Science.gov

Sample records for facet joint loading

  1. Load Rate of Facet Joints at the Adjacent Segment Increased After Fusion

    PubMed Central

    Li, Hui; Pei, Bao-Qing; Yang, Jin-Cai; Hai, Yong; Li, De-Yu; Wu, Shu-Qin

    2015-01-01

    Background: The cause of the adjacent segment degeneration (ASD) after fusion remains unknown. It is reported that adjacent facet joint stresses increase after anterior cervical discectomy and fusion. This increase of stress rate may lead to tissue injury. Thus far, the load rate of the adjacent segment facet joint after fusion remains unclear. Methods: Six C2–C7 cadaveric spine specimens were loaded under four motion modes: Flexion, extension, rotation, and lateral bending, with a pure moment using a 6° robot arm combined with an optical motion analysis system. The Tecscan pressure test system was used for testing facet joint pressure. Results: The contact mode of the facet joints and distributions of the force center during different motions were recorded. The adjacent segment facet joint forces increased faster after fusion, compared with intact conditions. While the magnitude of pressures increased, there was no difference in distribution modes before and after fusion. No pressures were detected during flexion. The average growth velocity during extension was the fastest and was significantly faster than lateral bending. Conclusions: One of the reasons for cartilage injury was the increasing stress rate of loading. This implies that ASD after fusion may be related to habitual movement before and after fusion. More and faster extension is disadvantageous for the facet joints and should be reduced as much as possible. PMID:25881597

  2. Cervical facet joint kinematics during bilateral facet dislocation

    PubMed Central

    Panjabi, Manohar M.; Simpson, Andrew K.; Pearson, Adam M.; Tominaga, Yasuhiro; Yue, James J.

    2007-01-01

    Previous biomechanical models of cervical bilateral facet dislocation (BFD) are limited to quasi-static loading or manual ligament transection. The goal of the present study was to determine the facet joint kinematics during high-speed BFD. Dislocation was simulated using ten cervical functional spinal units with muscle force replication by frontal impact of the lower vertebra, tilted posteriorly by 42.5°. Average peak rotations and anterior sliding (displacement of upper articulating facet surface along the lower), separation and compression (displacement of upper facet away from and towards the lower), and lateral shear were determined at the anterior and posterior edges of the right and left facets and statistically compared (P < 0.05). First, peak facet separation occurred, and was significantly greater at the left posterior facet edge, as compared to the anterior edges. Next, peak flexion rotation and anterior facet sliding occurred, followed by peak facet compression. The highest average facet translation peaks were 22.0 mm for anterior sliding, 7.9 mm for separation, 9.9 mm for compression and 3.6 mm for lateral shear. The highest average rotation of 63° occurred in flexion, significantly greater than all other directions. These events occurred, on average, within 0.29 s following impact. During BFD, the main sagittal motions included facet separation, flexion rotation, anterior sliding, followed by compression, however, non-sagittal motions also existed. These motions indicated that unilateral dislocation may precede bilateral dislocation. PMID:17566792

  3. Types of subtalar joint facets.

    PubMed

    Jung, Min-Ho; Choi, Byoung Young; Lee, Ji Yong; Han, Chang Sung; Lee, Jin Suk; Yang, Young Chul; Cho, Byung Pil

    2015-08-01

    Articular facets of the clinical subtalar joint (CSTJ) were analyzed using a total of 118 (right 57, left 61) dry, paired calcanei and tali from 68 Korean adult cadavers. The CSTJ facets were classified into the following three types depending on their continuity: type A, all three facets are separated; type B, the anterior and middle facets are partially connected; and type C, the anterior and middle facets are fused to form a single facet. The continuity between the anterior and middle facets was represented by the degree of separation (DS), which ranged between 2.00 (type A) and 1.00 (type C). Type A was most common (39.0 %) in calcanei and rarest (11.0 %) in tali. Matching of calcaneus-talus pairs yielded five combined types: A-A (11.0 %), A-B (28.0 %), B-B (18.6 %), B-C (13.6 %), and C-C (28.8 %). The mean DS was slightly greater in calcanei (1.53) than in tali (1.32), and decreased in the order of types A-A, A-B, B-B, B-C, and C-C. The intersecting angles between the anterior and middle facets, which are related to the mobility of the CSTJ, were inversely related to the DS. These findings indicate that the anterior and middle facets are fused more frequently in tali than in calcanei, and combinations of different CSTJ facet types (A-B, B-C) exist over 40 % of feet. Our results indicate that types with a smaller DS (such as B-C and C-C) are relatively mobile but less stable compared to those with a greater DS (such as A-A and A-B). PMID:25822134

  4. Management of lumbar zygapophysial (facet) joint pain

    PubMed Central

    Manchikanti, Laxmaiah; Hirsch, Joshua A; Falco, Frank JE; Boswell, Mark V

    2016-01-01

    AIM: To investigate the diagnostic validity and therapeutic value of lumbar facet joint interventions in managing chronic low back pain. METHODS: The review process applied systematic evidence-based assessment methodology of controlled trials of diagnostic validity and randomized controlled trials of therapeutic efficacy. Inclusion criteria encompassed all facet joint interventions performed in a controlled fashion. The pain relief of greater than 50% was the outcome measure for diagnostic accuracy assessment of the controlled studies with ability to perform previously painful movements, whereas, for randomized controlled therapeutic efficacy studies, the primary outcome was significant pain relief and the secondary outcome was a positive change in functional status. For the inclusion of the diagnostic controlled studies, all studies must have utilized either placebo controlled facet joint blocks or comparative local anesthetic blocks. In assessing therapeutic interventions, short-term and long-term reliefs were defined as either up to 6 mo or greater than 6 mo of relief. The literature search was extensive utilizing various types of electronic search media including PubMed from 1966 onwards, Cochrane library, National Guideline Clearinghouse, clinicaltrials.gov, along with other sources including previous systematic reviews, non-indexed journals, and abstracts until March 2015. Each manuscript included in the assessment was assessed for methodologic quality or risk of bias assessment utilizing the Quality Appraisal of Reliability Studies checklist for diagnostic interventions, and Cochrane review criteria and the Interventional Pain Management Techniques - Quality Appraisal of Reliability and Risk of Bias Assessment tool for therapeutic interventions. Evidence based on the review of the systematic assessment of controlled studies was graded utilizing a modified schema of qualitative evidence with best evidence synthesis, variable from level I to level V

  5. In Vivo Measurement of the Subchondral Bone Thickness of Lumbar Facet Joint Using Magnetic Resonance Imaging

    PubMed Central

    Duan, C. Y.; Espinoza Orías, A. A.; Shott, S.; An, H. S.; Andersson, G.B.J.; Hu, J.Z.; Lu, H. B.; Inoue, N.

    2010-01-01

    Summary Objective To measure in vivo thicknesses of the facet joint subchondral bone across genders, age groups, with or without low back pain symptom groups and spinal levels. Methods Lumbar (L1–L2 to L5-S1) magnetic resonance (MR) imaging was performed in 81 subjects (41 males and 40 females, mean age 37.6 years). Thicknesses of the subchondral bone were measured in 1,620 facet joints using the MR images with custom-written image processing algorithms together with a multi-threshold segmentation technique using each facet joint’s middle axial-slice. This method was validated with 12 cadaver facet joints, scanned with both MR and micro-computed tomography images. Results An overall average thickness value for the 1,620 analyzed joints was measured as 1.56 ± 0.01 mm. The subchondral bone thickness values showed significant increases with successive lower spinal levels in the subjects without low back pain. The facet joint subchondral bone thickness in asymptomatic females was much smaller than in asymptomatic males. Mean subchondral bone thickness in the superior facet was greater than that in the inferior facet in both female and male asymptomatic subjects. Conclusions This study is the first to quantitatively show subchondral bone thickness using a validated MR-based technique. The subchondral bone thickness was greater in asymptomatic males and increased with each successive lower spinal level. These findings may suggest that the subchondral bone thickness increases with loading. Furthermore, the superior facet subchondral bone was thicker than the inferior facet in all cases regardless of gender, age or spinal level in the subjects without low back pain. More research is needed to link subchondral bone microstructure to facet joint kinematics and spinal loads. PMID:21034837

  6. Cervical zygapophysial (facet) joint pain: effectiveness of interventional management strategies.

    PubMed

    Manchikanti, Laxmaiah; Hirsch, Joshua A; Kaye, Alan D; Boswell, Mark V

    2016-01-01

    Diagnostic facet joint nerve blocks have been utilized in the diagnosis of cervical facet joint pain in patients without disk herniation or radicular pain due to a lack of reliable noninvasive diagnostic measures. Therapeutic interventions include intra-articular injections, facet joint nerve blocks and radiofrequency neurotomy. The diagnostic accuracy and effectiveness of facet joint interventions have been assessed in multiple diagnostic accuracy studies, randomized controlled trials (RCTs), and systematic reviews in managing chronic neck pain. This assessment shows there is Level II evidence based on a total of 11 controlled diagnostic accuracy studies for diagnosing cervical facet joint pain in patients without disk herniation or radicular pain utilizing controlled diagnostic blocks. Due to significant variability and internal inconsistency regarding prevalence in a heterogenous population; despite 11 studies, evidence is determined as Level II. Prevalence ranged from 36% to 67% with at least 80% pain relief as the criterion standard with a false-positive rate ranging from 27% to 63%. The evidence is Level II for the long-term effectiveness of radiofrequency neurotomy and facet joint nerve blocks in managing cervical facet joint pain. There is Level III evidence for cervical intra-articular injections. PMID:26653406

  7. Facet joint changes after application of lumbar nonfusion dynamic stabilization.

    PubMed

    Lee, Soo Eon; Jahng, Tae-Ahn; Kim, Hyun Jib

    2016-01-01

    OBJECTIVE The long-term effects on adjacent-segment pathology after nonfusion dynamic stabilization is unclear, and, in particular, changes at the adjacent facet joints have not been reported in a clinical study. This study aims to compare changes in the adjacent facet joints after lumbar spinal surgery. METHODS Patients who underwent monosegmental surgery at L4-5 with nonfusion dynamic stabilization using the Dynesys system (Dynesys group) or transforaminal lumbar interbody fusion with pedicle screw fixation (fusion group) were retrospectively compared. Facet joint degeneration was evaluated at each segment using the CT grading system. RESULTS The Dynesys group included 15 patients, while the fusion group included 22 patients. The preoperative facet joint degeneration CT grades were not different between the 2 groups. Compared with the preoperative CT grades, 1 side of the facet joints at L3-4 and L4-5 had significantly more degeneration in the Dynesys group. In the fusion group, significant facet joint degeneration developed on both sides at L2-3, L3-4, and L5-S1. The subjective back and leg pain scores were not different between the 2 groups during follow-up, but functional outcome based on the Oswestry Disability Index improved less in the fusion group than in the Dynesys group. CONCLUSIONS Nonfusion dynamic stabilization using the Dynesys system had a greater preventative effect on facet joint degeneration in comparison with that obtained using fusion surgery. The Dynesys system, however, resulted in facet joint degeneration at the instrumented segments and above. An improved physiological nonfusion dynamic stabilization system for lumbar spinal surgery should be developed. PMID:26721580

  8. Lumbar Facet Joint Motion in Patients with Degenerative Spondylolisthesis

    PubMed Central

    Yao, Qi; Wang, Shaobai; Shin, Jae-Hyuk; Li, Guoan; Wood, Kirkham B.

    2012-01-01

    Study Design Controlled laboratory study. Objective To investigate the in vivo biomechanical effect of degenerative lumbar spondylolisthesis (DLS) on the motion of the facet joint during various functional weight-bearing activities. Summary of Background Data Although the morphological changes of the facet joints in patients with DLS have been reported in a few studies, no data has been reported on the kinematics of these facet joints. Methods Ten patients with DLS at L4–L5 were studied. Each patient underwent a magnetic resonance imaging (MRI) scan to obtain three-dimensional (3D) models of the lumbar vertebrae from L2–L5 as well as a dual fluoroscopic imaging scan in different postures: flexion-extension, left-right bending and left-right torsion. The positions of the vertebrae were reproduced by matching the MRI-based vertebral models to the fluoroscopic images. The kinematics of the facet joint and the ranges of motion (ROMs) were compared with those of healthy subjects and those of patients with degenerative disc diseases (DDD) previously published. Results In DLS patients, the range of rotation of the facet joints was significantly less at the DLS level (L4–L5) than that at the adjacent levels (L2–L3 and L3–L4), while the range of translation was similar at all levels. The range of rotation at the facet joints of the DLS level decreased compared to those of both the DDD patients and healthy subjects at the corresponding vertebral level (L4–L5), while no significant difference was found in the range of translation. The ROM of facet joints in DLS and in DDD patients was similar at the adjacent levels (L2–L3 and L3–L4). Conclusion The range of rotation decreased at the facet joints at the DLS level (L4–L5) in patients compared to those in healthy subjects and DDD patients. This decrease in range of rotation implies that the DLS disease may cause restabilization of the joint. The data may help the selection of conservative treatment or different

  9. Epiduroscopic Removal of a Lumbar Facet Joint Cyst

    PubMed Central

    Jin, Hyun Seung; Bae, Jun Yeol; In, Chi Bum; Choi, Eun Joo; Lee, Pyung Bok

    2015-01-01

    Facet joint synovial cysts are usually associated with osteoarthritis of the adjacent facet joint and/or spondylolisthesis. In between the conservative and operative ends of the treatment spectrum lie minimally invasive techniques such as cyst rupture using epiduroscopy. In this report, we describe an 82-year-old male patient presenting with low back pain radiating to his lower left extremity and associated paresthesia. Magnetic resonance imaging of the lumbar spine revealed a synovial cyst at left L4/5 facet joint. Using epiduroscopy, the cyst was mechanically ruptured by popping it with the tip of the scope. The patient remained symptom-free at his successive visits until 12 months after the procedure, and was opened for desired follow up. PMID:26495082

  10. Three-dimensional evaluation of the facet joints

    NASA Astrophysics Data System (ADS)

    Folio, Les R.

    1990-04-01

    Computerized tomography and magnetic resonance imaging nave revolurionalized analysis of vertebral anatomy and pathology. Further advances with 3-dimensional imaging have recently become an important adjunct for diagnosis and treatment in structural abnormalities. Facets are intimately related to their surrounding musculature and malalignment may cause pain directly or indirectly. High resolution 3-dimensional reformations of CT Scans give us new insight on structure and function of facet joints, since their motion and architecture are ever complex. It is well documented in the literature that facet joint biomecnanics is a partial contributor to the myriad at causes of low back The term "facet Joint syndrome" was coined in 1933 by GhorMley.3 The osteopathic lesion complex is well defined by LeRoy and McCole and comparison of roentgenographic findings before and after manipulation has teen described by Long and Lioyd.4,5 since alterations in facet biamechanics are an important aspect of osteopathic manipulative therapy (OT), 3-dimensional hign resolution imaging will prove to be a great asset in osteopathic research. Rotating the spine allows for different viewing perspectives to provide optimal and consistent measurements of the facet joint. Rotations are performed on the X, Y and 7, axis and measurements pre and post-manipulation are performed and compared on matching axis and perspectives. Rotation about the X, Y and Z axis help appreciate the 3-dimensionality of the vertebral column to project to the viewer a feeling that the spine is floating in space before them. This does give the viewer a 3-D understanding of the object however, only at a perspective at a Lime.

  11. Augmented reality needle guidance improves facet joint injection training

    NASA Astrophysics Data System (ADS)

    Ungi, Tamas; Yeo, Caitlin T.; U-Thainual, Paweena; McGraw, Robert C.; Fichtinger, Gabor

    2011-03-01

    PURPOSE: The purpose of this study was to determine if medical trainees would benefit from augmented reality image overlay and laser guidance in learning how to set the correct orientation of a needle for percutaneous facet joint injection. METHODS: A total of 28 medical students were randomized into two groups: (1) The Overlay group received a training session of four insertions with image and laser guidance followed by two insertions with laser overlay only; (2) The Control group was trained by carrying out six freehand insertions. After the training session, needle trajectories of two facet joint injections without any guidance were recorded by an electromagnetic tracker and were analyzed. Number of successful needle placements, distance covered by needle tip inside the phantom and procedural time were measured to evaluate performance. RESULTS: Number of successful placements was significantly higher in the Overlay group compared to the Control group (85.7% vs. 57.1%, p = 0.038). Procedure time and distance covered inside phantom have both been found to be less in the Overlay group, although not significantly. CONCLUSION: Training with augmented reality image overlay and laser guidance improves the accuracy of facet joint injections in medical students learning image-guided facet joint needle placement.

  12. 12. Pain originating from the lumbar facet joints.

    PubMed

    van Kleef, Maarten; Vanelderen, Pascal; Cohen, Steven P; Lataster, Arno; Van Zundert, Jan; Mekhail, Nagy

    2010-01-01

    Although the existence of a "facet syndrome" had long been questioned, it is now generally accepted as a clinical entity. Depending on the diagnostic criteria, the zygapophysial joints account for between 5% and 15% of cases of chronic, axial low back pain. Most commonly, facetogenic pain is the result of repetitive stress and/or cumulative low-level trauma, leading to inflammation and stretching of the joint capsule. The most frequent complaint is axial low back pain with referred pain perceived in the flank, hip, and thigh. No physical examination findings are pathognomonic for diagnosis. The strongest indicator for lumbar facet pain is pain reduction after anesthetic blocks of the rami mediales (medial branches) of the rami dorsales that innervate the facet joints. Because false-positive and, possibly, false-negative results may occur, results must be interpreted carefully. In patients with injection-confirmed zygapophysial joint pain, procedural interventions can be undertaken in the context of a multidisciplinary, multimodal treatment regimen that includes pharmacotherapy, physical therapy and regular exercise, and, if indicated, psychotherapy. Currently, the "gold standard" for treating facetogenic pain is radiofrequency treatment (1 B+). The evidence supporting intra-articular corticosteroids is limited; hence, this should be reserved for those individuals who do not respond to radiofrequency treatment (2 B±). PMID:20667027

  13. Material Properties of the Human Lumbar Facet Joint Capsule

    PubMed Central

    Little, Jesse S.; Khalsa, Partap S.

    2005-01-01

    The human facet joint capsule is one of the structures in the lumbar spine that constrains motions of vertebrae during global spine loading (e.g., physiological flexion). Computational models of the spine have not been able to include accurate nonlinear and viscoelastic material properties, as they have not previously been measured. Capsules were tested using a uniaxial ramp-hold protocol or a haversine displacement protocol using a commercially available materials testing device. Plane strain was measured optically. Capsules were tested both parallel and perpendicular to the dominant orientation of the collagen fibers in the capsules. Viscoelastic material properties were determined. Parallel to the dominant orientation of the collagen fibers, the complex modulus of elasticity was E* = 1.63MPa, with a storage modulus of E′ = 1.25MPa and a loss modulus of: E″ = 0.39MPa. The mean stress relaxation rates for static and dynamic loading were best fit with first-order polynomials: B (ɛ) = 0.1110 ɛ − 0.0733 and B (ɛ) = −0.1249ɛ 11794-8181 +0.0190, respectively. Perpendicular to the collagen fiber orientation, the viscous and elastic secant moduli were 1.81 and 1.00 MPa, respectively. The mean stress relaxation rate for static loading was best fit with a first-order polynomial: B (ɛ) = − 0.04ɛ − 0.06. Capsule strength parallel and perpendicular to collagen fiber orientation was 1.90 and 0.95 MPa, respectively, and extensibility was 0.65 and 0.60, respectively. Poisson’s ratio parallel and perpendicular to fiber orientation was 0.299 and 0.488, respectively. The elasticity moduli were nonlinear and anisotropic, and capsule strength was larger aligned parallel to the collagen fibers. The phase lag between stress and strain increased with haversine frequency, but the storage modulus remained large relative to the complex modulus. The stress relaxation rate was strain dependent parallel to the collagen fibers, but was strain independent perpendicularly

  14. Facet joint laser radiation: tissue effects of a new clinical laser application

    NASA Astrophysics Data System (ADS)

    Werkmann, Klaus; Thal, Dietmar R.

    1996-01-01

    Chronic unilateral and bilateral back pain with pseudoradicular symptoms, is a common clinical syndrome, which in many cases can be related to the facet joint syndrome. The pain is caused by mechanical affection of synovial and capsular nerve terminals. Therefore, current therapeutical attempts including physical therapy, intra-articular injection of local anesthetics and steroids and thermocoagulation of the facet joint with a thermocoagulator, are performed. We confirmed laser coagulation of the facet joint. Porcine cadaveric spines were treated immediately after death by intra-articular facet joint laser radiation. With the pulsed Nd:YAG laser (1064 nm) altogether 600 J were applied in three different places 4 mm apart at the top of the facet joint. The results showed that facet joint laser radiation leads to a small (about 1 - 2 mm diameter) lesion restricted to the facet joint cavity and its synovia. Histologically, we found a central carbonization zone and necrosis, including almost the whole cartilage and approximately 0.2 mm of the adjacent bone. These changes are similar to Nd:Yag-laser applications in other skeletal regions. It is suggested that these changes may lead to facet joint denervation by coagulation of the synovial nerve terminals. Cicatration of the laser lesion might cause ankylosis of this joint. In sum, facet joint laser radiation could be an alternative therapeutical tool for lower back pain of the facet joint syndrome type. Therefore, future clinical application of this technique seems to be very promising.

  15. Factors affecting results of fluoroscopy-guided facet joint injection: Probable differences in the outcome of treatment between pure facet joint hypertrophy and concomitant diseases

    PubMed Central

    Albayrak, Akif; Ozkul, Baris; Balioglu, Mehmet Bulent; Atici, Yunus; Gultekin, Muhammet Zeki; Albayrak, Merih Dilan

    2016-01-01

    Study Design: Retrospective cohort study. Purpose: Facet joints are considered a common source of chronic low-back pain. To determine whether pathogens related to the facet joint arthritis have any effect on treatment failure. Materials and Methods: Facet joint injection was applied to 94 patients treated at our hospital between 2011 and 2012 (mean age 59.5 years; 80 women and 14 men). For the purpose of analysis, the patients were divided into two groups. Patients who only had facet hypertrophy were placed in group A (47 patients, 41 women and 6 men, mean age 55.3 years) and patients who had any additional major pathology to facet hypertrophy were placed in group B (47 patients, 39 women and 8 men, mean age 58.9 years). Injections were applied around the facet joint under surgical conditions utilizing fluoroscopy device guidance. A mixture of methylprednisolone and lidocaine was used as the injection ingredient. Results: In terms of Oswestry Disability Index (ODI) and visual analog scale (VAS) scores, no significant difference was found between preinjection and immediate postinjection values in both groups, and the scores of group A patients were significantly lower (P < 0.005) compared with that of group B patients at the end of the third, sixth, and twelfth month. Conclusion: For low-back pain caused by facet hypertrophy, steroid injection around the facet joint is an effective treatment, but if there is an existing major pathology, it is not as effective. PMID:27041884

  16. Association between facet joint osteoarthritis and the Oswestry Disability Index

    PubMed Central

    Maataoui, Adel; Vogl, Thomas J; Middendorp, Marcus; Kafchitsas, Konstantinos; Khan, M Fawad

    2014-01-01

    AIM: To investigate the correlation of facet joint osteoarthritis (FJOA) at lumbar levels L4/L5 and L5/S1 and the Oswestry Disability Index (ODI). METHODS: The study involved lumbar MRIs of 591 patients with a mean age of 47.3 years. The MRIs of the lumbar spine were performed on a 1.5 Tesla scanner (Magnetom® Avanto, Siemens AG, Erlangen, Germany) using a dedicated receive only spine coil. After initial blinding, each dataset was evaluated by 2 board certified radiologist with more than 5 years experience in musculoskeletal imaging. In total 2364 facet joints were graded. Degenerative changes of the facet joints were evaluated according to the 4-point scale as proposed by Weishaupt et al Functional status was assessed using the ODI. The index is scored from 0 to 100 and interpreted as follows: 0%-20%, minimal disability; 20%-40%, moderate disability; 40%-60%, severe disability; 60%-80%, crippled; 80%-100%, patients are bedbound. Spearman’s coefficient of rank correlation was used for statistical analysis, with significance set at P < 0.05. RESULTS: In total 2364 facet joints at lumbar levels L4/5 and L5/S1 were analysed in 591 individuals. FJOA was present in 97% (L4/L5) and 98% (L5/S1). At level L4/5 (left/right) 17/15 (2.9%/2.5%) were described as grade 0, 146/147 (24.7%/24.9%) as grade 1, 290/302 (49.1%/51.1%) as grade 2 and 138/127 (23.4%/21.5%) as grade 3. At level L5/S1 (left/right) 10/11 (1.7%/1.9%) were described as grade 0, 136/136 (23.0%/23.0%) as grade 1, 318/325 (53.8%/55.0%) as grade 2 and 127/119 (21.5%/20.1%) as grade 3. Regarding the ODI scores, patients’ disability had a minimum of 0% and a maximum of 91.11% with an arithmetic mean of 32.77% ± 17.02%. The majority of patients (48.39%) had moderate functional disability (21%-40%). There was no significant correlation between FJOA and ODI on both sides of lumbar level L4/5 and on the left side of lumbar level L5/S1. A weak positive correlation was evaluated between ODI and FJOA on the right

  17. Subdural empyema following lumbar facet joint injection: An exceeding rare complication.

    PubMed

    Fayeye, Oluwafikayo; Silva, Adikarige Haritha Dulanka; Chavda, Swarupsinh; Furtado, Navin Raoul

    2016-01-01

    Chronic low back pain is extremely common with a life time prevalence estimated at greater than 70% [1]. Facet joint arthrosis is thought to be the causative aetiological substrate in approximately 25% of chronic low back pain cases [2]. Facet joint injection is a routine intervention in the armamentarium for both the diagnostic and therapeutic management of chronic low back pain. In fact, a study by Carrino et al. reported in excess of 94,000 facet joint injection procedures were carried out in the US in 1999 [3]. Although generally considered safe, the procedure is not entirely without risk. Complications including bleeding, infection, exacerbation of pain, dural puncture headache, and pneumothorax have been described. We report a rare case of a 47-year-old female patient who developed a left L4/5 facet septic arthrosis with an associated subdural empyema and meningitis following facet joint injection. This case is unique, as to the best of our knowledge no other case of subdural empyema following facet joint injection has been reported in the literature. Furthermore this case serves to highlight the potential serious adverse sequelae of a routine and apparently innocuous intervention. The need for medical practitioners to be alert to and respond rapidly to the infective complications of facet joint injection cannot be understated. PMID:27154449

  18. Encapsulated Ruffini-like endings in human lumbar facet joints

    PubMed Central

    VANDENABEELE, F.; CREEMERS, J.; LAMBRICHTS, I.; LIPPENS, P.; JANS, M.

    1997-01-01

    The innervation of the human lumbar facet joint capsule was studied by light and electron microscopy. Small numbers of encapsulated corpuscular endings were identified in the dense fibrous layer. Clusters of 2 types of endings were found: small cylindrical corpuscles (type 1) and large fusiform corpuscles (type 2). The corpuscles were classified structurally as Ruffini-type endings. The 1st type was predominant and characterised by a compartmentalised receptor complex, a thin perineurial capsule and a narrow subcapsular space. The 2nd type was characterised by a thicker perineurial capsule, a ‘spindle-like’ receptive complex, and an extensive subcapsular space with capillaries and concentrically oriented fibroblast-like cells. Both types of endings were innervated mainly by thinly myelinated group III (A delta) and unmyelinated group IV (C) nerve fibres that branched and terminated in the receptor complex. Their sensory endings were intimately related to the collagen fibre bundles as multiple enlarged axonal segments (‘beads’) with ultrastructural features which were characteristic of receptive sites: an accumulation of mitochondria and vesicles, and ‘bare’ areas of axolemma lacking a Schwann cell investment but covered by a thin basal lamina. Some beads in the 2nd type of ending contained granular vesicles, 30–60 mm in diameter, resembling sympathetic nerve endings. Small diameter collagen fibrils situated within multilayered basal laminae were found among the multiple receptive sites in the receptive complex in both types of ending. Their possible functional significance in mechanoreception is discussed. Particular attention has been given to their apparent variable orientation to the mechanoreceptive site. PMID:9449076

  19. Comparison of facet joint activity on 99mTc-MDP SPECT/CT with facet joint signal change on MRI with fat suppression

    PubMed Central

    Lehman, Vance T.; Murphy, Robert C.; Schenck, Louis A.; Carter, Rickey E.; Johnson, Geoffrey B.; Kotsenas, Amy L.; Morris, Jonathan M.; Nathan, Mark A.; Wald, John T.; Maus, Timothy P.

    2016-01-01

    PURPOSE We compared signal change on magnetic resonance imaging (MRI) with fat suppression and bone scan activity of lumbar facet joints to determine if these two imaging findings are correlated. METHODS We retrospectively identified all patients who underwent imaging of the lumbar spine for pain evaluation using both technetium-99m methylene disphosphonate single-photon emission computed tomography/computed tomography (99mTc-MDP SPECT/CT) and MRI with at least one fat-suppressed T2- or T1-weighted sequence with gadolinium enhancement within a 180-day interval, at our institution between 1 January 2008 and 19 February 2013. Facet joint activity on 99mTc-MDP SPECT/CT and peri-facet signal change on MRI were rated as normal or increased. Agreement between the two examination types were determined with the κ and prevalence-adjusted bias-adjusted κ (PABAK) statistics. RESULTS This study included 60 patients (28 male, 47%), with a mean age of 49±19.7 years (range, 12–93 years). The κ value indicated no agreement between 99mTc-MDP SPECT/CT and MRI (κ=−0.026; 95% confidence interval: −0.051, 0.000). The PABAK values were fair to high at each spinal level, which suggests that relatively low disease prevalence lowered the κ values. Together, the κ and PABAK values indicate that there is some degree of intermodality agreement, but that it is not consistent. CONCLUSION Overall, facet joint signal change on fat-suppressed MRI did not always correlate with increased 99mTc-MDP SPECT/CT activity. MRI and 99mTc-MDP SPECT/CT for facet joint evaluation should not be considered interchangeable examinations in clinical practice or research. PMID:27035592

  20. 14 CFR 297.4 - Joint loading.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Joint loading. 297.4 Section 297.4... REGULATIONS FOREIGN AIR FREIGHT FORWARDERS AND FOREIGN COOPERATIVE SHIPPERS ASSOCIATIONS General § 297.4 Joint loading. Nothing in this part shall preclude joint loading, meaning the pooling of shipments and...

  1. 14 CFR 296.4 - Joint loading.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Joint loading. 296.4 Section 296.4... REGULATIONS INDIRECT AIR TRANSPORTATION OF PROPERTY General § 296.4 Joint loading. Nothing in this part shall preclude joint loading, meaning the pooling of shipments and their delivery to a direct air carrier...

  2. 14 CFR 297.4 - Joint loading.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Joint loading. 297.4 Section 297.4... REGULATIONS FOREIGN AIR FREIGHT FORWARDERS AND FOREIGN COOPERATIVE SHIPPERS ASSOCIATIONS General § 297.4 Joint loading. Nothing in this part shall preclude joint loading, meaning the pooling of shipments and...

  3. 14 CFR 296.4 - Joint loading.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Joint loading. 296.4 Section 296.4... REGULATIONS INDIRECT AIR TRANSPORTATION OF PROPERTY General § 296.4 Joint loading. Nothing in this part shall preclude joint loading, meaning the pooling of shipments and their delivery to a direct air carrier...

  4. 14 CFR 297.4 - Joint loading.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Joint loading. 297.4 Section 297.4... REGULATIONS FOREIGN AIR FREIGHT FORWARDERS AND FOREIGN COOPERATIVE SHIPPERS ASSOCIATIONS General § 297.4 Joint loading. Nothing in this part shall preclude joint loading, meaning the pooling of shipments and...

  5. 14 CFR 297.4 - Joint loading.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Joint loading. 297.4 Section 297.4... REGULATIONS FOREIGN AIR FREIGHT FORWARDERS AND FOREIGN COOPERATIVE SHIPPERS ASSOCIATIONS General § 297.4 Joint loading. Nothing in this part shall preclude joint loading, meaning the pooling of shipments and...

  6. 14 CFR 296.4 - Joint loading.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Joint loading. 296.4 Section 296.4... REGULATIONS INDIRECT AIR TRANSPORTATION OF PROPERTY General § 296.4 Joint loading. Nothing in this part shall preclude joint loading, meaning the pooling of shipments and their delivery to a direct air carrier...

  7. 14 CFR 297.4 - Joint loading.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Joint loading. 297.4 Section 297.4... REGULATIONS FOREIGN AIR FREIGHT FORWARDERS AND FOREIGN COOPERATIVE SHIPPERS ASSOCIATIONS General § 297.4 Joint loading. Nothing in this part shall preclude joint loading, meaning the pooling of shipments and...

  8. 14 CFR 296.4 - Joint loading.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Joint loading. 296.4 Section 296.4... REGULATIONS INDIRECT AIR TRANSPORTATION OF PROPERTY General § 296.4 Joint loading. Nothing in this part shall preclude joint loading, meaning the pooling of shipments and their delivery to a direct air carrier...

  9. 14 CFR 296.4 - Joint loading.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Joint loading. 296.4 Section 296.4... REGULATIONS INDIRECT AIR TRANSPORTATION OF PROPERTY General § 296.4 Joint loading. Nothing in this part shall preclude joint loading, meaning the pooling of shipments and their delivery to a direct air carrier...

  10. The Effects of Lumbar Facet Dowels on Joint Stiffness: A Biomechanical Study

    PubMed Central

    Trahan, Jayme; Morales, Eric; Richter, Erich O.; Tender, Gabriel C.

    2014-01-01

    Background Facet joint arthrosis may play a significant role in low back pain generation. The placement of facet dowels is a percutaneous treatment that aims to fuse the facets and increase joint stiffness. In this cadaveric study, we evaluated spine stiffness after facet dowel insertion in combination with several surgical procedures and determined which motions promote dowel migration. Methods Six fresh frozen lumbar spines were tested in flexion-extension, lateral bending, and axial rotation. Spine stiffness was determined for the intact specimens, after L4 laminectomy, and after bilateral L4-L5 facet dowel placement, respectively. One specimen underwent a unilateral transforaminal lumbar interbody fusion (TLIF) construct and another underwent extreme lateral interbody fusion (XLIF) graft (22 mm) placement, followed by placement of facet dowels. Afterwards, the specimens were subjected to 10,000 cycles of fatigue testing in flexion-extension or axial rotation. Results The overall decrease in stiffness after laminectomy was 4.6%. Facet dowel placement increased overall stiffness by 7.2%. The greatest increase was seen with axial rotation (13%), compared to flexion, extension, and lateral bending (9.5%, 2.3%, and 5.6%, respectively). The TLIF and XLIF plus dowel construct increased specimen stiffness to 266% and 163% of baseline, respectively. After fatigue testing, dowel migration was detected by computed tomography in the 2 uninstrumented specimens undergoing axial rotation cycling. Conclusion Facet dowels increase the stiffness of the motion segment to which they are applied and can be used in conjunction with laminectomy procedures to increase the stiffness of the joint. However, dowel migration can occur after axial rotation movements. Hybrid TLIF or XLIF plus facet dowel constructs have significantly higher stiffness than noninstrumented ones and may prevent dowel migration. PMID:24688332

  11. A rare case of cervical facet joint and synovial cyst at C5/C6.

    PubMed

    Phan, Kevin; Mobbs, Ralph J

    2016-07-01

    Lumbar synovial cysts are uncommon, and particularly rare at cervical levels. We report a 40-year-old woman who presented with pain distribution in the typical C6 dermatome. MRI revealed a right-sided large extradural cystic lesion adjacent to the C5/C6 facet joint that was hyperintense on T2-weighted MRI and hypointense on T1-weighted MRI. The patient underwent posterior cervical surgery at the C5/C6 level which involved posterior decompressive unilateral laminotomy and excision of the C5/C6 facet joint cyst. Following complete facetectomy of the right C5/C6 facet joint and exposure of the C6 nerve throughout its foraminal course, instrumented fusion was performed. Following the procedure, the patient had an uneventful recovery with relief of her radicular symptoms at follow-up clinical review. PMID:26916905

  12. Radiological and Radionuclide Imaging of Degenerative Disease of the Facet Joints.

    PubMed

    Shur, Natalie; Corrigan, Alexis; Agrawal, Kanhaiyalal; Desai, Amidevi; Gnanasegaran, Gopinath

    2015-01-01

    The facet joint has been increasingly implicated as a potential source of lower back pain. Diagnosis can be challenging as there is not a direct correlation between facet joint disease and clinical or radiological features. The purpose of this article is to review the diagnosis, treatment, and current imaging modality options in the context of degenerative facet joint disease. We describe each modality in turn with a pictorial review using current evidence. Newer hybrid imaging techniques such as single photon emission computed tomography/computed tomography (SPECT/CT) provide additional information relative to the historic gold standard magnetic resonance imaging. The diagnostic benefits of SPECT/CT include precise localization and characterization of spinal lesions and improved diagnosis for lower back pain. It may have a role in selecting patients for local therapeutic injections, as well as guiding their location with increased precision. PMID:26170560

  13. Radiological and Radionuclide Imaging of Degenerative Disease of the Facet Joints

    PubMed Central

    Shur, Natalie; Corrigan, Alexis; Agrawal, Kanhaiyalal; Desai, Amidevi; Gnanasegaran, Gopinath

    2015-01-01

    The facet joint has been increasingly implicated as a potential source of lower back pain. Diagnosis can be challenging as there is not a direct correlation between facet joint disease and clinical or radiological features. The purpose of this article is to review the diagnosis, treatment, and current imaging modality options in the context of degenerative facet joint disease. We describe each modality in turn with a pictorial review using current evidence. Newer hybrid imaging techniques such as single photon emission computed tomography/computed tomography (SPECT/CT) provide additional information relative to the historic gold standard magnetic resonance imaging. The diagnostic benefits of SPECT/CT include precise localization and characterization of spinal lesions and improved diagnosis for lower back pain. It may have a role in selecting patients for local therapeutic injections, as well as guiding their location with increased precision. PMID:26170560

  14. Prevalence of facet joint pain in chronic spinal pain of cervical, thoracic, and lumbar regions

    PubMed Central

    Manchikanti, Laxmaiah; Boswell, Mark V; Singh, Vijay; Pampati, Vidyasagar; Damron, Kim S; Beyer, Carla D

    2004-01-01

    Background Facet joints are a clinically important source of chronic cervical, thoracic, and lumbar spine pain. The purpose of this study was to systematically evaluate the prevalence of facet joint pain by spinal region in patients with chronic spine pain referred to an interventional pain management practice. Methods Five hundred consecutive patients with chronic, non-specific spine pain were evaluated. The prevalence of facet joint pain was determined using controlled comparative local anesthetic blocks (1% lidocaine or 1% lidocaine followed by 0.25% bupivacaine), in accordance with the criteria established by the International Association for the Study of Pain (IASP). The study was performed in the United States in a non-university based ambulatory interventional pain management setting. Results The prevalence of facet joint pain in patients with chronic cervical spine pain was 55% 5(95% CI, 49% – 61%), with thoracic spine pain was 42% (95% CI, 30% – 53%), and in with lumbar spine pain was 31% (95% CI, 27% – 36%). The false-positive rate with single blocks with lidocaine was 63% (95% CI, 54% – 72%) in the cervical spine, 55% (95% CI, 39% – 78%) in the thoracic spine, and 27% (95% CI, 22% – 32%) in the lumbar spine. Conclusion This study demonstrated that in an interventional pain management setting, facet joints are clinically important spinal pain generators in a significant proportion of patients with chronic spinal pain. Because these patients typically have failed conservative management, including physical therapy, chiropractic treatment and analgesics, they may benefit from specific interventions designed to manage facet joint pain. PMID:15169547

  15. Establishment of a rat model of adjuvant-induced osteoarthritis of the lumbar facet joint.

    PubMed

    Shuang, Feng; Zhu, Jialiang; Song, Keran; Hou, Shuxun; Liu, Yan; Zhang, Chunli; Tang, Jiaguang

    2014-12-01

    To study the establishment of adjuvant-induced osteoarthritis of the lumbar facet joint in a rat model. Complete Freund's adjuvant (experimental group) and saline (control group) were randomly injected into the right and left side of rat, respectively. The rats were killed, and degeneration of lumbar facet joint was evaluated at macroscopic level and scored based on OARSI scores system. Moreover, Interleukin-1β and tumor necrosis factor-α levels in the synovium were measured. The macroscopic scores and OARSI scores of experimental group were higher than the control group (P < 0.05). The concentration of tumor necrosis factor-α was significantly increased only on 3- and 7-day post-surgery when compared with controls, and interleukin-1β was increased on days 3,7 and 14 post-surgery (P < 0.05). The rat model of adjuvant can induce degeneration of the lumbar facet joint. It can be useful for studies on mechanisms and treatment of lumbar facet joint osteoarthritis. PMID:24973958

  16. Talocalcaneal Joint Middle Facet Coalition Resection With Interposition of a Juvenile Hyaline Cartilage Graft.

    PubMed

    Tower, Dyane E; Wood, Ryan W; Vaardahl, Michael D

    2015-01-01

    Talocalcaneal joint middle facet coalition is the most common tarsal coalition, occurring in ≤2% of the population. Fewer than 50% of involved feet obtain lasting relief of symptoms after nonoperative treatment, and surgical intervention is commonly used to relieve symptoms, increase the range of motion, improve function, reconstruct concomitant pes planovalgus, and prevent future arthrosis from occurring at the surrounding joints. Several approaches to surgical intervention are available for patients with middle facet coalitions, ranging from resection to hindfoot arthrodesis. We present a series of 4 cases, in 3 adolescent patients, of talocalcaneal joint middle facet coalition resection with interposition of a particulate juvenile hyaline cartilaginous allograft (DeNovo(®) NT Natural Tissue Graft, Zimmer, Inc., Warsaw, IN). With a mean follow-up period of 42.8 ± 2.9 (range 41 to 47) months, the 3 adolescent patients in the present series were doing well with improved subtalar joint motion and decreased pain, and 1 foot showed no bony regrowth on a follow-up computed tomography scan. The use of a particulate juvenile hyaline cartilaginous allograft as interposition material after talocalcaneal middle facet coalition resection combined with adjunct procedures to address concomitant pes planovalgus resulted in good short-term outcomes in 4 feet in 3 adolescent patients. PMID:25922335

  17. Chronic unilateral locked facet joint with spinal cord injury in a 26-month-old child: A case report

    PubMed Central

    Wu, Ai-Min; Wang, Xiang-Yang; Luo, Peng; Xu, Hua-Zi; Chi, Yong-Long

    2015-01-01

    Objectives This study presents the successful posterior surgical reduction and fusion on a 26-month-old child with chronic unilateral locked facet joint and spinal cord injury (SCI). Methods A 26-month-old child with chronic unilateral locked facet joint and SCI treated by posterior surgical reduction and fusion. Plaster external fixation was applied and rehabilitation exercise was trained post-operatively. Results Chronic unilateral locked facet joint was reduced successfully and bone fusion of C4/5 was achieved 3 months after surgery. The function of both lower limbs was improved 1 year after surgery, aided with physical rehabilitation. Conclusion Unilateral locked facet joint in pediatric population is rare. Few clinical experiences were found in the literature. Non-surgical treatment has advantages of not being invasive and is preferred for acute patients; however, it may not be suitable for chronic unilateral locked facet joint with SCI, in which surgical intervention is needed. PMID:24673578

  18. Characterization of subchondral bone histopathology of facet joint osteoarthritis in lumbar spinal stenosis.

    PubMed

    Netzer, Cordula; Urech, Karin; Hügle, Thomas; Benz, Robyn Melanie; Geurts, Jeroen; Schären, Stefan

    2016-08-01

    Facet joint osteoarthritis may be a cause of low back pain in degenerative spine diseases including lumbar spinal stenosis. Subchondral bone is regarded as a potential therapeutic target for osteoarthritis treatment. The goal of this study was to characterize subchondral bone histopathology in osteoarthritic facet joints from lumbar spinal stenosis patients. Fifteen patients with degenerative spinal stenosis scheduled for transforaminal lumbar interbody fusion surgery were recruited for this study. Osteoarthritis severity was graded on T1- and T2-weighted MRI images using Weishaupt scoring system. Dissected osteoarthritic facet joints were subjected to histological and immunohistochemistry analyses to study relative abundance of osteoblast, osteoclasts, and macrophages using van Gieson's, tartrate-resistant acid phosphatase and CD68-antibody staining, respectively. Presence of nerve fibers was evaluated by PGP9.5-antibody staining. Differential bone histopathology, independent from radiological osteoarthritis grade, was observed in facet joints. Extensive de novo bone formation was found in subchondral bone tissues of eight of fifteen specimens. Regions of bone formation showed high abundance of blood vessels and CD68-positive macrophages, but were devoid of multinucleated osteoclasts. Additional pathological changes in subchondral marrow spaces, including inflammatory infiltration and enhanced osteoclast activity, were characterized by macrophage-rich tissues. PGP9.5-positive nerve fibers were detected near arterioles, but not in regions displaying bone pathology. Individual histopathological parameters did not associate with clinical features or radiological osteoarthritis severity. Subchondral bone histopathology of facet joint osteoarthritis in lumbar spinal stenosis is characterized by marrow infiltration by macrophage-rich tissues and enhanced de novo bone formation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34

  19. Navigated Pin-Point Approach to Osteoid Osteoma Adjacent to the Facet Joint of Spine

    PubMed Central

    Neo, Masashi; Takemoto, Mitsuru; Nishizawa, Kazuya; Imai, Shinji

    2016-01-01

    Osteoid osteoma (OO) is a benign osteoblastic tumor. Its curative treatment is complete removal of the nidus, where intraoperative localization of the nidus governs clinical results. However, treatment can be difficult since the lesion is often invisible over the bony surface. Accordingly, establishment of an ideal less invasive surgical strategy for spinal OO remains yet unsettled. We illustrate the efficacy of a computed tomography (CT)-based navigation system in excising OO located adjacent to the facet joint of spine. In our 2 cases, complete and pin-point removal of the nidus located close to the facet joint was successfully achieved, without excessive removal of the bone potentially leading to spinal instability and possible damage of nearby neurovascular structures. We advocate a less invasive approach to spinal OO, particularly in an environment with an available CT-based navigation system. PMID:26949472

  20. Osseous associated cervical spondylomyelopathy at the C2-C3 articular facet joint in 11 dogs.

    PubMed

    Cooper, C; Gutierrez-Quintana, R; Penderis, J; Gonçalves, R

    2015-11-21

    In dogs, vertebral canal stenosis at C2-C3 due to articular facet joint degeneration is only sporadically identified. The authors' aims were to review the clinical presentation, MRI characteristics, treatment and outcome of dogs presenting with this condition. Eleven cases were eligible for inclusion. Neurological examination revealed tetraparesis and proprioceptive ataxia in all 4 limbs in 3/11, proprioceptive tetra-ataxia only in 4/11, pelvic limb proprioceptive ataxia in 2/11 and no gait abnormalities in 2/11 dogs. Cervical hyperaesthesia was present in 7/11 dogs. MRI revealed bilateral articular facet joint degeneration in 10/11 cases and unilateral degeneration in one. Surgery was performed in six cases and medical management elected in five. Long-term follow-up information was available for 11 animals. Four of the surgical cases are alive and have no neurological deficits, one was euthanased for an unrelated condition and one lost to follow-up. Of the cases managed medically, three are alive showing no neurological deficits, one is alive still displaying neurological deficits and one euthanased for an unrelated condition whilst still ataxic. This study shows that both medical and surgical management can result in good outcomes in dogs with vertebral canal stenosis resulting from articular facet joint degeneration at the level of C2-C3. PMID:26510824

  1. Evaluation of the stress distribution change at the adjacent facet joints after lumbar fusion surgery: a biomechanical study.

    PubMed

    Ma, Jianxiong; Jia, Haobo; Ma, Xinlong; Xu, Weiguo; Yu, Jingtao; Feng, Rui; Wang, Jie; Xing, Dan; Wang, Ying; Zhu, Shaowen; Yang, Yang; Chen, Yang; Ma, Baoyi

    2014-07-01

    Spinal fusion surgery has been widely applied in clinical treatment, and the spinal fusion rate has improved markedly. However, its postoperative complications, especially adjacent segment degeneration, have increasingly attracted the attention of spinal surgeons. The most common pathological condition at adjacent segments is hypertrophic degenerative arthritis of the facet joint. To study the stress distribution changes at the adjacent facet joint after lumbar fusion with pedicle screw fixation, human cadaver lumbar spines were used in the present study, and electrical resistance strain gauges were attached on L1-L4 articular processes parallel or perpendicular to the articular surface of facet joints. Subsequently, electrical resistance strain gauge data were measured using anYJ-33 static resistance strain indicator with three types of models: the intact model, the laminectomy model, and the fusion model with pedicle screw fixation. The strain changes in the measurement sites indirectly reflect the stress changes. Significant differences in strain were observed between the normal and laminectomy state at all facet joints. Significant differences in strain were observed between the normal and the pedicle screw fixation fusion state at the L1/2 and L3/4 facet joints. The increased stress on the facet joints after lumbar fusion with pedicle screw fixation may be the cause of adjacent segment degeneration. PMID:24963037

  2. CT-Guided Transfacet Pedicle Screw Fixation in Facet Joint Syndrome: A Novel Approach

    PubMed Central

    Manfré, Luigi

    2014-01-01

    Summary Axial microinstability secondary to disc degeneration and consequent chronic facet joint syndrome (CFJS) is a well-known pathological entity, usually responsible for low back pain (LBP). Although posterior lumbar fixation (PIF) has been widely used for lumbar spine instability and LBP, complications related to wrong screw introduction, perineural scars and extensive muscle dissection leading to muscle dysfunction have been described. Radiofrequency ablation (RFA) of facet joints zygapophyseal nerves conventionally used for pain treatment fails in approximately 21% of patients. We investigated a “covert-surgery” minimal invasive technique to treat local spinal instability and LBP, using a novel fully CT-guided approach in patients with axial instability complicated by CFJS resistant to radioablation, by introducing direct fully or partially threaded transfacet screws (transfacet fixation - TFF), to acquire solid arthrodesis, reducing instability and LBP. The CT-guided procedure was well tolerated by all patients in simple analogue sedation, and mean operative time was approximately 45 minutes. All eight patients treated underwent clinical and CT study follow-up at two months, revealing LBP disappearance in six patients, and a significant reduction of lumbar pain in two. In conclusion, CT-guided TFF is a fast and safe technique when facet posterior fixation is needed. PMID:25363265

  3. Morphometric Study of Clavicular Facet of Coracoclavicular Joint in Adult Indian Population

    PubMed Central

    Mahajan, Anita; Vasudeva, Neelam

    2016-01-01

    Introduction Anthropologists have used Coracoclavicular Joint (CCJ), a non-metric anatomical variant in population, as a marker for population migration from prehistoric times to present. Aim The aim of this osteological study was to determine the incidence and morphometry of articular facet of CCJ on conoid tubercle of clavicle in Indian population, as Indian studies are scanty and incomplete. Materials and Methods The study was done on 144 adult human clavicles (76 right and 68 left; 93 males and 51 females) collected from osteology museum in Department of Anatomy, Maulana Azad Medical College, New Delhi, India. The presence of articular facet on the conoid tubercle was determined and Maximum Antero-Posterior (MAPD) and maximum transverse diameter (MTD) was measured by digital vernier calliper. The incidence was compared on the basis of sex, side and with other osteological studies in the world. Statistical analysis was done using the Chi-Square test for nominal categorical data and student’s t-test for normally distributed continuous variables in Microsoft Excel 2007 to assess the relationship between the examined variables. Results Articular facet on conoid tubercle was found in 8 cases (5.6%). Seven (9.2%) were present on the right side and one (1.5%) on the left side. Seven cases (7.5%) were present in males and one case (2%) was found in females. The facets were generally oval, with MAPD and MTD of 12.28 and 17.17 mm respectively. A significant side variation was present with right sided facet being more common. The left sided facet was more transversely elongated than right. In males, the facets were more elongated antero-posteriorly than in females. Conclusion The Indian population showed an incidence of 5.6%, which was comparable to other ethnic groups in world population. The morphometric and side differences could be attributed to the occupational factors and range of movements associated with the CCJ. The CCJ should be borne in mind as a differential

  4. Prediction of the human thoracic and lumbar articular facet joint morphometry from radiographic images

    PubMed Central

    Kunkel, Maria E; Schmidt, Hendrik; Wilke, Hans-Joachim

    2011-01-01

    The articular facet joints (AFJ) play an important role in the biomechanics of the spine. Although it is well known that some AFJ dimensions (e.g. facet height/width or facet angles) play a major role in spinal deformities such as scoliosis, little is known about statistical correlations between these dimensions and the size of the vertebral bodies. Such relations could allow patient-specific prediction of AFJ morphometry from a few dimensions measurable by X-ray. This would be of clinical interest and could also provide parameters for mathematical modeling of the spine. Our purpose in this study was to generate prediction equations for 20 parameters of the human thoracic and lumbar AFJ from T1 to L4 as a function of only one given parameter, the vertebral body height posterior (VBHP). Linear and nonlinear regression analyses were performed with published anatomical data, including linear and angular dimensions of the AFJ and vertebral body heights, to find the best functions to describe the correlations between these parameters. Third-order polynomial regressions, in contrast to the linear, exponential and logarithmic regressions, provided moderate to high correlations between the AFJ parameters and vertebral body heights; e.g. facet height superior and interfacet width (R2, 0.605–0.880); facet height inferior, interfacet height and sagittal/transverse angle superior (R2, 0.875–0.973). Different correlations were found for facet width and transverse angle inferior in the thoracic (R2, 0.703–0.930) and lumbar (R2, 0.457–0.892) regions. A set of 20 prediction equations for AFJ parameters was generated (P-values < 0.005, anova). Comparison of the AFJ predictions with experimental data indicated mean percent errors < 13%, with the exception of the thoracolumbar junction (T12–L1). It was possible to establish useful predictions for human thoracic and lumbar AFJ dimensions based on the size of the vertebral bodies. The generated set of equations allows the

  5. Does therapist’s attitude affect clinical outcome of lumbar facet joint injections?

    PubMed Central

    Middendorp, Marcus; Kollias, Konstantinos; Ackermann, Hanns; Splettstößer, Annina; Vogl, Thomas J; Khan, M Fawad; Maataoui, Adel

    2016-01-01

    AIM: To investigate if the clinical outcome of intra-articular lumbar facet joint injections is affected by the therapist’s attitude. METHODS: A total of 40 patients with facet joint-associated chronic low back pain were randomly divided into two groups. All patients received computed tomography-guided, monosegmental intra-articular facet joint injections. Following the therapeutic procedure, the patients of the experimental group (EG) held a conversation with the radiologist in a comfortable atmosphere. During the dialog, the patients were encouraged to ask questions and were shown four images. The patients of the control group (CG) left the clinic without any further contact with the radiologist. Outcome was assessed using a pain-based Verbal Numeric Scale at baseline, at 1 wk and at 1, 3, and 6 mo after first treatment. RESULTS: The patient demographics showed no differences between the groups. The patients of the EG received 57 interventional procedures in total, while the patients of the CG received 70 interventional procedures. In both groups, the pain scores decreased significantly over the entire observation period. Compared to the CG, the EG showed a statistically significant reduction of pain at 1 wk and 1 mo post-treatment, while at 3 and 6 mo after treatment, there were no significant differences between both groups. CONCLUSION: Our results show a significant effect on pain relief during the early post-interventional period in the EG as compared to the CG. The basic principle behind the higher efficacy might be the phenomenon of hetero-suggestion. PMID:27358691

  6. Facet joint septic arthritis due to community acquired methicillin resistant Staphylococcus aureus (MRSA) - A case report.

    PubMed

    Purushothaman, Rajesh; Inassi, Jojo; Marthya, Anwar

    2015-10-01

    Septic arthritis of facet joint (SAFJ) is extremely rare. Only about sixty cases have been reported so far. A single case of SAFJ in a series of 491 cases of spinal infections was first reported by David-Chaussé in 1981. A case report of SAFJ was published by Halpin in 1987. With the growing availability and use of MRI, more and more cases are being reported. The most common organism that causes SAFJ is Staphylococcus aureus. We are reporting a case of SAFJ caused by community acquired, methicillin resistant S aureus (MRSA) successfully treated by Linezolid. PMID:26719620

  7. Idiopathic septic arthritis of a lumbar facet joint associated with paraspinal abscess.

    PubMed

    Kitova-John, Margarita Borislavova; Azim-Araghi, Ali; Sheikh, Faraz Tariq; Kitov, Borislav Dimitrov

    2015-01-01

    A 48-year-old woman presented with a 1-month history of severe lower back pain on a background of 24 h of mild fever and general tiredness with an associated right-sided foot drop. Five weeks after the onset and with no improvement in symptoms in spite of analgesia and physiotherapy, the patient had a lumbar spine MRI which demonstrated a collection extending from the facet joints of L5 and L6 to the iliacus muscle on the right. A CT-guided aspiration was performed with a lengthy hospital stay for intravenous antibiotic treatment. The culture and sensitivity study of the aspirate isolated Streptococcus pneumoniae. PMID:26272966

  8. Septic arthritis of a lumbar facet joint: Detection with bone SPECT imaging

    SciTech Connect

    Swayne, L.C.; Dorsky, S.; Caruana, V.; Kaplan, I.L. )

    1989-08-01

    We present a rare case of septic arthritis of a lumbar facet joint with an associated epidural abscess resulting from Staphylococcus aureus. The infection was initially detected with planar bone scintigraphy and precisely localized with single photon emission computed tomography bone scintigraphy, despite an initially negative radiologic evaluation that included radiographs of the lumbar spine, lumbar myelography, and a postmyelography x-ray computed tomography scan. In the appropriate clinical setting, a bone scan demonstrating unilateral increased activity within the spine should raise the suspicion of inflammatory involvement of the posterior elements.

  9. Morphological and biomechanical analyses of the subchondral mineralized zone in human sacral facet joints: Application to improved diagnosis of osteoarthritis.

    PubMed

    Berteau, Jean-Philippe; Mielke, Gabriela; Morlock, Michael M; Huber, Gerd

    2015-05-01

    The anatomy of the facet joint subchondral mineralized zone (SMZ) is the main parameter used in diagnosing osteoarthritis. Usually, a single CT scan slice is used to measure the thickness, but the measurement is highly location-dependent. Bone mineral density (BMD) and porosity could be more reliable than thickness for detecting SMZ sclerosis, and linking them to stiffness can provide insights into the mechanism of osteoarthritis progression. The goal of this study was two-fold: (1) to assess spatial heterogeneity in thickness, BMD, and porosity within the non-pathological human facet joint SMZ; (2) to correlate these measurements with the static modulus of elasticity (MOEsta ). Four non-pathological facet joints were excised and imaged using micro-computed tomography (µCT) to measure SMZ thickness, BMD, and porosity. A total of eight parallelepiped SMZ samples were similarly analyzed and then mechanically tested. The mean SMZ BMD, porosity, and thickness (± Standard Deviation) of the whole facet joints were 611 ± 35 mgHA/cc, 9.8 ± 1.3%, and 1.39 ± 0.41 mm, respectively. The mean BMD, porosity, and MOEsta of the eight SMZ samples were 479 ± 23 mgHA/cc, 12 ± 0.01%, and 387 ± 138 MPa, respectively, with a positive rank correlation between BMD and porosity. BMD and porosity were more homogeneous within the facet joint than thickness and they could be more reliable parameters than thickness for detecting SMZ sclerosis. The values for the physiological SMZ and MOEsta of human facets joints obtained here were independent of BMD. SMZ BMD and porosity were related to each other. PMID:25716678

  10. THE PROSTAGLANDIN E2 RECEPTOR, EP2, IS UPREGULATED IN THE DRG AFTER PAINFUL CERVICAL FACET JOINT INJURY IN THE RAT

    PubMed Central

    Kras, Jeffrey V.; Dong, Ling; Winkelstein, Beth A.

    2012-01-01

    Study Design This study implemented immunohistochemistry to assay prostaglandin E2 (PGE2) receptor EP2 expression in the dorsal root ganglion (DRG) of rats after painful cervical facet joint injury. Objective The objective of this study was to identify if inflammatory cascades are induced in association with cervical facet joint distraction-induced pain by investigating the time course of EP2 expression in the DRG. Summary of Background Data The cervical facet joint is a common source of neck pain and non-physiological stretch of the facet capsular ligament can initiate pain from the facet joint via mechanical injury. PGE2 levels are elevated in painful inflamed and arthritic joints, and PGE2 sensitizes joint afferents to mechanical stimulation. Although in vitro studies suggest the EP2 receptor subtype contributes to painful joint disease the EP2 response has not been investigated for any association with painful mechanical joint injury. Methods Separate groups of male Holtzman rats underwent either a painful cervical facet joint distraction injury or sham procedure. Bilateral forepaw mechanical allodynia was assessed, and immunohistochemical techniques were used to quantify EP2 expression in the DRG at days 1 and 7. Results Facet joint distraction induced mechanical allodynia that was significant (p<0.024) at all time points. Painful joint injury also significantly elevated total EP2 expression in the DRG at day 1 (p=0.009), which was maintained also at day 7 (p<0.001). Neuronal expression of EP2 in the DRG was only increased over sham levels at day 1 (p=0.013). Conclusions Painful cervical facet joint distraction induces an immediate and sustained increase of EP2 expression in the DRG, implicating peripheral inflammation in the initiation and maintenance of facet joint pain. The transient increase in neuronal EP2 suggests, as in other painful joint conditions, that after joint injury non-neuronal cells may migrate to the DRG, some of which likely express EP2

  11. Injection in the cervical facet joint for shoulder pain with myofascial trigger points in the upper trapezius muscle.

    PubMed

    Tsai, Chien-Tsung; Hsieh, Lin-Fen; Kuan, Ta-Shen; Kao, Mu-Jung; Hong, Chang-Zern

    2009-08-01

    The goal of this double-blinded, randomized, controlled study was to confirm the effectiveness of the cervical facet joint injection in treating shoulder pain with the myofascial trigger point in the upper trapezius muscle secondary to cervical facet lesion. Eighty-nine patients with chronic unilateral shoulder pain due to myofascial trigger points in the upper trapezius muscle received an injection to the C4-5 facet joint in the experimental group and to the corresponding unilateral multifidi muscle in the control group. Subjective pain intensity and pressure pain threshold of the myofascial trigger point were assessed, and the prevalence of endplate noise in the myofascial trigger point region was measured in 28 patients before, immediately after, and 1 month after the injection. Half of the patients in the experimental group, but none of the control patients, reported being completely pain free 1 month after the injection. Both the decrease in the pain intensity and the increase in pressure pain threshold were significantly more in the experimental group than in the control group either immediately or 1 month after the injection. There was no significant difference in the change of endplate noise prevalence between the 2 groups. This study demonstrates that intra-articular or peri-articular injection into the cervical facet joint region can effectively inactivate the upper trapezius myofascial trigger point secondary to the facet lesion. PMID:19708635

  12. A Cervico-Thoraco-Lumbar Multibody Dynamic Model for the Estimation of Joint Loads and Muscle Forces.

    PubMed

    Khurelbaatar, Tsolmonbaatar; Kim, Kyungsoo; Hyuk Kim, Yoon

    2015-11-01

    Computational musculoskeletal models have been developed to predict mechanical joint loads on the human spine, such as the forces and moments applied to vertebral and facet joints and the forces that act on ligaments and muscles because of difficulties in the direct measurement of joint loads. However, many whole-spine models lack certain elements. For example, the detailed facet joints in the cervical region or the whole spine region may not be implemented. In this study, a detailed cervico-thoraco-lumbar multibody musculoskeletal model with all major ligaments, separated structures of facet contact and intervertebral disk joints, and the rib cage was developed. The model was validated by comparing the intersegmental rotations, ligament tensile forces, facet joint contact forces, compressive and shear forces on disks, and muscle forces were to those reported in previous experimental and computational studies both by region (cervical, thoracic, or lumbar regions) and for the whole model. The comparisons demonstrated that our whole spine model is consistent with in vitro and in vivo experimental studies and with computational studies. The model developed in this study can be used in further studies to better understand spine structures and injury mechanisms of spinal disorders. PMID:26292160

  13. Explosive growth of facet joint interventions in the medicare population in the United States: a comparative evaluation of 1997, 2002, and 2006 data

    PubMed Central

    2010-01-01

    Background The Office of Inspector General of the Department of Health and Human Services (OIG-DHHS) issued a report which showed explosive growth and also raised questions of lack of medical necessity and/or indications for facet joint injection services in 2006. The purpose of the study was to determine trends of frequency and cost of facet joint interventions in managing spinal pain. Methods This analysis was performed to determine trends of frequency and cost of facet joint Interventions in managing spinal pain, utilizing the annual 5% national sample of the Centers for Medicare and Medicaid Services (CMS) for 1997, 2002, and 2006. Outcome measures included overall characteristics of Medicare beneficiaries receiving facet joint interventions, utilization of facet joint interventions by place of service, by specialty, reimbursement characteristics, and other variables. Results From 1997 to 2006, the number of patients receiving facet joint interventions per 100,000 Medicare population increased 386%, facet joint visits increased 446%, and facet joint interventions increased 543%. The increases were higher in patients aged less than 65 years compared to those 65 or older with patients increasing 504% vs. 355%, visits increasing 587% vs. 404%, and services increasing 683% vs. 498%. Total expenditures for facet joint interventions in the Medicare population increased from over $229 million in 2002 to over $511 million in 2006, with an overall increase of 123%. In 2006, there was a 26.8-fold difference in utilization of facet joint intervention services in Florida compared to the state with the lowest utilization - Hawaii. There was an annual increase of 277.3% in the utilization of facet joint interventions by general physicians, whereas a 99.5% annual increase was seen for nurse practitioners (NPs) and certified registered nurse anesthetists (CRNAs) from 2002 to 2006. Further, in Florida, 47% of facet joint interventions were performed by general physicians

  14. Evaluation of Lumbar Facet Joint Nerve Blocks in Managing Chronic Low Back Pain: A Randomized, Double-Blind, Controlled Trial with a 2-Year Follow-Up

    PubMed Central

    Manchikanti, Laxmaiah; Singh, Vijay; Falco, Frank J.E.; Cash, Kimberly A.; Pampati, Vidyasagar

    2010-01-01

    Study Design: A randomized, double-blind, controlled trial. Objective: To determine the clinical effectiveness of therapeutic lumbar facet joint nerve blocks with or without steroids in managing chronic low back pain of facet joint origin. Summary of Background Data: Lumbar facet joints have been shown as the source of chronic pain in 21% to 41% of low back patients with an average prevalence of 31% utilizing controlled comparative local anesthetic blocks. Intraarticular injections, medial branch blocks, and radiofrequency neurotomy of lumbar facet joint nerves have been described in the alleviation of chronic low back pain of facet joint origin. Methods: The study included 120 patients with 60 patients in each group with local anesthetic alone or local anesthetic and steroids. The inclusion criteria was based upon a positive response to diagnostic controlled, comparative local anesthetic lumbar facet joint blocks. Outcome measures included the numeric rating scale (NRS), Oswestry Disability Index (ODI), opioid intake, and work status, at baseline, 3, 6, 12, 18, and 24 months. Results: Significant improvement with significant pain relief of ≥ 50% and functional improvement of ≥ 40% were observed in 85% in Group 1, and 90% in Group II, at 2-year follow-up. The patients in the study experienced significant pain relief for 82 to 84 weeks of 104 weeks, requiring approximately 5 to 6 treatments with an average relief of 19 weeks per episode of treatment. Conclusions: Therapeutic lumbar facet joint nerve blocks, with or without steroids, may provide a management option for chronic function-limiting low back pain of facet joint origin. PMID:20567613

  15. 18F-Sodium Fluoride PET-CT Hybrid Imaging of the Lumbar Facet Joints: Tracer Uptake and Degree of Correlation to CT-graded Arthropathy

    PubMed Central

    Mabray, Marc C.; Brus-Ramer, Marcel; Behr, Spencer C.; Pampaloni, Miguel H.; Majumdar, Sharmila; Dillon, William P.; Talbott, Jason F.

    2016-01-01

    We aim to evaluate 18F-NaF uptake by facet joints with hybrid PET-CT technique. Specifically, we evaluate NaF uptake in the facet joints of the lower lumbar spine, and correlate with the morphologic grade of facet arthropathy on CT. 30 consecutive patients who underwent standard vertex to toes NaF PET-CT for re-staging of primary neoplastic disease without measurable or documented bony metastases were identified. Maximum (SUVmax) and average (SUVavg) standardized uptake values were calculated for each L3-4, L4-5, and L5-S1 facet joint (n = 180) and normalized to average uptake in the non-diseased femur. A Pathria grade (0-3) was assigned to each facet based upon the CT morphology. Spearman's rank correlation was performed for normalized SUVmax and SUVavg with Pathria grade. ANOVA was performed with Tukey-Kramer pairwise tests to evaluate differences in uptake between Pathria groups. Facet normalized SUVmax (r = 0.31, P < 0.001) and SUVavg (r = 0.28, P < 0.001) demonstrated a mild positive correlation with CT Pathria grade. There was a wide range of uptake values within each Pathria grade subgroup with statistically significant differences in uptake only between Pathria grade 3 as compared to grades 0, 1, and 2. In conclusion, NaF uptake and morphologic changes of the facet joint on CT are weakly correlated. Physiologic information provided by NaF uptake is often discrepant with structural findings on CT suggesting NaF PET may supplement conventional structural imaging for identification of pain generating facet joints. Prospective investigation into the relationship of facet joint NaF uptake with pain and response to pain interventions is warranted. PMID:27134557

  16. (18)F-Sodium Fluoride PET-CT Hybrid Imaging of the Lumbar Facet Joints: Tracer Uptake and Degree of Correlation to CT-graded Arthropathy.

