission electron microscopy techniques were applied to visualize the sensory epithelium at varying levels of detail, its neural innervation and its synaptic organization. Scanning electron microscopy was used to visualize otolith mass and morphological polarization patterns of hair cells. Afferent nerve fibers were visualized following labeling with biocytin, and light microscope images were used to make three-dimensional (3-D) reconstructions of individual labeled afferents to identify dendritic morphology with respect to epithelial location. Transmission electron micrographs were compiled to create a serial 3-D reconstruction of a labeled afferent over a segment of its dendritic field and to examine the cell-afferent synaptic contacts. Major observations are: a well-defined striola, medial and lateral extra-striolar regions with a zonal organization of hair bundles; prominent lacinia projecting laterally; dependence of hair cell density on macular location; narrow afferent dendritic fields that follow the hair bundle polarization; synaptic specializations issued by afferents are typically directed towards a limited number of 7-13 hair cells, but larger dendritic fields in the medial extra-striola can be associated with > 20 hair cells also; and hair cell synaptic bodies can be confined to only an individual afferent or can synapse upon several afferents. © 2018 Wiley Periodicals, Inc.

Evaluation of computational endomicroscopy architectures for minimally-invasive optical biopsy

NASA Astrophysics Data System (ADS)

Dumas, John P.; Lodhi, Muhammad A.; Bajwa, Waheed U.; Pierce, Mark C.

2017-02-01

We are investigating compressive sensing architectures for applications in endomicroscopy, where the narrow diameter probes required for tissue access can limit the achievable spatial resolution. We hypothesize that the compressive sensing framework can be used to overcome the fundamental pixel number limitation in fiber-bundle based endomicroscopy by reconstructing images with more resolvable points than fibers in the bundle. An experimental test platform was assembled to evaluate and compare two candidate architectures, based on introducing a coded amplitude mask at either a conjugate image or Fourier plane within the optical system. The benchtop platform consists of a common illumination and object path followed by separate imaging arms for each compressive architecture. The imaging arms contain a digital micromirror device (DMD) as a reprogrammable mask, with a CCD camera for image acquisition. One arm has the DMD positioned at a conjugate image plane ("IP arm"), while the other arm has the DMD positioned at a Fourier plane ("FP arm"). Lenses were selected and positioned within each arm to achieve an element-to-pixel ratio of 16 (230,400 mask elements mapped onto 14,400 camera pixels). We discuss our mathematical model for each system arm and outline the importance of accounting for system non-idealities. Reconstruction of a 1951 USAF resolution target using optimization-based compressive sensing algorithms produced images with higher spatial resolution than bicubic interpolation for both system arms when system non-idealities are included in the model. Furthermore, images generated with image plane coding appear to exhibit higher spatial resolution, but more noise, than images acquired through Fourier plane coding.

Focal ratio degradation in lightly fused hexabundles

NASA Astrophysics Data System (ADS)

Bryant, J. J.; Bland-Hawthorn, J.; Fogarty, L. M. R.; Lawrence, J. S.; Croom, S. M.

2014-02-01

We are now moving into an era where multi-object wide-field surveys, which traditionally use single fibres to observe many targets simultaneously, can exploit compact integral field units (IFUs) in place of single fibres. Current multi-object integral field instruments such as Sydney-AAO Multi-object Integral field spectrograph have driven the development of new imaging fibre bundles (hexabundles) for multi-object spectrographs. We have characterized the performance of hexabundles with different cladding thicknesses and compared them to that of the same type of bare fibre, across the range of fill fractions and input f-ratios likely in an IFU instrument. Hexabundles with 7-cores and 61-cores were tested for focal ratio degradation (FRD), throughput and cross-talk when fed with inputs from F/3.4 to >F/8. The five 7-core bundles have cladding thickness ranging from 1 to 8 μm, and the 61-core bundles have 5 μm cladding. As expected, the FRD improves as the input focal ratio decreases. We find that the FRD and throughput of the cores in the hexabundles match the performance of single fibres of the same material at low input f-ratios. The performance results presented can be used to set a limit on the f-ratio of a system based on the maximum loss allowable for a planned instrument. Our results confirm that hexabundles are a successful alternative for fibre imaging devices for multi-object spectroscopy on wide-field telescopes and have prompted further development of hexabundle designs with hexagonal packing and square cores.

Medial Patellofemoral Ligament Reconstruction Procedure Using a Suspensory Femoral Fixation System

PubMed Central

Nakagawa, Shuji; Arai, Yuji; Kan, Hiroyuki; Ueshima, Keiichiro; Ikoma, Kazuya; Terauchi, Ryu; Kubo, Toshikazu

2013-01-01

Recurrent patellar dislocation has recently been treated with anatomic medial patellofemoral ligament (MPFL) reconstruction using a semitendinosus muscle tendon. Although it is necessary to add tension to fix the tendon graft without loading excess stress on the patellofemoral joint, adjustment of the tension can be difficult. To resolve this problem, we developed an MPFL reconstruction procedure using the ToggleLoc Fixation Device (Biomet, Warsaw, IN), in which the semitendinosus muscle tendon is folded and used as a double-bundle tendon graft and 2 bone tunnels and 1 bone tunnel are made on the patellar and femoral sides, respectively. The patellar side of the tendon graft is fixed with an EndoButton (Smith & Nephew, London, England), and the femoral side is fixed with the ToggleLoc. Stepless adjustment of tension of the tendon graft is possible by reducing the size of the loop of the ToggleLoc hung onto the tendon graft. It may be useful to position the patella in the center of the femoral sulcus by confirming the patellofemoral joint fitting. Stability can be confirmed by loading lateral stress on the patella in the extended knee joint. This procedure is less invasive because opening of the lateral side of the femur is not necessary, and it may be useful for MPFL reconstruction. PMID:24892014

Isopeptide bonds of the major pilin protein BcpA influence pilus structure and bundle formation on the surface of Bacillus cereus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendrickx, Antoni P.A.; Poor, Catherine B.; Jureller, Justin E.

Bacillus cereus strains elaborate pili on their surface using a mechanism of sortase-mediated cross-linking of major and minor pilus components. Here we used a combination of electron microscopy and atomic force microscopy to visualize these structures. Pili occur as single, double or higher order assemblies of filaments formed from monomers of the major pilin, BcpA, capped by the minor pilin, BcpB. Previous studies demonstrated that within assembled pili, four domains of BcpA -- CNA{sub 1}, CNA{sub 2}, XNA and CNA{sub 3} -- each acquire intramolecular lysine-asparagine isopeptide bonds formed via catalytic glutamic acid or aspartic acid residues. Here we showedmore » that mutants unable to form the intramolecular isopeptide bonds in the CNA2 or CNA3 domains retain the ability to form pilus bundles. A mutant lacking the CNA{sub 1} isopeptide bond assembled deformed pilin subunits that failed to associate as bundles. X-ray crystallography revealed that the BcpA variant Asp{sup 312}Ala, lacking an aspartyl catalyst, did not generate the isopeptide bond within the jelly-roll structure of XNA. The Asp{sup 312}Ala mutant was also unable to form bundles and promoted the assembly of deformed pili. Thus, structural integrity of the CNA{sub 1} and XNA domains are determinants for the association of pili into higher order bundle structures and determine native pilus structure.« less

Cortico-Cortical, Cortico-Striatal, and Cortico-Thalamic White Matter Fiber Tracts Generated in the Macaque Brain via Dynamic Programming

PubMed Central

Lal, Rakesh M.; An, Michael; Poynton, Clare B.; Li, Muwei; Jiang, Hangyi; Oishi, Kenichi; Selemon, Lynn D.; Mori, Susumu; Miller, Michael I.

2013-01-01

Abstract Probabilistic methods have the potential to generate multiple and complex white matter fiber tracts in diffusion tensor imaging (DTI). Here, a method based on dynamic programming (DP) is introduced to reconstruct fibers pathways whose complex anatomical structures cannot be resolved beyond the resolution of standard DTI data. DP is based on optimizing a sequentially additive cost function derived from a Gaussian diffusion model whose covariance is defined by the diffusion tensor. DP is used to determine the optimal path between initial and terminal nodes by efficiently searching over all paths, connecting the nodes, and choosing the path in which the total probability is maximized. An ex vivo high-resolution scan of a macaque hemi-brain is used to demonstrate the advantages and limitations of DP. DP can generate fiber bundles between distant cortical areas (superior longitudinal fasciculi, arcuate fasciculus, uncinate fasciculus, and fronto-occipital fasciculus), neighboring cortical areas (dorsal and ventral banks of the principal sulcus), as well as cortical projections to the hippocampal formation (cingulum bundle), neostriatum (motor cortical projections to the putamen), thalamus (subcortical bundle), and hippocampal formation projections to the mammillary bodies via the fornix. Validation is established either by comparison with in vivo intracellular transport of horseradish peroxidase in another macaque monkey or by comparison with atlases. DP is able to generate known pathways, including crossing and kissing tracts. Thus, DP has the potential to enhance neuroimaging studies of cortical connectivity. PMID:23879573

Architecture of the Suprahyoid Muscles: A Volumetric Musculoaponeurotic Analysis.

PubMed

Shaw, Stephanie M; Martino, Rosemary; Mahdi, Ali; Sawyer, Forrest Kip; Mathur, Sunita; Hope, Andrew; Agur, Anne M

2017-10-17

Suprahyoid muscles play a critical role in swallowing. The arrangement of the fiber bundles and aponeuroses has not been investigated volumetrically, even though muscle architecture is an important determinant of function. Thus, the purpose was to digitize, model in three dimensions, and quantify the architectural parameters of the suprahyoid muscles to determine and compare their relative functional capabilities. Fiber bundles and aponeuroses from 11 formalin-embalmed specimens were serially dissected and digitized in situ. Data were reconstructed in three dimensions using Autodesk Maya. Architectural parameters were quantified, and data were compared using independent samples t-tests and analyses of variance. Based on architecture and attachment sites, suprahyoid muscles were divided into 3 groups: anteromedial, superolateral, and superoposterior. Architectural parameters differed significantly (p < .05) across muscles and across the 3 groups, suggesting differential roles in hyoid movement during swallowing. When activated simultaneously, anteromedial and superoposterior muscle groups could work together to elevate the hyoid. The results suggest that the suprahyoid muscles can have individualized roles in hyoid excursion during swallowing. Muscle balance may be important for identifying and treating hyolaryngeal dysfunction in patients with dysphagia.

Robust fiber clustering of cerebral fiber bundles in white matter

NASA Astrophysics Data System (ADS)

Yao, Xufeng; Wang, Yongxiong; Zhuang, Songlin

2014-11-01

Diffusion tensor imaging fiber tracking (DTI-FT) has been widely accepted in the diagnosis and treatment of brain diseases. During the rendering pipeline of specific fiber tracts, the image noise and low resolution of DTI would lead to false propagations. In this paper, we propose a robust fiber clustering (FC) approach to diminish false fibers from one fiber tract. Our algorithm consists of three steps. Firstly, the optimized fiber assignment continuous tracking (FACT) is implemented to reconstruct one fiber tract; and then each curved fiber in the fiber tract is mapped to a point by kernel principal component analysis (KPCA); finally, the point clouds of fiber tract are clustered by hierarchical clustering which could distinguish false fibers from true fibers in one tract. In our experiment, the corticospinal tract (CST) in one case of human data in vivo was used to validate our method. Our method showed reliable capability in decreasing the false fibers in one tract. In conclusion, our method could effectively optimize the visualization of fiber bundles and would help a lot in the field of fiber evaluation.

Optical aberrations in underwater photogrammetry with flat and hemispherical dome ports

NASA Astrophysics Data System (ADS)

Menna, Fabio; Nocerino, Erica; Remondino, Fabio

2017-06-01

The paper analyses differences between dome and flat port housings used for underwater photogrammetry. The underwater environment negatively affects image quality and 3D reconstructions, but this influence on photogrammetric measurements, so far, has not been addressed properly in the literature. In this work, motivations behind the need for systematic underwater calibrations are provided, then experimental tests using a specifically designed photogrammetric modular test object in laboratory and at sea are reported. The experiments are carried out using a Nikon D750 24 Mpx DSLR camera with a 24 mm f2.8 AF/D lens coupled with a NIMAR NI3D750ZM housing, equipped first with a dome and, successively, with a flat port. To quantify the degradation of image quality, MTF measurements are carried out, then the outcomes of self-calibrating bundle adjustment calibrations are shown and commented. Optical phenomena like field curvature as well as chromatic aberration and astigmatism are analysed and their implications on the degradation of image quality is factored in the bundle adjustment through a different weighting of 2D image observations.

Effects of Mechanical Loading on the Dynamics of Hair-Cell Stereociliary Bundles

NASA Astrophysics Data System (ADS)

Fredrickson, Lea

Hearing is remarkably sensitive and still not entirely understood. Hair cells of the inner ear are the mechano-electrical transducers of sound and understanding how they function is essential to the understanding of hearing in general. Spontaneous oscillations exhibited by stereociliary bundles of the bullfrog sacculus provide a useful probe for the study of the hair cells' internal dynamic state. In this work we study the effects of mechanical loading on these hair-cell bundles in order to study their dynamics. When applying stiffness loads, we find that the spontaneous oscillation profile changes from multimode to single mode with light loading, and decreases in amplitude and increases in frequency with stiffer loads. We also find that tuning decreases with increasing load such that at loads comparable to in vivo conditions the tuning is flat. We further explore loading via deflections to hair cell bundles, both in the form of steady-state offsets and slow ramps. We find that steady state offsets lead to significant modulation of the characteristic frequency of response, decreasing the frequency in the channels closed direction (negative) and increasing it in the channels open direction (positive). Attachment to the overlying membrane was found, in vitro, to affect bundle offset position in hair cells of the bullfrog sacculus. Application of similar offsets on free-standing, spontaneously oscillating hair bundles shows modulation of their dynamic state, i.e. oscillation profile, characteristic frequency, and response to stimulus. Large offsets are found to arrest spontaneous oscillations, which recover upon reversal of the stimulus. The dynamical state of the hair bundle is dependent on both the history and direction of the offset stimulus. Oscillation suppression occurs much more readily in the negative direction and the bundle behavior approaching quiescence is distinct from that in the positive direction. With the change in spontaneous oscillation frequency and profile comes a change in the phase-locked response amplitude, dependent on bundle offset, winch extends the range of detection frequencies of the hair cell. We explore the broadband phase-locked response of spontaneously oscillating saccular hair cell bundles subject to time-dependent mechanical deflections. The experimental phase-locked amplitude shows an Arnold Tongue, consistent with theoretically predicted dynamical behavior. An offset that steadily increases in time, imposed on the position of the bundle to explore its dynamics at the zero frequency limit, is observed to progressively suppress spontaneous oscillations in a transition that displays strong frequency modulation, with the frequency vanishing at the critical point. When deflected at a faster rate and when allowed to recover to the oscillatory regime, the bundles also displayed a modulation in the amplitude of oscillation. We propose the dynamics of this transition to be dominated by a multi-critical region such that slight variations of a control parameter can produce either an infinite-period, supercritical Hopf, or Bogdanov-Takens bifurcation.

On the properties of a bundle of flexible actin filaments in an optical trap.

PubMed

Perilli, Alessia; Pierleoni, Carlo; Ciccotti, Giovanni; Ryckaert, Jean-Paul

2016-06-28

We establish the statistical mechanics framework for a bundle of Nf living and uncrosslinked actin filaments in a supercritical solution of free monomers pressing against a mobile wall. The filaments are anchored normally to a fixed planar surface at one of their ends and, because of their limited flexibility, they grow almost parallel to each other. Their growing ends hit a moving obstacle, depicted as a second planar wall, parallel to the previous one and subjected to a harmonic compressive force. The force constant is denoted as the trap strength while the distance between the two walls as the trap length to make contact with the experimental optical trap apparatus. For an ideal solution of reactive filaments and free monomers at fixed free monomer chemical potential μ1, we obtain the general expression for the grand potential from which we derive averages and distributions of relevant physical quantities, namely, the obstacle position, the bundle polymerization force, and the number of filaments in direct contact with the wall. The grafted living filaments are modeled as discrete Wormlike chains, with F-actin persistence length ℓp, subject to discrete contour length variations ±d (the monomer size) to model single monomer (de)polymerization steps. Rigid filaments (ℓp = ∞), either isolated or in bundles, all provide average values of the stalling force in agreement with Hill's predictions Fs (H)=NfkBTln(ρ1/ρ1c)/d, independent of the average trap length. Here ρ1 is the density of free monomers in the solution and ρ1c its critical value at which the filament does not grow nor shrink in the absence of external forces. Flexible filaments (ℓp < ∞) instead, for values of the trap strength suitable to prevent their lateral escape, provide an average bundle force and an average trap length slightly larger than the corresponding rigid cases (few percents). Still the stalling force remains nearly independent on the average trap length, but results from the product of two strongly L-dependent contributions: the fraction of touching filaments ∝〈L〉(O.T.) (2) and the single filament buckling force ∝〈L〉(O.T.) (-2).

Commissural axons of the mouse cochlear nucleus.

PubMed

Brown, M Christian; Drottar, Marie; Benson, Thane E; Darrow, Keith

2013-05-01

The axons of commissural neurons that project from one cochlear nucleus to the other were studied after labeling with anterograde tracer. Injections were made into the dorsal subdivision of the cochlear nucleus in order to restrict labeling only to the group of commissural neurons that gave off collaterals to, or were located in, this subdivision. The number of labeled commissural axons in each injection was correlated with the number of labeled radiate multipolar neurons, suggesting radiate neurons as the predominant origin of the axons. The radiate commissural axons are thick and myelinated, and they exit the dorsal acoustic stria of the injected cochlear nucleus to cross the brainstem in the dorsal half, near the crossing position of the olivocochlear bundle. They enter the opposite cochlear nucleus via the dorsal and ventral acoustic stria and at its medial border. Reconstructions of single axons demonstrate that terminations are mostly in the core and typically within a single subdivision of the cochlear nucleus. Extents of termination range from narrow to broad along both the dorsoventral (i.e., tonotopic) and the rostrocaudal dimensions. In the electron microscope, labeled swellings form synapses that are symmetric (in that there is little postsynaptic density), a characteristic of inhibitory synapses. Our labeled axons do not appear to include excitatory commissural axons that end in edge regions of the nucleus. Radiate commissural axons could mediate the broadband inhibition observed in responses to contralateral sound, and they may balance input from the two ears with a quick time course. Copyright © 2012 Wiley Periodicals, Inc.

Commissural Axons of the Mouse Cochlear Nucleus

PubMed Central

Brown, M. Christian; Drottar, Marie; Benson, Thane E.; Darrow, Keith

2012-01-01

The axons of commissural neurons that project from one cochlear nucleus to the other were studied after labeling with anterograde tracer. Injections were made into the dorsal subdivision of the cochlear nucleus in order to restrict labeling only to the group of commissural neurons that gave off collaterals to, or were located in, this subdivision. The number of labeled commissural axons in each injection was correlated with the number of labeled radiate multipolar neurons, suggesting radiate neurons as the predominant origin of the axons. The radiate commissural axons are thick and myelinated, and they exit the dorsal acoustic stria of the injected cochlear nucleus to cross the brainstem in the dorsal half, near the crossing position of the olivocochlear bundle. They enter the opposite cochlear nucleus via the dorsal and ventral acoustic stria and at its medial border. Reconstructions of single axons demonstrate that terminations are mostly in the core and typically within a single subdivision of the cochlear nucleus. Extents of termination range from narrow to broad along both the dorso-ventral (i.e. tonotopic) and rostro-caudal dimensions. In the electron microscope, labeled swellings form synapses that are symmetric (in that there is little postsynaptic density), a characteristic of inhibitory synapses. Our labeled axons do not appear to include excitatory commissural axons that end in edge regions of the nucleus. Radiate commissural axons could mediate the broad-band inhibition observed in responses to contralateral sound, and they may balance input from the two ears on a quick time course. PMID:23124982

The influence of chemical composition of LNG on the supercritical heat transfer in an intermediate fluid vaporizer

NASA Astrophysics Data System (ADS)

Xu, Shuangqing; Chen, Xuedong; Fan, Zhichao; Chen, Yongdong; Nie, Defu; Wu, Qiaoguo

2018-04-01

A three-dimensional transient computational fluid dynamics (CFD) model has been established for the simulations of supercritical heat transfer of real liquefied natural gas (LNG) mixture in a single tube and a tube bundle of an intermediate fluid vaporizer (IFV). The influence of chemical composition of LNG on the thermal performance has been analyzed. The results have also been compared with those obtained from the one-dimensional steady-state calculations using the distributed parameter model (DPM). It is found that the current DPM approach can give reasonable prediction accuracy for the thermal performance in the tube bundle but unsatisfactory prediction accuracy for that in a single tube as compared with the corresponding CFD data. As benchmarked against pure methane, the vaporization of an LNG containing about 90% (mole fraction) of methane would lead to an absolute deviation of 5.5 K in the outlet NG temperature and a maximum relative deviation of 11.4% in the tube side HTC in a bundle of about 816 U tubes at the inlet pressure of 12 MPa and mass flux of 200 kg·m-2·s-1. It is concluded that the influence of LNG composition on the thermal performance should be taken into consideration in order to obtain an economic and reliable design of an IFV.

3D skin surface reconstruction from a single image by merging global curvature and local texture using the guided filtering for 3D haptic palpation.

PubMed

Lee, K; Kim, M; Kim, K

2018-05-11

Skin surface evaluation has been studied using various imaging techniques. However, all these studies had limited impact because they were performed using visual exam only. To improve on this scenario with haptic feedback, we propose 3D reconstruction of the skin surface using a single image. Unlike extant 3D skin surface reconstruction algorithms, we utilize the local texture and global curvature regions, combining the results for reconstruction. The first entails the reconstruction of global curvature, achieved by bilateral filtering that removes noise on the surface while maintaining the edge (ie, furrow) to obtain the overall curvature. The second entails the reconstruction of local texture, representing the fine wrinkles of the skin, using an advanced form of bilateral filtering. The final image is then composed by merging the two reconstructed images. We tested the curvature reconstruction part by comparing the resulting curvatures with measured values from real phantom objects while local texture reconstruction was verified by measuring skin surface roughness. Then, we showed the reconstructed result of our proposed algorithm via the reconstruction of various real skin surfaces. The experimental results demonstrate that our approach is a promising technology to reconstruct an accurate skin surface with a single skin image. We proposed 3D skin surface reconstruction using only a single camera. We highlighted the utility of global curvature, which has not been considered important in the past. Thus, we proposed a new method for 3D reconstruction that can be used for 3D haptic palpation, dividing the concepts of local and global regions. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Uncommon formation of two antiparallel sperm bundles per cyst in tenebrionid beetles (Coleoptera)

NASA Astrophysics Data System (ADS)

Dias, Glenda; Yotoko, Karla S. C.; Gomes, Luiz F.; Lino-Neto, José

2012-09-01

Several species of Tenebrionidae are stored-grain pests. Since they belong to a specious family, the systematics of these beetles is still in doubt. In insects, spermatogenesis and the spermatozoa exhibit great diversity, and are therefore commonly used in phylogenetic and taxonomic analyses. During the spermatogenetic process in these organisms, the cells originating from a single spermatogonium develop synchronically in groups referred to as cysts. At the end of this process, there is usually only one sperm bundle per cyst, with all the cells in the same orientation. This paper details the spermiogenesis of the tenebrionid beetles Tenebrio molitor, Zophobas confusa, Tribolium castaneum and Palembus dermestoides using whole mount and histological sections of the cysts. In these species, spermatogenesis is similar to that which occurs in most insects. However, during spermiogenesis, the nuclei of the spermatids migrate to two opposite regions at the periphery of the cyst, leading to the uncommon formation of two bundles of spermatozoa per cyst. This feature is possibly an apomorphy for Tenebrionidae.

The pH sensibility of actin-bundling LIM proteins is governed by the acidic properties of their C-terminal domain.

PubMed

Moes, Danièle; Hoffmann, Céline; Dieterle, Monika; Moreau, Flora; Neumann, Katrin; Papuga, Jessica; Furtado, Angela Tavares; Steinmetz, André; Thomas, Clément

2015-08-19

Actin-bundling Arabidopsis LIM proteins are subdivided into two subfamilies differing in their pH sensitivity. Widely-expressed WLIMs are active under low and high physiologically-relevant pH conditions, whereas pollen-enriched PLIMs are inactivated by pH values above 6.8. By a domain swapping approach we identified the C-terminal (Ct) domain of PLIMs as the domain responsible for pH responsiveness. Remarkably, this domain conferred pH sensitivity to LIM proteins, when provided "in trans" (i.e., as a single, independent, peptide), indicating that it operates through the interaction with another domain. An acidic 6xc-Myc peptide functionally mimicked the Ct domain of PLIMs and efficiently inhibited LIM actin bundling activity under high pH conditions. Together, our data suggest a model where PLIMs are regulated by an intermolecular interaction between their acidic Ct domain and another, yet unidentified, domain. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

In Situ Strength Model for Continuous Fibers and Multi-Scale Modeling the Fracture of C/SiC Composites

NASA Astrophysics Data System (ADS)

Zhang, Sheng; Gao, Xiguang; Song, Yingdong

2018-04-01

A new in situ strength model of carbon fibers was developed based on the distribution of defects to predict the stress-strain response and the strength of C/SiC composites. Different levels of defects in the fibers were considered in this model. The defects in the fibers were classified by their effects on the strength of the fiber. The strength of each defect and the probability that the defect appears were obtained from the tensile test of single fibers. The strength model of carbon fibers was combined with the shear-lag model to predict the stress-strain responses and the strengths of fiber bundles and C/SiC minicomposites. To verify the strength model, tensile tests were performed on fiber bundles and C/SiC minicomposites. The predicted and experimental results were in good agreement. Effects of the fiber length, the fiber number and the heat treatment on the final strengths of fiber bundles and C/SiC minicomposites were also discussed.

Dispersion of Single Wall Carbon Nanotubes by in situ Polymerization Under Sonication

NASA Technical Reports Server (NTRS)

Park, Cheol; Ounaies, Zoubeida; Watson, Kent A.; Crooks, Roy E.; Smith, Joseph, Jr.; Lowther, Sharon E.; Connell, John W.; Siochi, Emilie J.; Harrison, Joycelyn S.; St.Clair, Terry L.

2002-01-01

Single wall nanotube reinforced polyimide nanocomposites were synthesized by in situ polymerization of monomers of interest in the presence of sonication. This process enabled uniform dispersion of single wall carbon nanotube (SWNT) bundles in the polymer matrix. The resultant SWNT-polyimide nanocomposite films were electrically conductive (antistatic) and optically transparent with significant conductivity enhancement (10 orders of magnitude) at a very low loading (0.1 vol%). Mechanical properties as well as thermal stability were also improved with the incorporation of the SWNT.

Hair cell regeneration in the bullfrog vestibular otolith organs following aminoglycoside toxicity

NASA Technical Reports Server (NTRS)

Baird, R. A.; Torres, M. A.; Schuff, N. R.

1993-01-01

Adult bullfrog were given single intraotic injections of the aminoglycoside antibiotic gentamicin sulfate and sacrificed at postinjection times ranging from 0.5 to 9 days. The saccular and utricular maculae of normal and injected animals were examined in wholemount and cross-section. Intraotic 200 microM gentamicin concentrations resulted in the uniform destruction of the hair bundles and, at later times, the cell bodies of saccular hair cells. In the utriculus, striolar hair cells were selectively damaged while extrastriolar hair cells were relatively unaffected. Regenerating hair cells, identified in sectioned material by their small cell bodies and short, well-formed hair bundles, were seen in the saccular and utricular maculae as early as 24-48 h postinjection. Immature versions of mature hair cell types in both otolith organs were recognized by the presence or absence of a bulbed kinocilia and the relative lengths of their kinocilia and longest stereocilia. Utricular hair cell types with kinocilia longer than their longest stereocilia were observed at earlier than hair cell types with shorter kinocilia. In the sacculus, the hair bundles of gentamicin-treated animals, even at 9 days postinjection, were significantly smaller than those of normal animals. The hair bundles of utricular hair cells, on the other hand, reached full maturity within the same time period.

Hair cell regeneration in the bullfrog vestibular otolith organs following aminoglycoside toxicity

NASA Technical Reports Server (NTRS)

Baird, Richard A.; Torres, M. A.; Schuff, N. R.

1994-01-01

Adult bullfrogs were given single intraotic injections of the aminoglycoside antibiotic gentamicin sulfate and sacrificed at postinjection times ranging from 0.5 to 9 days. The saccular and utricular maculae of normal and injected animals were examined in wholemount and cross-section. Intraotic 200 (mu) M gentamicin concentrations resulted in the uniform destruction of the hair bundles and, at later times, the cell bodies of saccular hair cells. In the utriculus, striolar hair cells were selectively damaged while extrastriolar hair cells were relatively unaffected. Regenerating hair cells, identified in sectioned material by their small cell bodies and short, well-formed hair bundles, were seen in the saccular and utricular maculae as early as 24-48 h postinjection. Immature versions of mature hair cell types in both otolith organs were recognized by the presence of absence of a bulbed kinocilia and the relative lengths of their kinocilia and longest sterocilia. Utricular hair cell types with kinocilia longer than their longest stereocilia were observed at earlier times than hair cell types with shorter kinocilia. In the same sacculus, the hair bundles of gentamicin-treated animals, even at 9 days postinjection, were significantly smaller than those of normal animals. The hair bundles of utricular hair cells, on the other hand, reached full maturity within the same time period.

Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials.

PubMed

Jang, Seon-Min; Yang, Su Chul

2018-06-08

Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO 2 epitaxial growth and BaTiO 3 conversion. Through the TiO 2 epitaxial growth on FTO substrate, (001) oriented TiO 2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO 2 NBA was conducted to enlarge the surface area for effective Ba 2+ ion diffusion during the perovskite conversion process from TiO 2 to BaTiO 3 . The final structure of perovskite BaTiO 3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO 3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

Influence of carbon nanotubes on the buckling of microtubule bundles in viscoelastic cytoplasm using nonlocal strain gradient theory

NASA Astrophysics Data System (ADS)

Farajpour, A.; Rastgoo, A.

Carbon nanotubes are a new class of microtubule-stabilizing agents since they interact with protein microtubules in living cells, interfering with cell division and inducing apoptosis. In the present work, a modified beam model is developed to investigate the effect of carbon nanotubes on the buckling of microtubule bundles in living cell. A realistic interaction model is employed using recent experimental data on the carbon nanotube-stabilized microtubules. Small scale and surface effects are taken into account applying the nonlocal strain gradient theory and surface elasticity theory. Pasternak model is used to describe the normal and shearing effects of enclosing filament matrix on the buckling behavior of the system. An exact solution is obtained for the buckling growth rates of the mixed bundle in viscoelastic surrounding cytoplasm. The present results are compared with those reported in the open literature for single microtubules and an excellent agreement is found. Finally, the effects of different parameters such as the size, chirality, position and surface energy of carbon nanotubes on the buckling growth rates of microtubule bundles are studied. It is found that the buckling growth rate may increase or decrease by adding carbon nanotubes, depending on the diameter and chirality of carbon nanotubes.

Incremental Implicit Learning of Bundles of Statistical Patterns

PubMed Central

Qian, Ting; Jaeger, T. Florian; Aslin, Richard N.

2016-01-01

Forming an accurate representation of a task environment often takes place incrementally as the information relevant to learning the representation only unfolds over time. This incremental nature of learning poses an important problem: it is usually unclear whether a sequence of stimuli consists of only a single pattern, or multiple patterns that are spliced together. In the former case, the learner can directly use each observed stimulus to continuously revise its representation of the task environment. In the latter case, however, the learner must first parse the sequence of stimuli into different bundles, so as to not conflate the multiple patterns. We created a video-game statistical learning paradigm and investigated 1) whether learners without prior knowledge of the existence of multiple “stimulus bundles” — subsequences of stimuli that define locally coherent statistical patterns — could detect their presence in the input, and 2) whether learners are capable of constructing a rich representation that encodes the various statistical patterns associated with bundles. By comparing human learning behavior to the predictions of three computational models, we find evidence that learners can handle both tasks successfully. In addition, we discuss the underlying reasons for why the learning of stimulus bundles occurs even when such behavior may seem irrational. PMID:27639552

Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials

NASA Astrophysics Data System (ADS)

Jang, Seon-Min; Yang, Su Chul

2018-06-01

Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO2 epitaxial growth and BaTiO3 conversion. Through the TiO2 epitaxial growth on FTO substrate, (001) oriented TiO2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO2 NBA was conducted to enlarge the surface area for effective Ba2+ ion diffusion during the perovskite conversion process from TiO2 to BaTiO3. The final structure of perovskite BaTiO3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

A three-dimensional study of the musculotendinous and neurovascular architecture of the gracilis muscle: application to functional muscle transfer.