    PubMed

    Mabray, Marc C; Brus-Ramer, Marcel; Behr, Spencer C; Pampaloni, Miguel H; Majumdar, Sharmila; Dillon, William P; Talbott, Jason F

    2016-01-01

    We aim to evaluate (18)F-NaF uptake by facet joints with hybrid PET-CT technique. Specifically, we evaluate NaF uptake in the facet joints of the lower lumbar spine, and correlate with the morphologic grade of facet arthropathy on CT. 30 consecutive patients who underwent standard vertex to toes NaF PET-CT for re-staging of primary neoplastic disease without measurable or documented bony metastases were identified. Maximum (SUVmax) and average (SUVavg) standardized uptake values were calculated for each L3-4, L4-5, and L5-S1 facet joint (n = 180) and normalized to average uptake in the non-diseased femur. A Pathria grade (0-3) was assigned to each facet based upon the CT morphology. Spearman's rank correlation was performed for normalized SUVmax and SUVavg with Pathria grade. ANOVA was performed with Tukey-Kramer pairwise tests to evaluate differences in uptake between Pathria groups. Facet normalized SUVmax (r = 0.31, P < 0.001) and SUVavg (r = 0.28, P < 0.001) demonstrated a mild positive correlation with CT Pathria grade. There was a wide range of uptake values within each Pathria grade subgroup with statistically significant differences in uptake only between Pathria grade 3 as compared to grades 0, 1, and 2. In conclusion, NaF uptake and morphologic changes of the facet joint on CT are weakly correlated. Physiologic information provided by NaF uptake is often discrepant with structural findings on CT suggesting NaF PET may supplement conventional structural imaging for identification of pain generating facet joints. Prospective investigation into the relationship of facet joint NaF uptake with pain and response to pain interventions is warranted. PMID:27134557

  17. Establishment of a rat model of lumbar facet joint osteoarthritis using intraarticular injection of urinary plasminogen activator.

    PubMed

    Shuang, Feng; Hou, Shu-Xun; Zhu, Jia-Liang; Liu, Yan; Zhou, Ying; Zhang, Chun-Li; Tang, Jia-Guang

    2015-01-01

    Lumbar facet joint (LFJ) osteoarthritis (OA) is an important etiology of low back pain. Several animal models of LFJ OA have been established using intraarticular injection of various chemicals. This study aimed to establish a rat model of LFJ OA using urinary plasminogen activator (uPA). Sprague-Dawley rats were treated with intraarticular injection in the L5-L6 facet joints with uPA (OA group, n = 40) or normal saline (vehicle group, n = 40). Mechanical and thermal hyperalgesia in the ipsilateral hind paws were evaluated using von Frey hairs and a thermoalgesia instrument, respectively. Toluidine blue staining, hematoxylin-eosin staining, and immunohistochemical examination of the LFJ was performed. Treatment with uPA induced cartilage damage, synovitis, and proliferation of synovial cells in the fact joints. The OA group showed significantly higher hyperalgesia in the hind paws in comparison with the vehicle group and normal controls (P < 0.05). Expression of IL-1β, TNF-α, and iNOS in the LFJ cartilage in the OA group was significantly increased (P < 0.05). A rat model of LFJ OA was successfully established using intraarticular injection of uPA. This animal model is convenient and shows good resemblance to human OA pathology. PMID:25892493

  18. BSA Nanoparticle Loaded Atorvastatin Calcium - A New Facet for an Old Drug

    PubMed Central

    S, Sripriyalakshmi.; C. H, Anjali.; C, George Priya Doss.; B, Rajith; Ravindran, Aswathy

    2014-01-01

    Background Currently, the discovery of effective chemotherapeutic agents poses a major challenge to the field of cancer biology. The present study focuses on enhancing the therapeutic and anti cancer properties of atorvastatin calcium loaded BSA (ATV-BSA) nanoparticles in vitro. Methodology/Results BSA-ATV nanoparticles were prepared using desolvation technique. The process parameters were optimized based on the amount of desolvating agent, stabilization conditions as well as the concentration of the cross linker. The anti cancer properties of the protein coated ATV nanoparticles were tested on MiaPaCa-2 cell lines. In vitro release behavior of the drug from the carrier suggests that about 85% of the drug gets released after 72 hrs. Our studies show that ATV-BSA nanoparticles showed specific targeting and enhanced cytotoxicity to MiaPaCa-2 cells when compared to the bare ATV. Conclusion We hereby propose that the possible mechanism of cellular uptake of albumin bound ATV could be through caveolin mediated endocytosis. Hence our studies open up new facet for an existing cholesterol drug as a potent anti-cancer agent. PMID:24498272

  19. TECHNIQUE, DIFFICULTY, AND ACCURACY OF COMPUTED TOMOGRAPHY-GUIDED TRANSLAMINAR AND TRANSFORAMINAL LUMBOSACRAL EPIDURAL AND INTRAARTICULAR LUMBAR FACET JOINT INJECTIONS IN DOGS.

    PubMed

    Liotta, Annalisa; Sandersen, Charlotte; Couvreur, Thierry; Bolen, Géraldine

    2016-01-01

    In human medicine, spinal pain and radiculopathy are commonly managed by computed tomography (CT)-guided facet joint injections and by transforaminal or translaminar epidural injections. In dogs, CT-guided lumbosacral epidural or lumbar facet joint injections have not been described. The aim of this experimental, ex vivo, feasibility study was to develop techniques and to assess their difficulty and accuracy. Two canine cadavers were used to establish the techniques and eight cadavers to assess difficulty and accuracy. Contrast medium was injected and a CT scan was performed after each injection. Accuracy was assessed according to epidural or joint space contrast opacification. Difficulty was classified as easy, moderately difficult, or difficult, based on the number of CT scans needed to guide insertion of the needle. A total of six translaminar and five transforaminal epidural and 53 joint injections were performed. Translaminar injections had a high success rate (100%), were highly accurate (75%), and easy to perform (100%). Transforaminal injections had an moderately high success rate (75%), were accurate (75%), and moderately difficult to perform (100%). Success rate of facet joint injections was 62% and was higher for larger facet joints, such as L7-S1. Accuracy of facet joint injections ranged from accurate (37-62%) to highly accurate (25%) depending on the volume injected. In 77% of cases, injections were moderately difficult to perform. Possible complications of epidural and facet joint injections were subarachnoid and vertebral venous plexus puncture and periarticular spread, respectively. Further studies are suggested to evaluate in vivo feasibility and safety of these techniques. PMID:26693948

  20. Calcium Carbonate Nanoplate Assemblies with Directed High-Energy Facets: Additive-Free Synthesis, High Drug Loading, and Sustainable Releasing.

    PubMed

    Zhang, Jing; Li, Yu; Xie, Hao; Su, Bao-Lian; Yao, Bin; Yin, Yixia; Li, Shipu; Chen, Fang; Fu, Zhengyi

    2015-07-29

    Developing drug delivery systems (DDSs) with high drug-loading capacity and sustainable releasing is critical for long-term chemotherapeutic efficacy, and it still remains challenging. Herein, vaterite CaCO3 nanoplate assemblies with exposed high-energy {001} facets have been synthesized via a novel, additive-free strategy. The product shows a high doxorubicin-loading capacity (65%); the best of all the CaCO3-based DDSs so far. Also, the product's sustainable releasing performance and its inhibition of the initial burst release, together, endow it with long-term drug efficacy. The work may shed light on exposing directed high-energy facets for rationally designing of a drug delivery system with long-term efficacy. PMID:26161808

  1. Biomechanical analysis of press-extension technique on degenerative lumbar with disc herniation and staggered facet joint.

    PubMed

    Du, Hong-Gen; Liao, Sheng-Hui; Jiang, Zhong; Huang, Huan-Ming; Ning, Xi-Tao; Jiang, Neng-Yi; Pei, Jian-Wei; Huang, Qin; Wei, Hui

    2016-05-01

    This study investigates the effect of a new Chinese massage technique named "press-extension" on degenerative lumbar with disc herniation and facet joint dislocation, and provides a biomechanical explanation of this massage technique. Self-developed biomechanical software was used to establish a normal L1-S1 lumbar 3D FE model, which integrated the spine CT and MRI data-based anatomical structure. Then graphic technique is utilized to build a degenerative lumbar FE model with disc herniation and facet joint dislocation. According to the actual press-extension experiments, mechanic parameters are collected to set boundary condition for FE analysis. The result demonstrated that press-extension techniques bring the annuli fibrosi obvious induction effect, making the central nucleus pulposus forward close, increasing the pressure in front part. Study concludes that finite element modelling for lumbar spine is suitable for the analysis of press-extension technique impact on lumbar intervertebral disc biomechanics, to provide the basis for the disease mechanism of intervertebral disc herniation using press-extension technique. PMID:27275119

  2. Issues related to SPR joints subjected to fatigue loads

    NASA Astrophysics Data System (ADS)

    De Luca, A.; Senatore, F.; Greco, A.

    2016-05-01

    SPR joints will represent an alternative solution to spot welding in automotive field. However, their fatigue behavior shows several critical issues. After a brief introduction of this new solution, different crack modes are described, emphasizing the parameters that characterize them, i.e. the applied loads, the geometry of the joint and other phenomenon as fretting, vibration and corrosion.

  3. Fluoroscopic caudal epidural injections in managing chronic axial low back pain without disc herniation, radiculitis, or facet joint pain

    PubMed Central

    Manchikanti, Laxmaiah; Cash, Kimberly A; McManus, Carla D; Pampati, Vidyasagar

    2012-01-01

    Background Chronic low back pain without disc herniation is common. Various modalities of treatments are utilized in managing this condition, including epidural injections. However, there is continued debate on the effectiveness, indications, and medical necessity of any treatment modality utilized for managing axial or discogenic pain, including epidural injections. Methods A randomized, double-blind, actively controlled trial was conducted. The objective was to evaluate the ability to assess the effectiveness of caudal epidural injections of local anesthetic with or without steroids for managing chronic low back pain not caused by disc herniation, radiculitis, facet joints, or sacroiliac joints. A total of 120 patients were randomized to two groups; one group did not receive steroids (group 1) and the other group did (group 2). There were 60 patients in each group. The primary outcome measure was at least 50% improvement in Numeric Rating Scale and Oswestry Disability Index. Secondary outcome measures were employment status and opioid intake. These measures were assessed at 3, 6, 12, 18, and 24 months after treatment. Results Significant pain relief and functional status improvement (primary outcome) defined as a 50% or more reduction in scores from baseline, were observed in 54% of patients in group 1 and 60% of patients in group 2 at 24 months. In contrast, 84% of patients in group 1 and 73% in group 2 saw significant pain relief and functional status improvement in the successful groups at 24 months. Conclusion Caudal epidural injections of local anesthetic with or without steroids are effective in patients with chronic axial low back pain of discogenic origin without facet joint pain, disc herniation, and/or radiculitis. PMID:23091395

  4. Analysis of the load on the knee joint and vertebral column with changes in squatting depth and weight load.

    PubMed

    Hartmann, Hagen; Wirth, Klaus; Klusemann, Markus

    2013-10-01

    It has been suggested that deep squats could cause an increased injury risk of the lumbar spine and the knee joints. Avoiding deep flexion has been recommended to minimize the magnitude of knee-joint forces. Unfortunately this suggestion has not taken the influence of the wrapping effect, functional adaptations and soft tissue contact between the back of thigh and calf into account. The aim of this literature review is to assess whether squats with less knee flexion (half/quarter squats) are safer on the musculoskeletal system than deep squats. A search of relevant scientific publications was conducted between March 2011 and January 2013 using PubMed. Over 164 articles were included in the review. There are no realistic estimations of knee-joint forces for knee-flexion angles beyond 50° in the deep squat. Based on biomechanical calculations and measurements of cadaver knee joints, the highest retropatellar compressive forces and stresses can be seen at 90°. With increasing flexion, the wrapping effect contributes to an enhanced load distribution and enhanced force transfer with lower retropatellar compressive forces. Additionally, with further flexion of the knee joint a cranial displacement of facet contact areas with continuous enlargement of the retropatellar articulating surface occurs. Both lead to lower retropatellar compressive stresses. Menisci and cartilage, ligaments and bones are susceptible to anabolic metabolic processes and functional structural adaptations in response to increased activity and mechanical influences. Concerns about degenerative changes of the tendofemoral complex and the apparent higher risk for chondromalacia, osteoarthritis, and osteochondritis in deep squats are unfounded. With the same load configuration as in the deep squat, half and quarter squat training with comparatively supra-maximal loads will favour degenerative changes in the knee joints and spinal joints in the long term. Provided that technique is learned accurately

  5. Stud Reinforcement in Beam-Column Joints under Seismic Loads

    NASA Astrophysics Data System (ADS)

    Ibrahim, Hatem Hassan Ali

    Current codes recommend large amounts of shear reinforcement for reinforced concrete beam-column joints causing significant congestion. This research aims at investigating experimentally and numerically the efficiency of using studs with a head at each end in lieu of conventional closed hoops in reinforced concrete beam-column joints. The proposed reinforcement reduces congestion and ensures easier assembly of the reinforcing cage, saving labour cost and enhancing performance of the joint. Based on this research, a recommended arrangement and detailing of headed studs and their design for exterior beam-column joint are presented. The experimental investigation consisted of testing ten full-scale beam-column joint specimens under quasi-static cyclic loading. The specimens represented an exterior beam-column joint subassembly isolated at the points of contra-flexure from a typical multi-storey, multi-bay reinforced concrete frame. A test setup was developed to simulate the lateral inter-storey drift. The test parameters included: the type, arrangement and amount of shear reinforcement, the load history and rate of loading, and the amount of reinforcement for out-of-plane confinement of the joint. Envelopes of the hysteretic behaviour of the specimens and the joint deformation under shear stress are presented. The stiffness degradation, the strain levels in the joint reinforcement, the contribution of joint, beam, and column to the inter-storey drift, and the energy dissipation were compared. All the test specimens reinforced with headed studs in the joint achieved considerable enhancement in their behaviour under cyclic loads and exhibited a performance close to that of a joint reinforced with closed hoops and cross ties according to the code. All the specimens with adequate out-of-plane confinement had an equivalent behaviour compared with the code-based specimen and achieved a desirable mode of failure. Use of double-headed studs proved to be a viable option for

  6. The behavior of reinforced concrete knee joints under earthquake loads

    NASA Astrophysics Data System (ADS)

    Angelakos, Bill

    The poor performance of knee joint connections during recent earthquakes motivated a number of experimental investigations of knee joint behavior under reversed cyclic loading. In this work the knee joint design problem is studied through a collective evaluation of the available experimental results and analytical modeling. The objective is to identify the critical response variables controlling the mechanics of knee joints under earthquake loads and to quantify the influence they have on the strength and deformation capacity of the joint. A knee joint model is derived from simple mechanical constructs of equilibrium and compatibility. The parametric dependence of knee joint behavior is investigated for critical design parameters such as concrete strength, amounts and yield strengths of horizontal and vertical transverse reinforcement, and bond demand. Three different limiting equations are developed from the model limiting the joint shear resistance according with the three alternative modes of joint shear failure. These are: (i) yielding of horizontal and vertical transverse reinforcement, (ii) and (iii) yielding in either of the two principal reinforcing directions accompanied by crushing of the concrete in compression (here the softening influence of orthogonal tensile deformations is considered). For those test specimens from the experimental database that experienced a joint shear failure, the simple knee joint model predicts their joint shear capacity well. Consistent with observations from interior connections it is shown that anchorage of the main reinforcement in the knee joint region prevails as the determining factor of the response of the joint panel. In addition, the same basic physical model that describes the source of resistance in interior connections also applies to knee joints; truss action, and diagonal strut action. By favorably anchoring the beam and column bars it is possible to develop the joint shear strength which is associated with one

  7. Indian Hedgehog signaling pathway members are associated with magnetic resonance imaging manifestations and pathological scores in lumbar facet joint osteoarthritis

    NASA Astrophysics Data System (ADS)

    Shuang, Feng; Zhou, Ying; Hou, Shu-Xun; Zhu, Jia-Liang; Liu, Yan; Zhang, Chun-Li; Tang, Jia-Guang

    2015-05-01

    Indian Hedgehog (HH) has been shown to be involved in osteoarthritis (OA) in articular joints, where there is evidence that Indian HH blockade could ameliorate OA. It seems to play a prominent role in development of the intervertebral disc (IVD) and in postnatal maintenance. There is little work on IHH in the IVD. Hence the aim of the current study was to investigate the role of Indian Hedgehog in the pathology of facet joint (FJ) OA. 24 patients diagnosed with lumbar intervertebral disk herniation or degenerative spinal stenosis were included. Preoperative magnetic resonance imaging (MRI) and Osteoarthritis Research Society International (OARSI) histopathology grading system was correlated to the mRNA levels of GLI1, PTCH1, and HHIP in the FJs. The Weishaupt grading and OARSI scores showed high positive correlation (r = 0.894) (P < 0.01). MRI Weishaupt grades showed positive correlation with GLI1 (r = 0.491), PTCH1 (r = 0.444), and HHIP (r = 0.654) mRNA levels (P < 0.05 in each case). OARSI scores were also positively correlated with GLI1 (r = 0. 646), PTCH1 (r = 0. 518), and HHIP (r = 0.762) mRNA levels (P < 0.01 in each case). Cumulatively our findings indicate that Indian HH signaling is increased in OA and is perhaps a key component in OA pathogenesis and progression.

  8. Indian Hedgehog signaling pathway members are associated with magnetic resonance imaging manifestations and pathological scores in lumbar facet joint osteoarthritis.

    PubMed

    Shuang, Feng; Zhou, Ying; Hou, Shu-Xun; Zhu, Jia-Liang; Liu, Yan; Zhang, Chun-Li; Tang, Jia-Guang

    2015-01-01

    Indian Hedgehog (HH) has been shown to be involved in osteoarthritis (OA) in articular joints, where there is evidence that Indian HH blockade could ameliorate OA. It seems to play a prominent role in development of the intervertebral disc (IVD) and in postnatal maintenance. There is little work on IHH in the IVD. Hence the aim of the current study was to investigate the role of Indian Hedgehog in the pathology of facet joint (FJ) OA. 24 patients diagnosed with lumbar intervertebral disk herniation or degenerative spinal stenosis were included. Preoperative magnetic resonance imaging (MRI) and Osteoarthritis Research Society International (OARSI) histopathology grading system was correlated to the mRNA levels of GLI1, PTCH1, and HHIP in the FJs. The Weishaupt grading and OARSI scores showed high positive correlation (r = 0.894) (P < 0.01). MRI Weishaupt grades showed positive correlation with GLI1 (r = 0.491), PTCH1 (r = 0.444), and HHIP (r = 0.654) mRNA levels (P < 0.05 in each case). OARSI scores were also positively correlated with GLI1 (r = 0. 646), PTCH1 (r = 0. 518), and HHIP (r = 0.762) mRNA levels (P < 0.01 in each case). Cumulatively our findings indicate that Indian HH signaling is increased in OA and is perhaps a key component in OA pathogenesis and progression. PMID:25992955

  9. Indian Hedgehog signaling pathway members are associated with magnetic resonance imaging manifestations and pathological scores in lumbar facet joint osteoarthritis

    PubMed Central

    Shuang, Feng; Zhou, Ying; Hou, Shu-Xun; Zhu, Jia-Liang; Liu, Yan; Zhang, Chun-Li; Tang, Jia-Guang

    2015-01-01

    Indian Hedgehog (HH) has been shown to be involved in osteoarthritis (OA) in articular joints, where there is evidence that Indian HH blockade could ameliorate OA. It seems to play a prominent role in development of the intervertebral disc (IVD) and in postnatal maintenance. There is little work on IHH in the IVD. Hence the aim of the current study was to investigate the role of Indian Hedgehog in the pathology of facet joint (FJ) OA. 24 patients diagnosed with lumbar intervertebral disk herniation or degenerative spinal stenosis were included. Preoperative magnetic resonance imaging (MRI) and Osteoarthritis Research Society International (OARSI) histopathology grading system was correlated to the mRNA levels of GLI1, PTCH1, and HHIP in the FJs. The Weishaupt grading and OARSI scores showed high positive correlation (r = 0.894) (P < 0.01). MRI Weishaupt grades showed positive correlation with GLI1 (r = 0.491), PTCH1 (r = 0.444), and HHIP (r = 0.654) mRNA levels (P < 0.05 in each case). OARSI scores were also positively correlated with GLI1 (r = 0. 646), PTCH1 (r = 0. 518), and HHIP (r = 0.762) mRNA levels (P < 0.01 in each case). Cumulatively our findings indicate that Indian HH signaling is increased in OA and is perhaps a key component in OA pathogenesis and progression. PMID:25992955

  10. Development of an Experimental Animal Model for Lower Back Pain by Percutaneous Injury-Induced Lumbar Facet Joint Osteoarthritis.

    PubMed

    Kim, Jae-Sung; Ahmadinia, Kasra; Li, Xin; Hamilton, John L; Andrews, Steven; Haralampus, Chris A; Xiao, Guozhi; Sohn, Hong-Moon; You, Jae-Won; Seo, Yo-Seob; Stein, Gary S; Van Wijnen, Andre J; Kim, Su-Gwan; Im, Hee-Jeong

    2015-11-01

    We report generation and characterization of pain-related behavior in a minimally invasive facet joint degeneration (FJD) animal model in rats. FJD was produced by a non-open percutaneous puncture-induced injury on the right lumbar FJs at three consecutive levels. Pressure hyperalgesia in the lower back was assessed by measuring the vocalization response to pressure from a force transducer. After hyperalgesia was established, pathological changes in lumbar FJs and alterations of intervertebral foramen size were assessed by histological and imaging analyses. To investigate treatment options for lumber FJ osteoarthritis-induced pain, animals with established hyperalgesia were administered with analgesic drugs, such as morphine, a selective COX-2 inhibitor, a non-steroidal anti-inflammatory drug (NSAID) (ketorolac), or pregabalin. Effects were assessed by behavioral pain responses. One week after percutaneous puncture-induced injury of the lumbar FJs, ipsilateral primary pressure hyperalgesia developed and was maintained for at least 12 weeks without foraminal stenosis. Animals showed decreased spontaneous activity, but no secondary hyperalgesia in the hind paws. Histopathological and microfocus X-ray computed tomography analyses demonstrated that the percutaneous puncture injury resulted in osteoarthritis-like structural changes in the FJs cartilage and subchondral bone. Pressure hyperalgesia was completely reversed by morphine. The administration of celecoxib produced moderate pain reduction with no statistical significance while the administration of ketorolac and pregabalin produced no analgesic effect on FJ osteoarthritis-induced back pain. Our animal model of non-open percutanous puncture-induced injury of the lumbar FJs in rats shows similar characteristics of low back pain produced by human facet arthropathy. PMID:25858171

  11. Comparison of human lumbar facet joint capsule strains during simulated high-velocity, low-amplitude spinal manipulation versus physiological motions

    PubMed Central

    Ianuzzi, Allyson; Khalsa, Partap S.

    2005-01-01

    BACKGROUND CONTEXT Spinal manipulation (SM) is a n effective treatment for low back pain (LBP), and it has been theorized that SM induces a beneficial neurophysiological effect by stimulating mechanically sensitive neurons in the lumbar facet joint capsule (FJC). PURPOSE The purpose of this study was to determine whether human lumbar FJC strains during simulated SM were different from those that occur during physiological motions. STUDY DESIGN/SETTING Lumbar FJC strains were measured in human cadaveric spine specimens during physiological motions and simulated SM in a laboratory setting. METHODS Specimens were tested during displacement-controlled physiological motions of flexion, extension, lateral bending, and axial rotations. SM was simulated using combinations of manipulation site (L3, L4, and L5), impulse speed (5, 20, and 50 mm/s), and pre-torque magnitude (applied at T12 to simulate patient position; 0, 5, 10 Nm). FJC strains and vertebral motions (using six degrees of freedom) were measured during both loading protocols. RESULTS During SM, the applied loads were within the range measured during SM in vivo. Vertebral translations occurred primarily in the direction of the applied load, and were similar in magnitude regardless of manipulation site. Vertebral rotations and FJC strain magnitudes during SM were within the range that occurred during physiological motions. At a given FJC, manipulations delivered distally induced capsule strains similar in magnitude to those that occurred when the manipulation was applied proximally. CONCLUSIONS FJC strain magnitudes during SM were within the physiological range, suggesting that SM is biomechanically safe. Successful treatment of patients with LBP using SM may not require precise segmental specificity, because the strain magnitudes at a given FJC during SM do not depend upon manipulation site. PMID:15863084

  12. Differences Regarding Branded HA in Italy, Part 2: Data from Clinical Studies on Knee, Hip, Shoulder, Ankle, Temporomandibular Joint, Vertebral Facets, and Carpometacarpal Joint

    PubMed Central

    Migliore, A.; Bizzi, E.; De Lucia, O.; Delle Sedie, A.; Tropea, S.; Bentivegna, M.; Mahmoud, A.; Foti, C.

    2016-01-01

    OBJECTIVES The aim of the current study is to collect scientific data on all branded hyaluronic acid (HA) products in Italy that are in use for intra-articular (IA) injection in osteoarthritis (OA) compared with that reported in the leaflet. METHODS An extensive literature research was performed for all articles reporting data on the IA use of HA in OA. Selected studies were taken into consideration only if they are related to products based on HAs that are currently marketed in Italy with the specific joint indication for IA use in patients affected by OA. RESULTS Sixty-two HA products are marketed in Italy: 30 products are indicated for the knee but only 8 were proved with some efficacy; 9 products were effective for the hip but only 6 had hip indication; 7 products proved to be effective for the shoulder but only 3 had the indication; 5 products proved effective for the ankle but only one had the indication; 6 products were effective for the temporomandibular joint but only 2 had the indication; only 2 proved effective for vertebral facet joints but only 1 had the indication; and 5 products proved effective for the carpometacarpal joint but only 2 had the indication. CONCLUSIONS There are only a few products with some evidences, while the majority of products remain without proof. Clinicians and regulators should request postmarketing studies from pharmaceuticals to corroborate with that reported in the leaflet and to gather more data, allowing the clinicians to choose the adequate product for the patient. PMID:27279754

  13. Cervical Facet Joint Infection and Associated Epidural Abscess with Streptococcus intermedius from a Dental Infection Origin A Case Report and Review.

    PubMed

    Kaye, Ian David; Protopsaltis, Themistocles S

    2016-09-01

    Pyogenic cervical facet joint infections are rare and such infections from a dental origin are even less common. Of these few cases, none have described infection with Streptococcus intermedius as the pathogen. A 65-year-old orthopaedic surgeon complained of fevers, right-sided radiating neck pain, stiffness, swelling, erythema, and right upper extremity weakness one month after he had broken a crown over his right mandibular premolar, a continued source of pain. Imaging of the cervical spine showed a right C4-C5 facet inflammatory arthropathy and a small epidural abscess that was cultured and initially treated with intravenous antibiotics. The oral maxillofacial surgery team performed an extraction of the infected, symptomatic tooth. For continued right upper extremity weakness, the patient underwent C4-C5 laminoforaminotomy and irrigation and debridement of the right C4-C5 facet joint. After 6 weeks of intravenous antibiotics, the patient's infectious and inflammatory markers had normalized. By 4 months, he had regained full strength at his upper extremity and a painless and full range of motion of his cervical spine.Pyogenic cervical facet joint infection is very rare and potentially dangerous. A high clinical suspicion and appropriate imaging, including magnetic resonance imaging, are important for correct diagnosis. Prompt medical and surgical treatment may avert complications, and although the patient presented made a complete recovery, patients may be left with neurological compromise. PMID:27620549

  14. Shoulder joint loading and posture during medicine cart pushing task.

    PubMed

    Xu, Xu; Lin, Jia-Hua; Boyer, Jon

    2013-01-01

    Excessive physical loads and awkward shoulder postures during pushing and pulling are risk factors for shoulder pain. Pushing a medicine cart is a major component of a work shift for nurses and medical assistants in hospitals and other health care facilities. A laboratory experiment was conducted to examine the effects of common factors (e.g., lane congestion, cart load stability, floor surface friction) on shoulder joint moment and shoulder elevation angle of participants during cart pushing. Participants pushed a medicine cart on straight tracks and turning around right-angle corners. Peak shoulder joint moments reached 25.1 Nm, 20.3 Nm, and 26.8 Nm for initial, transition, and turning phases of the pushing tasks, indicating that shoulder joint loading while pushing a medical cart is comparable to levels previously reported from heavy manual activities encountered in industry (e.g., garbage collection). Also, except for user experience, all other main study factors, including congestion level, cart load stability, location of transition strip, shoulder tendency, surface friction, and handedness, significantly influenced shoulder joint moment and shoulder elevation angle. The findings provide a better understanding of shoulder exposures associated with medicine cart operations and may be helpful in designing and optimizing the physical environment where medicine carts are used. PMID:23767931

  15. 654 nm broad area lasers for QCW operation with a maximal facet load of 76 mW/μm

    NASA Astrophysics Data System (ADS)

    Sumpf, B.; Pohl, M.; Pittroff, W.; Staske, R.; Erbert, G.; Tränkle, G.

    2013-03-01

    Compared to diode lasers emitting in the near infrared, the development of high power diode lasers in the red spectral range is more challenging due to the applicable compound semiconductors, the limited stability of the laser facets, and the small barrier heights for electrons and holes. For CW applications, their mounting requires excellent heat removal or expansion matched submounts. For QCW operation with small duty cycles and about 2 W per 100 μm stripe width emitter, like for the pumping of Q-switched alexandrite (Cr3+:BeAl2O4) lasers at 654 nm, a compromise is the application of aluminum nitride as heat sink. The presented broad area (BA) lasers are based on a GaInP single quantum well embedded in AlGaInP waveguide layers. The structure provides a vertical far field angle of 31° (FWHM). The material data can be compiled as follows: transparency current density jT = 220 A/cm2, internal efficiency ƞi = 0.83, internal losses αi = 1.0 cm-1. BA lasers with a stripe width of 100 μm and a length of 1.5 mm were fabricated, facet coated including a passivation procedure, and mounted on AlN submounts. In QCW operation (100 μs, 35 Hz) at 15°C, the devices had threshold currents of about 600 mA, slope efficiencies up to 1.3 W/A and conversion efficiencies of 0.36. A maximal output of 6.3 W was measured. At lower temperatures of -10°C the maximal peak power was determined to 7.6 W, i.e. a facet load of 76 mW/μm. The devices showed reliable operation over 1,000 h at a peak power of 2.7 W.

  16. 3D visualization of the lumbar facet joint after degeneration using propagation phase contrast micro-tomography

    PubMed Central

    Cao, Yong; Zhang, Yi; Yin, Xianzheng; Lu, Hongbin; Hu, Jianzhong; Duan, Chunyue

    2016-01-01

    Lumbar facet joint (LFJ) degeneration is believed to be an important cause of low back pain (LBP). Identifying the morphological changes of the LFJ in the degeneration process at a high-resolution level could be meaningful for our better understanding of the possible mechanisms underlying this process. In the present study, we determined the 3D morphology of the LFJ using propagation phase contrast micro-tomography (PPCT) in rats to assess the subtle changes that occur during the degeneration process. PPCT provides vivid 3D images of micromorphological changes in the LFJ during its degeneration process, and the changes in the subchondral bone occurred earlier than in the cartilage during the early stage of degeneration of the LFJ. The delineation of this alteration was similar to that with the histological method. Our findings demonstrated that PPCT could serve as a valuable tool for 3D visualization of the morphology of the LFJ by providing comprehensive information about the cartilage and the underlying subchondral bone and their changes during degeneration processes. It might also have great potential for providing effective diagnostic tools to track changes in the cartilage and to evaluate the effects of therapeutic interventions for LFJ degeneration in preclinical studies. PMID:26907889

  17. Early osteoarthritis of the trapeziometacarpal joint is not associated with joint instability during typical isometric loading.

    PubMed

    Halilaj, Eni; Moore, Douglas C; Patel, Tarpit K; Ladd, Amy L; Weiss, Arnold-Peter C; Crisco, Joseph J

    2015-11-01

    The saddle-shaped trapeziometacarpal (TMC) joint contributes importantly to the function of the human thumb. A balance between mobility and stability is essential in this joint, which experiences high loads and is prone to osteoarthritis (OA). Since instability is considered a risk factor for TMC OA, we assessed TMC joint instability during the execution of three isometric functional tasks (key pinch, jar grasp, and jar twist) in 76 patients with early TMC OA and 44 asymptomatic controls. Computed tomography images were acquired while subjects held their hands relaxed and while they applied 80% of their maximum effort for each task. Six degree-of-freedom rigid body kinematics of the metacarpal with respect to the trapezium from the unloaded to the loaded task positions were computed in terms of a TMC joint coordinate system. Joint instability was expressed as a function of the metacarpal translation and the applied force. We found that the TMC joint was more unstable during a key pinch task than during a jar grasp or a jar twist task. Sex, age, and early OA did not have an effect on TMC joint instability, suggesting that instability during these three tasks is not a predisposing factor in TMC OA. PMID:25941135

  18. Shear fracture of jointed steel plates of bolted joints under impact load

    NASA Astrophysics Data System (ADS)

    Daimaruya, M.; Fujiki, H.; Ambarita, H.; Kobayashi, H.; Shin, H.-S.

    2013-07-01

    The present study is concerned with the development of a fracture criterion for the impact fracture of jointed steel plates of bolted joints used in a car body, which contributes to crash simulations by CAE. We focus our attention on the shear fracture of the jointed steel plates of lap-bolted joints in the suspension of a car under impact load. Members of lap-bolted joints are modelled as a pair of steel plates connected by a bolt. One of the plates is a specimen subjected to plastic deformation and fracture and the other is a jig subjected to elastic deformation only. Three kinds of steel plate specimens are examined, i.e., a common steel plate with a tensile strength of 270 MPa and high tensile strength steel plates of 440 and 590 MPa used for cars. The impact shear test was performed using the split Hopkinson bar technique for tension impact, together with the static test using a universal testing machine INSTRON 5586. The behaviour of the shear stress and deformation up to rupture taking place in the joint was discussed. The obtained results suggest that a stress-based fracture criterion may be developed for the impact fracture of jointed steel plates of a lap-bolted joint.

  19. Isolated septic facet joint arthritis as a rare cause of acute and chronic low back pain – a case report and literature review

    PubMed Central

    Klekot, Dominika; Zimny, Anna; Czapiga, Bogdan; Sąsiadek, Marek

    2012-01-01

    Summary Background: The most common cause of low back pain is degenerative disease of the intervertebral disc and other structures of the lumbar spine. However, in some cases other less frequent causes of such pain can be seen, for example septic facet joint arthritis. Until now, only 40 cases of such inflammatory changes within the spine have been reported in the literature. The disease is probably underestimated due to improper diagnostic pathway. Case Report: The authors describe a case of a 53-year-old woman who was repeatedly hospitalized during a five-month period because of an acute, severe low back pain, with sphincter dysfunction, partially resembling sciatic symptoms. Physical examinations revealed also focal tenderness in the area of the lumbar spine. Inflammatory markers (ESR – erythrocyte sedimentation rate, CRP – C-reactive protein) were elevated. Conservative analgetic treatment brought only partial and temporary relief of the pain and symptoms. The final accurate diagnosis of isolated septic facet joint arthritis at the level of L5/S1 was established after several months from the onset of the first symptoms, after performing various imaging examinations, including bone scintigraphy as well as CT and MRI of the lumbosacral spine. The patient fully recovered after antibiotic therapy and surgery, which was proven in several follow-up examinations showing no relevant pathology of the lumbar spine. The authors broadly describe the etiology and clinical symptoms of the septic facet joint arthritis as well as the significant role of imaging methods, especially MRI, in diagnostic process. The authors also discuss currently available treatment options, both conservative and surgical. Conclusions: The diagnostic procedure of septic facet joint arthritis requires several steps to be taken. Establishing a correct diagnosis may be difficult, that is why it is important to remember about rare causes of low back pain and to perform detailed physical

  20. A New CT Method for Assessing 3D Movements in Lumbar Facet Joints and Vertebrae in Patients before and after TDR

    PubMed Central

    Svedmark, Per; Berg, Svante; Noz, Marilyn E.; Maguire, Gerald Q.; Zeleznik, Michael P.; Weidenhielm, Lars; Nemeth, Gunnar; Olivecrona, Henrik

    2015-01-01

    This study describes a 3D-CT method for analyzing facet joint motion and vertebral rotation in the lumbar spine after TDR. Ten patients were examined before and then three years after surgery, each time with two CT scans: provoked flexion and provoked extension. After 3D registration, the facet joint 3D translation and segmental vertebral 3D rotation were analyzed at the operated level (L5-S1) and adjacent level (L4-L5). Pain was evaluated using VAS. The median (±SD) 3D movement in the operated level for the left facet joint was 3.2 mm (±1.9 mm) before and 3.5 mm (±1.7 mm) after surgery and for the right facet joint was 3.0 mm (±1.0 mm) before and 3.6 mm (±1.4 mm) after surgery. The median vertebral rotation in the sagittal plane at the operated level was 5.4° (±2.3°) before surgery and 6.8° (±1.7°) after surgery and in the adjacent level was 7.7° (±4.0°) before and 9.2° (±2.7°) after surgery. The median VAS was reduced from 6 (range 5–8) to 3 (range 2–8) in extension and from 4 (range 2–6) to 2 (range 1–3) in flexion. PMID:26587533

  1. Load distributions in photoeleastic bolted-joint models

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.; Liu, D.

    1982-01-01

    An attempt is made to study the stresses in multiple-bolt connectors, focusing on the stress distribution in a two-pin connector, the two pins being in line and in parallel with the direction of the applied load. The photoelastic modeling approach with two-dimensional transmission photoelasticity is used. The joint models and model fringe patterns are discussed, with special attention given to the existence of a photoelastic isotropic point and to the separation of stresses.

  2. Enhanced visible-light-driven photocatalytic H2-production activity of CdS-loaded TiO2 microspheres with exposed (001) facets

    NASA Astrophysics Data System (ADS)

    Gao, Bifen; Yuan, Xia; Lu, Penghui; Lin, Bizhou; Chen, Yilin

    2015-12-01

    CdS-loaded TiO2 microspheres with highly exposed (001) facets were prepared by hydrothermal treatment of a TiF4-HCl-H2O mixed solution followed by a chemical bath deposition of CdS onto TiO2 microspheres. The crystal structure, surficial micro-structure and photo-absorption property of the samples were characterized by XRD, FE-SEM, TEM and UV-vis diffuse reflectance spectroscopy, etc. The as-prepared samples exhibited superior visible-light-driven photocatalytic H2-production activity from lactic acid aqueous solution in comparison with CdS-sensitized TiO2 nanoparticles, whose surface was dominated by (101) facets. Photoelectrochemical measurement confirmed that (001) facet is beneficial for the transfer of photo-generated electron from CdS to TiO2 microsphere, which led to the unexpected high photocatalytic activity of CdS-loaded TiO2 microspheres.

  3. Finite Element Analysis of Sacroiliac Joint Fixation under Compression Loads

    PubMed Central

    Bruna-Rosso, Claire; Arnoux, Pierre-Jean; Bianco, Rohan-Jean; Godio-Raboutet, Yves; Fradet, Léo

    2016-01-01

    Background Sacroiliac joint (SIJ) is a known chronic pain-generator. The last resort of treatment is the arthrodesis. Different implants allow fixation of the joint, but to date there is no tool to analyze their influence on the SIJ biomechanics under physiological loads. The objective was to develop a computational model to biomechanically analyze different parameters of the stable SIJ fixation instrumentation. Methods A comprehensive finite element model (FEM) of the pelvis was built with detailed SIJ representation. Bone and sacroiliac joint ligament material properties were calibrated against experimentally acquired load-displacement data of the SIJ. Model evaluation was performed with experimental load-displacement measurements of instrumented cadaveric SIJ. Then six fixation scenarios with one or two implants on one side with two different trajectories (proximal, distal) were simulated and assessed with the FEM under vertical compression loads. Results The simulated S1 endplate displacement reduction achieved with the fixation devices was within 3% of the experimentally measured data. Under compression loads, the uninstrumented sacrum exhibited mainly a rotation motion (nutation) of 1.38° and 2.80° respectively at 600 N and 1000 N, with a combined relative translation (0.3 mm). The instrumentation with one screw reduced the local displacement within the SIJ by up to 62.5% for the proximal trajectory vs. 15.6% for the distal trajectory. Adding a second implant had no significant additional effect. Conclusion A comprehensive finite element model was developed to assess the biomechanics of SIJ fixation. SIJ devices enable to reduce the motion, mainly rotational, between the sacrum and ilium. Positioning the implant farther from the SIJ instantaneous rotation center was an important factor to reduce the intra-articular displacement. Clinical relevance Knowledge provided by this biomechanical study enables improvement of SIJ fixation through optimal implant

  4. Solid Rocket Booster Hydraulic Pump Port Cap Joint Load Testing

    NASA Technical Reports Server (NTRS)

    Gamwell, W. R.; Murphy, N. C.

    2004-01-01

    The solid rocket booster uses hydraulic pumps fabricated from cast C355 aluminum alloy, with 17-4 PH stainless steel pump port caps. Corrosion-resistant steel, MS51830 CA204L self-locking screw thread inserts are installed into C355 pump housings, with A286 stainless steel fasteners installed into the insert to secure the pump port cap to the housing. In the past, pump port cap fasteners were installed to a torque of 33 Nm (300 in-lb). However, the structural analyses used a significantly higher nut factor than indicated during tests conducted by Boeing Space Systems. When the torque values were reassessed using Boeing's nut factor, the fastener preload had a factor of safety of less than 1, with potential for overloading the joint. This paper describes how behavior was determined for a preloaded joint with a steel bolt threaded into steel inserts in aluminum parts. Finite element models were compared with test results. For all initial bolt preloads, bolt loads increased as external applied loads increased. For higher initial bolt preloads, less load was transferred into the bolt, due to external applied loading. Lower torque limits were established for pump port cap fasteners and additional limits were placed on insert axial deformation under operating conditions after seating the insert with an initial preload.

  5. Prediction and Validation of Load-Dependent Behavior of the Tibiofemoral and Patellofemoral Joints During Movement.

    PubMed

    Lenhart, Rachel L; Kaiser, Jarred; Smith, Colin R; Thelen, Darryl G

    2015-11-01

    The study objective was to construct and validate a subject-specific knee model that can simulate full six degree of freedom tibiofemoral and patellofemoral joint behavior in the context of full body movement. Segmented MR images were used to reconstruct the geometry of 14 ligament bundles and articular cartilage surfaces. The knee was incorporated into a lower extremity musculoskeletal model, which was then used to simulate laxity tests, passive knee flexion, active knee flexion, and human walking. Simulated passive and active knee kinematics were shown to be consistent with subject-specific measures obtained via dynamic MRI. Anterior tibial translation and internal tibial rotation exhibited the greatest variability when uncertainties in ligament properties were considered. When used to simulate walking, the model predicted knee kinematic patterns that differed substantially from passive joint behavior. Predictions of ean knee cartilage contact pressures during normal gait reached 6.2 and 2.8 Pa on the medial tibial plateau and patellar facets, respectively. Thus, the dynamic modeling framework can be used to simulate the interaction of soft tissue loads and cartilage contact during locomotion activities, and therefore provides a basis to simulate the effects of soft tissue injury and surgical treatment on functional knee mechanics. PMID:25917122

  6. Effects of Enzymatic Degradation after Loading in Temporomandibular Joint

    PubMed Central

    Asakawa-Tanne, Y.; Su, S.; Kunimatsu, R.; Hirose, N.; Mitsuyoshi, T.; Okamoto, Y.; Tanaka, E.; Tanne, K.

    2015-01-01

    Synovial fluid of the joint decreases friction between the cartilage surfaces and reduces cartilage wear during articulation. Characteristic changes of synovial fluid have been shown in patients with osteoarthritis (OA) in the temporomandibular joint (TMJ). OA is generally considered to be induced by excessive mechanical stress. However, whether the changes in synovial fluid precede the mechanical overloading or vice versa remains unclear. In the present study, our purpose was to examine if the breakdown of joint lubrication affects the frictional properties of mandibular condylar cartilage and leads to subsequent degenerative changes in TMJ. We measured the frictional coefficient in porcine TMJ by a pendulum device after digestion with hyaluronidase (HAase) or trypsin. Gene expressions of interleukin-1β (IL-1β), cyclooxygenase-2 (COX-2), matrix metalloproteinases (MMPs), type II collagen, and histology were examined after prolonged cyclic loading by an active pendulum system. The results showed that the frictional coefficient increased significantly after HAase (35%) or trypsin (74%) treatment. Gene expression of IL-1β, COX-2, and MMPs-1, -3, and -9 increased significantly in enzyme-treated TMJs after cyclic loading. The increase in the trypsin-treated group was greater than that in the HAase-treated group. Type II collagen expression was reduced in both enzyme-treated groups. Histology revealed surface fibrillation and increased MMP-1 in the trypsin-treated group, as well as increased IL-1β in both enzyme-treated groups after cyclic loading. The findings demonstrated that the compromised lubrication in TMJ is associated with altered frictional properties and surface wear of condylar cartilage, accompanied by release of pro-inflammatory and matrix degradation mediators under mechanical loading. PMID:25503611

  7. Modeling of Anisotropic Rock Joints Under Cyclic Loading (Invited)

    NASA Astrophysics Data System (ADS)

    White, J. A.

    2013-12-01

    This work describes a constitutive framework for modeling the behavior of rough joints under cyclic loading. Particular attention is paid to the intrinsic links between dilatancy, surface degradation, and mobilized shear strength. The framework also accounts for the important effect of shear-induced anisotropy. Both the governing formulation and an algorithm for implicit numerical integration are presented. While the proposed methods are general, we also postulate a specific model that is compared with experimental data. It employs relatively few free parameters, but shows good agreement with laboratory tests.

  8. Development of fracture facets from a crack loaded in mode I+III: Solution and application of a model 2D problem

    NASA Astrophysics Data System (ADS)

    Leblond, Jean-Baptiste; Frelat, Joël

    2014-03-01

    It is experimentally well-known that a crack loaded in mode I+III propagates through formation of discrete fracture facets inclined at a certain tilt angle on the original crack plane, depending on the ratio of the mode III to mode I initial stress intensity factors. Pollard et al. (1982) have proposed to calculate this angle by considering the tractions on all possible future infinitesimal facets and assuming shear tractions to be zero on that which will actually develop. In this paper we consider the opposite case of well-developed facets; the stress field near the lateral fronts of such facets becomes independent of the initial crack and essentially 2D in a plane perpendicular to the main direction of crack propagation. To determine this stress field, we solve the model 2D problem of an infinite plate containing an infinite periodic array of cracks inclined at some angle on a straight line, and loaded through uniform stresses at infinity. This is done first analytically, for small values of this angle, by combining Muskhelishvili's (1953) formalism and a first-order perturbation procedure. The formulae found for the 2D stress intensity factors are then extended in an approximate way to larger angles by using another reference solution, and finally assessed through comparison with some finite element results. To finally illustrate the possible future application of these formulae to the prediction of the stationary tilt angle, we introduce the tentative assumption that the 2D mode II stress intensity factor is zero on the lateral fronts of the facets. An approximate formula providing the tilt angle as a function of the ratio of the mode III to mode I stress intensity factors of the initial crack is deduced from there. This formula, which slightly depends on the type of loading imposed, predicts somewhat smaller angles than that of Pollard et al. (1982).

  9. Critical Values of Facet Joint Angulation and Tropism in the Development of Lumbar Degenerative Spondylolisthesis: An International, Large-Scale Multicenter Study by the AOSpine Asia Pacific Research Collaboration Consortium

    PubMed Central

    Samartzis, Dino; Cheung, Jason Pui Yin; Rajasekaran, Shanmuganathan; Kawaguchi, Yoshiharu; Acharya, Shankar; Kawakami, Mamoru; Satoh, Shigenobu; Chen, Wen-Jer; Park, Chun-Kun; Lee, Chong-Suh; Foocharoen, Thanit; Nagashima, Hideki; Kuh, Sunguk; Zheng, Zhaomin; Condor, Richard; Ito, Manabu; Iwasaki, Motoki; Jeong, Je Hoon; Luk, Keith D. K.; Prijambodo, Bambang; Rege, Amol; Jahng, Tae-Ahn; Luo, Zhuojing; Tassanawipas, Warat; Acharya, Narayana; Pokharel, Rohit; Shen, Yong; Ito, Takui; Zhang, Zhihai; Aithala P, Janardhana; Kumar, Gomatam Vijay; Jabir, Rahyussalim Ahmad; Basu, Saumyajit; Li, Baojun; Moudgil, Vishal; Goss, Ben; Sham, Phoebe; Williams, Richard

    2015-01-01

    Study Design  An international, multicenter cross-sectional image-based study performed in 33 institutions in the Asia Pacific region. Objective  The study addressed the role of facet joint angulation and tropism in relation to L4–L5 degenerative spondylolisthesis (DS). Methods  The study included 349 patients (63% females; mean age: 61.8 years) with single-level DS; 82 had no L4–L5 DS (group A) and 267 had L4–L5 DS (group B). Axial computed tomography and magnetic resonance imaging were utilized to assess facet joint angulations and tropism (i.e., asymmetry between facet joint angulations) between groups. Results  There was a statistically significant difference between group A (left mean: 46.1 degrees; right mean: 48.2 degrees) and group B (left mean: 55.4 degrees; right mean: 57.5 degrees) in relation to bilateral L4–L5 facet joint angulations (p < 0.001). The mean bilateral angulation difference was 7.4 and 9.6 degrees in groups A and B, respectively (p = 0.025). A critical value of 58 degrees or greater significantly increased the likelihood of DS if unilateral (adjusted OR: 2.5; 95% CI: 1.2 to 5.5; p = 0.021) or bilateral facets (adjusted OR: 5.9; 95% CI: 2.7 to 13.2; p < 0.001) were involved. Facet joint tropism was found to be relevant between 16 and 24 degrees angulation difference (adjusted OR: 5.6; 95% CI: 1.2 to 26.1; p = 0.027). Conclusions  In one of the largest studies assessing facet joint orientation in patients with DS, greater sagittal facet joint angulation was associated with L4-L5 DS, with a critical value of 58 degrees or greater increasing the likelihood of the condition for unilateral and bilateral facet joint involvement. Specific facet joint tropism categories were noted to be associated with DS. PMID:27433424

  10. Reduction of radiation dose during facet joint injection using the new image guidance system SabreSource™: a prospective study in 60 patients

    PubMed Central

    Proschek, Dirk; Kafchitsas, K.; Rauschmann, M. A.; Kurth, A. A.; Vogl, T. J.

    2008-01-01

    Interventional procedures are associated with high radiation doses for both patients and surgeons. To reduce the risk from ionizing radiation, it is essential to minimize radiation dose. This prospective study was performed to evaluate the effectiveness in reducing radiation dose during facet joint injection in the lumbar spine and to evaluate the feasibility and possibilities of the new real time image guidance system SabreSource™. A total of 60 patients, treated with a standardized injection therapy of the facet joints L4–L5 or L5–S1, were included in this study. A total of 30 patients were treated by fluoroscopy guidance alone, the following 30 patients were treated using the new SabreSource™ system. Thus a total of 120 injections to the facet joints were performed. Pain, according to the visual analogue scale (VAS), was documented before and 6 h after the intervention. Radiation dose, time of radiation and the number of exposures needed to place the needle were recorded. No significant differences concerning age (mean age 60.5 years, range 51–69), body mass index (mean BMI 26.2, range 22.2–29.9) and preoperative pain (VAS 7.9, range 6–10) were found between the two groups. There was no difference in pain reduction between the two groups (60 vs. 61.5%; P = 0.001) but the radiation dose was significantly smaller with the new SabreSource™ system (reduction of radiation dose 32.7%, P = 0.01; reduction of mean entrance surface dose 32.3%, P = 0.01). The SabreSource™ System significantly reduced the radiation dose received during the injection therapy of the lumbar facet joints. With minimal effort for the setup at the beginning of a session, the system is easy to handle and can be helpful for other injection therapies (e.g. nerve root block therapies). PMID:19082641

  11. Loading configurations and driving mechanisms for joints based on the Griffith energy-balance concept

    NASA Astrophysics Data System (ADS)

    Engelder, Terry; Fischer, Mark P.

    1996-05-01

    Using the Griffith energy-balance concept to model joint propagation in the brittle crust, two laboratory loading configurations serve as appropriate analogs for in situ conditions: the dead-weight load and the fixed-grips load. The distinction between these loading configurations is based largely on whether or not a loaded boundary moves as a joint grows. During displacement of a loaded boundary, the energy necessary for joint propagation comes from work by the dead weight (i.e., a remote stress). When the loaded boundary remains stationary, as if held by rigid grips, the energy for joint propagation develops upon release of elastic strain energy within the rock mass. These two generic loading configurations serve as models for four common natural loading configurations: a joint-normal load; a thermoelastic load; a fluid load; and an axial load. Each loading configuration triggers a different joint-driving mechanism, each of which is the release of energy through elastic strain and/or work. The four mechanisms for energy release are joint-normal stretching, elastic contraction, poroelastic contraction under either a constant fluid drive or fluid decompression, and axial shortening, respectively. Geological circumstances favoring each of the joint-driving mechanisms are as follows. The release of work under joint-normal stretching occurs whenever layer-parallel extension keeps pace with slow or subcritical joint propagation. Under fixed grips, a substantial crack-normal tensile stress can accumulate by thermoelastic contraction until joint propagation is driven by the release of elastic strain energy. Within the Earth the rate of joint propagation dictates which of these two driving mechanisms operates, with faster propagation driven by release of strain energy. Like a dead-weight load acting to separate the joint walls, pore fluid exerts a traction on the interior of some joints. Joint propagation under fluid loading may be driven by a release of elastic strain

  12. An International Multicenter Study Assessing the Role of Ethnicity on Variation of Lumbar Facet Joint Orientation and the Occurrence of Degenerative Spondylolisthesis in Asia Pacific: A Study from the AOSpine Asia Pacific Research Collaboration Consortium

    PubMed Central

    Williams, Richard; Cheung, Jason Pui Yin; Goss, Ben; Rajasekaran, Shanmuganathan; Kawaguchi, Yoshiharu; Acharya, Shankar; Kawakami, Mamoru; Satoh, Shigenobu; Chen, Wen-Jer; Park, Chun-Kun; Lee, Chong-Suh; Foocharoen, Thanit; Nagashima, Hideki; Kuh, Sunguk; Zheng, Zhaomin; Condor, Richard; Ito, Manabu; Iwasaki, Motoki; Jeong, Je Hoon; Luk, Keith D. K.; Prijambodo, Bambang; Rege, Amol; Jahng, Tae-Ahn; Luo, Zhuojing; Tassanawipas, Warat; Acharya, Narayana; Pokharel, Rohit; Shen, Yong; Ito, Takui; Zhang, Zhihai; Aithala P, Janardhana; Kumar, Gomatam Vijay; Jabir, Rahyussalim Ahmad; Basu, Saumyajit; Li, Baojun; Moudgil, Vishal; Sham, Phoebe; Samartzis, Dino

    2015-01-01

    Study Design A multinational, multiethnic, cross-sectional image-based study was performed in 33 institutions, representing 10 countries, which were part of the AOSpine Asia Pacific Research Collaboration Consortium. Objective Lumbar facet joint orientation has been reported to be associated with the development of degenerative spondylolisthesis (DS). The role of ethnicity regarding facet joint orientation remains uncertain. As such, the following study was performed across a wide-ranging population base to assess the role of ethnicity in facet joint orientation in patients with DS in the Asia Pacific region. Methods Lateral standing X-rays and axial magnetic resonance imaging scans were obtained for patients with lumbar DS. The DS parameters and facet joint angulations were assessed from L3–S1. Sex, age, body mass index (BMI), and ethnicity were also noted. Results The study included 371 patients with known ethnic origin (mean age: 62.0 years; 64% males, 36% females). The mean BMI was 25.6 kg/m2. The level of DS was most prevalent at L4–L5 (74.7%). There were 28.8% Indian, 28.6% Japanese, 18.1% Chinese, 8.6% Korean, 6.5% Thai, 4.9% Caucasian, 2.7% Filipino, and 1.9% Malay patients. Variations in facet joint angulations were noted from L3 to S1 and between patients with and without DS (p < 0.05). No differences were noted with regards to sex and overall BMI to facet joint angulations (p > 0.05); however, increasing age was found to increase the degree of angulation throughout the lumbar spine (p < 0.05). Accounting for age and the presence or absence of DS at each level, no statistically significant differences between ethnicity and degree of facet joint angulations from L3–L5 were noted (p > 0.05). Ethnic variations were noted in non-DS L5–S1 facet joint angulations, predominantly between Caucasian, Chinese, and Indian ethnicities (p < 0.05). Conclusions This study is the first to suggest that ethnicity may not play a role in

  13. An International Multicenter Study Assessing the Role of Ethnicity on Variation of Lumbar Facet Joint Orientation and the Occurrence of Degenerative Spondylolisthesis in Asia Pacific: A Study from the AOSpine Asia Pacific Research Collaboration Consortium.

    PubMed

    Williams, Richard; Cheung, Jason Pui Yin; Goss, Ben; Rajasekaran, Shanmuganathan; Kawaguchi, Yoshiharu; Acharya, Shankar; Kawakami, Mamoru; Satoh, Shigenobu; Chen, Wen-Jer; Park, Chun-Kun; Lee, Chong-Suh; Foocharoen, Thanit; Nagashima, Hideki; Kuh, Sunguk; Zheng, Zhaomin; Condor, Richard; Ito, Manabu; Iwasaki, Motoki; Jeong, Je Hoon; Luk, Keith D K; Prijambodo, Bambang; Rege, Amol; Jahng, Tae-Ahn; Luo, Zhuojing; Tassanawipas, Warat; Acharya, Narayana; Pokharel, Rohit; Shen, Yong; Ito, Takui; Zhang, Zhihai; Aithala P, Janardhana; Kumar, Gomatam Vijay; Jabir, Rahyussalim Ahmad; Basu, Saumyajit; Li, Baojun; Moudgil, Vishal; Sham, Phoebe; Samartzis, Dino

    2016-02-01

    Study Design A multinational, multiethnic, cross-sectional image-based study was performed in 33 institutions, representing 10 countries, which were part of the AOSpine Asia Pacific Research Collaboration Consortium. Objective Lumbar facet joint orientation has been reported to be associated with the development of degenerative spondylolisthesis (DS). The role of ethnicity regarding facet joint orientation remains uncertain. As such, the following study was performed across a wide-ranging population base to assess the role of ethnicity in facet joint orientation in patients with DS in the Asia Pacific region. Methods Lateral standing X-rays and axial magnetic resonance imaging scans were obtained for patients with lumbar DS. The DS parameters and facet joint angulations were assessed from L3-S1. Sex, age, body mass index (BMI), and ethnicity were also noted. Results The study included 371 patients with known ethnic origin (mean age: 62.0 years; 64% males, 36% females). The mean BMI was 25.6 kg/m(2). The level of DS was most prevalent at L4-L5 (74.7%). There were 28.8% Indian, 28.6% Japanese, 18.1% Chinese, 8.6% Korean, 6.5% Thai, 4.9% Caucasian, 2.7% Filipino, and 1.9% Malay patients. Variations in facet joint angulations were noted from L3 to S1 and between patients with and without DS (p < 0.05). No differences were noted with regards to sex and overall BMI to facet joint angulations (p > 0.05); however, increasing age was found to increase the degree of angulation throughout the lumbar spine (p < 0.05). Accounting for age and the presence or absence of DS at each level, no statistically significant differences between ethnicity and degree of facet joint angulations from L3-L5 were noted (p > 0.05). Ethnic variations were noted in non-DS L5-S1 facet joint angulations, predominantly between Caucasian, Chinese, and Indian ethnicities (p < 0.05). Conclusions This study is the first to suggest that ethnicity may not play a role in facet

  14. Interaction of Bearing and Tensile Loads on Creep Properties of Joints

    NASA Technical Reports Server (NTRS)

    Bodine, E G; Carlson, R L; Manning, G K

    1956-01-01

    The interaction of bearing and tensile loads on the creep behavior of joints was studied. A specimen was designed for this study which possessed some of the general features of pin and rivet joint connections and an apparatus was constructed to apply both bearing and tensile loads to the joint model. Deformation measurements were made by use of a photogrid printed on the joint model.

  15. Fluoroscopic cervical epidural injections in chronic axial or disc-related neck pain without disc herniation, facet joint pain, or radiculitis

    PubMed Central

    Manchikanti, Laxmaiah; Cash, Kimberly A; Pampati, Vidyasagar; Malla, Yogesh

    2012-01-01

    Background While chronic neck pain is a common problem in the adult population, with a typical 12-month prevalence of 30%–50%, there is a lack of consensus regarding its causes and treatment. Despite limited evidence, cervical epidural injections are one of the commonly performed nonsurgical interventions in the management of chronic neck pain. Methods A randomized, double-blind, active, controlled trial was conducted to evaluate the effectiveness of cervical interlaminar epidural injections of local anesthetic with or without steroids for the management of chronic neck pain with or without upper extremity pain in patients without disc herniation, radiculitis, or facet joint pain. Results One hundred and twenty patients without disc herniation or radiculitis and negative for facet joint pain by means of controlled diagnostic medial branch blocks were randomly assigned to one of two treatment groups, ie, injection of local anesthetic only (group 1) or local anesthetic mixed with nonparticulate betamethasone (group 2). The primary outcome of significant pain relief and improvement in functional status (≥50%) was demonstrated in 72% of group 1 and 68% of group 2. The overall average number of procedures per year was 3.6 in both groups with an average total relief per year of 37–39 weeks in the successful group over a period of 52 weeks. Conclusion Cervical interlaminar epidural injections of local anesthetic with or without steroids may be effective in patients with chronic function-limiting discogenic or axial pain. PMID:22826642

  16. Ultrasonic measurement and monitoring of loads in bolts used in structural joints

    NASA Astrophysics Data System (ADS)

    Koshti, Ajay M.

    2015-04-01

    The paper is an overview of work by the author in measuring and monitoring loads in bolts using an ultrasonic extensometer. A number of cases of bolted joints are covered. These include, a clamped joint with clearance fit between the bolt and hole, a clamped joint with bolt in an interference fit with the hole, a flanged joint which allows the flange and bolt to bend; and a shear joint in a clevis and tang configuration. These applications were initially developed for measuring and monitoring preload in National Aeronautics and Space Administration (NASA) Space Shuttle Orbiter critical joints but are also applicable for monitoring loads in other critical bolted joints of structures such as transportation bridges and other aerospace structures. The papers cited here explain how to set-up a model to estimate the ultrasonic load factor and accuracy for the ultrasonic preload application in a clamped joint with clearance fit. The ultrasonic preload application for clamped joint with bolt in an interference fit can also be used to measure diametrical interference between the bolt shank and hole, as well as interference pressure on the bolt shank. Results of simulation and experimental data are given to demonstrate use of ultrasonic measurements in a shear joint. A bolt in a flanged joint experiences both tensile and bending loads. This application involves measurement of bending and tensile preload in a bolt. The ultrasonic beam bends due to bending load on the bolt. Results of a numerical technique to compute the trace of ultrasonic ray are presented.

  17. Photonic Waveguide Choke Joint with Non-Absorptive Loading

    NASA Technical Reports Server (NTRS)

    Wollack, Edward J. (Inventor); U-Yen, Kongpop (Inventor); Chuss, David T. (Inventor)

    2016-01-01

    A waveguide choke joint includes a first array of pillars positioned on a substrate, each pillar in the first array of pillars having a first size and configured to receive an input plane wave at a first end of the choke joint. The choke joint has a second end configured to transmit the input plane wave away from the choke joint. The choke joint further includes a second array of pillars positioned on the substrate between the first array of pillars and the second end of the choke joint. Each pillar in the second array of pillars has a second size. The choke joint also has a third array of pillars positioned on the substrate between the second array and the second end of the choke joint. Each pillar in the third array of pillars has a third size.

  18. Biomechanical loading of the shoulder complex and lumbosacral joints during dynamic cart pushing task.

    PubMed

    Nimbarte, Ashish D; Sun, Yun; Jaridi, Majid; Hsiao, Hongwei

    2013-09-01

    The primary objective of this study was to quantify the effect of dynamic cart pushing exertions on the biomechanical loading of shoulder and low back. Ten participants performed cart pushing tasks on flat (0°), 5°, and 10° ramped walkways at 20 kg, 30 kg, and 40 kg weight conditions. An optoelectronic motion capturing system configured with two force plates was used for the kinematic and ground reaction force data collection. The experimental data was modeled using AnyBody modeling system to compute three-dimensional peak reaction forces at the shoulder complex (sternoclavicular, acromioclavicular, and glenohumeral) and low back (lumbosacral) joints. The main effect of walkway gradient and cart weight, and gradient by weight interaction on the biomechanical loading of shoulder complex and low back joints was statistically significant (all p < 0.001). At the lumbosacral joint, negligible loading in the mediolateral direction was observed compared to the anterioposterior and compression directions. Among the shoulder complex joints, the peak reaction forces at the acromioclavicular and glenohumeral joints were comparable and much higher than the sternoclavicular joint. Increased shear loading of the lumbosacral joint, distraction loading of glenohumeral joint and inferosuperior loading of the acromioclavicular joint may contribute to the risk of work-related low back and shoulder musculoskeletal disorder with prolonged and repetitive use of carts. PMID:23566675

  19. Synthesis of Pt-Loaded Self-Interspersed Anatase TiO2 with a Large Fraction of (001) Facets for Efficient Photocatalytic Nitrobenzene Degradation.

    PubMed

    Wang, Wei-Kang; Chen, Jie-Jie; Li, Wen-Wei; Pei, Dan-Ni; Zhang, Xing; Yu, Han-Qing

    2015-09-16

    TiO2 is capable of directly utilizing solar energy for sustainable energy harvest and water purification. Facet-dependent performance of TiO2 has attracted enormous interests due to its tunable photocatalytic activity toward photoredox transformations, but information about the noble-metal-loaded TiO2 for its facet-dependent photocatalytic performance, especially in pollutant degradation systems, is limited. In this work, inspired by our previous theoretical calculations about the roles of the crystal surface in Pt-loaded TiO2 in its enhanced photocatalytic capacity, TiO2 nanocrystals with interspersed polyhedron nanostructures and coexposed (001) and (101) surfaces as a support of Pt nanoparticles are prepared in a simple and relatively green route. Also, their performance for photocatalytic degradation of nitrobenzene (NB), a model organic pollutant, is explored. The experimental results demonstrate that the NB photodegradation and photoconversion efficiencies are significantly enhanced by uniformly loading Pt nanoparticles on the crystal surfaces, but the Pt nanoparticles deposited on only the (101) surface have no contribution to the improved NB photodegradation. Furthermore, the liquid chromatography mass spectrometry results also show that NB photodegradation tends to proceed on the (001) surface of Pt/TiO2 for the generation of nitrophenol intermediates through the photooxidation pathway. This work provides a new route to design and construct advanced photocatalysts toward pollutant photoredox conversions and deepens our fundamental understanding about crystal surface engineering. PMID:26308282

  20. Numerical Modeling of Jointed Rock Under Compressive Loading Using X-ray Computerized Tomography

    NASA Astrophysics Data System (ADS)

    Yu, Qinglei; Yang, Shengqi; Ranjith, P. G.; Zhu, Wancheng; Yang, Tianhong

    2016-03-01

    As jointed rocks consist of joints embedded within intact rock blocks, the presence and geometrical fabric of joints have a great influence on the mechanical behavior of rock. With consideration of the actual spatial shape of joints, a numerical model is proposed to investigate the fracture evolution mechanism of jointed rocks. In the proposed model, computerized tomography (CT) scanning is first used to capture the microstructure of a jointed sandstone specimen, which is artificially fabricated by loading the intact sample until the residual strength, and then digital image processing (DIP) techniques are applied to characterize the geometrical fabric of joints from the CT images. A simple vectorization method is used to convert the microstructure based on a cross-sectional image into a layer of 3-D vectorized microstructure and the overall 3-D model of the jointed sandstone including the real spatial shape of the joints is established by stacking the layers in a specific sequence. The 3-D model is then integrated into a well-established code [three-dimensional Rock Failure Process Analysis, (RFPA3D)]. Using the proposed model, a uniaxial compression test of the jointed sandstone is simulated. The results show that the presence of joints can produce tensile stress zones surrounding them, which result in the fracture of jointed rocks under a relatively small external load. In addition, the spatial shape of the joints has a great influence on the fracture process of jointed rocks.

  1. Low-Friction, High-Stiffness Joint for Uniaxial Load Cell

    NASA Technical Reports Server (NTRS)

    Lewis, James L.; Le, Thang; Carroll, Monty B.

    2007-01-01

    A universal-joint assembly has been devised for transferring axial tension or compression to a load cell. To maximize measurement accuracy, the assembly is required to minimize any moments and non-axial forces on the load cell and to exhibit little or no hysteresis. The requirement to minimize hysteresis translates to a requirement to maximize axial stiffness (including minimizing backlash) and a simultaneous requirement to minimize friction. In practice, these are competing requirements, encountered repeatedly in efforts to design universal joints. Often, universal-joint designs represent compromises between these requirements. The improved universal-joint assembly contains two universal joints, each containing two adjustable pairs of angular-contact ball bearings. One might be tempted to ask why one could not use simple ball-and-socket joints rather than something as complex as universal joints containing adjustable pairs of angularcontact ball bearings. The answer is that ball-and-socket joints do not offer sufficient latitude to trade stiffness versus friction: the inevitable result of an attempt to make such a trade in a ball-and-socket joint is either too much backlash or too much friction. The universal joints are located at opposite ends of an axial subassembly that contains the load cell. The axial subassembly includes an axial shaft, an axial housing, and a fifth adjustable pair of angular-contact ball bearings that allows rotation of the axial housing relative to the shaft. The preload on each pair of angular-contact ball bearings can be adjusted to obtain the required stiffness with minimal friction, tailored for a specific application. The universal joint at each end affords two degrees of freedom, allowing only axial force to reach the load cell regardless of application of moments and non-axial forces. The rotational joint on the axial subassembly affords a fifth degree of freedom, preventing application of a torsion load to the load cell.

  2. Heavily loaded joints for assembling aerobrake support trusses

    NASA Technical Reports Server (NTRS)

    Bandel, Hannskarl; Olsson, Nils; Levintov, Boris

    1990-01-01

    The major emphasis was to develop erectable joints for large aerobrake support trusses. The truss joints must be able to withstand the large forces experienced by the truss during the aero-pass, as well as be easily assembled and disassembled on orbit by astronauts or robots. Other important design considerations include; strength, stiffness, and allowable error in strut length. Six mechanical joint designs, as well as a seventh joint design, where a high strength epoxy is injected to make the connection rigid, are presented.

  3. Antibiotic-loaded bone cement in total joint arthroplasty.

    PubMed

    Soares, Daniel; Leite, Pedro; Barreira, Pedro; Aido, Ricardo; Sousa, Ricardo

    2015-06-01

    Periprosthetic joint infection is a devastating complication after total joint replacement. Prevention is mandatory and systemic antibiotic prophylaxis is nowadays a recognized cornerstone. Further addition of local antibiotics eluting from bone cement is a real possibility but its routine use is controversial. Pros and cons of its routine use in primary and revision total joint arthroplasty will be discussed. Cement spacers carrying high doses of antibiotic(s) are currently accepted during two-stage treatment of infected prosthetic joints. Several issues such as alternatives to classic antibiotics, optimal dosages and others will also be explored. PMID:26280954

  4. Synthesis and photocatalytic properties of Palladium-loaded three dimensional flower-like anatase TiO2 with dominant {001} facets.

    PubMed

    Bai, Xue; Lv, Lingling; Zhang, Xiaoyuan; Hua, Zulin

    2016-04-01

    Palladium-loaded (Pd-loaded) anatase TiO2 with dominant {001} facets used as photocatalysts was prepared by a two-step process. Three dimensional flower-like structures of anatase TiO2 with exposed {001} facets were synthesized by solvothermal method, and then Pd nanoparticles were photodeposited onto the {101} surface of TiO2 by UV reduction. The resulting Pd/TiO2 was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectra. Characterization results indicated that the flower-like structures of anatase TiO2 were assembled by two dimensional nanosheets with a thickness of approximately 10nm and a length of approximately 1.0μm. The Pd/TiO2 nanocomposites with improved visible-light-harvesting capability, high charge-hole mobility, and low electron-hole recombination exhibited improved photocatalytic performance in degrading bisphenol A. This study provided new insights into the fabrication and practical application of high-performance photocatalysts in degrading organic pollutants. PMID:26771748

  5. Moderate Joint Loading Reduces Degenerative Actions of Matrix Metalloproteinases in the Articular Cartilage of Mouse Ulnae

    PubMed Central

    Sun, Hui B.; Zhao, Liming; Tanaka, Shigeo; Yokota, Hiroki

    2015-01-01

    Joint loading is a recently developed loading modality, which can enhance bone formation and accelerate healing of bone fracture. Since mechanical stimulation alters expression of matrix metalloproteinases (MMPs) in chondrocytes, a question addressed herein was, does joint loading alter actions of MMPs in the articular cartilage? We hypothesized that expression and activity of MMPs are regulated in a load–intensity-dependent manner and that moderate load scan downregulates MMPs. To test this hypothesis, a mouse elbow-loading model was employed. In the articular cartilage of an ulna, the mRNA levels of a group of MMPs as well as their degenerative activities were determined. The result revealed that elbow loading altered the expression and activities of MMPs depending on its loading intensity. Collectively, the data in this study indicate that 0.2 and 0.5 N joint loading significantly reduced the expression of multiple MMPs, that is, MMP-1, MMP-3, MMP-8, and MMP-13, and overall activities of collagenases or gelatinases in articular cartilage, while higher loads increased the expression and activity of MMP-1 and MMP-13. Furthermore, moderate loads at 1 N elevated the mRNA level of CBP/p300-interacting transactivator with ED-rich tail 2 (CITED2), but higher loads at 4 N did not induce a detectable amount of CITED2 mRNA. Since CITED2 is known to mediate the downregulation of MMP-1 and MMP-13, the result indicates that joint loading at moderate intensity reduces MMP activities through potential induction of CITED2. MMPs such as MMP-1 and MMP-13 are predominant collagenases in the pathology of osteoarthritis. Therefore, joint loading could offer an interventional regimen for maintenance of joint tissues. PMID:22148954

  6. Increased joint loads during walking--a consequence of pain relief in knee osteoarthritis.

    PubMed

    Henriksen, Marius; Simonsen, Erik B; Alkjaer, Tine; Lund, Hans; Graven-Nielsen, Thomas; Danneskiold-Samsøe, Bente; Bliddal, Henning

    2006-12-01

    Joint pain is a primary symptom in knee osteoarthritis (OA), but the effect of pain and pain relief on the knee joint mechanics of walking is not clear. In this study, the effects of local knee joint analgesia on knee joint loads during walking were studied in a group of knee osteoarthritis patients. A group of healthy subjects was included as a reference group. The joint loads were calculated from standard gait analysis data obtained with standardised walking speed (4 km/h). The gait analyses were performed before and after pain relief by intra-articular injections of 10 mL lidocaine (1%). Pre-injection measurements revealed lower joint loads in the OA group compared to the reference group. Following injections pain during walking decreased significantly and the joint loads increased in the OA group during the late single support phase to a level comparable to the reference group. Although the patients walked with less compressive knee joint forces compared to the reference group, the effects of pain relief may accelerate the degenerative changes. PMID:17011194

  7. Patellofemoral Joint and Achilles Tendon Loads During Overground and Treadmill Running.

    PubMed

    Willy, Richard W; Halsey, Lisa; Hayek, Andrew; Johnson, Holly; Willson, John D

    2016-08-01

    Study Design Level 4, controlled laboratory study. Background Little is known regarding how the potential differences between treadmill and overground running may affect patellofemoral joint and Achilles tendon loading characteristics. Objectives To compare measures of loading of the patellofemoral joint and Achilles tendon across treadmill and overground running in healthy, uninjured runners. Methods Eighteen healthy runners ran at their self-selected speed on an instrumented treadmill and overground, while 3-D running mechanics were sampled. A musculoskeletal model derived peak load, rate of loading, and estimated cumulative load per 1 km of continuous running for the patellofemoral joint and Achilles tendon for each condition. Data were analyzed via paired t tests and Pearson correlations to detect differences and assess relationships, respectively, between the 2 running mediums. Results No differences (P>.05) were found between treadmill and overground running for peak load, rate of loading, or estimated cumulative patellofemoral joint stress per 1 km of continuous running. However, treadmill running resulted in 12.5% greater peak Achilles tendon force (P<.001), 15.6% greater loading rate of Achilles tendon force (P<.001), and 14.2% greater estimated cumulative Achilles tendon force per 1 km of continuous running (P<.001) compared with overground running. There were strong (r>0.70) and moderate agreements (r>0.50) for most patellofemoral joint and Achilles measures, respectively, between treadmill and overground running. Conclusion No differences were observed in loading characteristics to the patellofemoral joint between running mediums; however, treadmill running resulted in greater Achilles tendon loading compared with overground running. Future investigations should examine whether sudden bouts of treadmill running may increase the risk of mechanical overload of the Achilles tendon in runners who habitually train overground. J Orthop Sports Phys Ther 2016

  8. Joint power and kinematics coordination in load carriage running: Implications for performance and injury.

    PubMed

    Liew, Bernard X W; Morris, Susan; Netto, Kevin

    2016-06-01

    Investigating the impact of incremental load magnitude on running joint power and kinematics is important for understanding the energy cost burden and potential injury-causative mechanisms associated with load carriage. It was hypothesized that incremental load magnitude would result in phase-specific, joint power and kinematic changes within the stance phase of running, and that these relationships would vary at different running velocities. Thirty-one participants performed running while carrying three load magnitudes (0%, 10%, 20% body weight), at three velocities (3, 4, 5m/s). Lower limb trajectories and ground reaction forces were captured, and global optimization was used to derive the variables. The relationships between load magnitude and joint power and angle vectors, at each running velocity, were analyzed using Statistical Parametric Mapping Canonical Correlation Analysis. Incremental load magnitude was positively correlated to joint power in the second half of stance. Increasing load magnitude was also positively correlated with alterations in three dimensional ankle angles during mid-stance (4.0 and 5.0m/s), knee angles at mid-stance (at 5.0m/s), and hip angles during toe-off (at all velocities). Post hoc analyses indicated that at faster running velocities (4.0 and 5.0m/s), increasing load magnitude appeared to alter power contribution in a distal-to-proximal (ankle→hip) joint sequence from mid-stance to toe-off. In addition, kinematic changes due to increasing load influenced both sagittal and non-sagittal plane lower limb joint angles. This study provides a list of plausible factors that may influence running energy cost and injury risk during load carriage running. PMID:27264407

  9. Joint Procrustes Analysis for Simultaneous Nonsingular Transformation of Component Score and Loading Matrices

    ERIC Educational Resources Information Center

    Adachi, Kohei

    2009-01-01

    In component analysis solutions, post-multiplying a component score matrix by a nonsingular matrix can be compensated by applying its inverse to the corresponding loading matrix. To eliminate this indeterminacy on nonsingular transformation, we propose Joint Procrustes Analysis (JPA) in which component score and loading matrices are simultaneously…

  10. The Effects of Load Carriage and Muscle Fatigue on Lower-Extremity Joint Mechanics

    ERIC Educational Resources Information Center

    Wang, He; Frame, Jeff; Ozimek, Elicia; Leib, Daniel; Dugan, Eric L.

    2013-01-01

    Military personnel are commonly afflicted by lower-extremity overuse injuries. Load carriage and muscular fatigue are major stressors during military basic training. Purpose: To examine effects of load carriage and muscular fatigue on lower-extremity joint mechanics during walking. Method: Eighteen men performed the following tasks: unloaded…

  11. Loading Analysis of Composite Wind Turbine Blade for Fatigue Life Prediction of Adhesively Bonded Root Joint

    NASA Astrophysics Data System (ADS)

    Salimi-Majd, Davood; Azimzadeh, Vahid; Mohammadi, Bijan

    2015-06-01

    Nowadays wind energy is widely used as a non-polluting cost-effective renewable energy resource. During the lifetime of a composite wind turbine which is about 20 years, the rotor blades are subjected to different cyclic loads such as aerodynamics, centrifugal and gravitational forces. These loading conditions, cause to fatigue failure of the blade at the adhesively bonded root joint, where the highest bending moments will occur and consequently, is the most critical zone of the blade. So it is important to estimate the fatigue life of the root joint. The cohesive zone model is one of the best methods for prediction of initiation and propagation of debonding at the root joint. The advantage of this method is the possibility of modeling the debonding without any requirement to the remeshing. However in order to use this approach, it is necessary to analyze the cyclic loading condition at the root joint. For this purpose after implementing a cohesive interface element in the Ansys finite element software, one blade of a horizontal axis wind turbine with 46 m rotor diameter was modelled in full scale. Then after applying loads on the blade under different condition of the blade in a full rotation, the critical condition of the blade is obtained based on the delamination index and also the load ratio on the root joint in fatigue cycles is calculated. These data are the inputs for fatigue damage growth analysis of the root joint by using CZM approach that will be investigated in future work.

  12. A novel wearable measurement system for ambulatory assessment of joint loading in the occupational setting.

    PubMed

    Faber, Gert; Chang, Chien-Chi; Kingma, Idsart; Dennerlein, Jack T

    2012-01-01

    It is know that biomechanical overexposure of the joints is an important cause of occupational injuries. This paper presents a novel wearable measurement system for automated assessment of joint loading in the occupational setting. The wearable measurement system consists of a full body inertial sensor motion capture system which can be worn under the clothes and shoes instrumented with 3D force sensors (ForceShoes). Promising results have been found for the performance of the inertial sensor system and the ForceShoe, separately. Validation experiments are in preparation in which the performance of the combined measurements system will be tested in the laboratory by comparing the assessed joint loading to the joint loading assessed by a conventional state-of-the-art lab-based method. PMID:22317604

  13. Role of the Acetabular Labrum in Load Support Across the Hip Joint

    PubMed Central

    Henak, Corinne R.; Ellis, Benjamin J.; Harris, Michael D.; Anderson, Andrew E.; Peters, Christopher L.; Weiss, Jeffrey A.

    2011-01-01

    The relatively high incidence of labral tears among patients presenting with hip pain suggests that the acetabular labrum is often subjected to injurious loading in vivo. However, it is unclear whether the labrum participates in load transfer across the joint during activities of daily living. This study examined the role of the acetabular labrum in load transfer for hips with normal acetabular geometry and acetabular dysplasia using subject-specific finite element analysis. Models were generated from volumetric CT data and analyzed with and without the labrum during activities of daily living. The labrum in the dysplastic model supported 4-11% of the total load transferred across the joint, while the labrum in the normal model supported only 1-2% of the total load. Despite the increased load transferred to the acetabular cartilage in simulations without the labrum, there were minimal differences in cartilage contact stresses. This was because the load supported by the cartilage correlated to the cartilage contact area. A higher percentage of load was transferred to the labrum in the dysplastic model because the femoral head achieved equilibrium near the lateral edge of the acetabulum. The results of this study suggest that the labrum plays a larger role in load transfer and joint stability in hips with acetabular dysplasia than in hips with normal acetabular geometry. PMID:21757198

  14. Knee Joint Loads and Surrounding Muscle Forces during Stair Ascent in Patients with Total Knee Replacement

    PubMed Central

    Rasnick, Robert; Standifird, Tyler; Reinbolt, Jeffrey A.; Cates, Harold E.

    2016-01-01

    Total knee replacement (TKR) is commonly used to correct end-stage knee osteoarthritis. Unfortunately, difficulty with stair climbing often persists and prolongs the challenges of TKR patents. Complete understanding of loading at the knee is of great interest in order to aid patient populations, implant manufacturers, rehabilitation, and future healthcare research. Musculoskeletal modeling and simulation approximates joint loading and corresponding muscle forces during a movement. The purpose of this study was to determine if knee joint loadings following TKR are recovered to the level of healthy individuals, and determine the differences in muscle forces causing those loadings. Data from five healthy and five TKR patients were selected for musculoskeletal simulation. Variables of interest included knee joint reaction forces (JRF) and the corresponding muscle forces. A paired samples t-test was used to detect differences between groups for each variable of interest (p<0.05). No differences were observed for peak joint compressive forces between groups. Some muscle force compensatory strategies appear to be present in both the loading and push-off phases. Evidence from knee extension moment and muscle forces during the loading response phase indicates the presence of deficits in TKR in quadriceps muscle force production during stair ascent. This result combined with greater flexor muscle forces resulted in similar compressive JRF during loading response between groups. PMID:27258086

  15. Knee Joint Loads and Surrounding Muscle Forces during Stair Ascent in Patients with Total Knee Replacement.

    PubMed

    Rasnick, Robert; Standifird, Tyler; Reinbolt, Jeffrey A; Cates, Harold E; Zhang, Songning

    2016-01-01

    Total knee replacement (TKR) is commonly used to correct end-stage knee osteoarthritis. Unfortunately, difficulty with stair climbing often persists and prolongs the challenges of TKR patents. Complete understanding of loading at the knee is of great interest in order to aid patient populations, implant manufacturers, rehabilitation, and future healthcare research. Musculoskeletal modeling and simulation approximates joint loading and corresponding muscle forces during a movement. The purpose of this study was to determine if knee joint loadings following TKR are recovered to the level of healthy individuals, and determine the differences in muscle forces causing those loadings. Data from five healthy and five TKR patients were selected for musculoskeletal simulation. Variables of interest included knee joint reaction forces (JRF) and the corresponding muscle forces. A paired samples t-test was used to detect differences between groups for each variable of interest (p<0.05). No differences were observed for peak joint compressive forces between groups. Some muscle force compensatory strategies appear to be present in both the loading and push-off phases. Evidence from knee extension moment and muscle forces during the loading response phase indicates the presence of deficits in TKR in quadriceps muscle force production during stair ascent. This result combined with greater flexor muscle forces resulted in similar compressive JRF during loading response between groups. PMID:27258086

  16. Inter-joint coupling strategy during adaptation to novel viscous loads in human arm movement.

    PubMed

    Debicki, D B; Gribble, P L

    2004-08-01

    When arm movements are perturbed by a load, how does the nervous system adjust control signals to reduce error? While it has been shown that the nervous system is capable of compensating for the effects of limb dynamics and external forces, the strategies used to adapt to novel loads are not well understood. We used a robotic exoskeleton [kinesiological instrument for normal and altered reaching movements (KINARM)] to apply novel loads to the arm during single-joint elbow flexions in the horizontal plane (shoulder rotation was allowed). Loads varied in magnitude with the instantaneous velocity of elbow flexion, and were applied to the shoulder in experiment 1 (interaction loads) and the elbow in experiment 2 (direct loads). Initial exposure to both interaction and direct loads resulted in perturbations at both joints, even though the load was applied to only a single joint. Subjects tended to correct for the kinematics of the elbow joint while perturbations at the shoulder persisted. Electromyograms (EMGs) and computed muscle torque showed that subjects modified muscle activity at the elbow to reduce elbow positional deviations. Shoulder muscle activity was also modified; however, these changes were always in the same direction as those at the elbow. Current models of motor control based on inverse-dynamics calculations and force-control, as well as models based on positional control, predict an uncoupling of shoulder and elbow muscle torques for adaptation to these loads. In contrast, subjects in this study adopted a simple strategy of modulating the natural coupling that exists between elbow and shoulder muscle torque during single-joint elbow movements. PMID:15056688

  17. Stress analysis method for clearance-fit joints with bearing-bypass loads

    NASA Technical Reports Server (NTRS)

    Naik, R. A.; Crews, J. H., Jr.

    1989-01-01

    Within a multi-fastener joint, fastener holes may be subjected to the combined effects of bearing loads and loads that bypass the hole to be reacted elsewhere in the joint. The analysis of a joint subjected to search combined bearing and bypass loads is complicated by the usual clearance between the hole and the fastener. A simple analysis method for such clearance-fit joints subjected to bearing-bypass loading has been developed in the present study. It uses an inverse formulation with a linear elastic finite-element analysis. Conditions along the bolt-hole contact arc are specified by displacement constraint equations. The present method is simple to apply and can be implemented with most general purpose finite-element programs since it does not use complicated iterative-incremental procedures. The method was used to study the effects of bearing-bypass loading on bolt-hole contact angles and local stresses. In this study, a rigid, frictionless bolt was used with a plate having the properties of a quasi-isotropic graphite/epoxy laminate. Results showed that the contact angle as well as the peak stresses around the hole and their locations were strongly influenced by the ratio of bearing and bypass loads. For single contact, tension and compression bearing-bypass loading had opposite effects on the contact angle. For some compressive bearing-bypass loads, the hole tended to close on the fastener leading to dual contact. It was shown that dual contact reduces the stress concentration at the fastener and would, therefore, increase joint strength in compression. The results illustrate the general importance of accounting for bolt-hole clearance and contact to accurately compute local bolt-hole stresses for combined bearings and bypass loading.

  18. Effects of changing speed on knee and ankle joint load during walking and running.

    PubMed

    de David, Ana Cristina; Carpes, Felipe Pivetta; Stefanyshyn, Darren

    2015-01-01

    Joint moments can be used as an indicator of joint loading and have potential application for sports performance and injury prevention. The effects of changing walking and running speeds on joint moments for the different planes of motion still are debatable. Here, we compared knee and ankle moments during walking and running at different speeds. Data were collected from 11 recreational male runners to determine knee and ankle joint moments during different conditions. Conditions include walking at a comfortable speed (self-selected pacing), fast walking (fastest speed possible), slow running (speed corresponding to 30% slower than running) and running (at 4 m · s(-1) ± 10%). A different joint moment pattern was observed between walking and running. We observed a general increase in joint load for sagittal and frontal planes as speed increased, while the effects of speed were not clear in the transverse plane moments. Although differences tend to be more pronounced when gait changed from walking to running, the peak moments, in general, increased when speed increased from comfortable walking to fast walking and from slow running to running mainly in the sagittal and frontal planes. Knee flexion moment was higher in walking than in running due to larger knee extension. Results suggest caution when recommending walking over running in an attempt to reduce knee joint loading. The different effects of speed increments during walking and running should be considered with regard to the prevention of injuries and for rehabilitation purposes. PMID:25105739

  19. Thrombospondin-4 and excitatory synaptogenesis promote spinal sensitization after painful mechanical joint injury.

    PubMed

    Crosby, Nathan D; Zaucke, Frank; Kras, Jeffrey V; Dong, Ling; Luo, Z David; Winkelstein, Beth A

    2015-02-01

    Facet joint injury induces persistent pain that may be maintained by structural plasticity in the spinal cord. Astrocyte-derived thrombospondins, especially thrombospondin-4 (TSP4), have been implicated in synaptogenesis and spinal sensitization in neuropathic pain, but the TSP4 response and its relationship to synaptic changes in the spinal cord have not been investigated for painful joint injury. This study investigates the role of TSP4 in the development and maintenance of persistent pain following injurious facet joint distraction in rats and tests the hypothesis that excitatory synaptogenesis contributes to such pain. Painful facet joint loading induces dorsal horn excitatory synaptogenesis along with decreased TSP4 in the DRG and increased astrocytic release of TSP4 in the spinal cord, all of which parallel the time course of sustained tactile allodynia. Blocking injury-induced spinal TSP4 expression with antisense oligonucleotides or reducing TSP4 activity at its neuronal receptor in the spinal cord with gabapentin treatment both attenuate the allodynia and dorsal horn synaptogenesis that develop after painful facet joint loading. Increased spinal TSP4 also facilitates the development of allodynia and spinal hyperexcitability, even after non-painful physiological loading of the facet joint. These results suggest that spinal TSP4 plays an important role in the development and maintenance of persistent joint-mediated pain by inducing excitatory synaptogenesis and facilitating the transduction of mechanical loading of the facet joint that leads to spinal hyperexcitability. PMID:25483397

  20. Lower extremity joint loading during level walking with Masai barefoot technology shoes in overweight males.

    PubMed

    Buchecker, M; Wagner, H; Pfusterschmied, J; Stöggl, T L; Müller, E

    2012-06-01

    The purpose of this study was to evaluate the effects of Masai barefoot technology (MBT) shoes on lower extremity joint loading in overweight males during level walking. Therefore, lower extremity kinematics, kinetics, and muscle electromyographic signals of the vastus lateralis (VL), biceps femoris (BF), and gastrocnemius medialis (GM) were recorded in 10 overweight males at a self-chosen walking speed with MBT shoes and conventional shoes. Selected peak joint moments, maximal joint force loading rates, mean muscle intensities, and co-activation indices of the VL/BF, as well as of the VL/GM were analyzed and compared for the two shoe conditions using paired Student's t-tests (α=0.05). Results showed that walking with MBT shoes reduced first peak knee adduction moments in overweight subjects. During midstance and terminal stance, increases in VL/GM co-activation, accompanied by increases in VL and GM (only terminal stance) intensities were found for the MBT situation. Kinetic variables analyzed to assess ankle and hip joint loading did not exhibit any statistical differences. These results suggest that using MBT shoes diminishes medial compartment loads at the knee without overloading hip or ankle joints in overweight males. However, the additional muscle loading should not be overlooked, and warrants further investigation. PMID:20807383

  1. Analysis of the Constraint Joint Loading in the Thumb During Pipetting

    PubMed Central

    Sinsel, Erik W.; Zhao, Kristin D.; An, Kai-Nan; Buczek, Frank L.

    2015-01-01

    Dynamic loading on articular joints is essential for the evaluation of the risk of the articulation degeneration associated with occupational activities. In the current study, we analyzed the dynamic constraint loading for the thumb during pipetting. The constraint loading is considered as the loading that has to be carried by the connective tissues of the joints (i.e., the cartilage layer and the ligaments) to maintain the kinematic constraints of the system. The joint loadings are solved using a classic free-body approach, using the external loading and muscle forces, which were obtained in an inverse dynamic approach combined with an optimization procedure in anybody. The constraint forces in the thumb joint obtained in the current study are compared with those obtained in the pinch and grasp tests in a previous study (Cooney and Chao, 1977, “Biomechanical Analysis of Static Forces in the Thumb During Hand Function,” J. Bone Joint Surg. Am., 59(1), pp. 27–36). The maximal compression force during pipetting is approximately 83% and 60% greater than those obtained in the tip pinch and key pinch, respectively, while substantially smaller than that obtained during grasping. The maximal lateral shear force is approximately six times, 32 times, and 90% greater than those obtained in the tip pinch, key pinch, and grasp, respectively. The maximal dorsal shear force during pipetting is approximately 3.2 and 1.4 times greater than those obtained in the tip pinch and key pinch, respectively, while substantially smaller than that obtained during grasping. Our analysis indicated that the thumb joints are subjected to repetitive, intensive loading during pipetting, compared to other daily activities. PMID:25839321

  2. Optical examination of load transfer in riveted lap joints using portable holographic interferometry

    NASA Astrophysics Data System (ADS)

    Shankar, Krishnakumar; Baird, John P.; Clark, Robert K.; Williamson, Hugh M.

    1997-03-01

    In mechanically fastened single lap joints, such as those employed on aircraft fuselage skin splices, there are two distinct mechanisms of load transfer. At low values of load the transfer occurs primarily through friction between the component sheets while at higher loads the load is transferred by friction as well as through bearing at the fasteners. The load level at which the bearing mode of load transfer comes into action significantly affects the fatigue life of the joint, since the fasteners are stressed only at loads above this threshold load value. The portable holographic interferometry testing system (PHITS) is a robust, portable and sensitive non-destructive inspection system which produces contours of relative out of plane displacement by the method of superposition. PHITS is applied here to monitor the load transfer mechanism and identify the threshold at which the bearing mode comes into effect. In the friction mode there is no relative displacement between the fasteners and the skin panels. In the bearing mode the fasteners are loaded, causing a distinct tipping of the rivets, which is readily observable in the fringe pattern of deflection contours recorded by the holographic system.

  3. Daptomycin-loaded polymethylmethacrylate bone cement for joint arthroplasty surgery.

    PubMed

    Hsu, Yuan-Ming; Liao, Chun-Hsing; Wei, Yu-Hong; Fang, Hsu-Wei; Hou, Hsiang-Huan; Chen, Chia-Chun; Chang, Chih-Hung

    2014-06-01

    Antibiotic-loaded acrylic bone cement has been frequently used as an infection prophylaxis or antibiotic-loaded spacer in infected arthroplasty. In addition, daptomycin has been used recently against broad spectrum Gram-positive organisms. The goal of this in vitro study is to investigate the bacteriacidal and mechanical properties of daptomycin-incorporated polymethylmethacrylate (PMMA) bone cement and evaluate its feasibility for clinical use. Daptomycin (0.5, 1, or 2 g) was premixed with 40 g of PMMA bone cement powder before curing. The mechanical properties of the daptomycin-loaded acrylic bone cement (DLABC) were estimated following standard guidance, and the release profile and kinetics of daptomycin from PMMA were analyzed. The antimicrobial efficacy of DLABC was determined with a zone of inhibition (ZOI) assay against Staphylococcus aureus, Staphylococcus epidermis, Enterococcus faecalis, and Enterococcus faecium, respectively. The results showed that the compressive strength, of PMMA bone cement, which was higher than 100 MPa in all groups, was sufficient according to ISO 5833 after incorporation of daptomycin. The encapsulated daptomycin was released for 2 weeks with a 9.59 ± 0.85%, 15.25 ± 0.69%, and 20.64 ± 20.33% released percentage on the first day in the low, mid, and high groups, respectively. According to the calculated release kinetics, incorporated daptomycin should be 3.3 times the original dose to double its release. Although all recipes of DLABC had a microbial inhibitory effect, the effect with a higher encapsulated amount of daptomycin was more significant. Therefore, we believe that daptomycin can be locally delivered from PMMA bone cement at the surgical site as a prophylactic or treatment for osteomyelitis against Gram-positive organisms with intact cement function. PMID:24571555

  4. Facets: Ersatz, Resource and Tag

    ERIC Educational Resources Information Center

    Frické, Martin H.

    2013-01-01

    Introduction: Faceted classification appears to be of utmost importance. Ersatz facets, resource faceting and tag faceting: The distinctions are drawn between facets and ersatz facets, and between faceted resources and faceted tags. Single tag resource faceting and multiple tag information object faceting: The basic features are explored of single…

  5. The exoskeletal structure and tensile loading behavior of an ant neck joint.

    PubMed

    Nguyen, Vienny; Lilly, Blaine; Castro, Carlos

    2014-01-22

    Insects have evolved mechanical form and function over millions of years. Ants, in particular, can lift and carry heavy loads relative to their body mass. Loads are lifted with the mouthparts, transferred through the neck joint to the thorax, and distributed over six legs and tarsi (feet) that anchor to the supporting surface. While previous research has explored attachment mechanisms of the tarsi, little is known about the relation between the mechanical function and the structural design and material properties of the ant. This study focuses on the neck--the single joint that withstands the full load capacity. We combine mechanical testing, computed tomography (CT), scanning electron microscopy (SEM), and computational modeling to better understand the mechanical structure-function relation of the neck joint of the ant species Formica exsectoides (Allegheny mound ant). Our mechanical testing results show that the soft tissue forming the neck joint of F. exsectoides exhibits an elastic modulus of 230±140 MPa and can withstand ~5000 times the ant's weight. We developed a 3-dimensional (3D) model of the structural components of the neck joint for simulation of mechanical behavior. Finite element (FE) simulations reveal the neck-to-head transition where the soft membrane material meets the hard exoskeleton as the critical point for failure of the neck joint, which is consistent with our experiments. Our results further indicate that the neck joint structure exhibits anisotropic mechanical behavior with the highest stiffness occurring when the load path is aligned with the axis of the neck. PMID:24287400

  6. In Situ Deformation of Cartilage in Cyclically Loaded Tibiofemoral Joints by Displacement-Encoded MRI

    PubMed Central

    Chan, D.D.; Neu, C.P.; Hull, M.L.

    2009-01-01

    Objectives Cartilage displacement and strain patterns were documented noninvasively in intact tibiofemoral joints in situ by magnetic resonance imaging (MRI). This study determined the number of compressive loading cycles required to precondition intact joints prior to imaging, the spatial distribution of displacements and strains in cartilage using displacement-encoded MRI, and the depth-dependency of these measures across specimens. Design Juvenile porcine tibiofemoral joints were cyclically compressed at one and two times body weight at 0.1 Hz to achieve quasi-steady state load-displacement response. A 7T MRI scanner was used for displacement-encoded stimulated echoes with a fast spin echo acquisition (DENSE-FSE) in eight intact joints. Two-dimensional displacements and strains were determined throughout the thickness of the tibial and femoral cartilage and then normalized over the tissue thickness. Results Two-dimensional displacements and strains were heterogeneous through the depth of femoral and tibial cartilage under cyclic compression. Strains in the loading direction were compressive and were maximal in the middle zone of femoral and tibial cartilage, and tensile strains were observed in the direction transverse to loading. Conclusions This study determined the depth-dependent displacements and strains in intact juvenile porcine tibiofemoral joints using displacement-encoded imaging. Displacement and strain distributions reflect the heterogeneous biochemistry of cartilage and the biomechanical response of the tissue to compression in the loading environment of an intact joint. This unique information about the biomechanics of cartilage has potential for comparisons of healthy and degenerated tissue and in the design of engineered replacement tissues. PMID:19447213

  7. Hip and knee joint loading during vertical jumping and push jerking

    PubMed Central

    Cleather, Daniel J; Goodwin, Jon E; Bull, Anthony MJ

    2014-01-01

    Background The internal joint contact forces experienced at the lower limb have been frequently studied in activities of daily living and rehabilitation activities. In contrast, the forces experienced during more dynamic activities are not well understood, and those studies that do exist suggest very high degrees of joint loading. Methods In this study a biomechanical model of the right lower limb was used to calculate the internal joint forces experienced by the lower limb during vertical jumping, landing and push jerking (an explosive exercise derived from the sport of Olympic weightlifting), with a particular emphasis on the forces experienced by the knee. Findings The knee experienced mean peak loadings of 2.4-4.6 × body weight at the patellofemoral joint, 6.9-9.0 × body weight at the tibiofemoral joint, 0.3-1.4 × body weight anterior tibial shear and 1.0-3.1 × body weight posterior tibial shear. The hip experienced a mean peak loading of 5.5-8.4 × body weight and the ankle 8.9-10.0 × body weight. Interpretation The magnitudes of the total (resultant) joint contact forces at the patellofemoral joint, tibiofemoral joint and hip are greater than those reported in activities of daily living and less dynamic rehabilitation exercises. The information in this study is of importance for medical professionals, coaches and biomedical researchers in improving the understanding of acute and chronic injuries, understanding the performance of prosthetic implants and materials, evaluating the appropriateness of jumping and weightlifting for patient populations and informing the training programmes of healthy populations. PMID:23146164

  8. Load Variation Influences on Joint Work During Squat Exercise in Reduced Gravity

    NASA Technical Reports Server (NTRS)

    DeWitt, John K.; Fincke, Renita S.; Logan, Rachel L.; Guilliams, Mark E.; Ploutz-Snyder, Lori L.

    2011-01-01

    Resistance exercises that load the axial skeleton, such as the parallel squat, are incorporated as a critical component of a space exercise program designed to maximize the stimuli for bone remodeling and muscle loading. Astronauts on the International Space Station perform regular resistance exercise using the Advanced Resistive Exercise Device (ARED). Squat exercises on Earth entail moving a portion of the body weight plus the added bar load, whereas in microgravity the body weight is 0, so all load must be applied via the bar. Crewmembers exercising in microgravity currently add approx.70% of their body weight to the bar load as compensation for the absence of the body weight. This level of body weight replacement (BWR) was determined by crewmember feedback and personal experience without any quantitative data. The purpose of this evaluation was to utilize computational simulation to determine the appropriate level of BWR in microgravity necessary to replicate lower extremity joint work during squat exercise in normal gravity based on joint work. We hypothesized that joint work would be positively related to BWR load.

  9. Interfacial stress in a carbon-to-metal bond joint under thermal shock loading

    SciTech Connect

    You, J.H.

    1998-02-01

    The duplex bond joint consisting of a metallic substrate armored with carbon-base materials is a promising candidate configuration for application to high heat flux operations. When a bond joint is subjected to thermal loadings, significant thermal stresses may develop due to mismatch of the thermal expansion coefficients. Stress intensification occurs near the free surface edge of the interface, sometimes showing singularity. The singular stress fields are critical for understanding the loading nature of the bond interface in a joint system. In this paper, thermal stresses in the bond interface of a carbon-to-molybdenum joint element were investigated. A high heat flux (HHF) pulse was assumed as the reference load history to simulate the thermal shock condition. The thermomechanical behavior was described quantitatively in terms of the stress intensity factor. The stress solutions of the singular field computed by the theoretical approach showed a good agreement with the numerical results of the finite element analysis. The stress intensity factor of the singular stress fields near the free surface edge of the interface showed a time variation similar to that of the bulk stress. The temperature gradient induced by the transient HHF load affected the overall interfacial stress only slightly.

  10. Failure Predictions of Out-of-Autoclave Sandwich Joints with Delaminations Under Flexure Loads

    NASA Technical Reports Server (NTRS)

    Nordendale, Nikolas; Goyal, Vinay; Lundgren, Eric; Patel, Dhruv; Farrokh, Babak; Jones, Justin; Fischetti, Grace; Segal, Kenneth

    2015-01-01

    An analysis and a test program was conducted to investigate the damage tolerance of composite sandwich joints. The joints contained a single circular delamination between the face-sheet and the doubler. The coupons were fabricated through out-of-autoclave (OOA) processes, a technology NASA is investigating for joining large composite sections. The four-point bend flexure test was used to induce compression loading into the side of the joint where the delamination was placed. The compression side was chosen since it tends to be one of the most critical loads in launch vehicles. Autoclave cure was used to manufacture the composite sandwich sections, while the doubler was co-bonded onto the sandwich face-sheet using an OOA process after sandwich panels were cured. A building block approach was adopted to characterize the mechanical properties of the joint material, including the fracture toughness between the doubler and face-sheet. Twelve four-point-bend samples were tested, six in the sandwich core ribbon orientation and six in sandwich core cross-ribbon direction. Analysis predicted failure initiation and propagation at the pre-delaminated location, consistent with experimental observations. Fracture analyses methods predicted failure loads in close agreement with tests. This investigation demonstrated a strength reduction of 10 percent due to a flaw of significant size compared to the width of the sample. Therefore, concerns of bonding an OOA material to an in-autoclave material was mitigated for the geometries, materials, and load configurations considered.

  11. Failure Predictions of Out-of-Autoclave Sandwich Joints with Delaminations under Flexure Loads

    NASA Technical Reports Server (NTRS)

    Nordendale, Nikolas; Goyal, Vinay; Lundgren, Eric; Patel, Dhruv; Farrokh, Babak; Jones, Justin; Fischetti, Grace; Segal, Kenneth

    2015-01-01

    An analysis and a test program was conducted to investigate the damage tolerance of composite sandwich joints. The joints contained a single circular delamination between the face-sheet and the doubler. The coupons were fabricated through out-of-autoclave (OOA) processes, a technology NASA is investigating for joining large composite sections. The four-point bend flexure test was used to induce compression loading into the side of the joint where the delamination was placed. The compression side was chosen since it tends to be one of the most critical loads in launch vehicles. Autoclave cure was used to manufacture the composite sandwich sections, while the doubler was co-bonded onto the sandwich face-sheet using an OOA process after sandwich panels were cured. A building block approach was adopted to characterize the mechanical properties of the joint material, including the fracture toughness between the doubler and facesheet. Twelve four-point-bend samples were tested, six in the sandwich core ribbon orientation and six in sandwich core cross-ribbon direction. Analysis predicted failure initiation and propagation at the pre-delaminated location, consistent with experimental observations. A building block approach using fracture analyses methods predicted failure loads in close agreement with tests. This investigation demonstrated a small strength reduction due to a flaw of significant size compared to the width of the sample. Therefore, concerns of bonding an OOA material to an in-autoclave material was mitigated for the geometries, materials, and load configurations considered.

  12. Failure Predictions of Out-of-Autoclave Sandwich Joints with Delaminations Under Flexure Loads

    NASA Technical Reports Server (NTRS)

    Nordendale, Nikolas A.; Goyal, Vinay K.; Lundgren, Eric C.; Patel, Dhruv N.; Farrokh, Babak; Jones, Justin; Fischetti, Grace; Segal, Kenneth N.

    2015-01-01

    An analysis and a test program was conducted to investigate the damage tolerance of composite sandwich joints. The joints contained a single circular delamination between the face-sheet and the doubler. The coupons were fabricated through out-of-autoclave (OOA) processes, a technology NASA is investigating for joining large composite sections. The four-point bend flexure test was used to induce compression loading into the side of the joint where the delamination was placed. The compression side was chosen since it tends to be one of the most critical loads in launch vehicles. Autoclave cure was used to manufacture the composite sandwich sections, while the doubler was co-bonded onto the sandwich face-sheet using an OOA process after sandwich panels were cured. A building block approach was adopted to characterize the mechanical properties of the joint material, including the fracture toughness between the doubler and face-sheet. Twelve four-point-bend samples were tested, six in the sandwich core ribbon orientation and six in sandwich core cross-ribbon direction. Analysis predicted failure initiation and propagation at the pre-delaminated location, consistent with experimental observations. A building block approach using fracture analyses methods predicted failure loads in close agreement with tests. This investigation demonstrated a small strength reduction due to a flaw of significant size compared to the width of the sample. Therefore, concerns of bonding an OOA material to an in-autoclave material was mitigated for the geometries, materials, and load configurations considered.

  13. Bolted Double-Lap Composite Joints Under Mechanical and Thermal Loading

    NASA Technical Reports Server (NTRS)

    Kradinov, V.; Barut, A.; Madenci, E.; Walker, Sandra P. (Technical Monitor)

    2000-01-01

    This study concerns the determination of the contact stresses and contact region around bolt holes and the bolt load distribution in single- and double-lap joints of composite laminates with arbitrarily located bolts under general mechanical loading conditions and uniform temperature change. The unknown contact stress distribution and contact region between the bolt and laminates and the interaction among the bolts require the bolt load distribution, as well as the contact stresses, to be as part of the solution. The present method is based on the complex potential theory and the variational formulation in order to account for bolt stiffness, bolt-hole clearance, and finite geometry of the composite laminates.

  14. Abnormal loading of the major joints in knee osteoarthritis and the response to knee replacement.

    PubMed

    Metcalfe, Andrew; Stewart, Caroline; Postans, Neil; Barlow, David; Dodds, Alexander; Holt, Cathy; Whatling, Gemma; Roberts, Andrew

    2013-01-01

    Knee osteoarthritis is common and patients frequently complain that they are 'overloading' the joints of the opposite leg when they walk. However, it is unknown whether moments or co-contractions are abnormal in the unaffected joints of patients with single joint knee osteoarthritis, or how they change following treatment of the affected knee. Twenty patients with single joint medial compartment knee osteoarthritis were compared to 20 asymptomatic control subjects. Gait analysis was performed for normal level gait and surface EMG recordings of the medial and lateral quadriceps and hamstrings were used to investigate co-contraction. Patients were followed up 12 months post-operatively and the analysis was repeated. Results are presented for the first 14 patients who have attended follow-up. Pre-operatively, adduction moment impulses were elevated at both knees and the contra-lateral hip compared to controls. Co-contraction of hamstrings and quadriceps was elevated bilaterally. Post-operatively, moment waveforms returned to near-normal levels at the affected knee and co-contraction fell in the majority of patients. However, abnormalities persisted in the contra-lateral limb with partial or no recovery of both moment waveforms and co-contraction in the majority. Patients with knee osteoarthritis do experience abnormal loads of their major weight bearing joints bilaterally, and abnormalities persist despite treatment of the affected limb. Further treatment may be required if we are to protect the other major joints following joint arthroplasty. PMID:22841587

  15. The Effect of Foot Structure on 1st Metatarsophalangeal Joint Flexibility and Hallucal Loading

    PubMed Central

    Rao, Smita; Song, Jinsup; Kraszewski, Andrew; Backus, Sherry; Ellis, Scott J.; Deland, Jonathan T.; Hillstrom, Howard J.

    2011-01-01

    The purpose of our study was to examine 1st metatarsophalangeal (MTP) joint motion and flexibility and plantar loads in individuals with high, normal and low arch foot structure. Asymptomatic individuals (n=61), with high, normal and low arches participated in this study. Foot structure was quantified using malleolar valgus index (MVI) and arch height index (AHI). First MTP joint flexibility was measured using a specially constructed jig. Peak pressure under the hallux, 1st and 2nd metatarsals during walking was assessed using a pedobarograph. A one-way ANOVA with Bonferroni-adjusted post-hoc comparisons was used to assess between-group differences in MVI, AHI, Early and Late 1st MTP joint flexibility in sitting and standing, peak dorsiflexion (DF), and peak pressure under the hallux, 1st and 2nd metatarsals. Stepwise linear regression was used to identify predictors of hallucal loading. Significant between-group differences were found in MVI (F2,56=15.4, p<0.01), 1st MTP late flexibility in sitting (F2,57=3.7, p=0.03), and standing (F2,57=3.7, p=0.03). Post-hoc comparisons demonstrated that 1st MTP late flexibility in sitting was significantly higher in individuals with low arch compared to high arch structure, and that 1st MTP late flexibility in standing was significantly higher in individuals with low arch compared to normal arch structure. Stepwise regression analysis indicated that MVI and 1st MTP joint early flexibility in sitting explain about 20% of the variance in hallucal peak pressure. Our results provide objective evidence indicating that individuals with low arches show increased 1st MTP joint late flexibility compared to individuals with normal arch structure, and that hindfoot alignment and 1st MTP joint flexibility affect hallucal loading. PMID:21536440

  16. Does surgical approach or prosthesis type affect hip joint loading one year after surgery?

    PubMed

    Wesseling, Mariska; Meyer, Christophe; Corten, Kristoff; Simon, Jean-Pierre; Desloovere, Kaat; Jonkers, Ilse

    2016-02-01

    Several approaches may be used for hip replacement surgery either in combination with conventional total hip arthroplasty (THA) or resurfacing hip arthroplasty (RHA). This study investigates the differences in hip loading during gait one year or more after surgery in three cohorts presenting different surgical procedures, more specific RHA placed using the direct lateral (RHA-DLA, n=8) and posterolateral (RHA-PLA, n=14) approach as well as THA placed using the direct anterior (THA-DAA, n=12) approach. For the DAA and control subjects, hip loading was also evaluated during stair ascent and descent to evaluate whether these motions can better discriminate between patients and controls compared to gait. Musculoskeletal modelling in OpenSim was used to calculate in vivo joint loading. Results showed that for all operated patients, regardless the surgical procedure, hip loading was decreased compared to control subjects, while no differences were found between patient groups. This indicates that THA via DAA results in similar hip loading as a RHA via DLA or PLA. Stair climbing did not result in more distinct differences in hip contact force magnitude between patients and controls, although differences in orientation were more distinct. However, patients after hip surgery did adjust their motion pattern to decrease the magnitude of loading on the hip joint compared to control subjects. PMID:27004636

  17. Experimental investigation of T-tubular joint subjected to complex loading conditions

    NASA Astrophysics Data System (ADS)

    Lie, S. T.; Chiew, S. P.; Sun, S.

    2001-06-01

    This paper describes the results of a large-scale experimental test on T-tubular welded joint subjected under combined loading conditions. A special purpose rig is constructed for conducting the static and dynamic test of different tubular welded joints in the laboratory. The static test results are reported herein. Both the Strain gauge specimen testing which includes the basic brace axial, in-plane-bending, out-of-plane-bending and combined loadings cases, and also the finite element analyses had been carried out. The result obtained by the finite element analyses proved the accuracy and reliability of the numerical modeling. The study shows that the peak hot spot locations on the T-tubular joint subjected to combine loading shift from those of the basic load case. Generally, the peak hot spot stresses obtained by superposition are higher than that by direct analysis except for the areas that are near to the peak hot spot stresses location. The hot spot locations are important to decide on the placement of probes used in the fatigue test using the Alternating Current Potential Drop technique.

  18. The friction coefficient of shoulder joints remains remarkably low over 24 h of loading.

    PubMed

    Jones, Brian K; Durney, Krista M; Hung, Clark T; Ateshian, Gerard A

    2015-11-01

    The frictional response of whole human joints over durations spanning activities of daily living has not been reported previously. This study measured the friction of human glenohumeral joints during 24 h of reciprocal loading in a pendulum testing device, at moderate (0.2 mm/s, 4320 cycles) and low (0.02 mm/s, 432 cycles) sliding speeds, under a 200 N load. The effect of joint congruence was also investigated by testing human humeral heads against significantly larger mature bovine glenoids. Eight human joints and six bovine joints were tested in four combinations: human joints tested at moderate (hHCMS, n=6) and low speed (hHCLS, n=3), human humeral heads tested against bovine glenoids at moderate speed (LCMS, n=3), and bovine joints tested at moderate speed (bHCMS, n=3). In the first half hour the mean±standard deviation of the friction coefficient was hHCMS: 0.0016±0.0011, hHCLS: 0.0012±0.0002, LCMS: 0.0008±0.0002 and bHCMS: 0.0024±0.0008; in the last four hours it was hHCMS: 0.0057±0.0025, hHCLS: 0.0047±0.0017, LCMS: 0.0012±0.0003 and bHCMS: 0.0056±0.0016. The initial value was lower than the final value (p<0.0001). The value in LCMS was significantly lower than in hHCMS and bHCMS (p<0.01). No visual damage was observed in any of the specimens. These are the first results to demonstrate that the friction coefficient of natural human shoulders remains remarkably low (averaging as little as 0.0015 and no greater than 0.006) for up to 24 h of continuous loading. The sustained low friction coefficients observed in incongruent joints (~0.001) likely represent rolling rather than sliding friction. PMID:26472306

  19. Drill string splined resilient tubular telescopic joint for balanced load drilling of deep holes

    SciTech Connect

    Garrett, W.R.

    1981-08-04

    A drill string splined resilient tubular telescopic joint for balanced load deep well drilling comprises a double acting damper having a very low spring rate upon both extension and contraction from the zero deflection condition. Preferably the spring means itself is a double acting compression spring means wherein the same spring means is compressed whether the joint is extended or contracted. The damper has a like low spring rate over a considerable range of deflection, both upon extension and contraction of the joint, but a gradually then rapidly increased spring rate upon approaching the travel limits in each direction. Stacks of spring rings are employed for the spring means, the rings being either shaped elastomer-metal sandwiches or, preferably, roller belleville springs. The spline and spring means are disposed in an annular chamber formed by mandrel and barrel members constituting the telescopic joint. The spring rings make only such line contact with one of the telescoping members as is required for guidance therefrom, and no contact with the other member. The chamber containing the spring means, and also containing the spline means, is filled with lubricant, the chamber being sealed with a pressure seal at its lower end and an inverted floating seal at its upper end. Magnetic and electrical means are provided to check for the presence and condition of the lubricant. To increase load capacity the spring means is made of a number of components acting in parallel.

  20. In Vivo Dynamic Deformation of Articular Cartilage in Intact Joints Loaded by Controlled Muscular Contractions.

    PubMed

    Abusara, Ziad; Von Kossel, Markus; Herzog, Walter

    2016-01-01

    When synovial joints are loaded, the articular cartilage and the cells residing in it deform. Cartilage deformation has been related to structural tissue damage, and cell deformation has been associated with cell signalling and corresponding anabolic and catabolic responses. Despite the acknowledged importance of cartilage and cell deformation, there are no dynamic data on these measures from joints of live animals using muscular load application. Research in this area has typically been done using confined and unconfined loading configurations and indentation testing. These loading conditions can be well controlled and allow for accurate measurements of cartilage and cell deformations, but they have little to do with the contact mechanics occurring in a joint where non-congruent cartilage surfaces with different material and functional properties are pressed against each other by muscular forces. The aim of this study was to measure in vivo, real time articular cartilage deformations for precisely controlled static and dynamic muscular loading conditions in the knees of mice. Fifty and 80% of the maximal knee extensor muscular force (equivalent to approximately 0.4N and 0.6N) produced average peak articular cartilage strains of 10.5±1.0% and 18.3±1.3% (Mean ± SD), respectively, during 8s contractions. A sequence of 15 repeat, isometric muscular contractions (0.5s on, 3.5s off) of 50% and 80% of maximal muscular force produced cartilage strains of 3.0±1.1% and 9.6±1.5% (Mean ± SD) on the femoral condyles of the mouse knee. Cartilage thickness recovery following mechanical compression was highly viscoelastic and took almost 50s following force removal in the static tests. PMID:26807930

  1. In Vivo Dynamic Deformation of Articular Cartilage in Intact Joints Loaded by Controlled Muscular Contractions

    PubMed Central

    Abusara, Ziad; Von Kossel, Markus; Herzog, Walter

    2016-01-01

    When synovial joints are loaded, the articular cartilage and the cells residing in it deform. Cartilage deformation has been related to structural tissue damage, and cell deformation has been associated with cell signalling and corresponding anabolic and catabolic responses. Despite the acknowledged importance of cartilage and cell deformation, there are no dynamic data on these measures from joints of live animals using muscular load application. Research in this area has typically been done using confined and unconfined loading configurations and indentation testing. These loading conditions can be well controlled and allow for accurate measurements of cartilage and cell deformations, but they have little to do with the contact mechanics occurring in a joint where non-congruent cartilage surfaces with different material and functional properties are pressed against each other by muscular forces. The aim of this study was to measure in vivo, real time articular cartilage deformations for precisely controlled static and dynamic muscular loading conditions in the knees of mice. Fifty and 80% of the maximal knee extensor muscular force (equivalent to approximately 0.4N and 0.6N) produced average peak articular cartilage strains of 10.5±1.0% and 18.3±1.3% (Mean ± SD), respectively, during 8s contractions. A sequence of 15 repeat, isometric muscular contractions (0.5s on, 3.5s off) of 50% and 80% of maximal muscular force produced cartilage strains of 3.0±1.1% and 9.6±1.5% (Mean ± SD) on the femoral condyles of the mouse knee. Cartilage thickness recovery following mechanical compression was highly viscoelastic and took almost 50s following force removal in the static tests. PMID:26807930

  2. Influences of Alignment and Obesity on Knee Joint Loading in Osteoarthritic Gait

    PubMed Central

    Messier, Stephen P.; Pater, Mackenzie; Beavers, Daniel P.; Legault, Claudine; Loeser, Richard F.; Hunter, David J.; DeVita, Paul

    2014-01-01

    Objective To determine the influences of frontal plane knee alignment and obesity on knee joint loads in older, overweight and obese adults with knee osteoarthritis. Methods Cross-sectional investigation of alignment and obesity on knee joint loads using community dwelling older adults (age ≥ 55 yrs.; 27 kg·m−2 ≥ BMI ≤ 41 kg·m−2; 69% female) with radiographic knee osteoarthritis that were a subset of participants (157 out of 454) enrolled in the Intensive Diet and Exercise for Arthritis (IDEA) clinical trial. Results A higher BMI was associated with greater (p = 0.0006) peak knee compressive forces [overweight, 2411 N (2182, 2639), class 1 obesity, 2772 N (2602, 2943), class 2+ obesity, 2993 N (2796, 3190)] and greater (p = 0.004) shear forces [overweight, 369 N (322, 415), class 1 obesity, 418 N (384, 453), class 2+ obesity, 472 N (432, 513)], independent of alignment, and varus alignment was associated (p < 0.0001) with greater peak external knee adduction moments, independent of BMI [valgus, 18.7 Nm (15.1, 22.4), neutral, 27.7 Nm (24.0, 31.4), varus, 37.0 Nm (34.4, 39.7)]. Conclusion BMI and alignment were associated with different joint loading measures; alignment was more closely associated with the asymmetry or imbalance of loads across the medial and lateral knee compartments as reflected by the frontal plane external adduction moment, while BMI was associated with the magnitude of total tibio-femoral force. These data may be useful in selecting treatment options for knee osteoarthritis patients (e.g., diet to reduce compressive loads or bracing to change alignment). PMID:24857973

  3. Loads in the hip joint during physically demanding occupational tasks: A motion analysis study.

    PubMed

    Varady, Patrick Aljoscha; Glitsch, Ulrich; Augat, Peter

    2015-09-18

    Epidemiologic studies of osteoarthritis of the hip indicate a possible connection between work related activities and the pathogenesis of the disease. This study investigated the hip joint contact forces for physically demanding occupational tasks (lifting, carrying, transferring of a weight (mass: 25 kg, 40 kg and 50 kg); stair climbing without and with additional load of 25 kg; ladder climbing) and compared these with everyday activities (level gait, sitting down and getting up). The hip joint contact force was calculated with the human multibody simulation software AnyBody employing motion capture and ground reaction force measurements by force plates and an instrumented staircase and ladder. Although the results for 11 male test subjects showed individual variations, a general trend could be observed in regards of force curves' characteristics and maxima. The largest joint contact forces calculated were (637 ± 148)%-body weight for horizontal transfer of a 50 kg weight. For several of the occupational activities the computed hip joint contact forces were significantly larger compared to the investigated examples of activities of daily living. This study provides original data of simulated hip joint contact forces for physically demanding activities. PMID:26187677

  4. Shoulder joint loading in the high performance flat and kick tennis serves

    PubMed Central

    Reid, Machar; Elliott, Bruce; Alderson, Jacque

    2007-01-01

    Objective To quantify and compare the full body kinematics and shoulder joint kinetics during the high‐performance tennis flat (FS) and kick serves (KS). Methods A 12‐camera 250 Hz, Vicon motion analysis system recorded the three‐dimensional FS and KS of 12 high‐performance male players. A total of 22 paired Student's t tests, with an accompanying partial Bonferroni correction (p<0.01), determined statistically significant differences between the variables of interest in both serves. Results Higher peak horizontal, vertical and absolute racquet velocities were developed during the FS, while higher lateral velocities characterised the KS. Similar shoulder joint kinematics and kinetics punctuated both serves, but with some variation in trunk and lower limb mechanics. Conclusions Similar shoulder joint kinetics assisted the development of varying three‐dimensional racquet velocities in the FS and KS. The comparable shoulder joint loading conditions point to the repetitive, long‐term performance of either serve as relevant in shoulder joint injury pathologies. PMID:17513331

  5. The Load Distribution in Bolted or Riveted Joints in Light-Alloy Structures

    NASA Technical Reports Server (NTRS)

    Vogt, F.

    1947-01-01

    This report contains a theoretical discussion of the load distribution in bolted or riveted joints in light-alloy structures which is applicable not only for loads below the limit of proportionality but also for loads above this limit. The theory is developed for double and single shear joints. The methods given are illustrated by numerical examples and the values assumed for the bolt (or rivet) stiffnesses are based partly on theory and partly on known experimental values. It is shown that the load distribution does not vary greatly with the bolt (or rivet) stiffnesses and that for design purposes it is usually sufficient to know their order of magnitude. The theory may also be directly used for spot-welded structures and, with small modifications, for seam-welded structures, The computational work involved in the methods described is simple and may be completed in a reasonable time for most practical problems. A summary of earlier theoretical and experimental investigations on the subject is included in the report.

  6. Joint Seasonal ARMA Approach for Modeling of Load Forecast Errors in Planning Studies

    SciTech Connect

    Hafen, Ryan P.; Samaan, Nader A.; Makarov, Yuri V.; Diao, Ruisheng; Lu, Ning

    2014-04-14

    To make informed and robust decisions in the probabilistic power system operation and planning process, it is critical to conduct multiple simulations of the generated combinations of wind and load parameters and their forecast errors to handle the variability and uncertainty of these time series. In order for the simulation results to be trustworthy, the simulated series must preserve the salient statistical characteristics of the real series. In this paper, we analyze day-ahead load forecast error data from multiple balancing authority locations and characterize statistical properties such as mean, standard deviation, autocorrelation, correlation between series, time-of-day bias, and time-of-day autocorrelation. We then construct and validate a seasonal autoregressive moving average (ARMA) model to model these characteristics, and use the model to jointly simulate day-ahead load forecast error series for all BAs.

  7. Determination of three-dimensional joint loading within the lower extremities in snowboarding.

    PubMed

    Krüger, Andreas; McAlpine, Paul; Borrani, Fabio; Edelmann-Nusser, Jürgen

    2012-02-01

    In the biomechanical literature only a few studies are available focusing on the determination of joint loading within the lower extremities in snowboarding. These studies are limited to analysis in a restricted capture volume due to the use of optical video-based systems. To overcome this restriction the aim of the present study was to develop a method to determine net joint moments within the lower extremities in snowboarding for complete measurement runs. An experienced snowboarder performed several runs equipped with two custom-made force plates as well as a full-body inertial measurement system. A rigid, multi-segment model was developed to describe the motion and loads within the lower extremities. This model is based on an existing lower-body model and designed to be run by the OpenSim software package. Measured kinetic and kinematic data were imported into the OpenSim program and inverse dynamic calculations were performed. The results illustrate the potential of the developed method for the determination of joint loadings within the lower extremities for complete measurement runs in a real snowboarding environment. The calculated net joint moments of force are reasonable in comparison to the data presented in the literature. A good reliability of the method seems to be indicated by the low data variation between different turns. Due to the unknown accuracy of this method the application for inter-individual studies as well as studies of injury mechanisms may be limited. For intra-individual studies comparing different snowboarding techniques as well as different snowboard equipment the method seems to be beneficial. The validity of the method needs to be studied further. PMID:22468468

  8. The Effects of Common Footwear on Joint Loading in Osteoarthritis of the Knee

    PubMed Central

    Shakoor, Najia; Sengupta, Mondira; Foucher, Kharma C.; Wimmer, Markus A.; Fogg, Louis F.; Block, Joel A.

    2010-01-01

    Objective Elevated joint loads during walking have been associated with the severity and progression of osteoarthritis (OA) of the knee. Footwear may have the potential to alter these loads. This study compared the effects of several common shoe types on knee loading in subjects with OA of the knee. Methods 31 subjects (10 men, 21 women) with radiographic and symptomatic knee OA underwent gait analyses using an optoelectronic camera system and multi-component force plate. In each case, gait was evaluated barefoot and while wearing 4 different shoes: 1) clogs (Dansko®), 2) stability shoes (Brooks Addiction®), 3) flat walking shoes (Puma H Street®), and 4) flip-flops. Peak knee loads were compared between the different footwear conditions. Results Overall, the clogs and stability shoes, resulted in a significantly higher peak knee adduction moment (3.1±0.7 and 3.0±0.7 %BW*ht, respectively, ~15% higher, p<0.05)) compared with that of flat walking shoes (2.8±0.7%BW*ht), flip-flops (2.7±0.8%BW*ht) and barefoot walking (2.7±0.7%BW*ht). There were no statistically significant differences in knee loads with the flat walking shoes and flip-flops compared to barefoot walking. Conclusions These data confirm that footwear may have significant effects on knee loads during walking in subjects with OA of the knee. Flexibility and heel height may be important differentiating characteristics of shoes which affect knee loads. In light of the strong relationship between knee loading and OA, the design and biomechanical effects of modern footwear should be more closely evaluated in terms of their effects on the disease. PMID:20191571

  9. Mechanical Properties of Lead-Free Solder Joints Under High-Speed Shear Impact Loading

    NASA Astrophysics Data System (ADS)

    Nguyen, Van Luong; Kim, Ho-Kyung

    2014-09-01

    In this study we expanded on recently reported research by using a modified miniature Charpy impact-testing system to investigate the shear deformation behavior of Sn-3.0Ag-0.5Cu lead-free solder joints at high strain rates ranging from 1.1 × 103 s-1 to 5.5 × 103 s-1. The experimental results revealed that the maximum shear strength of the solder joint decreased with increasing load speed in the ranges tested in this study. For solder joints tested at a shear speed exceeding 1 m/s, corresponding to an approximate strain rate that exceeds 1950 s-1, the brittle fracture mode is the main failure mode, whereas lower strain rates result in a ductile-to-brittle transition in the fracture surfaces of solder joints. In addition, the mode II stress intensity factor (K II) used to evaluate the fracture toughness (K C) of an interfacial intermetallic compound layer between Sn-3.0Ag-0.5Cu solder and the toughness of copper substrate was found to decrease from 1.63 MPa m0.5 to 0.97 MPa m0.5 in the speed range tested here.

  10. Mechanical Properties of Lead-Free Solder Joints Under High-Speed Shear Impact Loading

    NASA Astrophysics Data System (ADS)

    Nguyen, Van Luong; Kim, Ho-Kyung

    2014-11-01

    In this study we expanded on recently reported research by using a modified miniature Charpy impact-testing system to investigate the shear deformation behavior of Sn-3.0Ag-0.5Cu lead-free solder joints at high strain rates ranging from 1.1 × 103 s-1 to 5.5 × 103 s-1. The experimental results revealed that the maximum shear strength of the solder joint decreased with increasing load speed in the ranges tested in this study. For solder joints tested at a shear speed exceeding 1 m/s, corresponding to an approximate strain rate that exceeds 1950 s-1, the brittle fracture mode is the main failure mode, whereas lower strain rates result in a ductile-to-brittle transition in the fracture surfaces of solder joints. In addition, the mode II stress intensity factor ( K II) used to evaluate the fracture toughness ( K C) of an interfacial intermetallic compound layer between Sn-3.0Ag-0.5Cu solder and the toughness of copper substrate was found to decrease from 1.63 MPa m0.5 to 0.97 MPa m0.5 in the speed range tested here.

  11. Optimum design of bolted composite lap joints under mechanical and thermal loading

    NASA Astrophysics Data System (ADS)

    Kradinov, Vladimir Yurievich

    A new approach is developed for the analysis and design of mechanically fastened composite lap joints under mechanical and thermal loading. Based on the combined complex potential and variational formulation, the solution method satisfies the equilibrium equations exactly while the boundary conditions are satisfied by minimizing the total potential. This approach is capable of modeling finite laminate planform dimensions, uniform and variable laminate thickness, laminate lay-up, interaction among bolts, bolt torque, bolt flexibility, bolt size, bolt-hole clearance and interference, insert dimensions and insert material properties. Comparing to the finite element analysis, the robustness of the method does not decrease when modeling the interaction of many bolts; also, the method is more suitable for parametric study and design optimization. The Genetic Algorithm (GA), a powerful optimization technique for multiple extrema functions in multiple dimensions search spaces, is applied in conjunction with the complex potential and variational formulation to achieve optimum designs of bolted composite lap joints. The objective of the optimization is to acquire such a design that ensures the highest strength of the joint. The fitness function for the GA optimization is based on the average stress failure criterion predicting net-section, shear-out, and bearing failure modes in bolted lap joints. The criterion accounts for the stress distribution in the thickness direction at the bolt location by applying an approach utilizing a beam on an elastic foundation formulation.

  12. Adhesive-bonded double-lap joints. [analytical solutions for static load carrying capacity

    NASA Technical Reports Server (NTRS)

    Hart-Smith, L. J.

    1973-01-01

    Explicit analytical solutions are derived for the static load carrying capacity of double-lap adhesive-bonded joints. The analyses extend the elastic solution Volkersen and cover adhesive plasticity, adherend stiffness imbalance and thermal mismatch between the adherends. Both elastic-plastic and bi-elastic adhesive representations lead to the explicit result that the influence of the adhesive on the maximum potential bond strength is defined uniquely by the strain energy in shear per unit area of bond. Failures induced by peel stresses at the ends of the joint are examined. This failure mode is particularly important for composite adherends. The explicit solutions are sufficiently simple to be used for design purposes

  13. Effects of Specialized Footwear on Joint Loads in Osteoarthritis of the Knee

    PubMed Central

    Shakoor, Najia; Lidtke, Roy H.; Sengupta, Mondira; Fogg, Louis F.; Block, Joel A.

    2013-01-01

    Objective Elevated dynamic joint loads have been associated with the severity and progression of osteoarthritis (OA) of the knee. This study compared the effects of a specialized shoe (the mobility shoe) designed to lower dynamic loads at the knee with self-chosen conventional walking shoes and with a commercially available walking shoe as a control. Methods Subjects with knee OA were evaluated in 2 groups. Group A (n = 28) underwent gait analyses with both their self-chosen walking shoes and the mobility shoes. Group B (n = 20) underwent gait analyses with a control shoe and the mobility shoe. Frontal plane knee loads were compared between the different footwear conditions. Results Group A demonstrated an 8% reduction in the peak external knee adduction moment with the mobility shoe compared with self-chosen walking shoes (mean ± SD 49 ± 0.80 versus 2.71 ± 0.84 %BW × H; P < 0.05). Group B demonstrated a 12% reduction in the peak external knee adduction moment with the mobility shoe compared with the control shoe (mean ± SD 2.66 ± 0.69 versus 3.07 ± 0.75 %BW × H; P < 0.05). Conclusion Specialized footwear can effectively reduce joint loads in subjects with knee OA, compared with self-chosen shoes and control walking shoes. Footwear may represent a therapeutic target for the treatment of knee OA. The types of shoes worn by subjects with knee OA should be evaluated more closely in terms of their effects on the disease. PMID:18759313

  14. Mode 1 delamination growth in adhesively bonded joints under static and fatigue loads

    NASA Technical Reports Server (NTRS)

    Biswas, S. C.; Jeelani, S.

    1986-01-01

    The objective of this investigation was to characterize the pure mode 1 delamination growth in metal to metal adhesively bonded joints under static and fatigue loading conditions, using FM 73 adhesive. Double cantilever beam specimens (DCB) were used for pure mode 1 tests. Aluminum 2024-T3 adherends were bonded with FM 73 adhesive. Delamination was introduced during fabrication by inserting a Teflon film between the two adherends. The mode 1 strain energy release rate G sub I sub c was obtained directly from static DCB tests conducted in accordance with the ASTM designation D1876-12. Constant amplitude fatigue tests on DCB specimens were conducted to determine the relationship between delamination growth rate da/dN and strain energy release rate G sub I sub c for a pure mode 1 delamination growth. It is found that the debond propagation rate in adhesive joints using FM 73 is more sensitive to errors in design load than is typical crack growth rate in metallic structures.