PubMed

Fattah, A Y; Ravichandiran, K; Zuker, R M; Agur, A M R

2013-09-01

Muscle transfer is used to restore function typically using a single vector of contraction. Although its use with two independently functional muscular units has been employed, in order to refine this concept we endeavoured to detail the intramuscular anatomy of gracilis, a muscle commonly used for transfer. A novel method to capture intramuscular fibre bundle and neurovascular arrangement was used to create a three-dimensional (3D) digital model that allowed for accurate representation of the relationships between all the intramuscular structures to facilitate flap planning. Twenty gracilis muscles were harvested from 15 cadavers. All components of the muscle were digitised using a Microscribe G2 Digitiser. The data were exported to the 3D animation software Autodesk(®) Maya(®) 2012 whereupon it was rendered into a 3D model that can be exported as static images or videos. Neurovascular anatomy and muscle architecture were analysed from these models, and fibre bundle length, pennation angle and physiological cross-sectional area were calculated from digitised data. The muscle is composed of a variable number of distinct longitudinal segments with muscle fibres spiralling onto the tendon. The main artery to the muscle has three main intramuscular patterns of distribution. The venae comitantes drain discrete zones without intramuscular macroscopic anastomoses. The minor pedicles form an anastomotic chain along the anterior border of the muscle and all vessels were biased to the deep surface. The nerve is related to the vessels in a variable manner and both run between longitudinal muscular compartments. The digitisation technique may be used to advance knowledge of intramuscular architecture and it demonstrated that the gracilis muscle is comprised of four to seven muscular compartments, each representing a functional unit that may theoretically be differentially activated and could be harnessed for more sophisticated muscle transfers. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Birefringence of single and bundled microtubules.

PubMed

Oldenbourg, R; Salmon, E D; Tran, P T

1998-01-01

We have measured the birefringence of microtubules (MTs) and of MT-based macromolecular assemblies in vitro and in living cells by using the new Pol-Scope. A single microtubule in aqueous suspension and imaged with a numerical aperture of 1.4 had a peak retardance of 0.07 nm. The peak retardance of a small bundle increased linearly with the number of MTs in the bundle. Axonemes (prepared from sea urchin sperm) had a peak retardance 20 times higher than that of single MTs, in accordance with the nine doublets and two singlets arrangement of parallel MTs in the axoneme. Measured filament retardance decreased when the filament was defocused or the numerical aperture of the imaging system was decreased. However, the retardance "area," which we defined as the image retardance integrated along a line perpendicular to the filament axis, proved to be independent of focus and of numerical aperture. These results are in good agreement with a theory that we developed for measuring retardances with imaging optics. Our theoretical concept is based on Wiener's theory of mixed dielectrics, which is well established for nonimaging applications. We extend its use to imaging systems by considering the coherence region defined by the optical set-up. Light scattered from within that region interferes coherently in the image point. The presence of a filament in the coherence region leads to a polarization dependent scattering cross section and to a finite retardance measured in the image point. Similar to resolution measurements, the linear dimension of the coherence region for retardance measurements is on the order lambda/(2 NA), where lambda is the wavelength of light and NA is the numerical aperture of the illumination and imaging lenses.

Birefringence of single and bundled microtubules.

PubMed Central

Oldenbourg, R; Salmon, E D; Tran, P T

1998-01-01

We have measured the birefringence of microtubules (MTs) and of MT-based macromolecular assemblies in vitro and in living cells by using the new Pol-Scope. A single microtubule in aqueous suspension and imaged with a numerical aperture of 1.4 had a peak retardance of 0.07 nm. The peak retardance of a small bundle increased linearly with the number of MTs in the bundle. Axonemes (prepared from sea urchin sperm) had a peak retardance 20 times higher than that of single MTs, in accordance with the nine doublets and two singlets arrangement of parallel MTs in the axoneme. Measured filament retardance decreased when the filament was defocused or the numerical aperture of the imaging system was decreased. However, the retardance "area," which we defined as the image retardance integrated along a line perpendicular to the filament axis, proved to be independent of focus and of numerical aperture. These results are in good agreement with a theory that we developed for measuring retardances with imaging optics. Our theoretical concept is based on Wiener's theory of mixed dielectrics, which is well established for nonimaging applications. We extend its use to imaging systems by considering the coherence region defined by the optical set-up. Light scattered from within that region interferes coherently in the image point. The presence of a filament in the coherence region leads to a polarization dependent scattering cross section and to a finite retardance measured in the image point. Similar to resolution measurements, the linear dimension of the coherence region for retardance measurements is on the order lambda/(2 NA), where lambda is the wavelength of light and NA is the numerical aperture of the illumination and imaging lenses. PMID:9449366

Radiologic assessment of femoral and tibial tunnel placement based on anatomic landmarks in arthroscopic single bundle anterior cruciate ligament reconstruction

PubMed Central

Nema, Sandeep Kumar; Balaji, Gopisankar; Akkilagunta, Sujiv; Menon, Jagdish; Poduval, Murali; Patro, Dilip

2017-01-01

Background: Accurate tibial and femoral tunnel placement has a significant effect on outcomes after anterior cruciate ligament reconstruction (ACLR). Postoperative radiographs provide a reliable and valid way for the assessment of anatomical tunnel placement after ACLR. The aim of this study was to examine the radiographic location of tibial and femoral tunnels in patients who underwent arthroscopic ACLR using anatomic landmarks. Patients who underwent arthroscopic ACLR from January 2014 to March 2016 were included in this retrospective cohort study. Materials and Methods: 45 patients who underwent arthroscopic ACLR, postoperative radiographs were studied. Femoral and tibial tunnel positions on sagittal and coronal radiographic views, graft impingement, and femoral roof angle were measured. Radiological parameters were summarized as mean ± standard deviation and proportions as applicable. Interobserver agreement was measured using intraclass correlation coefficient. Results: The position of the tibial tunnel was found to be at an average of 35.1% ± 7.4% posterior from the anterior edge of the tibia. The femoral tunnel was found at an average of 30% ± 1% anterior to the posterior femoral cortex along the Blumensaat's line. Radiographic impingement was found in 34% of the patients. The roof angle averaged 34.3° ± 4.3°. The position of the tibial tunnel was found at an average of 44.16% ± 3.98% from the medial edge of the tibial plateau. The coronal tibial tunnel angle averaged 67.5° ± 8.9°. The coronal angle of the femoral tunnel averaged 41.9° ± 8.5°. Conclusions: The femoral and tibial tunnel placements correlated well with anatomic landmarks except for radiographic impingement which was present in 34% of the patients. PMID:28566780

Radiologic assessment of femoral and tibial tunnel placement based on anatomic landmarks in arthroscopic single bundle anterior cruciate ligament reconstruction.

PubMed

Nema, Sandeep Kumar; Balaji, Gopisankar; Akkilagunta, Sujiv; Menon, Jagdish; Poduval, Murali; Patro, Dilip

2017-01-01

Accurate tibial and femoral tunnel placement has a significant effect on outcomes after anterior cruciate ligament reconstruction (ACLR). Postoperative radiographs provide a reliable and valid way for the assessment of anatomical tunnel placement after ACLR. The aim of this study was to examine the radiographic location of tibial and femoral tunnels in patients who underwent arthroscopic ACLR using anatomic landmarks. Patients who underwent arthroscopic ACLR from January 2014 to March 2016 were included in this retrospective cohort study. 45 patients who underwent arthroscopic ACLR, postoperative radiographs were studied. Femoral and tibial tunnel positions on sagittal and coronal radiographic views, graft impingement, and femoral roof angle were measured. Radiological parameters were summarized as mean ± standard deviation and proportions as applicable. Interobserver agreement was measured using intraclass correlation coefficient. The position of the tibial tunnel was found to be at an average of 35.1% ± 7.4% posterior from the anterior edge of the tibia. The femoral tunnel was found at an average of 30% ± 1% anterior to the posterior femoral cortex along the Blumensaat's line. Radiographic impingement was found in 34% of the patients. The roof angle averaged 34.3° ± 4.3°. The position of the tibial tunnel was found at an average of 44.16% ± 3.98% from the medial edge of the tibial plateau. The coronal tibial tunnel angle averaged 67.5° ± 8.9°. The coronal angle of the femoral tunnel averaged 41.9° ± 8.5°. The femoral and tibial tunnel placements correlated well with anatomic landmarks except for radiographic impingement which was present in 34% of the patients.

Tibiofemoral Contact Forces in the Anterior Cruciate Ligament-Reconstructed Knee.

PubMed

Saxby, David John; Bryant, Adam L; Modenese, Luca; Gerus, Pauline; Killen, Bryce A; Konrath, Jason; Fortin, Karine; Wrigley, Tim V; Bennell, Kim L; Cicuttini, Flavia M; Vertullo, Christopher; Feller, Julian A; Whitehead, Tim; Gallie, Price; Lloyd, David G

2016-11-01

To investigate differences in anterior cruciate ligament-reconstructed (ACLR) and healthy individuals in terms of the magnitude of the tibiofemoral contact forces, as well as the relative muscle and external load contributions to those contact forces, during walking, running, and sidestepping gait tasks. A computational EMG-driven neuromusculoskeletal model was used to estimate the muscle and tibiofemoral contact forces in those with single-bundle combined semitendinosus and gracilis tendon autograft ACLR (n = 104, 29.7 ± 6.5 yr, 78.1 ± 14.4 kg) and healthy controls (n = 60, 27.5 ± 5.4 yr, 67.8 ± 14.0 kg) during walking (1.4 ± 0.2 m·s), running (4.5 ± 0.5 m·s) and sidestepping (3.7 ± 0.6 m·s). Within the computational model, the semitendinosus of ACLR participants was adjusted to account for literature reported strength deficits and morphological changes subsequent to autograft harvesting. ACLR had smaller maximum total and medial tibiofemoral contact forces (~80% of control values, scaled to bodyweight) during the different gait tasks. Compared with controls, ACLR were found to have a smaller maximum knee flexion moment, which explained the smaller tibiofemoral contact forces. Similarly, compared with controls, ACLR had both a smaller maximum knee flexion angle and knee flexion excursion during running and sidestepping, which may have concentrated the articular contact forces to smaller areas within the tibiofemoral joint. Mean relative muscle and external load contributions to the tibiofemoral contact forces were not significantly different between ACLR and controls. ACLR had lower bodyweight-scaled tibiofemoral contact forces during walking, running, and sidestepping, likely due to lower knee flexion moments and straighter knee during the different gait tasks. The relative contributions of muscles and external loads to the contact forces were equivalent between groups.

CO 2 Capture by Cold Membrane Operation with Actual Power Plant Flue Gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chaubey, Trapti; Kulkarni, Sudhir; Hasse, David

The main objective of the project was to develop a post-combustion CO 2 capture process based on the hybrid cold temperature membrane operation. The CO 2 in the flue gas from coal fired power plant is pre-concentrated to >60% CO 2 in the first stage membrane operation followed by further liquefaction of permeate stream to achieve >99% CO 2 purity. The aim of the project was based on DOE program goal of 90% CO 2 capture with >95% CO 2 purity from Pulverized Coal (PC) fired power plants with $40/tonne of carbon capture cost by 2025. The project moves themore » technology from TRL 4 to TRL 5. The project involved optimization of Air Liquide commercial 12” PI-1 bundle to improve the bundle productivity by >30% compared to the previous baseline (DE-FE0004278) using computational fluid dynamics (CFD) modeling and bundle testing with synthetic flue gas at 0.1 MWe bench scale skid located at Delaware Research and Technology Center (DRTC). In parallel, the next generation polyimide based novel PI-2 membrane was developed with 10 times CO 2 permeance compared to the commercial PI-1 membrane. The novel PI-2 membrane was scaled from mini-permeator to 1” permeator and 1” bundle for testing. Bundle development was conducted with a Development Spin Unit (DSU) installed at MEDAL. Air Liquide’s cold membrane technology was demonstrated with real coal fired flue gas at the National Carbon Capture Center (NCCC) with a 0.3 MWe field-test unit (FTU). The FTU was designed to incorporate testing of two PI-1 commercial membrane bundles (12” or 6” diameter) in parallel or series. A slip stream was sent to the next generation PI-2 membrane for testing with real flue gas. The system exceeded performance targets with stable PI-1 membrane operation for over 500 hours of single bundle, steady state testing. The 12” PI-1 bundle exceeded the productivity target by achieving ~600 Nm3/hr, where the target was set at ~455 Nm3/hr at 90% capture rate. The cost of 90% CO 2 capture from a 550 MWe net coal power plant was estimated between 40 and $45/tonne. A 6” PI-1 bundle exhibited superior bundle performance compared to the 12” PI-1 bundle. However, the carbon capture cost was not lower with the 6” PI-1 bundle due to the higher bundle installed cost. A 1” PI-1 bundle was tested to compare bundles with different length / diameter ratios. This bundle exhibited the lowest performance due to the different fiber winding pattern and increased bundle non-ideality. Several long-term and parametric tests were conducted with 3,200 hours of total run-time at NCCC. Finally, the new PI-2 membrane fiber was tested at a small scale (1” modules) in real flue gas and exhibited up to 10 times the CO 2 permeance and slightly lower CO 2/N 2 selectivity as the commercial PI-1 fiber. This corresponded to a projected 4 - 5 times increase in the productivity per bundle and a potential cost reduction of $3/tonne for CO2 capture, as compared with PI-1. An analytical campaign was conducted to trace different impurities such as NOx, mercury, Arsenic, Selenium in gas and liquid samples through the carbon capture system. An Environmental, Health and Safety (EH&S) analysis was completed to estimate emissions from a 550 MWe net power plant with carbon capture using cold membrane. A preliminary design and cost analysis was completed for 550 tpd (~25 MWe) plant to assess the capital investment and carbon capture cost for PI-1 and PI-2 membrane solutions from coal fired flue gas. A comparison was made with an amine based solution with significant cost advantage for the membrane at this scale. Additional preliminary design and cost analysis was completed between coal, natural gas and SMR flue gas for carbon capture at 550 tpd (~25 MWe) plant.« less

Line-Tension Controlled Mechanism for Influenza Fusion

PubMed Central

Risselada, Herre Jelger; Smirnova, Yuliya G.; Grubmüller, Helmut; Marrink, Siewert Jan; Müller, Marcus

2012-01-01

Our molecular simulations reveal that wild-type influenza fusion peptides are able to stabilize a highly fusogenic pre-fusion structure, i.e. a peptide bundle formed by four or more trans-membrane arranged fusion peptides. We rationalize that the lipid rim around such bundle has a non-vanishing rim energy (line-tension), which is essential to (i) stabilize the initial contact point between the fusing bilayers, i.e. the stalk, and (ii) drive its subsequent evolution. Such line-tension controlled fusion event does not proceed along the hypothesized standard stalk-hemifusion pathway. In modeled influenza fusion, single point mutations in the influenza fusion peptide either completely inhibit fusion (mutants G1V and W14A) or, intriguingly, specifically arrest fusion at a hemifusion state (mutant G1S). Our simulations demonstrate that, within a line-tension controlled fusion mechanism, these known point mutations either completely inhibit fusion by impairing the peptide’s ability to stabilize the required peptide bundle (G1V and W14A) or stabilize a persistent bundle that leads to a kinetically trapped hemifusion state (G1S). In addition, our results further suggest that the recently discovered leaky fusion mutant G13A, which is known to facilitate a pronounced leakage of the target membrane prior to lipid mixing, reduces the membrane integrity by forming a ‘super’ bundle. Our simulations offer a new interpretation for a number of experimentally observed features of the fusion reaction mediated by the prototypical fusion protein, influenza hemagglutinin, and might bring new insights into mechanisms of other viral fusion reactions. PMID:22761674

Fascin- and α-Actinin-Bundled Networks Contain Intrinsic Structural Features that Drive Protein Sorting.

PubMed

Winkelman, Jonathan D; Suarez, Cristian; Hocky, Glen M; Harker, Alyssa J; Morganthaler, Alisha N; Christensen, Jenna R; Voth, Gregory A; Bartles, James R; Kovar, David R

2016-10-24

Cells assemble and maintain functionally distinct actin cytoskeleton networks with various actin filament organizations and dynamics through the coordinated action of different sets of actin-binding proteins. The biochemical and functional properties of diverse actin-binding proteins, both alone and in combination, have been increasingly well studied. Conversely, how different sets of actin-binding proteins properly sort to distinct actin filament networks in the first place is not nearly as well understood. Actin-binding protein sorting is critical for the self-organization of diverse dynamic actin cytoskeleton networks within a common cytoplasm. Using in vitro reconstitution techniques including biomimetic assays and single-molecule multi-color total internal reflection fluorescence microscopy, we discovered that sorting of the prominent actin-bundling proteins fascin and α-actinin to distinct networks is an intrinsic behavior, free of complicated cellular signaling cascades. When mixed, fascin and α-actinin mutually exclude each other by promoting their own recruitment and inhibiting recruitment of the other, resulting in the formation of distinct fascin- or α-actinin-bundled domains. Subdiffraction-resolution light microscopy and negative-staining electron microscopy revealed that fascin domains are densely packed, whereas α-actinin domains consist of widely spaced parallel actin filaments. Importantly, other actin-binding proteins such as fimbrin and espin show high specificity between these two bundle types within the same reaction. Here we directly observe that fascin and α-actinin intrinsically segregate to discrete bundled domains that are specifically recognized by other actin-binding proteins. Copyright © 2016 Elsevier Ltd. All rights reserved.

Spatial Mapping of Structural and Connectional Imaging Data for the Developing Human Brain with Diffusion Tensor Imaging

PubMed Central

Ouyang, Austin; Jeon, Tina; Sunkin, Susan M.; Pletikos, Mihovil; Sedmak, Goran; Sestan, Nenad; Lein, Ed S.; Huang, Hao

2014-01-01

During human brain development from fetal stage to adulthood, the white matter (WM) tracts undergo dramatic changes. Diffusion tensor imaging (DTI), a widely used magnetic resonance imaging (MRI) modality, offers insight into the dynamic changes of WM fibers as these fibers can be noninvasively traced and three-dimensionally (3D) reconstructed with DTI tractography. The DTI and conventional T1 weighted MRI images also provide sufficient cortical anatomical details for mapping the cortical regions of interests (ROIs). In this paper, we described basic concepts and methods of DTI techniques that can be used to trace major WM tracts noninvasively from fetal brain of 14 postconceptional weeks (pcw) to adult brain. We applied these techniques to acquire DTI data and trace, reconstruct and visualize major WM tracts during development. After categorizing major WM fiber bundles into five unique functional tract groups, namely limbic, brain stem, projection, commissural and association tracts, we revealed formation and maturation of these 3D reconstructed WM tracts of the developing human brain. The structural and connectional imaging data offered by DTI provides the anatomical backbone of transcriptional atlas of the developing human brain. PMID:25448302

3D Reconstruction of Static Human Body with a Digital Camera

NASA Astrophysics Data System (ADS)

Remondino, Fabio

2003-01-01

Nowadays the interest in 3D reconstruction and modeling of real humans is one of the most challenging problems and a topic of great interest. The human models are used for movies, video games or ergonomics applications and they are usually created with 3D scanner devices. In this paper a new method to reconstruct the shape of a static human is presented. Our approach is based on photogrammetric techniques and uses a sequence of images acquired around a standing person with a digital still video camera or with a camcorder. First the images are calibrated and orientated using a bundle adjustment. After the establishment of a stable adjusted image block, an image matching process is performed between consecutive triplets of images. Finally the 3D coordinates of the matched points are computed with a mean accuracy of ca 2 mm by forward ray intersection. The obtained point cloud can then be triangulated to generate a surface model of the body or a virtual human model can be fitted to the recovered 3D data. Results of the 3D human point cloud with pixel color information are presented.

Finite-size polyelectrolyte bundles at thermodynamic equilibrium

NASA Astrophysics Data System (ADS)

Sayar, M.; Holm, C.

2007-01-01

We present the results of extensive computer simulations performed on solutions of monodisperse charged rod-like polyelectrolytes in the presence of trivalent counterions. To overcome energy barriers we used a combination of parallel tempering and hybrid Monte Carlo techniques. Our results show that for small values of the electrostatic interaction the solution mostly consists of dispersed single rods. The potential of mean force between the polyelectrolyte monomers yields an attractive interaction at short distances. For a range of larger values of the Bjerrum length, we find finite-size polyelectrolyte bundles at thermodynamic equilibrium. Further increase of the Bjerrum length eventually leads to phase separation and precipitation. We discuss the origin of the observed thermodynamic stability of the finite-size aggregates.

Reconstructing Cell Lineages from Single-Cell Gene Expression Data: A Pilot Study

DTIC Science & Technology

2016-08-30

Reconstructing cell lineages from single- cell gene expression data: a pilot study The goal of this pilot study is to develop novel mathematical...methods, by leveraging tools developed in the bifurcation theory, to infer the underlying cell -state dynamics from single- cell gene expression data. Our...proposed method contains two steps. The first step is to reconstruct the temporal order of the cells from gene expression data, whereas the second

Thrombocytogenesis by megakaryocyte; Interpretation by protoplatelet hypothesis

PubMed Central

KOSAKI, Goro; KAMBAYASHI, Junichi

2011-01-01

Serial transmission electron microscopy of human megakaryocytes (MKs) revealed their polyploidization and gradual maturation through consecutive transition in characteristics of various organelles and others. At the beginning of differentiation, MK with ploidy 32N, e.g., has 16 centrosomes in the cell center surrounded by 32N nucleus. Each bundle of microtubules (MTs) emanated from the respective centrosome supports and organizes 16 equally volumed cytoplasmic compartments which together compose one single 32N MK. During the differentiation, single centriole separated from the centriole pair, i.e., centrosome, migrates to the most periphery of the cell through MT bundle, corresponding to a half of the interphase array originated from one centrosome, supporting one “putative cytoplasmic compartment” (PCC). Platelet demarcation membrane (DM) is constructed on the boundary surface between neighbouring PCCs. Matured PCC, composing of a tandem array of platelet territories covered by a sheet of DM is designated as protoplatelet. Eventually, the rupture of MK results in release of platelets from protoplatelets. PMID:21558761

Dual CARS and SHG image acquisition scheme that combines single central fiber and multimode fiber bundle to collect and differentiate backward and forward generated photons

PubMed Central

Weng, Sheng; Chen, Xu; Xu, Xiaoyun; Wong, Kelvin K.; Wong, Stephen T. C.

2016-01-01

In coherent anti-Stokes Raman scattering (CARS) and second harmonic generation (SHG) imaging, backward and forward generated photons exhibit different image patterns and thus capture salient intrinsic information of tissues from different perspectives. However, they are often mixed in collection using traditional image acquisition methods and thus are hard to interpret. We developed a multimodal scheme using a single central fiber and multimode fiber bundle to simultaneously collect and differentiate images formed by these two types of photons and evaluated the scheme in an endomicroscopy prototype. The ratio of these photons collected was calculated for the characterization of tissue regions with strong or weak epi-photon generation while different image patterns of these photons at different tissue depths were revealed. This scheme provides a new approach to extract and integrate information captured by backward and forward generated photons in dual CARS/SHG imaging synergistically for biomedical applications. PMID:27375938

High pressure Raman spectroscopy of single-walled carbon nanotubes: Effect of chemical environment on individual nanotubes and the nanotube bundle

NASA Astrophysics Data System (ADS)

Proctor, John E.; Halsall, Matthew P.; Ghandour, Ahmad; Dunstan, David J.

2006-12-01

The pressure-induced tangential mode Raman peak shifts for single-walled carbon nanotubes (SWNTs) have been studied using a variety of different solvents as hydrostatic pressure-transmitting media. The variation in the nanotube response to hydrostatic pressure with different pressure transmitting media is evidence that the common solvents used are able to penetrate the interstitial spaces in the nanotube bundle. With hexane, we find the surprising result that the individual nanotubes appear unaffected by hydrostatic pressures (i.e. a flat Raman response) up to 0.7 GPa. Qualitatively similar results have been obtained with butanol. Following the approach of Amer et al. [J. Chem. Phys. 121 (2004) 2752], we speculate that this is due to the inability of SWNTs to adsorb some solvents onto their surface at lower pressures. We also find that the role of cohesive energy density in the solvent nanotube interaction is more complex than previously thought.

Effects of elasticity and geometry on the locomotion of a model bacterium

NASA Astrophysics Data System (ADS)

Nguyen, Frank; Graham, Michael

2017-11-01

The locomotion of flagellated bacteria in viscous fluid provides the blueprint for a number of micro-scale engineering applications. The elasticities of both the hook protein (connecting cell body and flagellum) and the flagella themselves play a key role in determining the stability of locomotion. We use a coarse-grained discretization of elastic flagella connected to a rigid cell body to examine trajectories and flow fields for free swimmers. We indeed find that hook and/or flagellar buckling occurs above a critical flexibility relative to the swimmer's torque input. This renders straight swimming ineffective, though not necessarily undesirable in practice. Simulations with multiple flagella show bundling may partially stabilize the buckling effect. For a single flagellum or single bundle, we define a parameter space of characteristic angles tracking the overall time-averaged shape of the swimmer while also delineating stability boundaries between different modes of buckling. Ultimately our results may provide insight on how swimmers move through complex environments and how to design microrobotic swimmers for specific applications. NHS, GERS.

Fluorescence detection of the movement of single KcsA subunits reveals cooperativity

PubMed Central

Blunck, Rikard; McGuire, Hugo; Hyde, H. Clark; Bezanilla, Francisco

2008-01-01

The prokaryotic KcsA channel is gated at the helical bundle crossing by intracellular protons and inactivates at the extracellular selectivity filter. The C-terminal transmembrane helix has to undergo a conformational change for potassium ions to access the central cavity. Whereas a partial opening of the tetrameric channel is suggested to be responsible for subconductance levels of ion channels, including KcsA, a cooperative opening of the 4 subunits is postulated as the final opening step. In this study, we used single-channel fluorescence spectroscopy of KcsA to directly observe the movement of each subunit and the temporal correlation between subunits. Purified KcsA channels labeled at the C terminus near the bundle crossing have been inserted into supported lipid bilayer, and the fluorescence traces analyzed by means of a cooperative or independent Markov model. The analysis revealed that the 4 subunits do not move fully independently but instead showed a certain degree of cooperativity. However, the 4 subunits do not simply open in 1 concerted step. PMID:19074286

Quantitative underwater 3D motion analysis using submerged video cameras: accuracy analysis and trajectory reconstruction.

PubMed

Silvatti, Amanda P; Cerveri, Pietro; Telles, Thiago; Dias, Fábio A S; Baroni, Guido; Barros, Ricardo M L

2013-01-01

In this study we aim at investigating the applicability of underwater 3D motion capture based on submerged video cameras in terms of 3D accuracy analysis and trajectory reconstruction. Static points with classical direct linear transform (DLT) solution, a moving wand with bundle adjustment and a moving 2D plate with Zhang's method were considered for camera calibration. As an example of the final application, we reconstructed the hand motion trajectories in different swimming styles and qualitatively compared this with Maglischo's model. Four highly trained male swimmers performed butterfly, breaststroke and freestyle tasks. The middle fingertip trajectories of both hands in the underwater phase were considered. The accuracy (mean absolute error) of the two calibration approaches (wand: 0.96 mm - 2D plate: 0.73 mm) was comparable to out of water results and highly superior to the classical DLT results (9.74 mm). Among all the swimmers, the hands' trajectories of the expert swimmer in the style were almost symmetric and in good agreement with Maglischo's model. The kinematic results highlight symmetry or asymmetry between the two hand sides, intra- and inter-subject variability in terms of the motion patterns and agreement or disagreement with the model. The two outcomes, calibration results and trajectory reconstruction, both move towards the quantitative 3D underwater motion analysis.

Regularized Dual Averaging Image Reconstruction for Full-Wave Ultrasound Computed Tomography.

PubMed

Matthews, Thomas P; Wang, Kun; Li, Cuiping; Duric, Neb; Anastasio, Mark A

2017-05-01

Ultrasound computed tomography (USCT) holds great promise for breast cancer screening. Waveform inversion-based image reconstruction methods account for higher order diffraction effects and can produce high-resolution USCT images, but are computationally demanding. Recently, a source encoding technique has been combined with stochastic gradient descent (SGD) to greatly reduce image reconstruction times. However, this method bundles the stochastic data fidelity term with the deterministic regularization term. This limitation can be overcome by replacing SGD with a structured optimization method, such as the regularized dual averaging method, that exploits knowledge of the composition of the cost function. In this paper, the dual averaging method is combined with source encoding techniques to improve the effectiveness of regularization while maintaining the reduced reconstruction times afforded by source encoding. It is demonstrated that each iteration can be decomposed into a gradient descent step based on the data fidelity term and a proximal update step corresponding to the regularization term. Furthermore, the regularization term is never explicitly differentiated, allowing nonsmooth regularization penalties to be naturally incorporated. The wave equation is solved by the use of a time-domain method. The effectiveness of this approach is demonstrated through computer simulation and experimental studies. The results suggest that the dual averaging method can produce images with less noise and comparable resolution to those obtained by the use of SGD.

Trends in Local Therapy Utilization and Cost for Early-Stage Breast Cancer in Older Women: Implications for Payment and Policy Reform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shirvani, Shervin M.; Department of Radiation Oncology, Banner MD Anderson Cancer Center, Gilbert, Arizona; Jiang, Jing

Purpose: Older women with early-stage disease constitute the most rapidly growing breast cancer demographic, yet it is not known which local therapy strategies are most favored by this population in the current era. Understanding utilization trends and cost of local therapy is important for informing the design of bundled payment models as payers migrate away from fee-for-service models. We therefore used the Surveillance, Epidemiology, and End Results Medicare database to determine patterns of care and costs for local therapy among older women with breast cancer. Methods and Materials: Treatment strategy and covariables were determined in 55,327 women age ≥66 withmore » Tis-T2N0-1M0 breast cancer who underwent local therapy between 2000 and 2008. Trends in local therapy were characterized using Joinpoint. Polychotomous logistic regression determined predictors of local therapy. The median aggregate cost over the first 24 months after diagnosis was determined from Medicare claims through 2010 and reported in 2014 dollars. Results: The median age was 75. Local therapy distribution was as follows: 27,896 (50.3%) lumpectomy with external beam radiation, 18,356 (33.1%) mastectomy alone, 6159 (11.1%) lumpectomy alone, 1488 (2.7%) mastectomy with reconstruction, and 1455 (2.6%) lumpectomy with brachytherapy. Mastectomy alone declined from 39.0% in 2000 to 28.2% in 2008, and the use of breast conserving local therapies rose from 58.7% to 68.2%. Mastectomy with reconstruction was more common among the youngest, healthiest patients, whereas mastectomy alone was more common among patients living in rural low-income regions. By 2008, the costs were $36,749 for lumpectomy with brachytherapy, $35,030 for mastectomy with reconstruction, $31,388 for lumpectomy with external beam radiation, $21,993 for mastectomy alone, and $19,287 for lumpectomy alone. Conclusions: The use of mastectomy alone in older women declined in favor of breast conserving strategies between 2000 and 2008. Using these cost estimates, price points for local therapy bundles can be constructed to incentivize the treatment strategies that confer the highest value.« less

Multi-fiber strains measured by micro-Raman spectroscopy: Principles and experiments

NASA Astrophysics Data System (ADS)

Lei, Zhenkun; Wang, Yunfeng; Qin, Fuyong; Qiu, Wei; Bai, Ruixiang; Chen, Xiaogang

2016-02-01

Based on widely used axial strain measurement method of Kevlar single fiber, an original theoretical model and measurement principle of application of micro-Raman spectroscopy to multi-fiber strains in a fiber bundle were established. The relationship between the nominal Raman shift of fiber bundle and the multi-fiber strains was deduced. The proposed principle for multi-fiber strains measurement is consistent with two special cases: single fiber deformation and multi-fiber deformation under equal strain. It is found experimentally that the distribution of Raman scattering intensity of a Kevlar 49 fiber as a function of distance between a fiber and the laser spot center follows a Gaussian function. Combining the Raman-shift/strain relationship of the Kevlar 49 single fiber and the uniaxial tension measured by micro-Raman spectroscopy, the Raman shift as a function of strain was obtained. Then the Raman peak at 1610 cm-1 for the Kevlar 49 fiber was fitted to a Lorentzian function and the FWHM showed a quadratic increase with the fiber strain. Finally, a dual-fiber tensile experiment was performed to verify the adequacy of the Raman technique for the measurement of multi-fiber strains.

The Graft Bending Angle Can Affect Early Graft Healing After Anterior Cruciate Ligament Reconstruction: In Vivo Analysis With 2 Years' Follow-up.

PubMed

Tashiro, Yasutaka; Gale, Tom; Sundaram, Vani; Nagai, Kanto; Irrgang, James J; Anderst, William; Nakashima, Yasuharu; Tashman, Scott; Fu, Freddie H

2017-07-01

A high graft bending angle (GBA) after anterior cruciate ligament (ACL) reconstruction has been suggested to cause stress on the graft. Nevertheless, evidence about its effect on graft healing in vivo is limited. The signal intensity on magnetic resonance imaging (MRI) would be higher in the proximal region of the ACL graft, and higher signals would be correlated to a higher GBA. Descriptive laboratory study. Anatomic single-bundle ACL reconstruction was performed on 24 patients (mean age, 20 ± 4 years) using the transportal technique. A quadriceps tendon autograft with a bone plug was harvested. To evaluate graft healing, the signal/noise quotient (SNQ) was measured in 3 regions of interest (ROIs) of the proximal, midsubstance, and distal ACL graft using high-resolution MRI (0.45 × 0.45 × 0.70 mm), with decreased signals suggesting improved healing. Dynamic knee motion was examined during treadmill walking and running to assess the in vivo GBA. The GBA was calculated from the 3-dimensional angle between the graft and femoral tunnel vectors at each motion frame, based on tibiofemoral kinematics determined from dynamic stereo X-ray analysis. Graft healing and GBAs were assessed at 6 and 24 months postoperatively. Repeated-measures analysis of variance was used to compare the SNQ in the 3 ROIs at 2 time points. Pearson correlations were used to analyze the relationship between the SNQ and mean GBA during 0% to 15% of the gait cycle. The SNQ of the ACL graft in the proximal region was significantly higher than in the midsubstance ( P = .022) and distal regions ( P < .001) at 6 months. The SNQ in the proximal region was highly correlated with the GBA during standing ( R = 0.64, P < .001), walking ( R = 0.65, P = .002), and running ( R = 0.54, P = .015) but not in the other regions. At 24 months, signals in the proximal and midsubstance regions decreased significantly compared with 6 months ( P < .001 and P = .008, respectively), with no difference across the graft area. The signal intensity was highest in the proximal region and lowest in the distal region of the reconstructed graft at 6 months postoperatively. A steep GBA was significantly correlated with high signal intensities of the proximal graft in this early period. A steep GBA may negatively affect proximal graft healing after ACL reconstruction.