  15. Gaze-induced joint attention persists under high perceptual load and does not depend on awareness.

    PubMed

    Xu, Shan; Zhang, Shen; Geng, Haiyan

    2011-09-15

    The automaticity of gaze-induced joint attention is well known in relatively easy cognitive tasks; but its role in harder tasks had never been examined. This encouraged us to study automaticity in hard tasks, tasks presenting the subjects with high perceptual loads. The Rapid Serial Visual Presentation (RSVP) paradigm was used to present participants with two streams of bilaterally displayed digit-flows while they fixated at the center of a synthetic representation of a human face. The face was presented both above (Experiments 1 and 2) and below (Experiment 3) the face's visual threshold (henceforth called "supraliminal" and "subliminal", respectively). Interocular suppression was used to make the face stimulus invisible (subliminal). In the critical trials of all three experiments, the gaze direction shown on the face was randomly diverted to either the left or to the right. This directed the participant's gaze either towards or away from the location of a target in the RSVP. The perceptual load was always relatively high. It was either set (Experiments 1 and 3) or manipulated (Experiment 2) during the experiment. In all three experiments, an appreciably higher and significant level of target detection was found when an uninformative gaze-cue was congruent with the location of the target. This result, which had only been reported with relatively easy tasks previously, is called the "gaze-cueing effect". Our novel findings include showing that: (i) the attentional effect of gaze persists under high perceptual loads, and (ii) awareness of the gaze stimuli is not required to obtain the gaze-cueing effect. They also serve to validate prior support for an important role of automaticity in gaze-induced joint attention. PMID:21840332

  16. Dynamic compressive response of the human pelvis axial loading of the sacroiliac joint.

    PubMed

    Kemper, Andrew R; McNally, Craig; Duma, Stefan M

    2008-01-01

    The purpose of this study was to quantify the biomechanical response of the intact human pelvis subjected to dynamic axial compressive loading. Axial compression tests were performed on a total of six fresh frozen human cadaver pelves, five male and one female. The intact pelves were fixed to a load cell with a custom aluminum pot placed around the sacrum. Special care was taken when potting the pelves in order to ensure that the orientation of the pelves was representative of that seen in normal upright seating. The pelves were then subjected to dynamic compressive loading at a rate of approximately 2 m/s using a servo-hydraulic Material Testing System (MTS). The average peak force, moment, and displacement at the point of failure were 5,896 +/- 1455 N, 33.4 +/- 28.6 N-m, and 6.4 +/- 0.7 mm, respectively. The failure of the all pelvis specimens corresponded to a bilateral dislocation of the sacroiliac joint. As a general trend, strain gage data showed that the right and left superior ramus were placed in tension and the right and left ischium were placed in compression. The peak strain values ranged from 746 mstr to 5717 mstr in tension and from -356 mstr to -2677 mstr in compression. The current study will help future researchers reduce the number of incidences and severity of pelvic fractures that can result from falls from heights, ejection seat loading, or motor vehicle crash environments by providing valuable test data that quantifies biomechanical response of the human pelvis in vertical loading. PMID:19141911

  17. On the biomechanics of cycling. A study of joint and muscle load during exercise on the bicycle ergometer.

    PubMed

    Ericson, M

    1986-01-01

    The aim of the study was to quantify the load induced in the lower limb joints and muscles during exercise on a bicycle ergometer and to study how these loads changed with adjustments of the bicycle ergometer or cycling technique. The forces, load moments and muscular power output acting on and about the hip, knee and ankle joints during cycling were determined using cine-film, pedal force measurements and biomechanical calculations based upon static and dynamic mechanics. The muscular activity of eleven lower limb muscles was recorded and quantified using EMG. The load moments acting about the bilateral hip, knee and ankle joint axes were found to be generally lower than those induced during normal level walking. The varus and valgus load moments acting about the antero-posterior knee joint axis were approximately the same as those induced during walking. The tibio-femoral compressive joint force and the anteriorly directed tibio-femoral shear force mainly stressing the anterior cruciate ligament were low. The talocrural joint compressive force and achilles tendon tensile force were low compared to those in level walking. The magnitude of lower limb muscular activity during cycling approximated that obtained during walking, with three major exceptions. M. vastus medialis et lateralis were more activated during cycling than during walking, and tibialis anterior was less activated. The hip extensor muscles produced 27%, hip flexors 4%, knee extensors 39%, knee flexors 10% and ankle plantar flexors 20% of the total positive mechanical work. Of the four parameters studied (workload, pedalling rate, saddle height, pedal foot position) workload was the most important adjustment factor for change of joint load and muscular activity. An increased pedalling rate increased the muscular activity in most of the muscles investigated, generally without changing the joint load. Increased saddle height decreased the maximum flexing knee load moment, but did not significantly

  18. Evaluation of a subject-specific finite-element model of the equine metacarpophalangeal joint under physiological load.

    PubMed

    Harrison, Simon M; Whitton, R Chris; Kawcak, Chris E; Stover, Susan M; Pandy, Marcus G

    2014-01-01

    The equine metacarpophalangeal (MCP) joint is frequently injured, especially by racehorses in training. Most injuries result from repetitive loading of the subchondral bone and articular cartilage rather than from acute events. The likelihood of injury is multi-factorial but the magnitude of mechanical loading and the number of loading cycles are believed to play an important role. Therefore, an important step in understanding injury is to determine the distribution of load across the articular surface during normal locomotion. A subject-specific finite-element model of the MCP joint was developed (including deformable cartilage, elastic ligaments, muscle forces and rigid representations of bone), evaluated against measurements obtained from cadaver experiments, and then loaded using data from gait experiments. The sensitivity of the model to force inputs, cartilage stiffness, and cartilage geometry was studied. The FE model predicted MCP joint torque and sesamoid bone flexion angles within 5% of experimental measurements. Muscle-tendon forces, joint loads and cartilage stresses all increased as locomotion speed increased from walking to trotting and finally cantering. Perturbations to muscle-tendon forces resulted in small changes in articular cartilage stresses, whereas variations in joint torque, cartilage geometry and stiffness produced much larger effects. Non-subject-specific cartilage geometry changed the magnitude and distribution of pressure and the von Mises stress markedly. The mean and peak cartilage stresses generally increased with an increase in cartilage stiffness. Areas of peak stress correlated qualitatively with sites of common injury, suggesting that further modelling work may elucidate the types of loading that precede joint injury and may assist in the development of techniques for injury mitigation. PMID:24210848

  19. A Fatigue Life Prediction Model of Welded Joints under Combined Cyclic Loading

    NASA Astrophysics Data System (ADS)

    Goes, Keurrie C.; Camarao, Arnaldo F.; Pereira, Marcos Venicius S.; Ferreira Batalha, Gilmar

    2011-01-01

    A practical and robust methodology is developed to evaluate the fatigue life in seam welded joints when subjected to combined cyclic loading. The fatigue analysis was conducted in virtual environment. The FE stress results from each loading were imported to fatigue code FE-Fatigue and combined to perform the fatigue life prediction using the S x N (stress x life) method. The measurement or modelling of the residual stresses resulting from the welded process is not part of this work. However, the thermal and metallurgical effects, such as distortions and residual stresses, were considered indirectly through fatigue curves corrections in the samples investigated. A tube-plate specimen was submitted to combined cyclic loading (bending and torsion) with constant amplitude. The virtual durability analysis result was calibrated based on these laboratory tests and design codes such as BS7608 and Eurocode 3. The feasibility and application of the proposed numerical-experimental methodology and contributions for the technical development are discussed. Major challenges associated with this modelling and improvement proposals are finally presented.

  20. The effect of medial meniscectomy and coronal plane angulation on in vitro load transmission in the canine stifle joint.

    PubMed

    Newman, A P; Anderson, D R; Daniels, A U; Jee, K W

    1989-01-01

    The purpose of this study was to determine the in vitro load transmission characteristics of the canine stifle joint, paying particular attention to the positioning effect of the meniscus in the coronal plane. The intact joint was first loaded, and then tested under two different loading conditions after a complete medial meniscectomy. The first set of test conditions attempted to simulate those used by previous investigators, by ignoring the spacer effect of the meniscus and not repositioning the joint after its removal. The second set of tests was carried out after the joint was repositioned in the coronal plane to allow initial contact to occur in both tibiofemoral compartments. It is presumed that this occurs subsequent to a meniscectomy in vivo, following the application of any weight-bearing load. As with previous investigators, it was found that after meniscectomy the joints produced slightly larger displacements and lower stiffnesses than when intact (no significant differences from intact). However, repositioning the meniscectomized joint produced markedly smaller displacements (35-49%, p less than 0.01) and greater stiffnesses (47-123%, p less than 0.05) over the range of forces analyzed, compared with the intact joint. The ratio of dissipated to input energy was 42% for the intact joint, and rose following meniscectomy to 54% (p less than 0.05) with repositioning and 55% (p less than 0.05) without repositioning. Measured contact area decreased by 17% (p less than 0.05) following meniscectomy alone, and by 12% (p less than 0.05) following meniscectomy with repositioning. Since repositioning of the joint subsequent to meniscectomy (accounting for the loss of the meniscal spacer) resulted in an increase in structural stiffness, it was concluded that the medial meniscus decreases the structural stiffness of the intact stifle joint. In addition, the meniscus has a role in elastic energy storage and increasing contact area. This study is intended to serve as a

  1. Relationship between foot function and medial knee joint loading in people with medial compartment knee osteoarthritis

    PubMed Central

    2013-01-01

    Background Dynamic joint loading, particularly the external knee adduction moment (KAM), is an important surrogate measure for the medio-lateral distribution of force across the knee joint in people with knee osteoarthritis (OA). Foot motion may alter the load on the medial tibiofemoral joint and hence affect the KAM. Therefore, this study aimed to investigate the relationship between tibia, rearfoot and forefoot motion in the frontal and transverse planes and the KAM in people with medial compartment knee OA. Method Motion of the knee, tibia, rearfoot and forefoot and knee moments were evaluated in 32 patients with clinically and radiographically-confirmed OA, predominantly in the medial compartment. Pearson’s correlation coefficient was used to investigate the association between peak values of tibia, rearfoot and forefoot motion in the frontal and transverse planes and 1st peak KAM, 2nd peak KAM, and the knee adduction angular impulse (KAAI). Results Lateral tilt of the tibia was significantly associated with increased 1st peak KAM (r = 0.60, p < 0.001), 2nd peak KAM (r = 0.67, p = 0.001) and KAAI (r = 0.82, p = 0.001). Increased peak rearfoot eversion was significantly correlated with decreased 2nd peak KAM (r = 0.59, p < 0.001) and KAAI (r = 0.50, p = 0.004). Decreased rearfoot internal rotation was significantly associated with increased 2nd peak KAM (r = −0.44, p = 0.01) and KAAI (r = −0.38, p = 0.02), while decreased rearfoot internal rotation relative to the tibia was significantly associated with increased 2nd peak KAM (r = 0.43, p = 0.01). Significant negative correlations were found between peak forefoot eversion relative to the rearfoot and 2nd peak KAM (r = −0.53, p = 0.002) and KAAI (r = −0.51, p = 0.003) and between peak forefoot inversion and 2nd peak KAM (r = −0.54, p = 0.001) and KAAI (r = −0.48, p = 0.005). Conclusion Increased rearfoot

  2. Vehicle Routing with Three-dimensional Container Loading Constraints—Comparison of Nested and Joint Algorithms

    NASA Astrophysics Data System (ADS)

    Koloch, Grzegorz; Kaminski, Bogumil

    2010-10-01

    In the paper we examine a modification of the classical Vehicle Routing Problem (VRP) in which shapes of transported cargo are accounted for. This problem, known as a three-dimensional VRP with loading constraints (3D-VRP), is appropriate when transported commodities are not perfectly divisible, but they have fixed and heterogeneous dimensions. In the paper restrictions on allowable cargo positionings are also considered. These restrictions are derived from business practice and they extended the baseline 3D-VRP formulation as considered by Koloch and Kaminski (2010). In particular, we investigate how additional restrictions influence relative performance of two proposed optimization algorithms: the nested and the joint one. Performance of both methods is compared on artificial problems and on a big-scale real life case study.

  3. The mechanical and tribological properties of UHMWPE loaded ALN after mechanical activation for joint replacements.

    PubMed

    Gong, Kemeng; Qu, Shuxin; Liu, Yumei; Wang, Jing; Zhang, Yongchao; Jiang, Chongxi; Shen, Ru

    2016-08-01

    Ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN) has tremendous potential as an orthopeadic biomaterial for joint replacements. However, poor mechanical and tribological properties of UHMWPE-ALN are still obstacle for further application. The purpose of this study was to investigate the effect and mechanism of mechanical activation on mechanical and tribological properties of 1wt% ALN-loaded UHMWPE (UHMWPE-ALN-ma). In this study, tensile test, small punch test and reciprocating sliding wear test were applied to characterize the mechanical and tribological properties of UHMWPE-ALN-ma. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were employed to characterize UHMWPE-ALN-ma. Tensile test and small punch test showed that Young׳s modulus, tensile strength and work-to-failure (WTF) of UHMWPE-ALN-ma increased significantly compared to those of UHMWPE-ALN. The friction coefficients and wear factors of UHMWPE-ALN-ma both decreased significantly compared to those of UHMWPE-ALN. Mechanical activation obviously reduced type 1 (void) and type 2 (the disconnected and dislocated machining marks) fusion defects of UHMWPE-ALN-ma, which were revealed by SEM images of freeze fracture surfaces after etching and lateral surfaces of specimens after extension to fracture, respectively. It was attributed to peeled-off layers and chain scission of molecular chains of UHMWPE particles after mechanical activation, which were revealed by SEM images and FTIR spectra of UHMWPE-ALN-ma and UHMWPE-ALN, respectively. Moreover, EDS spectra revealed the more homogeneous distribution of ALN in UHMWPE-ALN-ma compared to that of UHMWPE-ALN. The present results showed that mechanical activation was a potential strategy to improve mechanical and tribological properties of UHMWPE-ALN-ma as an orthopeadic biomaterial for joint replacements. PMID:27104932

  4. KNEE-JOINT LOADING IN KNEE OSTEOARTHRITIS: INFLUENCE OF ABDOMINAL AND THIGH FAT

    PubMed Central

    Messier, Stephen P.; Beavers, Daniel P.; Loeser, Richard F.; Carr, J. Jeffery; Khajanchi, Shubham; Legault, Claudine; Nicklas, Barbara J.; Hunter, David J.; DeVita, Paul

    2014-01-01

    Purpose Using three separate models that included total body mass, total lean and total fat mass, and abdominal and thigh fat as independent measures, we determined their association with knee-joint loads in older overweight and obese adults with knee osteoarthritis (OA). Methods Fat depots were quantified using computed tomography and total lean and fat mass determined with dual energy x-ray absorptiometry in 176 adults (age = 66.3 yr., BMI = 33.5 kg·m−2) with radiographic knee OA. Knee moments and joint bone-on-bone forces were calculated using gait analysis and musculoskeletal modeling. Results Higher total body mass was significantly associated (p ≤ 0.0001) with greater knee compressive and shear forces, compressive and shear impulses (p < 0.0001), patellofemoral forces (p< 0.006), and knee extensor moments (p = 0.003). Regression analysis with total lean and total fat mass as independent variables revealed significant positive associations of total fat mass with knee compressive (p = 0.0001), shear (p < 0.001), and patellofemoral forces (p = 0.01) and knee extension moment (p = 0.008). Gastrocnemius and quadriceps forces were positively associated with total fat mass. Total lean mass was associated with knee compressive force (p = 0.002). A regression model that included total thigh and total abdominal fat found both were significantly associated with knee compressive and shear forces (p ≤ 0.04). Thigh fat was associated with the knee abduction (p = 0.03) and knee extension moment (p = 0.02). Conclusions Thigh fat, consisting predominately of subcutaneous fat, had similar significant associations with knee joint forces as abdominal fat despite its much smaller volume and could be an important therapeutic target for people with knee OA. PMID:25133996

  5. Three-dimensional knee joint loading in alpine skiing: a comparison between a carved and a skidded turn.

    PubMed

    Klous, Miriam; Müller, Erich; Schwameder, Hermann

    2012-12-01

    Limited data exists on knee biomechanics in alpine ski turns despite the high rate of injuries associated with this maneuver. The purpose of the current study was to compare knee joint loading between a carved and a skidded ski turn and between the inner and outer leg. Kinetic data were collected using Kistler mobile force plates. Kinematic data were collected with five synchronized, panning, tilting, and zooming cameras. Inertial properties of the segments were calculated using an extended version of the Yeadon model. Knee joint forces and moments were calculated using inverse dynamics analysis. The obtained results indicate that knee joint loading in carving is not consistently greater than knee joint loading in skidding. In addition, knee joint loading at the outer leg is not always greater than at the inner leg. Differentiation is required between forces and moments, the direction of the forces and moments, and the phase of the turn that is considered. Even though the authors believe that the analyzed turns are representative, results have to be interpreted with caution due to the small sample size. PMID:22660886

  6. Drill string splined resilient tubular telescopic joint for balanced load drilling of deep holes

    SciTech Connect

    Garrett, W.R.

    1984-03-06

    A drill string splined resilient tubular telescopic joint for balanced load deep well drilling comprises a double acting damper having a very low spring rate upon both extension and contraction from the zero deflection condition. Stacks of spring rings are employed for the spring means, the rings being either shaped elastomer-metal sandwiches or, preferably, roller Belleville springs. The spline and spring means are disposed in an annular chamber formed by mandrel and barrel members constituting the telescopic joint. The chamber containing the spring means, and also containing the spline means, is filled with lubricant, the chamber being sealed with a pressure seal at its lower end and an inverted floating seal at its upper end. A prototype includes of this a bellows seal instead of the floating seal at the upper end of the tool, and a bellows in the side of the lubricant chamber provides volume compensation. A second lubricant chamber is provided below the pressure seal, the lower end of the second chamber being closed by a bellows seal and a further bellows in the side of the second chamber providing volume compensation. Modifications provide hydraulic jars.

  7. Controlled medial branch anesthetic block in the diagnosis of chronic lumbar facet joint pain: the value of a three-month follow-up

    PubMed Central

    da Rocha, Ivan Dias; Cristante, Alexandre Fogaça; Marcon, Raphael Martus; Oliveira, Reginaldo Perilo; Letaif, Olavo Biraghi; de Barros Filho, Tarcisio Eloy Pessoa

    2014-01-01

    OBJECTIVES: To verify the incidence of facetary and low back pain after a controlled medial branch anesthetic block in a three-month follow-up and to verify the correlation between the positive results and the demographic variables. METHODS: Patients with chronic lumbar pain underwent a sham blockade (with a saline injection) and then a controlled medial branch block. Their symptoms were evaluated before and after the sham injection and after the real controlled medial branch block; the symptoms were reevaluated after one day and one week, as well as after one, two and three months using the visual analog scale. We searched for an association between the positive results and the demographic characteristics of the patients. RESULTS: A total of 104 controlled medial branch blocks were performed and 54 patients (52%) demonstrated >50% improvements in pain after the blockade. After three months, lumbar pain returned in only 18 individuals, with visual analogue scale scores >4. Therefore, these patients were diagnosed with chronic facet low back pain. The three-months of follow-up after the controlled medial branch block excluded 36 patients (67%) with false positive results. The results of the controlled medial branch block were not correlated to sex, age, pain duration or work disability but were correlated with patient age (p<0.05). CONCLUSION: Patient diagnosis with a controlled medial branch block proved to be effective but was not associated with any demographic variables. A three-month follow-up is required to avoid a high number of false positives. PMID:25141111

  8. Plasma Wakefield Experiments at FACET

    SciTech Connect

    Hogan, M.J.; England, R.J.; Frederico, J.; Hast, C.; Li, S.Z.; Litos, M.; Walz, D.; An, W.; Clayton, C.E.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.; Tochitsky, S.; Muggli, P.; Pinkerton, S.; Shi, Y.; /Southern California U.

    2011-08-19

    FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration beginning in summer 2011. The nominal FACET parameters are 23GeV, 3nC electron bunches compressed to {approx}20{micro}m long and focused to {approx}10{micro}m wide. The intense fields of the FACET bunches will be used to field ionize neutral lithium or cesium vapor produced in a heat pipe oven. Previous experiments at the SLAC FFTB facility demonstrated 50GeV/m gradients in an 85cm field ionized lithium plasma where the interaction distance was limited by head erosion. Simulations indicate the lower ionization potential of cesium will decrease the rate of head erosion and increase single stage performance. The initial experimental program will compare the performance of lithium and cesium plasma sources with single and double bunches. Later experiments will investigate improved performance with a pre-ionized cesium plasma. The status of the experiments and expected performance are reviewed. The FACET Facility is being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration. The facility will begin commissioning in summer 2011 and conduct an experimental program over the coming five years to study electron and positron beam driven plasma acceleration with strong wake loading in the non-linear regime. The FACET experiments aim to demonstrate high-gradient acceleration of electron and positron beams with high efficiency and negligible emittance growth.

  9. Gender Dimorphic ACL Strain In Response to Combined Dynamic 3D Knee Joint Loading: Implications for ACL Injury Risk

    PubMed Central

    Mizuno, Kiyonori; Andrish, Jack T.; van den Bogert, Antonie J.; McLean, Scott G.

    2009-01-01

    While gender-based differences in knee joint anatomies/laxities are well documented, the potential for them to precipitate gender-dimorphic ACL loading and resultant injury risk has not been considered. To this end, we generated gender-specific models of ACL strain as a function of any six degrees of freedom (6DOF) knee joint load state via a combined cadaveric and analytical approach. Continuously varying joint forces and torques were applied to five male and five female cadaveric specimens and recorded along with synchronous knee flexion and ACL strain data. All data (~10,000 samples) were submitted to specimen-specific regression analyses, affording ACL strain predictions as a function of the combined 6 DOF knee loads. Following individual model verifications, generalized gender-specific models were generated and subjected to 6 DOF external load scenarios consistent with both a clinical examination and a dynamic sports maneuver. The ensuing model-based strain predictions were subsequently examined for gender-based discrepancies. Male and female specimen specific models predicted ACL strain within 0.51% ± 0.10% and 0.52% ± 0.07% of the measured data respectively, and explained more than 75% of the associated variance in each case. Predicted female ACL strains were also significantly larger than respective male values for both of simulated 6 DOF load scenarios. Outcomes suggest that the female ACL will rupture in response to comparatively smaller external load applications. Future work must address the underlying anatomical/laxity contributions to knee joint mechanical and resultant ACL loading, ultimately affording prevention strategies that may cater to individual joint vulnerabilities. PMID:19464897

  10. Decreased Knee Joint Loading Associated With Early Knee Osteoarthritis After Anterior Cruciate Ligament Injury

    PubMed Central

    Wellsandt, Elizabeth; Gardinier, Emily S.; Manal, Kurt; Axe, Michael J.; Buchanan, Thomas S.; Snyder-Mackler, Lynn

    2015-01-01

    Background Anterior cruciate ligament (ACL) injury predisposes individuals to early-onset knee joint osteoarthritis (OA). Abnormal joint loading is apparent after ACL injury and reconstruction. The relationship between altered joint biomechanics and the development of knee OA is unknown. Hypothesis Altered knee joint kinetics and medial compartment contact forces initially after injury and reconstruction are associated with radiographic knee OA 5 years after reconstruction. Study Design Case-control study; Level of evidence, 3. Methods Individuals with acute, unilateral ACL injury completed gait analysis before (baseline) and after (posttraining) preoperative rehabilitation and at 6 months, 1 year, and 2 years after reconstruction. Surface electromyographic and knee biomechanical data served as inputs to an electromyographically driven musculoskeletal model to estimate knee joint contact forces. Patients completed radiographic testing 5 years after reconstruction. Differences in knee joint kinetics and contact forces were compared between patients with and those without radiographic knee OA. Results Patients with OA walked with greater frontal plane interlimb differences than those without OA (nonOA) at baseline (peak knee adduction moment difference: 0.00 ± 0.08 N·m/kg·m [nonOA] vs −0.15 ± 0.09 N·m/kg·m [OA], P = .014; peak knee adduction moment impulse difference: −0.001 ± 0.032 N·m·s/kg·m [nonOA] vs −0.048 ± 0.031 N·m·s/kg·m [OA], P = .042). The involved limb knee adduction moment impulse of the group with osteoarthritis was also lower than that of the group without osteoarthritis at baseline (0.087 ± 0.023 N·m·s/kg·m [nonOA] vs 0.049 ± 0.018 N·m·s/kg·m [OA], P = .023). Significant group differences were absent at posttraining but reemerged 6 months after reconstruction (peak knee adduction moment difference: 0.02 ± 0.04 N·m/kg·m [nonOA] vs −0.06 ± 0.11 N·m/kg·m [OA], P = .043). In addition, the OA group walked with lower peak

  11. Antimicrobial-Loaded Bone Cement Does Not Negatively Influence Sonicate Fluid Culture Positivity for Diagnosis of Prosthetic Joint Infection.

    PubMed

    Park, Kyung-Hwa; Greenwood-Quaintance, Kerryl E; Hanssen, Arlen D; Abdel, Matthew P; Patel, Robin

    2016-06-01

    We compared culture results to investigate the influence of antimicrobial-loaded cement on sonicate fluid culture positivity for the diagnosis of prosthetic joint infection. Fifty-four subjects were assessed. The sensitivities of sonicate fluid culture were 77.8% (14 of 18) in subjects with an antimicrobial-loaded cemented prosthesis and 58.3% (21 of 36) in subjects with an antimicrobial-free prosthesis. PMID:27030490

  12. Seasonal Hydrological Loading in Southern Tibet Detected by Joint Analysis of GPS and GRACE

    PubMed Central

    Zou, Rong; Wang, Qi; Freymueller, Jeffrey T.; Poutanen, Markku; Cao, Xuelian; Zhang, Caihong; Yang, Shaomin; He, Ping

    2015-01-01

    In southern Tibet, ongoing vertical and horizontal motions due to the collision between India and Eurasia are monitored by large numbers of global positioning system (GPS) continuous and campaign sites installed in the past decade. Displacements measured by GPS usually include tectonic deformation as well as non-tectonic, time-dependent signals. To estimate the regional long-term tectonic deformation using GPS more precisely, seasonal elastic deformation signals associated with surface loading must be removed from the observations. In this study, we focus on seasonal variation in vertical and horizontal motions of southern Tibet by performing a joint analysis of GRACE (Gravity Recovery and Climate Experiment) and GPS data, not only using continuous sites but also GPS campaign-mode sites. We found that the GPS-observed and GRACE-modeled seasonal oscillations are in good agreements, and a seasonal displacement model demonstrates that the main reason for seasonal variations in southern Tibet is from the summer monsoon and its precipitation. The biggest loading appears from July to August in the summer season. Vertical deformations observed by GPS and modeled by GRACE are two to three times larger than horizontal oscillations, and the north components demonstrate larger amplitudes than the east components. We corrected the GPS position time series using the GRACE-modeled seasonal variations, which gives significant reductions in the misfit and weighted root-mean-squares (WRMS). Misfit (χ2 divided by degree of freedom) reductions for campaign sites range between 20% and 56% for the vertical component, and are much smaller for the horizontal components. Moreover, time series of continuous GPS (cGPS) sites near the 2015 Nepal earthquakes must be corrected using appropriate models of seasonal loading for analyzing postseismic deformation to avoid biasing estimates of the postseismic relaxation. PMID:26690157

  13. Seasonal Hydrological Loading in Southern Tibet Detected by Joint Analysis of GPS and GRACE.

    PubMed

    Zou, Rong; Wang, Qi; Freymueller, Jeffrey T; Poutanen, Markku; Cao, Xuelian; Zhang, Caihong; Yang, Shaomin; He, Ping

    2015-01-01

    In southern Tibet, ongoing vertical and horizontal motions due to the collision between India and Eurasia are monitored by large numbers of global positioning system (GPS) continuous and campaign sites installed in the past decade. Displacements measured by GPS usually include tectonic deformation as well as non-tectonic, time-dependent signals. To estimate the regional long-term tectonic deformation using GPS more precisely, seasonal elastic deformation signals associated with surface loading must be removed from the observations. In this study, we focus on seasonal variation in vertical and horizontal motions of southern Tibet by performing a joint analysis of GRACE (Gravity Recovery and Climate Experiment) and GPS data, not only using continuous sites but also GPS campaign-mode sites. We found that the GPS-observed and GRACE-modeled seasonal oscillations are in good agreements, and a seasonal displacement model demonstrates that the main reason for seasonal variations in southern Tibet is from the summer monsoon and its precipitation. The biggest loading appears from July to August in the summer season. Vertical deformations observed by GPS and modeled by GRACE are two to three times larger than horizontal oscillations, and the north components demonstrate larger amplitudes than the east components. We corrected the GPS position time series using the GRACE-modeled seasonal variations, which gives significant reductions in the misfit and weighted root-mean-squares (WRMS). Misfit (χ2 divided by degree of freedom) reductions for campaign sites range between 20% and 56% for the vertical component, and are much smaller for the horizontal components. Moreover, time series of continuous GPS (cGPS) sites near the 2015 Nepal earthquakes must be corrected using appropriate models of seasonal loading for analyzing postseismic deformation to avoid biasing estimates of the postseismic relaxation. PMID:26690157

  14. In situ Compressive Loading and Correlative Noninvasive Imaging of the Bone-periodontal Ligament-tooth Fibrous Joint

    PubMed Central

    Jang, Andrew T.; Lin, Jeremy D.; Seo, Youngho; Etchin, Sergey; Merkle, Arno; Fahey, Kevin; Ho, Sunita P.

    2014-01-01

    This study demonstrates a novel biomechanics testing protocol. The advantage of this protocol includes the use of an in situ loading device coupled to a high resolution X-ray microscope, thus enabling visualization of internal structural elements under simulated physiological loads and wet conditions. Experimental specimens will include intact bone-periodontal ligament (PDL)-tooth fibrous joints. Results will illustrate three important features of the protocol as they can be applied to organ level biomechanics: 1) reactionary force vs. displacement: tooth displacement within the alveolar socket and its reactionary response to loading, 2) three-dimensional (3D) spatial configuration and morphometrics: geometric relationship of the tooth with the alveolar socket, and 3) changes in readouts 1 and 2 due to a change in loading axis, i.e. from concentric to eccentric loads. Efficacy of the proposed protocol will be evaluated by coupling mechanical testing readouts to 3D morphometrics and overall biomechanics of the joint. In addition, this technique will emphasize on the need to equilibrate experimental conditions, specifically reactionary loads prior to acquiring tomograms of fibrous joints. It should be noted that the proposed protocol is limited to testing specimens under ex vivo conditions, and that use of contrast agents to visualize soft tissue mechanical response could lead to erroneous conclusions about tissue and organ-level biomechanics. PMID:24638035

  15. Three-Dimensional Lower Extremity Joint Loading in a Carved Ski and Snowboard Turn: A Pilot Study

    PubMed Central

    Müller, Erich

    2014-01-01

    A large number of injuries to the lower extremity occur in skiing and snowboarding. Due to the difficulty of collecting 3D kinematic and kinetic data with high accuracy, a possible relationship between injury statistic and joint loading has not been studied. Therefore, the purpose of the current study was to compare ankle and knee joint loading at the steering leg between carved ski and snowboard turns. Kinetic data were collected using mobile force plates mounted under the toe and heel part of the binding on skies or snowboard (KISTLER). Kinematic data were collected with five synchronized, panning, tilting, and zooming cameras. An extended version of the Yeadon model was applied to calculate inertial properties of the segments. Ankle and knee joint forces and moments were calculated using inverse dynamic analysis. Results showed higher forces along the longitudinal axis in skiing and similar forces for skiing and snowboarding in anterior-posterior and mediolateral direction. Joint moments were consistently greater during a snowboard turn, but more fluctuations were observed in skiing. Hence, when comparing joint loading between carved ski and snowboard turns, one should differentiate between forces and moments, including the direction of forces and moments and the turn phase. PMID:25317202

  16. Three-dimensional lower extremity joint loading in a carved ski and snowboard turn: a pilot study.

    PubMed

    Klous, Miriam; Müller, Erich; Schwameder, Hermann

    2014-01-01

    A large number of injuries to the lower extremity occur in skiing and snowboarding. Due to the difficulty of collecting 3D kinematic and kinetic data with high accuracy, a possible relationship between injury statistic and joint loading has not been studied. Therefore, the purpose of the current study was to compare ankle and knee joint loading at the steering leg between carved ski and snowboard turns. Kinetic data were collected using mobile force plates mounted under the toe and heel part of the binding on skies or snowboard (KISTLER). Kinematic data were collected with five synchronized, panning, tilting, and zooming cameras. An extended version of the Yeadon model was applied to calculate inertial properties of the segments. Ankle and knee joint forces and moments were calculated using inverse dynamic analysis. Results showed higher forces along the longitudinal axis in skiing and similar forces for skiing and snowboarding in anterior-posterior and mediolateral direction. Joint moments were consistently greater during a snowboard turn, but more fluctuations were observed in skiing. Hence, when comparing joint loading between carved ski and snowboard turns, one should differentiate between forces and moments, including the direction of forces and moments and the turn phase. PMID:25317202

  17. Comparison of the efficacy of saline, local anesthetics, and steroids in epidural and facet joint injections for the management of spinal pain: A systematic review of randomized controlled trials

    PubMed Central

    Manchikanti, Laxmaiah; Nampiaparampil, Devi E.; Manchikanti, Kavita N.; Falco, Frank J.E.; Singh, Vijay; Benyamin, Ramsin M.; Kaye, Alan D.; Sehgal, Nalini; Soin, Amol; Simopoulos, Thomas T.; Bakshi, Sanjay; Gharibo, Christopher G.; Gilligan, Christopher J.; Hirsch, Joshua A.

    2015-01-01

    Background: The efficacy of epidural and facet joint injections has been assessed utilizing multiple solutions including saline, local anesthetic, steroids, and others. The responses to these various solutions have been variable and have not been systematically assessed with long-term follow-ups. Methods: Randomized trials utilizing a true active control design were included. The primary outcome measure was pain relief and the secondary outcome measure was functional improvement. The quality of each individual article was assessed by Cochrane review criteria, as well as the criteria developed by the American Society of Interventional Pain Physicians (ASIPP) for assessing interventional techniques. An evidence analysis was conducted based on the qualitative level of evidence (Level I to IV). Results: A total of 31 trials met the inclusion criteria. There was Level I evidence that local anesthetic with steroids was effective in managing chronic spinal pain based on multiple high-quality randomized controlled trials. The evidence also showed that local anesthetic with steroids and local anesthetic alone were equally effective except in disc herniation, where the superiority of local anesthetic with steroids was demonstrated over local anesthetic alone. Conclusion: This systematic review showed equal efficacy for local anesthetic with steroids and local anesthetic alone in multiple spinal conditions except for disc herniation where the superiority of local anesthetic with steroids was seen over local anesthetic alone. PMID:26005584

  18. Is coordination of two-joint leg muscles during load lifting consistent with the strategy of minimum fatigue?

    PubMed

    Prilutsky, B I; Isaka, T; Albrecht, A M; Gregor, R J

    1998-11-01

    The purpose of this study was to examine if strong correlations reported for a back lift task between activity (EMG) of two-joint rectus femoris (RF), hamstrings (HA), and gastrocnemius (GA) and the difference in the joint moments could be predicted by minimizing an objective function of minimum fatigue. Four subjects lifted barbell weights (9 and 18 kg) using a back lift technique at three speeds normal, slow, and fast. Recorded ground reaction forces and coordinates of the leg joints were used to calculate the resultant joint moments. Surface EMG of five muscles crossing the knee joint were also recorded. Forces of nine muscles were calculated using static optimization and a minimum fatigue criterion. Relationships (i) (RF EMG-HA EMG) vs (knee moment hip moment) and (ii) GA EMG vs. (ankle moment knee moment) were closely related (coefficients of determination were typically 0.9 and higher). Qualitatively similar relationships were predicted by minimizing fatigue. Gastrocnemius and hamstrings had the agonistic action at both joints they cross during load lifting, and their activation and predicted forces increased with increasing flexion knee moments and extension ankle and hip moments. The rectus femoris typically had the antagonistic action at the knee and hip, and its activation and predicted force were low. Patterns of predicted muscle forces were qualitatively similar to the corresponding EMG envelopes (except in phases of low joint moments where accuracy of determining joint moments was presumably poor). It was suggested that muscle coordination in load lifting is consistent with the strategy of minimum muscle fatigue. PMID:9880059

  19. NUBEAM Sources in FACETS

    NASA Astrophysics Data System (ADS)

    Pletzer, A.; McCune, D.; Indireshkumar, K.; Morris, A.; Pankin, A.; Cary, J. R.

    2009-05-01

    The SciDAC project for the development of a Framework Application for Core Edge Transport Simulation (FACETS) aims at producing tokamak core-to-wall transport simulations on massively parallel architectures. Here, we report on the progress of integrating the new parallel, PlasmaState based, Monte-Carlo NUBEAM module into the FACETS framework to provide neutral beam and fusion source terms in the plasma core diffusion equations. NUBEAM has recently been improved to facilitate invocation from third party software (e.g. SWIM). This was achieved by consolidating 100s of input variables into separate structures according to machine specificity, shot specificity, or time-slice specificity. Thanks to a combination of auto-generated code and a newly developed methodology for exposing Fortran90 derived types to C, all derived type members of NUBEAM structures have become in-memory accessible to FACETS's C++ infrastructure. NUBEAM, which is the first volumetric-coupling component in FACETS, has been wrapped with methods complying to the FACETS standard interface definition for easy interchangeability of modules at run time. Examples of neutral beam computations instrumented with TAU/Paratools on leadership class machines will be presented, as well as first coupled core-source FACETS simulations.

  20. Numerical Investigation of T-joints with 3D Four Directional Braided Composite Fillers Under Tensile Loading

    NASA Astrophysics Data System (ADS)

    Li, Xiao-kang; Liu, Zhen-guo; Hu, Long; Wang, Yi-bo; Lei, Bing; Huang, Xiang

    2016-08-01

    Numerical studied on T-joints with three-dimensional four directional (3D4D) braided composite fillers was presented in this article. Compared with conventional unidirectional prepreg fillers, the 3D braided composite fillers have excellent ability to prevent crack from penetrating trigone fillers, which constantly occurred in the conventional fillers. Meanwhile, the 3D braided composite fillers had higher fiber volume fraction and eliminated the fiber folding problem in unidirectional prepreg fillers. The braiding technology and mechanical performance of 3D4D braided fillers were studied. The numerical model of carbon fiber T-joints with 3D4D braided composite fillers was built by finite element analysis software. The damage formation, extension and failing process of T-joints with 3D4D braided fillers under tensile load were investigated. Further investigation was extended to the effect of 3D4D braided fillers with different braiding angles on mechanical behavior of the T-joints. The study results revealed that the filling area was the weakest part of the T-joints where the damage first appeared and the crack then rapidly spread to the glue film around the filling area and the interface between over-laminate and soleplate. The 3D4D braided fillers were undamaged and the braiding angle change induced a little effect on the bearing capacity of T-joints.

  1. Determination of hip-joint loading patterns of living and extinct mammals using an inverse Wolff's law approach.

    PubMed

    Christen, Patrik; Ito, Keita; Galis, Frietson; van Rietbergen, Bert

    2015-04-01

    It is well known that bone adapts its microstructure in response to loading. Based on this form-follows-function relationship, we previously developed a reverse approach to derive joint loads from bone microstructure as acquired with micro-computed tomography. Here, we challenge this approach by calculating hip-joint loading patterns for human and dog, two species exhibiting different locomotion, and comparing them to in vivo measurements. As a proof of concept to use the approach also for extinct taxa, we applied it to a cave lion fossil bone. Calculations were in close agreement with in vivo measurements during walking for extant species, showing distinguished patterns for bipedalism and quadrupedalism. The cave lion calculations clearly revealed its quadrupedal locomotion and suggested a more diverse behaviour compared to the dog, which is in agreement with extant felids. This indicates that our novel approach is potentially useful for making inferences about locomotion in living as well as extinct mammals and to study evolutionary joint development. PMID:24952222

  2. LUBA: an assessment technique for postural loading on the upper body based on joint motion discomfort and maximum holding time.

    PubMed

    Kee, D; Karwowski, W

    2001-08-01

    This paper presents a technique for postural loading on the upper body assessment (LUBA). The proposed method is based on the new experimental data for composite index of perceived discomfort (ratio values) for a set of joint motions, including the hand, arm, neck and back, and the corresponding maximum holding times in static postures. Twenty male subjects participated in the experiment designed to measure perceived joint discomforts. The free modulus technique of the magnitude estimation method was employed to obtain subjects' discomforts for varying joint motions. The developed postural classification scheme was based on the angular deviation levels from the neutral position for each joint motion. These were divided into groups with the same degree of discomforts based on the statistical analysis. Each group was assigned a numerical discomfort score relative to the perceived discomfort value of elbow flexion, which exhibited the lowest level among all joint motions investigated in this study, and, therefore, was set as a reference point. The criteria for evaluating stresses of working postures were proposed based on the four distinct action categories, in order to enable practitioners to apply appropriate corrective actions. The proposed scheme can be used for evaluating and redesigning static working postures in industry. PMID:11461037

  3. First Beam to FACET

    SciTech Connect

    Erickson, R.; Clarke, C.; Colocho, W.; Decker, F.-J.; Hogan, M.; Kalsi, S.; Lipkowitz, N.; Nelson, J.; Phinney, N.; Schuh, P.; Sheppard, J.; Smith, H.; Smith, T.; Stanek, M.; Turner, J.; Warren, J.; Weathersby, S.; Wienands, U.; Wittmer, W.; Woodley, M.; Yocky, G.; /SLAC

    2011-12-13

    The SLAC 3km linear electron accelerator has been reconfigured to provide a beam of electrons to the new Facility for Advanced Accelerator Experimental Tests (FACET) while simultaneously providing an electron beam to the Linac Coherent Light Source (LCLS). On June 23, 2011, the first electron beam was transported through this new facility. Commissioning of FACET is in progress. On June 23, 2011, an electron beam was successfully transported through the new FACET system to a dump in Sector 20 in the linac tunnel. This was achieved while the last third of the linac, operating from the same control room, but with a separate injector system, was providing an electron beam to the Linac Coherent Light Source (LCLS), demonstrating that concurrent operation of the two facilities is practical. With the initial checkout of the new transport line essentially complete, attention is now turning toward compressing the electron bunches longitudinally and focusing them transversely to support a variety of accelerator science experiments.

  4. [The dark side of facet joint].

    PubMed

    Barelli, Laurence Perrin; Dettori, Nadia Guzman

    2016-06-22

    Low back pain (LBP) is a major medical and economical problem, because of its high incidence. Indeed, 70-85% of adult people will suffer from this kind of pain once in their life. We will focus in this article on chronic LBP, which represent an annual prevalence of 30% and more specifically on mechanical pain, with our without radiation into the legs. In case of failure of traditional analgesia combining drugs and physical therapies, we can propose interventional pain relief. This involves a series of diagnostic blocks (medial branch blocks), followed by the treatment (radiofrequency ablation). This treatment remains purely symptomatic. A multidisciplinary approach with patient's physical reconditioning is therefore very important. PMID:27506065

  5. The use of a constant load to generate equivalent viscoelastic strain in finite element analysis of cemented prosthetic joints subjected to cyclic loading.

    PubMed

    Lu, Z; McKellop, H A

    2011-08-01

    Polymers such as polymethyl-methacrylate (PMMA) surgical cement undergo elastic and viscoelastic deformation (creep) in response to physiological cyclic loading. Theoretically, the effect of gradual creep deformation on the stresses, strains, and displacements of a prosthetic joint can be evaluated by running a finite element analysis (FEA) model through a large number of loading cycles. However, with complex (i.e. realistic) models, this approach may require extensive computational time, and may accumulate unacceptably large numerical errors over the many iterations of the model. The present study utilized a Fourier series to represent a periodic stress and incorporated it in the linear viscoelastic constitutive equation. It was demonstrated that, for a linear viscoelastic material, the time average (i.e. the constant in the Fourier series) of the cyclic stress determined the accumulated creep strain and the sinusoidal components of the stress produced the periodic creep strain with a zero average and negligible amplitude. For a geometrically linear FEA model, the solution based on a cyclic stress can be readily applied to an external cyclic load, that is, the creep strain is determined by the time average of the cyclic load. While femoral component models were considered as geometrically non-linear, an FEA model of a femur implanted with an Exeter hip prosthesis showed that there was only a minor difference between the profile of the applied sinusoidal load and that of the resulting displacement. In such cases, applying the time average of a cyclic load to calculate the resulting creep strain with a given duration of loading should expect to provide acceptable accuracy, with a marked reduction in the computational time. PMID:21922957

  6. SLAC All Access: FACET

    ScienceCinema

    Hogan, Mark

    2014-09-15

    SLAC's Facility for Advanced Accelerator Experimental Tests, or FACET, is a test-bed where researchers are developing the technologies required for particle accelerators of the future. Scientists from all over the world come to explore ways of improving the power and efficiency of the particle accelerators used in basic research, medicine, industry and other areas important to society. In this video, Mark Hogan, head of SLAC's Advanced Accelerator Research Department, offers a glimpse into FACET, which uses part of SLAC's historic two-mile-long linear accelerator.

  7. SLAC All Access: FACET

    SciTech Connect

    Hogan, Mark

    2012-07-05

    SLAC's Facility for Advanced Accelerator Experimental Tests, or FACET, is a test-bed where researchers are developing the technologies required for particle accelerators of the future. Scientists from all over the world come to explore ways of improving the power and efficiency of the particle accelerators used in basic research, medicine, industry and other areas important to society. In this video, Mark Hogan, head of SLAC's Advanced Accelerator Research Department, offers a glimpse into FACET, which uses part of SLAC's historic two-mile-long linear accelerator.

  8. Facets of Subjectification

    ERIC Educational Resources Information Center

    Visconti, Jacqueline

    2013-01-01

    Subjectification, as the diachronic facet of subjectivity, has raised in the last two decades a number of interesting questions in grammaticalization and semantic change theory. In this paper I shall reflect on the nature and construal of subjectification, focusing on the question, formulated by Traugott (2010a, p. 58), "whether it is possible to…

  9. Beam Diagnostics for FACET

    SciTech Connect

    Li, S.Z.; Hogan, M.J.; /SLAC

    2011-08-19

    FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration beginning in summer 2011. The nominal FACET parameters are 23GeV, 3nC electron bunches compressed to about 20 {micro}m long and focussed to about 10 {micro}m wide. Characterization of the beam-plasma interaction requires complete knowledge of the incoming beam parameters on a pulse-to-pulse basis. FACET diagnostics include Beam Position Monitors, Toroidal current monitors, X-ray and Cerenkov based energy spectrometers, optical transition radiation (OTR) profile monitors and coherent transition radiation (CTR) bunch length measurement systems. The compliment of beam diagnostics and their expected performance are reviewed. Beam diagnostic measurements not only provide valuable insights to the running and tuning of the accelerator but also are crucial for the PWFA experiments in particular. Beam diagnostic devices are being set up at FACET and will be ready for beam commissioning in summer 2011.

  10. Craniovertebral Junction Instability: A Review of Facts about Facets

    PubMed Central

    2015-01-01

    Craniovertebral junction surgery involves an appropriate philosophical, biomechanical and anatomical understanding apart from high degree of technical skill and ability of controlling venous and arterial bleeding. The author presents his 30-year experience with treating complex craniovertebral junction instability related surgical issues. The facets of atlas and axis form the primary site of movements at the craniovertebral junction. All craniovertebral junction instability is essentially localized to the atlantoaxial facet joint. Direct manipulation and fixation of the facets forms the basis of treatment for instability. PMID:26240728

  11. Load transfer in the stiffener-to-skin joints of a pressurized fuselage

    NASA Technical Reports Server (NTRS)

    Johnson, Eric R.; Rastogi, Naveen

    1995-01-01

    Structural analyses are developed to determine the linear elastic and the geometrically nonlinear elastic response of an internally pressurized, orthogonally stiffened, composite material cylindrical shell. The configuration is a long circular cylindrical shell stiffened on the inside by a regular arrangement of identical stringers and identical rings. Periodicity permits the analysis of a unit cell model consisting of a portion of the shell wall centered over one stringer-ring joint. The stringer-ring-shell joint is modeled in an idealized manner; the stiffeners are mathematically permitted to pass through one another without contact, but do interact indirectly through their mutual contact with the shell at the joint. Discrete beams models of the stiffeners include a stringer with a symmetrical cross section and a ring with either a symmetrical or an asymmetrical open section. Mathematical formulations presented for the linear response include the effect of transverse shear deformations and the effect of warping of the ring's cross section due to torsion. These effects are important when the ring has an asymmetrical cross section because the loss of symmetry in the problem results in torsion and out-of-plane bending of the ring, and a concomitant rotation of the joint at the stiffener intersection about the circumferential axis. Data from a composite material crown panel typical of a large transport fuselage structure are used for two numerical examples. Although the inclusion of geometric nonlinearity reduces the 'pillowing' of the shell, it is found that bending is localized to a narrow region near the stiffener. Including warping deformation of the ring into the analysis changes the sense of the joint rotation. Transverse shear deformation models result in increased joint flexibility.

  12. Facet-selective photodeposition of gold nanoparticles on faceted ZnO crystals for visible light photocatalysis.

    PubMed

    Wang, Xuewen; Wang, Wuyou; Miao, Yuanquan; Feng, Gang; Zhang, Rongbin

    2016-08-01

    Hexagonal prism-like ZnO crystals dominated with polar facets were synthesized using a hydrothermal method. The Gold (Au) nanoparticles were selectively photodeposited on the polar surfaces of faceted ZnO crystals as a result of anisotropic photocatalytic activities of the polar and nonpolar facets. The size of Au nanoparticles uniformly dispersed on the polar facets increased with increasing Au-loading amount. These Au-loaded ZnO crystals showed an additional visible light absorption band from 400nm to 800nm. The 0.1wt% Au-loaded ZnO crystals with visible light absorption peak at approximately 690nm exhibited the highest photocatalytic activity under visible light irradiation. PMID:27156091

  13. The Evolution of Male-Biased Dispersal under the Joint Selective Forces of Inbreeding Load and Demographic and Environmental Stochasticity.

    PubMed

    Henry, Roslyn C; Coulon, Aurélie; Travis, Justin M J

    2016-10-01

    Sex-biased natal dispersal is widespread, and its significance remains a central question in evolutionary biology. However, theory so far fails to predict some of the most common patterns found in nature. To address this, we present novel results from an individual-based model investigating the joint roles of inbreeding load, demographic stochasticity, environmental stochasticity, and dispersal costs for the evolution of sex-biased dispersal. Most strikingly, we found that male-biased natal dispersal evolved in polygynous systems as a result of the interplay between inbreeding avoidance and stochasticity, whereas previous theory, in contrast to empirical observations, predicted male philopatry and female-biased natal dispersal under inbreeding load alone. Furthermore, the direction of the bias varied according to the nature of stochasticity. Our results therefore provide a unification of previous theory, yielding a much better qualitative match with empirical observations of male-biased dispersal in mate defense mating systems. PMID:27622876

  14. An automatic closed-loop control system of boiler load for combined joint and separate combustion of gases

    NASA Astrophysics Data System (ADS)

    Ismatkhodzhaev, S. K.

    2014-10-01

    A system for automatic closed-loop control of drum boiler heat load for combined joint and separate combustion of blast-furnace, coke, and natural gases under the conditions of randomly changed flow rates of blast-furnace and coke gases is considered. For achieving more efficient operation of the automatic control system, it is proposed to introduce circuits for compensating random disturbances in the flow rates of these gases in addition to the standard automatic control system using the heat signal. The estimated parameters of the control channels transfer functions are presented for different ratios between the flow rates of fired gases and boiler loads. The results obtained from an investigation of the combined system are described, and its effectiveness with the boiler operating in different modes is demonstrated.

  15. FACET Emittance Growth

    SciTech Connect

    Frederico, J; Hogan, M.J.; Nosochkov, Y.; Litos, M.D.; Raubenheimer, T.; /SLAC

    2011-04-05

    FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration. The FACET beamline consists of a chicane and final focus system to compress the 23 GeV, 3.2 nC electron bunches to {approx}20 {micro}m long and {approx}10 {micro}m wide. Simulations of the FACET beamline indicate the short-duration and large, 1.5% rms energy spread beams may suffer a factor of four emittance growth from a combination of chromaticity, incoherent synchrotron radiation (ISR), and coherent synchrotron radiation (CSR). Emittance growth is directly correlated to head erosion in plasma wakefield acceleration and is a limiting factor in single stage performance. Studies of the geometric, CSR, and ISR components are presented. Numerical calculation of the rms emittance can be overwhelmed by long tails in the simulated phase space distributions; more useful definitions of emittance are given. A complete simulation of the beamline is presented as well, which agrees with design specifications.

  16. LOFAR Facet Calibration

    NASA Astrophysics Data System (ADS)

    van Weeren, R. J.; Williams, W. L.; Hardcastle, M. J.; Shimwell, T. W.; Rafferty, D. A.; Sabater, J.; Heald, G.; Sridhar, S. S.; Dijkema, T. J.; Brunetti, G.; Brüggen, M.; Andrade-Santos, F.; Ogrean, G. A.; Röttgering, H. J. A.; Dawson, W. A.; Forman, W. R.; de Gasperin, F.; Jones, C.; Miley, G. K.; Rudnick, L.; Sarazin, C. L.; Bonafede, A.; Best, P. N.; Bîrzan, L.; Cassano, R.; Chyży, K. T.; Croston, J. H.; Ensslin, T.; Ferrari, C.; Hoeft, M.; Horellou, C.; Jarvis, M. J.; Kraft, R. P.; Mevius, M.; Intema, H. T.; Murray, S. S.; Orrú, E.; Pizzo, R.; Simionescu, A.; Stroe, A.; van der Tol, S.; White, G. J.

    2016-03-01

    LOFAR, the Low-Frequency Array, is a powerful new radio telescope operating between 10 and 240 MHz. LOFAR allows detailed sensitive high-resolution studies of the low-frequency radio sky. At the same time LOFAR also provides excellent short baseline coverage to map diffuse extended emission. However, producing high-quality deep images is challenging due to the presence of direction-dependent calibration errors, caused by imperfect knowledge of the station beam shapes and the ionosphere. Furthermore, the large data volume and presence of station clock errors present additional difficulties. In this paper we present a new calibration scheme, which we name facet calibration, to obtain deep high-resolution LOFAR High Band Antenna images using the Dutch part of the array. This scheme solves and corrects the direction-dependent errors in a number of facets that cover the observed field of view. Facet calibration provides close to thermal noise limited images for a typical 8 hr observing run at ∼ 5\\prime\\prime resolution, meeting the specifications of the LOFAR Tier-1 northern survey.

  17. Comparison of computed tomography and magnetic resonance imaging in the evaluation of facet tropism and facet arthrosis in degenerative cervical spondylolisthesis.

    PubMed

    Xu, C; Ding, Z H; Xu, Y K

    2014-01-01

    The aim of this study was to determine the reliability of magnetic resonance imaging (MRI) in the assessment of facet tropism and facet arthrosis of spondylolisthesis levels in degenerative cervical spondylolisthesis as compared to computed tomography (CT). The discrepancies in the interpretation of CT and MRI data in the evaluation of facet tropism and arthrosis have given rise to questions regarding the reliability of comparisons of the two techniques. Using a 4-point scale, 3 blinded readers independently graded the severity of facet tropism and facet arthrosis of 79 cervical facet joints on axial T2-weighted and sagittal T1 and T2-weighted turbo spin echo images as well as the corresponding axial CT scans. All results were subjected to the kappa coefficient statistic for strength of agreement. In the assessment of the severity of facet arthrosis, intermethod agreement (weighted κ) between CT scanning with a moderate inter-rater reliability (range κ = 0.43-0.57) and MRI with fair inter-rater reliability (range κ = 0.23-0.38) was 0.76 and 0.43 for the severity of facet tropism and facet arthrosis, respectively. Intra-rater reliability for the severity of facet arthrosis was moderate to substantial for CT and was moderate for MRI scans. Intra-rater reliability for the severity of facet tropism was substantial to very good for CT and substantial for MRI scans. MRI can reliably determine the presence or degree of facet tropism but not facet arthrosis. Therefore, for a comprehensive assessment of cervical facet joint degeneration, both a CT and an MRI scan should be performed. PMID:24938702

  18. Effects of Microstructure and Loading on Fracture of Sn-3.8Ag-0.7Cu Joints on Cu Substrates with ENIG Surface Finish

    NASA Astrophysics Data System (ADS)

    Huang, Z.; Kumar, P.; Dutta, I.; Sidhu, R.; Renavikar, M.; Mahajan, R.

    2014-12-01

    When dropped, electronic packages often undergo failure by propagation of an interfacial crack in solder joints under a combination of tensile and shear loading. Hence, it is crucial to understand and predict the fracture behavior of solder joints under mixed-mode high-rate loading conditions. In this work, the effects of the loading conditions (strain rate and loading angle) and microstructure [interfacial intermetallic compound (IMC) morphology and solder yield strength] on the mixed-mode fracture toughness of Sn-3.8 wt.%Ag-0.7 wt.%Cu solder joints sandwiched between two Cu substrates with electroless nickel immersion gold (ENIG) metallization have been studied, and compared with the fracture behavior of joints attached to bare Cu. Irrespective of the surface finish, the fracture toughness of the solder joints decreased monotonically with strain rate and mode-mixity, both resulting in increased fracture proportion through the interfacial IMC layer. Furthermore, the proportion of crack propagation through the interfacial IMC layer increased with increase in the thickness and the roughness of the interfacial IMC layer and the yield strength of the solder, resulting in a decrease in the fracture toughness of the joint. However, under most conditions, solder joints with ENIG finish showed higher resistance to fracture than joints attached directly to Cu substrates without ENIG metallization. Based on the experimental observations, a fracture mechanism map is constructed correlating the yield strength of the solder, the morphology and thickness of the interfacial IMC, and the fracture mechanisms as well as the fracture toughness values for different solder joints under mode I loading.

  19. Compromised encoding of proprioceptively determined joint angles in older adults: the role of working memory and attentional load.

    PubMed

    Goble, Daniel J; Mousigian, Marianne A; Brown, Susan H

    2012-01-01

    Perceiving the positions and movements of one's body segments (i.e., proprioception) is critical for movement control. However, this ability declines with older age as has been demonstrated by joint angle matching paradigms in the absence of vision. The aim of the present study was to explore the extent to which reduced working memory and attentional load influence older adult proprioceptive matching performance. Older adults with relatively HIGH versus LOW working memory ability as determined by backward digit span and healthy younger adults, performed memory-based elbow position matching with and without attentional load (i.e., counting by 3 s) during target position encoding. Even without attentional load, older adults with LOW digit spans (i.e., 4 digits or less) had larger matching errors than younger adults. Further, LOW older adults made significantly greater errors when attentional loads were present during proprioceptive target encoding as compared to both younger and older adults with HIGH digit span scores (i.e., 5 digits or greater). These results extend previous position matching results that suggested greater errors in older adults were due to degraded input signals from peripheral mechanoreceptors. Specifically, the present work highlights the role cognitive factors play in the assessment of older adult proprioceptive acuity using memory-based matching paradigms. Older adults with LOW working memory appear prone to compromised proprioceptive encoding, especially when secondary cognitive tasks must be concurrently executed. This may ultimately result in poorer performance on various activities of daily living. PMID:22006273

  20. The pizzicato knee-joint energy harvester: characterization with biomechanical data and the effect of backpack load

    NASA Astrophysics Data System (ADS)

    Pozzi, Michele; Aung, Min S. H.; Zhu, Meiling; Jones, Richard K.; Goulermas, John Y.

    2012-07-01

    The reduced power requirements of miniaturized electronics offer the opportunity to create devices which rely on energy harvesters for their power supply. In the case of wearable devices, human-based piezoelectric energy harvesting is particularly difficult due to the mismatch between the low frequency of human activities and the high-frequency requirements of piezoelectric transducers. We propose a piezoelectric energy harvester, to be worn on the knee-joint, that relies on the plucking technique to achieve frequency up-conversion. During a plucking action, a piezoelectric bimorph is deflected by a plectrum; when released due to loss of contact, the bimorph is free to vibrate at its resonant frequency, generating electrical energy with the highest efficiency. A prototype, featuring four PZT-5H bimorphs, was built and is here studied in a knee simulator which reproduces the gait of a human subject. Biomechanical data were collected with a marker-based motion capture system while the subject was carrying a selection of backpack loads. The paper focuses on the energy generation of the harvester and how this is affected by the backpack load. By altering the gait, the backpack load has a measurable effect on performance: at the highest load of 24 kg, a minor reduction in energy generation (7%) was observed and the output power is reduced by 10%. Both are so moderate to be practically unimportant. The average power output of the prototype is 2.06 ± 0.3 mW, which can increase significantly with further optimization.

  1. Changes in the Structure and Properties of Welded Joints of Low-Alloy Steels, Subjected to Cyclic Loads

    NASA Astrophysics Data System (ADS)

    Kuskov, V. N.; Kovenskiy, I. M.; Kuskov, K. V.

    2016-04-01

    Time-varying loads negatively affect the properties and structure of materials. Structural failures typically occur at loads below the yield point. In this work, fatigue tests of welded joints of low-alloy steels were carried out in an asymmetric cycle at loads of 60 and 80% of the yield strength. The stress ratio was 0.8-0.9. On the basis of the results of the tests, equations linking the number of cycles to failure with test parameters were obtained. Such equations can be used for estimating the residual life of elements both under construction and in operation. It has been found that the failure is not instantaneous. Specimens of steels continue to resist variable loads for 4000 - 26000 cycles to failure, depending on steel grade and the parameters of the test. Under operating conditions, it gives an opportunity to discover the onset of failure and dispose of the defective part or to replace the entire structure. A standard technique was used to measure the microhardness on the fractured specimens. The distance between the nearest indentations was 0.2 mm. The results of the measurements were plotted in graphs of ahardness change characteristic for all steels under study. A microhardness “step” has been discovered in areas with high dislocation density, as evidenced by x-ray diffraction and transmission electron microscopy. An intermediate stage of the investigation is the development of recommendations for determining the moment of failure of welded constructions with a probability of 95%.

  2. Effects of Anterior-Posterior Constraint on Injury Patterns in the Human Knee During Tibial-Femoral Joint Loading from Axial Forces through the Tibia.

    PubMed

    Jayaraman, V M; Sevensma, E T; Kitagawa, M; Haut, R C

    2001-11-01

    According to the National Accident Sampling System (NASS), 10% of all automobile accident injuries involve the knee. These injuries involve bone fracture and/or "soft tissue" injury. Previous investigators have determined the tibial-femoral (TF) joint failure load for an experimentally constrained human knee at 90 degrees flexion. In these experiments bone fractures have been documented. During TF joint compression, however, anterior motion of the tibia has been noted by others. It was therefore the objectives of this study to document effects of flexion angle and anterior-posterior joint constraint on the nature and severity of knee injury during TF compression loading via axial loads in the tibia. The effect of flexion angle was examined using 10 unconstrained human knees from 5 cadavers aged 73.2+/-9.4 years. The tibial-femoral joint was loaded in compression as a result of axial loading along the tibia using a servo-hydraulic testing machine until gross failure with the knee flexed 60 degrees or 120 degrees . Pressure sensitive film measured the distribution of internal TF joint loads. Both 60 degrees and 120 degrees flexed preparations failed by rupture of the anterior cruciate ligament (ACL) at 4.6+/-1.2 kN, and the internal joint loads were significantly higher (2.6+/-1.5 kN) on the medial versus the lateral (0.4+/-0.5 kN) aspect of the tibial plateau. The effect of anterior-posterior (AP) constraint of the femur along the longitudinal axis of the femur was investigated in a second series of tests using the same TF joint loading protocol on 6 pairs of human joints (74.3+/-10.5 years) flexed at 90 degrees . The primary mode of failure for the AP constrained joints was fracture of bone via the femoral condyle at a maximum load of 9.2+/-2.6 kN. The mode of failure for unconstrained joints was primarily due to rupture of the ACL at a maximum load of 5.8+/-2.9 kN. Again, the pressure film indicated an unequal internal TF load distribution for the unconstrained

  3. An in Silico Analysis of Ankle Joint Loads in Secondary Ankle Osteoarthritis. Case Study.

    PubMed

    Lorkowski, Jacek; Mrzygłód, Mirosław W; Grzegorowska, Oliwia; Kotela, Ireneusz

    2015-01-01

    Secondary, post-traumatic, degenerative lesions of the ankle joint remain a serious clinical challenge. This paper presents the case of a 66-year-old patient with secondary, post-traumatic ankle osteoarthritis and subchondral cysts. The use of rapid computer modelling FEM 2D enabled optimization of surgical treatment. A FEM 2D model of biomechanical changes in bones may help in streamlining treatment as well as improve our understanding of the pathomechanism of osteoarthritis. PMID:26248632

  4. "In vivo" determination of hip joint separation and the forces generated due to impact loading conditions.

    PubMed

    Dennis, D A; Komistek, R D; Northcut, E J; Ochoa, J A; Ritchie, A

    2001-05-01

    Numerous supporting structures assist in the retention of the femoral head within the acetabulum of the normal hip joint including the capsule, labrum, and ligament of the femoral head (LHF). During total hip arthroplasty (THA), the LHF is often disrupted or degenerative and is surgically removed. In addition, a portion of the remaining supporting structures is transected or resected to facilitate surgical exposure. The present study analyzes the effects of LHF absence and surgical dissection in THA patients. Twenty subjects (5 normal hip joints, 10 nonconstrained THA, and 5 constrained THA) were evaluated using fluoroscopy while performing active hip abduction. All THA subjects were considered clinically successful. Fluoroscopic videos of the normal hips were analyzed using digitization, while those with THA were assessed using a computerized interactive model-fitting technique. The distance between the femoral head and acetabulum was measured to determine if femoral head separation occurred. Error analysis revealed measurements to be accurate within 0.75mm. No separation was observed in normal hips or those subjects implanted with constrained THA, while all 10 (100%) with unconstrained THA demonstrated femoral head separation, averaging 3.3mm (range 1.9-5.2mm). This study has shown that separation of the prosthetic femoral head from the acetabular component can occur. The normal hip joint has surrounding capsuloligamentous structures and a ligament attaching the femoral head to the acetabulum. We hypothesize that these soft tissue supports create a passive, resistant force at the hip, preventing femoral head separation. The absence of these supporting structures after THA may allow increased hip joint forces, which may play a role in premature polyethylene wear or prosthetic loosening. PMID:11311703

  5. Stress analysis method for clearance-fit joints with bearing-bypass loads

    NASA Technical Reports Server (NTRS)

    Naik, R. A.; Crews, J. H., Jr.

    1989-01-01

    A simple direct stress analysis method is proposed for a laminate with a clearance-fit fastener subjected to combined bearing and bypass loads in tension or compression, including bearing and bypass loads on bolt-hole contact and local stresses. The approach uses a linear-elastic finite element analysis with an inverse formulation; conditions along the bolt-hole interface are specified by constraint equations that limit nodal displacements to a circular arc corresponding to the bolt diameter. The application of the method to the analysis of the effects of bearing-bypass loading on bolt-hole contact angles and local stresses, with the plate material properties representing a quasi-isotropic T300/5208 graphite/epoxy laminate, is discussed.

  6. Investigation of impact loading rate effects on the ligamentous cervical spinal load-partitioning using finite element model of functional spinal unit C2-C3.

    PubMed

    Mustafy, Tanvir; El-Rich, Marwan; Mesfar, Wissal; Moglo, Kodjo

    2014-09-22

    The cervical spine functions as a complex mechanism that responds to sudden loading in a unique manner, due to intricate structural features and kinematics. The spinal load-sharing under pure compression and sagittal flexion/extension at two different impact rates were compared using a bio-fidelic finite element (FE) model of the ligamentous cervical functional spinal unit (FSU) C2-C3. This model was developed using a comprehensive and realistic geometry of spinal components and material laws that include strain rate dependency, bone fracture, and ligament failure. The range of motion, contact pressure in facet joints, failure forces in ligaments were compared to experimental findings. The model demonstrated that resistance of spinal components to impact load is dependent on loading rate and direction. For the loads applied, stress increased with loading rate in all spinal components, and was concentrated in the outer intervertebral disc (IVD), regions of ligaments to bone attachment, and in the cancellous bone of the facet joints. The highest stress in ligaments was found in capsular ligament (CL) in all cases. Intradiscal pressure (IDP) in the nucleus was affected by loading rate change. It increased under compression/flexion but decreased under extension. Contact pressure in the facet joints showed less variation under compression, but increased significantly under flexion/extension particularly under extension. Cancellous bone of the facet joints region was the only component fractured and fracture occurred under extension at both rates. The cervical ligaments were the primary load-bearing component followed by the IVD, endplates and cancellous bone; however, the latter was the most vulnerable to extension as it fractured at low energy impact. PMID:25129167

  7. Energy expended and knee joint load accumulated when walking, running, or standing for the same amount of time.

    PubMed

    Miller, Ross H; Edwards, W Brent; Deluzio, Kevin J

    2015-01-01

    Evidence suggests prolonged bouts of sitting are unhealthy, and some public health messages have recently recommended replacing sitting with more standing. However, the relative benefits of replacing sitting with standing compared to locomotion are not known. Specifically, the biomechanical consequences of standing compared to other sitting-alternatives like walking and running are not well known and are usually not considered in studies on sitting. We compared the total knee joint load accumulated (TKJLA) and the total energy expended (TEE) when performing either walking, running, or standing for a common exercise bout duration (30 min). Walking and running both (unsurprisingly) had much more TEE than standing (+300% and +1100%, respectively). TKJLA was similar between walking and standing and 74% greater in running. The results suggest that standing is a poor replacement for walking and running if one wishes to increases energy expenditure, and may be particularly questionable for use in individuals at-risk for knee osteoarthritis due to its surprisingly high TKJLA (just as high as walking, 56% of the load in running) and the type of loading (continuous compression) it places on cartilage. However, standing has health benefits as an "inactivity interrupter" that extend beyond its direct energy expenditure. We suggest that future studies on standing as an inactivity intervention consider the potential biomechanical consequences of standing more often throughout the day, particularly in the case of prolonged bouts of standing. PMID:25455208

  8. Loads on Sprayed Waterproof Tunnel Linings in Jointed Hard Rock: A Study Based on Norwegian Cases

    NASA Astrophysics Data System (ADS)

    Holter, Karl Gunnar

    2014-05-01

    A composite tunnel lining system based on a sprayed waterproofing membrane combined with sprayed concrete is currently being considered for future Norwegian rail and road tunnels. Possible loading of the tunnel linings caused by water pressure is being investigated. This tunnel lining system consists of a waterproof membrane which, during application on the sprayed concrete lining, bonds mechanically to the sprayed concrete on either side. Hence, a continuous, sealing, and non-draining structure from the rock mass to the interior tunnel surface is formed in the walls and crown. Experiences from some successful recent projects with this lining system in Europe are reviewed. However, these experiences are not directly comparable to the Scandinavian hard rock tunnel lining approach, which utilizes a relatively thin sprayed and irregular concrete layer for permanent lining. When considering the sprayed membrane and sprayed concrete composite lining concept, introducing a partially sealing and undrained element in the lining, the experiences with the traditionally used lining systems in Norway need to be reconsidered and fully understood. A review of several hard rock tunnels with adverse conditions, in which the tunnel lining has been subject to load monitoring, shows that only very small loads in the tunnel linings occur. Recent investigations with in situ water pressure testing, including two sites with the composite sprayed membrane in a partially drained waterproof tunnel lining, are discussed. In a case with a cavern located in a hydraulically saturated rock mass subjected to approximately 8 bar hydrostatic pressure, a negative pressure gradient towards the tunnel lining has been measured. The investigation results from the Norwegian test sites indicate that no significant loading of the tunnel lining takes place in a hydraulically saturated rock when applying this composite waterproof tunnel lining in parts of the tunnel perimeter.

  9. Lubrication of metal-on-metal hip joints: the effect of protein content and load on film formation and wear.

    PubMed

    Myant, C; Underwood, R; Fan, J; Cann, P M

    2012-02-01

    Lubricant films were measured for a series of bovine serum and protein containing (albumin, globulin) saline solutions for CoCrMo femoral component sliding against a glass disc. Central film thickness was measured by optical interferometry as a function of time (constant mean speed: 0 and 10 mm/s) and variable mean speed (0-50 mm/s). The effect of load (5-20 N) on film thickness was also studied. The development of the wear scar on the CoCrMo surface was monitored by measuring the width of the contact zone during the film thickness tests. The results showed film thickness increased with time for both the static and sliding tests. Films formed in the static, loaded test were typically in the range of 3-40 nm. The globulin containing solutions formed the thickest films. In the sliding tests a wear scar rapidly formed on the implant component for the bovine serum and albumin fluids, negligible wear was observed for the globulin solutions. Film thickness increased with sliding time for all test solutions and was much greater than predicted by isoviscous EHL models. The film increase was found to correlate with increasing wear scar size and thus decreasing contact pressure. A new lubricating mechanism is proposed whereby during sliding the fluid undergoes bulk phase separation rheology, so that an elevated protein phase forms in the inlet zone. This protein phase is a high-viscosity biphasic matrix, which is periodically entrained into the contact forming a thick protective hydro-gel film. One of the main findings of this study is that film thickness was very sensitive to load; to a much greater extent than predicted by EHL models. Thus film formation in MoM hip joints is very susceptible to high contact pressures which might be due to implant misalignment and edge-loading. PMID:22301171

  10. Load compensating reactions to perturbations at wrist joint in normal man

    NASA Technical Reports Server (NTRS)

    Jaeger, R. J.; Agarwell, G. C.; Gottlieb, G. L.

    1981-01-01

    The electromyographic responses to step torque loads were studied in flexors and extensors at the human wrist. Based on temporal bursting patterns and functional behavior, the response was divided into four temporal components. Two early components, the myotatic (30-60 ms) late myotatic (60-120 ms) appears to be reflex response. The third postmyotatic component (120-200 ms) appear to be a triggered reaction, preceeding the fourth, stabilizing component (200-400 ms). A comparison of response at the wrist with similar data at the ankle provides the basis for a generalized classification of the response in various muscles to torque step perturbations.

  11. Wear Testing of Moderate Activities of Daily Living Using In Vivo Measured Knee Joint Loading

    PubMed Central

    Reinders, Jörn; Sonntag, Robert; Vot, Leo; Gibney, Christian; Nowack, Moritz; Kretzer, Jan Philippe

    2015-01-01

    Resumption of daily living activities is a basic expectation for patients provided with total knee replacements. However, there is a lack of knowledge regarding the impact of different activities on the wear performance. In this study the wear performance under application of different daily activities has been analyzed. In vivo load data for walking, walking downstairs/upstairs, sitting down/standing up, and cycling (50 W & 120 W) has been standardized for wear testing. Wear testing of each activity was carried out on a knee wear simulator. Additionally, ISO walking was tested for reasons of comparison. Wear was assessed gravimetrically and wear particles were analyzed. In vivo walking produced the highest overall wear rates, which were determined to be three times higher than ISO walking. Moderate wear rates were determined for walking upstairs and downstairs. Low wear rates were determined for standing up/sitting down and cycling at power levels of 50 W and 120 W. The largest wear particles were observed for cycling. Walking based on in vivo data has been shown to be the most wear-relevant activity. Highly demanding activities (stair climbing) produced considerably less wear. Taking into account the expected number of loads, low-impact activities like cycling may have a greater impact on articular wear than highly demanding activities. PMID:25811996

  12. Effect of adherend thickness and mixed mode loading on debond growth in adhesively bonded composite joints

    NASA Technical Reports Server (NTRS)

    Mangalgiri, P. D.; Johnson, W. S.; Everett, R. A., Jr.

    1986-01-01

    Symmetric and unsymmetric double cantilever beam (DCB) specimens were tested and analyzed to assess the effect of: (1) adherend thickness, and (2) a predominantly mode I mixed mode loading on cyclic debond growth and static fracture toughness. The specimens were made of unidirectional composite (T300/5208) adherends bonded together with EC3445 structural adhesive. The thickness was 8, 16, or 24 plies. The experimental results indicated that the static fracture toughness increases and the cyclic debond growth rate decreases with increasing adherend thickness. This behavior was related to the length of the plastic zone ahead of the debond tip. For the symmetric DCB specimens, it was further found that displacement control tests resulted in higher debond growth rates than did load control tests. While the symmetric DCB tests always resulted in cohesive failures in the bondline, the unsymmetric DCB tests resulted in the debond growing into the thinner adherend and the damage progressing as delamination in that adherend. This behavior resulted in much lower fracture toughness and damage growth rates than found in the symmetric DCB tests.

  13. A new approach to implant alignment and ligament balancing in total knee arthroplasty focussing on joint loads.

    PubMed

    Zimmermann, Frauke; Schwenninger, Christoph; Nolten, Ulrich; Firmbach, Franz Peter; Elfring, Robert; Radermacher, Klaus

    2012-08-01

    Preservation and recovery of the mechanical leg axis as well as good rotational alignment of the prosthesis components and well-balanced ligaments are essential for the longevity of total knee arthroplasty (TKA). In the framework of the OrthoMIT project, the genALIGN system, a new navigated implantation approach based on intra-operative force-torque measurements, has been developed. With this system, optical or magnetic position tracking as well as any fixation of invasive rigid bodies are no longer necessary. For the alignment of the femoral component along the mechanical axis, a sensor-integrated instrument measures the torques resulting from the deviation between the instrument's axis and the mechanical axis under manually applied axial compression load. When both axes are coaxial, the resulting torques equal zero, and the tool axis can be fixed with respect to the bone. For ligament balancing and rotational alignment of the femoral component, the genALIGN system comprises a sensor-integrated tibial trial inlay measuring the amplitude and application points of the forces transferred between femur and tibia. Hereby, the impact of ligament tensions on knee joint loads can be determined over the whole range of motion. First studies with the genALIGN system, including a comparison with an imageless navigation system, show the feasibility of the concept. PMID:22868781

  14. The Many Facets of PISA

    ERIC Educational Resources Information Center

    Berliner, David C.

    2015-01-01

    Trying to understand PISA is analogous to the parable of the blind men and the elephant. There are many facets of the PISA program, and thus many ways to both applaud and critique this ambitious international program of assessment that has gained enormous importance in the crafting of contemporary educational policy. One of the facets discussed in…

  15. The Movement- and Load-Dependent Differences in the EMG Patterns of the Human Arm Muscles during Two-Joint Movements (A Preliminary Study)

    PubMed Central

    Tomiak, Tomasz; Abramovych, Tetiana I.; Gorkovenko, Andriy V.; Vereshchaka, Inna V.; Mishchenko, Viktor S.; Dornowski, Marcin; Kostyukov, Alexander I.

    2016-01-01

    Slow circular movements of the hand with a fixed wrist joint that were produced in a horizontal plane under visual guidance during conditions of action of the elastic load directed tangentially to the movement trajectory were studied. The positional dependencies of the averaged surface EMGs in the muscles of the elbow and shoulder joints were compared for four possible combinations in the directions of load and movements. The EMG intensities were largely correlated with the waves of the force moment computed for a corresponding joint in the framework of a simple geometrical model of the system: arm - experimental setup. At the same time, in some cases the averaged EMGs exit from the segments of the trajectory restricted by the force moment singular points (FMSPs), in which the moments exhibited altered signs. The EMG activities display clear differences for the eccentric and concentric zones of contraction that are separated by the joint angle singular points (JASPs), which present extreme at the joint angle traces. We assumed that the modeled patterns of FMSPs and JASPs may be applied for an analysis of the synergic interaction between the motor commands arriving at different muscles in arbitrary two-joint movements. PMID:27375496

  16. Facet control of gold nanorods

    DOE PAGESBeta

    Zhang, Qingfeng; Han, Lili; Jing, Hao; Blom, Douglas A.; Lin, Ye; Xin, Huolin L.; Wang, Hui

    2016-01-21

    While great success has been achieved in fine-tuning the aspect ratios and thereby the plasmon resonances of cylindrical Au nanorods, facet control with atomic level precision on the highly curved nanorod surfaces has long been a significantly more challenging task. The intrinsic structural complexity and lack of precise facet control of the nanorod surfaces remain the major obstacles for the atomic-level elucidation of the structure–property relationships that underpin the intriguing catalytic performance of Au nanorods. Here we demonstrate that the facets of single-crystalline Au nanorods can be precisely tailored using cuprous ions and cetyltrimethylammonium bromide as a unique pair ofmore » surface capping competitors to guide the particle geometry evolution during nanorod overgrowth. By deliberately maneuvering the competition between cuprous ions and cetyltrimethylammonium bromide, we have been able to create, in a highly controllable and selective manner, an entire family of nanorod-derived anisotropic multifaceted geometries whose surfaces are enclosed by specific types of well-defined high-index and low-index facets. This facet-controlled nanorod overgrowth approach also allows us to fine-tune the particle aspect ratios while well-preserving all the characteristic facets and geometric features of the faceted Au nanorods. Furthermore, taking full advantage of the combined structural and plasmonic tunability, we have further studied the facet-dependent heterogeneous catalysis on well-faceted Au nanorods using surface-enhanced Raman spectroscopy as an ultrasensitive spectroscopic tool with unique time-resolving and molecular finger-printing capabilities.« less

  17. Facet Control of Gold Nanorods.

    PubMed

    Zhang, Qingfeng; Han, Lili; Jing, Hao; Blom, Douglas A; Lin, Ye; Xin, Huolin L; Wang, Hui

    2016-02-23

    While great success has been achieved in fine-tuning the aspect ratios and thereby the plasmon resonances of cylindrical Au nanorods, facet control with atomic level precision on the highly curved nanorod surfaces has long been a significantly more challenging task. The intrinsic structural complexity and lack of precise facet control of the nanorod surfaces remain the major obstacles for the atomic-level elucidation of the structure-property relationships that underpin the intriguing catalytic performance of Au nanorods. Here we demonstrate that the facets of single-crystalline Au nanorods can be precisely tailored using cuprous ions and cetyltrimethylammonium bromide as a unique pair of surface capping competitors to guide the particle geometry evolution during nanorod overgrowth. By deliberately maneuvering the competition between cuprous ions and cetyltrimethylammonium bromide, we have been able to create, in a highly controllable and selective manner, an entire family of nanorod-derived anisotropic multifaceted geometries whose surfaces are enclosed by specific types of well-defined high-index and low-index facets. This facet-controlled nanorod overgrowth approach also allows us to fine-tune the particle aspect ratios while well-preserving all the characteristic facets and geometric features of the faceted Au nanorods. Taking full advantage of the combined structural and plasmonic tunability, we have further studied the facet-dependent heterogeneous catalysis on well-faceted Au nanorods using surface-enhanced Raman spectroscopy as an ultrasensitive spectroscopic tool with unique time-resolving and molecular finger-printing capabilities. PMID:26795706

  18. Chondrocyte Deformations as a Function of Tibiofemoral Joint Loading Predicted by a Generalized High-Throughput Pipeline of Multi-Scale Simulations

    PubMed Central

    Sibole, Scott C.; Erdemir, Ahmet

    2012-01-01

    Cells of the musculoskeletal system are known to respond to mechanical loading and chondrocytes within the cartilage are not an exception. However, understanding how joint level loads relate to cell level deformations, e.g. in the cartilage, is not a straightforward task. In this study, a multi-scale analysis pipeline was implemented to post-process the results of a macro-scale finite element (FE) tibiofemoral joint model to provide joint mechanics based displacement boundary conditions to micro-scale cellular FE models of the cartilage, for the purpose of characterizing chondrocyte deformations in relation to tibiofemoral joint loading. It was possible to identify the load distribution within the knee among its tissue structures and ultimately within the cartilage among its extracellular matrix, pericellular environment and resident chondrocytes. Various cellular deformation metrics (aspect ratio change, volumetric strain, cellular effective strain and maximum shear strain) were calculated. To illustrate further utility of this multi-scale modeling pipeline, two micro-scale cartilage constructs were considered: an idealized single cell at the centroid of a 100×100×100 μm block commonly used in past research studies, and an anatomically based (11 cell model of the same volume) representation of the middle zone of tibiofemoral cartilage. In both cases, chondrocytes experienced amplified deformations compared to those at the macro-scale, predicted by simulating one body weight compressive loading on the tibiofemoral joint. In the 11 cell case, all cells experienced less deformation than the single cell case, and also exhibited a larger variance in deformation compared to other cells residing in the same block. The coupling method proved to be highly scalable due to micro-scale model independence that allowed for exploitation of distributed memory computing architecture. The method’s generalized nature also allows for substitution of any macro-scale and/or micro

  19. Influence of Combinations of Shoulder, Elbow and Trunk Orientation on Elbow Joint Loads in Youth Baseball Pitchers

    PubMed Central

    Tanaka, Hiroshi; Hayashi, Toyohiko; Inui, Hiroaki; Ninomiya, Hiroki; Muto, Tomoyuki; Nobuhara, Katsuya

    2016-01-01

    Objectives: Shoulder and elbow pain in youth baseball pitchers is a well-recognized phenomenon. Common problems in pitching mechanics that can lead to injury begin with stride foot contact. The purpose of this study was to address the relationships between the combinations of shoulder, elbow and trunk orientation at the instant of stride foot contact and elbow joint loads in youth baseball pitchers. Methods: A total of 143 Japanese male youth baseball pitchers participated in this study after providing written informed consents approved by the hospital’s institutional review board. The procedures to be performed were also explained to their parent(s) or legal guardian(s). Each participant was not currently injured or recovering from an injury at time of testing. For data collection of baseball pitching, a set of 14-mm spherical reflective markers was placed on the skin overlying 34 anatomical landmarks determined. Subsequently, a motion capture three-dimensional automatic digitizing system was used to collect 500-Hz from 7 charge-coupled-device synchronized cameras was set up around the regulation pitching mound in an indoor laboratory. After performing a preparation routine of stretching and warm-up pitching, each player pitch to 5 fastball pitches off the pitching mound to a catcher at the regulation distance of 16 m for youth pitchers. The best pitch thrown for a strike was chosen for kinematic and kinetic analysis. The local coordinate systems were used to calculate 3-dimesional rotation at the trunk, shoulder and elbow using the typical Eulerian sequence. Afterward, the standard inverse dynamic equation was used to estimate resultant joint forces and torques at throwing shoulder and elbow. In order to normalize data between subjects, forces and torques were expressed as percent using body weight and height. A multiple regression analysis was carried out to assess the combined effects of shoulder (external rotation, abduction and horizontal adduction), elbow

  20. SLAC Linac Preparations for FACET

    SciTech Connect

    Erickson, R.; Bentson, L.; Kharakh, D.; Owens, A.; Schuh, P.; Seeman, J.; Sheppard, J.C.; Stanek, M.; Wittmer, W.; Yocky, G.; Wienands, U.; /SLAC

    2011-02-07

    The SLAC 3km linear electron accelerator has been cut at the two-thirds point to provide beams to two independent programs. The last third provides the electron beam for the Linac Coherent Light Source (LCLS), leaving the first two-thirds available for FACET, the new experimental facility for accelerator science and test beams. In this paper, we describe this separation and projects to prepare the linac for the FACET experimental program.

  1. Load transfer through the radiocarpal joint and the effects of partial wrist arthrodesis on carpal bone behaviour: a finite element study.

    PubMed

    Gíslason, M K; Stansfield, B; Bransby-Zachary, M; Hems, T; Nash, D H

    2012-11-01

    A finite element model of the wrist was developed to simulate mechanical changes that occur after surgery of the wrist. After partial arthrodesis, the wrist will experience altered force transmission during loading. Three different types of partial arthrodesis were investigated - radiolunate, radioscaphoid, and radioscapholunate - and compared with the healthy untreated wrist. The results showed that the compressive forces on the radiocarpal joint decreased compared with the untreated wrist with both radiolunate and radioscaphoid fusions. The load transmission through the midcarpal joints varied depending on arthrodesis type. The forces in the extrinsic ligaments decreased with the fusion, most noticeably in the dorsal radiotriquetral ligament, but increased in the dorsal scaphotriquetral ligament. From the results of the study it can be concluded that the radioscapholunate fusion shows the most biomechanically similar behaviour out of the three fusion types compared with the healthy wrist. The modelling described in this paper may be a useful approach to pre-operative planning in wrist surgery. PMID:22457257

  2. A two-dimensional stress analysis of a butt adhesive joint containing circular holes and rigid fillers in an adhesive subjected to a tensile load

    SciTech Connect

    Sawa, Toshiyuki; Nakano, Katsuyuki; Nakano, Yuichi

    1995-11-01

    This study deals with a stress analysis of a butt adhesive joint which contains circular holes and rigid fillers in the adhesive and is subjected to a tensile load. In the analysis, the adherends are assumed to be rigid and the adhesive is replaced with a finite strip having holes and rigid fillers in it and the stress distribution in the joint is analyzed using a two-dimensional theory of elasticity. The effects of size and locations of rigid fillers and circular holes on the stress distributions at the interface and around the fillers and holes are clarified by numerical calculations. For verification, photoelastic experiments are performed using an epoxide resin plate modeled as an adhesive in the joint. The analytical results are in fairly good agreement with the experimental ones. In addition, the stress singularity at the edge of the interface is discussed.

  3. Faceting diagram for sticky steps

    NASA Astrophysics Data System (ADS)

    Akutsu, Noriko

    2016-03-01

    Faceting diagrams for the step-faceting zone, the step droplet zone, and the Gruber-Mullins-Pokrovsky-Talapov (GMPT) zone for a crystal surface are obtained by using the density matrix renormalization group method to calculate the surface tension. The model based on these calculations is the restricted solid-on-solid (RSOS) model with a point-contact-type step-step attraction (p-RSOS model) on a square lattice. The point-contact-type step-step attraction represents the energy gain obtained by forming a bonding state with orbital overlap at the meeting point of the neighboring steps. In the step-faceting zone, disconnectedness in the surface tension leads to the formation of a faceted macrostep on a vicinal surface at equilibrium. The disconnectedness in the surface tension also causes the first-order shape transition for the equilibrium shape of a crystal droplet. The lower zone boundary line (ZBL), which separates the step-faceting zone and the step droplet zone, is obtained by the condition γ 1 = lim n → ∞ γ n / n , where γn is the step tension of the n-th merged step. The upper ZBL, which separates the GMPT zone and the step droplet zone, is obtained by the condition Aq,eff = 0 and Bq,eff = 0, where Aq,eff and Bq,eff represent the coefficients for the | q → | 2 term and the | q → | 3 term, respectively, in the | q → | -expanded form of the surface free energy f eff ( q → ) . Here, q → is the surface gradient relative to the (111) surface. The reason why the vicinal surface inclined in the <101> direction does not exhibit step-faceting is explained in terms of the one-dimensional spinless quasi-impenetrable attractive bosons at absolute zero.

  4. Faceting and roughening in quasicrystals

    NASA Technical Reports Server (NTRS)

    Garg, Anupam; Levine, Dov

    1987-01-01

    The question whether quasi-crystal shapes should be faceted is studied in a simple model of quasi-crystalline order. At T = 0, the model is proved to yield a completely faceted equilibrium shape in both two and three dimensions. At T greater than 0, an interface model is derived for a two-dimensional Penrose tiling. By mapping it onto a one-dimensional quasi-periodic Schroedinger equation, it is shown that the roughness exponent varies continuously with T at low T.

  5. Graphene-induced Ge (001) surface faceting

    NASA Astrophysics Data System (ADS)

    McElhinny, Kyle M.; Jacobberger, Robert M.; Zaug, Alexander J.; Arnold, Michael S.; Evans, Paul G.

    2016-05-01

    Faceted Ge surfaces result from the growth of a graphene overlayer on Ge (001) by chemical vapor deposition. The surface exhibits four-fold symmetry after faceting, with the surface normal of the facets tilted towards [100] from the average surface normal. X-ray reflectivity measurements allow the facet angles, directions, and symmetry to be measured precisely as a function of deposition conditions. Graphene grown from a CH4 precursor in a H2/Ar carrier atmosphere at temperatures from 870 to 920 °C yields facets on the Ge surface with an average facet angle of 7.70° ± 0.07°. Additionally, a distribution of facet angles is observed with an angular spread of approximately ± 1°. The facet pattern has four-fold symmetry over a large area with no indication of the formation of competing facets from reflectivity measurements. The facet angle tends toward the {107} facet of Ge with slight variation as a function of temperature indicating that the facet angles are dominated by surface energetics. The slight dependence on temperature is accompanied by a reconstruction of the surface into {001} facets under slow-cooling conditions, suggesting that the surface diffusion kinetics and temperature dependence have an important role in the formation of the faceted surface structure at lower temperatures.

  6. A Multi-Objective Advanced Design Methodology of Composite Beam-to-Column Joints Subjected to Seismic and Fire Loads

    SciTech Connect

    Pucinotti, Raffaele; Ferrario, Fabio; Bursi, Oreste S.

    2008-07-08

    A multi-objective advanced design methodology dealing with seismic actions followed by fire on steel-concrete composite full strength joints with concrete filled tubes is proposed in this paper. The specimens were designed in detail in order to exhibit a suitable fire behaviour after a severe earthquake. The major aspects of the cyclic behaviour of composite joints are presented and commented upon. The data obtained from monotonic and cyclic experimental tests have been used to calibrate a model of the joint in order to perform seismic simulations on several moment resisting frames. A hysteretic law was used to take into account the seismic degradation of the joints. Finally, fire tests were conducted with the objective to evaluate fire resistance of the connection already damaged by an earthquake. The experimental activity together with FE simulation demonstrated the adequacy of the advanced design methodology.

  7. Potential of Active-Steering Bogie for Reducing Lateral Axle Load Caused at Worn Welded Joints of Outer Rail in Curved Track

    NASA Astrophysics Data System (ADS)

    Iizuka, Tatsuya; Tanifuji, Katsuya; Soma, Hitoshi

    This paper deals with the potential of an active-steering bogie to reduce the large lateral axle load that arises at worn welded joints of the outer rail in a curved track when high-speed trains pass. The shape of the worn joint, called lateral ‘angular bent’, is modeled on the basis of the measured irregularity shape of actual joints. Then, numerical simulation of running on a curved track is carried out for a two-axle bogie vehicle to compare an active-steering bogie and a conventional nonsteering bogie. The behavior of the vehicle negotiating the curve is evaluated from the viewpoints of decreasing the peak value of lateral axle load within the allowance limit and maintaining the running stability. To satisfy the requirements, wheelset-supporting parameters and feedback gains for active-steering are optimized on a curved section of 400 m radius by the Genetic Algorithm. On the basis of the optimized wheelset-supporting parameter values, additional sets of feedback gains, which are adjusted for the curves of different radii, are proposed. The numerical simulation shows that the operation speed of a vehicle with active-steering bogies having the optimized parameter values has the potential to be raised to the possible speed for tilting trains while satisfying the criterion of riding comfort.

  8. Effects of normal and abnormal loading conditions on morphogenesis of the prenatal hip joint: application to hip dysplasia.

    PubMed

    Giorgi, Mario; Carriero, Alessandra; Shefelbine, Sandra J; Nowlan, Niamh C

    2015-09-18

    Joint morphogenesis is an important phase of prenatal joint development during which the opposing cartilaginous rudiments acquire their reciprocal and interlocking shapes. At an early stage of development, the prenatal hip joint is formed of a deep acetabular cavity that almost totally encloses the head. By the time of birth, the acetabulum has become shallower and the femoral head has lost substantial sphericity, reducing joint coverage and stability. In this study, we use a dynamic mechanobiological simulation to explore the effects of normal (symmetric), reduced and abnormal (asymmetric) prenatal movements on hip joint shape, to understand their importance for postnatal skeletal malformations such as developmental dysplasia of the hip (DDH). We successfully predict the physiological trends of decreasing sphericity and acetabular coverage of the femoral head during fetal development. We show that a full range of symmetric movements helps to maintain some of the acetabular depth and femoral head sphericity, while reduced or absent movements can lead to decreased sphericity and acetabular coverage of the femoral head. When an abnormal movement pattern was applied, a deformed joint shape was predicted, with an opened asymmetric acetabulum and the onset of a malformed femoral head. This study provides evidence for the importance of fetal movements in the prevention and manifestation of congenital musculoskeletal disorders such as DDH. PMID:26163754

  9. Effects of normal and abnormal loading conditions on morphogenesis of the prenatal hip joint: application to hip dysplasia

    PubMed Central

    Giorgi, Mario; Carriero, Alessandra; Shefelbine, Sandra J.; Nowlan, Niamh C.

    2015-01-01

    Joint morphogenesis is an important phase of prenatal joint development during which the opposing cartilaginous rudiments acquire their reciprocal and interlocking shapes. At an early stage of development, the prenatal hip joint is formed of a deep acetabular cavity that almost totally encloses the head. By the time of birth, the acetabulum has become shallower and the femoral head has lost substantial sphericity, reducing joint coverage and stability. In this study, we use a dynamic mechanobiological simulation to explore the effects of normal (symmetric), reduced and abnormal (asymmetric) prenatal movements on hip joint shape, to understand their importance for postnatal skeletal malformations such as developmental dysplasia of the hip (DDH). We successfully predict the physiological trends of decreasing sphericity and acetabular coverage of the femoral head during fetal development. We show that a full range of symmetric movements helps to maintain some of the acetabular depth and femoral head sphericity, while reduced or absent movements can lead to decreased sphericity and acetabular coverage of the femoral head. When an abnormal movement pattern was applied, a deformed joint shape was predicted, with an opened asymmetric acetabulum and the onset of a malformed femoral head. This study provides evidence for the importance of fetal movements in the prevention and manifestation of congenital musculoskeletal disorders such as DDH. PMID:26163754

  10. Joint longitudinal hurdle and time-to-event models: an application related to viral load and duration of the first treatment regimen in patients with HIV initiating therapy.

    PubMed

    Brilleman, Samuel L; Crowther, Michael J; May, Margaret T; Gompels, Mark; Abrams, Keith R

    2016-09-10

    Shared parameter joint models provide a framework under which a longitudinal response and a time to event can be modelled simultaneously. A common assumption in shared parameter joint models has been to assume that the longitudinal response is normally distributed. In this paper, we instead propose a joint model that incorporates a two-part 'hurdle' model for the longitudinal response, motivated in part by longitudinal response data that is subject to a detection limit. The first part of the hurdle model estimates the probability that the longitudinal response is observed above the detection limit, whilst the second part of the hurdle model estimates the mean of the response conditional on having exceeded the detection limit. The time-to-event outcome is modelled using a parametric proportional hazards model, assuming a Weibull baseline hazard. We propose a novel association structure whereby the current hazard of the event is assumed to be associated with the current combined (expected) outcome from the two parts of the hurdle model. We estimate our joint model under a Bayesian framework and provide code for fitting the model using the Bayesian software Stan. We use our model to estimate the association between HIV RNA viral load, which is subject to a lower detection limit, and the hazard of stopping or modifying treatment in patients with HIV initiating antiretroviral therapy. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27027882

  11. Characterization and evaluation of triamcinolone, raloxifene, and their dual-loaded microspheres as prospective local treatment system in rheumatic rat joints.

    PubMed

    Ocal, Yigit; Kurum, Baris; Karahan, Siyami; Tezcaner, Aysen; Ozen, Seza; Keskin, Dilek

    2014-08-01

    In this study, injectable microspheres were developed for the local treatment of joint degeneration in rheumatoid arthritis (RA). Microspheres loaded with triamcinolone (TA), a corticosteroid drug, and/or raloxifene (Ral), a cartilage regenerative drug, were prepared with a biodegradable and biocompatible polymer, polycaprolactone (PCL). Microspheres were optimized for particle size, structural properties, drug release, and loading properties. In vitro release of Ral was very slow because of the low solubility of the drug and hydrophobic nature of PCL. However, when coloaded with TA, both drugs were released at higher amounts compared with their single forms. Smallest particle sizes were obtained in dual drug-loaded microspheres. In vitro cytotoxicity tests showed biocompatibility of microspheres. In vivo bioefficacy of these microspheres was also examined in adjuvant-induced arthritis model in rats. In vivo histological studies of control groups showed development of RA with high median lesion score (5.0). Compared with control and intra-articular free drug injections, microsphere treatment groups showed lower lesion scores and better healing outcomes in histological evaluations. Results suggest that a controlled delivery system of TA and RAL by a single injection in inflamed joints holds promise for healing and suppressing inflammation. PMID:24939720

  12. Dynamic strain distribution measurement and crack detection of an adhesive-bonded single-lap joint under cyclic loading using embedded FBG

    NASA Astrophysics Data System (ADS)

    Ning, Xiaoguang; Murayama, Hideaki; Kageyama, Kazuro; Wada, Daichi; Kanai, Makoto; Ohsawa, Isamu; Igawa, Hirotaka

    2014-10-01

    In this study, the dynamic strain distribution measurement of an adhesive-bonded single-lap joint was carried out in a cyclic load test using a fiber Bragg grating (FBG) sensor embedded into the adhesive/adherend interface along the overlap length direction. Unidirectional carbon fiber reinforced plastic (CFRP) substrates were bonded by epoxy resin to form the joint, and the FBG sensor was embedded into the surface of one substrate during its curing. The measurement was carried out with a sampling rate of 5 Hz by the sensing system, based on the optical frequency domain reflectometry (OFDR) throughout the test. A finite element analysis (FEA) was performed for the measurement evaluation using a three-dimensional model, which included the embedded FBG sensor. The crack detection method, based on the longitudinal strain distribution measurement, was introduced and performed to estimate the cracks that occurred at the adhesive/adherend interface in the test.

  13. The effects of neuromuscular exercise on medial knee joint load post-arthroscopic partial medial meniscectomy: ‘SCOPEX’ a randomised control trial protocol

    PubMed Central

    2012-01-01

    Background Meniscectomy is a risk factor for knee osteoarthritis, with increased medial joint loading a likely contributor to the development and progression of knee osteoarthritis in this group. Therefore, post-surgical rehabilitation or interventions that reduce medial knee joint loading have the potential to reduce the risk of developing or progressing osteoarthritis. The primary purpose of this randomised, assessor-blind controlled trial is to determine the effects of a home-based, physiotherapist-supervised neuromuscular exercise program on medial knee joint load during functional tasks in people who have recently undergone a partial medial meniscectomy. Methods/design 62 people aged 30–50 years who have undergone an arthroscopic partial medial meniscectomy within the previous 3 to 12 months will be recruited and randomly assigned to a neuromuscular exercise or control group using concealed allocation. The neuromuscular exercise group will attend 8 supervised exercise sessions with a physiotherapist and will perform 6 exercises at home, at least 3 times per week for 12 weeks. The control group will not receive the neuromuscular training program. Blinded assessment will be performed at baseline and immediately following the 12-week intervention. The primary outcomes are change in the peak external knee adduction moment measured by 3-dimensional analysis during normal paced walking and one-leg rise. Secondary outcomes include the change in peak external knee adduction moment during fast pace walking and one-leg hop and change in the knee adduction moment impulse during walking, one-leg rise and one-leg hop, knee and hip muscle strength, electromyographic muscle activation patterns, objective measures of physical function, as well as self-reported measures of physical function and symptoms and additional biomechanical parameters. Discussion The findings from this trial will provide evidence regarding the effect of a home-based, physiotherapist

  14. Design of a lattice-based faceted classification system

    NASA Technical Reports Server (NTRS)

    Eichmann, David A.; Atkins, John

    1992-01-01

    We describe a software reuse architecture supporting component retrieval by facet classes. The facets are organized into a lattice of facet sets and facet n-tuples. The query mechanism supports precise retrieval and flexible browsing.

  15. Lumbar facet injection for the treatment of chronic piriformis myofascial pain syndrome: 52 case studies

    PubMed Central

    Huang, Jen-Ting; Chen, Han-Yu; Hong, Chang-Zern; Lin, Ming-Ta; Chou, Li-Wei; Chen, Hsin-Shui; Tsai, Chien-Tsung; Chang, Wen-Dien

    2014-01-01

    Background and aims The aim of this study was to demonstrate the effectiveness of lumbar facet joint injection for piriformis myofascial pain syndrome. Methods Fifty-two patients with chronic myofascial pain in the piriformis muscle each received a lumbar facet injection into the ipsilateral L5–S1 facet joint region, using the multiple insertion technique. Subjective pain intensity, trunk extension range, and lumbar facet signs were measured before, immediately after, and 2 weeks after injection. Thirty-six patients received follow-up for 6 months. Results Immediately after the injection, 27 patients (51.9%) had complete pain subsidence, 19 patients (36.5%) had pain reduction to a tolerable level, and only 6 patients (11.5%) had no pain relief to a tolerable level. Mean pain intensity was reduced from 7.4±0.9 to 1.6±2.1 after injection (P<0.01). This effectiveness lasted for 2 weeks in 49 patients (94.2%), and lasted for approximately 6 months in 35 (97.2%) of 36 patients. The mean range of motion increased from 13.4±6.8 degrees to 22.1±6.0 degrees immediately after injection, and further increased 2 weeks and 6 months later. Immediately after injection, 45 patients (86.5%) had no facet sign. In addition, 90.4% and 94.4% of patients had no facet sign after 2 weeks and after 6 months, respectively. Conclusions It is important to identify the possible cause of piriformis myofascial pain syndrome. If this pain is related to lumbar facet lesions, lumbar facet joint injection can immediately suppress piriformis myofascial pain symptoms. This effectiveness may last for at least 6 months in most patients. This study further supports the importance of eliminating the underlying etiological lesion for complete and effective relief of myofascial pain syndrome. PMID:25170256

  16. Quantification of Subtalar Posterior Facet Involvement During Intramedullary Guidance of Total Ankle Arthroplasty:A Cadaveric Study.

    PubMed

    DeMill, Shyler L; McAlister, Jeffrey E; Hyer, Christopher F; Berlet, Gregory C

    2015-01-01

    Total ankle arthroplasty is an evolving treatment of ankle arthritis. One implant uses intramedullary guidance to enhance accuracy by accessing the tibial canal through the inferior aspect of the foot, potentially placing the subtalar joint articulation at risk. The purpose of the present cadaveric anatomic evaluation was to identify posterior subtalar articular facet joint involvement during intramedullary guidance to the tibial canal. Ten below-the-knee cadaveric specimens were used. After drilling into the tibial medullary canal with a 6-mm drill bit and using the standard targeting jig, the specimens were dissected, and the posterior facet was evaluated. We graded posterior facet involvement according to the location of the drill hole and, if within the facet, the percentage of the facet violated by the drill bit, with 100% representing the full circumference of the 6-mm drill bit. Of the 8 specimens in which the drill bit passed through the subtalar posterior articular facet, the encroachment was peripheral in all cases, with no specimen showing circumferential 6-mm drill bit articular penetration (no cases with 100%). Sinus tarsi penetration occurred in 20% of the cases. The dissections with articular involvement included 3 specimens with >50% of the drill bit penetrating and 5 with <50%. The portion of the posterior facet involved among the specimens that were violated was anterocentral in the joint. A risk of damage to the posterior facet of the subtalar joint exists with intramedullary total ankle systems. Our study has demonstrated that the drill bit will involve the anterocentral and anterolateral portions of the posterior facet of the subtalar joint, with <6 mm articular disruption in all cases. PMID:26015304

  17. How do metacarpophalangeal joint extension, collateromotion and axial rotation influence dorsal surface strains of the equine proximal phalanx at different loads in vitro?

    PubMed

    Singer, Ellen; Garcia, Tanya; Stover, Susan

    2013-02-22

    The biomechanical circumstances that promote sagittal fracture of the equine proximal phalanx (P1) are poorly understood. In order to improve our understanding of equine metacarpophalangeal joint (MCPJ) biomechanics and potential aetiologies of sagittal P1 fractures, the study objectives were to quantify P1 bone strains, collateromotion and axial rotation during MCPJ extension under controlled loading circumstances. Unilateral limbs from six cadavers were instrumented with bone reference markers for measurement of P1 movement relative to third metacarpal bone positions during axial limb loading to 10,500N. Bone reference markers recorded by video were digitized and the movement analyzed during MCPJ extension. Concurrently, dorsoproximal P1 surface strains were measured with one uniaxial and one rosette strain gauge. Strain gauge data was reduced to determine principal and shear strain magnitude and direction. External axial rotation and collateromotion increased with increasing MCPJ extension. Maximum principal strain increased linearly as load increased from 2000 to 10,500N. Minimum principal and maximum shear strains had curvilinear relationships with limb loading, with negligible strain magnitude until approximately 6000N load, after which strain increased rapidly. The direction of P1 minimum principal strain shifted approximately 30-40° as load increased from 5400N to 10,000N, moving from proximolateral-distomedial to a nearly proximodistal direction. At near maximal MCPJ extension, with concurrent axial rotation and collateromotion, a rapid increase in dorsoproximal P1 bone strain and a change in principal strain direction occurred. The alterations in principal strain magnitude and direction associated with maximal MCPJ extension may support a biomechanical theory for sagittal P1 fracture occurrence in horses. PMID:23246042

  18. Effects of neuromuscular fatigue on perceptual-cognitive skills between genders in the contribution to the knee joint loading during side-stepping tasks.

    PubMed

    Khalid, Abdul Jabbar; Harris, Sujae Ian; Michael, Loke; Joseph, Hamill; Qu, Xingda

    2015-01-01

    This study investigated whether neuromuscular fatigue affects the neuromuscular control of an athlete within a sports context setting and whether these effects were more pronounced in the females. Lower limb joint kinetics of 6 male and 6 female inter-varsity soccer players performing side-stepping tasks in non-fatigue versus fatigue and anticipated versus unanticipated conditions were quantified using 10 Motion Analysis Corporation cameras and a Kistler(™) force platform. The Yo-Yo intermittent recovery Level 1 fatigue protocol was employed. Stance foot initial contact and peak forces, and peak joint knee moments of the lower limb were submitted to a 3-way mixed-model repeated measure ANOVA. The results suggested that males tend to elicit significantly higher knee joint loadings when fatigued. In addition, males elicited significantly higher peak proximal tibia anterior/posterior shear force, vertical ground reaction force at initial contact and peak internal rotational moments than females. These findings suggested that males were at greater overall injury risk than females, especially in the sagittal plane. Neuromuscular control-based training programmes/interventions that are designed to reduce the risk of the non-contact ACL injury need to be customised for the different genders. PMID:25562469

  19. Molecular simulation of the influence of interface faceting on the shock sensitivity of a model plastic bonded explosive.

    PubMed

    Shi, Yunfeng; Brenner, Donald W

    2008-11-27

    Molecular dynamics simulations are used to model the shock loading of an interface with various degrees of nanometer scale faceting between an inert binder and an energetic crystal. The facets create regions of local compression that induce exothermic reaction that leads to local hotspots and an increased shock sensitivity to detonation. Two mechanisms for compression and hotspot formation are identified that depend on the shock impedance mismatch between the binder and energetic crystal, namely shock focusing and local compression of the facets. These results provide a possible explanation for why spherical RDX crystals in cast polymer-bonded explosives appear less shock sensitive than RDX with more faceted morphologies. PMID:18973371

  20. Abutment screw loosening of endosseous dental implant body/abutment joint by cyclic torsional loading test at the initial stage.

    PubMed

    Katsuta, Yasuhiro; Watanabe, Fumihiko

    2015-01-01

    Cyclic torsional loading tests were carried out in the laboratory using various implant systems, in order to clarify differences between the systems in loosening of abutment screws. Six samples from six commercially available abutment systems were used, giving a total of 36 samples. Four of the systems used internal connections, and two used external connections. The abutment screw for each system was tightened to a torque value specified by the manufacturer, and after 5 min, the loosening torque was measured using a digital torque meter. Measurements were taken twice, and a second measurement was taken as a reference value. A cyclic torsional loading test with 100,000 cycles was performed on the sample, and the loosening torque was again measured after the test. In conclusion, loosening of the abutment screw occurred as a result of cyclic torsional loading, and the degree of loosening varied with each implant system. PMID:26632240

  1. Ex vivo determination of bone tissue strains for an in vivo mouse tibial loading model.

    PubMed

    Carriero, Alessandra; Abela, Lisa; Pitsillides, Andrew A; Shefelbine, Sandra J

    2014-07-18

    Previous studies introduced the digital image correlation (DIC) as a viable technique for measuring bone strain during loading. In this study, we investigated the sensitivity of a DIC system in determining surface strains in a mouse tibia while loaded in compression through the knee joint. Specifically, we examined the effect of speckle distribution, facet size and overlap, initial vertical alignment of the bone into the loading cups, rotation with respect to cameras, and ex vivo loading configurations on the strain contour maps measured with a DIC system. We loaded tibiae of C57BL/6 mice (12 and 18 weeks old male) up to 12 N at 8 N/min. Images of speckles on the bone surface were recorded at 1N intervals and DIC was used to compute strains. Results showed that speckles must have the correct size and density with respect to the facet size of choice for the strain distribution to be computed and reproducible. Initial alignment of the bone within the loading cups does not influence the strain distribution measured during peak loading, but bones must be placed in front of the camera with the same orientation in order for strains to be comparable. Finally, the ex vivo loading configurations with the tibia attached to the entire mouse, or to the femur and foot, or only to the foot, showed different strain contour maps. This work provides a better understanding of parameters affecting full field strain measurements from DIC in ex vivo murine tibial loading tests. PMID:24835472

  2. A comparison of slow, uphill and fast, level walking on lower extremity biomechanics and tibiofemoral joint loading in obese and nonobese adults.

    PubMed

    Haight, Derek J; Lerner, Zachary F; Board, Wayne J; Browning, Raymond C

    2014-02-01

    We determined if slow, uphill walking (0.75 m/s, 6°) reduced tibiofemoral (TF) loading compared to faster, level walking (1.50 m/s) in obese and nonobese adults. We collected kinematic, kinetic, and electromyographic data as 9 moderately obese and 10 nonobese participants walked on a dual-belt instrumented treadmill. We used OpenSim to scale a musculoskeletal model and calculate joint kinematics, kinetics, muscle forces, and TF forces. Compressive TF forces were greater in the obese adults during both speed/grade combinations. During level walking, obese participants walked with a straighter leg than nonobese participants, resulting in early stance vasti muscle forces that were similar in the obese and nonobese participants. Early stance peak compressive TF forces were reduced by 23% in obese (2,352 to 1,811 N) and 35% in nonobese (1,994 to 1,303 N) individuals during slow, uphill walking compared to brisk level walking. Late stance peak TF forces were similar across speeds/grades, but were greater in obese (∼2,900 N) compared to nonobese (∼1,700 N) individuals. Smaller early stance TF loads and loading rates suggest that slow, uphill walking may be appropriate exercise for obese individuals at risk for musculoskeletal pathology or pain. PMID:24127395

  3. Crystallographic Facet-Induced Toxicological Responses by Faceted Titanium Dioxide Nanocrystals.

    PubMed

    Liu, Ning; Li, Kai; Li, Xi; Chang, Yun; Feng, Yanlin; Sun, Xiujuan; Cheng, Yan; Wu, Zhijian; Zhang, Haiyuan

    2016-06-28

    Toxicological responses of nanomaterials have been closely correlated to their physicochemical properties, and establishment of a property-activity relationship of nanomaterials is favorable for a deep understanding of the nanomaterials' toxicity mechanism, prospectively predicting nanomaterials' potential hazards and rationally designing safer nanomaterials. Faceted nanomaterials usually exhibit more versatile and effective performance than spherical nanomaterials due to their selectively exposed crystallographic facets with high densities of unsaturated atoms. These facets have high surface reactivity, capable of eliciting strong interactions with biological systems. Few studies paid attention to the toxic behaviors of faceted nanomaterials in terms of their distinctive facets. In the present study, the toxicological role of the crystallographic facets of TiO2 nanomaterials was investigated, and the precise property-activity relationship was exploited to clearly understand the toxicity of faceted nanomaterials. A series of faceted TiO2 nanocrystals with the morphology of truncated octahedral bipyramids were prepared to expose different percentages of {101} and {001} facets on the surface. Density functional theory calculation revealed that {101} facets could only molecularly absorb water molecules while {001} facets due to their surface-unsaturated Ti atoms could dissociate the absorbed water molecules to generate hydroxyl radicals. Biophysical assessments corroborated the increased production of hydroxyl radicals on the {001} facets compared to {101} facets, which endowed {001} facets with strong hemolytic activity and elicited severe toxicities. A series of increased oxidative stress toxicological responses, including cellular ROS production, heme oxygenase-1 expression, cellular GSH depletion, and mitochondrial dysfunctions, were triggered by faceted TiO2 nanocrystals with progressively increased {001} percentages, demonstrating the toxicological roles of {001

  4. A thermomechanical anisotropic model for shock loading of elastic-plastic and elastic-viscoplastic materials with application to jointed rock

    NASA Astrophysics Data System (ADS)

    Rubin, M. B.; Vorobiev, O.; Vitali, E.

    2016-07-01

    A large deformation thermomechanical model is developed for shock loading of a material that can exhibit elastic and inelastic anisotropy. Use is made of evolution equations for a triad of microstructural vectors mathbf{m}i (hbox {i}=1,2,3) which model elastic deformations and directions of anisotropy. Specific constitutive equations are presented for a material with orthotropic elastic response. The rate of inelasticity depends on an orthotropic yield function that can be used to model weak fault planes with failure in shear and which exhibits a smooth transition to isotropic response at high compression. Moreover, a robust, strongly objective numerical algorithm is proposed for both rate-independent and rate-dependent response. The predictions of the continuum model are examined by comparison with exact steady-state solutions. Also, the constitutive equations are used to obtain a simplified continuum model of jointed rock which is compared with high fidelity numerical solutions that model a persistent system of joints explicitly in the rock medium.

  5. Optical Fiber Distributed Sensing Structural Health Monitoring (SHM) Strain Measurements Taken During Cryotank Y-Joint Test Article Load Cycling at Liquid Helium Temperatures

    NASA Technical Reports Server (NTRS)

    Allison, Sidney G.; Prosser, William H.; Hare, David A.; Moore, Thomas C.; Kenner, Winfred S.

    2007-01-01

    This paper outlines cryogenic Y-joint testing at Langley Research Center (LaRC) to validate the performance of optical fiber Bragg grating strain sensors for measuring strain at liquid helium temperature (-240 C). This testing also verified survivability of fiber sensors after experiencing 10 thermal cool-down, warm-up cycles and 400 limit load cycles. Graphite composite skins bonded to a honeycomb substrate in a sandwich configuration comprised the Y-joint specimens. To enable SHM of composite cryotanks for consideration to future spacecraft, a light-weight, durable monitoring technology is needed. The fiber optic distributed Bragg grating strain sensing system developed at LaRC is a viable substitute for conventional strain gauges which are not practical for SHM. This distributed sensing technology uses an Optical Frequency Domain Reflectometer (OFDR). This measurement approach has the advantage that it can measure hundreds of Bragg grating sensors per fiber and the sensors are all written at one frequency, greatly simplifying fiber manufacturing. Fiber optic strain measurements compared well to conventional strain gauge measurements obtained during these tests. These results demonstrated a high potential for a successful implementation of a SHM system incorporating LaRC's fiber optic sensing system on the composite cryotank and other future cryogenic applications.

  6. Optical fiber distributed sensing structural health monitoring (SHM) strain measurements taken during cryotank Y-joint test article load cycling at liquid helium temperatures

    NASA Astrophysics Data System (ADS)

    Allison, Sidney G.; Prosser, William H.; Hare, David A.; Moore, Thomas C.; Kenner, W. S.

    2007-09-01

    This paper outlines cryogenic Y-joint testing at Langley Research Center (LaRC) to validate the performance of optical fiber Bragg grating strain sensors for measuring strain at liquid helium temperature (-240°C). This testing also verified survivability of fiber sensors after experiencing 10 thermal cool-down, warm-up cycles and 400 limit load cycles. Graphite composite skins bonded to a honeycomb substrate in a sandwich configuration comprised the Y-joint specimens. To enable SHM of composite cryotanks for consideration to future spacecraft, a light-weight, durable monitoring technology is needed. The fiber optic distributed Bragg grating strain sensing system developed at LaRC is a viable substitute for conventional strain gauges which are not practical for SHM. This distributed sensing technology uses an Optical Frequency Domain Reflectometer (OFDR). This measurement approach has the advantage that it can measure hundreds of Bragg grating sensors per fiber and the sensors are all written at one frequency, greatly simplifying fiber manufacturing. Fiber optic strain measurements compared well to conventional strain gauge measurements obtained during these tests. These results demonstrated a high potential for a successful implementation of a SHM system incorporating LaRC's fiber optic sensing system on the composite cryotank and other future cryogenic applications.

  7. Faceting of Re (1121) induced by oxygen

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Chen, Wenhua; Madey, Theodore E.

    2006-03-01

    The oxygen-induced nanoscale faceting of Re (1121) has been studied by low energy electron diffraction (LEED) and Auger electron spectroscopy (AES); the results are compared with recent STM and LEED studies of O-induced faceting of Re(1231). The evolution of surface morphology depends on oxygen exposures and deposition temperatures. Re(1121) remains planar after oxygen deposition at 300K. Annealing O-covered Re(1121) between 800K-1200K leads to the formation of (0110) and (1010) facets that coexist with the (1121) surface. Under oxidation conditions, i.e. dosing a large amount of oxygen at high temperatures (900-1000K), the (1121) surface is completely covered by 4-sided nanoscale pyramidal structures whose facets are identified as (0110), (1010), (0111) and (1011). The fact that the (1121) surface becomes completely faceted only after oxidation is consistent with our previous data for O-induced faceting of Re(1231), where one facet has the (1121) orientation and is unstable against oxidation. The faceted O/Re surfaces may be potential templates to grow nano-structures with narrow size distribution, and may also be substrates to study structural sensitivity in catalytic reactions.

  8. Eight Key Facets of Small Business Management.

    ERIC Educational Resources Information Center

    Scott, James Calvert

    1980-01-01

    Identifies eight key facets of small business management and suggests activities that may be used to assist in their development. The key facets are (1) product or service, (2) competition, (3) marketing strategies, (4) personnel needs, (5) equipment and facility needs, (6) finances, (7) planning, and (8) entrepreneurship. (JOW)

  9. Facets of the balanced minimal evolution polytope.

    PubMed

    Forcey, Stefan; Keefe, Logan; Sands, William

    2016-08-01

    The balanced minimal evolution (BME) method of creating phylogenetic trees can be formulated as a linear programming problem, minimizing an inner product over the vertices of the BME polytope. In this paper we undertake the project of describing the facets of this polytope. We classify and identify the combinatorial structure and geometry (facet inequalities) of all the facets in dimensions up to five, and classify even more facets in all dimensions. A full set of facet inequalities would allow a full implementation of the simplex method for finding the BME tree-although there are reasons to think this an unreachable goal. However, our results provide the crucial first steps for a more likely-to-be-successful program: finding efficient relaxations of the BME polytope. PMID:26714816

  10. Crack Front Segmentation and Facet Coarsening in Mixed-Mode Fracture.

    PubMed

    Chen, Chih-Hung; Cambonie, Tristan; Lazarus, Veronique; Nicoli, Matteo; Pons, Antonio J; Karma, Alain

    2015-12-31

    A planar crack generically segments into an array of "daughter cracks" shaped as tilted facets when loaded with both a tensile stress normal to the crack plane (mode I) and a shear stress parallel to the crack front (mode III). We investigate facet propagation and coarsening using in situ microscopy observations of fracture surfaces at different stages of quasistatic mixed-mode crack propagation and phase-field simulations. The results demonstrate that the bifurcation from propagating a planar to segmented crack front is strongly subcritical, reconciling previous theoretical predictions of linear stability analysis with experimental observations. They further show that facet coarsening is a self-similar process driven by a spatial period-doubling instability of facet arrays. PMID:26765005

  11. Crack Front Segmentation and Facet Coarsening in Mixed-Mode Fracture

    NASA Astrophysics Data System (ADS)

    Chen, Chih-Hung; Cambonie, Tristan; Lazarus, Veronique; Nicoli, Matteo; Pons, Antonio J.; Karma, Alain

    2015-12-01

    A planar crack generically segments into an array of "daughter cracks" shaped as tilted facets when loaded with both a tensile stress normal to the crack plane (mode I) and a shear stress parallel to the crack front (mode III). We investigate facet propagation and coarsening using in situ microscopy observations of fracture surfaces at different stages of quasistatic mixed-mode crack propagation and phase-field simulations. The results demonstrate that the bifurcation from propagating a planar to segmented crack front is strongly subcritical, reconciling previous theoretical predictions of linear stability analysis with experimental observations. They further show that facet coarsening is a self-similar process driven by a spatial period-doubling instability of facet arrays.

  12. Effect of aqueous solution and load on the formation of DLC transfer layer against Co-Cr-Mo for joint prosthesis.

    PubMed

    Guo, Feifei; Zhou, Zhifeng; Hua, Meng; Dong, Guangneng

    2015-09-01

    Diamond-like carbon (DLC) coating exhibits excellent mechanical properties such as high hardness, low friction and wear, which offer a promising solution for the metal-on-metal hip joint implants. In the study, the hydrogen-free DLC coating with the element Cr as the interlay addition was deposited on the surface of the Co-Cr-Mo alloy by a unbalanced magnetron sputtering method. The coating thickness was controlled as 2 µm. Nano-indentation test indicated the hardness was about 13 GPa. DLC coated Co-Cr-Mo alloy disc against un-coated Co-Cr-Mo alloy pin (spherical end SR9.5) comprised the friction pairs in the pin-on-disc tribotest under bovine serum albumin solution (BSA) and physiological saline(PS).The tribological behavior under different BSA concetrations(2-20 mg/ml), and applied load (2-15N) was investigated.DLC transfer layer did not form under BSA solution, even though different BSA concetration and applied load changed. The coefficient of friction(COF) under 6 mg/ml BSA at 10 N was the lowest as 0.10. A higher COF of 0.13 was obtained under 20 mg/ml BSA. The boundary absorption layer of protein is the main factor for the counterparts. However, the continous DLC transfer layer was observed under PS solution, which make a lower COF of 0.08. PMID:25967039

  13. Experimental and analytical program to determine strains in 737 LAP splice joints subjected to normal fuselage pressurization loads

    SciTech Connect

    Roach, D.P.; Jeong, D.Y.

    1996-02-01

    The Federal Aviation Administration Technical Center (FAATC) has initiated several research projects to assess the structural integrity of the aging commercial aircraft fleet. One area of research involves the understanding of a phenomenon known as ``Widespread Fatigue Damage`` or WFD, which refers to a type of multiple element cracking that degrades the damage tolerance capability of an aircraft structure. Research on WFD has been performed both experimentally and analytically including finite element modeling of fuselage lap splice joints by the Volpe Center. Fuselage pressurization tests have also been conducted at the FAA`s Airworthiness Assurance NDI Validation Center (AANC) to obtain strain gage data from select locations on the FAA/AANC 737 Transport Aircraft Test Bed. One-hundred strain channels were used to monitor five different lap splice bays including the fuselage skin and substructure elements. These test results have been used to evaluate the accuracy of the analytical models and to support general aircraft analysis efforts. This paper documents the strain fields measured during the AANC tests and successfully correlates the results with analytical predictions.

  14. Modeling of fracture and durability of paste-bonded composite joints subjected to hygro-thermal-mechanical loading

    NASA Astrophysics Data System (ADS)

    Harris, David Lee

    The objective of the research is to characterize the behavior of composite/composite joints with paste adhesive using both experimental testing and analytical modeling. In comparison with the conventional tape adhesive, joining composites using paste adhesive provides several advantages. The carbon fiber laminate material systems employed in this study included IM7 carbon fibers and 977-3 epoxy matrix assembled in prepreg tape, and AS4 carbon fibers and 977-3 epoxy matrix as a five-harness satin weave. The adhesive employed was EA 9394 epoxy. All laminates and test specimens were fabricated and inspected by Boeing using their standard propriety procedures. Three types of test specimens were used in the program. They were bonded double-lap shear (DLS), bonded double cantilever beam (DCB) and bonded interlaminar tension (ILT) specimens. A group of specimens were conditioned at elevated temperature and humidity in an environmental chamber at Boeing's facility and their moisture absorption recorded with time. Specimens were tested at room temperature dry and elevated temperatures. DCB and DLS specimens were tested in fatigue as well as static conditions. Two-dimensional finite element models of the three configurations were developed for determining stresses and strains using the ABAQUS finite element package code. Due to symmetry, only the one-half of the specimen needed to be considered thus reducing computational time. The effect of the test fixture is not taken into account instead equivalent distributed stresses are applied directly on the composite laminates. For each of the specimen, the distribution of Mises stress and the first strain invariant J1 are obtained to identify potential failure locations within a specimen.

  15. [Effects of intervertebral disc degeneration on biomechanics behavior characteristics of L4-L5 under the vertical load].

    PubMed

    Hu, Yingchun; Ou, Yalong; Hu, Yizhi; Yu, Binghao

    2015-02-01

    A geometrical model of L4-L5 lumbar segment was constructed using a three-dimensional graphics software. Four conditions of the degenerated discs, i. e. light degeneration, moderate degeneration, severe degeneration and complete excision degeneration, were simulated with loading situations using finite element method under the condition of appropriate computational accuracy. By applying a vertical load of 378.93 N on L4 vertebral plate, stress nephograms on joint isthmus under four different working conditions were obtained. The results showed that the contacted area of facet joint was influenced by the degree of intervertebral disc degeneration level, which influenced the mises stress on joint isthmus. It was proved that joint isthmus was the important pressure-proof structure of the back of lumbar vertebra, and the stress values and distribution were related to structural stiffness of the back of lumbar vertebra as well as the contact area of facet joint. The conclusion could be the theoretical reference for the analysis of spinal biomechanics and artificial disc replacement as well. PMID:25997266

  16. Framework Application for Core Edge Transport Simulation (FACETS)

    SciTech Connect

    Krasheninnikov, Sergei; Pigarov, Alexander

    2011-10-15

    The FACETS (Framework Application for Core-Edge Transport Simulations) project of Scientific Discovery through Advanced Computing (SciDAC) Program was aimed at providing a high-fidelity whole-tokamak modeling for the U.S. magnetic fusion energy program and ITER through coupling separate components for each of the core region, edge region, and wall, with realistic plasma particles and power sources and turbulent transport simulation. The project also aimed at developing advanced numerical algorithms, efficient implicit coupling methods, and software tools utilizing the leadership class computing facilities under Advanced Scientific Computing Research (ASCR). The FACETS project was conducted by a multi-discipline, multi-institutional teams, the Lead PI was J.R. Cary (Tech-X Corp.). In the FACETS project, the Applied Plasma Theory Group at the MAE Department of UCSD developed the Wall and Plasma-Surface Interaction (WALLPSI) module, performed its validation against experimental data, and integrated it into the developed framework. WALLPSI is a one-dimensional, coarse grained, reaction/advection/diffusion code applied to each material boundary cell in the common modeling domain for a tokamak. It incorporates an advanced model for plasma particle transport and retention in the solid matter of plasma facing components, simulation of plasma heat power load handling, calculation of erosion/deposition, and simulation of synergistic effects in strong plasma-wall coupling.

  17. Skeletal development of hallucal tarsometatarsal joint curvature and angulation in extant apes and modern humans.

    PubMed

    Gill, Corey M; Bredella, Miriam A; DeSilva, Jeremy M

    2015-11-01

    The medial cuneiform, namely the curvature and angulation of its distal facet with metatarsal 1, is crucial as a stabilizer in bipedal locomotion and an axis upon which the great toe medially deviates during arboreal locomotion in extant apes. Previous work has shown that facet curvature and angulation in adult dry-bone specimens can distinguish African apes from Homo, and can even distinguish among species of Gorilla. This study provides the first ontogenetic assessment of medial cuneiform curvature and angulation in juvenile (n = 68) and adult specimens (n = 102) using computed tomography in humans and extant ape specimens, including Pongo. Our data find that modern human juveniles initially have a convex and slightly medially oriented osseous surface of the developing medial cuneiform distal facet that flattens and becomes more distally oriented with age. The same pattern (though of a different magnitude) occurs developmentally in the chimpanzee medial cuneiform, but not in Gorilla or Pongo, whose medial cuneiform facet angulation remains unchanged ontogenetically. These data suggest that the medial cuneiform ossifies in a distinguishable pattern between Pongo, Gorilla, Pan, and Homo, which may in part be due to subtle differences in the loading environment at the hallucal tarsometatarsal joint-a finding that has important implications for interpreting fossil medial cuneiforms. PMID:26319411

  18. Faceting of Re (1121) induced by ammonia

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Chen, Wenhua; Madey, Theodore E.; Jacob, Timo

    2007-03-01

    The ammonia-induced nanoscale faceting of Re (1121) has been studied by LEED and STM; the results are compared with recent studies of O-induced faceting of Re(1121). After exposure to ammonia at 700K, the Re(1121) surface only shows a (1x2) reconstruction and remains planar (ammonia dissociates on Re, and only N remains on the surface at T>700K). By exposure to ammonia at 900K, Re(1121) becomes completely faceted, forming 2-sided ridge-like structures with (1342) and (3142) facets. However, this morphology is different from that in O-induced faceting of Re(1121). The two ridge sides, (1342) and (3142), are vicinal surfaces of closed-packed (0110) and (1010) respectively; these latter two surfaces appear as facets in O-induced faceting of Re(1121). DFT calculations are implemented to understand the origin of the different morphologies. Our work demonstrates that it is possible to tailor the surface morphology by choosing appropriate adsorbate and annealing conditions, which in turn provides model systems to study structural sensitivity in catalytic reactions as well as potential templates to grow nanostructures.

  19. Method for partially coating laser diode facets

    NASA Technical Reports Server (NTRS)

    Dholakia, Anil R. (Inventor)

    1990-01-01

    Bars of integral laser diode devices cleaved from a wafer are placed with their p regions abutting and n regions abutting. A thin BeCu mask having alternate openings and strips of the same width as the end facets is used to mask the n region interfaces so that multiple bars can be partially coated over their exposed p regions with a reflective or partial reflective coating. The partial coating permits identification of the emitting facet from the fully coated back facet during a later device mounting procedure.

  20. Peripartum changes of the sacroiliac joints on MRI: increasing mechanical load correlating with signs of edema and inflammation kindling spondyloarthropathy in the genetically prone.

    PubMed

    Eshed, Iris; Miloh-Raz, Hadar; Dulitzki, Mordechai; Lidar, Zvi; Aharoni, Dvora; Liberman, Boaz; Lidar, Merav

    2015-08-01

    The purpose of this study is to characterize the MRI changes of the sacroiliac joints (SIJs) during pregnancy and following labor and to correlate them with clinical symptoms. Ninety-three pelvic and hip MRIs of pregnant and ≤6 months postpartum women were retrospectively evaluated (Berlin method), for the presence of acute and structural SIJ changes. A telephone questionnaire focusing on pain characterization, co-morbidities, and clinical outcome was conducted with 52 subjects. Findings were correlated with pregnancy week/postpartum time and clinical parameters. SIJ-bone marrow edema (BME) and subchondral sclerosis were a prevalent peripartum finding (46/26 % subjects, respectively), and their frequency increased with pregnancy age. Also, BME, joint fluid, capsulitis, and enthesitis total score were correlated with pregnancy age/postpartum time (r = 0.2-0.31, P = 0.013-0.036). Significant correlation was noted between BME and subchondral sclerosis scores (r = 0.485, P < 0.0001). A sizable proportion of women showed diffuse SIJ BME (7.6 %) and this correlated with slower resolution of symptoms. Indeed, in half of the cases in which MRI was performed due to pregnancy-induced low-back pain (LBP) and diffuse BME was found-spondyloarthropathy ensued. In conclusion, pregnancy and puerperium are associated with a host of acute findings in and around the SIJ, including BME, capsulitis, and enthesitis, reflecting most probably, mechanical load and hormonal changes. While the vast majority of symptoms abate within weeks to several months postpartum, 3.8 % of women go on to develop spondyloarthropathy. Diffuse SIJ BME and the presence of risk factors for spondyloarthropathy are predictive of a chronic course. PMID:26006255

  1. FACET: SLAC___s New User Facility

    SciTech Connect

    Clarke, C.I.; Decker, F.-J.; England, R.J.; Erickson, R.A.; Hast, C.; Hogan, M.J.; Li, S.Z.; Litos, M.D.; Nosochkov, Y.; Seeman, J.T.; Sheppard, J.; Wienands, U.; Woodley, M.; Yocky, G.; /SLAC

    2012-05-16

    FACET (Facility for Advanced Accelerator Experimental Tests) is a new User Facility at SLAC National Accelerator Laboratory. The first User Run started in spring 2012 with 20 GeV, 3 nC electron beams. The facility is designed to provide short (20 {micro}m) bunches and small (20 {micro}m wide) spot sizes, producing uniquely high power beams. FACET supports studies from many fields but in particular those of Plasma Wakefield Acceleration and Dielectric Wakefield Acceleration. The creation of drive and witness bunches and shaped bunch profiles is possible with 'Notch' Collimation. FACET is also a source of THz radiation for material studies. Positrons will be available at FACET in future user runs. We present the User Facility and the available tools and opportunities for future experiments.

  2. Stability of crystal facets in gold nanorods.

    PubMed

    Katz-Boon, Hadas; Walsh, Michael; Dwyer, Christian; Mulvaney, Paul; Funston, Alison M; Etheridge, Joanne

    2015-03-11

    Metal nanocrystals can be grown in a variety of shapes through the modification of surface facet energies via surfactants. However, the surface facets are only a few atoms wide, making it extremely challenging to measure their geometries and energies. Here, we locate and count atoms in Au nanorods at successive time intervals using quantitative scanning transmission electron microscopy. This enables us to determine the atomic-level geometry and the relative stability of the facets and to expound their relationship to the overall three-dimensional nanocrystal shape and size. We reveal coexisting high- and low-index facets with comparable stability and dimensions and find the geometry of the nanorods is remarkably stable, despite significant atom movements. This information provides unique insights into the mechanisms that govern growth kinetics and nanocrystal morphology. PMID:25658226

  3. FACET: Future ATM Concepts Evaluation Tool

    NASA Technical Reports Server (NTRS)

    Bilmoria, Karl D.; Banavar, Sridhar; Chatterji, Gano B.; Sheth, Kapil S.; Grabbe, Shon

    2000-01-01

    FACET (Future ATM Concepts Evaluation Tool) is an Air Traffic Management research tool being developed at the NASA Ames Research Center. This paper describes the design, architecture and functionalities of FACET. The purpose of FACET is to provide E simulation environment for exploration, development and evaluation of advanced ATM concepts. Examples of these concepts include new ATM paradigms such as Distributed Air-Ground Traffic Management, airspace redesign and new Decision Support Tools (DSTs) for controllers working within the operational procedures of the existing air traffic control system. FACET is currently capable of modeling system-wide en route airspace operations over the contiguous United States. Airspace models (e.g., Center/sector boundaries, airways, locations of navigation aids and airports) are available from databases. A core capability of FACET is the modeling of aircraft trajectories. Using round-earth kinematic equations, aircraft can be flown along flight plan routes or great circle routes as they climb, cruise and descend according to their individual aircraft-type performance models. Performance parameters (e.g., climb/descent rates and speeds, cruise speeds) are obtained from data table lookups. Heading, airspeed and altitude-rate dynamics are also modeled. Additional functionalities will be added as necessary for specific applications. FACET software is written in Java and C programming languages. It is platform-independent, and can be run on a variety of computers. FACET has been designed with a modular software architecture to enable rapid integration of research prototype implementations of new ATM concepts. There are several advanced ATM concepts that are currently being implemented in FACET airborne separation assurance, dynamic density predictions, airspace redesign (re-sectorization), benefits of a controller DST for direct-routing, and the integration of commercial space transportation system operations into the U.S. National

  4. MultiFacet: A Faceted Interface for Browsing Large Multimedia Collections

    SciTech Connect

    Henry, Michael J.; Hampton, Shawn D.; Endert, Alexander; Roberts, Ian E.; Payne, Deborah A.

    2013-10-31

    Faceted browsing is a common technique for exploring collections where the data can be grouped into a number of pre-defined categories, most often generated from textual metadata. Historically, faceted browsing has been applied to a single data type such as text or image data. However, typical collections contain multiple data types, such as information from web pages that contain text, images, and video. Additionally, when browsing a collection of images and video, facets are often created based on the metadata which may be incomplete, inaccurate, or missing altogether instead of the actual visual content contained within those images and video. In this work we address these limitations by presenting MultiFacet, a faceted browsing interface that supports multiple data types. MultiFacet constructs facets for images and video in a collection from the visual content using computer vision techniques. These visual facets can then be browsed in conjunction with text facets within a single interface to reveal relationships and phenomena within multimedia collections. Additionally, we present a use case based on real-world data, demonstrating the utility of this approach towards browsing a large multimedia data collection.

  5. Injury mechanisms of the ligamentous cervical C2-C3 Functional Spinal Unit to complex loading modes: Finite Element study.