Early development of the Drosophila brain: V. Pattern of postembryonic neuronal lineages expressing DE-cadherin.

PubMed

Dumstrei, Karin; Wang, Fay; Nassif, Claude; Hartenstein, Volker

2003-01-20

The Drosophila E-cadherin homolog, DE-cadherin, is expressed postembryonically by brain neuroblasts and their lineages of neurons ("secondary lineages"). DE-cadherin appears in neuroblasts as soon as they can be identified by their increase in size and then remains expressed uninterruptedly throughout larval life. DE-cadherin remains transiently expressed in the cell bodies and axons of neurons produced by neuroblast proliferation. In general, axons of neurons belonging to one lineage form tight bundles. The trajectories of these bundles are correlated with the location of the neuronal lineages to which they belong. Thus, axon bundles of lineages that are neighbors in the cortex travel parallel to each other and reach the neuropile at similar positions. It is, therefore, possible to assign coherent groups of neuroblasts and their lineages to the individual neuropile compartments and long axon tracts introduced in the accompanying articles (Nassif et al. [2003] J Comp Neurol 455:417-434; Younossi-Hartenstein et al. [2003] J Comp Neurol 455:435-450). In this study, we have reconstructed the pattern of secondary lineages and their projection in relationship to the compartments and Fasciclin II-positive long axon tracts. Based on topology and axonal trajectory, the lineages of the central brain can be subdivided into 11 groups that can be followed throughout successive larval stages. The map of larval lineages and their axonal projection will be important for future studies on postembryonic neurogenesis in Drosophila. It also lays a groundwork for investigating the role of DE-cadherin in larval brain development. Copyright 2002 Wiley-Liss, Inc.

Application of neuroanatomical features to tractography clustering.

PubMed

Wang, Qian; Yap, Pew-Thian; Wu, Guorong; Shen, Dinggang

2013-09-01

Diffusion tensor imaging allows unprecedented insight into brain neural connectivity in vivo by allowing reconstruction of neuronal tracts via captured patterns of water diffusion in white matter microstructures. However, tractography algorithms often output hundreds of thousands of fibers, rendering subsequent data analysis intractable. As a remedy, fiber clustering techniques are able to group fibers into dozens of bundles and thus facilitate analyses. Most existing fiber clustering methods rely on geometrical information of fibers, by viewing them as curves in 3D Euclidean space. The important neuroanatomical aspect of fibers, however, is ignored. In this article, the neuroanatomical information of each fiber is encapsulated in the associativity vector, which functions as the unique "fingerprint" of the fiber. Specifically, each entry in the associativity vector describes the relationship between the fiber and a certain anatomical ROI in a fuzzy manner. The value of the entry approaches 1 if the fiber is spatially related to the ROI at high confidence; on the contrary, the value drops closer to 0. The confidence of the ROI is calculated by diffusing the ROI according to the underlying fibers from tractography. In particular, we have adopted the fast marching method for simulation of ROI diffusion. Using the associativity vectors of fibers, we further model fibers as observations sampled from multivariate Gaussian mixtures in the feature space. To group all fibers into relevant major bundles, an expectation-maximization clustering approach is employed. Experimental results indicate that our method results in anatomically meaningful bundles that are highly consistent across subjects. Copyright © 2012 Wiley Periodicals, Inc., a Wiley company.

Crystal structure of bacterial cell-surface alginate-binding protein with an M75 peptidase motif

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maruyama, Yukie; Ochiai, Akihito; Mikami, Bunzo

Research highlights: {yields} Bacterial alginate-binding Algp7 is similar to component EfeO of Fe{sup 2+} transporter. {yields} We determined the crystal structure of Algp7 with a metal-binding motif. {yields} Algp7 consists of two helical bundles formed through duplication of a single bundle. {yields} A deep cleft involved in alginate binding locates around the metal-binding site. {yields} Algp7 may function as a Fe{sup 2+}-chelated alginate-binding protein. -- Abstract: A gram-negative Sphingomonas sp. A1 directly incorporates alginate polysaccharide into the cytoplasm via the cell-surface pit and ABC transporter. A cell-surface alginate-binding protein, Algp7, functions as a concentrator of the polysaccharide in the pit.more » Based on the primary structure and genetic organization in the bacterial genome, Algp7 was found to be homologous to an M75 peptidase motif-containing EfeO, a component of a ferrous ion transporter. Despite the presence of an M75 peptidase motif with high similarity, the Algp7 protein purified from recombinant Escherichia coli cells was inert on insulin B chain and N-benzoyl-Phe-Val-Arg-p-nitroanilide, both of which are substrates for a typical M75 peptidase, imelysin, from Pseudomonas aeruginosa. The X-ray crystallographic structure of Algp7 was determined at 2.10 A resolution by single-wavelength anomalous diffraction. Although a metal-binding motif, HxxE, conserved in zinc ion-dependent M75 peptidases is also found in Algp7, the crystal structure of Algp7 contains no metal even at the motif. The protein consists of two structurally similar up-and-down helical bundles as the basic scaffold. A deep cleft between the bundles is sufficiently large to accommodate macromolecules such as alginate polysaccharide. This is the first structural report on a bacterial cell-surface alginate-binding protein with an M75 peptidase motif.« less

Thermal Aspects of Using Alternative Nuclear Fuels in Supercritical Water-Cooled Reactors

NASA Astrophysics Data System (ADS)

Grande, Lisa Christine

A SuperCritical Water-cooled Nuclear Reactor (SCWR) is a Generation IV concept currently being developed worldwide. Unique to this reactor type is the use of light-water coolant above its critical point. The current research presents a thermal-hydraulic analysis of a single fuel channel within a Pressure Tube (PT)-type SCWR with a single-reheat cycle. Since this reactor is in its early design phase many fuel-channel components are being investigated in various combinations. Analysis inputs are: steam cycle, Axial Heat Flux Profile (AHFP), fuel-bundle geometry, and thermophysical properties of reactor coolant, fuel sheath and fuel. Uniform and non-uniform AHFPs for average channel power were applied to a variety of alternative fuels (mixed oxide, thorium dioxide, uranium dicarbide, uranium nitride and uranium carbide) enclosed in an Inconel-600 43-element bundle. The results depict bulk-fluid, outer-sheath and fuel-centreline temperature profiles together with the Heat Transfer Coefficient (HTC) profiles along the heated length of fuel channel. The objective is to identify the best options in terms of fuel, sheath material and AHFPS in which the outer-sheath and fuel-centreline temperatures will be below the accepted temperature limits of 850°C and 1850°C respectively. The 43-element Inconel-600 fuel bundle is suitable for SCWR use as the sheath-temperature design limit of 850°C was maintained for all analyzed cases at average channel power. Thoria, UC2, UN and UC fuels for all AHFPs are acceptable since the maximum fuel-centreline temperature does not exceed the industry accepted limit of 1850°C. Conversely, the fuel-centreline temperature limit was exceeded for MOX at all AHFPs, and UO2 for both cosine and downstream-skewed cosine AHFPs. Therefore, fuel-bundle modifications are required for UO2 and MOX to be feasible nuclear fuels for SCWRs.

Distribution and Determinants of 90-Day Payments for Multilevel Posterior Lumbar Fusion: A Medicare Analysis.

PubMed

Jain, Nikhil; Phillips, Frank M; Khan, Safdar N

2018-04-01

A retrospective, economic analysis. The objective of this article is to analyze the distribution of 90-day payments, sources of variation, and reimbursement for complications and readmissions for primary ≥3-level posterior lumbar fusion (PLF) from Medicare data. A secondary objective was to identify risk factors for complications. Bundled payments represent a single payment system to cover all costs associated with a single episode of care, typically over 90 days. The dollar amount spent on different health service providers and the variation in payments for ≥3-level PLF have not been analyzed from a bundled perspective. Administrative claims data were used to study 90-day Medicare (2005-2012) reimbursements for primary ≥3-level PLF for deformity and degenerative conditions of the lumbar spine. Distribution of payments, sources of variation, and reimbursements for managing complications were studied using linear regression models. Risk factors for complications were studied by stepwise multiple-variable logistic regression analysis. Hospital payments comprised 73.8% share of total 90-day payment. Adjusted analysis identified several factors for variation in index hospital payments. The average 90-day Medicare payment for all multilevel PLFs without complications was $35,878 per patient. The additional average cost of treating complications with/without revision surgery within 90 days period ranged from $17,284 to $68,963. A 90-day bundle for ≥3-level PLF with readmission ranges from $88,648 (3 levels) to $117,215 (8+ levels). Rates and risk factors for complications were also identified. The average 90-day payment per patient from Medicare was $35,878 with several factors such as levels of surgery, comorbidities, and development of complications influencing the cost. The study also identifies the risks and costs associated with complications and readmissions and emphasize the significant effect these would have on bundled payments (additional burden of up to 192% the cost of an average uncomplicated procedure over 90 days). Level 3.

Single-image-based Modelling Architecture from a Historical Photograph

NASA Astrophysics Data System (ADS)

Dzwierzynska, Jolanta

2017-10-01

Historical photographs are proved to be very useful to provide a dimensional and geometrical analysis of buildings as well as to generate 3D reconstruction of the whole structure. The paper addresses the problem of single historical photograph analysis and modelling of an architectural object from it. Especially, it focuses on reconstruction of the original look of New-Town synagogue from the single historic photograph, when camera calibration is completely unknown. Due to the fact that the photograph faithfully followed the geometric rules of perspective, it was possible to develop and apply the method to obtain a correct 3D reconstruction of the building. The modelling process consisted of a series of familiar steps: feature extraction, determination of base elements of perspective, dimensional analyses and 3D reconstruction. Simple formulas were proposed in order to estimate location of characteristic points of the building in 3D Cartesian system of axes on the base of their location in 2D Cartesian system of axes. The reconstruction process proceeded well, although slight corrections were necessary. It was possible to reconstruct the shape of the building in general, and two of its facades in detail. The reconstruction of the other two facades requires some additional information or the additional picture. The success of the presented reconstruction method depends on the geometrical content of the photograph as well as quality of the picture, which ensures the legibility of building edges. The presented method of reconstruction is a combination of the descriptive method of reconstruction and computer aid; therefore, it seems to be universal. It can prove useful for single-image-based modelling architecture.

Anatomy of the clitoris.

PubMed

O'Connell, Helen E; Sanjeevan, Kalavampara V; Hutson, John M

2005-10-01

We present a comprehensive account of clitoral anatomy, including its component structures, neurovascular supply, relationship to adjacent structures (the urethra, vagina and vestibular glands, and connective tissue supports), histology and immunohistochemistry. We related recent anatomical findings to the historical literature to determine when data on accurate anatomy became available. An extensive review of the current and historical literature was done. The studies reviewed included dissection and microdissection, magnetic resonance imaging (MRI), 3-dimensional sectional anatomy reconstruction, histology and immunohistochemical studies. The clitoris is a multiplanar structure with a broad attachment to the pubic arch and via extensive supporting tissue to the mons pubis and labia. Centrally it is attached to the urethra and vagina. Its components include the erectile bodies (paired bulbs and paired corpora, which are continuous with the crura) and the glans clitoris. The glans is a midline, densely neural, non-erectile structure that is the only external manifestation of the clitoris. All other components are composed of erectile tissue with the composition of the bulbar erectile tissue differing from that of the corpora. The clitoral and perineal neurovascular bundles are large, paired terminations of the pudendal neurovascular bundles. The clitoral neurovascular bundles ascend along the ischiopubic rami to meet each other and pass along the superior surface of the clitoral body supplying the clitoris. The neural trunks pass largely intact into the glans. These nerves are at least 2 mm in diameter even in infancy. The cavernous or autonomic neural anatomy is microscopic and difficult to define consistently. MRI complements dissection studies and clarifies the anatomy. Clitoral pharmacology and histology appears to parallel those of penile tissue, although the clinical impact is vastly different. Typical textbook descriptions of the clitoris lack detail and include inaccuracies. It is impossible to convey clitoral anatomy in a single diagram showing only 1 plane, as is typically provided in textbooks, which reveal it as a flat structure. MRI provides a multiplanar representation of clitoral anatomy in the live state, which is a major advantage, and complements dissection materials. The work of Kobelt in the early 19th century provides a most comprehensive and accurate description of clitoral anatomy, and modern study provides objective images and few novel findings. The bulbs appear to be part of the clitoris. They are spongy in character and in continuity with the other parts of the clitoris. The distal urethra and vagina are intimately related structures, although they are not erectile in character. They form a tissue cluster with the clitoris. This cluster appears to be the locus of female sexual function and orgasm.

Enrichment Mechanism of Semiconducting Single-walled Carbon Nanotubes by Surfactant Amines

PubMed Central

Ju, Sang-Yong; Utz, Marcel; Papadimitrakopoulos, Fotios

2009-01-01

Utilization of single-walled carbon nanotubes (SWNTs) in high-end applications hinges on separating metallic (met-) from semiconducting (sem-) SWNTs. Surfactant amines, like octadecylamine (ODA) have proven instrumental for the selective extraction of sem-SWNTs from tetrahydrofuran (THF) nanotube suspensions. The chemical shift differences along the tail of an asymmetric, diacetylenic surfactant amine were used to probe the molecular dynamics in the presence and absence of nanotubes via NMR. The results suggest that the surfactant amine head is firmly immobilized onto the nanotube surface together with acidic water, while the aliphatic tail progressively gains larger mobility as it gets farther from the SWNT. X-ray and high-resolution TEM studies indicate that the sem-enriched sample is populated mainly by small nanotube bundles containing ca. three SWNTs. Molecular simulations in conjunction with previously determined HNO3/H2SO4 oxidation depths for met- and sem-SWNTs indicate that the strong pinning of the amine surfactants on the sem-enriched SWNTs bundles is a result of a well-ordered arrangement of nitrate/amine salts separated with a monomolecular layer of H2O. Such continuous 2D arrangement of nitrate/amine salts shields the local environment adjacent to sem-enriched SWNTs bundles and maintains an acidic pH that preserves nanotube oxidation (i.e. SWNTn+). This, in turn, results in strong interactions with charge-balancing NO3- counter ions that through their association with neutralized surfactant amines provide effective THF dispersion and consequent sem-enrichment. PMID:19397291

Scaling of F-actin network rheology to probe single filament elasticity and dynamics.

PubMed

Gardel, M L; Shin, J H; MacKintosh, F C; Mahadevan, L; Matsudaira, P A; Weitz, D A

2004-10-29

The linear and nonlinear viscoelastic response of networks of cross-linked and bundled cytoskeletal filaments demonstrates remarkable scaling with both frequency and applied prestress, which helps elucidate the origins of the viscoelasticity. The frequency dependence of the shear modulus reflects the underlying single-filament relaxation dynamics for 0.1-10 rad/sec. Moreover, the nonlinear strain stiffening of such networks exhibits a universal form as a function of prestress; this is quantitatively explained by the full force-extension relation of single semiflexible filaments.

Computational representation of the aponeuroses as NURBS surfaces in 3D musculoskeletal models.

PubMed

Wu, Florence T H; Ng-Thow-Hing, Victor; Singh, Karan; Agur, Anne M; McKee, Nancy H

2007-11-01

Computational musculoskeletal (MSK) models - 3D graphics-based models that accurately simulate the anatomical architecture and/or the biomechanical behaviour of organ systems consisting of skeletal muscles, tendons, ligaments, cartilage and bones - are valued biomedical tools, with applications ranging from pathological diagnosis to surgical planning. However, current MSK models are often limited by their oversimplifications in anatomical geometries, sometimes lacking discrete representations of connective tissue components entirely, which ultimately affect their accuracy in biomechanical simulation. In particular, the aponeuroses - the flattened fibrous connective sheets connecting muscle fibres to tendons - have never been geometrically modeled. The initiative was thus to extend Anatomy3D - a previously developed software bundle for reconstructing muscle fibre architecture - to incorporate aponeurosis-modeling capacity. Two different algorithms for aponeurosis reconstruction were written in the MEL scripting language of the animation software Maya 6.0, using its NURBS (non-uniform rational B-splines) modeling functionality for aponeurosis surface representation. Both algorithms were validated qualitatively against anatomical and functional criteria.

Nanostructured optical fibre arrays for high-density biochemical sensing and remote imaging.

PubMed

Deiss, F; Sojic, N; White, D J; Stoddart, P R

2010-01-01

Optical fibre bundles usually comprise a few thousand to tens of thousands of individually clad glass optical fibres. The ordered arrangement of the fibres enables coherent transmission of an image through the bundle and therefore enables analysis and viewing in remote locations. In fused bundles, this architecture has also been used to fabricate arrays of various micro to nano-scale surface structures (micro/nanowells, nanotips, triangles, etc.) over relatively large areas. These surface structures have been used to obtain new optical and analytical capabilities. Indeed, the imaging bundle can be thought of as a "starting material" that can be sculpted by a combination of fibre drawing and selective wet-chemical etching processes. A large variety of bioanalytical applications have thus been developed, ranging from nano-optics to DNA nanoarrays. For instance, nanostructured optical surfaces with intrinsic light-guiding properties have been exploited as surface-enhanced Raman scattering (SERS) platforms and as near-field probe arrays. They have also been productively associated with electrochemistry to fabricate arrays of transparent nanoelectrodes with electrochemiluminescent imaging properties. The confined geometry of the wells has been loaded with biosensing materials and used as femtolitre-sized vessels to detect single molecules. This review describes the fabrication of high-density nanostructured optical fibre arrays and summarizes the large range of optical and bioanalytical applications that have been developed, reflecting the versatility of this ordered light-guiding platform.

A Jones matrix formalism for simulating three-dimensional polarized light imaging of brain tissue.

PubMed

Menzel, M; Michielsen, K; De Raedt, H; Reckfort, J; Amunts, K; Axer, M

2015-10-06

The neuroimaging technique three-dimensional polarized light imaging (3D-PLI) provides a high-resolution reconstruction of nerve fibres in human post-mortem brains. The orientations of the fibres are derived from birefringence measurements of histological brain sections assuming that the nerve fibres—consisting of an axon and a surrounding myelin sheath—are uniaxial birefringent and that the measured optic axis is oriented in the direction of the nerve fibres (macroscopic model). Although experimental studies support this assumption, the molecular structure of the myelin sheath suggests that the birefringence of a nerve fibre can be described more precisely by multiple optic axes oriented radially around the fibre axis (microscopic model). In this paper, we compare the use of the macroscopic and the microscopic model for simulating 3D-PLI by means of the Jones matrix formalism. The simulations show that the macroscopic model ensures a reliable estimation of the fibre orientations as long as the polarimeter does not resolve structures smaller than the diameter of single fibres. In the case of fibre bundles, polarimeters with even higher resolutions can be used without losing reliability. When taking the myelin density into account, the derived fibre orientations are considerably improved. © 2015 The Author(s).

On the properties of a bundle of flexible actin filaments in an optical trap

NASA Astrophysics Data System (ADS)

Perilli, Alessia; Pierleoni, Carlo; Ciccotti, Giovanni; Ryckaert, Jean-Paul

2016-06-01

We establish the statistical mechanics framework for a bundle of Nf living and uncrosslinked actin filaments in a supercritical solution of free monomers pressing against a mobile wall. The filaments are anchored normally to a fixed planar surface at one of their ends and, because of their limited flexibility, they grow almost parallel to each other. Their growing ends hit a moving obstacle, depicted as a second planar wall, parallel to the previous one and subjected to a harmonic compressive force. The force constant is denoted as the trap strength while the distance between the two walls as the trap length to make contact with the experimental optical trap apparatus. For an ideal solution of reactive filaments and free monomers at fixed free monomer chemical potential μ1, we obtain the general expression for the grand potential from which we derive averages and distributions of relevant physical quantities, namely, the obstacle position, the bundle polymerization force, and the number of filaments in direct contact with the wall. The grafted living filaments are modeled as discrete Wormlike chains, with F-actin persistence length ℓp, subject to discrete contour length variations ±d (the monomer size) to model single monomer (de)polymerization steps. Rigid filaments (ℓp = ∞), either isolated or in bundles, all provide average values of the stalling force in agreement with Hill's predictions Fs H = N f k B T ln ( ρ 1 / ρ 1 c) / d , independent of the average trap length. Here ρ1 is the density of free monomers in the solution and ρ1c its critical value at which the filament does not grow nor shrink in the absence of external forces. Flexible filaments (ℓp < ∞) instead, for values of the trap strength suitable to prevent their lateral escape, provide an average bundle force and an average trap length slightly larger than the corresponding rigid cases (few percents). Still the stalling force remains nearly independent on the average trap length, but results from the product of two strongly L-dependent contributions: the fraction of touching filaments ∝ (" separators=" < L >O . T .) 2 and the single filament buckling force ∝ (" separators=" < L >O . T .) - 2 .

Fast Automatic Segmentation of White Matter Streamlines Based on a Multi-Subject Bundle Atlas.

PubMed

Labra, Nicole; Guevara, Pamela; Duclap, Delphine; Houenou, Josselin; Poupon, Cyril; Mangin, Jean-François; Figueroa, Miguel

2017-01-01

This paper presents an algorithm for fast segmentation of white matter bundles from massive dMRI tractography datasets using a multisubject atlas. We use a distance metric to compare streamlines in a subject dataset to labeled centroids in the atlas, and label them using a per-bundle configurable threshold. In order to reduce segmentation time, the algorithm first preprocesses the data using a simplified distance metric to rapidly discard candidate streamlines in multiple stages, while guaranteeing that no false negatives are produced. The smaller set of remaining streamlines is then segmented using the original metric, thus eliminating any false positives from the preprocessing stage. As a result, a single-thread implementation of the algorithm can segment a dataset of almost 9 million streamlines in less than 6 minutes. Moreover, parallel versions of our algorithm for multicore processors and graphics processing units further reduce the segmentation time to less than 22 seconds and to 5 seconds, respectively. This performance enables the use of the algorithm in truly interactive applications for visualization, analysis, and segmentation of large white matter tractography datasets.

Magnetic resonance imaging reveals functional anatomy and biomechanics of a living dragon tree

PubMed Central

Hesse, Linnea; Masselter, Tom; Leupold, Jochen; Spengler, Nils; Speck, Thomas; Korvink, Jan Gerrit

2016-01-01

Magnetic resonance imaging (MRI) was used to gain in vivo insight into load-induced displacements of inner plant tissues making a non-invasive and non-destructive stress and strain analysis possible. The central aim of this study was the identification of a possible load-adapted orientation of the vascular bundles and their fibre caps as the mechanically relevant tissue in branch-stem-attachments of Dracaena marginata. The complex three-dimensional deformations that occur during mechanical loading can be analysed on the basis of quasi-three-dimensional data representations of the outer surface, the inner tissue arrangement (meristem and vascular system), and the course of single vascular bundles within the branch-stem-attachment region. In addition, deformations of vascular bundles could be quantified manually and by using digital image correlation software. This combination of qualitative and quantitative stress and strain analysis leads to an improved understanding of the functional morphology and biomechanics of D. marginata, a plant that is used as a model organism for optimizing branched technical fibre-reinforced lightweight trusses in order to increase their load bearing capacity. PMID:27604526

Local gene therapy durably restores vestibular function in a mouse model of Usher syndrome type 1G.

PubMed

Emptoz, Alice; Michel, Vincent; Lelli, Andrea; Akil, Omar; Boutet de Monvel, Jacques; Lahlou, Ghizlene; Meyer, Anaïs; Dupont, Typhaine; Nouaille, Sylvie; Ey, Elody; Franca de Barros, Filipa; Beraneck, Mathieu; Dulon, Didier; Hardelin, Jean-Pierre; Lustig, Lawrence; Avan, Paul; Petit, Christine; Safieddine, Saaid

2017-09-05

Our understanding of the mechanisms underlying inherited forms of inner ear deficits has considerably improved during the past 20 y, but we are still far from curative treatments. We investigated gene replacement as a strategy for restoring inner ear functions in a mouse model of Usher syndrome type 1G, characterized by congenital profound deafness and balance disorders. These mice lack the scaffold protein sans, which is involved both in the morphogenesis of the stereociliary bundle, the sensory antenna of inner ear hair cells, and in the mechanoelectrical transduction process. We show that a single delivery of the sans cDNA by the adenoassociated virus 8 to the inner ear of newborn mutant mice reestablishes the expression and targeting of the protein to the tips of stereocilia. The therapeutic gene restores the architecture and mechanosensitivity of stereociliary bundles, improves hearing thresholds, and durably rescues these mice from the balance defects. Our results open up new perspectives for efficient gene therapy of cochlear and vestibular disorders by showing that even severe dysmorphogenesis of stereociliary bundles can be corrected.

Xyloside primed glycosaminoglycans alter hair bundle micromechanical coupling and synaptic transmission: Pharmacokinetics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holman, Holly A.; Nguyen, Lynn Y.; Tran, Vy M.

Glycosaminoglycans (GAGs) are ubiquitous in the inner ear, and disorders altering their structure or production often result in debilitating hearing and balance deficits. The specific mechanisms responsible for loss of hair-cell function are not well understood. We recently reported that introduction of a novel BODIPY conjugated xyloside (BX) into the endolymph primes fluorescent GAGs in vivo [6, 15]. Confocal and two-photon fluorescence imaging revealed rapid turnover and assembly of a glycocalyx enveloping the kinocilia and extending into the cupula, a structure that presumably serves as a mechanical link between the hair bundle and the cupula. Extracellular fluorescence was also observedmore » around the basolateral surface of hair cells and surrounding afferent nerve projections into the crista. Single unit afferent recordings during mechanical hair bundle stimulation revealed temporary interruption of synaptic transmission following BX administration followed by recovery, demonstrating an essential role for GAGs in function of the hair cell synapse. In the present work we present a pharmacokinetic model to quantify the time course of BX primed GAG production and turnover in the ear.« less

Numerical Study on Influence of Cross Flow on Rewetting of AHWR Fuel Bundle

PubMed Central

Kumar, Mithilesh; Mukhopadhyay, D.; Ghosh, A. K.; Kumar, Ravi

2014-01-01

Numerical study on AHWR fuel bundle has been carried out to assess influence of circumferential and cross flow rewetting on the conduction heat transfer. The AHWR fuel bundle quenching under accident condition is designed primarily with radial jets at several axial locations. A 3D (r, θ, z) transient conduction fuel pin model has been developed to carry out the study with a finite difference method (FDM) technique with alternating direction implicit (ADI) scheme. The single pin has been considered to study effect of circumferential conduction and multipins have been considered to study the influence of cross flow. Both analyses are carried out with the same fluid temperature and heat transfer coefficients as boundary conditions. It has been found from the analyses that, for radial jet, the circumferential conduction is significant and due to influence of overall cross flow the reductions in fuel temperature in the same quench plane in different rings are different with same initial surface temperature. Influence of cross flow on rewetting is found to be very significant. Outer fuel pins rewetting time is higher than inner. PMID:24672341

Xyloside primed glycosaminoglycans alter hair bundle micromechanical coupling and synaptic transmission: Pharmacokinetics

NASA Astrophysics Data System (ADS)

Holman, Holly A.; Tran, Vy M.; Nguyen, Lynn Y.; Arungundram, Sailaja; Kalita, Mausam; Kuberan, Balagurunathan; Rabbitt, Richard D.

2015-12-01

Glycosaminoglycans (GAGs) are ubiquitous in the inner ear, and disorders altering their structure or production often result in debilitating hearing and balance deficits. The specific mechanisms responsible for loss of hair-cell function are not well understood. We recently reported that introduction of a novel BODIPY conjugated xyloside (BX) into the endolymph primes fluorescent GAGs in vivo [6, 15]. Confocal and two-photon fluorescence imaging revealed rapid turnover and assembly of a glycocalyx enveloping the kinocilia and extending into the cupula, a structure that presumably serves as a mechanical link between the hair bundle and the cupula. Extracellular fluorescence was also observed around the basolateral surface of hair cells and surrounding afferent nerve projections into the crista. Single unit afferent recordings during mechanical hair bundle stimulation revealed temporary interruption of synaptic transmission following BX administration followed by recovery, demonstrating an essential role for GAGs in function of the hair cell synapse. In the present work we present a pharmacokinetic model to quantify the time course of BX primed GAG production and turnover in the ear.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steelman, K L; Rowe, M W; Turpin, S A

Plasma oxidation was used to obtain radiocarbon dates on six different materials from a naturally mummified baby bundle from the Lower Pecos River region of southwest Texas. This bundle was selected because it was thought to represent a single event and would illustrate the accuracy and precision of the plasma oxidation method. Five of the materials were clearly components of the original bundle with 13 dates combined to yield a weighted average of 2135 {+-} 11 B.P. Six dates from a wooden stick of Desert Ash averaged 939 {+-} 14 B.P., indicating that this artifact was not part of themore » original burial. Plasma oxidation is shown to be a virtually non-destructive alternative to combustion. Because only sub-milligram amounts of material are removed from an artifact over its exposed surface, no visible change in fragile materials has been observed, even under magnification. The method is best applied when natural organic contamination is unlikely and serious consideration of this issue is needed in all cases. If organic contamination is present, it will have to be removed before plasma oxidation to obtain accurate radiocarbon dates.« less

The Morphosyntax of Discontinuous Exponence

ERIC Educational Resources Information Center

Campbell, Amy Melissa

2012-01-01

This thesis offers a systematic treatment of discontinuous exponence, a pattern of inflection in which a single feature or a set of features bundled in syntax is expressed by multiple, distinct morphemes. This pattern is interesting and theoretically relevant because it represents a deviation from the expected one-to-one relationship between…

Risks to the Superior Gluteal Neurovascular Bundle During Iliosacral and Transsacral Screw Fixation: A Computed Tomogram Arteriography Study.

PubMed

Maslow, Jed; Collinge, Cory A

2017-12-01

Iliosacral (IS) and transsacral (TS) screws are popular techniques to repair complicated injuries to the pelvis. The anatomy of the superior gluteal neurovasculature (SG NV bundle) is well described as running along the posterior ilium, providing innervation and perfusion to important abductor muscles. The method of pelvis fixation least likely to injure the SG NV bundle is unknown. Twenty uninjured patients with a contrasted computed tomogram of the pelvis and lower extremities (CTA) were evaluated. Starting points for an S1 IS screw and S1 and S2 TS screws were estimated on the "ghost" lateral CTA image for those pelvi with safe corridors (>9 mm diameter). The distance from the projected screw to the SG artery was measured. A distance of <3.65 mm (half of a 7.3-mm screw's diameter) was considered likely for NV bundle injury. Of 40 pelvi CTAs (single sides), 10 pelvi (25%) were determined to be inappropriate for an S1 TS screw. The average distances from the screw starting point and the artery were 25.3 mm (±9.2) for S1 IS, 12.4 mm (±9.0) for S1 TS, and 23.5 mm (±10.7) for S2 TS screws, respectively. Ten S1 TS screws (25%) and no S1 IS or S2 TS screws were projected to have caused injury to the SG NV bundle (P < 0.001). Inserting S1 IS and S2 TS screws put the SG NV anatomy at significantly less risk than S1 TS screws. This information may aid in choosing the "best" fixation option for patients with pelvic ring trauma requiring surgery.

On the force-velocity relationship of a bundle of rigid bio-filaments

NASA Astrophysics Data System (ADS)

Perilli, Alessia; Pierleoni, Carlo; Ciccotti, Giovanni; Ryckaert, Jean-Paul

2018-03-01

In various cellular processes, bio-filaments like F-actin and F-tubulin are able to exploit chemical energy associated with polymerization to perform mechanical work against an obstacle loaded with an external force. The force-velocity relationship quantitatively summarizes the nature of this process. By a stochastic dynamical model, we give, together with the evolution of a staggered bundle of Nf rigid living filaments facing a loaded wall, the corresponding force-velocity relationship. We compute the evolution of the model in the infinite wall diffusion limit and in supercritical conditions (monomer density reduced by critical density ρ^ 1>1 ), and we show that this solution remains valid for moderate non-zero values of the ratio between the wall diffusion and the chemical time scales. We consider two classical protocols: the bundle is opposed either to a constant load or to an optical trap setup, characterized by a harmonic restoring force. The constant load case leads, for each F value, to a stationary velocity Vs t a t(F ;Nf,ρ^ 1 ) after a relaxation with characteristic time τmicro(F). When the bundle (initially taken as an assembly of filament seeds) is subjected to a harmonic restoring force (optical trap load), the bundle elongates and the load increases up to stalling over a characteristic time τOT. Extracted from this single experiment, the force-velocity VO T(F ;Nf,ρ^ 1 ) curve is found to coincide with Vs t a t(F ;Nf,ρ^ 1 ) , except at low loads. We show that this result follows from the adiabatic separation between τmicro and τOT, i.e., τmicro ≪ τOT.