    PubMed

    Mustafy, Tanvir; Moglo, Kodjo; Adeeb, Samer; El-Rich, Marwan

    2016-01-01

    The cervical spine sustains high rate complex loading modes during Motor Vehicle Crashes (MVCs) which may produce severe injuries accompanied with soft and/or hard tissue failure. Although previous numerical and experimental studies have provided insights on the cervical spine behavior under various loading scenarios, its response to complex impact loads and the resulting injury mechanisms are not fully understood. A validated Finite Element (FE) model of the ligamentous cervical C2-C3 Functional Spinal Unit (FSU) was utilized to assess the spinal response to six combined impact loading modes; flexion-extension combined with compression and distraction, and lateral bending and axial rotation combined with distraction. The FE model used time and rate-dependent material laws which permit assessing bone fracture and ligament failure. Spinal load-sharing, stresses in the spinal components, intradiscal pressure (IDP) change in the nucleus as well as contact pressure in the facet joints were predicted. Bone and ligaments failure occurrence and initiation instants were investigated. Results showed that spinal load-sharing varied with loading modes. Lateral bending combined with distraction was the most critical loading mode as it increased stresses and strains significantly and produced failure in most of the spinal components compared to other modes. The facet joints and surrounding cancellous bone as well as ligaments particularly the capsular (CL) and flavum (FL) ligaments were the most vulnerable structures to rapid flexion-extension, axial rotation and lateral bending combined with distraction or compression. The excessive stress and strain resulted from these loading modes produced rupture of the CL and FL ligaments and failure in the cancellous bone. The detection of failure initiation as well as fracture assessment demonstrated the vulnerability of ligaments to tensile combined loads and the major contribution of the bony structures in resisting compressive

  6. An investigation into the effect of varying joint aperture and nature of surface on pre-splitting

    SciTech Connect

    Tariq, S.M.; Worsey, P.N.

    1996-12-01

    Presplitting is now a universally accepted perimeter control technique in rock excavation. The success of presplitting and the smoothness and integrity of the resulting perimeter is largely dependent on the nature of joints in any given formation. Many facets of jointing have been previously investigated. The results of the effects of joints frequency and spatial positioning were presented by the authors at the ISEE annual meeting last year. This paper includes the results of further research into the mechanism of presplit blasting being carried out at the Rock Mechanics and Explosives Research Center of the University of Missouri-Rolla. The results of experimental model testing carried out in concrete blocks are presented. The research comprised of modeling both closed and open joints between 3/8 inch blastholes loaded with 15-grain per foot PETN detonating cord. The closed joints were (a) simple (rough) machine-cut and (b) surface ground (smooth-matching). The precision ground joints were modeled to simulate tight fractures as found in real rock mass. Precision spacers of varying thicknesses were used to create opening between the joint surfaces. It was found that precision ground joints have no significant effect on the maximum blasthole spacing up to two joints, and act like a continuous medium. This is because ground surfaces provide a relatively perfect match thereby transmitting most of the energy through the joint. However beyond two ground joints, the effects of attenuation is evident and the maximum blasthole spacing has to be reduced to obtain a presplit plane. A simple machine cut joint, on the other hand, has some undulations that results in loss of energy, making it necessary to bring the blastholes closer to achieve a presplit plane (for up to two joints). It was observed that a ground joint with spacer thickness of 0.012 inch behaves like a free surface.

  7. An Initial Facet Analysis of the FYCSP Word Attack Test.

    ERIC Educational Resources Information Center

    Besel, Ronald

    The concepts "facet analysis,""facet design," and "facet structure" are defined. The FYCSP (First Year Communication Skills Program) Word Attack Test is analyzed in terms of two related facet structures. Stepwise linear regression is used to predict distractor attractiveness. Hypotheses suggested by Guttman relating distractor attractiveness to…

  8. Butt Joint Tool Commissioning

    SciTech Connect

    Martovetsky, N N

    2007-12-06

    ITER Central Solenoid uses butt joints for connecting the pancakes in the CS module. The principles of the butt joining of the CICC were developed by the JAPT during CSMC project. The difference between the CSMC butt joint and the CS butt joint is that the CS butt joint is an in-line joint, while the CSMC is a double joint through a hairpin jumper. The CS butt joint has to carry the hoop load. The straight length of the joint is only 320 mm, and the vacuum chamber around the joint has to have a split in the clamp shell. These requirements are challenging. Fig.1 presents a CSMC joint, and Fig.2 shows a CS butt joint. The butt joint procedure was verified and demonstrated. The tool is capable of achieving all specified parameters. The vacuum in the end was a little higher than the target, which is not critical and readily correctable. We consider, tentatively that the procedure is established. Unexpectedly, we discover significant temperature nonuniformity in the joint cross section, which is not formally a violation of the specs, but is a point of concern. All testing parameters are recorded for QA purposes. We plan to modify the butt joining tool to improve its convenience of operation and provide all features necessary for production of butt joints by qualified personnel.

  9. Joint swelling

    MedlinePlus

    Swelling of a joint ... Joint swelling may occur along with joint pain . The swelling may cause the joint to appear larger or abnormally shaped. Joint swelling can cause pain or stiffness. After an ...

  10. Facet development for a faceted stretched-membrane dish by Solar Kinetics, Inc

    SciTech Connect

    Schertz, P.T.; Brown, D.C.; Konnerth, A. III )

    1991-07-01

    A 3.6-meter diameter stretched-membrane optical facet for a parabolic dish has been successfully designed and demonstrated under contract with Sandia National Laboratories. Twelve facets identical to them will be used to make the lightweight reflector of the dish. The project goal of 2.5-mrad surface accuracy was met with each of the two full-sized prototypes, and accuracies of as low as 1.1 mrad were achieved. The facet weight is 11.7 kg/m{sup 2} (2.4lbs/ft{sup 2}). The facet is similar in construction to the successful stretched-membrane heliostat; it has two thin metal membranes attached to a ring. However, the front membrane for this facet is plastically formed at the factor in order to achieve a shorter facet f/D (approximately 3.0). A passive tether restrains the from membrane when not in operation, that is, when the stabilizing vacuum is off. The optical surface is achieved with a silvered-acrylic film laminated to the metal membrane. The facet is expected to cost $55.40/m{sup 2} at a production rate of 10,000 facets per year and $115, 000/m{sup 2}-at a production rate of 500 facets a year. Several key issues have been resolved. Stress concentrations due to seams in the reflective laminate did not cause membrane rupture during forming as they have for dishes with lower focal length-to-diameter ratios. The laminate survived the forming process and simulated operation without deterioration. The optical effect of the tether on the membrane was tested and found to be very small. Most important, highly accurate shapes were obtained using a simple forming procedure. Additional tests are needed to demonstrate process repeatablility and facet performance in typical operating conditions. 18 refs., 36 figs., 11 tabs.

  11. Development of gait performance and dynamic hip and knee joint loading after containment improving surgery in patients with Legg-Calvé-Perthes disease.

    PubMed

    Stief, Felix; Schmidt, André; Adolf, Stefanie; Kremer, Laura; Brkic, Moamer; Meurer, Andrea

    2016-06-01

    Current surgery outcome evaluations in patients with Legg-Calvé-Perthes disease (LCPD) are usually based on static radiological changes. The aim of the present study was to assess the development of characteristic gait parameters and passive hip range of motion (ROM) measurements during the postoperative period up to healed stage of the femoral head represented by Stulberg classification. Twelve children (10 male, 2 female) with unilateral diagnosis of LCPD and 19 healthy control subjects at the same age participated in this prospective longitudinal study. Instrumented gait analysis was performed preoperatively, 13.4 (±1.7), and 28.0 (±4.4) months postoperatively. At final follow-up, the mean leg length of the involved side was reduced by 1.10 (±0.53)cm compared to the non-involved side. In addition, a significant reduction in maximum knee flexion (-26%, p=0.037) and knee flexion/extension ROM (-26%, p=0.017) in stance was still present in the patient group compared to controls indicating a "stiff knee gait pattern". In contrast, the sagittal plane hip parameters, the ipsilateral trunk lean toward the involved stance limb, and the knee and hip joint loading during gait normalized during the postoperative period. The results of the present study should motivate further exploration if patients with LCPD stiffen their knees to compensate for leg length discrepancy. Besides the standard radiological evaluation of the surgery outcome, instrumented gait analysis is a valuable method of recording functional deficits and early recognition of the need for physiotherapeutic treatment or insole supply in patients with LCPD. PMID:27264403

  12. The facets of relativistic quantum field theory

    NASA Astrophysics Data System (ADS)

    Dosch, H. G.; Müller, V. F.

    2010-04-01

    Relativistic quantum field theory is generally recognized to form the adequate theoretical frame for subatomic physics, with the Standard Model of Particle Physics as a major achievement. We point out that quantum field theory in its present form is not a monolithic theory, but rather consists of distinct facets, which aim at a common ideal goal. We give a short overview of the strengths and limitations of these facets. We emphasize the theory-dependent relation between the quantum fields, and the basic objects in the empirical domain, the particles. Given the marked conceptual differences between the facets, we argue to view these, and therefore also the Standard Model, as symbolic constructions. We finally note that this view of physical theories originated in the 19th century and is related to the emergence of the classical field as an autonomous concept.

  13. The facets of relativistic quantum field theory

    NASA Astrophysics Data System (ADS)

    Dosch, H. G.; Müller, V. F.

    2011-04-01

    Relativistic quantum field theory is generally recognized to form the adequate theoretical frame for subatomic physics, with the Standard Model of Particle Physics as a major achievement. We point out that quantum field theory in its present form is not a monolithic theory, but rather consists of distinct facets, which aim at a common ideal goal. We give a short overview of the strengths and limitations of these facets. We emphasize the theory-dependent relation between the quantum fields, and the basic objects in the empirical domain, the particles. Given the marked conceptual differences between the facets, we argue to view these, and therefore also the Standard Model, as symbolic constructions. We finally note that this view of physical theories originated in the 19th century and is related to the emergence of the classical field as an autonomous concept.

  14. Alignment and focus of mirrored facets of a heliosat

    SciTech Connect

    Yellowhair, Julius E; Ho, Clifford Kuofei; Diver, Richard B; Moss, Timothy A

    2013-11-12

    Various technologies pertaining to aligning and focusing mirrored facets of a heliostat are described herein. Updating alignment and/or focus of mirrored facets is undertaken through generation of a theoretical image, wherein the theoretical image is indicative of a reflection of the target via the mirrored facets when the mirrored facets are properly aligned. This theoretical image includes reference points that are overlaid on an image of the target as reflected by the mirrored facets of the heliostat. A technician adjusts alignment/focus of a mirrored facet by causing reflected reference markings to become aligned with the reference points in the theoretical image.

  15. A Model of Job Facet Satisfaction.

    ERIC Educational Resources Information Center

    Conway, Patricia G.; And Others

    1987-01-01

    Elements of the job that lead to overall job satisfaction were surveyed among public employees. The 17-facet model included promotion, training, supervisor, upper management, organization of work tasks, work stress, work challenge and autonomy, physical work space and equipment, work group, organizational structure, pay, etc. (Author/MH)

  16. Perovskite solar cells: Different facets of performance

    NASA Astrophysics Data System (ADS)

    Eperon, Giles E.; Ginger, David S.

    2016-08-01

    The electronic properties of halide perovskites vary significantly between crystalline grains, but the impact of this heterogeneity on solar cell performance is unclear. Now, this variability is shown to limit the photovoltaic properties of solar cells, and its origins are linked to differing properties between crystal facets.

  17. Problem of time: facets and Machian strategy.

    PubMed

    Anderson, Edward

    2014-10-01

    The problem of time is that "time" in each of ordinary quantum theory and general relativity are mutually incompatible notions. This causes difficulties in trying to put these two theories together to form a theory of quantum gravity. The problem of time has eight facets in canonical approaches. I clarify that all but one of these facets already occur at the classical level, and reconceptualize and re-name some of these facets as follows. The frozen formalism problem becomes temporal relationalism, the thin sandwich problem becomes configurational relationalism, via the notion of best matching. The problem of observables becomes the problem of beables, and the functional evolution problem becomes the constraint closure problem. I also outline how each of the global and multiple-choice problems of time have their own plurality of facets. This article additionally contains a local resolution to the problem of time at the conceptual level and which is actually realizable for the relational triangle and minisuperspace models. This resolution is, moreover, Machian, and has three levels: classical, semiclassical, and a combined semiclassical-histories-timeless records scheme. I end by delineating the current frontiers of this program toward resolution of the problem of time in the cases of full general relativity and of slightly inhomogeneous cosmology. PMID:25266113

  18. Facet-Selective Epitaxy of Compound Semiconductors on Faceted Silicon Nanowires.

    PubMed

    Mankin, Max N; Day, Robert W; Gao, Ruixuan; No, You-Shin; Kim, Sun-Kyung; McClelland, Arthur A; Bell, David C; Park, Hong-Gyu; Lieber, Charles M

    2015-07-01

    Integration of compound semiconductors with silicon (Si) has been a long-standing goal for the semiconductor industry, as direct band gap compound semiconductors offer, for example, attractive photonic properties not possible with Si devices. However, mismatches in lattice constant, thermal expansion coefficient, and polarity between Si and compound semiconductors render growth of epitaxial heterostructures challenging. Nanowires (NWs) are a promising platform for the integration of Si and compound semiconductors since their limited surface area can alleviate such material mismatch issues. Here, we demonstrate facet-selective growth of cadmium sulfide (CdS) on Si NWs. Aberration-corrected transmission electron microscopy analysis shows that crystalline CdS is grown epitaxially on the {111} and {110} surface facets of the Si NWs but that the Si{113} facets remain bare. Further analysis of CdS on Si NWs grown at higher deposition rates to yield a conformal shell reveals a thin oxide layer on the Si{113} facet. This observation and control experiments suggest that facet-selective growth is enabled by the formation of an oxide, which prevents subsequent shell growth on the Si{113} NW facets. Further studies of facet-selective epitaxial growth of CdS shells on micro-to-mesoscale wires, which allows tuning of the lateral width of the compound semiconductor layer without lithographic patterning, and InP shell growth on Si NWs demonstrate the generality of our growth technique. In addition, photoluminescence imaging and spectroscopy show that the epitaxial shells display strong and clean band edge emission, confirming their high photonic quality, and thus suggesting that facet-selective epitaxy on NW substrates represents a promising route to integration of compound semiconductors on Si. PMID:26057208

  19. Bone Scans Are Reliable for the Identification of Lumbar Disk and Facet Pathology

    PubMed Central

    Malham, Gregory M.; Parker, Rhiannon M.; Ballok, Zita E.; Goss, Ben; Diwan, Ashish D.; Uribe, Juan S.

    2014-01-01

    Study Design Surgeon survey. Objective To evaluate the reliability of bone single-photon emission computed tomography (SPECT) versus bone SPECT images co-registered with computed tomography (bone SPECT-CT) by analyzing interobserver agreement for identification of the anatomical location of technetium99m-labeled oxidronate uptake in the lumbar disk and/or facet joint. Methods Seven spine surgeons interpreted 20 bone scans: 10 conventional black-and-white tomograms (bone SPECT) and 10 color-graded bone SPECT-CT scans. Each surgeon was asked to identify the location of any diagnostically relevant uptake in the disk and/or facet joint between L1 and S1. Reliability was evaluated using the free-marginal kappa statistic, and the level of agreement was assessed using the Landis and Koch interpretation. Results Conventional bone SPECT scans and bone SPECT-CT scans were reliable for the identification of diagnostically relevant uptake, with bone SPECT-CT having higher reliability (kappa = 0.72) than bone SPECT alone (0.59). Bone SPECT and bone SPECT-CT were also reliable in identifying disk pathology, with kappa values of 0.72 and 0.81, respectively. However, bone SPECT-CT was more reliable (0.81) than bone SPECT (0.60) when identifying facet disease. Conclusions For the identification of disk pathology, it is reasonable to use either conventional bone SPECT or bone SPECT-CT; however, bone SPECT-CT is more reliable for facet joint pathology. PMID:25648168

  20. Effect of Retrograde Reaming for Tibiotalocalcaneal Arthrodesis on Subtalar Joint Destruction: A Cadaveric Study.

    PubMed

    Lowe, Jason A; Routh, Lucas K; Leary, Jeffrey T; Buzhardt, Paul C

    2016-01-01

    Recent published data have suggested successful union of subtalar and tibiotalar joints without formal debridement during tibiotalocalcaneal (TTC) fusion procedures. Although previous studies have reported on the importance of the proper guidewire starting point and trajectory to obtain appropriate hindfoot alignment for successful fusion, to our knowledge, no studies have quantified the amount of articular damage to the subtalar joint with retrograde reaming. We hypothesized that reaming would destroy >50% of the posterior facet of the subtalar joint. The bilateral lower extremities of 5 cadavers were obtained and the subtalar joints exposed. Retrograde TTC nail guidewires were inserted, and a 12-mm reamer was passed through the subtalar and ankle joints. Pre- and postreaming images of the subtalar joint were obtained to compare the amount of joint destruction after reaming. We found an average of 5.89% articular destruction of the talar posterior facet and an average of 4.01% articular destruction of the posterior facet of the calcaneus. No damage to the middle facets of the subtalar joint was observed. TTC nailing is a successful procedure for ankle and subtalar joint fusion. Published studies have reported successful subtalar union using TTC nailing without formal open debridement of the subtalar joint, preserving the soft tissue envelope. TTC nail insertion using a 12-mm reamer will destroy 5.89% and 4.01% of the respective talar and calcaneal posterior facets of the subtalar joint. PMID:26372551

  1. Results from Plasma Wakefield Experiments at FACET

    SciTech Connect

    Li, S.Z.; Clarke, C.I.; England, R.J.; Frederico, J.; Gessner, S.J.; Hogan, M.J.; Jobe, R.K.; Litos, M.D.; Walz, D.R.; Muggli, P.; An, W.; Clayton, C.E.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.; Tochitsky, S.; Adli, E.; /U. Oslo

    2011-12-13

    We report initial results of the Plasma Wakefield Acceleration (PWFA) Experiments performed at FACET - Facility for Advanced aCcelertor Experimental Tests at SLAC National Accelerator Laboratory. At FACET a 23 GeV electron beam with 1.8 x 10{sup 10} electrons is compressed to 20 {mu}m longitudinally and focused down to 10 {mu}m x 10 {mu}m transverse spot size for user driven experiments. Construction of the FACET facility completed in May 2011 with a first run of user assisted commissioning throughout the summer. The first PWFA experiments will use single electron bunches combined with a high density lithium plasma to produce accelerating gradients > 10 GeV/m benchmarking the FACET beam and the newly installed experimental hardware. Future plans for further study of plasma wakefield acceleration will be reviewed. The experimental hardware and operation of the plasma heat-pipe oven have been successfully commissioned. Plasma wakefield acceleration was not observed because the electron bunch density was insufficient to ionize the lithium vapor. The remaining commissioning time in summer 2011 will be dedicated to delivering the FACET design parameters for the experimental programs which will begin in early 2012. PWFA experiments require the shorter bunches and smaller transverse sizes to create the plasma and drive large amplitude wakefields. Low emittance and high energy will minimize head erosion which was found to be a limiting factor in acceleration distance and energy gain. We will run the PWFA experiments with the design single bunch conditions in early 2012. Future PWFA experiments at FACET are discussed in [5][6] and include drive and witness bunch production for high energy beam manipulation, ramped bunch to optimize tranformer ratio, field-ionized cesium plasma, preionized plasmas, positron acceleration, etc.. We will install a notch collimator for two-bunch operation as well as new beam diagnostics such as the X-band TCAV [7] to resolve the two bunches

  2. Perceptions of Overall Job Satisfaction and Facet Satisfaction of Principals.

    ERIC Educational Resources Information Center

    Holdaway, Edward A.; Johnson, Neil A.

    Learned opinion supports the relevance of satisfaction with job facets in studies of job satisfaction, but an analysis of the perceived importance of these facets concerning overall job satisfaction in education has largely been ignored. The relationships among Alberta (Canada) elementary and junior high school principals' job facet perceptions…

  3. Formulation and Application of the Generalized Multilevel Facets Model

    ERIC Educational Resources Information Center

    Wang, Wen-Chung; Liu, Chih-Yu

    2007-01-01

    In this study, the authors develop a generalized multilevel facets model, which is not only a multilevel and two-parameter generalization of the facets model, but also a multilevel and facet generalization of the generalized partial credit model. Because the new model is formulated within a framework of nonlinear mixed models, no efforts are…

  4. Facet Modelling: An Approach to Flexible and Integrated Conceptual Modelling.

    ERIC Educational Resources Information Center

    Opdahl, Andreas L.; Sindre, Guttorm

    1997-01-01

    Identifies weaknesses of conceptual modelling languages for the problem domain of information systems (IS) development. Outlines an approach called facet modelling of real-world problem domains to deal with the complexity of contemporary analysis problems. Shows how facet models can be defined and visualized; discusses facet modelling in relation…

  5. Identifying Facets of Problem Solving in Mathematics Instruction.

    ERIC Educational Resources Information Center

    Klieme, Eckhard; Clausen, Marten

    Facets of problem solving instruction (PSI) were studied in German mathematics classrooms. Nine different facets of PSI were identified from the research literature, and a video rating form was developed to assess these facets and teacher effectiveness. Videotaped mathematics lessons (n=147) for German eighth graders from the sample for the Third…

  6. Does lumbar facet arthrosis precede disc degeneration? A postmortem study.

    PubMed

    Eubanks, Jason David; Lee, Michael J; Cassinelli, Ezequiel; Ahn, Nicholas U

    2007-11-01

    It is believed lumbar degeneration begins in the disc, where desiccation and collapse lead to instability and compensatory facet arthrosis. We explored the contrary contention that facet degeneration precedes disc degeneration by examining 647 skeletal lumbar spines. Using facet osteophytosis as a measure of facet degeneration and vertebral rim osteophytosis as a measure of disc degeneration, we assumed bone degeneration in both locations equally reflected the progression of those in the soft tissues. We graded arthrosis Grade 0 to 4 on a continuum from no arthritis to ankylosis. The data were analyzed for different age groups to examine patterns of degeneration with age. Specimens younger than 30 years of age had a higher prevalence of facet osteophytosis compared with vertebral rim osteophotosis at L1-L2 and L2-L3. Specimens aged 30 to 39 years showed more facet osteophytosis than vertebral rim osteophytosis at L4-L5. Specimens older than 40 years, however, showed more vertebral rim osteophytosis compared with facet osteophytosis at all levels except L4-L5 and L5-S1. This skeletal study suggests facet osteophytosis appears early in the degenerative process, preceding vertebral rim osteophytosis of degenerating intervertebral discs. However, once facets begin deteriorating with age, vertebral rim osteophytosis overtakes continued facet osteophytosis. These data challenge the belief that facet osteophytosis follows vertebral rim osteophytosis; rather, it appears vertebral rim osteophytosis progresses more rapidly in later years, but facet osteophotosis occurs early, predominating in younger individuals. PMID:17767079

  7. Zeroing In on Mindfulness Facets: Similarities, Validity, and Dimensionality across Three Independent Measures

    PubMed Central

    Siegling, Alex B.; Petrides, K. V.

    2016-01-01

    The field of mindfulness has seen a proliferation of psychometric measures, characterised by differences in operationalisation and conceptualisation. To illuminate the scope of, and offer insights into, the diversity apparent in the burgeoning literature, two distinct samples were used to examine the similarities, validity, and dimensionality of mindfulness facets and subscales across three independent measures: the Five Facet Mindfulness Questionnaire (FFMQ), Philadelphia Mindfulness Scale (PHLMS), and Toronto Mindfulness Scale (TMS). Results revealed problematic associations of FFMQ Observe with the other FFMQ facets and supported a four-factor structure (omitting this facet), while disputing the originally envisaged five-factor model; thus, solidifying a pattern in the literature. Results also confirmed the bidimensional nature of the PHLMS and TMS subscales, respectively. A joint Confirmatory Factor Analysis showed that PHLMS Acceptance could be assimilated within the FFMQ’s four-factor model (as a distinct factor). The study offers a way of understanding interrelationships between the available mindfulness scales, so as to help practitioners and researchers make a more informed choice when conceptualising and operationalising mindfulness. PMID:27055017

  8. Rough surface scattering based on facet model

    NASA Technical Reports Server (NTRS)

    Khamsi, H. R.; Fung, A. K.; Ulaby, F. T.

    1974-01-01

    A model for the radar return from bare ground was developed to calculate the radar cross section of bare ground and the effect of the frequency averaging on the reduction of the variance of the return. It is shown that, by assuming that the distribution of the slope to be Gaussian and that the distribution of the length of the facet to be in the form of the positive side of a Gaussian distribution, the results are in good agreement with experimental data collected by an 8- to 18-GHz radar spectrometer system. It is also shown that information on the exact correlation length of the small structure on the ground is not necessary; an effective correlation length may be calculated based on the facet model and the wavelength of the incident wave.

  9. How faceted liquid droplets grow tails

    PubMed Central

    Guttman, Shani; Sapir, Zvi; Schultz, Moty; Butenko, Alexander V.; Ocko, Benjamin M.; Deutsch, Moshe; Sloutskin, Eli

    2016-01-01

    Liquid droplets, widely encountered in everyday life, have no flat facets. Here we show that water-dispersed oil droplets can be reversibly temperature-tuned to icosahedral and other faceted shapes, hitherto unreported for liquid droplets. These shape changes are shown to originate in the interplay between interfacial tension and the elasticity of the droplet’s 2-nm-thick interfacial monolayer, which crystallizes at some T = Ts above the oil’s melting point, with the droplet’s bulk remaining liquid. Strikingly, at still-lower temperatures, this interfacial freezing (IF) effect also causes droplets to deform, split, and grow tails. Our findings provide deep insights into molecular-scale elasticity and allow formation of emulsions of tunable stability for directed self-assembly of complex-shaped particles and other future technologies. PMID:26733673

  10. How faceted liquid droplets grow tails.

    PubMed

    Guttman, Shani; Sapir, Zvi; Schultz, Moty; Butenko, Alexander V; Ocko, Benjamin M; Deutsch, Moshe; Sloutskin, Eli

    2016-01-19

    Liquid droplets, widely encountered in everyday life, have no flat facets. Here we show that water-dispersed oil droplets can be reversibly temperature-tuned to icosahedral and other faceted shapes, hitherto unreported for liquid droplets. These shape changes are shown to originate in the interplay between interfacial tension and the elasticity of the droplet's 2-nm-thick interfacial monolayer, which crystallizes at some T = Ts above the oil's melting point, with the droplet's bulk remaining liquid. Strikingly, at still-lower temperatures, this interfacial freezing (IF) effect also causes droplets to deform, split, and grow tails. Our findings provide deep insights into molecular-scale elasticity and allow formation of emulsions of tunable stability for directed self-assembly of complex-shaped particles and other future technologies. PMID:26733673

  11. Interventional radiology in bone and joint

    SciTech Connect

    Bard, M.; Laredo, J.D.

    1988-01-01

    Recent radiologic procedures in bone and joints, some of which eliminate the need for surgery are exposed, including: trephine biopsies of the thoracic and lumbar spine, sacro-iliac joints, peripheral bones synovial membrane and soft tissues, using either fluoroscopic echographic or CT guidance - chemonucleolysis - vascular embolization of skeletal tumors and management of vertebral hemangiomas - selective steroid injection in a broad spectrum of diseases including vertebral facet syndrome, cervicobrachial nerve root pain, rotator cuff calcium deposit, bone cysts.

  12. FACET: The New User Facility at SLAC

    SciTech Connect

    Clarke, C.I.; Decker, F.J.; Erikson, R.; Hast, C.; Hogan, M.J.; Iverson, R.; Li, S.Z.; Nosochkov, Y.; Phinney, N.; Sheppard, J.; Wienands, U.; Woodley, M.; Yocky, G.; Seryi, A.; Wittmer, W.; /Michigan State U.

    2011-12-13

    FACET (Facility for Advanced Accelerator and Experimental Tests) is a new User Facility at SLAC National Accelerator Laboratory. Its high power electron and positron beams make it a unique facility, ideal for beam-driven Plasma Wakefield Acceleration studies. The first 2 km of the SLAC linac produce 23 GeV, 3.2 nC electron and positron beams with short bunch lengths of 20 {mu}m. A final focusing system can produce beam spots 10 {mu}m wide. User-aided Commissioning took place in summer 2011 and FACET will formally come online in early 2012. We present the User Facility, the current features, planned upgrades and the opportunities for further experiments. Accelerators are our primary tool for discovering the fundamental laws to the universe. Each new frontier we probe requires a new, more powerful method. Accelerators are therefore increasing in size and cost. The future of this field requires new accelerating techniques that can reach the high energies required over shorter distances. New concepts for high gradient acceleration include utilizing the wakes in plasma and dielectric and metallic structures. FACET was built to provide a test bed for novel accelerating concepts with its high charge and highly compressed beams. As a test facility unlike any other, it has also attracted groups interested in beam diagnostic techniques and terahertz studies. The first phase of the construction was completed in May 2011. Beam commissioning began in June and was interleaved with the installation of five experiments. Users were invited to aid with the commissioning for the month of August during which time experimental hardware and software were checked out and some first measurements were taken. FACET is currently in the process of becoming a Department of Energy User Facility for High Energy Physics.

  13. Shell structure in faceted metal clusters

    NASA Astrophysics Data System (ADS)

    Pavloff, Nicolas; Creagh, Stephen C.

    1993-12-01

    We study the quantized electronic energy levels in a three-dimensional icosahedral billiard modeling a faceted metal cluster. The first 2000 levels are determined numerically. The magic numbers are compared with experimental data and with the results for a spherical model. We discuss the supershell structure and propose its study as a test of cluster sphericity. We compare our results with the predictions of the semiclassical trace formula and point out the relevance of diffractive orbits.

  14. It's in the mix: psychological distress differs between combinations of alexithymic facets

    PubMed Central

    Alkan Härtwig, Elif; Crayen, Claudia; Heuser, Isabella; Eid, Michael

    2014-01-01

    Alexithymia is a personality trait characterized by difficulties in identifying, describing, and communicating one's emotions. The aim of the present study is to examine the usefulness of a typological approach considering the interaction between distinct alexithymic features within a population of high-alexithymic German adults (N = 217). Latent profile analysis (LPA) was employed to test for possible underlying profiles. A 3-profile solution showed the best fit: The profiles can be described as (1) “low”: lower load on all facets of alexithymia, (2) “mixed”: specific problems on identifying emotions, and (3) “high”: higher load on all facets of alexithymia. Moreover, this study tested how these profiles differed in psychological distress. “Mixed” profile, with specific problems on identifying emotions showed the highest levels of psychological distress. The present study suggests the importance of a specific combination of alexithymic features, rather than total alexithymia scores, as a risk factor for psychological distress. PMID:25429275

  15. Facet coatings for nonhermetically packaged lasers

    NASA Astrophysics Data System (ADS)

    Caballero, J. A.; He, C.; Djavani-Tabrizi, S.; Yin, T.; Mallard, R.; Das, S. R.

    2004-05-01

    Nonhermetic packaging is one avenue of reducing the module cost of optical devices; however, this requires the coatings applied to the facets of lasers and modulators to be highly stable and impervious to the effects of high humidity under high temperature/high power operating conditions. We have developed two types of facet coatings for nonhermetic applications. One involves electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) of a SiNx cap layer and the other utilizes ion beam deposition (IBD) of a Ta2O5 cap layer, both on top of a two-layer SiO2/a-Si high-reflectance (HR) coating deposited on the facets of Fabry-Perot (F-P) ridge waveguide (RWG) lasers operating at 1310 nm. The lasers were aged under 85 °C/85% relative humidity (RH) conditions and ex situ tested using drive currents of 10-20 mA (subthreshold) and 80-120 mA operating currents (Iop). The output power-current-voltage (L-I-V) tests were conducted at room temperature and at various time intervals up to 5000 h. For comparison, tests were also done on devices aged in a dry oven. .

  16. JPL tests of a LaJet concentrator facet

    NASA Technical Reports Server (NTRS)

    Dennison, E. W.; Argoud, M. J.

    1983-01-01

    A LaJet Energy Company (LEC) concentrator facet, 60 in. in diameter, was tested for imaging quality. The following two methods were used: (1) autofocus tests with a point source of light at the facet's radius of curvature; and (2) tests with the Sun close to the horizon as a distant source. The tests of the LaJet facet indicate that all of the solar image reflected by an LEC 460 solar concentrator made of like facets should fall within a 9-in. aperture if the outer facets are carefully adjusted. Such a concentrator would have acceptable performance, but complete evaluation must be made with an assembled concentrator.

  17. Nanoparticle growth. Facet development during platinum nanocube growth.

    PubMed

    Liao, Hong-Gang; Zherebetskyy, Danylo; Xin, Huolin; Czarnik, Cory; Ercius, Peter; Elmlund, Hans; Pan, Ming; Wang, Lin-Wang; Zheng, Haimei

    2014-08-22

    An understanding of how facets of a nanocrystal develop is critical for controlling nanocrystal shape and designing novel functional materials. However, the atomic pathways of nanocrystal facet development are mostly unknown because of the lack of direct observation. We report the imaging of platinum nanocube growth in a liquid cell using transmission electron microscopy with high spatial and temporal resolution. The growth rates of all low index facets are similar until the {100} facets stop growth. The continuous growth of the rest facets leads to a nanocube. Our calculation shows that the much lower ligand mobility on the {100} facets is responsible for the arresting of {100} growing facets. These findings shed light on nanocrystal shape-control mechanisms and future design of nanomaterials. PMID:25146287

  18. Use of two-dimensional transmission photoelastic models to study stresses in double-lap bolted joints: Load transfer and stresses in the inner lap

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.

    1980-01-01

    The determination of the stress distribution in the inner lap of double-lap, double-bolt joints using photoelastic models of the joint is discussed. The principal idea is to fabricate the inner lap of a photoelastic material and to use a photoelastically sensitive material for the two outer laps. With this setup, polarized light transmitted through the stressed model responds principally to the stressed inner lap. The model geometry, the procedures for making and testing the model, and test results are described.

  19. Effect of Heat Input Pulse on the Structure and Properties of Welded Joints of Steels Ferritic-Pearlitic Class, Operating Under Low-Frequency Temperature-Force Loading

    NASA Astrophysics Data System (ADS)

    Saraev, Y. N.; Bezborodov, V. P.; Putilova, E. A.

    2015-09-01

    We have investigated the influence of the modes of adaptive pulse-arc welding and surfacing on the structure and physical-mechanical properties of welded joints of steel 09Mn2Si and the surfaced composition of this steel coated with modified powder material of chromium carbide with the submicrocrystalline structure. It is shown that the pulsed mode of welding and surfacing can improve the homogeneity of the structure of the welded joint of steel and surfaced coating and reduce the grain size of metals in both of them. Structural changes lead to the increase in ductility and toughness of the weld metal.

  20. Chemically assisted ion beam etching of laser diode facets on nonpolar and semipolar orientations of GaN

    NASA Astrophysics Data System (ADS)

    Kuritzky, L. Y.; Becerra, D. L.; Saud Abbas, A.; Nedy, J.; Nakamura, S.; DenBaars, S. P.; Cohen, D. A.

    2016-07-01

    We demonstrate a vertical (<1° departure) and smooth (2.0 nm root mean square line-edge roughness (LER)) etch by chemically assisted Ar ion beam etching (CAIBE) in Cl2 chemistry that is suitable for forming laser diode (LD) facets on nonpolar and semipolar oriented III-nitride devices. The etch profiles were achieved with photoresist masks and optimized CAIBE chamber conditions including the platen tilt angle and Cl2 flow rate. Co-loaded studies showed similar etch rates of ∼60 nm min‑1 for (20\\bar{2}\\bar{1}),(20\\bar{2}1), and m-plane orientations. The etched surfaces of LD facets on these orientations are chemically dissimilar (Ga-rich versus N-rich), but were visually indistinguishable, thus confirming the negligible orientation dependence of the etch. Continuous-wave blue LDs were fabricated on the semipolar (20\\bar{2}\\bar{1}) plane to compare CAIBE and reactive ion etch (RIE) facet processes. The CAIBE process resulted in LDs with lower threshold current densities due to reduced parasitic mirror loss compared with the RIE process. The LER, degree of verticality, and model of the 1D vertical laser mode were used to calculate a maximum uncoated facet reflection of 17% (94% of the nominal) for the CAIBE facet. The results demonstrate the suitability of CAIBE for forming high quality facets for high performance nonpolar and semipolar III-N LDs.

  1. High Stability of Faceted Nanotubes and Fullerenes of Multiphase Layered Phosphorus: A Computational Study

    NASA Astrophysics Data System (ADS)

    Guan, Jie; Zhu, Zhen; Tománek, David

    2014-11-01

    We present a paradigm in constructing very stable, faceted nanotube and fullerene structures by laterally joining nanoribbons or patches of different planar phosphorene phases. Our ab initio density functional calculations indicate that these phases may form very stable, nonplanar joints. Unlike fullerenes and nanotubes obtained by deforming a single-phase planar monolayer at substantial energy penalty, we find faceted fullerenes and nanotubes to be nearly as stable as the planar single-phase monolayers. The resulting rich variety of polymorphs allows us to tune the electronic properties of phosphorene nanotubes and fullerenes not only by the chiral index but also by the combination of different phosphorene phases. In selected phosphorene nanotubes, a metal-insulator transition may be induced by strain or by changing the number of walls.

  2. High stability of faceted nanotubes and fullerenes of multi-phase layered phosphorus: A computational study

    NASA Astrophysics Data System (ADS)

    Guan, Jie; Zhu, Zhen; Tomanek, David

    2015-03-01

    We present a paradigm in constructing very stable, faceted nanotube and fullerene structures by laterally joining nanoribbons or patches of different planar phosphorene phases. Our ab initio density functional calculations indicate that these phases may form very stable, non-planar joints. Unlike fullerenes and nanotubes obtained by deforming a single-phase planar monolayer at substantial energy penalty, we find faceted fullerenes and nanotubes to be nearly as stable as the planar single-phase monolayers. The resulting rich variety of polymorphs allows to tune the electronic properties of phosphorene nanotubes (PNTs) and fullerenes not only by the chiral index, but also by the combination of different phosphorene phases. In selected PNTs, a metal-insulator transition may be induced by strain or changing the number of walls. Supported by the National Science Foundation Cooperative Agreement #EEC-0832785, titled ``NSEC: Center for High-rate Nanomanufacturing.''

  3. Shear-Joint Capability Versus Bolt Clearance

    NASA Technical Reports Server (NTRS)

    Lee, H. M.

    1994-01-01

    NASA Technical Memorandum presents theoretical study of relationships between load-bearing capabilities of shear joints that comprise plates clamped together by multiple bolts and clearances between bolts and boltholes in those joints.

  4. [Facets of diagnostics of mentalization in children].

    PubMed

    Juen, Florian

    2014-01-01

    Clinical relevance of variations within the ability to mentalize is usually reported in the field of psychopathology in adults. This might be due to difficulties in methods for empirical assessment of this capacity in children. In this short report the author discusses facets and abilities of how to engage the inner world of young children with story stem techniques and especially how to register variations in the ability to mentalize. Ideas for assessment in early childhood are presented and illustrated along two clinical vignettes. This paper gives a short impression of clinical diagnostics of mentalization in childhood. PMID:25478751

  5. A study of cervical spine kinematics and joint capsule strain in rear impacts using a human FE model.

    PubMed

    Kitagawa, Yuichi; Yasuki, Tsuyoshi; Hasegawa, Junji

    2006-11-01

    Many efforts have been made to understand the mechanism of whiplash injury. Recently, the cervical facet joint capsules have been focused on as a potential site of injury. An experimental approach has been taken to analyze the vertebral motion and to estimate joint capsule stretch that was thought to be a potential cause of pain. The purpose of this study is to analyze the kinematics of the cervical facet joint using a human FE model in order to better understand the injury mechanism. The Total Human Model for Safety (THUMS) was used to visually analyze the local and global kinematics of the spine. Soft tissues in the neck were newly modeled and introduced into THUMS for estimating the loading level in rear impacts. The model was first validated against human test data in the literature by comparing vertebrae motion as well as head and neck responses. Joint capsule strain was estimated from a maximum principal strain output from the elements representing the capsule tissues. A rear-end collision was then simulated using THUMS and a prototype seat model, assuming a delta-V of 25 km/h. The trajectory of the vertebrae was analyzed in a local coordinate system defined along the joint surface. Strain growth in the joint capsules was explained, as related to contact events between the occupant and the seat. A new seat concept was proposed to help lessen the loading level to the neck soft tissues. The foam material of the seat back was softened, the initial gap behind the head was reduced and the head restraint was stiffened for firm support. The lower seat back frame was also reinforced to withstand the impact severity at the given delta-V. Another rear impact simulation was conducted using the new seat concept model to examine the effectiveness of the new concept. The joint capsule strain was found to be relatively lower with the new seat concept. The study also discusses the influence of seat parameters to the vertebral motion and the resultant strain in the joint

  6. Pressure vessel flex joint

    NASA Technical Reports Server (NTRS)

    Kahn, Jon B. (Inventor)

    1992-01-01

    An airtight, flexible joint is disclosed for the interfacing of two pressure vessels such as between the Space Station docking tunnel and the Space Shuttle Orbiter bulkhead adapter. The joint provides for flexibility while still retaining a structural link between the two vessels required due to the loading created by the internal/external pressure differential. The joint design provides for limiting the axial load carried across the joint to a specific value, a function returned in the Orbiter/Station tunnel interface. The flex joint comprises a floating structural segment which is permanently attached to one of the pressure vessels through the use of an inflatable seal. The geometric configuration of the joint causes the tension between the vessels created by the internal gas pressure to compress the inflatable seal. The inflation pressure of the seal is kept at a value above the internal/external pressure differential of the vessels in order to maintain a controlled distance between the floating segment and pressure vessel. The inflatable seal consists of either a hollow torus-shaped flexible bladder or two rolling convoluted diaphragm seals which may be reinforced by a system of straps or fabric anchored to the hard structures. The joint acts as a flexible link to allow both angular motion and lateral displacement while it still contains the internal pressure and holds the axial tension between the vessels.

  7. Spontaneous septic arthritis of the lumbar facet caused by methicillin-resistant Staphylococcus aureus in an otherwise healthy adolescent.

    PubMed

    Papaliodis, Dean N; Roberts, Timothy T; Richardson, Nicholas G; Lawrence, James B

    2014-07-01

    We report the case of a 16-year-old boy with isolated septic arthritis of a lumbar facet. This rare presentation of an infection in a lumbar facet joint occurred after minor trauma sustained in a football game. Septic arthritis of the spinal facet joint is an uncommon phenomenon. Only 5 cases have been reported in immunocompromised pediatric patients. To our knowledge, no case of septic arthritis in an immunocompetent pediatric patient has been reported. An otherwise healthy 16-year-old boy presented with 4 weeks of escalating back pain after a minor athletics-related trauma. Evaluation showed incapacitating pain, lumbar musculature spasms, and the absence of fever, hemodynamic, or neurologic changes. Laboratory values were within normal limits. Magnetic resonance images showed a fluid collection within the L3-L4 facet and a localized abscess. Computed tomographic-guided aspiration showed methicillin-resistant Staphylococcus aureus infection, for which the patient received 6 weeks of vancomycin with complete resolution of symptoms. Refractory lumbago in an adolescent requires careful evaluation. PMID:25046186

  8. Preliminary design of large reflectors with flat facets

    NASA Technical Reports Server (NTRS)

    Agrawal, P. K.; Anderson, M. S.; Card, M. F.

    1980-01-01

    A concept for approximating curved antenna surfaces using flat facets is discussed. A preliminary design technique for determining the size of the reflector surface facets necessary to meet antenna surface accuracy requirements is presented. A proposed large Microwave Radiometer Satellite is selected as an application, and the far field electromagnetic response of a faceted reflector surface is compared with that from a spherical reflector surface.

  9. Preliminary design of large reflectors with flat facets

    NASA Technical Reports Server (NTRS)

    Agrawal, P. K.; Anderson, M. S.; Card, M. F.

    1981-01-01

    A concept for approximating curved antenna surfaces using flat facets is discussed. A preliminary design technique for determining the size of the reflector surface facets necessary to meet antenna surface accuracy requirements is presented. A proposed large microwave radiometer satellite (MRS) is selected as an application, and the far-field electromagnetic response of a faceted reflector surface is compared with that from a spherical reflector surface.

  10. Transverse effects in plasma wakefield acceleration at FACET - Simulation studies

    SciTech Connect

    Adli, E.; Hogan, M.; Frederico, J.; Litos, M. D.; An, W.; Mori, W.

    2012-12-21

    We investigate transverse effects in the plasma-wakefield acceleration experiments planned and ongoing at FACET. We use PIC simulation tools, mainly QuickPIC, to simulate the interaction of the drive electron beam and the plasma. In FACET a number of beam dynamics knobs, including dispersion and bunch length knobs, can be used to vary the beam transverse characteristics in the plasma. We present simulation results and the status of the FACET experimental searches.

  11. Faceted ceramic fibers, tapes or ribbons and epitaxial devices therefrom

    SciTech Connect

    Goyal, Amit

    2013-07-09

    A crystalline article includes a single-crystal ceramic fiber, tape or ribbon. The fiber, tape or ribbon has at least one crystallographic facet along its length, which is generally at least one meter long. In the case of sapphire, the facets are R-plane, M-plane, C-plane or A-plane facets. Epitaxial articles, including superconducting articles, can be formed on the fiber, tape or ribbon.

  12. Faceted ceramic fibers, tapes or ribbons and epitaxial devices therefrom

    SciTech Connect

    Goyal, Amit

    2012-07-24

    A crystalline article includes a single-crystal ceramic fiber, tape or ribbon. The fiber, tape or ribbon has at least one crystallographic facet along its length, which is generally at least one meter long. In the case of sapphire, the facets are R-plane, M-plane, C-plane or A-plane facets. Epitaxial articles, including superconducting articles, can be formed on the fiber, tape or ribbon.

  13. [Performance assessment using the Many-Facet Rasch Measurement].

    PubMed

    Prieto Adánez, Gerardo

    2011-04-01

    This paper describes how the Many-Facet Rasch Measurement (MFRM) can be applied to constructed-response items and rater analysis. The article provides an introduction to MFRM, a description of facet analysis procedures, and an illustrative example to examine the effects of various sources of variability on students' performance on a DELE (Diplomas in Spanish as a Foreign Language) test by means of the FACETS program. Results highlight the usefulness of the MFRM to detect raters that have extreme values on the continuum of severity. MFRM facilitates comprehension of the assessment process as well as providing objective measurement of facet elements. PMID:21504675

  14. Faceted Gold Nanorods: Nanocuboids, Convex Nanocuboids, and Concave Nanocuboids.

    PubMed

    Zhang, Qingfeng; Zhou, Yadong; Villarreal, Esteban; Lin, Ye; Zou, Shengli; Wang, Hui

    2015-06-10

    Au nanorods are optically tunable anisotropic nanoparticles with built-in catalytic activities. The state-of-the-art seed-mediated nanorod synthesis offers excellent control over the aspect ratios of cylindrical Au nanorods, which enables fine-tuning of plasmon resonances over a broad spectral range. However, facet control of Au nanorods with atomic-level precision remains significantly more challenging. The coexistence of various types of low-index and high-index facets on the highly curved nanorod surfaces makes it extremely challenging to quantitatively elucidate the atomic-level structure-property relationships that underpin the catalytic competence of Au nanorods. Here we demonstrate that cylindrical Au nanorods undergo controlled facet evolution during their overgrowth in the presence of Cu(2+) and cationic surfactants, resulting in the formation of anisotropic nanostructures enclosed by well-defined facets, such as low-index faceting nanocuboids and high-index faceting convex nanocuboids and concave nanocuboids. These faceted Au nanorods exhibit enriched optical extinction spectral features, broader plasmonic tuning range, and enhanced catalytic tunability in comparison to the conventional cylindrical Au nanorods. The capabilities to both fine-tailor the facets and fine-tune the plasmon resonances of anisotropic Au nanoparticles open up unique opportunities for us to study, in great detail, the facet-dependent interfacial molecular transformations on Au nanocatalysts using surface-enhanced Raman scattering as a time-resolved spectroscopic tool. PMID:25927399

  15. Optimized bolted joint

    NASA Technical Reports Server (NTRS)

    Hart-Smith, L. J.; Bunin, B. L.; Watts, D. J. (Inventor)

    1986-01-01

    A method is disclosed for joining segments of the skin of an aircraft. The ends of the skin are positioned in close proximity or abutt each other. The skin is of constant thickness throughout the joint and is sandwiched between splice plates, which taper in thickness from the last to the first bolt rows in order to reduce the stiffness of the splice plate and thereby reduce the load transfer at the location where bypass loads are the highest.

  16. Dysplasia of the caudal vertebral articular facets in four dogs: results of radiographic, myelographic and magnetic resonance imaging investigations.

    PubMed

    Penderis, J; Schwarz, T; McConnell, J F; Garosi, L S; Thomson, C E; Dennis, R

    2005-05-01

    Congenital anomalies of the vertebral column associated with aberrations of one of the primary vertebral ossification centres have been frequently described in the veterinary literature, but clinically significant abnormalities of secondary vertebral ossification centres, particularly involving the caudal articular processes, are much less frequently reported. This paper describes three dogs with aplasia and one dog with hypoplasia of the caudal vertebral articular processes. Thoracolumbar spinal cord compression and ataxia was evident in the three dogs with aplasia but no clinical signs were evident in the dog with hypoplasia. The radiographic appearance was similar in all four cases, with aplasia or hypoplasia of the caudal articular facets at one or more intervertebral joints in the thoracolumbar region. Bone proliferation was evident secondary to an associated degenerative joint disease. Compensatory hyperplasia of the adjacent cranial articular facets and ligamentum flavum protruded into the vertebral canal, resulting in a compressive myelopathy observed by myelography and magnetic resonance imaging. PMID:15879540

  17. Within-Trait Heterogeneity in Age Group Differences in Personality Domains and Facets: Implications for the Development and Coherence of Personality Traits

    PubMed Central

    Mõttus, René; Realo, Anu; Allik, Jüri; Esko, Tõnu; Metspalu, Andres; Johnson, Wendy

    2015-01-01

    The study investigated differences in the Five-Factor Model (FFM) domains and facets across adulthood. The main questions were whether personality scales reflected coherent units of trait development and thereby coherent personality traits more generally. These questions were addressed by testing if the components of the trait scales (items for facet scales and facets for domain scales) showed consistent age group differences. For this, measurement invariance (MI) framework was used. In a sample of 2,711 Estonians who had completed the NEO Personality Inventory 3 (NEO PI-3), more than half of the facet scales and one domain scale did not meet the criterion for weak MI (factor loading equality) across 12 age groups spanning ages from 18 to 91 years. Furthermore, none of the facet and domain scales met the criterion for strong MI (intercept equality), suggesting that items of the same facets and facets of the same domains varied in age group differences. When items were residualized for their respective facets, 46% of them had significant (p < 0.0002) residual age-correlations. When facets were residualized for their domain scores, a majority had significant (p < 0.002) residual age-correlations. For each domain, a series of latent factors were specified using random quarters of their items: scores of such latent factors varied notably (within domains) in correlations with age. We argue that manifestations of aetiologically coherent traits should show similar age group differences. Given this, the FFM domains and facets as embodied in the NEO PI-3 do not reflect aetiologically coherent traits. PMID:25751273

  18. Determination of Parachute Joint Factors using Seam and Joint Testing

    NASA Technical Reports Server (NTRS)

    Mollmann, Catherine

    2015-01-01

    This paper details the methodology for determining the joint factor for all parachute components. This method has been successfully implemented on the Capsule Parachute Assembly System (CPAS) for the NASA Orion crew module for use in determining the margin of safety for each component under peak loads. Also discussed are concepts behind the joint factor and what drives the loss of material strength at joints. The joint factor is defined as a "loss in joint strength...relative to the basic material strength" that occurs when "textiles are connected to each other or to metals." During the CPAS engineering development phase, a conservative joint factor of 0.80 was assumed for each parachute component. In order to refine this factor and eliminate excess conservatism, a seam and joint testing program was implemented as part of the structural validation. This method split each of the parachute structural joints into discrete tensile tests designed to duplicate the loading of each joint. Breaking strength data collected from destructive pull testing was then used to calculate the joint factor in the form of an efficiency. Joint efficiency is the percentage of the base material strength that remains after degradation due to sewing or interaction with other components; it is used interchangeably with joint factor in this paper. Parachute materials vary in type-mainly cord, tape, webbing, and cloth -which require different test fixtures and joint sample construction methods. This paper defines guidelines for designing and testing samples based on materials and test goals. Using the test methodology and analysis approach detailed in this paper, the minimum joint factor for each parachute component can be formulated. The joint factors can then be used to calculate the design factor and margin of safety for that component, a critical part of the design verification process.

  19. FACET Tolerances for Static and Dynamic Misalignments

    SciTech Connect

    Federico, Joel

    2012-07-13

    The Facility for AdvancedAccelerator and Experimental Tests (FACET) at the SLAC National Accelerator Laboratory is designed to deliver a beam with a transverse spot size on the order of 10 {micro}m x 10 {micro}m in a new beamline constructed at the two kilometer point of the SLAC linac. Commissioning the beamline requires mitigating alignment errors and their effects, which can be significant and result in spot sizes orders of magnitude larger. Sextupole and quadrupole alignment errors in particular can introduce errors in focusing, steering, and dispersion which can result in spot size growth, beta mismatch, and waist movement. Alignment errors due to static misalignments, mechanical jitter, energy jitter, and other physical processes can be analyzed to determine the level of accuracy and precision that the beamline requires. It is important to recognize these effects and their tolerances in order to deliver a beam as designed.

  20. Psychopathy and instrumental violence: facet level relationships.

    PubMed

    Walsh, Zach; Swogger, Marc T; Kosson, David S

    2009-08-01

    The relationship between psychopathy and violence is well established. However, the extent to which psychopathy is related to different types of violent behavior warrants further study. We examined the relationship between instrumental violence, psychopathy, and psychopathic traits among 248 European American and African American adult male county jail inmates. We assessed instrumentality based on subjective motivations for respondent-identified acts of violence. Psychopathy was assessed using the PCL-R based on interview and file review. We controlled for potentially important covariates, namely IQ and prior violence. Results were in part consistent with findings from studies with adolescents, in that we identified a positive relationship between instrumentality of violence and manipulative interpersonal style. Results differed from youth studies with regard to relationships between instrumentality and other facets of psychopathy. The implications of our study are discussed with regard to treatment and the developmental stability of the relationship between psychopathic traits and instrumental violence. PMID:19663661

  1. Detecting the Multiple Facets of Biodiversity.

    PubMed

    Jarzyna, Marta A; Jetz, Walter

    2016-07-01

    Interest in, and opportunities to include functional and phylogenetic attributes of species in community ecology and biogeography are rapidly growing and seen as vital for the assessment of status and trends in biodiversity. However, the fundamental underlying evidence remains the (co-)occurrence of the biological units, such as species, in time and space and our ability to appropriately detect and quantify them. Here, we examine the implications of imperfect detection of species for functional and phylogenetic diversity (FD and PD) estimates. We explore how FD and PD might have different detectabilities than taxonomic diversity (TD) and how all three might vary differently along spatial and environmental gradients. We also extend occupancy modeling and dendrogram-based methods to address the imperfect detection of different biodiversity facets. PMID:27168115

  2. Diagnostics Challenges for FACET-II

    SciTech Connect

    Clarke, Christine

    2015-10-07

    FACET-II is a prospective user facility at SLAC National Accelerator Laboratory. The facility will focus on high-energy, high-brightness beams and their interaction with plasma and lasers. The accelerator is designed for high-energy-density electron beams with peak currents of approximately 50 kA (potentially 100 kA) that are focused down to below 10x10 micron transverse spot size at an energy of 10 GeV. Subsequent phases of the facility will provide positron beams above 10 kA peak current to the experiment station. Experiments will require well characterised beams; however, the high peak current of the electron beam can lead to material failure in wirescanners, optical transition radiation screens and other instruments critical for measurement or delivery. The radiation environment and space constraints also put additional pressure on diagnostic design.

  3. Finite element modeling of the cervical spine: role of intervertebral disc under axial and eccentric loads.

    PubMed

    Kumaresan, S; Yoganandan, N; Pintar, F A; Maiman, D J

    1999-12-01

    An anatomically accurate, three-dimensional, nonlinear finite element model of the human cervical spine was developed using computed tomography images and cryomicrotome sections. The detailed model included the cortical bone, cancellous core, endplate, lamina, pedicle, transverse processes and spinous processes of the vertebrae; the annulus fibrosus and nucleus pulposus of the intervertebral discs; the uncovertebral joints; the articular cartilage, the synovial fluid and synovial membrane of the facet joints; and the anterior and posterior longitudinal ligaments, interspinous ligaments, capsular ligaments and ligamentum flavum. The finite element model was validated with experimental results: force-displacement and localized strain responses of the vertebral body and lateral masses under pure compression, and varying eccentric anterior-compression and posterior-compression loading modes. This experimentally validated finite element model was used to study the biomechanics of the cervical spine intervertebral disc by quantifying the internal axial and shear forces resisted by the ventral, middle, and dorsal regions of the disc under the above axial and eccentric loading modes. Results indicated that higher axial forces (compared to shear forces) were transmitted through different regions of the disc under all loading modes. While the ventral region of the disc resisted higher variations in axial force, the dorsal region transmitted higher shear forces under all loading modes. These findings may offer an insight to better understand the biomechanical role of the human cervical spine intervertebral disc. PMID:10717549

  4. Ball-joint grounding ring

    NASA Technical Reports Server (NTRS)

    Aperlo, P. J. A.; Buck, P. A.; Weldon, V. A.

    1981-01-01

    In ball and socket joint where electrical insulator such as polytetrafluoroethylene is used as line to minimize friction, good electrical contact across joint may be needed for lightning protection or to prevent static-charge build-up. Electrical contact is maintained by ring of spring-loaded fingers mounted in socket. It may be useful in industry for cranes, trailers, and other applications requiring ball and socket joint.

  5. The Construct of Agreeableness: Facet vs. Item Level Analysis

    ERIC Educational Resources Information Center

    Newgent, Rebecca A.; Lee, Sang Min; Higgins, Kristin K.; Mulvenon, Sean W.; Connors, Joanie V.

    2004-01-01

    The Revised NEO Personality Inventory (NEO PI-R) was developed to operationalize the Five-Factor Model of Personality. Using correlational analysis and confirmatory and exploratory factor analysis, the present study investigates the facet structure of the domain of Agreeableness of the NEO-PI-R at the facet and item level to assess which is a more…

  6. Oxygen induced facet formation on Rh(2 1 0) surface

    NASA Astrophysics Data System (ADS)

    Govind; Chen, Wenhua; Wang, Hao; Madey, T. E.

    2009-10-01

    Oxygen induced nanometer-scale faceting of the atomically rough Rh(2 1 0) surface has been studied using Auger electron spectroscopy (AES), low energy electron diffraction (LEED), and scanning tunneling microscopy (STM). The Rh(2 1 0) surface completely covered with nanometer-scale facets when annealed at ≥550 K in the presence of oxygen. LEED studies reveal that the pyramidal faceted surface is characterized by three-sided nanoscale pyramids exposing (7 3 1), (7 3 -1) and (1 1 0) faces. A clean faceted surface was prepared through the use of low temperature surface cleaning method using the reaction with H 2 while preserving ("freezing") the pyramidal facet structure. The resulting clean faceted surface remains stable for T ˜ 600 K and for higher temperatures; the faceted surface irreversibly relaxes to the planar surface. STM measurements confirms the formation of nanopyramids with average pyramid size ranging from 12 to 21 nm depending upon the annealing temperature. The nanopyramidal faceted Rh surface may be used as a potential template for the growth of metallic nanoclusters and for structure sensitive reactions.

  7. Domains and Facets: A Hierarchical Approach to Personality Assessment.

    ERIC Educational Resources Information Center

    McCrae, Robert R.

    The domain and facet approach to personality assessment is discussed. The strategy used to identify and measure aspects of the five factors of personality structure is described. Evidence concerning the factorial invariance of the resulting set of 30 facet scales and some recent evidence concerning their discriminant validity are reviewed. Some…

  8. Search Interface Design Using Faceted Indexing for Web Resources.

    ERIC Educational Resources Information Center

    Devadason, Francis; Intaraksa, Neelawat; Patamawongjariya, Pornprapa; Desai, Kavita

    2001-01-01

    Describes an experimental system designed to organize and provide access to Web documents using a faceted pre-coordinate indexing system based on the Deep Structure Indexing System (DSIS) derived from POPSI (Postulate based Permuted Subject Indexing) of Bhattacharyya, and the facet analysis and chain indexing system of Ranganathan. (AEF)

  9. Mamillo-accessory notch and foramen: distribution patterns and correlation with superior lumbar facet structure.

    PubMed

    Mahato, N K

    2014-12-01

    The mamillary (MP) and the accessory (AP) processes are two important anatomical landmarks in the lumbar vertebral morphology. These two processes form the mamillo-accessory notch (MAN) between them. In the living, the MP and the AP are connected together by the mamillo-accessory ligament (MAL). The medial branches of lumbar dorsal rami pass underneath the MAL. The MAL often undergoes varied degrees of ossification with diverse notching at the junction of these two processes, often with formation of a discrete foramen (MAF). Reports on the distribution of these notches (MAN) and foramina (MAF) are very few and most of them do not discuss such ossification in context of morphology of adjoining structures in the vertebrae. Lumbar vertebral and sacral specimens were screened for three different categories of narrowing at the mamillo-accessory junction: firstly >1/2 notch, secondly ¾ notch, and thirdly MAF and their distribution patterns were mapped along the lumbar spine. Transverse dimensions of superior facet articulating surfaces [length (a)] and widths of MPs [length (b)] were recorded. Relative widths of the MPs were calculated as index M (a/b). Results suggest associations between the degrees of assimilation of the MPs into the facet joints, the index M values, and the different types of mamillo-accessory junctional anatomy. This study may help to understand if MAN and MAF related dorsal rami entrapment neuropathies arise merely due to osteoarthritic ossification of the MAL or could also be accounted for by facet dimensions or degree of MP-facet fusions that abut close to the mamillo-accessory junctions. PMID:24889272

  10. Efficacy of a trunk orthosis with joints providing resistive force on low-back load in elderly persons during static standing

    PubMed Central

    Katsuhira, Junji; Matsudaira, Ko; Yasui, Tadashi; Iijima, Shinno; Ito, Akihiro

    2015-01-01

    Purpose Postural alignment of elderly people becomes poor due to aging, possibly leading to low-back pain and spinal deformity. Although there are several interventions for treating these conditions, no previous study has reported the effectiveness of a spinal orthosis or lumbosacral orthosis (LSO) in healthy elderly people without specific spinal deformity. We therefore developed a trunk orthosis to decrease low-back muscle activity while training good postural alignment through resistive force provided by joints with springs (here, called the ORF, which stands for orthosis with joints providing resistive force) as a preventive method against abnormal posture and low-back pain in healthy elderly persons. Patients and methods Fifteen community-dwelling elderly men participated in this study. Participants stood freely for 10 seconds in a laboratory setting under three conditions: without an orthosis, with the ORF, and with an LSO. The Damen corset LSO was selected as it is frequently prescribed for patients with low-back pain. Postural alignment during static standing was recorded using a three-dimensional motion capture system employing infrared cameras. Two force plates were used to record center of pressure. Electromyograms were obtained for bilateral erector spinae (ES), left internal abdominal oblique, and right gluteus medius muscles. Results Pelvis forward tilt angle tended to increase while wearing the ORF and decrease while wearing the LSO, but these results were not significant compared to no orthosis. Thorax extension angle and thorax angle on pelvis coordinate system significantly increased while wearing the ORF compared to the other two conditions. ES activity significantly decreased while wearing the ORF compared to the other two conditions. Internal oblique activity was significantly smaller while wearing the LSO than with no orthosis. Center of pressure did not significantly differ among the conditions. Conclusion The ORF significantly improved trunk

  11. Automated design of a uniform distribution using faceted reflectors

    NASA Astrophysics Data System (ADS)

    Cassarly, William J.; David, Stuart R.; Jenkins, David G.; Riser, Andrew; Davenport, Thomas L.

    2000-07-01

    Faceted reflectors are a ubiquitous means for providing uniform illumination in many commercial lighting products, examples being newer flashlights, department-store display lighting, and the faceted reflectors found in overhead projectors. However, the design of faceted reflectors using software has often been more limited by the tools available to design them than by the imagination of the designers. One of the keys to enabling a broader range of design options has been to allow more complex surfaces using constructive solid geometry (CSG). CSG uses Boolean operations on basic geometric primitives to define shapes to create individual facets. In this paper, we describe an improved faceted reflector design algorithm and use it to create a wide range of CSG-based reflectors. The performance of various reflectors is compared using a Monte Carlo ray-trace method.

  12. Hypermobile joints

    MedlinePlus

    ... too far. In children with hypermobility syndrome, those ligaments are loose or weak. This may lead to: Arthritis, which may develop over time Dislocated joints, which is a separation of two bones where they meet at a joint Sprains and strains Children with hypermobile joints also often have flat ...

  13. Joint Disorders

    MedlinePlus

    A joint is where two or more bones come together, like the knee, hip, elbow, or shoulder. Joints can be damaged by many types of injuries or diseases, including Arthritis - inflammation of a joint. It causes pain, stiffness, and swelling. Over time, ...

  14. Cervical facet dislocation adjacent to the fused motion segment

    PubMed Central

    Yokoyama, Kunio; Kawanishi, Masahiro; Yamada, Makoto; Tanaka, Hidekazu; Ito, Yutaka; Kuroiwa, Toshihiko

    2016-01-01

    This study reports on a case that forces re-examination of merits and demerits of anterior cervical fusion. A 79-year-old male was brought to the emergency room (ER) of our hospital after he fell and struck the occipital region of his head following excessive alcohol consumption. Four years prior, he had undergone anterior cervical discectomy and fusion of C5/6 and a magnetic resonance imaging (MRI) performed 3 years after this surgery indicated that he was suffering from degeneration of C6/7 intervertebral discs. After arriving at the ER, he presented motor impairment at level C7 and lower of manual muscle testing grade 1 as well as moderate loss of physical sensation from the trunk and peripheries of both upper limbs to the peripheries of both lower limbs (Frankel B). Cervical computed tomography (CT) indicated anterior dislocation of C6/7, and MRI indicated severe spinal cord edema. We performed manipulative reduction of C6/7 with the patient under general anesthesia. Next, we performed laminectomy on C5-T1 and posterior fusion on C6/7. Postoperative CT indicated that cervical alignment had improved, and MRI indicated that the spinal cord edema observed prior to surgery had been mitigated. Three months after surgery, motor function and sensory impairment of the lower limbs had improved, and the patient was ambulatory upon discharge from the hospital (Frankel D). In the present case, although C5 and 6 were rigidly fused, degeneration of the C6/7 intervertebral disc occurred and stability was compromised. As a result, even slight trauma placed a severe dynamic burden on the facet joint of C6/7, which led to dislocation. PMID:26933361

  15. Cervical facet dislocation adjacent to the fused motion segment.

    PubMed

    Yokoyama, Kunio; Kawanishi, Masahiro; Yamada, Makoto; Tanaka, Hidekazu; Ito, Yutaka; Kuroiwa, Toshihiko

    2016-01-01

    This study reports on a case that forces re-examination of merits and demerits of anterior cervical fusion. A 79-year-old male was brought to the emergency room (ER) of our hospital after he fell and struck the occipital region of his head following excessive alcohol consumption. Four years prior, he had undergone anterior cervical discectomy and fusion of C5/6 and a magnetic resonance imaging (MRI) performed 3 years after this surgery indicated that he was suffering from degeneration of C6/7 intervertebral discs. After arriving at the ER, he presented motor impairment at level C7 and lower of manual muscle testing grade 1 as well as moderate loss of physical sensation from the trunk and peripheries of both upper limbs to the peripheries of both lower limbs (Frankel B). Cervical computed tomography (CT) indicated anterior dislocation of C6/7, and MRI indicated severe spinal cord edema. We performed manipulative reduction of C6/7 with the patient under general anesthesia. Next, we performed laminectomy on C5-T1 and posterior fusion on C6/7. Postoperative CT indicated that cervical alignment had improved, and MRI indicated that the spinal cord edema observed prior to surgery had been mitigated. Three months after surgery, motor function and sensory impairment of the lower limbs had improved, and the patient was ambulatory upon discharge from the hospital (Frankel D). In the present case, although C5 and 6 were rigidly fused, degeneration of the C6/7 intervertebral disc occurred and stability was compromised. As a result, even slight trauma placed a severe dynamic burden on the facet joint of C6/7, which led to dislocation. PMID:26933361

  16. The spreading of a void on a facet during electromigration

    SciTech Connect

    Chu, X.; Bauer, C.L.; Mullins, W.W.; Klinger, L.M.

    1997-07-01

    A void of cross sectional area A may spread perpendicular to the applied electric field E{sub a} during electromigration because its leading surface develops a facet whose advance is limited by the supply of steps. If the facet is immobile (no step source) and the remaining surface is free to move, and if E{sub a}A is less than a threshold value, then the void assumes a stationary elongated shape dictated by a balance between capillarity and electric field. If E{sub a}A exceeds the threshold value, however, a balance is no longer possible, and the void spreads along the facet without arrest. If the facet has limited mobility, a balance is possible for all values of E{sub a}A, resulting in an elongated moving steady-state shape. The treatment simplifies the void shape as rectangular but preserves the essential features of capillarity and surface electromigration. The authors argue that the motion of a facet on a void along the outward normal requires defects (e.g., intersecting screw dislocations) that act as step sources since homogeneous nucleation of steps on the facet is expected to be negligible. Since voids in fine-line interconnects are often observed to be partially faceted, restricted void motion and resultant spreading which depend sensitively on crystallographic features, such as defect structure and grain orientation, may indeed limit the lifetime of fine-line interconnects in electronic devices.