Combining food type(s) and food quantity choice in a new food choice paradigm based on vice-virtue bundles.

PubMed

Haws, Kelly L; Liu, Peggy J

2016-08-01

Given the prevalence and rising rates of obesity in many countries, including the United States, much food decision-making research ultimately aims at understanding how consumers can make healthier choices. The two predominant choice paradigms used in food decision-making research ask consumers to choose (a) between a "vice" (or unhealthy food) and a "virtue" (or healthy food) or (b) among varying portion sizes of "vice." We propose a new food choice paradigm that encourages consumers to jointly consider both food type(s) choice and food portion size at each decision point. The purpose of this paradigm is two-fold. First, it aims to allow examination of more comprehensive eating behavior (e.g., to examine the overall composition of a plate of food rather than choice of a single food). Second, it aims to shift consumers towards including large proportions of virtues and smaller proportions of vice in their overall consumption portfolios. For this paradigm, we draw upon a recently introduced food product innovation called "vice-virtue bundles" (Liu et al., 2015) that illustrates the basis of this new food choice paradigm, in which food type(s) and portion decisions are made simultaneously. Accordingly, we first discuss relevant findings on vice-virtue bundles as well as the differences between simultaneous and sequential choice of multiple products. Second, we examine the benefits for managing and controlling one's consumption that are provided by vice-virtue bundles and this joint food choice paradigm more generally. Third and finally, we point out opportunities for future research by discussing (a) multiple factors that influence food choices, (b) decision processes affected by food choice paradigms, and (c) issues of generalizability related to the presence of vice-virtue bundles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Compactly supported Wannier functions and algebraic K -theory

NASA Astrophysics Data System (ADS)

Read, N.

2017-03-01

In a tight-binding lattice model with n orbitals (single-particle states) per site, Wannier functions are n -component vector functions of position that fall off rapidly away from some location, and such that a set of them in some sense span all states in a given energy band or set of bands; compactly supported Wannier functions are such functions that vanish outside a bounded region. They arise not only in band theory, but also in connection with tensor-network states for noninteracting fermion systems, and for flat-band Hamiltonians with strictly short-range hopping matrix elements. In earlier work, it was proved that for general complex band structures (vector bundles) or general complex Hamiltonians—that is, class A in the tenfold classification of Hamiltonians and band structures—a set of compactly supported Wannier functions can span the vector bundle only if the bundle is topologically trivial, in any dimension d of space, even when use of an overcomplete set of such functions is permitted. This implied that, for a free-fermion tensor network state with a nontrivial bundle in class A, any strictly short-range parent Hamiltonian must be gapless. Here, this result is extended to all ten symmetry classes of band structures without additional crystallographic symmetries, with the result that in general the nontrivial bundles that can arise from compactly supported Wannier-type functions are those that may possess, in each of d directions, the nontrivial winding that can occur in the same symmetry class in one dimension, but nothing else. The results are obtained from a very natural usage of algebraic K -theory, based on a ring of polynomials in e±i kx,e±i ky,..., which occur as entries in the Fourier-transformed Wannier functions.

Remote fluorescence imaging of dynamic concentration profiles with micrometer resolution using a coherent optical fiber bundle.

PubMed

Amatore, Christian; Chovin, Arnaud; Garrigue, Patrick; Servant, Laurent; Sojic, Neso; Szunerits, Sabine; Thouin, Laurent

2004-12-15

Dynamic concentration profiles within the diffusion layer of an electrode were imaged in situ using fluorescence detection through a multichannel imaging fiber. In this work, a coherent optical fiber bundle is positioned orthogonal to the surface of an electrode and is used to report spatial and temporal micrometric changes in the fluorescence intensity of an initial fluorescent species. The fluorescence signal is directly related to the local concentration of a redox fluorescent reagent, which is electrochemically modulated by the electrode. Fluorescence images are collected through the optical fiber bundle during the oxidation of tris(2,2'-bipyridine)ruthenium(II) to ruthenium(III) at a diffusion-limited rate and allow the concentration profiles of Ru(II) reagent to be monitored in situ as a function of time. Tris(2,2'-bipyridine)ruthenium(II) is excited at 485 nm and emits fluorescence at 605 nm, whereas the Ru(III) oxidation state is not fluorescent. Our experiments emphasize the influence of two parameters on the micrometer spatial resolution: the numerical aperture of optical fibers within the bundle and the Ru(II) bulk concentration. The extent of the volume probed by each individual fiber of the bundle is discussed qualitatively in terms of a primary inner-filter effect and refractive index gradient. Experimentally measured fluorescence intensity profiles were found to be in very good agreement with concentration profiles predicted upon considering planar diffusion and thus validate the concept of this new application of imaging fibers. The originality of this remote approach is to provide a global view of the entire diffusion layer at a given time through one single image and to allow the time expansion of the diffusion layer to be followed quantitatively in real time.

Magnetic Resonance-Based Electrical Property Tomography (MR- EPT) for Prostate Cancer Grade Imaging

DTIC Science & Technology

2014-07-01

TV 2D 5 10 15 2 4 6 8 10 12 14 i 5 10 15 2 4 6 8 10 12 14 Figure 10. Prostate-like gelatin phantom with one inclusion (5mm, play dough ...magnitude image (TSE) and reconstructions. 11 c) Multiple Inclusions Two 5 mm diameter inclusions ( play dough to provide significant conductivity...reconstruction, 2D inverse reconstruction with Total Variation, 3D inverse reconstruction 10 b) Single inclusion A single 5 mm diameter inclusion ( play

Dynamical boson stars.

PubMed

Liebling, Steven L; Palenzuela, Carlos

2017-01-01

The idea of stable, localized bundles of energy has strong appeal as a model for particles. In the 1950s, John Wheeler envisioned such bundles as smooth configurations of electromagnetic energy that he called geons , but none were found. Instead, particle-like solutions were found in the late 1960s with the addition of a scalar field, and these were given the name boson stars . Since then, boson stars find use in a wide variety of models as sources of dark matter, as black hole mimickers, in simple models of binary systems, and as a tool in finding black holes in higher dimensions with only a single Killing vector. We discuss important varieties of boson stars, their dynamic properties, and some of their uses, concentrating on recent efforts.

Microscopy with multimode fibers

NASA Astrophysics Data System (ADS)

Moser, Christophe; Papadopoulos, Ioannis; Farahi, Salma; Psaltis, Demetri

2013-04-01

Microscopes are usually thought of comprising imaging elements such as objectives and eye-piece lenses. A different type of microscope, used for endoscopy, consists of waveguiding elements such as fiber bundles, where each fiber in the bundle transports the light corresponding to one pixel in the image. Recently a new type of microscope has emerged that exploits the large number of propagating modes in a single multimode fiber. We have successfully produced fluorescence images of neural cells with sub-micrometer resolution via a 200 micrometer core multimode fiber. The method for achieving imaging consists of using digital phase conjugation to reproduce a focal spot at the tip of the multimode fiber. The image is formed by scanning the focal spot digitally and collecting the fluorescence point by point.

Connecting the dots across time: reconstruction of single-cell signalling trajectories using time-stamped data

NASA Astrophysics Data System (ADS)

Mukherjee, Sayak; Stewart, David; Stewart, William; Lanier, Lewis L.; Das, Jayajit

2017-08-01

Single-cell responses are shaped by the geometry of signalling kinetic trajectories carved in a multidimensional space spanned by signalling protein abundances. It is, however, challenging to assay a large number (more than 3) of signalling species in live-cell imaging, which makes it difficult to probe single-cell signalling kinetic trajectories in large dimensions. Flow and mass cytometry techniques can measure a large number (4 to more than 40) of signalling species but are unable to track single cells. Thus, cytometry experiments provide detailed time-stamped snapshots of single-cell signalling kinetics. Is it possible to use the time-stamped cytometry data to reconstruct single-cell signalling trajectories? Borrowing concepts of conserved and slow variables from non-equilibrium statistical physics we develop an approach to reconstruct signalling trajectories using snapshot data by creating new variables that remain invariant or vary slowly during the signalling kinetics. We apply this approach to reconstruct trajectories using snapshot data obtained from in silico simulations, live-cell imaging measurements, and, synthetic flow cytometry datasets. The application of invariants and slow variables to reconstruct trajectories provides a radically different way to track objects using snapshot data. The approach is likely to have implications for solving matching problems in a wide range of disciplines.

Immediate Implant-based Prepectoral Breast Reconstruction Using a Vertical Incision

PubMed Central

Lind, Jeffrey G.; Hopkins, Elizabeth G.

2015-01-01

Background: Ideally, breast reconstruction is performed at the time of mastectomy in a single stage with minimal scarring. However, postoperative complications with direct-to-implant subpectoral reconstruction remain significant. These include asymmetry, flap necrosis, animation deformity, and discomfort. We report on a series of patients who have undergone immediate single-stage prepectoral, implant-based breast reconstruction with a smooth, adjustable saline implant covered with mesh/acellular dermal matrix for support using a vertical mastectomy incision. This technique, when combined with an adjustable implant, addresses the complications related to subpectoral implant placement of traditional expanders. Our follow-up time, 4.6 years (55 months), shows a low risk of implant loss and elimination of animation deformity while also providing patients with a safe and aesthetically pleasing result. Methods: All patients who underwent immediate implant-based prepectoral breast reconstruction using a vertical mastectomy incision as a single-staged procedure were included. Charts were reviewed retrospectively. Adjustable smooth round saline implants and mesh/acellular dermal matrix were used for fixation in all cases. Results: Thirty-one patients (62 breasts) underwent single-staged implant-based prepectoral breast reconstruction using a vertical mastectomy incision. Postoperative complications occurred in 9 patients, 6 of which were resolved with postoperative intervention while only 2 cases resulted in implant loss. Conclusions: There can be significant morbidity associated with traditional subpectoral implant-based breast reconstruction. As an alternative, the results of this study show that an immediate single-stage prepectoral breast reconstruction with a smooth saline adjustable implant, using a vertical incision, in conjunction with mesh/matrix support can be performed with excellent aesthetic outcomes and minimal complications. PMID:26180713

Single-legged Hop Tests as Predictors of Self-reported Knee Function After Anterior Cruciate Ligament Reconstruction

PubMed Central

Logerstedt, David; Grindem, Hege; Lynch, Andrew; Eitzen, Ingrid; Engebretsen, Lars; Risberg, May Arna; Axe, Michael J.; Snyder-Mackler, Lynn

2012-01-01

Background Single-legged hop tests are commonly used functional performance measures that can capture limb asymmetries in patients after anterior cruciate ligament (ACL) reconstruction. Hop tests hold potential as predictive factors of self-reported knee function in individuals after ACL reconstruction. Hypothesis Single-legged hop tests conducted preoperatively would not and 6 months after ACL reconstruction would predict self-reported knee function (International Knee Documentation Committee [IKDC] 2000) 1 year after ACL reconstruction. Study Design Cohort study (prognosis); Level of evidence, 2. Methods One hundred twenty patients who were treated with ACL reconstruction performed 4 single-legged hop tests preoperatively and 6 months after ACL reconstruction. Self-reported knee function within normal ranges was defined as IKDC 2000 scores greater than or equal to the age- and sex-specific normative 15th percentile score 1 year after surgery. Logistic regression analyses were performed to identify predictors of self-reported knee function within normal ranges. The area under the curve (AUC) from receiver operating characteristic curves was used as a measure of discriminative accuracy. Results Eighty-five patients completed single-legged hop tests 6 months after surgery and the 1-year follow-up with 68 patients classified as having self-reported knee function within normal ranges 1 year after reconstruction. The crossover hop and 6-m timed hop limb symmetry index (LSI) 6 months after ACL reconstruction were the strongest individual predictors of self-reported knee function (odds ratio, 1.09 and 1.10) and the only 2 tests in which the confidence intervals of the discriminatory accuracy (AUC) were above 0.5 (AUC = 0.68). Patients with knee function below normal ranges were over 5 times more likely of having a 6-m timed hop LSI lower than the 88% cutoff than those with knee function within normal ranges. Patients with knee function within normal ranges were 4 times more likely to have a crossover hop LSI greater than the 95% cutoff than those with knee function below normal ranges. No preoperative single-legged hop test predicted self-reported knee function within normal ranges 1 year after ACL reconstruction (all P > .353). Conclusion Single-legged hop tests conducted 6 months after ACL reconstruction can predict the likelihood of successful and unsuccessful outcome 1 year after ACL reconstruction. Patients demonstrating less than the 88% cutoff score on the 6-m timed hop test at 6 months may benefit from targeted training to improve limb symmetry in an attempt to normalize function. Patients with minimal side-to-side differences on the crossover hop test at 6 months possibly will have good knee function at 1 year if they continue with their current training regimen. Preoperative single-legged hop tests are not able to predict postoperative outcomes. PMID:22926749

Recognition of white matter bundles using local and global streamline-based registration and clustering.

PubMed

Garyfallidis, Eleftherios; Côté, Marc-Alexandre; Rheault, Francois; Sidhu, Jasmeen; Hau, Janice; Petit, Laurent; Fortin, David; Cunanne, Stephen; Descoteaux, Maxime

2018-04-15

Virtual dissection of diffusion MRI tractograms is cumbersome and needs extensive knowledge of white matter anatomy. This virtual dissection often requires several inclusion and exclusion regions-of-interest that make it a process that is very hard to reproduce across experts. Having automated tools that can extract white matter bundles for tract-based studies of large numbers of people is of great interest for neuroscience and neurosurgical planning. The purpose of our proposed method, named RecoBundles, is to segment white matter bundles and make virtual dissection easier to perform. This can help explore large tractograms from multiple persons directly in their native space. RecoBundles leverages latest state-of-the-art streamline-based registration and clustering to recognize and extract bundles using prior bundle models. RecoBundles uses bundle models as shape priors for detecting similar streamlines and bundles in tractograms. RecoBundles is 100% streamline-based, is efficient to work with millions of streamlines and, most importantly, is robust and adaptive to incomplete data and bundles with missing components. It is also robust to pathological brains with tumors and deformations. We evaluated our results using multiple bundles and showed that RecoBundles is in good agreement with the neuroanatomical experts and generally produced more dense bundles. Across all the different experiments reported in this paper, RecoBundles was able to identify the core parts of the bundles, independently from tractography type (deterministic or probabilistic) or size. Thus, RecoBundles can be a valuable method for exploring tractograms and facilitating tractometry studies. Copyright © 2017 Elsevier Inc. All rights reserved.

Amplitude reconstruction from complete photoproduction experiments and truncated partial-wave expansions

NASA Astrophysics Data System (ADS)

Workman, R. L.; Tiator, L.; Wunderlich, Y.; Döring, M.; Haberzettl, H.

2017-01-01

We compare the methods of amplitude reconstruction, for a complete experiment and a truncated partial-wave analysis, applied to the photoproduction of pseudoscalar mesons. The approach is pedagogical, showing in detail how the amplitude reconstruction (observables measured at a single energy and angle) is related to a truncated partial-wave analysis (observables measured at a single energy and a number of angles).

Amplitude reconstruction from complete photoproduction experiments and truncated partial-wave expansions

DOE PAGES

Workman, R. L.; Tiator, L.; Wunderlich, Y.; ...

2017-01-19

Here, we compare the methods of amplitude reconstruction, for a complete experiment and a truncated partial-wave analysis, applied to the photoproduction of pseudoscalar mesons. The approach is pedagogical, showing in detail how the amplitude reconstruction (observables measured at a single energy and angle) is related to a truncated partial-wave analysis (observables measured at a single energy and a number of angles).

Phase reconstruction using compressive two-step parallel phase-shifting digital holography

NASA Astrophysics Data System (ADS)

Ramachandran, Prakash; Alex, Zachariah C.; Nelleri, Anith

2018-04-01

The linear relationship between the sample complex object wave and its approximated complex Fresnel field obtained using single shot parallel phase-shifting digital holograms (PPSDH) is used in compressive sensing framework and an accurate phase reconstruction is demonstrated. It is shown that the accuracy of phase reconstruction of this method is better than that of compressive sensing adapted single exposure inline holography (SEOL) method. It is derived that the measurement model of PPSDH method retains both the real and imaginary parts of the Fresnel field but with an approximation noise and the measurement model of SEOL retains only the real part exactly equal to the real part of the complex Fresnel field and its imaginary part is completely not available. Numerical simulation is performed for CS adapted PPSDH and CS adapted SEOL and it is demonstrated that the phase reconstruction is accurate for CS adapted PPSDH and can be used for single shot digital holographic reconstruction.

On the concept of a filtered bundle

NASA Astrophysics Data System (ADS)

Bruce, Andrew James; Grabowska, Katarzyna; Grabowski, Janusz

We present the notion of a filtered bundle as a generalization of a graded bundle. In particular, we weaken the necessity of the transformation laws for local coordinates to exactly respect the weight of the coordinates by allowing more general polynomial transformation laws. The key examples of such bundles include affine bundles and various jet bundles, both of which play fundamental roles in geometric mechanics and classical field theory. We also present the notion of double filtered bundles which provide natural generalizations of double vector bundles and double affine bundles. Furthermore, we show that the linearization of a filtered bundle — which can be seen as a partial polarization of the admissible changes of local coordinates — is well defined.

Anatomy of the anterior cruciate ligament with regard to its two bundles.

PubMed

Petersen, Wolf; Zantop, Thore

2007-01-01

The anterior cruciate ligament (ACL) consists of two major fiber bundles, namely the anteromedial and posterolateral bundle. When the knee is extended, the posterolateral bundle (PL) is tight and the anteromedial (AM) bundle is moderately lax. As the knee is flexed, the femoral attachment of the ACL becomes a more horizontal orientation; causing the AM bundle to tighten and the PL bundle to relax. There is some degree of variability for the femoral origin of the anterome-dial and posterolateral bundle. The anteromedial bundle is located proximal and anterior in the femoral ACL origin (high and deep in the notch when the knee is flexed at 90 degrees ); the posterolateral bundle starts in the distal and posterior aspect of the femoral ACL origin (shallow and low when the knee is flexed at 90 degrees ). In the frontal plane the anteromedial bundle origin is in the 10:30 clock position and the postero-lateral bundle origin in the 9:30 clock position. At the tibial insertion the ACL fans out to form the foot region. The anteromedial bundle insertion is in the anterior part of the tibial ACL footprint, the posterolateral bundle in the posterior part. While the anteromedial bundle is the primary restraint against anterior tibial translation, the posterolateral bundle tends to stabilize the knee near full extension, particularly against rotatory loads.

Design of Multishell Sampling Schemes with Uniform Coverage in Diffusion MRI

PubMed Central

Caruyer, Emmanuel; Lenglet, Christophe; Sapiro, Guillermo; Deriche, Rachid

2017-01-01

Purpose In diffusion MRI, a technique known as diffusion spectrum imaging reconstructs the propagator with a discrete Fourier transform, from a Cartesian sampling of the diffusion signal. Alternatively, it is possible to directly reconstruct the orientation distribution function in q-ball imaging, providing so-called high angular resolution diffusion imaging. In between these two techniques, acquisitions on several spheres in q-space offer an interesting trade-off between the angular resolution and the radial information gathered in diffusion MRI. A careful design is central in the success of multishell acquisition and reconstruction techniques. Methods The design of acquisition in multishell is still an open and active field of research, however. In this work, we provide a general method to design multishell acquisition with uniform angular coverage. This method is based on a generalization of electrostatic repulsion to multishell. Results We evaluate the impact of our method using simulations, on the angular resolution in one and two bundles of fiber configurations. Compared to more commonly used radial sampling, we show that our method improves the angular resolution, as well as fiber crossing discrimination. Discussion We propose a novel method to design sampling schemes with optimal angular coverage and show the positive impact on angular resolution in diffusion MRI. PMID:23625329

Fast and Easy 3D Reconstruction with the Help of Geometric Constraints and Genetic Algorithms

NASA Astrophysics Data System (ADS)

Annich, Afafe; El Abderrahmani, Abdellatif; Satori, Khalid

2017-09-01

The purpose of the work presented in this paper is to describe new method of 3D reconstruction from one or more uncalibrated images. This method is based on two important concepts: geometric constraints and genetic algorithms (GAs). At first, we are going to discuss the combination between bundle adjustment and GAs that we have proposed in order to improve 3D reconstruction efficiency and success. We used GAs in order to improve fitness quality of initial values that are used in the optimization problem. It will increase surely convergence rate. Extracted geometric constraints are used first to obtain an estimated value of focal length that helps us in the initialization step. Matching homologous points and constraints is used to estimate the 3D model. In fact, our new method gives us a lot of advantages: reducing the estimated parameter number in optimization step, decreasing used image number, winning time and stabilizing good quality of 3D results. At the end, without any prior information about our 3D scene, we obtain an accurate calibration of the cameras, and a realistic 3D model that strictly respects the geometric constraints defined before in an easy way. Various data and examples will be used to highlight the efficiency and competitiveness of our present approach.

Reconstruction of closed rupture of thumb flexor tendon pulleys with a single free palmaris longus tendon graft: a case report and review of literature.

PubMed

Fazilleau, F; Cheval, D; Richou, J; Le Nen, D

2014-02-01

Closed rupture of thumb flexor tendon pulleys is extremely rare. Several techniques have already been described for finger pulley reconstruction. Various techniques based on prior anatomic and biomedical studies have been proposed for thumb pulley reconstruction, in which one or two of the three pulleys are replaced. In the present study, we describe an original technique using a single, free palmaris longus (PL) autograft for thumb pulley reconstruction. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Direct Synthesis of Lithium-Intercalated Graphene for Electrochemical Energy Storage Application

DTIC Science & Technology

2011-01-01

for Electrochemical Energy Storage Application Ashavani Kumar,† Arava Leela Mohana Reddy,†,* Arnab Mukherjee,‡ Madan Dubey,§ Xiaobo Zhan,† Neelam...L.; Loper, A. L.; Rao , A. M.; Eklund, P. C. Electrochemical Oxidation of Single Wall Carbon Nanotube Bundles in Sulfuric Acid. J. Phys. Chem. B 1999

Infrared imaging of cotton fiber bundles using a focal plane array detector and a single reflectance accessory

USDA-ARS?s Scientific Manuscript database

Infrared imaging is gaining attention as a technique used in the examination of cotton fibers. This type of imaging combines spectral analysis with spatial resolution to create visual images that examine sample composition and distribution. Herein, we report the use of an infrared instrument equippe...

Microwave and Millimeter Wave Properties of Vertically-Aligned Single Wall Carbon Nanotubes Films

NASA Astrophysics Data System (ADS)

Haddadi, K.; Tripon-Canseliet, C.; Hivin, Q.; Ducournau, G.; Teo, E.; Coquet, P.; Tay, B. K.; Lepilliet, S.; Avramovic, V.; Chazelas, J.; Decoster, D.

2016-05-01

We present the experimental determination of the complex permittivity of vertically aligned single wall carbon nanotubes (SWCNTs) films grown on quartz substrates in the microwave regime from 10 MHz up to 67 GHz, with the electrical field perpendicular to the main axis of the carbon nanotubes (CNTs), based on coplanar waveguide transmission line approach together with the measurement of the microwave impedance of top metalized vertically—aligned SWCNTs grown on conductive silicon substrates up to 26 GHz. From coplanar waveguide measurements, we obtain a real part of the permittivity almost equal to unity, which is interpreted in terms of low carbon atom density (3 × 1019 at/cm3) associated with a very low imaginary part of permittivity (<10-3) in the frequency range considered due to a very small perpendicular conductivity. The microwave impedance of a vertically aligned CNTs bundle equivalent to a low resistance reveals a good conductivity (3 S/cm) parallel to the CNTs axis. From these two kinds of data, we experimentally demonstrate the tensor nature of the vertically grown CNTs bundles.

Enhanced Raman Microprobe Imaging of Single-Wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Hadjiev, V. G.; Arepalli, S.; Nikolaev, P.; Jandl, S.; Yowell, L.

2003-01-01

We explore Raman microprobe capabilities to visualize single wall carbon nanotubes (SWCNTs). Although this technique is limited to a micron scale, we demonstrate that images of individual SWCNTs, bundles or their agglomerates can be generated by mapping Raman active elementary excitations. We measured the Raman response from carbon vibrations in SWCNTs excited by confocal scanning of a focused laser beam. Carbon vibrations reveal key characteristics of SWCNTs as nanotube diameter distribution (radial breathing modes, RBM, 100-300 cm(exp -1)), presence of defects and functional groups (D-mode, 1300-1350 cm(exp -1)), strain and oxidation states of SWCNTs, as well as metallic or semiconducting character of the tubes encoded in the lineshape of the G-modes at 1520-1600 cm(exp - 1). In addition, SWCNTs are highly anisotropic scatterers. The Raman response from a SWCNT is maximal for incident light polarization parallel to the tube axis and vanishing for perpendicular directions. We show that the SWCNT bundle shape or direction can be determined, with some limitations, from a set of Raman images taken at two orthogonal directions of the incident light polarization.

Altered white matter tract property related to impaired focused attention, sustained attention, cognitive impulsivity and vigilance in attention-deficit/hyperactivity disorder

PubMed Central

Chiang, Huey-Ling; Chen, Yu-Jen; Lo, Yu-Chun; Tseng, Wen-Yih Isaac; Gau, Susan Shur-Fen

2015-01-01

Background The neural substrate for clinical symptoms and neuropsychological performance in individuals with attention-deficit/hyperactivity disorder (ADHD) has rarely been studied and has yielded inconsistent results. We sought to compare the microstructural property of fibre tracts associated with the prefrontal cortex and its association with ADHD symptoms and a wide range of attention performance in youth with ADHD and healthy controls. Methods We assessed youths with ADHD and age-, sex-, handedness-, coil- and intelligence-matched controls using the Conners’ Continuous Performance Test (CCPT) for attention performance and MRI. The 10 target tracts, including the bilateral frontostriatal tracts (caudate to dorsolateral prefrontal cortex, ventrolateral prefrontal cortex and orbitofrontal cortex), superior longitudinal fasciculus (SLF) and cingulum bundle were reconstructed using diffusion spectrum imaging tractography. We computed generalized fractional anisotropy (GFA) values to indicate tract-specific microstructural property. Results We included 50 youths with ADHD and 50 healthy controls in our study. Youths with ADHD had lower GFA in the left frontostriatal tracts, bilateral SLF and right cingulum bundle and performed worse in the CCPT than controls. Furthermore, alteration of the right SLF GFA was most significantly associated with the clinical symptom of inattention in youths with ADHD. Finally, youths with ADHD had differential association patterns of the 10 fibre tract GFA values with attention performance compared with controls. Limitations Ten of the youths with ADHD were treated with methylphenidate, which may have long-term effects on microstructural property. Conclusion Our study highlights the importance of the SLF, cingulum bundle and frontostriatal tracts for clinical symptoms and attention performance in youths with ADHD and demonstrates the involvement of different fibre tracts in attention performance in these individuals. PMID:25871496

Altered white matter tract property related to impaired focused attention, sustained attention, cognitive impulsivity and vigilance in attention-deficit/ hyperactivity disorder.

PubMed

Chiang, Huey-Ling; Chen, Yu-Jen; Lo, Yu-Chun; Tseng, Wen-Yih I; Gau, Susan S

2015-09-01

The neural substrate for clinical symptoms and neuropsychological performance in individuals with attention-deficit/hyperactivity disorder (ADHD) has rarely been studied and has yielded inconsistent results. We sought to compare the microstructural property of fibre tracts associated with the prefrontal cortex and its association with ADHD symptoms and a wide range of attention performance in youth with ADHD and healthy controls. We assessed youths with ADHD and age-, sex-, handedness-, coil- and intelligence-matched controls using the Conners' Continuous Performance Test (CCPT) for attention performance and MRI. The 10 target tracts, including the bilateral frontostriatal tracts (caudate to dorsolateral prefrontal cortex, ventrolateral prefrontal cortex and orbitofrontal cortex), superior longitudinal fasciculus (SLF) and cingulum bundle were reconstructed using diffusion spectrum imaging tractography. We computed generalized fractional anisotropy (GFA) values to indicate tract-specific microstructural property. We included 50 youths with ADHD and 50 healthy controls in our study. Youths with ADHD had lower GFA in the left frontostriatal tracts, bilateral SLF and right cingulum bundle and performed worse in the CCPT than controls. Furthermore, alteration of the right SLF GFA was most significantly associated with the clinical symptom of inattention in youths with ADHD. Finally, youths with ADHD had differential association patterns of the 10 fibre tract GFA values with attention performance compared with controls. Ten of the youths with ADHD were treated with methylphenidate, which may have long-term effects on microstructural property. Our study highlights the importance of the SLF, cingulum bundle and frontostriatal tracts for clinical symptoms and attention performance in youths with ADHD and demonstrates the involvement of different fibre tracts in attention performance in these individuals.

The iMars web-GIS - spatio-temporal data queries and single image web map services

NASA Astrophysics Data System (ADS)

Walter, S. H. G.; Steikert, R.; Schreiner, B.; Sidiropoulos, P.; Tao, Y.; Muller, J.-P.; Putry, A. R. D.; van Gasselt, S.

2017-09-01

We introduce a new approach for a system dedicated to planetary surface change detection by simultaneous visualisation of single-image time series in a multi-temporal context. In the context of the EU FP-7 iMars project we process and ingest vast amounts of automatically co-registered (ACRO) images. The base of the co-registration are the high precision HRSC multi-orbit quadrangle image mosaics, which are based on bundle-block-adjusted multi-orbit HRSC DTMs.

Electrophysiological characteristics of the Marshall bundle in humans

PubMed Central

Han, Seongwook; Joung, Boyoung; Scanavacca, Mauricio; Sosa, Eduardo; Chen, Peng-Sheng; Hwang, Chun

2010-01-01

BACKGROUND Marshall bundles (MBs) are the muscle bundles within the ligament of Marshall. OBJECTIVE This trial sought to the electrophysiological characteristics of the MB and the anatomical connections between MB and left atrium (LA) in patients with persistent atrial fibrillation (AF). METHODS We enrolled 72 patients (male:female 59:13, age 59.9 ± 9.4 years) who underwent MB mapping and ablation for AF. MB mapping was done via an endocardial or epicardial approach during sinus rhythm and AF. RESULTS Recordings were successful in 64 of 72 patients (89%). A single connection was noted in 11 of 64 patients between the MB and the coronary sinus (CS) muscle sleeves. The MB recordings showed distinct MB potentials with a proximal-to-distal activation pattern during sinus rhythm. During AF, organized passive activations and dissociated slow MB ectopic activities were commonly observed in this type of connection. Double connections to both CS and LA around left pulmonary veins were noted in 23 of 64 patients (36%). After the ablation of the distal connection, MB recording showed typical double potentials as in single connection. Multiple connections were noted in 30 of 64 patients (47%). During sinus rhythm, the earliest activation was in the middle of the MB. The activation patterns were irregular and variable in each patient. During AF, rapid and fractionated complex activations were noted in all patients of this group. CONCLUSION We documented 3 different types of MB–LA connections. Rapid and fractionated activations were most commonly observed in the MB that had multiple LA connections. PMID:20188860

The Physiology of Mechanoelectrical Transduction Channels in Hearing

PubMed Central

Fettiplace, Robert; Kim, Kyunghee X.

2014-01-01

Much is known about the mechanotransducer (MT) channels mediating transduction in hair cells of the vertrbrate inner ear. With the use of isolated preparations, it is experimentally feasible to deliver precise mechanical stimuli to individual cells and record the ensuing transducer currents. This approach has shown that small (1–100 nm) deflections of the hair-cell stereociliary bundle are transmitted via interciliary tip links to open MT channels at the tops of the stereocilia. These channels are cation-permeable with a high selectivity for Ca2+; two channels are thought to be localized at the lower end of the tip link, each with a large single-channel conductance that increases from the low- to high-frequency end of the cochlea. Ca2+ influx through open channels regulates their resting open probability, which may contribute to setting the hair cell resting potential in vivo. Ca2+ also controls transducer fast adaptation and force generation by the hair bundle, the two coupled processes increasing in speed from cochlear apex to base. The molecular intricacy of the stereocilary bundle and the transduction apparatus is reflected by the large number of single-gene mutations that are linked to sensorineural deafness, especially those in Usher syndrome. Studies of such mutants have led to the discovery of many of the molecules of the transduction complex, including the tip link and its attachments to the stereociliary core. However, the MT channel protein is still not firmly identified, nor is it known whether the channel is activated by force delivered through accessory proteins or by deformation of the lipid bilayer. PMID:24987009

Gas phase synthesis of non-bundled, small diameter single-walled carbon nanotubes with near-armchair chiralities

NASA Astrophysics Data System (ADS)

Mustonen, K.; Laiho, P.; Kaskela, A.; Zhu, Z.; Reynaud, O.; Houbenov, N.; Tian, Y.; Susi, T.; Jiang, H.; Nasibulin, A. G.; Kauppinen, E. I.

2015-07-01

We present a floating catalyst synthesis route for individual, i.e., non-bundled, small diameter single-walled carbon nanotubes (SWCNTs) with a narrow chiral angle distribution peaking at high chiralities near the armchair species. An ex situ spark discharge generator was used to form iron particles with geometric number mean diameters of 3-4 nm and fed into a laminar flow chemical vapour deposition reactor for the continuous synthesis of long and high-quality SWCNTs from ambient pressure carbon monoxide. The intensity ratio of G/D peaks in Raman spectra up to 48 and mean tube lengths up to 4 μm were observed. The chiral distributions, as directly determined by electron diffraction in the transmission electron microscope, clustered around the (n,m) indices (7,6), (8,6), (8,7), and (9,6), with up to 70% of tubes having chiral angles over 20°. The mean diameter of SWCNTs was reduced from 1.10 to 1.04 nm by decreasing the growth temperature from 880 to 750 °C, which simultaneously increased the fraction of semiconducting tubes from 67% to 80%. Limiting the nanotube gas phase number concentration to ˜105 cm-3 prevented nanotube bundle formation that is due to collisions induced by Brownian diffusion. Up to 80% of 500 as-deposited tubes observed by atomic force and transmission electron microscopy were individual. Transparent conducting films deposited from these SWCNTs exhibited record low sheet resistances of 63 Ω/□ at 90% transparency for 550 nm light.

Morphology of the bryozoan Cinctipora elegans (Cyclostomata, Cinctiporidae) with first data on its sexual reproduction and the cyclostome neuro-muscular system.

PubMed

Schwaha, Thomas F; Handschuh, Stephan; Ostrovsky, Andrew N; Wanninger, Andreas

2018-06-14

Cyclostome bryozoans are an ancient group of marine colonial suspension-feeders comprising approximately 700 extant species. Previous morphological studies are mainly restricted to skeletal characters whereas data on soft tissues obtained by state-of-the-art methods are still lacking. In order to contribute to issues related to cyclostome ground pattern reconstruction, we analyzed the morphology of the neuromuscular system Cinctipora elegans by means of immunocytochemical staining, confocal laser scanning microscopy, histological sections and microCT imaging. Polypides of C. elegans are located in elongated tubular skeletal cystids. Distally, the orifice leads into a prominent vestibulum which is lined by an epithelium that joins an almost complete perimetrical attachment organ, both containing radially arranged neurite bundles and muscles. Centrally, the prominent atrial sphincter separates the vestibulum from the atrium. The latter is enclosed by the tentacle sheath which contains few longitudinal muscle fibers and two principal neurite bundles. These emerge from the cerebral ganglion, which is located at the lophophoral base. Lateral ganglia are located next to the cerebral ganglion from which the visceral neurite bundles emerge that extend proximally towards the foregut. There are four tentacle neurite bundles that emerge from the ganglia and the circum-oral nerve ring, which encompasses the pharynx. The tentacles possess two striated longitudinal muscles. Short buccal dilatators are situated at the lophophoral base and short muscular sets are present at the abfrontal and frontal side of the tentacle base. The pharynx is myoepithelial and triradiate in cross-section. Oocytes are found inside the pharyngeal myoepithelium. The digestive tract contains dense circular musculature and few longitudinal muscles. The membranous sac contains regular, thin, circular and diagonal muscles and neurites in its epithelial lining. The general structure of the neuro-muscular system is more reminiscent of the condition found in Gymnolaemata rather than Phylactolaemata, which supports a close relationship between Cyclostomata and Gymnolaemata. Several characters of C. elegans such as the lateral ganglia or loss of the cardia are probably apomorphic for this species. For the first time, oocytes that surprisingly develop in the pharyngeal wall are reported for this species.

Bundled monocapillary optics

DOEpatents

Hirsch, Gregory

2002-01-01

A plurality of glass or metal wires are precisely etched to form the desired shape of the individual channels of the final polycapillary optic. This shape is created by carefully controlling the withdrawal speed of a group of wires from an etchant bath. The etched wires undergo a subsequent operation to create an extremely smooth surface. This surface is coated with a layer of material which is selected to maximize the reflectivity of the radiation being used. This reflective surface may be a single layer of material, or a multilayer coating for optimizing the reflectivity in a narrower wavelength interval. The collection of individual wires is assembled into a close-packed multi-wire bundle, and the wires are bonded together in a manner which preserves the close-pack configuration, irrespective of the local wire diameter. The initial wires are then removed by either a chemical etching procedure or mechanical force. In the case of chemical etching, the bundle is generally segmented by cutting a series of etching slots. Prior to removing the wire, the capillary array is typically bonded to a support substrate. The result of the process is a bundle of precisely oriented radiation-reflecting hollow channels. The capillary optic is used for efficiently collecting and redirecting the radiation from a source of radiation which could be the anode of an x-ray tube, a plasma source, the fluorescent radiation from an electron microprobe, a synchrotron radiation source, a reactor or spallation source of neutrons, or some other source.

Study on bubbly flow behavior in natural circulation reactor by thermal-hydraulic simulation tests with SF6-Gas and ethanol liquid

NASA Astrophysics Data System (ADS)

Kondo, Yoshiyuki; Suga, Keishi; Hibi, Koki; Okazaki, Toshihiko; Komeno, Toshihiro; Kunugi, Tomoaki; Serizawa, Akimi; Yoneda, Kimitoshi; Arai, Takahiro

2009-02-01

An advanced experimental technique has been developed to simulate two-phase flow behavior in a light water reactor (LWR). The technique applies three kinds of methods; (1) use of sulfur-hexafluoride (SF6) gas and ethanol (C2H5OH) liquid at atmospheric temperature and a pressure less than 1.0MPa, where the fluid properties are similar to steam-water ones in the LWR, (2) generation of bubble with a sintering tube, which simulates bubble generation on heated surface in the LWR, (3) measurement of detailed bubble distribution data with a bi-optical probe (BOP), (4) and measurement of liquid velocities with the tracer liquid. This experimental technique provides easy visualization of flows by using a large scale experimental apparatus, which gives three-dimensional flows, and measurement of detailed spatial distributions of two-phase flow. With this technique, we have carried out experiments simulating two-phase flow behavior in a single-channel geometry, a multi-rod-bundle one, and a horizontal-tube-bundle one on a typical natural circulation reactor system. Those experiments have clarified a) a flow regime map in a rod bundle on the transient region between bubbly and churn flow, b) three-dimensional flow behaviour in rod-bundles where inter-subassembly cross-flow occurs, c) bubble-separation behavior with consideration of reactor internal structures. The data have given analysis models for the natural circulation reactor design with good extrapolation.

Assessment of SFR Wire Wrap Simulation Uncertainties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Delchini, Marc-Olivier G.; Popov, Emilian L.; Pointer, William David

Predictive modeling and simulation of nuclear reactor performance and fuel are challenging due to the large number of coupled physical phenomena that must be addressed. Models that will be used for design or operational decisions must be analyzed for uncertainty to ascertain impacts to safety or performance. Rigorous, structured uncertainty analyses are performed by characterizing the model’s input uncertainties and then propagating the uncertainties through the model to estimate output uncertainty. This project is part of the ongoing effort to assess modeling uncertainty in Nek5000 simulations of flow configurations relevant to the advanced reactor applications of the Nuclear Energy Advancedmore » Modeling and Simulation (NEAMS) program. Three geometries are under investigation in these preliminary assessments: a 3-D pipe, a 3-D 7-pin bundle, and a single pin from the Thermal-Hydraulic Out-of-Reactor Safety (THORS) facility. Initial efforts have focused on gaining an understanding of Nek5000 modeling options and integrating Nek5000 with Dakota. These tasks are being accomplished by demonstrating the use of Dakota to assess parametric uncertainties in a simple pipe flow problem. This problem is used to optimize performance of the uncertainty quantification strategy and to estimate computational requirements for assessments of complex geometries. A sensitivity analysis to three turbulent models was conducted for a turbulent flow in a single wire wrapped pin (THOR) geometry. Section 2 briefly describes the software tools used in this study and provides appropriate references. Section 3 presents the coupling interface between Dakota and a computational fluid dynamic (CFD) code (Nek5000 or STARCCM+), with details on the workflow, the scripts used for setting up the run, and the scripts used for post-processing the output files. In Section 4, the meshing methods used to generate the THORS and 7-pin bundle meshes are explained. Sections 5, 6 and 7 present numerical results for the 3-D pipe, the single pin THORS mesh, and the 7-pin bundle mesh, respectively.« less

The phylogenetic significance of the carpophore in Apiaceae

PubMed Central

Liu, Mei; Plunkett, Gregory M.; Van Wyk, Ben-Erik; Tilney, Patricia M.; Lowry, Porter P.

2012-01-01

Background and aims Fruit structural characters have traditionally been important in the taxonomy of the family Apiaceae. Previous investigations using a limited number of taxa have shown that the carpophore may be especially useful in helping to circumscribe subfamily Azorelloideae. The present study examines, for the first time, carpophore structure in 92 species from 43 genera, representing all subfamilies of Apiaceae, and including all genera assigned to subfamily Azorelloideae. Phylogenetic interpretations are made for the first time, using all available information, and a standard terminology is proposed to describe the various character states found in carpophores. Methods Carpophore structure was studied in detail using light microscopy. Key Results Carpophores, when present, may be categorized into two main groups (B and C) based mainly on the arrangement of the vascular bundles in transverse section, and further divided into six sub-types according to the length of the carpophore (short in B1 and C1) and whether they are entire (B1–B3 and C1) or bifurcate (B4 and C2). Free carpophores are absent in subfamily Mackinlayoideae, and in tribes Lichtensteinieae and Phlyctidocarpeae, which have two opposite vascular bundles (Group A). Entire carpophores with one or two vascular bundles, or bifurcate carpophores with lateral vascular bundles (arranged side by side within the commissural plane), are the main types characterizing Azorelloideae. The short, hygroscopic carpophores found in Choritaenia are unique in Apiaceae and provide additional evidence for the exclusion of this genus from Azorelloideae. Carpophore type C2 is typical for most Apioideae sensu lato (exceptions are, for example, Arctopus and Alepidea, which have type B2). Conclusions A single carpophore and ventral vascular bundles not forming free carpophores are proposed to be the ancestral conditions in Apiaceae, while bifurcate carpophores with opposite vascular bundles are the derived state, present in most Apioideae. Secondary reductions seem to have occurred in several unrelated lineages in all major groups, e.g. many Azorelloideae, several protoapioids (including nearly all members of the tribe Saniculeae) and 29 euapioid genera (e.g. some Oenantheae). PMID:22966116

Nanomechanics modeling of carbon nanotubes interacting with surfaces in various configurations

NASA Astrophysics Data System (ADS)

Wu, Yu-Chiao

Carbon nanotubes (CNTs) have been widely used as potential components in reported nanoelectromechanical (NEM) devices due to their excellent mechanical and electrical properties. This thesis models the experiments by the continuum mechanics in two distinct scenarios. In the first situation, measurements are made of CNT configurations after manipulations. Modeling is then used to determine the interfacial properties during the manipulation which led to the observed configuration. This technique is used to determine the shear stress between a SWNT bundle and other materials. During manipulation, a SWNT bundle slipped on two micro-cantilevers. According to the slack due to the slippage after testing and the device configuration, the shear stress between a SWNT bundle and other materials can be determined. In another model, the work of adhesion was determined on two accidentally fabricated devices. Through the configuration of two SWNT adhered bundles and the force-distance curves measured by an atomic force microscope (AFM), modeling was used to determine the work of adhesion between two bundles and the shear stress at the SWNT-substrate interface. In the second situation, modeling is used in a more traditional fashion to make theoretical predictions as to how a device will operate. Using this technique, the actuation mechanism of a single-trench SWNT-based switch was investigated. During the actuation, the deflection-induced tension causes the SWNT bundle to slip on both platforms and to be partially peeled from two side recessed electrodes. These effects produce a slack which reduces the threshold voltages subsequent to the first actuation. The result shows excellent agreement between the theory and the measurement. Furthermore, the operation of a double-trenched SWNT-based switch was investigated. A slack is produced in the 1st actuated trench region by the slip and peeling effects. This slack reduces the 2nd actuation voltage in the neighbor trench. Finally, the adhesive slip process at the SWNT-substrate interface was simulated. The result shows that the force for slip of a SWNT remains constant for lengths less than about 240 nm. Beyond that length, increasing the contact length causes increase the force for slippage. This phenomenon agrees well with reported experiments.

ANATOMICAL RECONSTRUCTION OF ANTERIOR CRUCIATE LIGAMENT OF THE KNEE: DOUBLE BAND OR SINGLE BAND?

PubMed

Zanella, Luiz Antonio Zanotelli; Junior, Adair Bervig; Badotti, Augusto Alves; Michelin, Alexandre Froes; Algarve, Rodrigo Ilha; de Quadros Martins, Cesar Antonio

2012-01-01

To evaluate the double-band and single-band techniques for anatomical reconstruction of the anterior cruciate ligament of the knee and demonstrate that the double-band technique not only provides greater anterior stability but also causes less pain and a better subjective patient response. We selected 42 patients who underwent anterior cruciate ligament reconstruction, by means of either the single-band anatomical reconstruction technique, using flexor tendon grafts with two tunnels, or the double-band anatomical reconstruction technique, using four tunnels and grafts from the semitendinosus and gracilis tendons. All fixations were performed using interference screws. There was no variation in the sample. Before the operation, the objective and subjective IKDC scores, Lysholm score and length of time with the injury were evaluated. All these variables were reassessed six months later, and the KT-1000 correlation with the contralateral knee was also evaluated. There was no significant difference between the two groups in subjective evaluations, but the single-band group showed better results in relation to range of motion and objective evaluations including KT-1000 (with statistical significance). Our study demonstrated that there was no difference between the two groups in subjective evaluations, but better results were found using the single-band anatomical technique, in relation to objective evaluations.

ANATOMICAL RECONSTRUCTION OF ANTERIOR CRUCIATE LIGAMENT OF THE KNEE: DOUBLE BAND OR SINGLE BAND?

PubMed Central

Zanella, Luiz Antonio Zanotelli; Junior, Adair Bervig; Badotti, Augusto Alves; Michelin, Alexandre Froes; Algarve, Rodrigo Ilha; de Quadros Martins, Cesar Antonio

2015-01-01

Objective: To evaluate the double-band and single-band techniques for anatomical reconstruction of the anterior cruciate ligament of the knee and demonstrate that the double-band technique not only provides greater anterior stability but also causes less pain and a better subjective patient response. Methods: We selected 42 patients who underwent anterior cruciate ligament reconstruction, by means of either the single-band anatomical reconstruction technique, using flexor tendon grafts with two tunnels, or the double-band anatomical reconstruction technique, using four tunnels and grafts from the semitendinosus and gracilis tendons. All fixations were performed using interference screws. There was no variation in the sample. Before the operation, the objective and subjective IKDC scores, Lysholm score and length of time with the injury were evaluated. All these variables were reassessed six months later, and the KT-1000 correlation with the contralateral knee was also evaluated. Results: There was no significant difference between the two groups in subjective evaluations, but the single-band group showed better results in relation to range of motion and objective evaluations including KT-1000 (with statistical significance). Conclusion: Our study demonstrated that there was no difference between the two groups in subjective evaluations, but better results were found using the single-band anatomical technique, in relation to objective evaluations. PMID:27042621

Intraluminal laser speckle rheology using an omni-directional viewing catheter

PubMed Central

Wang, Jing; Hosoda, Masaki; Tshikudi, Diane M.; Hajjarian, Zeinab; Nadkarni, Seemantini K.

2016-01-01

A number of disease conditions in luminal organs are associated with alterations in tissue mechanical properties. Here, we report a new omni-directional viewing Laser Speckle Rheology (LSR) catheter for mapping the mechanical properties of luminal organs without the need for rotational motion. The LSR catheter incorporates multiple illumination fibers, an optical fiber bundle and a multi-faceted mirror to permit omni-directional viewing of the luminal wall. By retracting the catheter using a motor-drive assembly, cylindrical maps of tissue mechanical properties are reconstructed. Evaluation conducted in a test phantom with circumferentially-varying mechanical properties demonstrates the capability of the LSR catheter for the accurate mechanical assessment of luminal organs. PMID:28101407

The pedicled masseter muscle transfer for smile reconstruction in facial paralysis: repositioning the origin and insertion.

PubMed

Matic, Damir B; Yoo, John

2012-08-01

The pedicled masseter muscle transfer (PMMT) is introduced as a new reconstructive option for dynamic smile restoration in patients with facial paralysis. The masseter muscle is detached from both its origin and insertion and transferred to a new position to imitate the function of the native zygomaticus major muscle. Part one of this study consisted of cadaveric dissections of 4 heads (eight sides) in order to determine whether the masseter muscle could be (a) pedicled solely by its dominant neurovascular bundle and (b) repositioned directly over the native zygomaticus major. The second part of the study consisted of clinical assessments in three patients in order to confirm the applicability of this muscle transfer. Commissure excursion and vector of contraction following PMMT were compared to the non-paralyzed side. In all eight sides, the masseter muscles were successfully isolated on their pedicle and transposed on top of and in-line with the ipsilateral zygomaticus major. The mean length of the masseter and its angle from Frankfurt's horizontal line after transposition compared favorably to the native zygomaticus major muscle. In the clinical cases, the mean commissure movements of the paralyzed and normal sides were 7 mm and 12 mm respectively. The mean angles of commissural movement for the paralyzed and normal sides were 62° and 59° respectively. The PMMT can be used as a dynamic reconstruction for patients with permanent facial paralysis. As we gain experience with the PMMT, it may be possible to use it as a first-line option for patients not eligible for free micro-neurovascular reconstruction. Copyright © 2012 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Study on the Spatial Resolution of Single and Multiple Coincidences Compton Camera

NASA Astrophysics Data System (ADS)

Andreyev, Andriy; Sitek, Arkadiusz; Celler, Anna

2012-10-01

In this paper we study the image resolution that can be obtained from the Multiple Coincidences Compton Camera (MCCC). The principle of MCCC is based on a simultaneous acquisition of several gamma-rays emitted in cascade from a single nucleus. Contrary to a standard Compton camera, MCCC can theoretically provide the exact location of a radioactive source (based only on the identification of the intersection point of three cones created by a single decay), without complicated tomographic reconstruction. However, practical implementation of the MCCC approach encounters several problems, such as low detection sensitivities result in very low probability of coincident triple gamma-ray detection, which is necessary for the source localization. It is also important to evaluate how the detection uncertainties (finite energy and spatial resolution) influence identification of the intersection of three cones, thus the resulting image quality. In this study we investigate how the spatial resolution of the reconstructed images using the triple-cone reconstruction (TCR) approach compares to images reconstructed from the same data using standard iterative method based on single-cone. Results show, that FWHM for the point source reconstructed with TCR was 20-30% higher than the one obtained from the standard iterative reconstruction based on expectation maximization (EM) algorithm and conventional single-cone Compton imaging. Finite energy and spatial resolutions of the MCCC detectors lead to errors in conical surfaces definitions (“thick” conical surfaces) which only amplify in image reconstruction when intersection of three cones is being sought. Our investigations show that, in spite of being conceptually appealing, the identification of triple cone intersection constitutes yet another restriction of the multiple coincidence approach which limits the image resolution that can be obtained with MCCC and TCR algorithm.

Development of serotonin-like immunoreactivity in the embryos and larvae of nudibranch mollusks with emphasis on the structure and possible function of the apical sensory organ.

PubMed

Kempf, S C; Page, L R; Pires, A

1997-09-29

This investigation provides a light and electron microscopic examination of the development of serotonin-like immunoreactivity and structure of the apical sensory organ (ASO) in embryos and/or larvae of four nudibranch species: Berghia verrucicornis, Phestilla sibogae, Melibe leonina, and Tritonia diomedea. Serotonin-like immunoreactivity is first expressed in somata, dendrites, and axons of a group of five distinct neurons within the ASO. These neurons extend axons into an apical neuropil, a structure that is situated centrally and immediately dorsal to the cerebral commissure. Three of these neurons possess sensory dendrites that extend through the pretrochal epithelium, each supporting two cilia at their distal ends. Later development of serotonin-like immunoreactivity includes 1) axons from the apical neuropil that extend into each of the velar lobes; 2) neuron perikarya in the cerebral and pedal ganglia; 3) axons that extend through the cerebral commissure, cerebral-pedal connectives, pedal commissure, and possibly the visceral loop connective; and 4) axons extending from each pedal ganglion into the larval foot. Ultrastructurally, the ASO can be seen to be composed of three lobes and an apical neuropil that is separately delineated from the cerebral commissure. Four cell types are present within the ASO: ciliary tuft cells, type I and type II parampullary neurons, and ampullary neurons. Immunofluorescence and 3,3' diaminobenzidine tetrahydrochloride (DAB) labeling verify that the serotonergic neurons of the ASO are type I and type II parampullary neurons. The ampullary and type I parampullary neurons possess dendrites that extend through the pretrochal epithelium. These dendrites are partitioned into three bundles, one on either side of the ciliary tuft cells and a third bundle penetrating the pretrochal epithelium centrally between the ciliary tuft cells. One serotonergic type I parampullary neuron is associated with each of these bundles. Two ampullary neurons are associated with each of the lateral dendritic bundles, while the central bundle includes only one. Ultrastructural analyses of serotonergic axonal innervation arising from the ASO agree with those determined from fluorescently labeled material. The structure of the ASO and its associated serotonergic axons suggest that the serotonergic component of this structure senses environmental stimuli affecting velar function, possibly the contractility of muscle fibers in the velar lobes. Similarities and differences among the ASOs of embryos and larvae from various invertebrate phyla may provide useful data that will assist in the reconstruction of phylogenetic relationships.

Single-shot speckle reduction in numerical reconstruction of digitally recorded holograms.

PubMed

Hincapie, Diego; Herrera-Ramírez, Jorge; Garcia-Sucerquia, Jorge

2015-04-15

A single-shot method to reduce the speckle noise in the numerical reconstructions of electronically recorded holograms is presented. A recorded hologram with the dimensions N×M is split into S=T×T sub-holograms. The uncorrelated superposition of the individually reconstructed sub-holograms leads to an image with the speckle noise reduced proportionally to the 1/S law. The experimental results are presented to support the proposed methodology.

Fluid mechanics of swimming bacteria with multiple flagella.

PubMed

Kanehl, Philipp; Ishikawa, Takuji

2014-04-01

It is known that some kinds of bacteria swim by forming a bundle of their multiple flagella. However, the details of flagella synchronization as well as the swimming efficiency of such bacteria have not been fully understood. In this study, swimming of multiflagellated bacteria is investigated numerically by the boundary element method. We assume that the cell body is a rigid ellipsoid and the flagella are rigid helices suspended on flexible hooks. Motors apply constant torque to the hooks, rotating the flagella either clockwise or counterclockwise. Rotating all flagella clockwise, bundling of all flagella is observed in every simulated case. It is demonstrated that the counter rotation of the body speeds up the bundling process. During this procedure the flagella synchronize due to hydrodynamic interactions. Moreover, the results illustrated that during running the multiflagellated bacterium shows higher propulsive efficiency (distance traveled per one flagellar rotation) over a bacterium with a single thick helix. With an increasing number of flagella the propulsive efficiency increases, whereas the energetic efficiency decreases, which indicates that efficiency is something multiflagellated bacteria are assigning less priority to than to motility. These findings form a fundamental basis in understanding bacterial physiology and metabolism.

Effects of number and configuration of flagella on motility of Helicobacter species.

NASA Astrophysics Data System (ADS)

Constantino, Maira A.; Sharba, Sinan; Shen, Zeli; Fox, James G.; Haesebrouck, Freddy; Linden, Sara; Bansil, Rama

Helicobacters are ulcer-causing bacteria that colonize the viscoelastic gastric mucus layer of mammals. Previous studies have shown that motility and colonization are affected by helical body shape, number and configuration of flagella. In a recent study, using fast time-resolution and high-magnification 2-D phase-contrast microscopy to image individual helical and rod-shaped H. pylori we measured the rotation rate of the cell body and flagella and found that helical shape produces less than 15% changes in swimming speeds as compared to the rod-shaped cell. Motility of H. pylori was strongly influenced by its multiple unipolar flagella. Here we compare rotational and translational speeds of H. cetorum and H. suis which have bipolar flagella, with H. cetorum having single bipolar flagella and H. suis having multiple flagella. Preliminary results show that H. suis bacteria swim slower but rotate at the same rate as H. pylori and present two swimming modes. It can swim as a pusher, with one active rotating bundle and one inactive bundle, wrapped around the body or with both bundles active. Similar work on H. cetorum is ongoing and will also be presented. NSF PHY 1410798.

SPIDER image processing for single-particle reconstruction of biological macromolecules from electron micrographs

PubMed Central

Shaikh, Tanvir R; Gao, Haixiao; Baxter, William T; Asturias, Francisco J; Boisset, Nicolas; Leith, Ardean; Frank, Joachim

2009-01-01

This protocol describes the reconstruction of biological molecules from the electron micrographs of single particles. Computation here is performed using the image-processing software SPIDER and can be managed using a graphical user interface, termed the SPIDER Reconstruction Engine. Two approaches are described to obtain an initial reconstruction: random-conical tilt and common lines. Once an existing model is available, reference-based alignment can be used, a procedure that can be iterated. Also described is supervised classification, a method to look for homogeneous subsets when multiple known conformations of the molecule may coexist. PMID:19180078

Verification of the FBR fuel bundle-duct interaction analysis code BAMBOO by the out-of-pile bundle compression test with large diameter pins

NASA Astrophysics Data System (ADS)

Uwaba, Tomoyuki; Ito, Masahiro; Nemoto, Junichi; Ichikawa, Shoichi; Katsuyama, Kozo

2014-09-01

The BAMBOO computer code was verified by results for the out-of-pile bundle compression test with large diameter pin bundle deformation under the bundle-duct interaction (BDI) condition. The pin diameters of the examined test bundles were 8.5 mm and 10.4 mm, which are targeted as preliminary fuel pin diameters for the upgraded core of the prototype fast breeder reactor (FBR) and for demonstration and commercial FBRs studied in the FaCT project. In the bundle compression test, bundle cross-sectional views were obtained from X-ray computer tomography (CT) images and local parameters of bundle deformation such as pin-to-duct and pin-to-pin clearances were measured by CT image analyses. In the verification, calculation results of bundle deformation obtained by the BAMBOO code analyses were compared with the experimental results from the CT image analyses. The comparison showed that the BAMBOO code reasonably predicts deformation of large diameter pin bundles under the BDI condition by assuming that pin bowing and cladding oval distortion are the major deformation mechanisms, the same as in the case of small diameter pin bundles. In addition, the BAMBOO analysis results confirmed that cladding oval distortion effectively suppresses BDI in large diameter pin bundles as well as in small diameter pin bundles.

Single-stage interpolation flaps in facial reconstruction.

PubMed

Hollmig, S Tyler; Leach, Brian C; Cook, Joel

2014-09-01

Relatively deep and complex surgical defects, particularly when adjacent to or involving free margins, present significant reconstructive challenges. When the use of local flaps is precluded by native anatomic restrictions, interpolation flaps may be modified to address these difficult wounds in a single operative session. To provide a framework to approach difficult soft tissue defects arising near or involving free margins and to demonstrate appropriate design and execution of single-stage interpolation flaps for reconstruction of these wounds. Examination of our utilization of these flaps based on an anatomic region and surgical approach. A region-based demonstration of flap conceptualization, design, and execution is provided. Tunneled, transposed, and deepithelialized variations of single-stage interpolation flaps provide versatile options for reconstruction of a variety of defects encroaching on or involving free margins. The inherently robust vascularity of these flaps supports importation of necessary tissue bulk while allowing aggressive contouring to restore an intricate native topography. Critical flap design allows access to distant tissue reservoirs and placement of favorable incision lines while preserving the inherent advantages of a single operative procedure.

Landing mechanics during single hop for distance in females following anterior cruciate ligament reconstruction compared to healthy controls.

PubMed

Trigsted, Stephanie M; Post, Eric G; Bell, David R

2017-05-01

To determine possible differences in single-hop kinematics and kinetics in females with anterior cruciate ligament reconstruction compared to healthy controls. A second purpose was to make comparisons between the healthy and reconstructed limbs. Subjects were grouped based on surgical status (33 ACLR patients and 31 healthy controls). 3D motion capture synchronized with force plates was used to capture the landing phase of three successful trials of single hop for distance during a single data collection session. Peak values during the loading phase were analysed. Subjects additionally completed three successful trials of the triple hop for distance Tegner activity scale and International Knee Document Committee 2000 (IKDC). Controls demonstrated greater peak knee flexion and greater internal knee extension moment and hip extension moment than ACLR subjects. Within the ACLR group, the healthy limb exhibited greater peak knee flexion, hip flexion, hip extension moment, single hop and triple hops for distance and normalized quadriceps strength. Patients who undergo anterior cruciate ligament reconstruction land in a more extended posture when compared to healthy controls and compared to their healthy limb. III.

Dissection of molecular assembly dynamics by tracking orientation and position of single molecules in live cells

PubMed Central

McQuilken, Molly; La Riviere, Patrick J.; Occhipinti, Patricia; Verma, Amitabh; Oldenbourg, Rudolf; Gladfelter, Amy S.; Tani, Tomomi

2016-01-01

Regulation of order, such as orientation and conformation, drives the function of most molecular assemblies in living cells but remains difficult to measure accurately through space and time. We built an instantaneous fluorescence polarization microscope, which simultaneously images position and orientation of fluorophores in living cells with single-molecule sensitivity and a time resolution of 100 ms. We developed image acquisition and analysis methods to track single particles that interact with higher-order assemblies of molecules. We tracked the fluctuations in position and orientation of molecules from the level of an ensemble of fluorophores down to single fluorophores. We tested our system in vitro using fluorescently labeled DNA and F-actin, in which the ensemble orientation of polarized fluorescence is known. We then tracked the orientation of sparsely labeled F-actin network at the leading edge of migrating human keratinocytes, revealing the anisotropic distribution of actin filaments relative to the local retrograde flow of the F-actin network. Additionally, we analyzed the position and orientation of septin-GFP molecules incorporated in septin bundles in growing hyphae of a filamentous fungus. Our data indicate that septin-GFP molecules undergo positional fluctuations within ∼350 nm of the binding site and angular fluctuations within ∼30° of the central orientation of the bundle. By reporting position and orientation of molecules while they form dynamic higher-order structures, our approach can provide insights into how micrometer-scale ordered assemblies emerge from nanoscale molecules in living cells. PMID:27679846

Double-layer versus single-layer bone-patellar tendon-bone anterior cruciate ligament reconstruction: a prospective randomized study with 3-year follow-up.

PubMed

Mei, Xiaoliang; Zhang, Zhenxiang; Yang, Jingwen

2016-12-01

To evaluate the clinical results of a randomized controlled trial of single-layer versus double-layer bone-patellar tendon-bone (BPTB) anterior cruciate ligament (ACL) reconstruction. Fifty-eight subjects who underwent primary ACL reconstruction with a BPTB allograft were prospectively randomized into two groups: single-layer reconstruction (n = 31) and double-layer reconstruction (n = 27). The following evaluation methods were used: clinical examination, KT-1000 arthrometer measurement, muscle strength, Tegner activity score, Lysholm score, subjective rating scale regarding patient satisfaction and sports performance level, graft retear, contralateral ACL tear, and additional meniscus surgery. Forty-eight subjects (24 in single-layer group and 24 in double-layer group) who were followed up for 3 years were evaluated. Preoperatively, there were no differences between the groups. At 3-year follow-up, the Lachman and pivot-shift test results were better in the double-layer group (P = 0.019 and P < 0.0001, respectively). KT measurements were better in the double-layer group (mean 2.9 versus 1.5 mm; P = 0.0025). The Tegner score was also better in the double-layer group (P = 0.024). There were no significant differences in range of motion, muscle strength, Lysholm score, subjective rating scale, graft retear, and secondary meniscal tear. In ACL reconstruction, double-layer BPTB reconstruction was significantly better than single-layer reconstruction regarding anterior and rotational stability at 3-year follow-up. The results of KT measurements and the Lachman and pivot-shift tests were significantly better in the double-layer group, whereas there was no difference in the anterior drawer test results. The Tegner score was also better in the double-layer group; however, there were no differences in the other subjective findings.

Calculation of single chain cellulose elasticity using fully atomistic modeling

Treesearch

Xiawa Wu; Robert J. Moon; Ashlie Martini

2011-01-01

Cellulose nanocrystals, a potential base material for green nanocomposites, are ordered bundles of cellulose chains. The properties of these chains have been studied for many years using atomic-scale modeling. However, model predictions are difficult to interpret because of the significant dependence of predicted properties on model details. The goal of this study is...

An In Vitro Robotic Assessment of the Anterolateral Ligament, Part 2: Anterolateral Ligament Reconstruction Combined With Anterior Cruciate Ligament Reconstruction.