  17. Explorations in statistics: statistical facets of reproducibility.

    PubMed

    Curran-Everett, Douglas

    2016-06-01

    Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This eleventh installment of Explorations in Statistics explores statistical facets of reproducibility. If we obtain an experimental result that is scientifically meaningful and statistically unusual, we would like to know that our result reflects a general biological phenomenon that another researcher could reproduce if (s)he repeated our experiment. But more often than not, we may learn this researcher cannot replicate our result. The National Institutes of Health and the Federation of American Societies for Experimental Biology have created training modules and outlined strategies to help improve the reproducibility of research. These particular approaches are necessary, but they are not sufficient. The principles of hypothesis testing and estimation are inherent to the notion of reproducibility in science. If we want to improve the reproducibility of our research, then we need to rethink how we apply fundamental concepts of statistics to our science. PMID:27231259

  18. Distal radioulnar joint injuries.

    PubMed

    Thomas, Binu P; Sreekanth, Raveendran

    2012-09-01

    Distal radioulnar joint is a trochoid joint relatively new in evolution. Along with proximal radioulnar joint, forearm bones and interosseous membrane, it allows pronosupination and load transmission across the wrist. Injuries around distal radioulnar joint are not uncommon, and are usually associated with distal radius fractures,fractures of the ulnar styloid and with the eponymous Galeazzi or Essex_Lopresti fractures. The injury can be purely involving the soft tissue especially the triangular fibrocartilage or the radioulnar ligaments. The patients usually present with ulnar sided wrist pain, features of instability, or restriction of rotation. Difficulty in carrying loads in the hand is a major constraint for these patients. Thorough clinical examination to localize point of tenderness and appropriate provocative tests help in diagnosis. Radiology and MRI are extremely useful, while arthroscopy is the gold standard for evaluation. The treatment protocols are continuously evolving and range from conservative, arthroscopic to open surgical methods. Isolated dislocation are uncommon. Basal fractures of the ulnar styloid tend to make the joint unstable and may require operative intervention. Chronic instability requires reconstruction of the stabilizing ligaments to avoid onset of arthritis. Prosthetic replacement in arthritis is gaining acceptance in the management of arthritis. PMID:23162140

  19. Characterization of etched facets for GaN-based lasers

    NASA Astrophysics Data System (ADS)

    Scherer, M.; Schwegler, V.; Seyboth, M.; Eberhard, F.; Kirchner, C.; Kamp, M.; Ulu, G.; Ünlü, M. S.; Gruhler, R.; Hollricher, O.

    2001-09-01

    Dry-etching of laser facets is commonly used for (InAl)GaN/sapphire-based structures since the epitaxial planes of the nitride layers are rotated with respect to the substrate planes making cleaving impractical. To achieve steep and smooth facets by chemically assisted ion beam etching, a 3-layer resist system is developed for patterning. Characterization by scanning electron microscopy and atomic force microscopy shows facets with root-mean-square roughnesses of 7 nm and inclination angles of 2-4°. Optically pumped lasers yield low threshold excitation densities for fully doped separate confinement heterostructure lasers.

  20. Morphological evolution in oxygen-induced faceting of Re(1231)

    SciTech Connect

    Wang Hao; Chen Wenhua; Madey, Theodore E.

    2006-11-15

    We have studied oxygen-induced faceting of the atomically rough Re(1231) surface by means of Auger electron spectroscopy, low energy electron diffraction, and scanning tunneling microscopy (STM). In contrast to previous faceting studies on other refractory metal surfaces, where simple morphologies of the facets were reported, we find a coverage-dependent morphological evolution of the facets ranging from long sawtooth ridges to complex structures exposing four different facets. The faceting occurs only when oxygen coverage ({theta}) exceeds 0.5 monolayer (ML) and the surface is annealed at {>=}700 K. At low oxygen coverage (0.5 ML{<=}{theta}<0.7 ML), the O/Re(1231) surface becomes partially faceted upon annealing; further increasing of oxygen coverage (0.7 ML{<=}{theta}<0.9 ML) causes the surface to become completely faceted, forming long sawtooth ridges along the [2113] direction with typical dimensions of {approx}8 nm in width and >50 nm in length upon annealing at 1000 K. The size of the ridges grows with annealing temperature and annealing time, and the distance between the ridges is quite uniform. The two sides of each ridge have (0110) and (1121) orientations, and atomic-resolution STM images reveal that the edge of the ridge is atomically sharp. For 0.9 ML{<=}{theta}<1 ML, a third set of facets, identified as (1010), emerges and truncates the original ridges. With the surface fully covered by oxygen ({theta}=1 ML), a fourth facet (0111) also becomes prominent upon annealing. This morphological evolution is accompanied by a reduction of the average ridge length along [2113], indicating that the (1121) facet is metastable. Our work demonstrates that even in a simple adsorbate/substrate system, the adsorbate-induced modification of the anisotropy of surface free energy can induce a complex sequence of changes in the surface morphology. The faceted Re surfaces may be model systems to study structure sensitivity in catalytic reactions, and may also provide

  1. High pressure ceramic joint

    DOEpatents

    Ward, M.E.; Harkins, B.D.

    1993-11-30

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures. 4 figures.

  2. High pressure ceramic joint

    DOEpatents

    Ward, Michael E.; Harkins, Bruce D.

    1993-01-01

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

  3. Specifying Valid Compound Terms in Interrelated Faceted Taxonomies

    NASA Astrophysics Data System (ADS)

    Analyti, Anastasia; Tzitzikas, Yannis; Spyratos, Nicolas

    In previous work, we proposed an algebra whose operators allow to specify the valid compound terms of a faceted taxonomy, in a flexible manner (by combining positive and negative statements). In this paper, we treat the same problem but in a more general setting, where the facet taxonomies are not independent but are (possibly) interrelated through narrower/broader relationships between their terms. The proposed algebra, called Interrelated Facet Composition Algebra (IFCA), is more powerful, as the valid compound terms of a faceted taxonomy can be derived through a smaller set of declared valid and/or invalid compound terms. An optimized (w.r.t. the naive approach) algorithm that checks compound term validity, according to a well-formed IFCA expression, and its worst-time complexity are provided.

  4. Hydrothermal growth of multi-facet anatase spheres

    NASA Astrophysics Data System (ADS)

    Wu, Jin-Ming; Song, Xiao-Mei; Ma, Lu-Yao; Wei, Xiao-Dan

    2011-03-01

    Titania with various nanostructures can be synthesized by several F --mediated procedures. In this paper, we report the synthesis of a novel multi-facet microsphere consisting of etched single-crystalline anatase by simply immersing metallic Ti plates in an HF aqueous solution under hydrothermal conditions. The etched multi-facet sphere was found to grow through the nucleation and growth of truncated bipyramids on a previously precipitated one to assemble a microsphere, and its subsequent etching by HF to expose the thermodynamic stable {1 0 1} facets. The photocatalytic activity of such etched multi-facet sphere thin films was evaluated utilizing rhodamine B and sulfonic salicylic acid in water as target molecules and compared with commercial Degussa P25 titania nanoparticles.

  5. Correlation between crystallographic orientation and surface faceting in UO2

    NASA Astrophysics Data System (ADS)

    Miao, Yinbin; Mo, Kun; Yao, Tiankai; Lian, Jie; Fortner, Jeffrey; Jamison, Laura; Xu, Ruqing; Yacout, Abdellatif M.

    2016-09-01

    Here coordinated experimental efforts to quantitatively correlate crystallographic orientation and surface faceting features in UO2 are reported upon. A sintered polycrystalline UO2 sample was thermally etched to induce the formation of surface faceting features. Synchrotron Laue microdiffraction was used to obtain a precise crystallographic orientation map for the UO2 surface grains. Scanning electron microscopy (SEM) was utilized to collect the detailed information on the surface morphology of the sample. The surface faceting features were found to be highly dependent on the crystallographic orientation. In most cases, Triple-plane structures containing one {100} plane and two {111} planes were found to dominate the surface of UO2. The orientation-faceting relationship established in this study revealed a practical and efficient method of determining crystallographic orientation based on the surface features captured by SEM images.

  6. Faceted metal and metal oxide nanoparticles: design, fabrication and catalysis.

    PubMed

    Pal, Jaya; Pal, Tarasankar

    2015-09-14

    The review addresses new advances in metal, bimetallic, metal oxide, and composite particles in their nanoregime for facet-selective catalytic applications. The synthesis and growth mechanisms of the particles have been summarized in brief in this review with a view to develop critical examination of the faceted morphology of the particles for catalysis. The size, shape and composition of the particles have been found to be largely irrelevant in comparison to the nature of facets in catalysis. Thus selective high- and low-index facets have been found to selectively promote adsorption, which eventually leads to an effective catalytic reaction. As a consequence, a high density of atoms rest at the corners, steps, stages, kinks etc on the catalyst surface in order to host the adsorbate efficiently and catalyze the reaction. Again, surface atomic arrangement and bond length have been found to play a dominant role in adsorption, leading to effective catalysis. PMID:26255749

  7. Faceted metal and metal oxide nanoparticles: design, fabrication and catalysis

    NASA Astrophysics Data System (ADS)

    Pal, Jaya; Pal, Tarasankar

    2015-08-01

    The review addresses new advances in metal, bimetallic, metal oxide, and composite particles in their nanoregime for facet-selective catalytic applications. The synthesis and growth mechanisms of the particles have been summarized in brief in this review with a view to develop critical examination of the faceted morphology of the particles for catalysis. The size, shape and composition of the particles have been found to be largely irrelevant in comparison to the nature of facets in catalysis. Thus selective high- and low-index facets have been found to selectively promote adsorption, which eventually leads to an effective catalytic reaction. As a consequence, a high density of atoms rest at the corners, steps, stages, kinks etc on the catalyst surface in order to host the adsorbate efficiently and catalyze the reaction. Again, surface atomic arrangement and bond length have been found to play a dominant role in adsorption, leading to effective catalysis.

  8. Local and social facets of planetary boundaries: right to nutrients

    NASA Astrophysics Data System (ADS)

    Kahiluoto, Helena; Kuisma, Miia; Kuokkanen, Anna; Mikkilä, Mirja; Linnanen, Lassi

    2015-10-01

    Anthropogenic nutrient flows exceed the planetary boundaries. The boundaries and the current excesses vary spatially. Such variations have both an ecological and a social facet. We explored the spatial variation using a bottom-up approach. The local critical boundaries were determined through the current or accumulated flow of the preceding five years before the planetary boundary criteria were met. Finland and Ethiopia served as cases with contrasting ecology and wealth. The variation in excess depends on historical global inequities in the access to nutrients. Globally, the accumulated use per capita is 2300 kg reactive nitrogen (Nr) and 200 kg phosphorus (P). For Finland, the accumulated use per capita is 3400 kg Nr and 690 kg P, whereas for Ethiopia, it is 26 kg Nr and 12 kg P. The critical N boundary in Finland is currently exceeded by 40 kg cap-1 a-1 and the accumulated excess is 65 kg cap-1 a-1, while the global current excess is 24 kg cap-1 a-1 and there is space in Ethiopia to increase even the accumulated flow. The critical P boundary is exceeded in Finland and (although less so) in Ethiopia, but for contrary reasons: (1) the excessive past inflow to the agrifood system in Finland and (2) the excessive outflow from the agrifood system triggered by deficits in inflow and waste management in Ethiopia. The critical boundaries set by Finnish marine systems are lower and those set by freshwaters are higher than the planetary boundaries downscaled per capita. The shift to dominance of internal loading in watercourses represents a tipping point. We conclude that food security within the safe boundaries requires global redistribution of nutrients in residues, soils and sediments and of rights to use nutrients. Bottom-up assessments reveal local dynamics that shed new light on the relevant boundary criteria and on estimates and remedies.

  9. Analysis on linac quadrupole misalignment in FACET commissioning 2012

    SciTech Connect

    Sun, Yipeng; /SLAC

    2012-07-05

    In this note, the analysis on linac quadrupole misalignment is presented for the FACET linac section LI05-09 plus LI11-19. The effectiveness of the beam-based alignment technique is preliminarily confirmed by the measurement. Beam-based alignment technique was adopted at SLAC linac since SLC time. Here the beam-based alignment algorithms are further developed and applied in the FACET commissioning during 2012 run.

  10. Framework Application for Core Edge Transport Simulation (FACETS)

    SciTech Connect

    Malony, Allen D; Shende, Sameer S; Huck, Kevin A; Mr. Alan Morris, and Mr. Wyatt Spear

    2012-03-14

    The goal of the FACETS project (Framework Application for Core-Edge Transport Simulations) was to provide a multiphysics, parallel framework application (FACETS) that will enable whole-device modeling for the U.S. fusion program, to provide the modeling infrastructure needed for ITER, the next step fusion confinement device. Through use of modern computational methods, including component technology and object oriented design, FACETS is able to switch from one model to another for a given aspect of the physics in a flexible manner. This enables use of simplified models for rapid turnaround or high-fidelity models that can take advantage of the largest supercomputer hardware. FACETS does so in a heterogeneous parallel context, where different parts of the application execute in parallel by utilizing task farming, domain decomposition, and/or pipelining as needed and applicable. ParaTools, Inc. was tasked with supporting the performance analysis and tuning of the FACETS components and framework in order to achieve the parallel scaling goals of the project. The TAU Performance System® was used for instrumentation, measurement, archiving, and profile / tracing analysis. ParaTools, Inc. also assisted in FACETS performance engineering efforts. Through the use of the TAU Performance System, ParaTools provided instrumentation, measurement, analysis and archival support for the FACETS project. Performance optimization of key components has yielded significant performance speedups. TAU was integrated into the FACETS build for both the full coupled application and the UEDGE component. The performance database provided archival storage of the performance regression testing data generated by the project, and helped to track improvements in the software development.

  11. Effects of Intensive Diet and Exercise on Knee Joint Loads, Inflammation, and Clinical Outcomes Among Overweight and Obese Adults With Knee Osteoarthritis

    PubMed Central

    Messier, Stephen P.; Mihalko, Shannon L.; Legault, Claudine; Miller, Gary D.; Nicklas, Barbara J.; DeVita, Paul; Beavers, Daniel P.; Hunter, David J.; Lyles, Mary F.; Eckstein, Felix; Williamson, Jeff D.; Carr, J. Jeffery; Guermazi, Ali; Loeser, Richard F.

    2015-01-01

    IMPORTANCE Knee osteoarthritis (OA), a common cause of chronic pain and disability, has biomechanical and inflammatory origins and is exacerbated by obesity. OBJECTIVE To determine whether a ≥10% reduction in body weight induced by diet, with or without exercise, would improve mechanistic and clinical outcomes more than exercise alone. DESIGN, SETTING, AND PARTICIPANTS Single-blind, 18-month, randomized clinical trial at Wake Forest University between July 2006 and April 2011. The diet and exercise interventions were center-based with options for the exercise groups to transition to a home-based program. Participants were 454 overweight and obese older community-dwelling adults (age ≥55 years with body mass index of 27–41) with pain and radiographic knee OA. INTERVENTIONS Intensive diet-induced weight loss plus exercise, intensive diet-induced weight loss, or exercise. MAIN OUTCOMES AND MEASURES Mechanistic primary outcomes: knee joint compressive force and plasma IL-6 levels; secondary clinical outcomes: self-reported pain (range, 0–20), function (range, 0–68), mobility, and health-related quality of life (range, 0–100). RESULTS At 18 months, 399 participants (88%) completed the study. Compared with exercise participants, knee compressive forces were lower in diet participants and IL-6 levels were lower in diet and diet + exercise participants. 18-mo Outcomes, Mean (95% CI) Exercise(E) Diet (D) D + E Difference,E vs D Difference, Evs D+E Weight loss, kg −1.8(−5.7to1.8) −8.9(−12.4 to −5.3) −10.6(−14.1 to −7.1) Knee compressiveforces, N 2687(2590 to 2784) 2487(2393 to 2581) 2543(2448 to 2637) 200(55 to 345)a 144(1 to 287) IL-6, pg/mL 3.1(2.9 to 3.4) 2.7(2.4 to 3.0) 2.7(2.5 to 3.0) 0.43(0.01 to 0.85)a 0.39(−0.03 to 0.81)a Pain 4.7(4.2 to 5.1) 4.8(4.3 to 5.2) 3.6(3.2 to 4.1) −0.11(−0.81 to 0.59) 1.02(0.33 to 1.71)a Function 18.4(16.9 to 19.9) 17.4(15.9 to 18.9) 14.1(12.6 to 15.6) 0.98(−1.24 to 3.20) 4.29(2.07 to 6.50)a SF-36

  12. A diffuse interface model of grain boundary faceting

    NASA Astrophysics Data System (ADS)

    Abdeljawad, F.; Medlin, D. L.; Zimmerman, J. A.; Hattar, K.; Foiles, S. M.

    2016-06-01

    Interfaces, free or internal, greatly influence the physical properties and stability of materials microstructures. Of particular interest are the processes that occur due to anisotropic interfacial properties. In the case of grain boundaries (GBs) in metals, several experimental observations revealed that an initially flat GB may facet into hill-and-valley structures with well defined planes and corners/edges connecting them. Herein, we present a diffuse interface model that is capable of accounting for strongly anisotropic GB properties and capturing the formation of hill-and-valley morphologies. The hallmark of our approach is the ability to independently examine the various factors affecting GB faceting and subsequent facet coarsening. More specifically, our formulation incorporates higher order expansions to account for the excess energy due to facet junctions and their non-local interactions. As a demonstration of the modeling capability, we consider the Σ5 <001 > tilt GB in body-centered-cubic iron, where faceting along the {210} and {310} planes was experimentally observed. Atomistic calculations were utilized to determine the inclination-dependent GB energy, which was then used as an input in our model. Linear stability analysis and simulation results highlight the role of junction energy and associated non-local interactions on the resulting facet length scales. Broadly speaking, our modeling approach provides a general framework to examine the microstructural stability of polycrystalline systems with highly anisotropic GBs.

  13. Facet-Dependent Cr(VI) Adsorption of Hematite Nanocrystals.

    PubMed

    Huang, Xiaopeng; Hou, Xiaojing; Song, Fahui; Zhao, Jincai; Zhang, Lizhi

    2016-02-16

    In this study, the adsorption process of Cr(VI) on the hematite facets was systematically investigated with synchrotron-based Cr K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, density-functional theory calculation, and surface complexation models. Structural model fitting of EXAFS spectroscopy suggested that the interatomic distances of Cr-Fe were, respectively, 3.61 Å for the chromate coordinated hematite nanoplates with exposed {001} facets, 3.60 and 3.30 Å for the chromate coordinated hematite nanorods with exposed {001} and {110} facets, which were characteristic of inner-sphere complexation. In situ ATR-FTIR spectroscopy analysis confirmed the presence of two inner-sphere surface complexes with C3ν and C2ν symmetry, while the C3ν and C2ν species were assigned to monodentate and bidentate inner-sphere surface complexes with average Cr-Fe interatomic distances of 3.60 and 3.30 Å, respectively. On the basis of these experimental and theoretical results, we concluded that HCrO4(-) as dominated Cr(VI) species was adsorbed on {001} and {110} facets in inner-sphere monodentate mononuclear and bidentate binuclear configurations, respectively. Moreover, the Cr(VI) adsorption performance of hematite facets was strongly dependent on the chromate complexes formed on the hematite facets. PMID:26815307

  14. A diffuse interface model of grain boundary faceting

    NASA Astrophysics Data System (ADS)

    Abdeljawad, Fadi; Medlin, Douglas; Zimmerman, Jonathan; Hattar, Khalid; Foiles, Stephen

    Incorporating anisotropy into thermodynamic treatments of interfaces dates back to over a century ago. For a given orientation of two abutting grains in a pure metal, depressions in the grain boundary (GB) energy may exist as a function of GB inclination, defined by the plane normal. Therefore, an initially flat GB may facet resulting in a hill-and-valley structure. Herein, we present a diffuse interface model of GB faceting that is capable of capturing anisotropic GB energies and mobilities, and accounting for the excess energy due to facet junctions and their non-local interactions. The hallmark of our approach is the ability to independently examine the role of each of the interface properties on the faceting behavior. As a demonstration, we consider the Σ 5 < 001 > tilt GB in iron, where faceting along the { 310 } and { 210 } planes was experimentally observed. Linear stability analysis and numerical examples highlight the role of junction energy and associated non-local interactions on the resulting facet length scales. On the whole, our modeling approach provides a general framework to examine the spatio-temporal evolution of highly anisotropic GBs in polycrystalline metals. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  15. Ceramic joints

    DOEpatents

    Miller, Bradley J.; Patten, Jr., Donald O.

    1991-01-01

    Butt joints between materials having different coefficients of thermal expansion are prepared having a reduced probability of failure of stress facture. This is accomplished by narrowing/tapering the material having the lower coefficient of thermal expansion in a direction away from the joint interface and not joining the narrow-tapered surface to the material having the higher coefficient of thermal expansion.

  16. Structural Equation Modelling of Multiple Facet Data: Extending Models for Multitrait-Multimethod Data

    ERIC Educational Resources Information Center

    Bechger, Timo M.; Maris, Gunter

    2004-01-01

    This paper is about the structural equation modelling of quantitative measures that are obtained from a multiple facet design. A facet is simply a set consisting of a finite number of elements. It is assumed that measures are obtained by combining each element of each facet. Methods and traits are two such facets, and a multitrait-multimethod…

  17. Beyond Text Queries and Ranked Lists: Faceted Search in Library Catalogs

    ERIC Educational Resources Information Center

    Niu, Xi

    2012-01-01

    Since the adoption of faceted search in a small number of academic libraries in 2006, faceted library catalogs have gained popularity in many academic and public libraries. This dissertation seeks to understand whether faceted search improves the interactions between searchers and library catalogs and to understand ways that facets are used in…

  18. Faceted Visualization of Three Dimensional Neuroanatomy By Combining Ontology with Faceted Search

    PubMed Central

    Veeraraghavan, Harini; Miller, James V.

    2013-01-01

    In this work, we present a faceted-search based approach for visualization of anatomy by combining a three dimensional digital atlas with an anatomy ontology. Specifically, our approach provides a drill-down search interface that exposes the relevant pieces of information (obtained by searching the ontology) for a user query. Hence, the user can produce visualizations starting with minimally specified queries. Furthermore, by automatically translating the user queries into the controlled terminology our approach eliminates the need for the user to use controlled terminology. We demonstrate the scalability of our approach using an abdominal atlas and the same ontology. We implemented our visualization tool on the opensource 3D Slicer software. We present results of our visualization approach by combining a modified Foundational Model of Anatomy (FMA) ontology with the Surgical Planning Laboratory (SPL) Brain 3D digital atlas, and geometric models specific to patients computed using the SPL brain tumor dataset. PMID:24006207

  19. A Better Quick-Connect Passive Capture Joint

    NASA Technical Reports Server (NTRS)

    Nabors, Sammy A.

    2015-01-01

    NASA's Marshall Space Flight Center has developed a joint that employs a unique spring-loaded mechanism that automatically secures a ball hitch upon insertion into a coupler. This eliminates the need for the locking lever found in most conventional ball joints. Connections made using MSFC's quick-connect joint are easier, safer, and more reliable than those made using conventional ball joints.

  20. Temporomandibular Joint, Closed

    MedlinePlus

    ... Oral Health > The Temporomandibular Joint, Closed The Temporomandibular Joint, Closed Main Content Title: The Temporomandibular Joint, Closed Description: The temporomandibular joint connects the lower ...

  1. Arthroscopic management of volar lunate facet fractures of the distal radius.

    PubMed

    Wiesler, Ethan R; Chloros, George D; Lucas, Robert M; Kuzma, Gary R

    2006-09-01

    The clinical outcome of an intraarticular distal radius fracture is generally thought to be associated with the following factors: amount of radial deformity, joint congruity, and associated soft-tissue injuries. The proposed technique to manage this fracture pattern that involves a displaced volar lunate facet fragment uses wrist arthroscopy and pinning. Distraction of the fracture before arthroscopy is accomplished either by external fixation or by the arthroscopy tower. A freer elevator is introduced dorsally to disimpact the fragments, and next, a nerve hook is used to reduce the volar lunate facet, which is subsequently pinned to the radial styloid. The remaining fragments are reduced with interfragmentary pin fixation, and this anatomical articular construct is fixed to the radial metaphysis. The advantages of this technique are: (a) accurate assessment of articular congruency by direct visualization, (b) identification and repair of associated lesions, and (c) minimal soft tissue disruption. Potential disadvantages of external fixation supplemented by interfragmentary pins may be that it does not provide for rigid stable fixation, and therefore, does not allow for early motion compared to open reduction and internal fixation. Furthermore, it is technically challenging, and is therefore suggested as an alternative for the aforementioned fracture pattern. PMID:16974217

  2. Investigating facets of personality in adult pathological gamblers with ADHD

    PubMed Central

    Davtian, Margarit; Reid, Rory C; Fong, Timothy W

    2012-01-01

    SUMMARY The present study explored facets of personality in a sample of pathological gamblers with ADHD (n = 52) and without ADHD (n = 43). Participants were assessed for psychopathology and gambling disorders using the Mini International Neuropsychiatric Interview, the National Opinion Research Center DSM Screen for Gambling Problems, and the Adult ADHD Self-Report Scale. Facets of personality were assessed using the NEO Personality Inventory–Revised. Group differences emerged across several facets of personality when analyzed using multivariate statistics. Although both groups experienced difficulties in several areas compared with norming data (e.g., greater depression, higher impulsivity, lower self-esteem and lower self-discipline), these facets of personality were more pronounced in pathological gamblers with ADHD. Most notable among these differences are tendencies for gamblers with ADHD to experience greater levels of emotional instability, interpersonal sensitivity and stress proneness. Pathological gamblers with ADHD also appear to experience lower self-esteem, greater difficulty being assertive and lower levels of self-discipline. Surprisingly, both groups were comparable on facets of impulsivity. These findings suggest that pathological gamblers diagnosed with adult ADHD may experience additional challenges compared with pathological gamblers without ADHD. PMID:22815658

  3. Simulation and optimization of faceted structure for illumination

    NASA Astrophysics Data System (ADS)

    Liu, Lihong; Engel, Thierry; Flury, Manuel

    2016-04-01

    The re-direction of incoherent light using a surface containing only facets with specific angular values is proposed. A new photometric approach is adopted since the size of each facet is large in comparison with the wavelength. A reflective configuration is employed to avoid the dispersion problems of materials. The irradiance distribution of the reflected beam is determined by the angular position of each facet. In order to obtain the specific irradiance distribution, the angular position of each facet is optimized using Zemax OpticStudio 15 software. A detector is placed in the direction which is perpendicular to the reflected beam. According to the incoherent irradiance distribution on the detector, a merit function needs to be defined to pilot the optimization process. The two dimensional angular position of each facet is defined as a variable which is optimized within a specified varying range. Because the merit function needs to be updated, a macro program is carried out to update this function within Zemax. In order to reduce the complexity of the manual operation, an automatic optimization approach is established. Zemax is in charge of performing the optimization task and sending back the irradiance data to Matlab for further analysis. Several simulation results are given for the verification of the optimization method. The simulation results are compared to those obtained with the LightTools software in order to verify our optimization method.

  4. Noble-Metal Nanocrystals with Controlled Facets for Electrocatalysis.

    PubMed

    Hong, Jong Wook; Kim, Yena; Kwon, Yongmin; Han, Sang Woo

    2016-08-19

    Noble-metal nanocrystals (NCs) show excellent catalytic performance for many important electrocatalysis reactions. The crystallographic properties of the facets by which the NCs are bound, closely associated with the shape of the NCs, have a profound influence on the electrocatalytic function of the NCs. To develop an efficient strategy for the synthesis of NCs with controlled facets as well as compositions, understanding of the growth mechanism of the NCs and their interaction with the chemical species involved in NC synthesis is quite important. Furthermore, understanding the facet-dependent catalytic properties of noble-metal NCs and the corresponding mechanisms for various electrocatalysis reactions will allow for the rational design of robust electrocatalysts. In this review, we summarize recently developed synthesis strategies for the preparation of mono- and bimetallic noble-metal NCs by classifying them by the type of facets through which they are enclosed and discuss the electrocatalytic applications of noble-metal NCs with controlled facets, especially for reactions associated with fuel-cell applications, such as the oxygen reduction reaction and fuel (methanol, ethanol, and formic acid) oxidation reactions. PMID:27258679

  5. Modeling of Anomalous Transport in Tokamaks with FACETS code

    NASA Astrophysics Data System (ADS)

    Pankin, A. Y.; Batemann, G.; Kritz, A.; Rafiq, T.; Vadlamani, S.; Hakim, A.; Kruger, S.; Miah, M.; Rognlien, T.

    2009-05-01

    The FACETS code, a whole-device integrated modeling code that self-consistently computes plasma profiles for the plasma core and edge in tokamaks, has been recently developed as a part of the SciDAC project for core-edge simulations. A choice of transport models is available in FACETS through the FMCFM interface [1]. Transport models included in FMCFM have specific ranges of applicability, which can limit their use to parts of the plasma. In particular, the GLF23 transport model does not include the resistive ballooning effects that can be important in the tokamak pedestal region and GLF23 typically under-predicts the anomalous fluxes near the magnetic axis [2]. The TGLF and GYRO transport models have similar limitations [3]. A combination of transport models that covers the entire discharge domain is studied using FACETS in a realistic tokamak geometry. Effective diffusivities computed with the FMCFM transport models are extended to the region near the separatrix to be used in the UEDGE code within FACETS. 1. S. Vadlamani et al. (2009) %First time-dependent transport simulations using GYRO and NCLASS within FACETS (this meeting).2. T. Rafiq et al. (2009) %Simulation of electron thermal transport in H-mode discharges Submitted to Phys. Plasmas.3. C. Holland et al. (2008) %Validation of gyrokinetic transport simulations using %DIII-D core turbulence measurements Proc. of IAEA FEC (Switzerland, 2008)

  6. Facet-sparing lumbar decompression with a minimally invasive flexible MicroBlade Shaver® versus traditional decompression: quantitative radiographic assessment

    PubMed Central

    Lauryssen, Carl; Berven, Sigurd; Mimran, Ronnie; Summa, Christopher; Sheinberg, Michael; Miller, Larry E; Block, Jon E

    2012-01-01

    Background Laminectomy/laminotomy and foraminotomy are well established surgical techniques for treatment of symptomatic lumbar spinal stenosis. However, these procedures have significant limitations, including limited access to lateral and foraminal compression and postoperative instability. The purpose of this cadaver study was to compare bone, ligament, and soft tissue morphology following lumbar decompression using a minimally invasive MicroBlade Shaver® instrument versus hemilaminotomy with foraminotomy (HL). Methods The iO-Flex® system utilizes a flexible over-the-wire MicroBlade Shaver instrument designed for facet-sparing, minimally invasive “inside-out” decompression of the lumbar spine. Unilateral decompression was performed at 36 levels in nine human cadaver specimens, six with age-appropriate degenerative changes and three with radiographically confirmed multilevel stenosis. The iO-Flex system was utilized on alternating sides from L2/3 to L5/S1, and HL was performed on the opposite side at each level by the same investigator. Spinal canal, facet joint, lateral recess, and foraminal morphology were assessed using computed tomography. Results Similar increases in soft tissue canal area and decreases in ligamentum flavum area were noted in nondiseased specimens, although HL required removal of 83% more laminar area (P < 0.01) and 95% more bone resection, including the pars interarticularis and facet joints (P < 0.001), compared with the iO-Flex system. Similar increases in lateral recess diameter were noted in nondiseased specimens using each procedure. In stenotic specimens, the increase in lateral recess diameter was significantly (P = 0.02) greater following use of the iO-Flex system (43%) versus HL (7%). The iO-Flex system resulted in greater facet joint preservation in nondiseased and stenotic specimens. In stenotic specimens, the iO-Flex system resulted in a significantly greater increase in foraminal width compared with HL (24% versus 4%, P

  7. Shock transmissibility of threaded joints

    SciTech Connect

    Hansen, N.R.; Bateman, V.I.; Brown, F.A.

    1996-12-31

    Sandia National Laboratories (SNL) designs mechanical systems with threaded joints that must survive high shock environments. These mechanical systems include penetrators that must survive soil and rock penetration; drilling pipe strings that must survive rock-cutting, shock environments; and laydown weapons that must survive delivery impact shock. This paper summarizes an analytical study and an experimental evaluation of compressive, one-dimensional, shock transmission through a threaded joint in a split Hopkinson bar configuration. Thread geometries were scaled to simulate large diameter threaded joints with loadings parallel to the axis of the threads. Both strain and acceleration were evaluated with experimental measurements and analysis. Analytical results confirm the experimental conclusions that in this split Hopkinson bar configuration, the change in the one-dimensional shock wave by the threaded joint is localized to a length equal to a few diameters` length beyond the threaded joint.

  8. Joint Problems

    MedlinePlus

    ... ankles and toes. Other types of arthritis include gout or pseudogout. Sometimes, there is a mechanical problem ... for more information on osteoarthritis, rheumatoid arthritis and gout. How Common are Joint Problems? Osteoarthritis, which affects ...

  9. Joint pain

    MedlinePlus

    ... or conditions. It may be linked to arthritis , bursitis , and muscle pain . No matter what causes it, ... Autoimmune diseases such as rheumatoid arthritis and lupus Bursitis Chondromalacia patellae Crystals in the joint: gout (especially ...

  10. Compliant joint

    NASA Technical Reports Server (NTRS)

    Eklund, Wayne D. (Inventor); Kerley, James J. (Inventor)

    1990-01-01

    A compliant joint is provided for prosthetic and robotic devices which permits rotation in three different planes. The joint provides for the controlled use of cable under motion. Perpendicular outer mounting frames are joined by swaged cables that interlock at a center block. Ball bearings allow for the free rotation of the second mounting frame relative to the first mounting frame within a predetermined angular rotation that is controlled by two stop devices. The cables allow for compliance at the stops and the cables allow for compliance in six degrees of freedom enabling the duplication or simulation of the rotational movement and flexibility of a natural hip or knee joint, as well as the simulation of a joint designed for a specific robotic component for predetermined design parameters.

  11. On the creep constrained diffusive cavitation of grain boundary facets

    NASA Astrophysics Data System (ADS)

    Tvergaard, Viggo

    CREEP rupture in a polycrystalline metal at a high temperature, by cavity growth on a number of grain boundary facets, is studied numerically. An axisymmetric model problem is analysed, in which a cavitating facet is represented as disk-shaped, and the model dimensions are taken to represent spacings between neighbouring cavitating facets. For the grains both power law creep and elastic deformations are taken into account, and the description of cavity growth is based on an approximate expression that incorporates the coupled influence of grain boundary diffusion and power law creep. The cases considered include creep-constrained cavity growth at low stresses, where the voids link up to form grain boundary cracks at relatively small overall strains, as well as the power law creep dominated behaviour at higher stress levels, where rupture occurs at large overall strains. The numerical results are compared with results based on various simplified analyses.

  12. Titanium dioxide nanoswords with highly reactive, photocatalytic facets

    NASA Astrophysics Data System (ADS)

    Sosnowchik, Brian D.; Chiamori, Heather C.; Ding, Yong; Ha, Jong-Yoon; Wang, Zhong Lin; Lin, Liwei

    2010-12-01

    Titanium dioxide (TiO2) is one of the most widely studied and important materials for catalysis, photovoltaics, and surface science applications, but the ability to consistently control the relative exposure of higher surface energy facets during synthesis remains challenging. Here, we present the repeatable synthesis of highly reactive, rutile {001} or {101} facets on broad, sword-shaped TiO2 nanostructures rapidly synthesized in minutes. Growth occurs along planes of lower surface energy, repeatedly yielding nanostructures with large, high energy facets. The quantitative photocatalytic reactivity of the nanoswords, demonstrated by the photoreduction of silver, is over an order of magnitude higher than reference low energy TiO2{110} substrates. Therefore, the higher surface energy dominated TiO2 nanoswords are ideal structures for characterizing the physicochemical properties of rutile TiO2, and may be used to enhance a variety of catalytic, optical, and clean-technology applications.

  13. Quantitative modeling of facet development in ventifacts by sand abrasion

    NASA Astrophysics Data System (ADS)

    Várkonyi, Péter L.; Laity, Julie E.; Domokos, Gábor

    2016-03-01

    We use a quantitative model to examine rock abrasion by direct impacts of sand grains. Two distinct mechanisms are uncovered (unidirectional and isotropic), which contribute to the macro-scale morphological characters (sharp edges and flat facets) of ventifacts. It is found that facet formation under conditions of a unidirectional wind relies on certain mechanical properties of the rock material, and we confirm the dominant role of this mechanism in the formation of large ventifacts. Nevertheless small ventifacts may also be shaped to polyhedral shapes in a different way (isotropic mechanism), which is not sensitive to wind characteristics nor to rock material properties. The latter mechanism leads to several 'mature' shapes, which are surprisingly analogous to the morphologies of typical small ventifacts. Our model is also able to explain certain quantitative laboratory and field observations, including quick decay of facet angles of ventifacts followed by stabilization in the range 20-30°.

  14. Hierarchical structures of rutile exposing high-index facets

    NASA Astrophysics Data System (ADS)

    Truong, Quang Duc; Kato, Hideki; Kobayashi, Makoto; Kakihana, Masato

    2015-05-01

    Recently, shape-controlled synthesis of crystals exposing high-index facets has attracted much research interest due to their importance for both fundamental studies and technological applications. Herein, crystals of rutile-type TiO2 with hierarchical structures exposing high-index facets have been synthesized by a facile hydrothermal method using water-soluble titanium complex as a precursor and picolinic acid as structure-directing and shape-controlling agents. The synthesized particles were composed of several branches of pyramidal crystals with relatively smooth surface. On the basis of investigation results, it was speculated that the mutual π-stacking and selective adsorption of picolinic acid on specific {111} facets resulted in the formation of rutile crystals bound by high-index surfaces such as {331}.

  15. Mapping Mindfulness Facets onto Dimensions of Anxiety and Depression

    PubMed Central

    Desrosiers, Alethea; Klemanski, David H.; Nolen-Hoeksema, Susan

    2014-01-01

    Background Mindfulness has been associated with anxiety and depression, but the ways in which specific facets of mindfulness relate to symptoms of anxiety and depression remains unclear. The purpose of the current study was to investigate associations between specific facets of mindfulness (e.g., observing, describing, nonjudging, acting with awareness, and nonreactivity) and dimensions of anxiety and depression symptoms (e.g., anxious arousal, general distress-anxiety, general distress-depression, and anhedonic depression) while controlling for shared variance among variables. Methods Participants were 187 treatment-seeking adults. Mindfulness was measured using the Five Facet Mindfulness Questionnaire and symptoms of depression and anxiety were measured using the Mood and Anxiety Symptom Questionnaire. Results Bivariate correlations showed that all facets of mindfulness were significantly related to all dimensions of anxiety and depression with two exceptions: describing was unrelated to general distress -anxiety, and observing was unrelated to all symptom clusters. Path analysis was used to simultaneously examine associations between mindfulness facets and depression and anxiety symptoms. Significant and marginally significant pathways were retained to construct a more parsimonious model and model fit indices were examined. The parsimonious model indicated that nonreactivity was significantly inversely associated with general distress anxiety symptoms. Describing was significantly inversely associated with anxious arousal, while observing was significantly positively associated with it. Nonjudging and nonreactivity were significantly inversely related to general distress-depression and anhedonic depression symptomatology. Acting with awareness was not significantly associated with any dimensions of anxiety or depression. Conclusions Findings support associations between specific facets of mindfulness and dimensions of anxiety and depression and highlight the

  16. Faceted spurs at normal fault scarps: Insights from numerical modeling

    NASA Astrophysics Data System (ADS)

    Petit, C.; Gunnell, Y.; Gonga-Saholiariliva, N.; Meyer, B.; SéGuinot, J.

    2009-05-01

    We present a combined surface processes and tectonic model which allows us to determine the climatic and tectonic parameters that control the development of faceted spurs at normal fault scarps. Sensitivity tests to climatic parameter values are performed. For a given precipitation rate, when hillslope diffusion is high and channel bedrock is highly resistant to erosion, the scarp is smooth and undissected. When, instead, the bedrock is easily eroded and diffusion is limited, numerous channels develop and the scarp becomes deeply incised. Between these two end-member states, diffusion and incision compete to produce a range of scarp morphologies, including faceted spurs. The sensitivity tests allow us to determine a dimensionless ratio of erosion, f, for which faceted spurs can develop. This study evidences a strong dependence of facet slope angle on throw rate for throw rates between 0.4 and 0.7 mm/a. Facet height is also shown to be a linear function of fault throw rate. Model performance is tested on the Wasatch Fault, Utah, using topographic, geologic, and seismologic data. A Monte Carlo inversion on the topography of a portion of the Weber segment shows that the 5 Ma long development of this scarp has been dominated by a low effective precipitation rate (˜1.1 m/a) and a moderate diffusion coefficient (0.13 m2/a). Results demonstrate the ability of our model to estimate normal fault throw rates from the height of triangular facets and to retrieve the average long-term diffusion and incision parameters that prevailed during scarp evolution using an accurate 2-D misfit criterion.

  17. Photonic Waveguide Choke Joint with Absorptive Loading

    NASA Technical Reports Server (NTRS)

    Wollack, Edward J. (Inventor); U-Yen, Kongpop (Inventor); Chuss, David T. (Inventor)

    2016-01-01

    A photonic waveguide choke includes a first waveguide flange member having periodic metal tiling pillars, a dissipative dielectric material positioned within an area between the periodic metal tiling pillars and a second waveguide flange member disposed to be coupled with the first waveguide flange member and in spaced-apart relationship separated by a gap. The first waveguide flange member has a substantially smooth surface, and the second waveguide flange member has an array of two-dimensional pillar structures formed therein.

  18. Development of an improved mirror facet for space applications

    NASA Technical Reports Server (NTRS)

    Schertz, Paul; Saifee, Shabbar; Lammert, Luke

    1991-01-01

    A fabrication technique was successfully developed for a metallic aluminum honeycomb, high-accuracy, lightweight, and long-life solar concentrator (mirror) for Advanced Solar Dynamic Space Power Systems. The program scope was limited to the development, fabrication, evaluation, and delivery of a solar concentrator facet (petal) that was sized for a 2-meter deployable solar concentrator. A surface accuracy of 1.0 mrad was achieved. The development incorporated tooling design, material selection, facet forming, adhesive selection, testing, and analysis. Techniques for applying levelizing, reflective, and protective optical coatings were also developed.

  19. From facets to facets: how does work function vary over a gold nanocluster?

    NASA Astrophysics Data System (ADS)

    Gao, Lingyuan; Souto, Jaime; Chelikowsky, James; Demkov, Alex

    Owing to their potential applications in catalysis, gold nanoclusters are a focus of intense research. The work function Φ, which can be measured using photoemission spectroscopy is a key parameter used to characterize the catalytic performance of the cluster. Φ is determined by the difference between the electrostatic potential just outside the metal surface and the Fermi energy of the cluster. We use a relativistic version of the real space first-principles code PARSEC to compute the work function of gold nanoclusters with dimensions on the order of a nanometer, which is similar in size to those used in experiment. We illustrate how the work function depends on the surface orientation of the nanocluster facets and compare our results with available experimental data We acknowledge supports from SciDAC program, Department of Energy, Office of Science, Advanced Scientific Computing Research and Basic Energy Sciences grant DE-SC0008877 for work on algorithms. Two of us (JRC and JS-C) acknowledge support for the work on nanostructures from grant from the U.S. Department of Energy: DE-FG02-06ER46286.

  20. Postero-Lateral Disc Prosthesis Combined With a Unilateral Facet Replacement Device Maintains Quantity and Quality of Motion at a Single Lumbar Level

    PubMed Central

    Nayak, Aniruddh N.; Doarn, Michael C.; Gaskins, Roger B.; James, Chris R.; Cabezas, Andres F.; Castellvi, Antonio E.

    2014-01-01

    Background Mechanically replacing one or more pain generating articulations in the functional spinal unit (FSU) may be a motion preservation alternative to arthrodesis at the affected level. Baseline biomechanical data elucidating the quantity and quality of motion in such arthroplasty constructs is non-existent. Purpose The purpose of the study was to quantify the motion-preserving effect of a posterior total disc replacement (PDR) combined with a unilateral facet replacement (FR) system at a single lumbar level (L4-L5). We hypothesized that reinforcement of the FSU with unilateral FR to replace the resected, native facet joint following PDR implantation would restore quality and quantity of motion and additionally not change biomechanics at the adjacent levels. Study Design In-vitro study using human cadaveric lumbar spines. Methods Six (n = 6) cadaveric lumbar spines (L1-S1) were evaluated using a pure-moment stability testing protocol (±7.5 Nm) in flexion-extension (F/E), lateral bending (LB) and axial rotation (AR). Each specimen was tested in: (1) intact; (2) unilateral FR; and (3) unilateral FR + PDR conditions. Index and adjacent level ROM (using hybrid protocol) were determined opto-electronically. Interpedicular travel (IPT) and instantaneous center of rotation (ICR) at the index level were radiographically determined for each condition. ROM, ICR, and IPT measurements were compared (repeated measures ANOVA) between the three conditions. Results Compared to the intact spine, no significant changes in F/E, LB or AR ROM were identified as a result of unilateral FR or unilateral FR + PDR. No significant changes in adjacent L3-L4 or L5-S1 ROM were identified in any loading mode. No significant differences in IPT were identified between the three test conditions in F/E, LB or AR at the L4-L5 level. The ICRs qualitatively were similar for the intact and unilateral FR conditions and appeared to follow placement (along the anterior-posterior (AP) direction) of

  1. Shear joint capability versus bolt clearance

    NASA Technical Reports Server (NTRS)

    Lee, H. M.

    1992-01-01

    The results of a conservative analysis approach into the determination of shear joint strength capability for typical space-flight hardware as a function of the bolt-hole clearance specified in the design are presented. These joints are comprised of high-strength steel fasteners and abutments constructed of aluminum alloys familiar to the aerospace industry. A general analytical expression was first arrived at which relates bolt-hole clearance to the bolt shear load required to place all joint fasteners into a shear transferring position. Extension of this work allowed the analytical development of joint load capability as a function of the number of fasteners, shear strength of the bolt, bolt-hole clearance, and the desired factor of safety. Analysis results clearly indicate that a typical space-flight hardware joint can withstand significant loading when less than ideal bolt hole clearances are used in the design.

  2. Long-range surface faceting induced by chemisorption of PTCDA on stepped Ag(111) surfaces

    NASA Astrophysics Data System (ADS)

    Schmitt, Stefan; Schöll, Achim; Umbach, Eberhard

    2016-01-01

    The organic molecule PTCDA preferentially adsorbs on steps of vicinal Ag(111) surfaces and bunches them to well defined facet planes. These depend on coverage and annealing temperature and are independent of the nominal step direction and angle of inclination of the unreconstructed initial surface. We study the development of the facets and present a map of all 16 types of facets in a stereographic triangle of 35° off the [111]-direction. The faceting mechanism is interpreted as orientational phase separation originating from different bonding strengths of PTCDA on various facets. The faceting drives the system to the minimum of its surface free energy.

  3. Tubular lap joints for wind turbine applications

    SciTech Connect

    Reedy, E.D. Jr.; Guess, T.R.

    1990-01-01

    A combined analytical/experimental study of the strength of thick- walled, adhesively bonded PMMA-to-aluminum and E-glass/epoxy composite-to-aluminum tubular lap joints under axial load has been conducted. Test results include strength and failure mode data. Moreover, strain gages placed along the length of the outer tubular adherend characterize load transfer from one adherend to the other. The strain gage data indicate that load transfer is nonuniform and that the relatively compliant PMMA has the shorter load transfer length. Strains determined by a finite element analysis of the tested joints are in excellent agreement with those measured. Calculated bond stresses are highest in the region of observed failure, and extensive bond yielding is predicted in the E- glass/epoxy composite-to-aluminum joint prior to joint failure. 4 refs., 13 figs., 1 tab.

  4. Improved Automatically Locking/Unlocking Orthotic Knee Joint

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce

    1995-01-01

    Proposed orthotic knee joint improved version of one described in "Automatically Locking/Unlocking Orthotic Knee Joint" (MFS-28633). Locks automatically upon initial application of radial force (wearer's weight) and unlocks automatically, but only when all loads (radial force and bending) relieved. Joints lock whenever wearer applies weight to knee at any joint angle between full extension and 45 degree bend. Both devices offer increased safety and convenience relative to conventional orthotic knee joints.

  5. Imaging of posterior element axial pain generators: facet joints, pedicles, spinous processes, sacroiliac joints, and transitional segments.

    PubMed

    Kotsenas, Amy L

    2012-07-01

    The role of the posterior elements in generating axial back and neck pain is well established; the imaging detection of posterior element pain generators remains problematic. Morphologic imaging findings have proved to be nonspecific and are frequently present in asymptomatic patients. Edema, inflammation, and hypervascularity are more specific for sites of pain generation, but are often overlooked by imagers if physiologic imaging techniques such as fat-suppressed T2 or contrast-enhanced T1-weighted magnetic resonance imaging, radionuclide bone scanning with single-photon emission computed tomography (CT), or (18)F-fluorodeoxyglucose positron emission tomography combined with CT are not used. PMID:22643392

  6. The Cool and Belkin Faceted Classification of Information Interactions Revisited

    ERIC Educational Resources Information Center

    Huvila, Isto

    2010-01-01

    Introduction: The complexity of human information activity is a challenge for both practice and research in information sciences and information management. Literature presents a wealth of approaches to analytically structure and make sense of human information activity including a faceted classification model of information interactions published…

  7. Facets of the Geography of Population in the Midwest.

    ERIC Educational Resources Information Center

    Hart, John Fraser

    1986-01-01

    Explores four selected facets of the geography of Midwest population related to movement of people: (1) spread of occupancy across the land; (2) growth of county populations once they had been occupied; (3) distribution of the foreign-born population; and (4) distribution of retirees who have migrated after retirement. Concludes movements are…

  8. Progress of plasma wakefield self-modulation experiments at FACET

    NASA Astrophysics Data System (ADS)

    Adli, E.; Berglyd Olsen, V. K.; Lindstrøm, C. A.; Muggli, P.; Reimann, O.; Vieira, J. M.; Amorim, L. D.; Clarke, C. I.; Gessner, S. J.; Green, S. Z.; Hogan, M. J.; Litos, M. D.; O`Shea, B. D.; Yakimenko, V.; Clayton, C.; Marsh, K. A.; Mori, W. B.; Joshi, C.; Vafaei-Najafabadi, N.; Williams, O.

    2016-09-01

    Simulations and theory predict that long electron and positron beams may under favorable conditions self-modulate in plasmas. We report on the progress of experiments studying the self-modulation instability in plasma wakefield experiments at FACET. The experimental results obtained so far, while not being fully conclusive, appear to be consistent with the presence of the self-modulation instability.

  9. Beyond Conflict: Functional Facets of the Work-Family Interplay

    ERIC Educational Resources Information Center

    Wiese, Bettina S.; Seiger, Christine P.; Schmid, Christian M.; Freund, Alexandra M.

    2010-01-01

    The present paper deals with three positive facets of the work-family interplay, i.e., transfer of competencies, transfer of positive mood, and cross-domain compensation. The latter refers to the experience that engagement in one domain helps dealing with failures in the other domain. In two correlational studies (N[subscript 1] = 107 working…

  10. Empirical Identification of the Major Facets of Conscientiousness

    ERIC Educational Resources Information Center

    MacCann, Carolyn; Duckworth, Angela Lee; Roberts, Richard D.

    2009-01-01

    Conscientiousness is often found to predict academic outcomes, but is defined differently by different models of personality. High school students (N = 291) completed a large number of Conscientiousness items from different models and the Big Five Inventory (BFI). Exploratory and confirmatory factor analysis of the items uncovered eight facets:…

  11. Conceptualizing Educational Leadership: Does Exploring Macro-Level Facets Matters?

    ERIC Educational Resources Information Center

    Sinha, Chetan

    2013-01-01

    The present review attempts to examine the present status of educational leadership highlighting the role of macro-level facets in Asian Pacific context. The conceptualization of educational leadership among researchers so far had been found to vary according to different contexts and situations. Theoretical perspectives associated with…

  12. Hinge specification for a square-faceted tetrahedral truss

    NASA Technical Reports Server (NTRS)

    Adams, L. R.

    1984-01-01

    A square-faceted tetrahedral truss is geometrically analyzed. Expressions are developed for single degree of freedom hinges which allow packaging of the structure into a configuration in which all members are parallel and closely packed in a square pattern. Deployment is sequential, thus providing control over the structure during deployment.

  13. Transverse oscillations in plasma wakefield experiments at FACET

    NASA Astrophysics Data System (ADS)

    Adli, E.; Lindstrøm, C. A.; Allen, J.; Clarke, C. I.; Frederico, J.; Gessner, S. J.; Green, S. Z.; Hogan, M. J.; Litos, M. D.; White, G. R.; Yakimenko, V.; An, W.; Clayton, C. E.; Marsh, K. A.; Mori, W. B.; Joshi, C.; Vafaei-Najafabadi, N.; Corde, S.; Lu, W.

    2016-09-01

    We study transverse effects in a plasma wakefield accelerator. Experimental data from FACET with asymmetry in the beam-plasma system is presented. Energy dependent centroid oscillations are observed on the accelerated part of the charge. The experimental results are compared to PIC simulations and theoretical estimates.

  14. Personality Facets and RIASEC Interests: An Integrated Model

    ERIC Educational Resources Information Center

    Armstrong, Patrick Ian; Anthoney, Sarah Fetter

    2009-01-01

    Research examining links between personality and interest have typically focused on links between measures of the five factor model and Holland's RIASEC types. However, the five factor model of personality can be divided in to a larger set of narrow domain personality scales measuring facets of the "big five" traits. Research in a number of fields…

  15. Rare Thoracolumbar Facet Synovial Cyst Presenting as Paraparesis

    PubMed Central

    Dahuja, Gitanshu; Kaur, Rashmeet

    2015-01-01

    Spinal cord compressing syndrome due to synovial cyst (SC) of the thoracolumbar spine is a rare clinical condition. In this report we aim to heighten awareness of the thoracolumbar facet synovial cyst as a possible cause of thoracic myelopathy. The SC was removed thoroughly by laminectomy. The patient had an excellent recovery. The etiological and therapeutic aspects are discussed. PMID:26512282

  16. Examining Student Rating of Teaching Effectiveness Using FACETS

    ERIC Educational Resources Information Center

    Mat Daud, Nuraihan; Abu Kassim, Noor Lide

    2011-01-01

    Students' evaluations of teaching staff can be considered high-stakes, as they are often used to determine promotion, reappointment, and merit pay to academics. Using Facets, the reliability and validity of one student rating questionnaire is analysed. A total of 13,940 respondents of the Human Science Division of International Islamic University…

  17. MULTI-FACETED SUSTAINABILITY ON ITHACA COLLEGE NATURAL LANDS

    EPA Science Inventory

    This student-generated proposal presents a multi-faceted program for sustainable stewardship of the natural areas south of the built campus of Ithaca College. Our challenge is to use student research and class projects to enhance biodiversity, support education and research, and...

  18. Strength evaluation of socket joints

    NASA Technical Reports Server (NTRS)

    Rash, Larry C.

    1994-01-01

    This report documents the development of a set of equations that can be used to provide a relatively simple solution for identifying the strength of socket joints and for most cases avoid the need of more lengthy analyses. The analytical approach was verified by comparison of the contact load distributions to results obtained from a finite element analysis. The contacting surfaces for the specific joint in this analysis are in the shape of frustrums of a cone and are representative of the tapered surfaces in the socket-type joints used to join segments of model support systems for wind tunnels. The results are in the form of equations that can be used to determine the contact loads and stresses in the joint from the given geometry and externally applied loads. Equations were determined to define the bending moments and stresses along the length of the joints based on strength and materials principles. The results have also been programmed for a personal computer and a copy of the program is included.

  19. Well pipe joint

    SciTech Connect

    Ortloff, D.J.; Landriault, L.S.

    1987-08-25

    For use in forming a pipe joint, a threaded tubular member adapted for connecting to another threaded member to form a threaded connection between the two members is described comprising a tubular body, a projecting helical rib on the body forming screw threads having load flanks shaped to have clearance between the flanks of the thread and the load flanks of the threads of the threaded member to which the member is adapted to be connected and a torque shoulder on the body to engage a torque shoulder on the other threaded member as the connection is being made up to limit the distance one of the members can enter the other for a given make-up torque. The threads are formed on the body so that selected threads away from the torque shoulder will have less clearance between them and the mating threads on the other member than do the threads on the member adjacent the torque shoulder and the mating threads on the other member when the torque shoulders engage so that the selected threads will engage the mating threads on the other member before the other threads adjacent the torque shoulder and the mating threads on the other member engage to cause the selected threads to be loaded initially to provide the initial force between the torque shoulders and to more uniformly load all of the threads when the connection is made-up and additional external loads are applied.

  20. Joint shear strength of FRP reinforced concrete beam-column joints

    NASA Astrophysics Data System (ADS)

    Saravanan, Jagadeesan; Kumaran, Ganapathy

    2011-03-01

    An assessment of the joint shear strength of exterior concrete beam-column joints reinforced internally with Glass Fibre Reinforced Polymer (GFRP) reinforcements under monotonically increasing load on beams keeping constant load on columns is carried out in this study. Totally eighteen numbers of specimens are cast and tested for different parametric conditions like beam longitudinal reinforcement ratio, concrete strength, column reinforcement ratio, joint aspect ratio and influence of the joint stirrups at the joint. Also finite element analysis is performed to simulate the behaviour of the beam-column joints under various parametric conditions. Based on this study, a modified design equation is proposed for assessing the joint shear strength of the GFRP reinforced beam-column specimens based on the experimental results and the review of the prevailing design equations.

  1. Terahertz Light Source and User Area at FACET

    SciTech Connect

    Wu, Z.; Li, S.Z.; Litos, M.; Fisher, A.D.; Hogan, M.J.; /SLAC

    2011-11-08

    FACET at SLAC provides high charge, high peak current, low emittance electron beam that is bunched at THz wavelength scale during its normal operation. A THz light source based coherent transition radiation (CTR) from this beam would potentially be the brightest short-pulse THz source ever constructed. Efforts have been put into building this photon source together with a user area, to provide a platform to utilize this unique THz radiation for novel nonlinear and ultrafast phenomena researches and experiments. Being a long-time underutilized portion of the electromagnetic spectrum, terahertz (100 GHz {approx} 10 THz) spectral range is experiencing a renaissance in recent years, with broad interests from chemical and biological imaging, material science, telecommunication, semiconductor and superconductor research, etc. Nevertheless, the paucity of THz sources especially strong THz radiation hinders both its commercial applications and nonlinear processes research. FACET - Facilities for Accelerator science and Experimental Test beams at SLAC - provides 23 GeV electron beam with peak currents of {approx} 20 kA that can be focused down to 100 {mu}m{sup 2} transversely. Such an intense electron beam, when compressed to sub-picosecond longitudinal bunch length, coherently radiates high intensity EM fields well within THz frequency range that are orders of magnitude stronger than those available from laboratory tabletop THz sources, which will enable a wide variety of THz related research opportunities. Together with a description of the FACET beamline and electron beam parameters, this paper will report FACET THz radiation generation via coherent transition radiation and calculated photon yield and power spectrum. A user table is being set up along the THz radiation extraction sites, and equipped with various signal diagnostics including THz power detector, Michelson interferometer, sample stages, and sets of motorized optical components. This setup will also be

  2. Green synthesis of Pt-doped TiO2 nanocrystals with exposed (001) facets and mesoscopic void space for photo-splitting of water under solar irradiation

    NASA Astrophysics Data System (ADS)

    Banerjee, Biplab; Amoli, Vipin; Maurya, Abhayankar; Sinha, Anil Kumar; Bhaumik, Asim

    2015-06-01

    We report a non-trivial facile chemical approach using ionic liquid ([bmim][Cl]) as a porogen for the synthesis of (001) faceted TiO2 nanocrystals having mesoscopic void space. This faceted TiO2 nanomaterial has been doped with Pt nanoclusters through chemical impregnation. The resulting Pt-doped TiO2 nanomaterials are thoroughly characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), ultra high resolution transmission electron microscopy (UHR-TEM), energy dispersive X-ray spectrometry (EDX), UV-vis diffuse reflection spectroscopy (DRS) and N2 sorption studies. These Pt/TiO2 nanocrystals with (001) exposed facets are employed as efficient and benign catalysts for hydrogen production from pure water and methanol-water systems under one AM 1.5G sunlight illumination. The effect of platinum loading and methanol-water ratio on the photocatalytic activity of the faceted TiO2 nanocrystals are investigated and it is found that hydrogen evolution rates have been enhanced significantly upon Pt loading. Under optimized reaction conditions the highest photocatalytic activity of 11.2 mmol h-1 g-1 has been achieved over ca. 1.0 wt% Pt loaded Pt/TiO2 nanocrystals with (001) exposed facets, which is one of the highest hydrogen evolution rates over the noble metal/TiO2 system reported to date in the literature.We report a non-trivial facile chemical approach using ionic liquid ([bmim][Cl]) as a porogen for the synthesis of (001) faceted TiO2 nanocrystals having mesoscopic void space. This faceted TiO2 nanomaterial has been doped with Pt nanoclusters through chemical impregnation. The resulting Pt-doped TiO2 nanomaterials are thoroughly characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), ultra high resolution transmission electron microscopy (UHR-TEM), energy dispersive X-ray spectrometry (EDX), UV-vis diffuse reflection spectroscopy (DRS) and

  3. Seismic response of rock joints and jointed rock mass

    SciTech Connect

    Ghosh, A.; Hsiung, S.M.; Chowdhury, A.H.

    1996-06-01

    Long-term stability of emplacement drifts and potential near-field fluid flow resulting from coupled effects are among the concerns for safe disposal of high-level nuclear waste (HLW). A number of factors can induce drift instability or change the near-field flow patterns. Repetitive seismic loads from earthquakes and thermal loads generated by the decay of emplaced waste are two significant factors. One of two key technical uncertainties (KTU) that can potentially pose a high risk of noncompliance with the performance objectives of 10 CFR Part 60 is the prediction of thermal-mechanical (including repetitive seismic load) effects on stability of emplacement drifts and the engineered barrier system. The second KTU of concern is the prediction of thermal-mechanical-hydrological (including repetitive seismic load) effects on the host rock surrounding the engineered barrier system. The Rock Mechanics research project being conducted at the Center for Nuclear Waste Regulatory Analyses (CNWRA) is intended to address certain specific technical issues associated with these two KTUs. This research project has two major components: (i) seismic response of rock joints and a jointed rock mass and (ii) coupled thermal-mechanical-hydrological (TMH) response of a jointed rock mass surrounding the engineered barrier system (EBS). This final report summarizes the research activities concerned with the repetitive seismic load aspect of both these KTUs.

  4. Joint lubrication.

    PubMed

    McCutchen, C W

    1983-01-01

    The fine-pored, easily compressed articular cartilage provides animal joints with self-pressurized hydrostatic (weeping) lubrication. The solid skeletons of the cartilages press against each other, but so lightly that their rubbing is lubricated successfully by synovial fluid--a boundary lubricant too weak to lubricate ordinary bearings. PMID:6317095

  5. Chemical changes accompanying facet degradation of AlGaAs quantum well lasers

    NASA Astrophysics Data System (ADS)

    Houle, F. A.; Neiman, D. L.; Tang, W. C.; Rosen, H. J.

    1992-11-01

    Detailed measurements are reported using high-resolution scanning Auger microscopy of the chemical state of uncoated quantum well (QW) laser facets after brief and intermediate operating times. Analyses or uncoated facets which have suffered catastrophic optical damage (COD) under various operating conditions are described. The data show clearly that initial facet compositions are variable and far from ideal. After operation for as little as 2-10 min, the composition of the facet regions of the active/graded index and cladding layer change markedly, but no single type of change can be linked to COD. In particular, facet oxidation is not uniform or extensive, and facets which suffer COD are not necessarily more oxidized than those which have not. Composition changes are not limited to the facet surface, indicating that elemental redistribution during laser operation is very fast. These results suggest that the process of facet degradation plays a complex role in laser degradation.

  6. Passive Ball Capture Joint

    NASA Technical Reports Server (NTRS)

    Cloyd, Richard A. (Inventor); Bryan, Thomas C. (Inventor)

    2003-01-01

    A passive ball capture joint has a sleeve with a plurality of bores distributed about a circumference thereof and formed therethrough at an acute angle relative to the sleeve's longitudinal axis. A spring-loaded retainer is slidingly fitted in each bore and is biased such that, if allowed, will extend at least partially into the sleeve to retain a ball therein. A ring, rotatably mounted about the bores, has an interior wall defining a plurality of shaped races that bear against the spring-loaded retainers. A mechanized rotational force producer is coupled to the ring. The ring can be rotated from a first position (that presses the retainers into the sleeve to lock the ball in place) to a second position (that allows the retainers to springback out of the sleeve to release the ball).

  7. Observation of edge-facets in <100> InP crystals grown by LEC method

    NASA Astrophysics Data System (ADS)

    Shibata, Masatomo; Sasaki, Yukio; Inada, Tomoki; Kuma, Shoji

    1990-05-01

    The growth of edge-facets on <100> InP crystals has been investigated using microscopy. The solid/liquid interface in the region of edge-facets was found to have a knife-edged shape, while that of a region without facets had a smooth shape. The irregular patterns of edge-facets point to instability in the growth at the periphery of a crystal, and this instability is found to be related to the generation of twins.

  8. SOME RECENT IDEAS IN RESEARCH METHODOLOGY--FACET DESIGN AND THEORY OF DATA.

    ERIC Educational Resources Information Center

    RUNKEL, PHILIP J.

    FACET DESIGN, AS ORIGINATED BY LOUIS GUTTMAN, IS A METHOD OF SYSTEMATICALLY ORDERING A PROBLEM FOR RESEARCH. FACET ANALYSIS ENABLES THE VALIDITY OF AN ASSESSMENT OF THE ORDERING PROCESS TO BE TESTED. THE LOGIC OF FACET DESIGN AND ANALYSIS IS BASED UPON SYSTEMATIC DELINEATION OF THE IMPORTANT VARIABLES PRIOR TO DATA COLLECTION AND THE EVALUATION OF…

  9. Effects of joints in truss structures

    NASA Technical Reports Server (NTRS)

    Ikegami, R.

    1988-01-01

    The response of truss-type structures for future space applications, such as Large Deployable Reflector (LDR), will be directly affected by joint performance. Some of the objectives of research at BAC were to characterize structural joints, establish analytical approaches that incorporate joint characteristics, and experimentally establish the validity of the analytical approaches. The test approach to characterize joints for both erectable and deployable-type structures was based upon a Force State Mapping Technique. The approach pictorially shows how the nonlinear joint results can be used for equivalent linear analysis. Testing of the Space Station joints developed at LaRC (a hinged joint at 2 Hz and a clevis joint at 2 Hz) successfully revealed the nonlinear characteristics of the joints. The Space Station joints were effectively linear when loaded to plus or minus 500 pounds with a corresponding displacement of about plus or minus 0.0015 inch. It was indicated that good linear joints exist which are compatible with errected structures, but that difficulty may be encountered if nonlinear-type joints are incorporated in the structure.

  10. How Many Facets are Needed to Represent the Surface Energy Balance of an Urban Area?

    NASA Astrophysics Data System (ADS)

    Porson, Aurore; Harman, Ian N.; Bohnenstengel, Sylvia I.; Belcher, Stephen E.

    2009-07-01

    We investigate the question of how many facets are needed to represent the energy balance of an urban area by developing simplified 3-, 2- and 1-facet versions of a 4-facet energy balance model of two-dimensional streets and buildings. The 3-facet model simplifies the 4-facet model by averaging over the canyon orientation, which results in similar net shortwave and longwave balances for both wall facets, but maintains the asymmetry in the heat fluxes within the street canyon. For the 2-facet model, on the assumption that the wall and road temperatures are equal, the road and wall facets can be combined mathematically into a single street-canyon facet with effective values of the heat transfer coefficient, albedo, emissivity and thermodynamic properties, without further approximation. The 1-facet model requires the additional assumption that the roof temperature is also equal to the road and wall temperatures. Idealised simulations show that the geometry and material properties of the walls and road lead to a large heat capacity of the combined street canyon, whereas the roof behaves like a flat surface with low heat capacity. This means that the magnitude of the diurnal temperature variation of the street-canyon facets are broadly similar and much smaller than the diurnal temperature variation of the roof facets. Consequently, the approximation that the street-canyon facets have similar temperatures is sound, and the road and walls can be combined into a single facet. The roof behaves very differently and a separate roof facet is required. Consequently, the 2-facet model performs similarly to the 4-facet model, while the 1-facet model does not. The models are compared with previously published observations collected in Mexico City. Although the 3- and 2-facet models perform better than the 1-facet model, the present models are unable to represent the phase of the sensible heat flux. This result is consistent with previous model comparisons, and we argue that this

  11. Joint assembly

    NASA Technical Reports Server (NTRS)

    Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

    2010-01-01

    A joint assembly is provided which includes a drive assembly and a swivel mechanism. The drive assembly features a motor operatively associated with a plurality of drive shafts for driving auxiliary elements, and a plurality of swivel shafts for pivoting the drive assembly. The swivel mechanism engages the swivel shafts and has a fixable element that may be attached to a foundation. The swivel mechanism is adapted to cooperate with the swivel shafts to pivot the drive assembly with at least two degrees of freedom relative to the foundation. The joint assembly allows for all components to remain encased in a tight, compact, and sealed package, making it ideal for space, exploratory, and commercial applications.