PubMed

Nitri, Marco; Rasmussen, Matthew T; Williams, Brady T; Moulton, Samuel G; Cruz, Raphael Serra; Dornan, Grant J; Goldsmith, Mary T; LaPrade, Robert F

2016-03-01

Recent biomechanical studies have demonstrated that an extra-articular lateral knee structure, most recently referred to as the anterolateral ligament (ALL), contributes to overall rotational stability of the knee. However, the effect of anatomic ALL reconstruction (ALLR) in the setting of anterior cruciate ligament (ACL) reconstruction (ACLR) has not been biomechanically investigated or validated. The purpose of this study was to investigate the biomechanical function of anatomic ALLR in the setting of a combined ACL and ALL injury. More specifically, this investigation focused on the effect of ALLR on resultant rotatory stability when performed in combination with concomitant ACLR. It was hypothesized that ALLR would significantly reduce internal rotation and axial plane translation laxity during a simulated pivot-shift test compared with isolated ACLR. Controlled laboratory study. Ten fresh-frozen cadaveric knees were evaluated with a 6 degrees of freedom robotic system. Knee kinematics were evaluated with simulated clinical examinations including a simulated pivot-shift test consisting of coupled 10-N·m valgus and 5-N·m internal rotation torques, a 5-N·m internal rotation torque, and an 88-N anterior tibial load. Kinematic differences between ACLR with an intact ALL, ACLR with ALLR, and ACLR with a deficient ALL were compared with the intact state. Single-bundle ACLR tunnels and ALLR tunnels were placed anatomically according to previous quantitative anatomic attachment descriptions. Combined anatomic ALLR and ACLR significantly improved the rotatory stability of the knee compared with isolated ACLR in the face of a concurrent ALL deficiency. During a simulated pivot-shift test, ALLR significantly reduced internal rotation and axial plane tibial translation when compared with ACLR with an ALL deficiency. Isolated ACLR for the treatment of a combined ACL and ALL injury was not able to restore stability of the knee, resulting in a significant increase in residual internal rotation laxity. ALLR did not affect anterior tibial translation; no significant differences were observed between the varying ALL conditions with ACLR except between ACLR with an intact ALL and ACLR with a deficient ALL at 0° of flexion. In the face of a combined ACL and ALL deficiency, concurrent ACLR and ALLR significantly improved the rotatory stability of the knee compared with solely reconstructing the ACL. Significant increases in residual internal rotation and laxity during the pivot-shift test may exist in both acute and chronic settings of an ACL deficiency and in patients treated with isolated ACLR for a combined ACL and ALL deficiency. For this subset of patients, surgical treatment of the ALL, in addition to ACLR, should be considered to restore knee stability. © 2016 The Author(s).

Corneal stroma microfibrils.

PubMed

Hanlon, Samuel D; Behzad, Ali R; Sakai, Lynn Y; Burns, Alan R

2015-03-01

Elastic tissue was first described well over a hundred years ago and has since been identified in nearly every part of the body. In this review, we examine elastic tissue in the corneal stroma with some mention of other ocular structures which have been more thoroughly described in the past. True elastic fibers consist of an elastin core surrounded by fibrillin microfibrils. However, the presence of elastin fibers is not a requirement and some elastic tissue is comprised of non-elastin-containing bundles of microfibrils. Fibers containing a higher relative amount of elastin are associated with greater elasticity and those without elastin, with structural support. Recently it has been shown that the microfibrils, not only serve mechanical roles, but are also involved in cell signaling through force transduction and the release of TGF-β. A well characterized example of elastin-free microfibril bundles (EFMBs) is found in the ciliary zonules which suspend the crystalline lens in the eye. Through contraction of the ciliary muscle they exert enough force to reshape the lens and thereby change its focal point. It is believed that the molecules comprising these fibers do not turn-over and yet retain their tensile strength for the life of the animal. The mechanical properties of the cornea (strength, elasticity, resiliency) would suggest that EFMBs are present there as well. However, many authors have reported that, although present during embryonic and early postnatal development, EFMBs are generally not present in adults. Serial-block-face imaging with a scanning electron microscope enabled 3D reconstruction of elements in murine corneas. Among these elements were found fibers that formed an extensive network throughout the cornea. In single sections these fibers appeared as electron dense patches. Transmission electron microscopy provided additional detail of these patches and showed them to be composed of fibrils (∼10 nm diameter). Immunogold evidence clearly identified these fibrils as fibrillin EFMBs and EFMBs were also observed with TEM (without immunogold) in adult mammals of several species. Evidence of the presence of EFMBs in adult corneas will hopefully pique an interest in further studies that will ultimately improve our understanding of the cornea's biomechanical properties and its capacity to repair. Copyright © 2015 Elsevier Ltd. All rights reserved.

Corneal Stroma Microfibrils

PubMed Central

Hanlon, Samuel D.; Behzad, Ali R.; Sakai, Lynn Y.; Burns, Alan R.

2015-01-01

Elastic tissue was first described well over a hundred years ago and has since been identified in nearly every part of the body. In this review, we examine elastic tissue in the corneal stroma with some mention of other ocular structures which have been more thoroughly described in the past. True elastic fibers consist of an elastin core surrounded by fibrillin microfibrils. However, the presence of elastin fibers is not a requirement and some elastic tissue is comprised of non-elastin-containing bundles of microfibrils. Fibers containing a higher relative amount of elastin are associated with greater elasticity and those without elastin, with structural support. Recently it has been shown that the microfibrils, not only serve mechanical roles, but are also involved in cell signaling through force transduction and the release of TGF-β. A well characterized example of elastin-free microfibril bundles (EFMBs) is found in the ciliary zonules which suspend the crystalline lens in the eye. Through contraction of the ciliary muscle they exert enough force to reshape the lens and thereby change its focal point. It is believed that the molecules comprising these fibers do not turn-over and yet retain their tensile strength for the life of the animal. The mechanical properties of the cornea (strength, elasticity, resiliency) would suggest that EFMBs are present there as well. However, many authors have reported that, although present during embryonic and early postnatal development, EFMBs are generally not present in adults. Serial-block-face imaging with a scanning electron microscope enabled 3D reconstruction of elements in murine corneas. Among these elements were found fibers that formed an extensive network throughout the cornea. In single sections these fibers appeared as electron dense patches. Transmission electron microscopy provided additional detail of these patches and showed them to be composed of fibrils (∼10nm diameter). Immunogold evidence clearly identified these fibrils as fibrillin EFMBs and EFMBs were also observed with TEM (without immunogold) in adult mammals of several species. Evidence of the presence of EFMBs in adult corneas will hopefully pique an interest in further studies that will ultimately improve our understanding of the cornea's biomechanical properties and its capacity to repair. PMID:25613072

The Evolutionary Basis of Naturally Diverse Rice Leaves Anatomy

PubMed Central

Chatterjee, Jolly; Dionora, Jacqueline; Elmido-Mabilangan, Abigail; Wanchana, Samart; Thakur, Vivek; Bandyopadhyay, Anindya; Brar, Darshan S.; Quick, William Paul

2016-01-01

Rice contains genetically and ecologically diverse wild and cultivated species that show a wide variation in plant and leaf architecture. A systematic characterization of leaf anatomy is essential in understanding the dynamics behind such diversity. Therefore, leaf anatomies of 24 Oryza species spanning 11 genetically diverse rice genomes were studied in both lateral and longitudinal directions and possible evolutionary trends were examined. A significant inter-species variation in mesophyll cells, bundle sheath cells, and vein structure was observed, suggesting precise genetic control over these major rice leaf anatomical traits. Cellular dimensions, measured along three growth axes, were further combined proportionately to construct three-dimensional (3D) leaf anatomy models to compare the relative size and orientation of the major cell types present in a fully expanded leaf. A reconstruction of the ancestral leaf state revealed that the following are the major characteristics of recently evolved rice species: fewer veins, larger and laterally elongated mesophyll cells, with an increase in total mesophyll area and in bundle sheath cell number. A huge diversity in leaf anatomy within wild and domesticated rice species has been portrayed in this study, on an evolutionary context, predicting a two-pronged evolutionary pathway leading to the ‘sativa leaf type’ that we see today in domesticated species. PMID:27792743

The Evolutionary Basis of Naturally Diverse Rice Leaves Anatomy.

PubMed

Chatterjee, Jolly; Dionora, Jacqueline; Elmido-Mabilangan, Abigail; Wanchana, Samart; Thakur, Vivek; Bandyopadhyay, Anindya; Brar, Darshan S; Quick, William Paul

2016-01-01

Rice contains genetically and ecologically diverse wild and cultivated species that show a wide variation in plant and leaf architecture. A systematic characterization of leaf anatomy is essential in understanding the dynamics behind such diversity. Therefore, leaf anatomies of 24 Oryza species spanning 11 genetically diverse rice genomes were studied in both lateral and longitudinal directions and possible evolutionary trends were examined. A significant inter-species variation in mesophyll cells, bundle sheath cells, and vein structure was observed, suggesting precise genetic control over these major rice leaf anatomical traits. Cellular dimensions, measured along three growth axes, were further combined proportionately to construct three-dimensional (3D) leaf anatomy models to compare the relative size and orientation of the major cell types present in a fully expanded leaf. A reconstruction of the ancestral leaf state revealed that the following are the major characteristics of recently evolved rice species: fewer veins, larger and laterally elongated mesophyll cells, with an increase in total mesophyll area and in bundle sheath cell number. A huge diversity in leaf anatomy within wild and domesticated rice species has been portrayed in this study, on an evolutionary context, predicting a two-pronged evolutionary pathway leading to the 'sativa leaf type' that we see today in domesticated species.

Signal detection by active, noisy hair bundles

NASA Astrophysics Data System (ADS)

O'Maoiléidigh, Dáibhid; Salvi, Joshua D.; Hudspeth, A. J.

2018-05-01

Vertebrate ears employ hair bundles to transduce mechanical movements into electrical signals, but their performance is limited by noise. Hair bundles are substantially more sensitive to periodic stimulation when they are mechanically active, however, than when they are passive. We developed a model of active hair-bundle mechanics that predicts the conditions under which a bundle is most sensitive to periodic stimulation. The model relies only on the existence of mechanotransduction channels and an active adaptation mechanism that recloses the channels. For a frequency-detuned stimulus, a noisy hair bundle's phase-locked response and degree of entrainment as well as its detection bandwidth are maximized when the bundle exhibits low-amplitude spontaneous oscillations. The phase-locked response and entrainment of a bundle are predicted to peak as functions of the noise level. We confirmed several of these predictions experimentally by periodically forcing hair bundles held near the onset of self-oscillation. A hair bundle's active process amplifies the stimulus preferentially over the noise, allowing the bundle to detect periodic forces less than 1 pN in amplitude. Moreover, the addition of noise can improve a bundle's ability to detect the stimulus. Although, mechanical activity has not yet been observed in mammalian hair bundles, a related model predicts that active but quiescent bundles can oscillate spontaneously when they are loaded by a sufficiently massive object such as the tectorial membrane. Overall, this work indicates that auditory systems rely on active elements, composed of hair cells and their mechanical environment, that operate on the brink of self-oscillation.

Tissue Expansion Using Hyaluronic Acid Filler for Single-Stage Ear Reconstruction: A Novel Concept for Difficult Areas.

PubMed

Inbal, Amir; Lemelman, Benjamin T; Millet, Eran; Greensmith, Andrew

2017-10-16

Auricular reconstruction is one of the most challenging procedures in plastic surgery. An adequate skin envelope is essential for cartilage framework coverage, yet few good options exist without additional surgery. We propose a novel method for minimally invasive tissue expansion, using hyaluronic acid (HA) filler to allow for single-stage ear reconstruction. To introduce the novel concept of HA filler for tissue expansion in ear reconstruction, and as an alternative to traditional expansion techniques. Macrolane is a large particle HA gel developed for large volume restoration. Expansion of the non-hair-bearing mastoid skin was performed in our clinic weekly or every other week. Final expansion was completed one week prior to reconstructive surgery. Tissue from one patient's expanded pocket was sent for histological analysis. Ten patients underwent single-stage auricular reconstruction with preoperative expansion. Injection sessions ranged from 7 to 13 (mean, 9.7). Mean injected volume per session was 2.03 mL per patient, for an average total of 19.8 mL (range, 14.5-30 mL). There were no major complications. One minor complication required removal of exposed wire from the antihelix in the office. Hematoxylin and eosin stain revealed similar histology to that seen with traditional expanders. This novel expansion technique using serial HA injections allowed for optimized skin coverage in single-stage ear reconstruction. The concept of tissue expansion using HA filler is a new frontier for research that may be applicable to other arenas of reconstruction. 4. © 2017 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com

Computer-assisted resection and reconstruction of bilateral osteoradionecrosis of the mandible using 2 separate flaps prepared from a single fibula.

PubMed

Chen, Rui; Zhang, Han-Qing; Huang, Zi-Xian; Li, Shi-Hao; Zhang, Da-Ming; Huang, Zhi-Quan

2018-03-07

Osteoradionecrosis of the mandible is a late radiation-induced complication, which is a major concern in survivors of head and neck cancer. In this study, we present a case of a patient with nasopharyngeal carcinoma who developed extensive bilateral osteoradionecrosis of the ascending ramus of the mandible. After preoperative virtual surgical planning, the obtained data were used to fabricate patient-specific cutting templates. The bilateral mandibular defects were reconstructed using 2 separate flaps prepared from a single fibula. Both defects were successfully reconstructed, and satisfactory aesthetic and functional results were achieved. Bilateral mandibular osteoradionecrosis can be managed with virtual surgical planning, and the defects can be reconstructed using 2 separate flaps prepared from a single fibula. Copyright © 2018 Elsevier Inc. All rights reserved.

Capturing molecular multimode relaxation processes in excitable gases based on decomposition of acoustic relaxation spectra

NASA Astrophysics Data System (ADS)

Zhu, Ming; Liu, Tingting; Wang, Shu; Zhang, Kesheng

2017-08-01

Existing two-frequency reconstructive methods can only capture primary (single) molecular relaxation processes in excitable gases. In this paper, we present a reconstructive method based on the novel decomposition of frequency-dependent acoustic relaxation spectra to capture the entire molecular multimode relaxation process. This decomposition of acoustic relaxation spectra is developed from the frequency-dependent effective specific heat, indicating that a multi-relaxation process is the sum of the interior single-relaxation processes. Based on this decomposition, we can reconstruct the entire multi-relaxation process by capturing the relaxation times and relaxation strengths of N interior single-relaxation processes, using the measurements of acoustic absorption and sound speed at 2N frequencies. Experimental data for the gas mixtures CO2-N2 and CO2-O2 validate our decomposition and reconstruction approach.

Crossed Module Bundle Gerbes; Classification, String Group and Differential Geometry

NASA Astrophysics Data System (ADS)

Jurčo, Branislav

We discuss nonabelian bundle gerbes and their differential geometry using simplicial methods. Associated to any crossed module there is a simplicial group NC, the nerve of the 1-category defined by the crossed module and its geometric realization |NC|. Equivalence classes of principal bundles with structure group |NC| are shown to be one-to-one with stable equivalence classes of what we call crossed module gerbes bundle gerbes. We can also associate to a crossed module a 2-category C'. Then there are two equivalent ways how to view classifying spaces of NC-bundles and hence of |NC|-bundles and crossed module bundle gerbes. We can either apply the W-construction to NC or take the nerve of the 2-category C'. We discuss the string group and string structures from this point of view. Also a simplicial principal bundle can be equipped with a simplicial connection and a B-field. It is shown how in the case of a simplicial principal NC-bundle these simplicial objects give the bundle gerbe connection and the bundle gerbe B-field.

Cognitive Severity-Specific Neuronal Degenerative Network in Charcoal Burning Suicide-Related Carbon Monoxide Intoxication

PubMed Central

Chen, Nai-Ching; Huang, Chi-Wei; Huang, Shu-Hua; Chang, Wen-Neng; Chang, Ya-Ting; Lui, Chun-Chung; Lin, Pin-Hsuan; Lee, Chen-Chang; Chang, Yen-Hsiang; Chang, Chiung-Chih

2015-01-01

Abstract While carbon monoxide (CO) intoxication often triggers multiple intraneuronal immune- or inflammatory-related cascades, it is not known whether the pathological processes within the affected regions evolve equally in the long term. To understand the neurodegenerative networks, we examined 49 patients with a clinical diagnosis of CO intoxication related to charcoal burning suicide at the chronic stage and compared them with 15 age- and sex-matched controls. Reconstructions of degenerative networks were performed using T1 magnetic resonance imaging, diffusion-tensor imaging, and fluorodeoxyglucose positron emission tomography (PET). Tract-specific fractional anisotropy (FA) quantification of 11 association fibers was performed while the clinical significance of the reconstructed structural or functional networks was determined by correlating them with the cognitive parameters. Compared with the controls, the patients had frontotemporal gray matter (GM) atrophy, diffuse white matter (WM) FA decrement, and axial diffusivity (AD) increment. The patients were further stratified into 3 groups based on the cognitive severities. The spatial extents within the frontal-insular-caudate GM as well as the prefrontal WM AD increment regions determined the cognitive severities among 3 groups. Meanwhile, the prefrontal WM FA values and PET signals also correlated significantly with the patient's Mini-Mental State Examination score. Frontal hypometabolic patterns in PET analysis, even after adjusted for GM volume, were highly coherent to the GM atrophic regions, suggesting structural basis of functional alterations. Among the calculated major association bundles, only the anterior thalamic radiation FA values correlated significantly with all chosen cognitive scores. Our findings suggest that fronto-insular-caudate areas represent target degenerative network in CO intoxication. The topography that occurred at a cognitive severity-specific level at the chronic phase suggested the clinical roles of frontal areas. Although changes in FA are also diffusely distributed, different regional changes in AD suggested unequal long-term compensatory capacities among WM bundles. As such, the affected WM regions showing irreversible changes may exert adverse impacts to the interconnected GM structures. PMID:25984663

Anatomical approach to permanent His bundle pacing: Optimizing His bundle capture.

PubMed

Vijayaraman, Pugazhendhi; Dandamudi, Gopi

2016-01-01

Permanent His bundle pacing is a physiological alternative to right ventricular pacing. In this article we describe our approach to His bundle pacing in patients with AV nodal and intra-Hisian conduction disease. It is essential for the implanters to understand the anatomic variations of the His bundle course and its effect on the type of His bundle pacing achieved. We describe several case examples to illustrate our anatomical approach to permanent His bundle pacing in this article. Copyright © 2016 Elsevier Inc. All rights reserved.

Contributions of the N- and C-terminal helical segments to the lipid-free structure and lipid interaction of apolipoprotein A-I.

PubMed

Tanaka, Masafumi; Dhanasekaran, Padmaja; Nguyen, David; Ohta, Shinya; Lund-Katz, Sissel; Phillips, Michael C; Saito, Hiroyuki

2006-08-29

The tertiary structure of lipid-free apolipoprotein (apo) A-I in the monomeric state comprises two domains: a N-terminal alpha-helix bundle and a less organized C-terminal domain. This study examined how the N- and C-terminal segments of apoA-I (residues 1-43 and 223-243), which contain the most hydrophobic regions in the molecule and are located in opposite structural domains, contribute to the lipid-free conformation and lipid interaction. Measurements of circular dichroism in conjunction with tryptophan and 8-anilino-1-naphthalenesulfonic acid fluorescence data demonstrated that single (L230P) or triple (L230P/L233P/Y236P) proline insertions into the C-terminal alpha helix disrupted the organization of the C-terminal domain without affecting the stability of the N-terminal helix bundle. In contrast, proline insertion into the N terminus (Y18P) disrupted the bundle structure in the N-terminal domain, indicating that the alpha-helical segment in this region is part of the helix bundle. Calorimetric and gel-filtration measurements showed that disruption of the C-terminal alpha helix significantly reduced the enthalpy and free energy of binding of apoA-I to lipids, whereas disruption of the N-terminal alpha helix had only a small effect on lipid binding. Significantly, the presence of the Y18P mutation offset the negative effects of disruption/removal of the C-terminal helical domain on lipid binding, suggesting that the alpha helix around Y18 concealed a potential lipid-binding region in the N-terminal domain, which was exposed by the disruption of the helix-bundle structure. When these results are taken together, they indicate that the alpha-helical segment in the N terminus of apoA-I modulates the lipid-free structure and lipid interaction in concert with the C-terminal domain.

Patient Perception of Value in Bundled Payments for Total Joint Arthroplasty.

PubMed

Schwartz, Adam J; Fraser, James F; Shannon, Allison M; Jackson, Nikki T; Raghu, T S

2016-12-01

A central concern for providers in a bundled payment model is determining how the bundle is distributed. Prior studies have shown that current reimbursement rates are often not aligned with patients' values. While willingness-to-pay (WTP) surveys are perhaps useful in a fee-for-service arrangement to determine overall reimbursement, the percentage of payment distribution might be as or more important in a bundled payment model. All patients undergoing primary total joint arthroplasty by a single surgeon were offered participation in a preoperative WTP survey. At a minimum 3 months postoperatively, patients were mailed instructions for an online follow-up survey asking how they would allocate a hypothetical bonus payment. From January through December 2014, 45 patients agreed to participate in the preoperative WTP survey. Twenty patients who were minimum 3 months postoperative also completed the follow-up survey. Patients valued total knee and hip arthroplasty at $28,438 (95% confidence interval [CI]: $20,551-36,324) and $39,479 (95% CI: $27,848-$51,112), respectively. At 3 months postoperatively, patients distributed a hypothetical bonus payment 55.5% to the surgeon (95% CI: 47.8%-63.1%), 38% to the hospital (95% CI: 30.3%-45.7%), and 6.5% (95% CI: -1.2% to 14.2%) to the implant manufacturer (P < .001). The data suggest that total joint arthroplasty patients have vastly different perceptions of payment distributions than what actually exists. In contrast to the findings of this study, the true distribution of payments for an episode of care averages 65% to the hospital, 27% to the implant manufacturer, and 8% to the surgeon. While many drivers of payment distribution exist, this study suggests that patients would allocate a larger proportion of a bundled payment to surgeons than is currently disbursed. This finding may also provide a plausible explanation for patients' consistent overestimation of surgeon reimbursements. Copyright © 2016 Elsevier Inc. All rights reserved.

Mechanism of Interaction Between the General Anesthetic Halothane and a Model Ion Channel Protein, I: Structural Investigations via X-Ray Reflectivity from Langmuir Monolayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strzalka, J.; Liu, J; Tronin, A

2009-01-01

We previously reported the synthesis and structural characterization of a model membrane protein comprised of an amphiphilic 4-helix bundle peptide with a hydrophobic domain based on a synthetic ion channel and a hydrophilic domain with designed cavities for binding the general anesthetic halothane. In this work, we synthesized an improved version of this halothane-binding amphiphilic peptide with only a single cavity and an otherwise identical control peptide with no such cavity, and applied x-ray reflectivity to monolayers of these peptides to probe the distribution of halothane along the length of the core of the 4-helix bundle as a function ofmore » the concentration of halothane. At the moderate concentrations achieved in this study, approximately three molecules of halothane were found to be localized within a broad symmetric unimodal distribution centered about the designed cavity. At the lowest concentration achieved, of approximately one molecule per bundle, the halothane distribution became narrower and more peaked due to a component of {approx}19Angstroms width centered about the designed cavity. At higher concentrations, approximately six to seven molecules were found to be uniformly distributed along the length of the bundle, corresponding to approximately one molecule per heptad. Monolayers of the control peptide showed only the latter behavior, namely a uniform distribution along the length of the bundle irrespective of the halothane concentration over this range. The results provide insight into the nature of such weak binding when the dissociation constant is in the mM regime, relevant for clinical applications of anesthesia. They also demonstrate the suitability of both the model system and the experimental technique for additional work on the mechanism of general anesthesia, some of it presented in the companion parts II and III under this title.« less

Analytic image reconstruction from partial data for a single-scan cone-beam CT with scatter correction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Min, Jonghwan; Pua, Rizza; Cho, Seungryong, E-mail: scho@kaist.ac.kr

Purpose: A beam-blocker composed of multiple strips is a useful gadget for scatter correction and/or for dose reduction in cone-beam CT (CBCT). However, the use of such a beam-blocker would yield cone-beam data that can be challenging for accurate image reconstruction from a single scan in the filtered-backprojection framework. The focus of the work was to develop an analytic image reconstruction method for CBCT that can be directly applied to partially blocked cone-beam data in conjunction with the scatter correction. Methods: The authors developed a rebinned backprojection-filteration (BPF) algorithm for reconstructing images from the partially blocked cone-beam data in amore » circular scan. The authors also proposed a beam-blocking geometry considering data redundancy such that an efficient scatter estimate can be acquired and sufficient data for BPF image reconstruction can be secured at the same time from a single scan without using any blocker motion. Additionally, scatter correction method and noise reduction scheme have been developed. The authors have performed both simulation and experimental studies to validate the rebinned BPF algorithm for image reconstruction from partially blocked cone-beam data. Quantitative evaluations of the reconstructed image quality were performed in the experimental studies. Results: The simulation study revealed that the developed reconstruction algorithm successfully reconstructs the images from the partial cone-beam data. In the experimental study, the proposed method effectively corrected for the scatter in each projection and reconstructed scatter-corrected images from a single scan. Reduction of cupping artifacts and an enhancement of the image contrast have been demonstrated. The image contrast has increased by a factor of about 2, and the image accuracy in terms of root-mean-square-error with respect to the fan-beam CT image has increased by more than 30%. Conclusions: The authors have successfully demonstrated that the proposed scanning method and image reconstruction algorithm can effectively estimate the scatter in cone-beam projections and produce tomographic images of nearly scatter-free quality. The authors believe that the proposed method would provide a fast and efficient CBCT scanning option to various applications particularly including head-and-neck scan.« less

Warps, grids and curvature in triple vector bundles

NASA Astrophysics Data System (ADS)

Flari, Magdalini K.; Mackenzie, Kirill

2018-06-01

A triple vector bundle is a cube of vector bundle structures which commute in the (strict) categorical sense. A grid in a triple vector bundle is a collection of sections of each bundle structure with certain linearity properties. A grid provides two routes around each face of the triple vector bundle, and six routes from the base manifold to the total manifold; the warps measure the lack of commutativity of these routes. In this paper we first prove that the sum of the warps in a triple vector bundle is zero. The proof we give is intrinsic and, we believe, clearer than the proof using decompositions given earlier by one of us. We apply this result to the triple tangent bundle T^3M of a manifold and deduce (as earlier) the Jacobi identity. We further apply the result to the triple vector bundle T^2A for a vector bundle A using a connection in A to define a grid in T^2A . In this case the curvature emerges from the warp theorem.

Measurement of the TeV atmospheric muon charge ratio with the complete OPERA data set

NASA Astrophysics Data System (ADS)

Agafonova, N.; Aleksandrov, A.; Anokhina, A.; Aoki, S.; Ariga, A.; Ariga, T.; Bender, D.; Bertolin, A.; Bozza, C.; Brugnera, R.; Buonaura, A.; Buontempo, S.; Büttner, B.; Chernyavsky, M.; Chukanov, A.; Consiglio, L.; D'Ambrosio, N.; De Lellis, G.; De Serio, M.; Del Amo Sanchez, P.; Di Crescenzo, A.; Di Ferdinando, D.; Di Marco, N.; Dmitrievski, S.; Dracos, M.; Duchesneau, D.; Dusini, S.; Dzhatdoev, T.; Ebert, J.; Ereditato, A.; Fini, R. A.; Fukuda, T.; Galati, G.; Garfagnini, A.; Giacomelli, G.; Göllnitz, C.; Goldberg, J.; Gornushkin, Y.; Grella, G.; Guler, M.; Gustavino, C.; Hagner, C.; Hara, T.; Hollnagel, A.; Hosseini, B.; Ishida, H.; Ishiguro, K.; Jakovcic, K.; Jollet, C.; Kamiscioglu, C.; Kamiscioglu, M.; Kawada, J.; Kim, J. H.; Kim, S. H.; Kitagawa, N.; Klicek, B.; Kodama, K.; Komatsu, M.; Kose, U.; Kreslo, I.; Lauria, A.; Lenkeit, J.; Ljubicic, A.; Longhin, A.; Loverre, P.; Malgin, A.; Malenica, M.; Mandrioli, G.; Matsuo, T.; Matveev, V.; Mauri, N.; Medinaceli, E.; Meregaglia, A.; Mikado, S.; Monacelli, P.; Montesi, M. C.; Morishima, K.; Muciaccia, M. T.; Naganawa, N.; Naka, T.; Nakamura, M.; Nakano, T.; Nakatsuka, Y.; Niwa, K.; Ogawa, S.; Okateva, N.; Olshevsky, A.; Omura, T.; Ozaki, K.; Paoloni, A.; Park, B. D.; Park, I. G.; Pasqualini, L.; Pastore, A.; Patrizii, L.; Pessard, H.; Pistillo, C.; Podgrudkov, D.; Polukhina, N.; Pozzato, M.; Pupilli, F.; Roda, M.; Rokujo, H.; Roganova, T.; Rosa, G.; Ryazhskaya, O.; Sato, O.; Schembri, A.; Shakiryanova, I.; Shchedrina, T.; Sheshukov, A.; Shibuya, H.; Shiraishi, T.; Shoziyoev, G.; Simone, S.; Sioli, M.; Sirignano, C.; Sirri, G.; Spinetti, M.; Stanco, L.; Starkov, N.; Stellacci, S. M.; Stipcevic, M.; Strolin, P.; Takahashi, S.; Tenti, M.; Terranova, F.; Tioukov, V.; Tufanli, S.; Vilain, P.; Vladimirov, M.; Votano, L.; Vuilleumier, J. L.; Wilquet, G.; Wonsak, B.; Yoon, C. S.; Zemskova, S.; Zghiche, A.

2014-07-01

The OPERA detector, designed to search for oscillations in the CNGS beam, is located in the underground Gran Sasso laboratory, a privileged location to study TeV-scale cosmic rays. For the analysis here presented, the detector was used to measure the atmospheric muon charge ratio in the TeV region. OPERA collected charge-separated cosmic ray data between 2008 and 2012. More than 3 million atmospheric muon events were detected and reconstructed, among which about 110000 multiple muon bundles. The charge ratio was measured separately for single and for multiple muon events. The analysis exploited the inversion of the magnet polarity which was performed on purpose during the 2012 Run. The combination of the two data sets with opposite magnet polarities allowed minimizing systematic uncertainties and reaching an accurate determination of the muon charge ratio. Data were fitted to obtain relevant parameters on the composition of primary cosmic rays and the associated kaon production in the forward fragmentation region. In the surface energy range 1-20 TeV investigated by OPERA, is well described by a parametric model including only pion and kaon contributions to the muon flux, showing no significant contribution of the prompt component. The energy independence supports the validity of Feynman scaling in the fragmentation region up to TeV/nucleon primary energy.

Architecture of vasa recta in the renal inner medulla of the desert rodent Dipodomys merriami: potential impact on the urine concentrating mechanism.

PubMed

Issaian, Tadeh; Urity, Vinoo B; Dantzler, William H; Pannabecker, Thomas L

2012-10-01

We hypothesize that the inner medulla of the kangaroo rat Dipodomys merriami, a desert rodent that concentrates its urine to over 6,000 mosmol/kg H(2)O, provides unique examples of architectural features necessary for production of highly concentrated urine. To investigate this architecture, inner medullary vascular segments in the outer inner medulla were assessed with immunofluorescence and digital reconstructions from tissue sections. Descending vasa recta (DVR) expressing the urea transporter UT-B and the water channel aquaporin 1 lie at the periphery of groups of collecting ducts (CDs) that coalesce in their descent through the inner medulla. Ascending vasa recta (AVR) lie inside and outside groups of CDs. DVR peel away from vascular bundles at a uniform rate as they descend the inner medulla, and feed into networks of AVR that are associated with organized clusters of CDs. These AVR form interstitial nodal spaces, with each space composed of a single CD, two AVR, and one or more ascending thin limbs or prebend segments, an architecture that may lead to solute compartmentation and fluid fluxes essential to the urine concentrating mechanism. Although we have identified several apparent differences, the tubulovascular architecture of the kangaroo rat inner medulla is remarkably similar to that of the Munich Wistar rat at the level of our analyses. More detailed studies are required for identifying interspecies functional differences.

Fabrication and dispersion evaluation of single-wall carbon nanotubes produced by FH-arc discharge method.

PubMed

Chen, B; Zhao, X; Inoue, S; Ando, Y

2010-06-01

In this work, we produced SWNTs by a hydrogen DC arc discharge with evaporation of carbon anode containing 1 at% Fe catalyst in H2-Ar mixture gas. This was named as FH-arc discharge method. The as-grown SWNTs synthesized by FH-arc discharge method have high crystallinity. An oxidation purification process of as-grown SWNTs with H2O2 has been developed to remove the coexisting Fe catalyst nanoparticles. As a result, SWNTs with purity higher than 90 at% have been achieved. To exhibit remarkable characteristics, CNTs should be separated from the bundles and kept in homogeneous and stable suspensions. For this purpose, the SWNTs prepared by FH-arc discharge method also have been treated by Nanomizer process with some surfactants. SPM images showed that the SWNTs bundles had become thinner and shorter.

Fast and reliable method of conductive carbon nanotube-probe fabrication for scanning probe microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dremov, Vyacheslav, E-mail: dremov@issp.ac.ru; Fedorov, Pavel; Grebenko, Artem

2015-05-15

We demonstrate the procedure of scanning probe microscopy (SPM) conductive probe fabrication with a single multi-walled carbon nanotube (MWNT) on a silicon cantilever pyramid. The nanotube bundle reliably attached to the metal-covered pyramid is formed using dielectrophoresis technique from the MWNT suspension. It is shown that the dimpled aluminum sample can be used both for shortening/modification of the nanotube bundle by applying pulse voltage between the probe and the sample and for controlling the probe shape via atomic force microscopy imaging the sample. Carbon nanotube attached to cantilever covered with noble metal is suitable for SPM imaging in such modulationmore » regimes as capacitance contrast microscopy, Kelvin probe microscopy, and scanning gate microscopy. The majority of such probes are conductive with conductivity not degrading within hours of SPM imaging.« less

Advantages and Disadvantages of Transtibial, Anteromedial Portal, and Outside-In Femoral Tunnel Drilling in Single-Bundle Anterior Cruciate Ligament Reconstruction: A Systematic Review.

PubMed

Robin, Brett N; Jani, Sunil S; Marvil, Sean C; Reid, John B; Schillhammer, Carl K; Lubowitz, James H

2015-07-01

Controversy exists regarding the best method for creating the knee anterior cruciate ligament (ACL) femoral tunnel or socket. The purpose of this study was to systematically review the risks, benefits, advantages, and disadvantages of the endoscopic transtibial (TT) technique, anteromedial portal technique, outside-in technique, and outside-in retrograde drilling technique for creating the ACL femoral tunnel. A PubMed search of English-language studies published between January 1, 2000, and February 17, 2014, was performed using the following keywords: "anterior cruciate ligament" AND "femoral tunnel." Included were studies reporting risks, benefits, advantages, and/or disadvantages of any ACL femoral technique. In addition, references of included articles were reviewed to identify potential studies missed in the original search. A total of 27 articles were identified through the search. TT technique advantages include familiarity and proven long-term outcomes; disadvantages include the risk of nonanatomic placement because of constrained (TT) drilling. Anteromedial portal technique advantages include unconstrained anatomic placement; disadvantages include technical challenges, short tunnels or sockets, and posterior-wall blowout. Outside-in technique advantages include unconstrained anatomic placement; disadvantages include the need for 2 incisions. Retrograde drilling technique advantages include unconstrained anatomic placement, as well as all-epiphyseal drilling in skeletally immature patients; disadvantages include the need for fluoroscopy for all-epiphyseal drilling. There is no one, single, established "gold-standard" technique for creation of the ACL femoral socket. Four accepted techniques show diverse and subjective advantages, disadvantages, risks, and benefits. Level V, systematic review of Level II through V evidence. Copyright © 2015 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Steady-state stiffness of utricular hair cells depends on macular location and hair bundle structure.

PubMed

Spoon, Corrie; Moravec, W J; Rowe, M H; Grant, J W; Peterson, E H

2011-12-01

Spatial and temporal properties of head movement are encoded by vestibular hair cells in the inner ear. One of the most striking features of these receptors is the orderly structural variation in their mechanoreceptive hair bundles, but the functional significance of this diversity is poorly understood. We tested the hypothesis that hair bundle structure is a significant contributor to hair bundle mechanics by comparing structure and steady-state stiffness of 73 hair bundles at varying locations on the utricular macula. Our first major finding is that stiffness of utricular hair bundles varies systematically with macular locus. Stiffness values are highest in the striola, near the line of hair bundle polarity reversal, and decline exponentially toward the medial extrastriola. Striolar bundles are significantly more stiff than those in medial (median: 8.9 μN/m) and lateral (2.0 μN/m) extrastriolae. Within the striola, bundle stiffness is greatest in zone 2 (106.4 μN/m), a band of type II hair cells, and significantly less in zone 3 (30.6 μN/m), which contains the only type I hair cells in the macula. Bathing bundles in media that break interciliary links produced changes in bundle stiffness with predictable time course and magnitude, suggesting that links were intact in our standard media and contributed normally to bundle stiffness during measurements. Our second major finding is that bundle structure is a significant predictor of steady-state stiffness: the heights of kinocilia and the tallest stereocilia are the most important determinants of bundle stiffness. Our results suggest 1) a functional interpretation of bundle height variability in vertebrate vestibular organs, 2) a role for the striola in detecting onset of head movement, and 3) the hypothesis that differences in bundle stiffness contribute to diversity in afferent response dynamics.

Steady-state stiffness of utricular hair cells depends on macular location and hair bundle structure

PubMed Central

Spoon, Corrie; Moravec, W. J.; Rowe, M. H.; Grant, J. W.

2011-01-01

Spatial and temporal properties of head movement are encoded by vestibular hair cells in the inner ear. One of the most striking features of these receptors is the orderly structural variation in their mechanoreceptive hair bundles, but the functional significance of this diversity is poorly understood. We tested the hypothesis that hair bundle structure is a significant contributor to hair bundle mechanics by comparing structure and steady-state stiffness of 73 hair bundles at varying locations on the utricular macula. Our first major finding is that stiffness of utricular hair bundles varies systematically with macular locus. Stiffness values are highest in the striola, near the line of hair bundle polarity reversal, and decline exponentially toward the medial extrastriola. Striolar bundles are significantly more stiff than those in medial (median: 8.9 μN/m) and lateral (2.0 μN/m) extrastriolae. Within the striola, bundle stiffness is greatest in zone 2 (106.4 μN/m), a band of type II hair cells, and significantly less in zone 3 (30.6 μN/m), which contains the only type I hair cells in the macula. Bathing bundles in media that break interciliary links produced changes in bundle stiffness with predictable time course and magnitude, suggesting that links were intact in our standard media and contributed normally to bundle stiffness during measurements. Our second major finding is that bundle structure is a significant predictor of steady-state stiffness: the heights of kinocilia and the tallest stereocilia are the most important determinants of bundle stiffness. Our results suggest 1) a functional interpretation of bundle height variability in vertebrate vestibular organs, 2) a role for the striola in detecting onset of head movement, and 3) the hypothesis that differences in bundle stiffness contribute to diversity in afferent response dynamics. PMID:21918003

Interventions to Reduce the Incidence of Hospital-Onset Clostridium difficile Infection: An Agent-Based Modeling Approach to Evaluate Clinical Effectiveness in Adult Acute Care Hospitals.

PubMed

Barker, Anna K; Alagoz, Oguzhan; Safdar, Nasia

2018-04-03

Despite intensified efforts to reduce hospital-onset Clostridium difficile infection (HO-CDI), its clinical and economic impacts continue to worsen. Many institutions have adopted bundled interventions that vary considerably in composition, strength of evidence, and effectiveness. Considerable gaps remain in our knowledge of intervention effectiveness and disease transmission, which hinders HO-CDI prevention. We developed an agent-based model of C. difficile transmission in a 200-bed adult hospital using studies from the literature, supplemented with primary data collection. The model includes an environmental component and 4 distinct agent types: patients, visitors, nurses, and physicians. We used the model to evaluate the comparative clinical effectiveness of 9 single interventions and 8 multiple-intervention bundles at reducing HO-CDI and asymptomatic C. difficile colonization. Daily cleaning with sporicidal disinfectant and C. difficile screening at admission were the most effective single-intervention strategies, reducing HO-CDI by 68.9% and 35.7%, respectively (both P < .001). Combining these interventions into a 2-intervention bundle reduced HO-CDI by 82.3% and asymptomatic hospital-onset colonization by 90.6% (both, P < .001). Adding patient hand hygiene to healthcare worker hand hygiene reduced HO-CDI rates an additional 7.9%. Visitor hand hygiene and contact precaution interventions did not reduce HO-CDI, compared with baseline. Excluding those strategies, healthcare worker contact precautions were the least effective intervention at reducing hospital-onset colonization and infection. Identifying and managing the vast hospital reservoir of asymptomatic C. difficile by screening and daily cleaning with sporicidal disinfectant are high-yield strategies. These findings provide much-needed data regarding which interventions to prioritize for optimal C. difficile control.

Terrestrial multi-view photogrammetry for landslide monitoring

NASA Astrophysics Data System (ADS)

Stumpf, A.; Malet, J.; Allemand, P.; Skupinski, G.; Pierrot-Deseilligny, M.

2013-12-01

Multi-view stereo (MVS) surface reconstruction from large photo collections is being increasingly used for geoscience applications, and a number of different software solution and processing streamlines have been suggested. Open source libraries to perform feature point extraction, pose estimation, bundle adjustment and dense matching are available providing high quality results at low costs, and transparency of the implemented algorithms. Within the computer vision community benchmark datasets with toy examples and architectural scenes are frequently used to evaluate dense matching algorithms but relatively few studies have addressed the evaluation of complete processing pipelines for complex natural landscapes such as landslides developed in high mountain terrains. In order to obtain surface displacement maps of an active landslide (Super-Sauze, Southern French Alps) from multi-temporal terrestrial photographs over a period of three years, this work targeted the evaluation of three different non-commercial processing pipelines. The tested packages include VisualSfM[1], CMVS-PMVS [2], Apero and MicMac [URL]. The image acquisition focused on either subparts of the landslide (toe, main scarp) or targeted the reconstruction of a global model of the entire landslide. All images were processed with three different pipelines namely VisualSfM + CMVS-PMVS, Apero + CMVS-PMVS and Apero + MicMac and the resulting point clouds were evaluated with terrestrial and airborne LiDAR. Our results show that all multi-view stereo pipelines provide useful results to quantify surface displacement at accuracies between 1-10 cm depending on the acquisition geometry and the object distance. For pose estimation and bundle adjustment, Apero is the more accurate and versatile tool allowing the use of more sophisticated lens models and the direct integration of ground control points in the bundle adjustment. The dense matching algorithms with MicMac enables the reconstruction of denser point clouds, with fewer outliers, better spatial coverage and at lower computational costs, whereas CMVS-PMVS requires less manual tuning and produces fewer artifacts at discontinuities and areas with very low incidence angles. Change detection among the multi-temporal photogrammetric point clouds allowed to measure surface displacement rates greater than 1 m.yr-1 at the landslide toe, and greater than 3 m.yr-1 in the upper most active landslide part, indicating and important mass-accumulation in the central part. Large low frequency rockfall dominate the mass wasting process at the main scarp when compared to erosive retrogression. The study demonstrates that MVS has a great potential to replace LiDAR surveys for operational landslide monitoring providing comparable accuracies at significantly lower logistic and material costs. However, an optimal acquisition geometry and parameterization of the processing algorithms are important factors for its successful application and some recommendations, potential pitfalls and limitations are highlighted. [1] C. Wu, Towards Linear-time Incremental Structure from Motion, Internat. Conf. on 3D Vision, University of Washington, Seattle, USA, 2013. [2] Y. Furukawa and J. Ponce, "Accurate, Dense, and Robust Multiview Stereopsis," Pattern Analysis and Machine Intelligence, IEEE Transactions on, 32, pp. 1362-1376, 2010.

Force-Induced Unravelling of DNA Origami.

PubMed

Engel, Megan C; Smith, David M; Jobst, Markus A; Sajfutdinow, Martin; Liedl, Tim; Romano, Flavio; Rovigatti, Lorenzo; Louis, Ard A; Doye, Jonathan P K

2018-05-31

The mechanical properties of DNA nanostructures are of widespread interest as applications that exploit their stability under constant or intermittent external forces become increasingly common. We explore the force response of DNA origami in comprehensive detail by combining AFM single molecule force spectroscopy experiments with simulations using oxDNA, a coarse-grained model of DNA at the nucleotide level, to study the unravelling of an iconic origami system: the Rothemund tile. We contrast the force-induced melting of the tile with simulations of an origami 10-helix bundle. Finally, we simulate a recently-proposed origami biosensor, whose function takes advantage of origami behaviour under tension. We observe characteristic stick-slip unfolding dynamics in our force-extension curves for both the Rothemund tile and the helix bundle and reasonable agreement with experimentally observed rupture forces for these systems. Our results highlight the effect of design on force response: we observe regular, modular unfolding for the Rothemund tile that contrasts with strain-softening of the 10-helix bundle which leads to catastropic failure under monotonically increasing force. Further, unravelling occurs straightforwardly from the scaffold ends inwards for the Rothemund tile, while the helix bundle unfolds more nonlinearly. The detailed visualization of the yielding events provided by simulation allows preferred pathways through the complex unfolding free-energy landscape to be mapped, as a key factor in determining relative barrier heights is the extensional release per base pair broken. We shed light on two important questions: how stable DNA nanostructures are under external forces; and what design principles can be applied to enhance stability.

Shear and friction between carbon nanotubes in bundles and yarns.

PubMed

Paci, Jeffrey T; Furmanchuk, Al'ona; Espinosa, Horacio D; Schatz, George C

2014-11-12

We perform a detailed density functional theory assessment of the factors that determine shear interactions between carbon nanotubes (CNTs) within bundles and in related CNT and graphene structures including yarns, providing an explanation for the shear force measured in recent experiments (Filleter, T. etal. Nano Lett. 2012, 12, 73). The potential energy barriers separating AB stacked structures are found to be irrelevant to the shear analysis for bundles and yarns due to turbostratic stacking, and as a result, the tube-tube shear strength for pristine CNTs is estimated to be <0.24 MPa, that is, extremely small. Instead, it is pinning due to the presence of defects and functional groups at the tube ends that primarily cause resistance to shear when bundles are fractured in weak vacuum (∼10(-5) Torr). Such defects and groups are estimated to involve 0.55 eV interaction energies on average, which is much larger than single-atom vacancy defects (approximately 0.039 eV). Furthermore, because graphitic materials are stiff they have large coherence lengths, and this means that push-pull effects result in force cancellation for vacancy and other defects that are internal to the CNTs. Another important factor is the softness of cantilever structures relative to the stiff CNTs in the experiments, as this contributes to elastic instability transitions that account for significant dissipation during shear that has been observed. The application of these results to the mechanical behavior of yarns is discussed, providing general guidelines for the manufacture of strong yarns composed of CNTs.

Structure of single-wall carbon nanotubes purified and cut using polymer

NASA Astrophysics Data System (ADS)

Zhang, M.; Yudasaka, M.; Koshio, A.; Jabs, C.; Ichihashi, T.; Iijima, S.

2002-01-01

Following on from our previous report that a monochlorobenzene solution of polymethylmethacrylate is useful for purifying and cutting single-wall carbon nanotubes (SWNTs) and thinning SWNT bundles, we show in this report that polymer and residual amorphous carbon can be removed by burning in oxygen gas. The SWNTs thus obtained had many holes (giving them a worm-eaten look) and were thermally unstable. Such severe damage caused by oxidation is unusual for SWNTs; we think that they were chemically damaged during ultrasonication in the monochlorobenzene solution of polymethylmethacrylate.

Preferential destruction of metallic single-walled carbon nanotubes by laser irradiation.

PubMed

Huang, Houjin; Maruyama, Ryuichiro; Noda, Kazuhiro; Kajiura, Hisashi; Kadono, Koji

2006-04-13

Upon laser irradiation in air, metallic single-walled carbon nanotubes (SWNTs) in carbon nanotube thin film can be destroyed in preference to their semiconducting counterparts when the wavelength and power intensity of the irradiation are appropriate and the carbon nanotubes are not heavily bundled. Our method takes advantage of these two species' different rates of photolysis-assisted oxidation, creating the possibility of defining the semiconducting portions of carbon nanotube (CNT) networks using optical lithography, particularly when constructing all-CNT FETs (without metal electrodes) in the future.

Shadow-free single-pixel imaging

NASA Astrophysics Data System (ADS)

Li, Shunhua; Zhang, Zibang; Ma, Xiao; Zhong, Jingang

2017-11-01

Single-pixel imaging is an innovative imaging scheme and receives increasing attention in recent years, for it is applicable for imaging at non-visible wavelengths and imaging under weak light conditions. However, as in conventional imaging, shadows would likely occur in single-pixel imaging and sometimes bring negative effects in practical uses. In this paper, the principle of shadows occurrence in single-pixel imaging is analyzed, following which a technique for shadows removal is proposed. In the proposed technique, several single-pixel detectors are used to detect the backscattered light at different locations so that the shadows in the reconstructed images corresponding to each detector shadows are complementary. Shadow-free reconstruction can be derived by fusing the shadow-complementary images using maximum selection rule. To deal with the problem of intensity mismatch in image fusion, we put forward a simple calibration. As experimentally demonstrated, the technique is able to reconstruct monochromatic and full-color shadow-free images.

The midline-based nasolabial transposition (MNT) flap: an original single-stage technique for nasal tip reconstruction.

PubMed

Beustes-Stefanelli, Matthieu; O'Toole, Greg; Schertenleib, Pierre

2015-04-01

Nasolabial flaps based on the lateral side of the nose for the reconstruction of lateral nasal defects in a single-stage procedure have been described. Similarly, in midline defects, nasolabial flaps can be used but a 2-stage procedure is classically required. The Midline-based Nasolabial Transposition (MNT) flap is presented as a new single-stage procedure for nasal tip reconstruction. Between 2009 and 2011, an MNT flap was used as a single-stage procedure in 3 cases of large nasal defects of the tip where the forehead flap was either contraindicated or rejected as an option by the patient. There were no complications and a satisfactory aesthetic result was achieved in all cases. The MNT flap is a new single-stage procedure for large nasal tip defects and as such represents an interesting alternative to the classical 2-stage forehead and nasolabial flaps, especially in elderly patients.

Single-shot three-dimensional reconstruction based on structured light line pattern

NASA Astrophysics Data System (ADS)

Wang, ZhenZhou; Yang, YongMing

2018-07-01

Reconstruction of the object by single-shot is of great importance in many applications, in which the object is moving or its shape is non-rigid and changes irregularly. In this paper, we propose a single-shot structured light 3D imaging technique that calculates the phase map from the distorted line pattern. This technique makes use of the image processing techniques to segment and cluster the projected structured light line pattern from one single captured image. The coordinates of the clustered lines are extracted to form a low-resolution phase matrix which is then transformed to full-resolution phase map by spline interpolation. The 3D shape of the object is computed from the full-resolution phase map and the 2D camera coordinates. Experimental results show that the proposed method was able to reconstruct the three-dimensional shape of the object robustly from one single image.

Associations Among Quadriceps Strength and Rate of Torque Development 6 Weeks Post Anterior Cruciate Ligament Reconstruction and Future Hop and Vertical Jump Performance: A Prospective Cohort Study.

PubMed

Pua, Yong-Hao; Mentiplay, Benjamin F; Clark, Ross A; Ho, Jia-Ying

2017-11-01

Study Design Prospective cohort. Background Quadriceps strength is associated with hop distance and jump height in persons who have undergone anterior cruciate ligament (ACL) reconstruction. However, it is unknown whether the ability to rapidly generate quadriceps torque in the early phase of recovery is associated with future hopping and jumping performance in this population. Objective To evaluate the prospective associations among quadriceps strength and rate of torque development (RTD) and single-leg hop for distance, vertical jump height, vertical ground reaction force (vGRF), and vertical force loading rate during a landing task in persons who have undergone ACL reconstruction. Methods Seventy patients with unilateral ACL reconstruction participated. At 6 weeks post ACL reconstruction, isometric quadriceps strength and RTD were measured using a dynamometer. At 6 months following ACL reconstruction, patients performed the single-leg hop for distance test. Patients also performed the single-leg vertical jump test on a force plate that measured maximum jump height, vGRF, and average loading rate during landing. Results Both quadriceps strength and RTD at 6 weeks post ACL reconstruction were associated with all hopping and jumping measures at 6 months post ACL reconstruction (P≤.04). Single-leg hop distance was associated more closely with quadriceps strength than with quadriceps RTD (P = .05), and vertical jump height and vGRF measures were associated more closely with quadriceps RTD than with quadriceps strength (P = .05 and P<.01, respectively). Both quadriceps measures were associated with loading rate. Conclusion Quadriceps strength and RTD are complementary but distinct predictors of future hopping and jumping performance in persons who have undergone ACL reconstruction. These findings may contribute to improved rehabilitation of patients who are at risk for poor jumping/hopping performance and abnormal knee loading. J Orthop Sports Phys Ther 2017;47(11):845-852. Epub 13 Oct 2017. doi:10.2519/jospt.2017.7133.

Rapid 3D Reconstruction for Image Sequence Acquired from UAV Camera

PubMed Central

Qu, Yufu; Huang, Jianyu; Zhang, Xuan

2018-01-01

In order to reconstruct three-dimensional (3D) structures from an image sequence captured by unmanned aerial vehicles’ camera (UAVs) and improve the processing speed, we propose a rapid 3D reconstruction method that is based on an image queue, considering the continuity and relevance of UAV camera images. The proposed approach first compresses the feature points of each image into three principal component points by using the principal component analysis method. In order to select the key images suitable for 3D reconstruction, the principal component points are used to estimate the interrelationships between images. Second, these key images are inserted into a fixed-length image queue. The positions and orientations of the images are calculated, and the 3D coordinates of the feature points are estimated using weighted bundle adjustment. With this structural information, the depth maps of these images can be calculated. Next, we update the image queue by deleting some of the old images and inserting some new images into the queue, and a structural calculation of all the images can be performed by repeating the previous steps. Finally, a dense 3D point cloud can be obtained using the depth–map fusion method. The experimental results indicate that when the texture of the images is complex and the number of images exceeds 100, the proposed method can improve the calculation speed by more than a factor of four with almost no loss of precision. Furthermore, as the number of images increases, the improvement in the calculation speed will become more noticeable. PMID:29342908

Rapid 3D Reconstruction for Image Sequence Acquired from UAV Camera.

PubMed

Qu, Yufu; Huang, Jianyu; Zhang, Xuan

2018-01-14

In order to reconstruct three-dimensional (3D) structures from an image sequence captured by unmanned aerial vehicles' camera (UAVs) and improve the processing speed, we propose a rapid 3D reconstruction method that is based on an image queue, considering the continuity and relevance of UAV camera images. The proposed approach first compresses the feature points of each image into three principal component points by using the principal component analysis method. In order to select the key images suitable for 3D reconstruction, the principal component points are used to estimate the interrelationships between images. Second, these key images are inserted into a fixed-length image queue. The positions and orientations of the images are calculated, and the 3D coordinates of the feature points are estimated using weighted bundle adjustment. With this structural information, the depth maps of these images can be calculated. Next, we update the image queue by deleting some of the old images and inserting some new images into the queue, and a structural calculation of all the images can be performed by repeating the previous steps. Finally, a dense 3D point cloud can be obtained using the depth-map fusion method. The experimental results indicate that when the texture of the images is complex and the number of images exceeds 100, the proposed method can improve the calculation speed by more than a factor of four with almost no loss of precision. Furthermore, as the number of images increases, the improvement in the calculation speed will become more noticeable.

Statistical shape model-based reconstruction of a scaled, patient-specific surface model of the pelvis from a single standard AP x-ray radiograph

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng Guoyan

2010-04-15

Purpose: The aim of this article is to investigate the feasibility of using a statistical shape model (SSM)-based reconstruction technique to derive a scaled, patient-specific surface model of the pelvis from a single standard anteroposterior (AP) x-ray radiograph and the feasibility of estimating the scale of the reconstructed surface model by performing a surface-based 3D/3D matching. Methods: Data sets of 14 pelvises (one plastic bone, 12 cadavers, and one patient) were used to validate the single-image based reconstruction technique. This reconstruction technique is based on a hybrid 2D/3D deformable registration process combining a landmark-to-ray registration with a SSM-based 2D/3D reconstruction.more » The landmark-to-ray registration was used to find an initial scale and an initial rigid transformation between the x-ray image and the SSM. The estimated scale and rigid transformation were used to initialize the SSM-based 2D/3D reconstruction. The optimal reconstruction was then achieved in three stages by iteratively matching the projections of the apparent contours extracted from a 3D model derived from the SSM to the image contours extracted from the x-ray radiograph: Iterative affine registration, statistical instantiation, and iterative regularized shape deformation. The image contours are first detected by using a semiautomatic segmentation tool based on the Livewire algorithm and then approximated by a set of sparse dominant points that are adaptively sampled from the detected contours. The unknown scales of the reconstructed models were estimated by performing a surface-based 3D/3D matching between the reconstructed models and the associated ground truth models that were derived from a CT-based reconstruction method. Such a matching also allowed for computing the errors between the reconstructed models and the associated ground truth models. Results: The technique could reconstruct the surface models of all 14 pelvises directly from the landmark-based initialization. Depending on the surface-based matching techniques, the reconstruction errors were slightly different. When a surface-based iterative affine registration was used, an average reconstruction error of 1.6 mm was observed. This error was increased to 1.9 mm, when a surface-based iterative scaled rigid registration was used. Conclusions: It is feasible to reconstruct a scaled, patient-specific surface model of the pelvis from single standard AP x-ray radiograph using the present approach. The unknown scale of the reconstructed model can be estimated by performing a surface-based 3D/3D matching.« less

Moisture separator reheater with round tube bundle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byerley, W. M.

1984-11-27

A moisture separator reheater having a central chamber with cylindrical wall protions and a generally round tube bundle, the tube bundle having arcuate plates disposed on each side of the bundle which form a wrapper on each side of the bundle and having a tongue and groove juncture between the wrapper and cylindrical wall portions to provide a seal therebetween and a track for installing and removing the tube bundle from the central chamber.

["Habitual" left branch block alternating with 2 "disguised" bracnch block].

PubMed

Lévy, S; Jullien, G; Mathieu, P; Mostefa, S; Gérard, R

1976-10-01

Two cases of alternating left bundle branch block and "masquerading block" (with left bundle branch morphology in the stnadard leads and right bundle branch block morphology in the precordial leads) were studied by serial tracings and his bundle electrocardiography. In case 1 "the masquerading" block was associated with a first degree AV block related to a prolongation of HV interval. This case is to our knowledge the first cas of alternating bundle branch block in which his bundle activity was recorded in man. In case 2, the patient had atrial fibrilation and His bundle recordings were performed while differents degrees of left bundle branch block were present: The mechanism of the alternation and the concept of "masquerading" block are discussed. It is suggested that this type of block represents a right bundle branch block associated with severe lesions of the "left system".

Anterior Cruciate Ligament-Derived Stem Cells Transduced With BMP2 Accelerate Graft-Bone Integration After ACL Reconstruction.

PubMed

Kawakami, Yohei; Takayama, Koji; Matsumoto, Tomoyuki; Tang, Ying; Wang, Bing; Mifune, Yutaka; Cummins, James H; Warth, Ryan J; Kuroda, Ryosuke; Kurosaka, Masahiro; Fu, Freddie H; Huard, Johnny

2017-03-01

Strong graft-bone integration is a prerequisite for successful graft remodeling after reconstruction of the anterior cruciate ligament (ACL) using soft tissue grafts. Novel strategies to accelerate soft tissue graft-bone integration are needed to reduce the need for bone-tendon-bone graft harvest, reduce patient convalescence, facilitate rehabilitation, and reduce total recovery time after ACL reconstruction. The application of ACL-derived stem cells with enhanced expression of bone morphogenetic protein 2 (BMP2) onto soft tissue grafts in the form of cell sheets will both accelerate and improve the quality of graft-bone integration after ACL reconstruction in a rat model. Controlled laboratory study. ACL-derived CD34+ cells were isolated from remnant human ACL tissues, virally transduced to express BMP2, and embedded within cell sheets. In a rat model of ACL injury, bilateral single-bundle ACL reconstructions were performed, in which cell sheets were wrapped around tendon autografts before reconstruction. Four groups containing a total of 48 rats (96 knees) were established (n = 12 rats; 24 knees per group): CD34+BMP2 (100%), CD34+BMP2 (25%), CD34+ (untransduced), and a control group containing no cells. Six rats from each group were euthanized 2 and 4 weeks after surgery, and each graft was harvested for immunohistochemical and histological analyses. The remaining 6 rats in each group were euthanized at 4 and 8 weeks to evaluate in situ tensile load to failure in each femur-graft-tibia complex. In vitro, BMP2 transduction promoted the osteogenic differentiation of ACL-derived CD34+ cells while retaining their intrinsic multipotent capabilities. Osteoblast densities were greatest in the BMP2 (100%) and BMP2 (25%) groups. Bone tunnels in the CD34+BMP2 (100%) and CD34+BMP2 (25%) groups had the smallest cross-sectional areas according to micro-computed tomography analyses. Graft-bone integration occurred most rapidly in the CD34+BMP2 (25%) group. Tensile load to failure was significantly greater in the groups containing stem cells at 4 and 8 weeks after surgery. Tensile strength was greatest in the CD34+BMP2 (100%) group at 4 weeks, and in the CD34+BMP2 (25%) group at 8 weeks. ACL-derived CD34+ cells transduced with BMP2 accelerated graft-bone integration after ACL reconstruction using soft tissue autografts in a rat model, as evidenced by improved histological appearance and graft-bone interface biology along with tensile load to failure at each time point up to 8 weeks after surgery. A primary disadvantage of using soft tissue grafts for ACL reconstruction is the prolonged time required for bony ingrowth, which delays the initiation of midsubstance graft remodeling. The lack of consistent correlation between the appearance of a "healed" ACL on postoperative magnetic resonance imaging and readiness to return to sport results in athletes being released to sport before the graft is ready to handle high-intensity loading. Therefore, it is desirable to identify strategies that accelerate graft-bone integration, which would reduce the time to biologic fixation, improve the reliability of biologic fixation, allow for accelerated rehabilitation, and potentially reduce the incidence of early graft pullout and late midsubstance failure.

SCNS: a graphical tool for reconstructing executable regulatory networks from single-cell genomic data.

PubMed

Woodhouse, Steven; Piterman, Nir; Wintersteiger, Christoph M; Göttgens, Berthold; Fisher, Jasmin

2018-05-25

Reconstruction of executable mechanistic models from single-cell gene expression data represents a powerful approach to understanding developmental and disease processes. New ambitious efforts like the Human Cell Atlas will soon lead to an explosion of data with potential for uncovering and understanding the regulatory networks which underlie the behaviour of all human cells. In order to take advantage of this data, however, there is a need for general-purpose, user-friendly and efficient computational tools that can be readily used by biologists who do not have specialist computer science knowledge. The Single Cell Network Synthesis toolkit (SCNS) is a general-purpose computational tool for the reconstruction and analysis of executable models from single-cell gene expression data. Through a graphical user interface, SCNS takes single-cell qPCR or RNA-sequencing data taken across a time course, and searches for logical rules that drive transitions from early cell states towards late cell states. Because the resulting reconstructed models are executable, they can be used to make predictions about the effect of specific gene perturbations on the generation of specific lineages. SCNS should be of broad interest to the growing number of researchers working in single-cell genomics and will help further facilitate the generation of valuable mechanistic insights into developmental, homeostatic and disease processes.

The Evolving Treatment Patterns of NCAA Division I Football Players by Orthopaedic Team Physicians Over the Past Decade, 2008-2016.

PubMed

Carver, Trevor J; Schrock, John B; Kraeutler, Matthew J; McCarty, Eric C

Previous studies have analyzed the treatment patterns used to manage injuries in National Collegiate Athletic Association (NCAA) Division I football players. Treatment patterns used to manage injuries in NCAA Division I football players will have changed over the study period. Descriptive epidemiology study. Level 5. The head orthopaedic team physicians for all 128 NCAA Division I football teams were asked to complete a survey containing questions regarding experience as team physician, medical coverage of the team, reimbursement issues, and treatment preferences for some of the most common injuries occurring in football players. Responses from the current survey were compared with responses from the same survey sent to NCAA Division I team physicians in 2008. Responses were received from 111 (111/119, 93%) NCAA Division I orthopaedic team physicians in 2008 and 115 (115/128, 90%) orthopaedic team physicians between April 2016 and April 2017. The proportion of team physicians who prefer a patellar tendon autograft for primary anterior cruciate ligament reconstruction (ACLR) increased from 67% in 2008 to 83% in 2016 ( P < 0.001). The proportion of team physicians who perform anterior shoulder stabilization arthroscopically increased from 69% in 2008 to 93% in 2016 ( P < 0.0001). Of team physicians who perform surgery for grade III posterior cruciate ligament (PCL) injuries, the proportion who use the arthroscopic single-bundle technique increased from 49% in 2008 to 83% in 2016 ( P < 0.0001). The proportion of team physicians who use Toradol injections prior to a game to help with nagging injuries decreased from 62% in 2008 to 26% in 2016 ( P < 0.0001). Orthopaedic physicians changed their injury treatment preferences for NCAA Division I football players over the study period. In particular, physicians have changed their preferred techniques for ACLR, anterior shoulder stabilization, and PCL reconstruction. Physicians have also become more conservative with pregame Toradol injections. These opinions may help guide treatment decisions and lead to better care of all athletes.

Three-dimensional noninvasive monitoring iodine-131 uptake in the thyroid using a modified Cerenkov luminescence tomography approach.

PubMed

Hu, Zhenhua; Ma, Xiaowei; Qu, Xiaochao; Yang, Weidong; Liang, Jimin; Wang, Jing; Tian, Jie

2012-01-01

Cerenkov luminescence tomography (CLT) provides the three-dimensional (3D) radiopharmaceutical biodistribution in small living animals, which is vital to biomedical imaging. However, existing single-spectral and multispectral methods are not very efficient and effective at reconstructing the distribution of the radionuclide tracer. In this paper, we present a semi-quantitative Cerenkov radiation spectral characteristic-based source reconstruction method named the hybrid spectral CLT, to efficiently reconstruct the radionuclide tracer with both encouraging reconstruction results and less acquisition and image reconstruction time. We constructed the implantation mouse model implanted with a 400 µCi Na(131)I radioactive source and the physiological mouse model received an intravenous tail injection of 400 µCi radiopharmaceutical Iodine-131 (I-131) to validate the performance of the hybrid spectral CLT and compared the reconstruction results, acquisition, and image reconstruction time with that of single-spectral and multispectral CLT. Furthermore, we performed 3D noninvasive monitoring of I-131 uptake in the thyroid and quantified I-131 uptake in vivo using hybrid spectral CLT. Results showed that the reconstruction based on the hybrid spectral CLT was more accurate in localization and quantification than using single-spectral CLT, and was more efficient in the in vivo experiment compared with multispectral CLT. Additionally, 3D visualization of longitudinal observations suggested that the reconstructed energy of I-131 uptake in the thyroid increased with acquisition time and there was a robust correlation between the reconstructed energy versus the gamma ray counts of I-131 (r(2) = 0.8240). The ex vivo biodistribution experiment further confirmed the I-131 uptake in the thyroid for hybrid spectral CLT. Results indicated that hybrid spectral CLT could be potentially used for thyroid imaging to evaluate its function and monitor its treatment for thyroid cancer.

Quantitative Susceptibility Mapping of Human Brain Reflects Spatial Variation in Tissue Composition

PubMed Central

Li, Wei; Wu, Bing; Liu, Chunlei

2011-01-01

Image phase from gradient echo MRI provides a unique contrast that reflects brain tissue composition variations, such as iron and myelin distribution. Phase imaging is emerging as a powerful tool for the investigation of functional brain anatomy and disease diagnosis. However, the quantitative value of phase is compromised by its nonlocal and orientation dependent properties. There is an increasing need for reliable quantification of magnetic susceptibility, the intrinsic property of tissue. In this study, we developed a novel and accurate susceptibility mapping method that is also phase-wrap insensitive. The proposed susceptibility mapping method utilized two complementary equations: (1) the Fourier relationship of phase and magnetic susceptibility; and (2) the first-order partial derivative of the first equation in the spatial frequency domain. In numerical simulation, this method reconstructed the susceptibility map almost free of streaking artifact. Further, the iterative implementation of this method allowed for high quality reconstruction of susceptibility maps of human brain in vivo. The reconstructed susceptibility map provided excellent contrast of iron-rich deep nuclei and white matter bundles from surrounding tissues. Further, it also revealed anisotropic magnetic susceptibility in brain white matter. Hence, the proposed susceptibility mapping method may provide a powerful tool for the study of brain physiology and pathophysiology. Further elucidation of anisotropic magnetic susceptibility in vivo may allow us to gain more insight into the white matter microarchitectures. PMID:21224002

77 FR 50746 - Self-Regulatory Organizations; NYSE Arca, Inc.; Order Approving a Proposed Rule Change Amending...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-22

... a single sheath can hold either one cross connect or several cross connects in multiples of six (e.g., six, twelve, eighteen or twenty-four cross connects). The Exchange proposes to charge a $500 initial... and install one cross connect between cabinets. For a bundle of six cross connects, the monthly charge...

Statistical spatio-temporal properties of the Laser MegaJoule speckle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le Cain, A.; Sajer, J. M.; Riazuelo, G.

2012-10-15

This paper investigates a statistical model to describe the spatial and temporal properties of hot spots generated by the superimposition of multiple laser beams. In the context of the Laser MegaJoule design, we introduce the formula for contrasts, trajectories and velocities of the speckle pattern. Single bundle of four beams, two-cones and three-cones configurations are considered. Statistical properties of the speckle in the zone where all the beams overlap are studied with different configurations of polarizations. These properties are shown to be very different from the case of one single bundle of four beams. The configuration of polarization has onlymore » a slight effect in the two-cones or three cones configuration. Indeed, the impact of the double polarization smoothing is reduced in the area in which all the beams overlap, while it is much more significant when they split. Moreover, the size of the hot-spots decreases as the number of laser beams increases, but we show that their velocity decreases. As a matter of fact, the maximal velocity of hot spots is found to be only about 10{sup -5} of the velocity of light and the integrated contrast is about 15% when the beams overlap.« less

Constructing spherical panoramas of a bladder phantom from endoscopic video using bundle adjustment

NASA Astrophysics Data System (ADS)

Soper, Timothy D.; Chandler, John E.; Porter, Michael P.; Seibel, Eric J.

2011-03-01

The high recurrence rate of bladder cancer requires patients to undergo frequent surveillance screenings over their lifetime following initial diagnosis and resection. Our laboratory is developing panoramic stitching software that would compile several minutes of cystoscopic video into a single panoramic image, covering the entire bladder, for review by an urolgist at a later time or remote location. Global alignment of video frames is achieved by using a bundle adjuster that simultaneously recovers both the 3D structure of the bladder as well as the scope motion using only the video frames as input. The result of the algorithm is a complete 360° spherical panorama of the outer surface. The details of the software algorithms are presented here along with results from both a virtual cystoscopy as well from real endoscopic imaging of a bladder phantom. The software successfully stitched several hundred video frames into a single panoramic with subpixel accuracy and with no knowledge of the intrinsic camera properties, such as focal length and radial distortion. In the discussion, we outline future work in development of the software as well as identifying factors pertinent to clinical translation of this technology.

Functional Single-Walled Carbon Nanotubes and Nanoengineered Networks for Organic- and Perovskite-Solar-Cell Applications.

PubMed

Barbero, David R; Stranks, Samuel D

2016-11-01

Carbon nanotubes have a variety of remarkable electronic and mechanical properties that, in principle, lend them to promising optoelectronic applications. However, the field has been plagued by heterogeneity in the distributions of synthesized tubes and uncontrolled bundling, both of which have prevented nanotubes from reaching their full potential. Here, a variety of recently demonstrated solution-processing avenues is presented, which may combat these challenges through manipulation of nanoscale structures. Recent advances in polymer-wrapping of single-walled carbon nanotubes (SWNTs) are shown, along with how the resulting nanostructures can selectively disperse tubes while also exploiting the favorable properties of the polymer, such as light-harvesting ability. New methods to controllably form nanoengineered SWNT networks with controlled nanotube placement are discussed. These nanoengineered networks decrease bundling, lower the percolation threshold, and enable a strong enhancement in charge conductivity compared to random networks, making them potentially attractive for optoelectronic applications. Finally, SWNT applications, to date, in organic and perovskite photovoltaics are reviewed, and insights as to how the aforementioned recent advancements can lead to improved device performance provided. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Satisfactory knee function after single-stage posterolateral corner reconstruction in the multi-ligament injured/dislocated knee using the anatomic single-graft technique.

PubMed

Sanders, Thomas L; Johnson, Nick R; Pareek, Ayoosh; Krych, Aaron J; Marx, Robert G; Stuart, Michael J; Levy, Bruce A

2018-04-01

Increasing importance has been placed on the posterolateral corner (PLC) in maintaining varus and rotational stability of the knee. The goal of this study was to evaluate knee function and clinical stability following a single-graft PLC reconstruction technique and identify factors associated with poor knee function. This study identified patients with a multi-ligament knee injury between 2006 and 2013. Patients who received a single-graft fibular collateral ligament and PLC reconstruction with a single-stage surgery during the study period and had a minimum follow-up of 2 years after surgery were included. Functional outcomes were assessed using Lysholm and IKDC scores. Varus and rotational knee laxity and range of motion were assessed using physical examination. The final study cohort included 61 patients who underwent PLC reconstruction using a single-graft technique. The mean IKDC score was 74.1 (± 22.3) and the mean Lysholm score was 80.3 (± 21.8) at mean follow-up of 3.8 years (range 2-9 years). Mean range of motion at final follow-up measured from 0° to 126° [range flexion: 95-145, range extension: 0-5]. Fifty-eight patients (95%) had grade 0 varus laxity in full knee extension, and 54 patients (88.5%) had grade 0 varus laxity at 30° of knee flexion. Female gender was associated with a lower postoperative IKDC score (p = 0.04). Surgical treatment of the PLC using a single-graft technique can result in satisfactory knee function and stable physical examination findings at minimum 2 years after surgery. Female gender was predictive of poor knee function after PLC reconstruction. Surgical treatment of PLC injuries should be individualized based on the timing of surgery, specific injured knee structures, and physical examination findings. This study helps validate the use of a single-graft technique for PLC reconstruction and can be used to help counsel patients about expected knee function after surgical treatment of PLC injuries. Level of evidence IV.

Videoendoscopic Single-Port Nipple-Sparing Mastectomy and Immediate Reconstruction

PubMed Central

Ozden, Burcu Celet; Agcaoglu, Orhan; Kecer, Mustafa; Ozmen, Vahit; Muslumanoglu, Mahmut; Igci, Abdullah

2014-01-01

Abstract Purpose: Single-incision videoendoscopic surgery has recently become popular as a result of the ongoing search for less invasive procedures. The aim of this study was to evaluate the safety and efficacy of endoscopic single-port nipple-sparing mastectomy, axillary lymphadenectomy, and immediate reconstruction in patients with breast cancer. Patients and Methods: From May 14, 2012 through January 23, 2013, 10 patients underwent videoendoscopic single-port nipple-sparing mastectomy and axillary dissection via a single, limited incision and immediate prosthetic reconstruction. Patient charts were reviewed, and demographic data, operative time, complications and pathology results were analyzed. Results: In all patients, videoendoscopic surgery was performed successfully. Of 10 patients, 7 were diagnosed as having invasive ductal carcinoma, 2 had a ductal carcinoma in situ, and 1 underwent bilateral prophylactic mastectomy. The weight of the resected gland was 300–650 g, with a mean of 420 g. There were no operative complications, and the mean operative time was 250 minutes (range, 160–330 minutes). One-stage reconstruction with implants was performed on 4 patients, whereas expanders were placed in the remaining 6. Surgical margins of all cases were pathologically negative, and there were no recurrences observed during the early follow-up period. Conclusions: Videoendoscopic single-port nipple-sparing mastectomy is technically feasible even in larger breasts, enabling immediate reconstruction with good cosmetic outcomes. However, further studies with larger clinical series and long-term follow-up are required to compare the safety and efficacy of the technique with those of the standard nipple-sparing mastectomy. PMID:24401140

Cations Modulate Actin Bundle Mechanics, Assembly Dynamics, and Structure.

PubMed

Castaneda, Nicholas; Zheng, Tianyu; Rivera-Jacquez, Hector J; Lee, Hyun-Ju; Hyun, Jaekyung; Balaeff, Alexander; Huo, Qun; Kang, Hyeran

2018-04-12

Actin bundles are key factors in the mechanical support and dynamic reorganization of the cytoskeleton. High concentrations of multivalent counterions promote bundle formation through electrostatic attraction between actin filaments that are negatively charged polyelectrolytes. In this study, we evaluate how physiologically relevant divalent cations affect the mechanical, dynamic, and structural properties of actin bundles. Using a combination of total internal reflection fluorescence microscopy, transmission electron microscopy, and dynamic light scattering, we demonstrate that divalent cations modulate bundle stiffness, length distribution, and lateral growth. Molecular dynamics simulations of an all-atom model of the actin bundle reveal specific actin residues coordinate cation-binding sites that promote the bundle formation. Our work suggests that specific cation interactions may play a fundamental role in the assembly, structure, and mechanical properties of actin bundles.

Spinal surgery: variations in health care costs and implications for episode-based bundled payments.

PubMed

Ugiliweneza, Beatrice; Kong, Maiying; Nosova, Kristin; Huang, Kevin T; Babu, Ranjith; Lad, Shivanand P; Boakye, Maxwell

2014-07-01

Retrospective, observational. To simulate what episodes of care in spinal surgery might look like in a bundled payment system and to evaluate the associated costs and characteristics. Episode-based payment bundling has received considerable attention as a potential method to help curb the rise in health care spending and is being investigated as a new payment model as part of the Affordable Care Act. Although earlier studies investigated bundled payments in a number of surgical settings, very few focused on spine surgery, specifically. We analyzed data from MarketScan. Patients were included in the study if they underwent cervical or lumbar spinal surgery during 2000-2009, had at least 2-year preoperative and 90-day postoperative follow-up data. Patients were grouped on the basis of their diagnosis-related group (DRG) and then tracked in simulated episodes-of-care/payment bundles that lasted for the duration of 30, 60, and 90 days after the discharge from the index-surgical hospitalization. The total cost associated with each episode-of-care duration was measured and characterized. A total of 196,918 patients met our inclusion criteria. Significant variation existed between DRGs, ranging from $11,180 (30-day bundle, DRG 491) to $107,642 (30-day bundle, DRG 456). There were significant cost variations within each individual DRG. Postdischarge care accounted for a relatively small portion of overall bundle costs (range, 4%-8% in 90-day bundles). Total bundle costs remained relatively flat as bundle-length increased (total average cost of 30-day bundle: $33,522 vs. $35,165 for 90-day bundle). Payments to hospitals accounted for the largest portion of bundle costs (76%). There exists significant variation in total health care costs for patients who undergo spinal surgery, even within a given DRG. Better characterization of impacts of a bundled payment system in spine surgery is important for understanding the costs of index procedure hospital, physician services, and postoperative care on potential future health care policy decision making. N/A.

Nurses' perceptions of a pressure ulcer prevention care bundle: a qualitative descriptive study.

PubMed

Roberts, Shelley; McInnes, Elizabeth; Wallis, Marianne; Bucknall, Tracey; Banks, Merrilyn; Chaboyer, Wendy

2016-01-01

Pressure ulcer prevention is a critical patient safety indicator for acute care hospitals. An innovative pressure ulcer prevention care bundle targeting patient participation in their care was recently tested in a cluster randomised trial in eight Australian hospitals. Understanding nurses' perspectives of such an intervention is imperative when interpreting results and translating evidence into practice. As part of a process evaluation for the main trial, this study assessed nurses' perceptions of the usefulness and impact of a pressure ulcer prevention care bundle intervention on clinical practice. This qualitative descriptive study involved semi-structured interviews with nursing staff at four Australian hospitals that were intervention sites for a cluster randomised trial testing a pressure ulcer prevention care bundle. Four to five participants were purposively sampled at each site. A trained interviewer used a semi-structured interview guide to question participants about their perceptions of the care bundle. Interviews were digitally recorded, transcribed and analysed using thematic analysis. Eighteen nurses from four hospitals participated in the study. Nurses' perceptions of the intervention are described in five themes: 1) Awareness of the pressure ulcer prevention care bundle and its similarity to current practice; 2) Improving awareness, communication and participation with the pressure ulcer prevention care bundle; 3) Appreciating the positive aspects of patient participation in care; 4) Perceived barriers to engaging patients in the pressure ulcer prevention care bundle; and 5) Partnering with nursing staff to facilitate pressure ulcer prevention care bundle implementation. Overall, nurses found the care bundle feasible and acceptable. They identified a number of benefits from the bundle, including improved communication, awareness and participation in pressure ulcer prevention care among patients and staff. However, nurses thought the care bundle was not appropriate or effective for all patients, such as those who were cognitively impaired. Perceived enablers to implementation of the bundle included facilitation through effective communication and dissemination of evidence about the care bundle; strong leadership and ability to influence staff behaviour; and simplicity of the care bundle.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kraus, A.; Garner, P.; Hanan, N.

Thermal-hydraulic simulations have been performed using computational fluid dynamics (CFD) for the highly-enriched uranium (HEU) design of the IVG.1M reactor at the Institute of Atomic Energy (IAE) at the National Nuclear Center (NNC) in the Republic of Kazakhstan. Steady-state simulations were performed for both types of fuel assembly (FA), i.e. the FA in rows 1 & 2 and the FA in row 3, as well as for single pins in those FA (600 mm and 800 mm pins). Both single pin calculations and bundle sectors have been simulated for the most conservative operating conditions corresponding to the 10 MW outputmore » power, which corresponds to a pin unit cell Reynolds number of only about 7500. Simulations were performed using the commercial code STAR-CCM+ for the actual twisted pin geometry as well as a straight-pin approximation. Various Reynolds-Averaged Navier-Stokes (RANS) turbulence models gave different results, and so some validation runs with a higher-fidelity Large Eddy Simulation (LES) code were performed given the lack of experimental data. These singled out the Realizable Two-Layer k-ε as the most accurate turbulence model for estimating surface temperature. Single-pin results for the twisted case, based on the average flow rate per pin and peak pin power, were conservative for peak clad surface temperature compared to the bundle results. Also the straight-pin calculations were conservative as compared to the twisted pin simulations, as expected, but the single-pin straight case was not always conservative with regard to the straight-pin bundle. This was due to the straight-pin temperature distribution being strongly influenced by the pin orientation, particularly near the outer boundary. The straight-pin case also predicted the peak temperature to be in a different location than the twisted-pin case. This is a limitation of the straight-pin approach. The peak temperature pin was in a different location from the peak power pin in every case simulated, and occurred at an inner pin just before the enrichment change. The 600 mm case demonstrated a peak clad surface temperature of 370.4 K, while the 800 mm case had a temperature of 391.6 K. These temperatures are well below the necessary temperatures for boiling to occur at the rated pressure. Fuel temperatures are also well below the melting point. Future bundle work will include simulations of the proposed low-enriched uranium (LEU) design. Two transient scenarios were also investigated for the single-pin geometries. Both were “model” problems that were focused on pure thermal-hydraulic behavior, and as such were simple power changes that did not incorporate neutron kinetics modeling. The first scenario was a high-power, ramp increase, while the second scenario was a low-power, step increase. A cylindrical RELAP model was also constructed to investigate its accuracy as compared to the higher-fidelity CFD. Comparisons between the two codes showed good agreement for peak temperatures in the fuel and at the cladding surface for both cases. In the step transient, temperatures at four axial levels were also computed. These showed greater but reasonable discrepancy, with RELAP outputting higher temperatures. These results provide some evidence that RELAP can be used with confidence in modeling transients for IVG.« less

MOX fuel assembly design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reese, A.P.; Crowther, R.L. Jr.

1992-02-18

This patent describes improvement in a boiling water reactor core having a plurality of vertically upstanding fuel bundles; each fuel bundle containing longitudinally extending sealed rods with fissile material therein; the improvement comprises the fissile material including a mixture of uranium and recovered plutonium in rods of the fuel bundle at locations other than the corners of the fuel bundle; and, neutron absorbing material being located in rods of the fuel bundle at rod locations adjacent the corners of the fuel bundles whereby the neutron absorbing material has decreased shielding from the plutonium and maximum exposure to thermal neutrons formore » shaping the cold reactivity shutdown zone in the fuel bundle.« less

Three-dimensional reconstruction from multiple reflected views within a realist painting: an application to Scott Fraser's "Three way vanitas"

NASA Astrophysics Data System (ADS)

Smith, Brandon M.; Stork, David G.; Zhang, Li

2009-01-01

The problem of reconstructing a three-dimensional scene from single or multiple views has been thoroughly studied in the computer vision literature, and recently has been applied to problems in the history of art. Criminisi pioneered the application of single-view metrology to reconstructing the fictive spaces in Renaissance paintings, such as the vault in Masaccio's Trinità and the plaza in Piero della Francesca's Flagellazione. While the vast majority of realist paintings provide but a single view, some provide multiple views, through mirrors depicted within their tableaus. The contemporary American realist Scott Fraser's Three way vanitas is a highly realistic still-life containing three mirrors; each mirror provides a new view of the objects in the tableau. We applied multiple-view reconstruction methods to the direct image and the images reflected by these mirrors to reconstruct the three-dimensional tableau. Our methods estimate virtual viewpoints for each view using the geometric constraints provided by the direct view of the mirror frames, along with the reflected images themselves. Moreover, our methods automatically discover inconsistencies between the different views, including ones that might elude careful scrutiny by eye, for example the fact that the height of the water in the glass differs between the direct view and that in the mirror at the right. We believe our work provides the first application of multiple-view reconstruction to a single painting and will have application to other paintings and questions in the history of art.

Realtime Reconstruction of an Animating Human Body from a Single Depth Camera.

PubMed

Chen, Yin; Cheng, Zhi-Quan; Lai, Chao; Martin, Ralph R; Dang, Gang

2016-08-01

We present a method for realtime reconstruction of an animating human body,which produces a sequence of deforming meshes representing a given performance captured by a single commodity depth camera. We achieve realtime single-view mesh completion by enhancing the parameterized SCAPE model.Our method, which we call Realtime SCAPE, performs full-body reconstruction without the use of markers.In Realtime SCAPE, estimations of body shape parameters and pose parameters, needed for reconstruction, are decoupled. Intrinsic body shape is first precomputed for a given subject, by determining shape parameters with the aid of a body shape database. Subsequently, per-frame pose parameter estimation is performed by means of linear blending skinning (LBS); the problem is decomposed into separately finding skinning weights and transformations. The skinning weights are also determined offline from the body shape database,reducing online reconstruction to simply finding the transformations in LBS. Doing so is formulated as a linear variational problem;carefully designed constraints are used to impose temporal coherence and alleviate artifacts. Experiments demonstrate that our method can produce full-body mesh sequences with high fidelity.

Polycation induced actin bundles.

PubMed

Muhlrad, Andras; Grintsevich, Elena E; Reisler, Emil

2011-04-01

Three polycations, polylysine, the polyamine spermine and the polycationic protein lysozyme were used to study the formation, structure, ionic strength sensitivity and dissociation of polycation-induced actin bundles. Bundles form fast, simultaneously with the polymerization of MgATP-G-actins, upon the addition of polycations to solutions of actins at low ionic strength conditions. This indicates that nuclei and/or nascent filaments bundle due to attractive, electrostatic effect of polycations and the neutralization of repulsive interactions of negative charges on actin. The attractive forces between the filaments are strong, as shown by the low (in nanomolar range) critical concentration of their bundling at low ionic strength. These bundles are sensitive to ionic strength and disassemble partially in 100 mM NaCl, but both the dissociation and ionic strength sensitivity can be countered by higher polycation concentrations. Cys374 residues of actin monomers residing on neighboring filaments in the bundles can be cross-linked by the short span (5.4Å) MTS-1 (1,1-methanedyl bismethanethiosulfonate) cross-linker, which indicates a tight packing of filaments in the bundles. The interfilament cross-links, which connect monomers located on oppositely oriented filaments, prevent disassembly of bundles at high ionic strength. Cofilin and the polysaccharide polyanion heparin disassemble lysozyme induced actin bundles more effectively than the polylysine-induced bundles. The actin-lysozyme bundles are pathologically significant as both proteins are found in the pulmonary airways of cystic fibrosis patients. Their bundles contribute to the formation of viscous mucus, which is the main cause of breathing difficulties and eventual death in this disorder. Copyright © 2011 Elsevier B.V. All rights reserved.

Single reconstructed Fermi surface pocket in an underdoped single-layer cuprate superconductor

DOE PAGES

Chan, Mun Keat; Harrison, Neil; Mcdonald, Ross David; ...

2016-07-22

The observation of a reconstructed Fermi surface via quantum oscillations in hole-doped cuprates opened a path towards identifying broken symmetry states in the pseudogap regime. However, such an identification has remained inconclusive due to the multi-frequency quantum oscillation spectra and complications accounting for bilayer effects in most studies. We overcome these impediments with high-resolution measurements on the structurally simpler cuprate HgBa2CuO4+δ (Hg1201), which features one CuO2 plane per primitive unit cell. We find only a single oscillatory component with no signatures of magnetic breakdown tunnelling to additional orbits. Therefore, the Fermi surface comprises a single quasi-two-dimensional pocket. Quantitative modelling ofmore » these results indicates that a biaxial charge density wave within each CuO2 plane is responsible for the reconstruction and rules out criss-crossed charge stripes between layers as a viable alternative in Hg1201. Lastly, we determine that the characteristic gap between reconstructed pockets is a significant fraction of the pseudogap energy« less

Nonabelian Bundle Gerbes, Their Differential Geometry and Gauge Theory

NASA Astrophysics Data System (ADS)

Aschieri, Paolo; Cantini, Luigi; Jurčo, Branislav

2005-03-01

Bundle gerbes are a higher version of line bundles, we present nonabelian bundle gerbes as a higher version of principal bundles. Connection, curving, curvature and gauge transformations are studied both in a global coordinate independent formalism and in local coordinates. These are the gauge fields needed for the construction of Yang-Mills theories with 2-form gauge potential.

Bundled payment fails to gain a foothold In California: the experience of the IHA bundled payment demonstration.

PubMed

Ridgely, M Susan; de Vries, David; Bozic, Kevin J; Hussey, Peter S

2014-08-01

To determine whether bundled payment could be an effective payment model for California, the Integrated Healthcare Association convened a group of stakeholders (health plans, hospitals, ambulatory surgery centers, physician organizations, and vendors) to develop, through a consensus process, the methods and means of implementing bundled payment. In spite of a high level of enthusiasm and effort, the pilot did not succeed in its goal to implement bundled payment for orthopedic procedures across multiple payers and hospital-physician partners. An evaluation of the pilot documented a number of barriers, such as administrative burden, state regulatory uncertainty, and disagreements about bundle definition and assumption of risk. Ultimately, few contracts were signed, which resulted in insufficient volume to test hypotheses about the impact of bundled payment on quality and costs. Although bundled payment failed to gain a foothold in California, the evaluation provides lessons for future bundled payment initiatives. Project HOPE—The People-to-People Health Foundation, Inc.

Single-stage soft tissue reconstruction and orbital fracture repair for complex facial injuries.

PubMed

Wu, Peng Sen; Matoo, Reshvin; Sun, Hong; Song, Li Yuan; Kikkawa, Don O; Lu, Wei

2017-02-01

Orbital fractures with open periorbital wounds cause significant morbidity. Timing of debridement with fracture repair and soft tissue reconstruction is controversial. This study focuses on the efficacy of early single-stage repair in combined bony and soft tissue injuries. Retrospective review. Twenty-three patients with combined open soft tissue wounds and orbital fractures were studied for single-stage orbital reconstruction and periorbital soft tissue repair. Inclusion criteria were open soft tissue wounds with clinical and radiographic evidence of orbital fractures and repair performed within 48 h after injury. Surgical complications and reconstructive outcomes were assessed over 6 months. The main outcome measures were enophthalmos, pre- and post-CT imaging of orbits, scar evaluation, presence of diplopia, and eyelid position. Enophthalmos was corrected in 16/19 cases and improved in 3/19 cases. 3D reconstruction of CT images showed markedly improved orbital alignment with objective measurements of the optic foramen to cornea distance (mm) in reconstructed orbits relative to intact orbits of 0.66, 95% confidence interval [CI] (lower 0.33, upper 0.99) mm. The mean baseline of Stony Brook Scar Evaluation Scale was 0.6, 95%CI (0.30-0.92), and for 6 months, the mean score was 3.4, 95%CI (3.05-3.73). Residual diplopia in secondary gazes was present in two patients; one patient had ectropion. Complications included one case of local wound infection. An early single-stage repair of combined soft tissue and orbital fractures yields satisfactory functional and aesthetic outcomes. Complications are low and likely related to trauma severity. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Single stage treatment of ankylosis of the temporomandibular joint using patient-specific total joint replacement and virtual surgical planning.

PubMed

Haq, Jahrad; Patel, Nishma; Weimer, Katherine; Matthews, N Shaun

2014-04-01

Ankylosis of the temporomandibular joint (TMJ) is a debilitating condition that can result in pain, trismus, and a poor quality of life. It can be caused by injury, infection, and rheumatoid disease. Current management includes gap arthroplasty, interpositional arthroplasty, and reconstruction. Traditionally, joints are reconstructed using stock implants, or the procedure is done in two stages with an additional computed tomography (CT) scan between the resective and reconstructive procedures and use of stereolithographic models to aid the design of the definitive prostheses. We describe a technique for the resection of ankylosis and reconstruction of the joint in a single operation using virtually designed custom-made implants. Five patients with ankylosis of the TMJ had a single stage operation with reconstruction between 2010 and 2012. All had preoperative high-resolution CT with contrast angiography. During an international web-based teleconference between the surgeon and the engineer a virtual resection of the ankylosis was done using the reconstructed CT images. The bespoke cutting guides and implants were designed virtually at the same time and were then manufactured precisely using computer-aided design and manufacture (CAD-CAM) over 6 weeks. After release of the ankylosis and reconstruction, the patients underwent an exercise regimen to improve mouth opening. Follow-up was for a minimum of 6 months. Four patients had one operation, and one patient had two. Median/Mean maximum incisal opening increased from 0.6mm before operation to 25 mm afterwards (range 23-27), and there was minimal surgical morbidity. This new method effectively treats ankylosis of the TMJ in a single stage procedure. Fewer operations and hospital stays, and the maintenance of overall clinical outcome are obvious advantages. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Modelling the development and arrangement of the primary vascular structure in plants.

PubMed

Cartenì, Fabrizio; Giannino, Francesco; Schweingruber, Fritz Hans; Mazzoleni, Stefano

2014-09-01

The process of vascular development in plants results in the formation of a specific array of bundles that run throughout the plant in a characteristic spatial arrangement. Although much is known about the genes involved in the specification of procambium, phloem and xylem, the dynamic processes and interactions that define the development of the radial arrangement of such tissues remain elusive. This study presents a spatially explicit reaction-diffusion model defining a set of logical and functional rules to simulate the differentiation of procambium, phloem and xylem and their spatial patterns, starting from a homogeneous group of undifferentiated cells. Simulation results showed that the model is capable of reproducing most vascular patterns observed in plants, from primitive and simple structures made up of a single strand of vascular bundles (protostele), to more complex and evolved structures, with separated vascular bundles arranged in an ordered pattern within the plant section (e.g. eustele). The results presented demonstrate, as a proof of concept, that a common genetic-molecular machinery can be the basis of different spatial patterns of plant vascular development. Moreover, the model has the potential to become a useful tool to test different hypotheses of genetic and molecular interactions involved in the specification of vascular tissues.

Confinement-Dependent Friction in Peptide Bundles

PubMed Central

Erbaş, Aykut; Netz, Roland R.

2013-01-01

Friction within globular proteins or between adhering macromolecules crucially determines the kinetics of protein folding, the formation, and the relaxation of self-assembled molecular systems. One fundamental question is how these friction effects depend on the local environment and in particular on the presence of water. In this model study, we use fully atomistic MD simulations with explicit water to obtain friction forces as a single polyglycine peptide chain is pulled out of a bundle of k adhering parallel polyglycine peptide chains. The whole system is periodically replicated along the peptide axes, so a stationary state at prescribed mean sliding velocity V is achieved. The aggregation number is varied between k = 2 (two peptide chains adhering to each other with plenty of water present at the adhesion sites) and k = 7 (one peptide chain pulled out from a close-packed cylindrical array of six neighboring peptide chains with no water inside the bundle). The friction coefficient per hydrogen bond, extrapolated to the viscous limit of vanishing pulling velocity V → 0, exhibits an increase by five orders of magnitude when going from k = 2 to k = 7. This dramatic confinement-induced friction enhancement we argue to be due to a combination of water depletion and increased hydrogen-bond cooperativity. PMID:23528088

Quantitative Analysis of Statics and Dynamics of Actin Cables in Fission Yeast

NASA Astrophysics Data System (ADS)

Yusuf, Eddy; Wu, Jian-Qiu; Vavylonis, Dimitrios

2010-03-01

The assembly of actin and tubulin proteins into long filaments and bundles, i.e. closely-packed filaments, underlies important cellular processes such as cell motility, intracellular transport, and cell division. Recent theoretical and experimental work has addressed the nonequilibrium dynamics of single microtubules within live cells [1]. Actin filaments usually form dense networks that prevents microscopic imaging of individual filaments or bundles. Here, we studied actin dynamics using fission yeast that has low-density actin cytoskeleton consisting of actin cables (actin bundles aligned along the long axis of the cell) and ``actin patches.'' Yeast cells expressing GFP-CHD were imaged by 3D confocal microscopy. Stretching open active contours [2] were used to segment and track individual actin cables. We analyzed their curvature distribution, the tangent correlation, and the temporal bending amplitude fluctuations. We contrast our findings to equilibrium fluctuating semiflexible polymers and to microtubules in cells. We calculate the important time and length scales for the actin cables. We also discuss our findings within the broad context of understanding actin assembly in cells. [1] C. P. Brangwynne et. al., Phys. Rev. Lett. 100, 118104 (2008) [2] H. Li et. al., Proc. of the IEEE Int'l Symposium on Biomedical Imaging: From Nano to Macro, ISBI'09

Cytoskeletal mechanics: Structure and Dynamics

NASA Astrophysics Data System (ADS)

Bausch, Andreas

2008-03-01

The actin cytoskeleton, a dynamic network of semiflexible filaments and associated regulatory proteins, is responsible for the extraordinary viscoelastic properties of cells. Especially for cellular motility the controlled self assembly to defined structures and the dynamic reorganization on different time scales are of outstanding importance. A prominent example for the controlled self assembly are actin bundles: in many cytoskeletal processes cells rely on the tight control of the structural and mechanical properties of the actin bundles. Using an in vitro model system we show that size control relies on a mismatch between the helical structure of individual actin filaments and the packing symmetry within bundles. While such self assembled structure may evoke the picture of a static network the contrary is the case: the cytoskeleton is highly dynamic and a constant remodeling takes place in vivo. Such dynamic reorganization of the cytoskeleton relies on the non-static nature of single actin/ABP bonds. Here, we study the thermal and forced unbinding events of individual ABP in such in vitro networks. The binding kinetics of the transient crosslinkers determines the mechanical response of such networks -- in the linear as well in the non-linear regime. These effects are important prerequisites for the high adaptability of cells and at the same time might be the molecular mechanism employed by them for mechanosensing.

SubspaceEM: A Fast Maximum-a-posteriori Algorithm for Cryo-EM Single Particle Reconstruction

PubMed Central

Dvornek, Nicha C.; Sigworth, Fred J.; Tagare, Hemant D.

2015-01-01

Single particle reconstruction methods based on the maximum-likelihood principle and the expectation-maximization (E–M) algorithm are popular because of their ability to produce high resolution structures. However, these algorithms are computationally very expensive, requiring a network of computational servers. To overcome this computational bottleneck, we propose a new mathematical framework for accelerating maximum-likelihood reconstructions. The speedup is by orders of magnitude and the proposed algorithm produces similar quality reconstructions compared to the standard maximum-likelihood formulation. Our approach uses subspace approximations of the cryo-electron microscopy (cryo-EM) data and projection images, greatly reducing the number of image transformations and comparisons that are computed. Experiments using simulated and actual cryo-EM data show that speedup in overall execution time compared to traditional maximum-likelihood reconstruction reaches factors of over 300. PMID:25839831

78 FR 76987 - Adjustment of Determination of Compulsory License Rates for Mechanical and Digital Phonorecords

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-20

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