  12. Facet-controlled {100}Rh-Pt and {100}Pt-Pt dendritic nanostructures by transferring the {100} facet nature of the core nanocube to the branch nanocubes

    NASA Astrophysics Data System (ADS)

    Khi, Nguyen Tien; Park, Jongsik; Baik, Hionsuck; Lee, Hyunkyung; Sohn, Jeong-Hun; Lee, Kwangyeol

    2015-02-01

    Facet-controlled dendritic nanostructures are expected to exhibit excellent catalytic properties because both aggregation-free nature and controlled facet-originated activity and selectivity can be accomplished. However, such examples are extremely rare due to the incompatibility of the dendrite formation process with the usage of surface-stabilizing moieties, which are typically used to control facets. Herein, we demonstrate that regiospecific growth on a facet-controlled core nanoparticle can induce the facet-control of the branch nanoparticles. Specifically, facet-controlled dendritic nanostructures of {100}Rh-Pt and {100}Pt-Pt can be conveniently prepared by transferring the crystallographic behaviour of the {100}Pt dendritic core nanocube to the {100}Rh or {100}Pt branch nanocubes.Facet-controlled dendritic nanostructures are expected to exhibit excellent catalytic properties because both aggregation-free nature and controlled facet-originated activity and selectivity can be accomplished. However, such examples are extremely rare due to the incompatibility of the dendrite formation process with the usage of surface-stabilizing moieties, which are typically used to control facets. Herein, we demonstrate that regiospecific growth on a facet-controlled core nanoparticle can induce the facet-control of the branch nanoparticles. Specifically, facet-controlled dendritic nanostructures of {100}Rh-Pt and {100}Pt-Pt can be conveniently prepared by transferring the crystallographic behaviour of the {100}Pt dendritic core nanocube to the {100}Rh or {100}Pt branch nanocubes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07049f

  13. Load cell

    DOEpatents

    Spletzer, Barry L.

    2001-01-01

    A load cell combines the outputs of a plurality of strain gauges to measure components of an applied load. Combination of strain gauge outputs allows measurement of any of six load components without requiring complex machining or mechanical linkages to isolate load components. An example six axis load cell produces six independent analog outputs which can be combined to determine any one of the six general load components.

  14. Load cell

    DOEpatents

    Spletzer, B.L.

    1998-12-15

    A load cell combines the outputs of a plurality of strain gauges to measure components of an applied load. Combination of strain gauge outputs allows measurement of any of six load components without requiring complex machining or mechanical linkages to isolate load components. An example six axis load cell produces six independent analog outputs, each directly proportional to one of the six general load components. 16 figs.

  15. Load cell

    DOEpatents

    Spletzer, Barry L.

    1998-01-01

    A load cell combines the outputs of a plurality of strain gauges to measure components of an applied load. Combination of strain gauge outputs allows measurement of any of six load components without requiring complex machining or mechanical linkages to isolate load components. An example six axis load cell produces six independent analog outputs, each directly proportional to one of the six general load components.

  16. The role of surface passivation in controlling Ge nanowire faceting

    DOE PAGESBeta

    Gamalski, A. D.; Tersoff, J.; Kodambaka, S.; Zakharov, D. N.; Ross, F. M.; Stach, E. A.

    2015-11-05

    In situ transmission electron microscopy observations of nanowire morphologies indicate that during Au-catalyzed Ge nanowire growth, Ge facets can rapidly form along the nanowire sidewalls when the source gas (here, digermane) flux is decreased or the temperature is increased. This sidewall faceting is accompanied by continuous catalyst loss as Au diffuses from the droplet to the wire surface. We suggest that high digermane flux and low temperatures promote effective surface passivation of Ge nanowires with H or other digermane fragments inhibiting diffusion and attachment of Au and Ge on the sidewalls. Furthermore, these results illustrate the essential roles of themore » precursor gas and substrate temperature in maintaining nanowire sidewall passivation, necessary to ensure the growth of straight, untapered, <111>-oriented nanowires.« less

  17. Arthroscopic Debridement of Pediatric Accessory Anterolateral Talar Facet Causing Impingement.

    PubMed

    Neumann, Julie A; Mannava, Sandeep; Gross, Christopher E; Wooster, Benjamin M; Busch, Michael T

    2016-04-01

    Symptomatic subfibular and/or lateral talocalcaneal impingement in pediatric patients may result from an accessory anterolateral talar facet (AALTF). This impingement may cause pain and disability and may limit athletic performance in high-level athletes. We report the case of a 12-year-old female competitive gymnast who had refractory, lateral-sided right ankle pain for 4 months and underwent right ankle arthroscopic resection of the AALTF causing impingement. Standard medial and anterolateral portals with the addition of an accessory anterolateral-distal portal were used in conjunction with a 30° 2.7-mm-diameter arthroscope. The AALTF was resected with a combination of a shaver and a motorized rasp. Intraoperative fluoroscopy was used to verify successful debridement of the bony facet. This case illustrates that arthroscopic debridement is a technique to treat subfibular and/or talocalcaneal impingement associated with an AALTF. PMID:27462543

  18. Using Facet Clusters to Map Learner Modes of Reasoning

    NASA Astrophysics Data System (ADS)

    Vokos, Stamatis; DeWater, L. S.; Seeley, L.; Kraus, P.

    2006-12-01

    The Department of Physics and the School of Education at Seattle Pacific University, together with FACET Innovations, LLC, are beginning the second year of a five-year NSF TPC project, Improving the Effectiveness of Teacher Diagnostic Skills and Tools. We are working in partnership with school districts in Washington State to use formative assessment as a means to helping teachers and precollege students deepen their understanding of foundational topics in physical science. We utilize a theoretical framework of knowledge-in-pieces to identify and categorize widespread productive and unproductive modes of reasoning in the topical areas of Properties of Matter, Heat and Temperature, and Physical and Chemical Changes. In this talk, we describe the development and iterative refinement of certain facet clusters of student ideas, as well as the usefulness and limitations of such a mapping scheme. * Supported in part by NSF grant #ESI-0455796, The Boeing Corporation, and the SPU Science Initiative.

  19. The role of surface passivation in controlling Ge nanowire faceting

    SciTech Connect

    Gamalski, A. D.; Tersoff, J.; Kodambaka, S.; Zakharov, D. N.; Ross, F. M.; Stach, E. A.

    2015-11-05

    In situ transmission electron microscopy observations of nanowire morphologies indicate that during Au-catalyzed Ge nanowire growth, Ge facets can rapidly form along the nanowire sidewalls when the source gas (here, digermane) flux is decreased or the temperature is increased. This sidewall faceting is accompanied by continuous catalyst loss as Au diffuses from the droplet to the wire surface. We suggest that high digermane flux and low temperatures promote effective surface passivation of Ge nanowires with H or other digermane fragments inhibiting diffusion and attachment of Au and Ge on the sidewalls. Furthermore, these results illustrate the essential roles of the precursor gas and substrate temperature in maintaining nanowire sidewall passivation, necessary to ensure the growth of straight, untapered, <111>-oriented nanowires.

  20. Faceting and commensurability in crystal structures of colloidal thin films.

    PubMed

    Ramiro-Manzano, F; Meseguer, F; Bonet, E; Rodriguez, I

    2006-07-14

    This Letter investigates the influence of finite size effects on the particle arrangement of thin film colloidal crystals. A rich variety of crystallographic faceting with large single domain microcrystallites is shown. Optical reflectance experiments together with scanning electron microscopy permit the identification of the crystal symmetry and the facet orientation, as well as the exact number of monolayers. When the cell thickness is not commensurable with a high symmetry layering, particles arrange themselves in a periodic distribution of (111)- and (100)-orientated face centered cubic (fcc) microcrystallites separated by planar defects. These structures can be described as a fcc ordering orientated along a vicinal surface, modified by a periodic distribution of fcc (111) stacking faults. PMID:16907485

  1. Nonjudging Facet of Mindfulness Predicts Enhanced Smoking Cessation in Hispanics

    PubMed Central

    Spears, Claire Adams; Houchins, Sean C.; Stewart, Diana W.; Chen, Minxing; Correa-Fernández, Virmarie; Cano, Miguel Ángel; Heppner, Whitney L.; Vidrine, Jennifer I.; Wetter, David W.

    2015-01-01

    Although most smokers express interest in quitting, actual quit rates are low. Identifying strategies to enhance smoking cessation is critical, particularly among underserved populations including Hispanics, for whom many of the leading causes of death are related to smoking. Mindfulness (purposeful, non-judgmental attention to the present moment) has been linked to increased likelihood of cessation. Given that mindfulness is multifaceted, determining which aspects of mindfulness predict cessation could help to inform interventions. This study examined whether facets of mindfulness predict cessation in 199 Spanish-speaking smokers of Mexican heritage (63.3% male, mean age=39, 77.9% ≤ high school education) receiving smoking cessation treatment. Primary outcomes were 7-day abstinence at weeks 3 and 26 post-quit (biochemically-confirmed and determined using an intent-to-treat approach). Logistic random coefficients regression models were utilized to examine the relationship between mindfulness facets and abstinence over time. Independent variables were subscales of the Five Facet Mindfulness Questionnaire (Observing, Describing, Acting with Awareness, Nonjudging, Nonreactivity). The Nonjudging subscale (i.e., accepting thoughts and feelings without evaluating them) uniquely predicted better odds of abstinence up to 26 weeks post-quit. This is the first known study to examine whether specific facets of mindfulness predict smoking cessation. The ability to experience thoughts, emotions, and withdrawal symptoms without judging them may be critical in the process of quitting smoking. Results indicate potential benefits of mindfulness among smokers of Mexican heritage and suggest that smoking cessation interventions might be enhanced by central focus on the Nonjudging aspect of mindfulness. PMID:25961148

  2. Extraversion and psychopathology: A facet-level analysis.

    PubMed

    Watson, David; Stasik, Sara M; Ellickson-Larew, Stephanie; Stanton, Kasey

    2015-05-01

    The goal of this study was to explicate how the lower order facets of extraversion are related to psychopathology. We used a "bottom-up" approach in which specific extraversion scales from 3 comprehensive personality inventories were used to model these facets as latent factors. We collected both self-report and interview measures of a broad range of psychopathology from a large community sample. Replicating previous findings using a similar approach (Naragon-Gainey & Watson, 2014; Naragon-Gainey, Watson, & Markon, 2009), structural analyses yielded four factors: Positive Emotionality, Sociability, Assertiveness, and Experience Seeking. Scores on these latent dimensions were related to psychopathology in correlational analyses and in two sets of regressions (the first series used the four facets as predictors; the second included composite scores on the other Big Five domains as additional predictors). These results revealed a striking level of specificity. As predicted, Positive Emotionality displayed especially strong negative links to depressive symptoms and diagnoses. Sociability also was negatively related to psychopathology, showing particularly strong associations with indicators of social dysfunction and the negative symptoms of schizotypy (i.e., social anxiety, social aloofness, and restricted affectivity). Assertiveness generally had weak associations at the bivariate level but was negatively related to social anxiety and was positively correlated with some forms of externalizing. Finally, Experience Seeking had substantial positive associations with a broad range of indicators related to externalizing and bipolar disorder; it also displayed negative links to agoraphobia. These differential correlates demonstrate the importance of examining personality-psychopathology relations at the specific facet level. PMID:25751628

  3. Effect of Solder Joint Length on Fracture Under Bending

    NASA Astrophysics Data System (ADS)

    Akbari, Saeed; Nourani, Amir; Spelt, Jan K.

    2016-01-01

    Fracture tests were conducted on copper-solder-copper joints of various lengths using double-cantilever-beam (DCB) specimens under mode I loading conditions. The thickness and length of the solder joints were large enough to neglect any anisotropy associated with the solder microstructure. It was found that the critical strain energy release rate at crack initiation, G ci, was insensitive to the length of the solder joint; however, for joints shorter than a characteristic length which was a function of the thickness and the mechanical properties of the solder layer and the substrates, the fracture load increased with increasing solder joint length. A sandwich model was developed for the analysis of the stress and strain in solder joints, taking into account the influence of both the bending deformation and the shear deformation of the substrates on the solder joint stresses. Consistent with the experimental results, it was found that solder joints longer than the characteristic length have a maximum peel stress that remains unchanged with joint length, causing the joint strength to become independent of the joint length. A closed-form analytical solution was developed for the characteristic length of DCB specimens under mode I loading. The experimental results were in good agreement with the analytical model and with finite element results. The generality of the G ci failure criterion was demonstrated by comparing the experimental results and the fracture load predictions of mode I DCB solder joints with different lengths.

  4. Selective Facet Reactivity During Cation Exchange in Cadmium Sulfide Nanorods

    SciTech Connect

    Sadtler, Bryce; Demchenko, Denis; Zheng, Haimei; Hughes, Steven; Merkle, Maxwell; Dahmen, Ulrich; Wang, Lin-Wang; Alivisatos, A. Paul

    2008-12-18

    The partial transformation of ionic nanocrystals through cation exchange has been used to synthesize nanocrystal heterostructures. We demonstrate that the selectivity for cation exchange to take place at different facets of the nanocrystal plays an important role in determining the resulting morphology of the binary heterostructure. In the case of copper I (Cu+) cation exchange in cadmium sulfide (CdS) nanorods, the reaction starts preferentially at the ends of the nanorods such that copper sulfide (Cu2S) grows inwards from either end. The resulting morphology is very different from the striped pattern obtained in our previous studies of silver I (Ag+) exchange in CdS nanorods where non-selective nucleation of silver sulfide (Ag2S) occurs. From interface formation energies calculated for several models of epitaxialconnections between CdS and Cu2S or Ag2S, we infer the relative stability of each interface during the nucleation and growth of Cu2S or Ag2S within the CdS nanorods. The epitaxial connections of Cu2S to the end facets of CdS nanorods minimize the formation energy, making these interfaces stable throughout the exchange reaction. However, as the two end facets of wurtzite CdS nanorods are crystallographically nonequivalent, asymmetric heterostructures can be produced.

  5. The Chernyshenko Conscientiousness Scales: A New Facet Measure of Conscientiousness.

    PubMed

    Green, Jessica A; O'Connor, Daryl B; Gartland, Nicola; Roberts, Brent W

    2016-06-01

    The current research sought to validate the Chernyshenko Conscientiousness Scales (CCS), a novel measure designed to assess six facets of conscientiousness. Data from 7,569 U.S. participants and 649 U.K. participants were analyzed to assess the internal reliability and factorial structure of the scales. Test-retest reliability, convergent and divergent validity, and criterion-related validity were also evaluated using a separate U.K. sample (n = 118; n = 80 for test-retest). The results showed that those items designed to measure industriousness, order, self-control, traditionalism, and virtue were best represented by a five-factor structure, broadly consistent with the five scales. However, the content and structure of the responsibility scale requires further investigation. Overall, the CCS has the potential to be a useful alternative to the faceted measures of conscientiousness that are currently available. However, future research is required to refine a number of problematic items and to clarify which facets can be better described as interstitial dimensions between conscientiousness and other Big Five domains. PMID:25903479

  6. SHIFT: a distributed runoff model using irregular triangular facets*1

    NASA Astrophysics Data System (ADS)

    Palacios-Vélez, Oscar Luis; Cuevas-Renaud, Baltasar

    1992-06-01

    SHIFT (Sistema HIdrológico de Facetas Triangulares) is a computational system that allows for the: (1) creation, editing and visualization of a watershed Digital Elevation Model (DEM), based on the Triangular Irregular Network (TIN) concepts; (2) input and interpolation of soil, river-bed, and rainfall data; and (3) calculation and routing of runoff in all the facets and reaches. The TIN DEM model is constructed from a set of points, where the slope changes abruptly. Afterwards, the drainage network is automatically identified and an interactive editor allows the addition or deletion of points to eliminate network discontinuities. Rainfall data are interpolated by means of a procedure based on the minimization of the bending energy of a thin plate. In order to calculate and route the runoff, the system determines the routing sequence of river segments and for each one: identifies the facets forming the contributing area; and determines a cascade of overland flow planes. Then, for each element and time interval, the system calculates the infiltration and routes the resultant runoff by a numerical solution of the kinematic wave equations. This information is saved and the user can see the hydrograph for any facet or reach.

  7. Facets of loneliness and depression among Chinese children and adolescents.

    PubMed

    Lau, S; Chan, D W; Lau, P S

    1999-12-01

    The authors examined the relation among different facets of loneliness and depression in a sample of 6,356 Chinese children and adolescents from Grades 4-9. Loneliness and depression were closely related among the primary (Grades 4-6) and secondary (Grades 7-9) students, both boys and girls. Although the different facets of loneliness were predictive of the various facets of depression, peer-related loneliness and aloneness were more predictive of depression in both groups than was parent-related loneliness. The students in Grades 5 and 6 scored lower for loneliness but a little higher for depression than did the students in Grade 4. The students in Grades 8 and 9 scored higher than the students in Grade 7 for loneliness and depression. The primary boys scored higher than the primary girls for both loneliness and depression. Among the secondary students, there was no difference between the scores of the boys and those of the girls for loneliness, but the boys scored lower than the girls for depression. PMID:10646306

  8. Tunable plasmonic nanoparticles with catalytically active high-index facets.

    PubMed

    Jing, Hao; Zhang, Qingfeng; Large, Nicolas; Yu, Chunmei; Blom, Douglas A; Nordlander, Peter; Wang, Hui

    2014-06-11

    Noble metal nanoparticles have been of tremendous interest due to their intriguing size- and shape-dependent plasmonic and catalytic properties. Combining tunable plasmon resonances with superior catalytic activities on the same metallic nanoparticle, however, has long been challenging because nanoplasmonics and nanocatalysis typically require nanoparticles in two drastically different size regimes. Here, we demonstrate that creation of high-index facets on subwavelength metallic nanoparticles provides a unique approach to the integration of desired plasmonic and catalytic properties on the same nanoparticle. Through site-selective surface etching of metallic nanocuboids whose surfaces are dominated by low-index facets, we have controllably fabricated nanorice and nanodumbbell particles, which exhibit drastically enhanced catalytic activities arising from the catalytically active high-index facets abundant on the particle surfaces. The nanorice and nanodumbbell particles also possess appealing tunable plasmonic properties that allow us to gain quantitative insights into nanoparticle-catalyzed reactions with unprecedented sensitivity and detail through time-resolved plasmon-enhanced spectroscopic measurements. PMID:24842375

  9. Tunable Plasmonic Nanoparticles with Catalytically Active High-Index Facets

    NASA Astrophysics Data System (ADS)

    Jing, Hao; Large, Nicolas; Zhang, Qinfeng; Nordlander, Peter; Wang, Hui

    2015-03-01

    Noble metal nanoparticles have been of tremendous interest due to their intriguing size- and shape-dependent plasmonic and catalytic properties. Combining tunable plasmon resonances with superior catalytic activities on the same metallic nanoparticle, however, has long been challenging because nanoplasmonics and nanocatalysis typically require nanoparticles in two drastically different size regimes. Here, we demonstrate that creation of high-index facets on subwavelength metallic nanoparticles provides a unique approach to the integration of desired plasmonic and catalytic properties on the same nanoparticle. Through site-selective surface etching of metallic nanocuboids whose surfaces are dominated by low-index facets, we have controllably fabricated nanorice and nanodumbbell shaped particles, which exhibit drastically enhanced catalytic activities arising from the catalytically active high-index facets abundant on the particle surfaces. The nanorice and nanodumbbell particles also possess appealing tunable plasmonic properties that allow us to gain quantitative insights into nanoparticle-catalyzed reactions with unprecedented sensitivity and detail through time-resolved plasmon-enhanced spectroscopic measurements. Past affiliation: Rice University.

  10. A Reduced Order, One Dimensional Model of Joint Response

    SciTech Connect

    DOHNER,JEFFREY L.

    2000-11-06

    As a joint is loaded, the tangent stiffness of the joint reduces due to slip at interfaces. This stiffness reduction continues until the direction of the applied load is reversed or the total interface slips. Total interface slippage in joints is called macro-slip. For joints not undergoing macro-slip, when load reversal occurs the tangent stiffness immediately rebounds to its maximum value. This occurs due to stiction effects at the interface. Thus, for periodic loads, a softening and rebound hardening cycle is produced which defines a hysteretic, energy absorbing trajectory. For many jointed sub-structures, this hysteretic trajectory can be approximated using simple polynomial representations. This allows for complex joint substructures to be represented using simple non-linear models. In this paper a simple one dimensional model is discussed.

  11. Scarf Joints of Composite Materials: Testing and Analysis

    NASA Astrophysics Data System (ADS)

    Kwon, Y. W.; Marrón, A.

    2009-12-01

    The objective of this study is to develop a reliable computational model in order to investigate joint strengths of scarf joint configurations constructed from carbon-fiber and glass-fiber woven fabric laminates with different material combinations like glass/glass, glass/carbon, carbon/glass, and carbon/carbon under various loading conditions such as axial, bending moment and shear loading. Both experimental and computational studies are conducted. For the experimental study, specimens made of hybrid scarf joints using carbon-fiber and glass-fiber woven fabrics are tested under compressive loadings to determine their joint failure strengths. Computational models are then developed using the discrete resin layer model along with fracture mechanics and virtual crack closure techniques. The numerical models are validated against the experimental data. The validate models are used to predict the joint strengths under different loading conditions such as axial, shear, and bending moment loadings.

  12. Prosthetic elbow joint

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce C. (Inventor)

    1994-01-01

    An artificial, manually positionable elbow joint for use in an upper extremity, above-elbow, prosthetic is described. The prosthesis provides a locking feature that is easily controlled by the wearer. The instant elbow joint is very strong and durable enough to withstand the repeated heavy loadings encountered by a wearer who works in an industrial, construction, farming, or similar environment. The elbow joint of the present invention comprises a turntable, a frame, a forearm, and a locking assembly. The frame generally includes a housing for the locking assembly and two protruding ears. The forearm includes an elongated beam having a cup-shaped cylindrical member at one end and a locking wheel having a plurality of holes along a circular arc on its other end with a central bore for pivotal attachment to the protruding ears of the frame. The locking assembly includes a collar having a central opening with a plurality of internal grooves, a plurality of internal cam members each having a chamfered surface at one end and a V-shaped slot at its other end; an elongated locking pin having a crown wheel with cam surfaces and locking lugs secured thereto; two coiled compression springs; and a flexible filament attached to one end of the elongated locking pin and extending from the locking assembly for extending and retracting the locking pin into the holes in the locking wheel to permit selective adjustment of the forearm relative to the frame. In use, the turntable is affixed to the upper arm part of the prosthetic in the conventional manner, and the cup-shaped cylindrical member on one end of the forearm is affixed to the forearm piece of the prosthetic in the conventional manner. The elbow joint is easily adjusted and locked between maximum flex and extended positions.

  13. Life Estimation of Hip Joint Prosthesis

    NASA Astrophysics Data System (ADS)

    Desai, C.; Hirani, H.; Chawla, A.

    2014-11-01

    Hip joint is one of the largest weight-bearing structures in the human body. In the event of a failure of the natural hip joint, it is replaced with an artificial hip joint, known as hip joint prosthesis. The design of hip joint prosthesis must be such so as to resist fatigue failure of hip joint stem as well as bone cement, and minimize wear caused by sliding present between its head and socket. In the present paper an attempt is made to consider both fatigue and wear effects simultaneously in estimating functional-life of the hip joint prosthesis. The finite element modeling of hip joint prosthesis using HyperMesh™ (version 9) has been reported. The static analysis (load due to the dead weight of the body) and dynamic analysis (load due to walking cycle) have been described. Fatigue life is estimated by using the S-N curve of individual materials. To account for progressive wear of hip joint prosthesis, Archard's wear law, modifications in socket geometry and dynamic analysis have been used in a sequential manner. Using such sequential programming reduction in peak stress has been observed with increase in wear. Finally life is estimated on the basis of socket wear.

  14. A new shoulder model with a biologically inspired glenohumeral joint.

    PubMed

    Quental, C; Folgado, J; Ambrósio, J; Monteiro, J

    2016-09-01

    Kinematically unconstrained biomechanical models of the glenohumeral (GH) joint are needed to study the GH joint function, especially the mechanisms of joint stability. The purpose of this study is to develop a large-scale multibody model of the upper limb that simulates the 6 degrees of freedom (DOF) of the GH joint and to propose a novel inverse dynamics procedure that allows the evaluation of not only the muscle and joint reaction forces of the upper limb but also the GH joint translations. The biomechanical model developed is composed of 7 rigid bodies, constrained by 6 anatomical joints, and acted upon by 21 muscles. The GH joint is described as a spherical joint with clearance. Assuming that the GH joint translates according to the muscle load distribution, the redundant muscle load sharing problem is formulated considering as design variables the 3 translational coordinates associated with the GH joint translations, the joint reaction forces associated with the remaining kinematic constraints, and the muscle activations. For the abduction motion in the frontal plane analysed, the muscle and joint reaction forces estimated by the new biomechanical model proposed are similar to those estimated by a model in which the GH joint is modeled as an ideal spherical joint. Even though this result supports the assumption of an ideal GH joint to study the muscle load sharing problem, only a 6 DOF model of the GH joint, as the one proposed here, provides information regarding the joint translations. In this study, the biomechanical model developed predicts an initial upward and posterior migration of the humeral head, followed by an inferior and anterior movement, which is in good agreement with the literature. PMID:27381499

  15. Room Temperature and Elevated Temperature Composite Sandwich Joint Testing

    NASA Technical Reports Server (NTRS)

    Walker, Sandra P.

    1998-01-01

    Testing of composite sandwich joint elements has been completed to verify the strength capacity of joints designed to carry specified running loads representative of a high speed civil transport wing. Static tension testing at both room and an elevated temperature of 350 F and fatigue testing at room temperature were conducted to determine strength capacity, fatigue life, and failure modes. Static tension test results yielded failure loads above the design loads for the room temperature tests, confirming the ability of the joint concepts tested to carry their design loads. However, strength reductions as large as 30% were observed at the elevated test temperature, where all failure loads were below the room temperature design loads for the specific joint designs tested. Fatigue testing resulted in lower than predicted fatigue lives.

  16. Guideline for bolted joint design and analysis : version 1.0.

    SciTech Connect

    Brown, Kevin H.; Morrow, Charles W.; Durbin, Samuel; Baca, Allen

    2008-01-01

    This document provides general guidance for the design and analysis of bolted joint connections. An overview of the current methods used to analyze bolted joint connections is given. Several methods for the design and analysis of bolted joint connections are presented. Guidance is provided for general bolted joint design, computation of preload uncertainty and preload loss, and the calculation of the bolted joint factor of safety. Axial loads, shear loads, thermal loads, and thread tear out are used in factor of safety calculations. Additionally, limited guidance is provided for fatigue considerations. An overview of an associated Mathcad{copyright} Worksheet containing all bolted joint design formulae presented is also provided.

  17. Taming a Beast of Burden--On Some Issues with the Conceptualisation and Operationalisation of Cognitive Load

    ERIC Educational Resources Information Center

    Beckmann, Jens F.

    2010-01-01

    Research on cognitive load theory (CLT) has not yet provided facet-specific measures of cognitive load. The lack of valid methods to measure intrinsic, extraneous and germane cognitive load makes it difficult to empirically test theoretical explanations of effects caused by manipulations of instructional designs. This situation also imposes…

  18. Non-invasive Loading Model of Murine Osteoarthritis.

    PubMed

    Poulet, Blandine

    2016-07-01

    Osteoarthritis is the commonest degenerative joint disease, leading to joint pain and disability. The mouse has been the primary animal used for research, due to its size, relatively short lifespan, and the availability of genetically modified animals. Importantly, they show pathogenesis similar to osteoarthritis in humans. Mechanical loading is a major risk factor for osteoarthritis, and various mouse models have been developed to study the role and effects of mechanics on health and disease in various joints. This review describes the main mouse models used to non-invasively apply mechanical loads on joints. Most of the mouse models of osteoarthritis target the knee, including repetitive loading and joint injury such as ligament rupture, but a few studies have also characterised models for elbow, temporomandibular joint, and whole-body vibration spinal loading. These models are a great opportunity to dissect the influences of various types of mechanical input on joint health and disease. PMID:27177901

  19. A chemical bath deposition route to facet-controlled Ag3PO4 thin films with improved visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Gunjakar, Jayavant L.; Jo, Yun Kyung; Kim, In Young; Lee, Jang Mee; Patil, Sharad B.; Pyun, Jae.-Chul.; Hwang, Seong-Ju

    2016-08-01

    A facile, economic, and reproducible chemical bath deposition (CBD) method is developed for the fabrication of facet-controlled Ag3PO4 thin films with enhanced visible light photocatalytic activity. The fine-control of bath temperature, precursor, complexing agent, substrate, and solution pH is fairly crucial in preparing the facet-selective thin film of Ag3PO4 nanocrystal. The change of precursor from silver nitrate to silver acetate makes possible the tailoring of the crystal shape of Ag3PO4 from cube to rhombic dodecahedron and also the bandgap tuning of the deposited films. The control of [Ag+]/[phosphate] ratio enables to maximize the loading amount of Ag3PO4 crystals per the unit area of the deposited film. All the fabricated Ag3PO4 thin films show high photocatalytic activity for visible light-induced degradation of organic molecules, which can be optimized by tailoring the crystal shape of the deposited crystals. This CBD method is also useful in preparing the facet-controlled hybrid film of Ag3PO4-ZnO photocatalyst. The present study clearly demonstrates the usefulness of the present CBD method for fabricating facet-controlled thin films of metal oxosalt and its nanohybrid.

  20. [The bionic artificial joint capsule study (1)--mechanics simulation].

    PubMed

    Su, Shihu; Zhang, Jianhua; Tao, Dehua

    2007-02-01

    In this paper, a three-dimensional finite element analysis (FEA) model was created for bionic artificial joint with joint capsule. Finite element method (FEM) was used to calculate and simulate mechanics distribution of the joint capsule under different thickness of the joint capsule, different loading, and different angular displacements. The results of the simulation show that the maximum stress is created in the joint area between artificial joint capsule. And the effect of the thickness of the artificial joint capsule on the stress magnitude and distribution is depend on motion model. On standing situation, the maximum stress decreases with the increase of the thickness of joint capsule. However, on walking situation, the maximum stress increases with the increase of the thickness of joint capsule. Whatever conditions simulated, the maximum stress of the artificial joint capsule is not over the limit of the material strength (9.97 megapascals). All the large stress, which gained from the simulation under different situations, locates at the interface between the capsule and the artificial joint. This is because the artificial joint and the capsule transfer loading each other at the interface. At the same time, supporting area of the capsule at the location of the interface is minimum for the whole vesicle. The stress concentration is inevitable at the interface due to the model structure. This result will offer guidance for the optimum joint structure of the capsule and the artificial joint. PMID:17333904

  1. Facet-selective charge carrier transport, deactivation mechanism and stabilization of a Cu2O photo-electro-catalyst.

    PubMed

    Li, Yang; Yun, Xiaogang; Chen, Hong; Zhang, Wenqin; Li, Yongdan

    2016-03-14

    A facet-dependent photo-deactivation mechanism of Cu2O was verified and reported, which is caused by the facet-dependent charge carrier transport. During irradiation, the {100} and {110} crystal facets are selectively corroded by the photo-generated holes, while the {111} facets are comparatively stable. PMID:26898270

  2. Oxygen-induced nano-faceting of Re(11 2 bar 1)

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Chen, Wenhua; Bartynski, Robert A.

    2015-05-01

    We report results from a detailed study of oxygen-induced faceting of Re(11 2 bar 1) using low energy electron diffraction (LEED). Depending on conditions for reaction with oxygen, the initially planar Re(11 2 bar 1) surface evolves sequentially to form zigzag chains consisting of (01 1 bar 0) and (10 1 bar 0) facets that coexist with stepped (11 2 bar 1) plateaus; three-sided pyramids exposing (01 1 bar 0), (10 1 bar 0) and (33 6 bar 4) facets; a faceted surface with five facets including (01 1 bar 0), (10 1 bar 0), (11 2 bar 2)-(2 × 1), (01 1 bar 1)-(2 × 1) and (10 1 bar 1)-(2 × 1); and four-sided pyramids exposing { 01 1 bar 0} and { 01 1 bar 1}-(2 × 1) facets. We have observed reversible morphological transitions between the faceted surfaces and discovered that each intermediate facet in the evolutionary chain contains microscopic structural elements of the preceding and following facets, which may provide a natural explanation for the microscopic mass transport pathways in the morphological evolution. Scanning tunneling microscopy (STM) data confirm the morphology of faceted surfaces and give complementary information to LEED results.

  3. Crystal facet effect on structural stability and electronic properties of wurtzite InP nanowires

    NASA Astrophysics Data System (ADS)

    Yang, Xiaodong; Shu, Haibo; Jin, Mengting; Liang, Pei; Cao, Dan; Li, Can; Chen, Xiaoshuang

    2014-06-01

    The crystal-facet effect on the structural stability and electronic properties of wurtzite InP nanowires (NWs) with different side-facets are investigated by using first-principles calculation within density-function theory. The surface-energy calculation suggests that side-facet structures of InP NWs are unreconstructed due to the fact that the low-index {11¯00} and {112¯0} facets with paired In-P dimers satisfy the electron counting rule. The calculated formation energies indicate that the structural stability of InP NWs strongly depends on their side-facets. Among considered InP NWs with different side-facets, the {11¯00} faceted NWs present the highest stability due to the relative low surface atom ratio, which is in good agreement with experimental observations where wurtzite InP NWs prefer to be surrounded by {11¯00} facets. The size dependence of NW band gap indicates that the band gap (Eg) of uniform-sized InP NWs with different side-facets follows the trend, Eg -{112¯0} > Eg -{11¯00}-{112¯0} > Eg -{11¯00}, when NW diameter is larger than 3 nm and a reverse trend is found in the smaller sized NWs (d < 3 nm). Our result opens the possibility to engineer the band gap of wurtzite InP NWs by controlling their side-facets.

  4. [An assistant artificial hip joint].

    PubMed

    Shi, Zhen-man; Chen, Jian-chang; Shi, Jiang; Chen, Wenhong; Zhang, Chunhao

    2002-01-01

    The assistant artificial hip joint (AAHJ) is a new impermanent hip support implanted in the body. It is used for treatment of ischemic necrosis of the femoral head at the early stage. It reserves the natural femoral head, increases its containment and decreases its load, thus makes the recovery of the necrosed femoral head. The AAHJ's moving axis center is the same as that of the femoral head. Therefore, the moving range of the hip joint is very close to the normal postoperatively. The patient can walk with loading in 3 weeks after the surgical operation, and can regain his (or her) daily work and life in 2 to 3 months of the operation. The AAHJ's structure is simple and the price is cheap. PMID:16104164

  5. Status of Plasma Electron Hose Instability Studies in FACET

    SciTech Connect

    Adli, Erik; England, Robert Joel; Frederico, Joel; Hogan, Mark; Li, Selina Zhao; Litos, Michael Dennis; Nosochkov, Yuri; An, Weiming; Mori, Warren; /UCLA

    2011-12-13

    In the FACET plasma-wakefield acceleration experiment a dense 23 GeV electron beam will interact with lithium and cesium plasmas, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons may lead to a fast growing electron hose instability. By using optics dispersion knobs to induce a controlled z-x tilt along the beam entering the plasma, we investigate the transverse behavior of the beam in the plasma as function of the tilt. We seek to quantify limits on the instability in order to further explore potential limitations on future plasma wakefield accelerators due to the electron hose instability. The FACET plasma-wakefield experiment at SLAC will study beam driven plasma wakefield acceleration. A dense 23 GeV electron beam will interact with lithium or cesium plasma, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons drives the electron hose instability, as first studied by Whittum. While Ref. [2] indicates the possibility of a large instability growth rate for typical beam and plasma parameters, other studies including have shown that several physical effects may mitigate the hosing growth rate substantially. So far there has been no quantitative benchmarking of experimentally observed hosing in previous experiments. At FACET we aim to perform such benchmarking by for example inducing a controlled z-x tilt along the beamentering the plasma, and observing the transverse behavior of the beam in the plasma as function. The long-term objective of these studies is to quantify potential limitations on future plasma wakefield accelerators due to the electron hose instability.

  6. Sub-Facet Heterogeneity of the Urban Surface Energy Budget

    NASA Astrophysics Data System (ADS)

    Ramamurthy, P.; Bou-Zeid, E.; Smith, J. A.; Baeck, M. L.; Welty, C.

    2013-12-01

    The Princeton Urban Canopy Model (PUCM) and observational data are combined to understand the influence of urban sub-facet heterogeneity, and the associated influence of material properties, on the urban surface energy budget. This heterogeneity is related to the different surfaces and materials (asphalt, concrete, grass, black roofs, green roofs, etc.) that are typically found within one urban facet (roof, wall, and ground). Of particular interest is the role of water storage and evaporation from urban surfaces in modulating the energy budget. The PUCM is evaluated at sites of various urban densities. Subsequently, one densely-built site is selected for in-depth analysis and the model is applied, with sub-facet resolution, to simulate the water and energy budgets. Our analyses show that while all built surfaces convert most of the incoming energy into sensible rather than latent heat, sensible heat fluxes from asphalt and non-reflective rooftops are twice as high as those from concrete surfaces and light colored roofs. Another important and commonly observed characteristic of urban areas- the shift in peak time of sensible heat compared to rural areas, is shown to be mainly linked to concrete's high heat storage capacity. Our results also indicate that while evaporation from built surfaces is discontinuous and intermittent, overall, these surfaces accounted for nearly 16% of latent heat fluxes (LE) at the study site during the study period. More importantly, this contribution is mainly concentrated during the 48 hours following a rain event and thus its accurate representation is critical to our understanding of the urban surface energy budget during wet periods.

  7. Fully Crystalline Faceted Fe-Au Core-Shell Nanoparticles.

    PubMed

    Langlois, C; Benzo, P; Arenal, R; Benoit, M; Nicolai, J; Combe, N; Ponchet, A; Casanove, M J

    2015-08-12

    Fe-Au core-shell nanoparticles displaying an original polyhedral morphology have been successfully synthesized through a physical route. Analyses using transmission electron microscopy show that the Au shell forms truncated pyramids epitaxially grown on the (100) facets of the iron cubic core. The evolution of the elastic energy and strain field in the nanoparticles as a function of their geometry and composition is calculated using the finite-element method. The stability of the remarkable centered core-shell morphology experimentally observed is attributed to the weak elastic energy resulting from the low misfit at the Fe/Au (100) interface compared to the surface energy contribution. PMID:26146846

  8. An Enhanced Facet Determination Scheme in 3D

    NASA Astrophysics Data System (ADS)

    Reivinen, M.; Salonen, E.-M.; Todoshchenko, I.; Vaskelainen, V. P.

    2016-07-01

    An enhanced scheme for the determination of equilibrium crystal shapes is introduced. The emphasis of the present study is put on the proper detection of the facets appearing on the crystal surface. The original formulation presented in [1] employs the principle of the virtual work, and the enhanced scheme additionally makes use of a penalty formulation approach. The derivation of the penalty terms is discussed in detail. Finally, the corresponding discrete method is applied to a certain problematic example case presented in [1] resulting now in the correct crystal shape.

  9. Using Facet Clusters to Guide Teacher Professional Development

    NASA Astrophysics Data System (ADS)

    Seeley, Lane; DeWater, L. S.; Vokos, S.; Kraus, P.

    2006-12-01

    The Department of Physics and the School of Education at Seattle Pacific University, together with FACET Innovations, LLC, are beginning the second year of a five-year NSF TPC project, Improving the Effectiveness of Teacher Diagnostic Skills and Tools. We are working in partnership with school districts in Washington State to help teachers make their classrooms into better diagnostic learning environments. In this talk, we describe initial efforts to construct content-rich professional development courses for teachers, which are infused with diagnostic assessment that target the fine structure of student ideas in specific topical areas. * Supported in part by NSF grant #ESI-0455796, The Boeing Corporation, and the SPU Science Initiative.

  10. Model for reflection and transmission matrices of nanowire end facets

    NASA Astrophysics Data System (ADS)

    Svendsen, Guro K.; Weman, Helge; Skaar, Johannes

    2011-05-01

    Nanowires show a large potential for various electro-optical devices, such as light emitting diodes, solar cells, and nanowire lasers. We present a method developed to calculate the modal reflection and transmission matrix at the end facets of a waveguide of arbitrary cross-section, resulting in a generalized version of the Fresnel equations. The reflection can be conveniently computed using fast Fourier transforms once the waveguide modes are known. We demonstrate that the reflection coefficient is qualitatively described by two main parameters: the modal field confinement and the average Fresnel reflection of the plane waves constituting the waveguide mode.

  11. Composite Load Model Evaluation

    SciTech Connect

    Lu, Ning; Qiao, Hong

    2007-09-30

    The WECC load modeling task force has dedicated its effort in the past few years to develop a composite load model that can represent behaviors of different end-user components. The modeling structure of the composite load model is recommended by the WECC load modeling task force. GE Energy has implemented this composite load model with a new function CMPLDW in its power system simulation software package, PSLF. For the last several years, Bonneville Power Administration (BPA) has taken the lead and collaborated with GE Energy to develop the new composite load model. Pacific Northwest National Laboratory (PNNL) and BPA joint force and conducted the evaluation of the CMPLDW and test its parameter settings to make sure that: • the model initializes properly, • all the parameter settings are functioning, and • the simulation results are as expected. The PNNL effort focused on testing the CMPLDW in a 4-bus system. An exhaustive testing on each parameter setting has been performed to guarantee each setting works. This report is a summary of the PNNL testing results and conclusions.

  12. Modeling of joints for the dynamic analysis of truss structures

    NASA Technical Reports Server (NTRS)

    Belvin, W. Keith

    1987-01-01

    An experimentally-based method for determining the stiffness and damping of truss joints is described. The analytical models use springs and both viscous and friction dampers to simulate joint load-deflection behavior. A least-squares algorithm is developed to identify the stiffness and damping coefficients of the analytical joint models from test data. The effects of nonlinear joint stiffness such as joint dead band are also studied. Equations for predicting the sensitivity of beam deformations to changes in joint stiffness are derived and used to show the level of joint stiffness required for nearly rigid joint behavior. Finally, the global frequency sensitivity of a truss structure to random perturbations in joint stiffness is discussed.

  13. Suspended Load

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The suspended load of rivers and streams consists of the sediments that are kept in the water column by the upward components of the flow velocity. Suspended load may be divided into cohesive and non-cohesive loads which are primarily discriminated by sediment particle size. Non-cohesive sediment ...

  14. Domains and facets: hierarchical personality assessment using the revised NEO personality inventory.

    PubMed

    Costa, P T; McCrae, R R

    1995-02-01

    Personality traits are organized hierarchically, with narrow, specific traits combining to define broad, global factors. The Revised NEO Personality Inventory (NEO-PI-R; Costa & McCrae, 1992c) assesses personality at both levels, with six specific facet scales in each of five broad domains. This article describes conceptual issues in specifying facets of a domain and reports evidence on the validity of NEO-PI-R facet scales. Facet analysis-the interpretation of a scale in terms of the specific facets with which it correlates-is illustrated using alternative measures of the five-factor model and occupational scales. Finally, the hierarchical interpretation of personality profiles is discussed. Interpretation on the domain level yields a rapid understanding of the individual interpretation of specific facet scales gives a more detailed assessment. PMID:16367732

  15. Smooth and vertical facet formation for AlGaN-based deep-UV laser diodes.

    SciTech Connect

    Bogart, Katherine Huderle Andersen; Shul, Randy John; Stevens, Jeffrey; Banas, Michael Anthony; Crawford, Mary Hagerott; Allerman, Andrew Alan; Cross, Karen Charlene; Miller, Mary A.

    2008-10-01

    Using a two-step method of plasma and wet chemical etching, we demonstrate smooth, vertical facets for use in Al{sub x} Ga{sub 1-x} N-based deep-ultraviolet laser-diode heterostructures where x = 0 to 0.5. Optimization of plasma-etching conditions included increasing both temperature and radiofrequency (RF) power to achieve a facet angle of 5 deg from vertical. Subsequent etching in AZ400K developer was investigated to reduce the facet surface roughness and improve facet verticality. The resulting combined processes produced improved facet sidewalls with an average angle of 0.7 deg from vertical and less than 2-nm root-mean-square (RMS) roughness, yielding an estimated reflectivity greater than 95% of that of a perfectly smooth and vertical facet.

  16. Facility for Advanced Accelerator Experimental Tests (FACET) at SLAC and its Radiological Considerations

    SciTech Connect

    Mao, X.S.; Leitner, M.Santana; Vollaire, J.

    2011-08-22

    Facility for Advanced Accelerator Experimental Tests (FACET) in SLAC will be used to study plasma wakefield acceleration. FLUKA Monte Carlo code was used to design a maze wall to separate FACET project and LCLS project to allow persons working in FACET side during LCLS operation. Also FLUKA Monte Carlo code was used to design the shielding for FACET dump to get optimum design for shielding both prompt and residual doses, as well as reducing environmental impact. FACET will be an experimental facility that provides short, intense pulses of electrons and positrons to excite plasma wakefields and study a variety of critical issues associated with plasma wakefield acceleration [1]. This paper describes the FACET beam parameters, the lay-out and its radiological issues.

  17. Zernike-like systems in polygons and polygonal facets.

    PubMed

    Ferreira, Chelo; López, José L; Navarro, Rafael; Sinusía, Ester Pérez

    2015-07-20

    Zernike polynomials are commonly used to represent the wavefront phase on circular optical apertures, since they form a complete and orthonormal basis on the unit disk. In [Opt. Lett.32, 74 (2007)10.1364/OL.32.000074OPLEDP0146-9592] we introduced a new Zernike basis for elliptic and annular optical apertures based on an appropriate diffeomorphism between the unit disk and the ellipse and the annulus. Here, we present a generalization of this Zernike basis for a variety of important optical apertures, paying special attention to polygons and the polygonal facets present in segmented mirror telescopes. On the contrary to ad hoc solutions, most of them based on the Gram-Smith orthonormalization method, here we consider a piecewise diffeomorphism that transforms the unit disk into the polygon under consideration. We use this mapping to define a Zernike-like orthonormal system over the polygon. We also consider ensembles of polygonal facets that are essential in the design of segmented mirror telescopes. This generalization, based on in-plane warping of the basis functions, provides a unique solution, and what is more important, it guarantees a reasonable level of invariance of the mathematical properties and the physical meaning of the initial basis functions. Both the general form and the explicit expressions for a typical example of telescope optical aperture are provided. PMID:26367845

  18. Numerical computations of faceted pattern formation in snow crystal growth.

    PubMed

    Barrett, John W; Garcke, Harald; Nürnberg, Robert

    2012-07-01

    Faceted growth of snow crystals leads to a rich diversity of forms with remarkable sixfold symmetry. Snow crystal structures result from diffusion-limited crystal growth in the presence of anisotropic surface energy and anisotropic attachment kinetics. It is by now well understood that the morphological stability of ice crystals strongly depends on supersaturation, crystal size, and temperature. Until very recently it was very difficult to perform numerical simulations of this highly anisotropic crystal growth. In particular, obtaining facet growth in combination with dendritic branching is a challenging task. We present numerical simulations of snow crystal growth in two and three spacial dimensions using a computational method recently introduced by the present authors. We present both qualitative and quantitative computations. In particular, a linear relationship between tip velocity and supersaturation is observed. In our computations, surface energy effects, although small, have a pronounced effect on crystal growth. We compute solid plates, solid prisms, hollow columns, needles, dendrites, capped columns, and scrolls on plates. Although all these forms appear in nature, it is a significant challenge to reproduce them with the help of numerical simulations for a continuum model. PMID:23005427

  19. Intensity Effects of the FACET Beam in the SLAC Linac

    SciTech Connect

    Decker, F.-J.; Lipkowitz, N.; Sheppard, J.; White, G.R.; Wienands, U.; Woodley, M.; Yocky, G.; /SLAC

    2012-07-03

    The beam for FACET (Facility for Advanced aCcelerator Experimental Tests) at SLAC requires an energy-time correlation ('chirp') along the linac, so it can be compressed in two chicanes, one at the midpoint in sector 10 and one W-shaped chicane just before the FACET experimental area. The induced correlation has the opposite sign to the typical used for BNS damping, and therefore any orbit variations away from the center kick the tail of the beam more than the head, causing a shear in the beam and emittance growth. Any dispersion created along the linac has similar effects due to the high (>1.2% rms) energy spread necessary for compression. The initial huge emittances could be reduced by a factor of 10, but were still bigger than expected by a factor of 2-3. Normalized emittance of 3 {micro}m-rad in Sector 2 blew up to 150 {micro}m-rad in Sector 11 but could be reduced to about 6-12 {micro}m-rad, for the vertical plane although the results were not very stable. Investigating possible root causes for this, we found locations where up to 10 mm dispersion was created along the linac, which were finally verified with strong steering and up to 7 mm settling of the linac accelerator at these locations.

  20. Modification of flux profiles using a faceted concentrator

    SciTech Connect

    Lewandowski, A.; Scholl, K.; Bingham, C.

    1993-01-01

    The use of a faceted solar concentrator allows for some flexibility in aiming strategy and in the intensity of the resulting flux profile at the target. This can be an advantage when considering applications that do not necessarily require maximum concentration, particularly emerging, new applications in solar processed advanced materials. This paper will describe both an analysis of predicted flux profiles for several different aiming strategies using the SOLFUR computer code and experiments to characterize the actual flux profiles realized with a selected aiming strategy. The SOLFUR code models each of the furnace components explicitly. Aim points for each facet can be specified. Thus many strategies for adjusting aim points can be easily explored. One strategy calls for creating as uniform a flux over as large an area as possible. We explored this strategy analytically and experimentally. The experimental data consist of flux maps generated by a video imaging system calibrated against absolute flux measurements taken with circular foil calorimeters. Results from the analytical study and a comparison with the experimental data indicate that uniform profiles can be produced over fairly large areas.

  1. Interactive exploration of implicit and explicit relations in faceted datasets.

    PubMed

    Zhao, Jian; Collins, Christopher; Chevalier, Fanny; Balakrishnan, Ravin

    2013-12-01

    Many datasets, such as scientific literature collections, contain multiple heterogeneous facets which derive implicit relations, as well as explicit relational references between data items. The exploration of this data is challenging not only because of large data scales but also the complexity of resource structures and semantics. In this paper, we present PivotSlice, an interactive visualization technique which provides efficient faceted browsing as well as flexible capabilities to discover data relationships. With the metaphor of direct manipulation, PivotSlice allows the user to visually and logically construct a series of dynamic queries over the data, based on a multi-focus and multi-scale tabular view that subdivides the entire dataset into several meaningful parts with customized semantics. PivotSlice further facilitates the visual exploration and sensemaking process through features including live search and integration of online data, graphical interaction histories and smoothly animated visual state transitions. We evaluated PivotSlice through a qualitative lab study with university researchers and report the findings from our observations and interviews. We also demonstrate the effectiveness of PivotSlice using a scenario of exploring a repository of information visualization literature. PMID:24051774

  2. Numerical computations of faceted pattern formation in snow crystal growth

    NASA Astrophysics Data System (ADS)

    Barrett, John W.; Garcke, Harald; Nürnberg, Robert

    2012-07-01

    Faceted growth of snow crystals leads to a rich diversity of forms with remarkable sixfold symmetry. Snow crystal structures result from diffusion-limited crystal growth in the presence of anisotropic surface energy and anisotropic attachment kinetics. It is by now well understood that the morphological stability of ice crystals strongly depends on supersaturation, crystal size, and temperature. Until very recently it was very difficult to perform numerical simulations of this highly anisotropic crystal growth. In particular, obtaining facet growth in combination with dendritic branching is a challenging task. We present numerical simulations of snow crystal growth in two and three spacial dimensions using a computational method recently introduced by the present authors. We present both qualitative and quantitative computations. In particular, a linear relationship between tip velocity and supersaturation is observed. In our computations, surface energy effects, although small, have a pronounced effect on crystal growth. We compute solid plates, solid prisms, hollow columns, needles, dendrites, capped columns, and scrolls on plates. Although all these forms appear in nature, it is a significant challenge to reproduce them with the help of numerical simulations for a continuum model.

  3. A model for the geomorphic development of normal-fault facets

    NASA Astrophysics Data System (ADS)

    Tucker, G. E.; Hobley, D. E. J.; McCoy, S. W.

    2014-12-01

    Triangular facets are among the most striking landforms associated with normal faulting. The genesis of facets is of great interest both for the information facets contain about tectonic motion, and because the progressive emergence of facets makes them potential recorders of both geomorphic and tectonic history. In this report, we present observations of triangular facets in the western United States and in the Italian Central Apennines. Facets in these regions typically form quasi-planar surfaces that are aligned in series along and above the trace of an active fault. Some facet surfaces consist mainly of exposed bedrock, with a thin and highly discontinuous cover of loose regolith. Other facets are mantled by a several-decimeter-thick regolith cover. Over the course of its morphologic development, a facet slope segment may evolve from a steep (~60 degree) bedrock fault scarp, well above the angle of repose for soil, to a gentler (~20-40 degree) slope that can potentially sustain a coherent regolith cover. This evolutionary trajectory across the angle of repose renders nonlinear diffusion theory inapplicable. To formulate an alternative process-based theory for facet evolution, we use a particle-based approach that acknowledges the possibility for both short- and long-range sediment-grain motions, depending on the topography. The processes of rock weathering, grain entrainment, and grain motion are represented as stochastic state-pair transitions with specified transition rates. The model predicts that facet behavior can range smoothly along the spectrum from a weathering-limited mode to a transport-limited mode, depending on the ratio of fault-slip rate to bare-bedrock regolith production rate. The model also implies that facets formed along a fault with pinned tips should show systematic variation in slope angle that correlates with along-fault position and slip rate. Preliminary observations from central Italy and the eastern Basin and Range are consistent

  4. Testing composite-to-metal tubular lap joints

    NASA Astrophysics Data System (ADS)

    Guess, T. R.; Reedy, E. D., Jr.; Slavin, A. M.

    Procedures were developed to fabricate, nondestructively evaluate, and mechanically test composite-to-metal tubular joints. The axially loaded tubular lap joint specimen consisted of two metal tubes bonded within each end of a fiberglass composite tube. Joint specimens with both tapered and untapered aluminum adherends and a plain weave E-glass/epoxy composite were tested in tension, compression, and flexure. Other specimens with tapered and untapered steel adherends and a triaxially reinforced E-glass/epoxy composite were tested in tension and compression. Test results include joint strength and failure mode data. A finite element analysis of the axially loaded joints explains the effect of adherend geometry and material properties on measured joint strength. The flexural specimen was also analyzed; calculated surface strains are in good agreement with measured values, and joint failure occurs in the region of calculated peak peel stress.

  5. Effect of adhesive thickness on adhesively bonded T-joint

    NASA Astrophysics Data System (ADS)

    Abdullah, A. R.; Afendi, Mohd; Majid, M. S. Abdul

    2013-12-01

    The aim of this work is to analyze the effect of adhesive thickness on tensile strength of adhesively bonded stainless steel T-joint. Specimens were made from SUS 304 Stainless Steel plate and SUS 304 Stainless Steel perforated plate. Four T-joint specimens with different adhesive thicknesses (0.5, 1.0, 1.5 and 2.0 mm) were made. Experiment result shows T-joint specimen with adhesive thickness of 1.0 mm yield highest maximum load. Identical T-joint specimen jointed by spot welding was also tested. Tensile test shows welded T-Joint had eight times higher tensile load than adhesively bonded T-joint. However, in low pressure application such as urea granulator chamber, high tensile strength is not mandatory. This work is useful for designer in fertilizer industry and others who are searching for alternative to spot welding.

  6. Testing composite-to-metal tubular lap joints

    SciTech Connect

    Guess, T.R.; Reedy, E.D. Jr.; Slavin, A.M.

    1993-11-01

    Procedures were developed to fabricate, nondestructively evaluate, and mechanically test composite-to-metal tubular joints. The axially loaded tubular lap joint specimen consisted of two metal tubes bonded within each end of a fiberglass composite tube. Joint specimens with both tapered and untapered aluminum adherends and a plain weave E-glass/epoxy composite were tested in tension, compression, and flexure. Other specimens with tapered and untapered steel adherends and a triaxially reinforced E-glass/epoxy composite were tested in tension and compression. Test results include joint strength and failure mode data. A finite element analysis of the axially loaded joints explains the effect of adherend geometry and material properties on measured joint strength. The flexural specimen was also analyzed; calculated surface strains are in good agreement with measured values, and joint failure occurs in the region of calculated peak peel stress.

  7. Joint instability and osteoarthritis.

    PubMed

    Blalock, Darryl; Miller, Andrew; Tilley, Michael; Wang, Jinxi

    2015-01-01

    Joint instability creates a clinical and economic burden in the health care system. Injuries and disorders that directly damage the joint structure or lead to joint instability are highly associated with osteoarthritis (OA). Thus, understanding the physiology of joint stability and the mechanisms of joint instability-induced OA is of clinical significance. The first section of this review discusses the structure and function of major joint tissues, including periarticular muscles, which play a significant role in joint stability. Because the knee, ankle, and shoulder joints demonstrate a high incidence of ligament injury and joint instability, the second section summarizes the mechanisms of ligament injury-associated joint instability of these joints. The final section highlights the recent advances in the understanding of the mechanical and biological mechanisms of joint instability-induced OA. These advances may lead to new opportunities for clinical intervention in the prevention and early treatment of OA. PMID:25741184

  8. Joint x-ray

    MedlinePlus

    X-ray - joint; Arthrography; Arthrogram ... x-ray technologist will help you position the joint to be x-rayed on the table. Once in place, pictures are taken. The joint may be moved into other positions for more ...

  9. Joint Instability and Osteoarthritis

    PubMed Central

    Blalock, Darryl; Miller, Andrew; Tilley, Michael; Wang, Jinxi

    2015-01-01

    Joint instability creates a clinical and economic burden in the health care system. Injuries and disorders that directly damage the joint structure or lead to joint instability are highly associated with osteoarthritis (OA). Thus, understanding the physiology of joint stability and the mechanisms of joint instability-induced OA is of clinical significance. The first section of this review discusses the structure and function of major joint tissues, including periarticular muscles, which play a significant role in joint stability. Because the knee, ankle, and shoulder joints demonstrate a high incidence of ligament injury and joint instability, the second section summarizes the mechanisms of ligament injury-associated joint instability of these joints. The final section highlights the recent advances in the understanding of the mechanical and biological mechanisms of joint instability-induced OA. These advances may lead to new opportunities for clinical intervention in the prevention and early treatment of OA. PMID:25741184

  10. Anthropometric characteristics of wrists joint surfaces depending on lunate types.

    PubMed

    Dyankova, S

    2007-10-01

    It is well known that the lunate presents with two main types: lunate type I has one facet of its distal surface only for capitates, whereas lunate type II has two facets of the same surface for capitate and for hamate. Our previous anthropometric studies showed that the lunate type II wrists are of greater size than the lunate type I wrists. The aim of the present study was to determine whether the lunate types and the presence or absence of hamato-lunate joint correlate with anthropometric characteristics of the joint surfaces of other wrists. Sixteen sets of macerated wrists with the lunate type I and 21 with the lunate type II were studied. Two-thousand-four-hundred-and-forty-eight anthropometric measurements were done (for 68 anthropometric indicators) and 864 anthropometric indices were calculated (for 24 anthropometric indices) separately for the wrist joint surfaces. The absolute value of the anthropometric indicators of the joint surfaces of the separated wrists were greater in the wrists with the lunate type II, except for the indicators "Greatest length of the dorsal joint surface of pisiform", "Width of the proximal joint surface, measured in the middle" and "Greatest width of the proximal joint surface" for the trapezoid and "Greatest height of the ulnar joint surface" for the capitate. The enlargement of the joint surfaces for the scaphoid was mainly in proximo-distal direction. The enlargement for the triquetrum and pisiform was mainly in radio-ulnar direction. The enlargement for trapezium, trapezoid and capitate was mainly in dorso-volar direction (except for the ulnar joint surface of capitate). The enlargement for hamate was mainly in radio-ulnar and dorso-volar directions (except for the joint surfaces for capitate and triquetrum). The calculated indices illustrate the quantitative proportions of the variations mentioned above. The anthropometric differences are a good reason to make a clear distinction between both types of wrist joint

  11. Management of acromioclavicular joint injuries.

    PubMed

    Li, Xinning; Ma, Richard; Bedi, Asheesh; Dines, David M; Altchek, David W; Dines, Joshua S

    2014-01-01

    Acromioclavicular joint injuries are among the most common shoulder girdle injuries in athletes and most commonly result from a direct force to the acromion with the arm in an adducted position. Acromioclavicular joint injuries often present with associated injuries to the glenohumeral joint, including an increased incidence of superior labrum anterior posterior (SLAP) tears that may warrant further evaluation and treatment. Anteroposterior stability of the acromioclavicular joint is conferred by the capsule and acromioclavicular ligaments, of which the posterior and superior ligaments are the strongest. Superior-inferior stability is maintained by the coracoclavicular (conoid and trapezoid) ligaments. Type-I or type-II acromioclavicular joint injuries have been treated with sling immobilization, early shoulder motion, and physical therapy, with favorable outcomes. Return to activity can occur when normal shoulder motion and strength are obtained and the shoulder is asymptomatic as compared with the contralateral normal extremity. The management of type-III injuries remains controversial and is individualized. While a return to the previous level of functional activity with nonsurgical treatment has been documented in a number of case series, surgical reduction and coracoclavicular ligament reconstruction has been associated with a favorable outcome and can be considered in patients who place high functional demands on their shoulders or in athletes who participate in overhead sports. Surgical management is indicated for high-grade (≥type IV) acromioclavicular joint injuries to achieve anatomic reduction of the acromioclavicular joint, reconstruction of the coracoclavicular ligaments, and repair of the deltotrapezial fascia. Outcomes after surgical reconstruction of the coracoclavicular ligaments have been satisfactory with regard to achieving pain relief and return to functional activities, but further improvements in the biomechanical strength of these

  12. PRB rail loadings shatter record

    SciTech Connect

    Buchsbaum, L.

    2008-09-15

    Rail transport of coal in the Powder River Basin has expanded, with a record 2,197 trains loaded in a month. Arch Coal's Thunder basin mining complex has expanded by literally bridging the joint line railway. The dry fork mine has also celebrated its safety achievements. 4 photos.

  13. FACET: an object-oriented software framework for modeling complex social behavior patterns

    SciTech Connect

    Dolph, J. E.; Christiansen, J. H.; Sydelko, P. J.

    2000-06-30

    The Framework for Addressing Cooperative Extended Transactions (FACET) is a flexible, object-oriented architecture for implementing models of dynamic behavior of multiple individuals, or agents, in a simulation. These agents can be human (individuals or organizations) or animal and may exhibit any type of organized social behavior that can be logically articulated. FACET was developed by Argonne National Laboratory's (ANL) Decision and Information Sciences Division (DIS) out of the need to integrate societal processes into natural system simulations. The FACET architecture includes generic software components that provide the agents with various mechanisms for interaction, such as step sequencing and logic, resource management, conflict resolution, and preemptive event handling. FACET components provide a rich environment within which patterns of behavior can be captured in a highly expressive manner. Interactions among agents in FACET are represented by Course of Action (COA) object-based models. Each COA contains a directed graph of individual actions, which represents any known pattern of social behavior. The agents' behavior in a FACET COA, in turn, influences the natural landscape objects in a simulation (i.e., vegetation, soil, and habitat) by updating their states. The modular design of the FACET architecture provides the flexibility to create multiple and varied simulation scenarios by changing social behavior patterns, without disrupting the natural process models. This paper describes the FACET architecture and presents several examples of FACET models that have been developed to assess the effects of anthropogenic influences on the dynamics of the natural environment.

  14. Plasmas, Dielectrics and the Ultrafast: First Science and Operational Experience at FACET

    SciTech Connect

    Clarke, C.I.; Adli, E.; Corde, S.; Decker, F.J.; England, R.J.; Erickson, R.; Fisher, A.; Gessner, S.; Hast, C.; Hogan, M.J.; Li, S.Z.; Lipkowitz, N.; Litos, M.; Nosochkov, Y.; Seeman, J.; Sheppard, J.C.; Tudosa, I.; White, G.; Wienands, U.; Woodley, M.; Wu, Z.; /SLAC /UCLA

    2012-09-14

    FACET (Facility for Advanced Accelerator and Experimental Tests) is an accelerator R&D test facility that has been recently constructed at SLAC National Accelerator Laboratory. The facility provides 20 GeV, 3 nC electron beams, short (20 {micro}m) bunches and small (20 {micro}m wide) spot sizes, producing uniquely high power beams. FACET supports studies from many fields but in particular those of Plasma Wakefield Acceleration and Dielectric Wakefield Acceleration. FACET is also a source of THz radiation for material studies. We present the FACET design, initial operating experience and first science from the facility.

  15. Impact extractive fracture of jointed steel plates of a bolted joint

    NASA Astrophysics Data System (ADS)

    Daimaruya, M.; Fujiki, H.; Ambarita, H.

    2012-08-01

    This study is concerned with the development of a fracture criterion for the impact fracture of jointed steel plates of a bolted joint used in a car body. For the accurate prediction of crash characteristics of car bodies by computer-aided engineering (CAE), it is also necessary to examine the behavior and fracture of jointed steel plates subjected to impact loads. Although the actual impact fracture of jointed steel plates of a bolted joint used in cars is complicated, for simplifying the problem it might be classified into the shear fracture and the extractive fracture of jointed steel plates. Attention is given to the extractive fracture of jointed steel plates in this study. The extractive behavior and fracture of three kinds of steel plates used for cars are examined in experiments and numerical simulations. The impact extraction test of steel plates jointed by a bolt is performed using the one-bar method, together with the static test. In order to understand the mechanism of extractive fracture process of jointed steel plates, numerical simulations by a FEM code LS-DYNA are also carried out. The obtained results suggest that a stress-based fracture criterion may be developed for the impact extractive fracture of jointed steel plates of a bolted joint used in a car body.

  16. Spacesuit mobility knee joints

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C. (Inventor)

    1979-01-01

    Pressure suit mobility joints are for use in interconnecting adjacent segments of an hermetically sealed spacesuit in which low torques, low leakage and a high degree of reliability are required. Each of the joints is a special purpose joint characterized by substantially constant volume and low torque characteristics and includes linkages which restrain the joint from longitudinal distension and includes a flexible, substantially impermeable diaphragm of tubular configuration spanning the distance between pivotally supported annuli. The diaphragms of selected joints include rolling convolutions for balancing the joints, while various joints include wedge-shaped sections which enhance the range of motion for the joints.

  17. Spacesuit mobility joints

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C. (Inventor)

    1978-01-01

    Joints for use in interconnecting adjacent segments of an hermetically sealed spacesuit which have low torques, low leakage and a high degree of reliability are described. Each of the joints is a special purpose joint characterized by substantially constant volume and low torque characteristics. Linkages which restrain the joint from longitudinal distension and a flexible, substantially impermeable diaphragm of tubular configuration spanning the distance between pivotally supported annuli are featured. The diaphragms of selected joints include rolling convolutions for balancing the joints, while various joints include wedge-shaped sections which enhance the range of motion for the joints.

  18. Adaptive plasticity in mammalian masticatory joints

    NASA Astrophysics Data System (ADS)

    Ravosa, Matthew J.; Kunwar, Ravinder; Nicholson, Elisabeth K.; Klopp, Emily B.; Pinchoff, Jessie; Stock, Stuart R.; Stack, M. Sharon; Hamrick, Mark W.

    2006-08-01

    Genetically similar white rabbits raised on diets of different mechanical properties, as well as wild-type and myostatin-deficient mice raised on similar diets, were compared to assess the postweaning effects of elevated masticatory loads due to increased jaw-adductor muscle and bite forces on the proportions and properties of the mandibular symphysis and temporomandibular joint (TMJ). Microcomputed tomography (microCT) was used to quantify bone structure at a series of equidistant external and internal sites in coronal sections for a series of joint locations. Discriminant function analyses and non-parametric ANOVAs were used to characterize variation in biomineralization within and between loading cohorts. In both species, long-term excessive loading results in larger joint proportions, thicker articular and cortical bone, and increased biomineralization of hard tissues. Such adaptive plasticity appears designed to maintain the postnatal integrity of masticatory joint systems for a primary loading environment(s). This behavioral signal may be increasingly mitigated in older organisms by the interplay between adaptive and degradative joint tissue responses.

  19. Some new evidence on human joint lubrication.

    PubMed Central

    Unsworth, A; Dowson, D; Wright, V

    1975-01-01

    Theoretical consideration has been given to the use of pendulum machines which are used to examine the frictional properties of human joints by incorporating them as fulcra. As a result, a new type of pendulum machine has been built which incorporates the facility to apply sudden loads to the joint on starting the swinging motion, and also the ability to measure directly the frictional torque experienced by the joint. The results obtained from natural hip joints indicate the presence of squeeze film lubrication under conditions of sudden loading of a joint. In addition, a self-generated fluid film process was observed at low loads while at higher loads boundary lubrication appeared to be important. These results have been used to describe the lubrication regimens occurring in a normal activity such as walking. A single experiment carried out on a hip from a patient suffering from severe rheumatoid arthritis has also been reported and the frictional resistance was seen to be increased fifteenfold compared to a normal hip. Images PMID:1190847

  20. The analysis of adhesively bonded advanced composite joints using joint finite elements

    NASA Astrophysics Data System (ADS)

    Stapleton, Scott E.

    The design and sizing of adhesively bonded joints has always been a major bottleneck in the design of composite vehicles. Dense finite element (FE) meshes are required to capture the full behavior of a joint numerically, but these dense meshes are impractical in vehicle-scale models where a course mesh is more desirable to make quick assessments and comparisons of different joint geometries. Analytical models are often helpful in sizing, but difficulties arise in coupling these models with full-vehicle FE models. Therefore, a joint FE was created which can be used within structural FE models to make quick assessments of bonded composite joints. The shape functions of the joint FE were found by solving the governing equations for a structural model for a joint. By analytically determining the shape functions of the joint FE, the complex joint behavior can be captured with very few elements. This joint FE was modified and used to consider adhesives with functionally graded material properties to reduce the peel stress concentrations located near adherend discontinuities. Several practical concerns impede the actual use of such adhesives. These include increased manufacturing complications, alterations to the grading due to adhesive flow during manufacturing, and whether changing the loading conditions significantly impact the effectiveness of the grading. An analytical study is conducted to address these three concerns. Furthermore, proof-of-concept testing is conducted to show the potential advantages of functionally graded adhesives. In this study, grading is achieved by strategically placing glass beads within the adhesive layer at different densities along the joint. Furthermore, the capability to model non-linear adhesive constitutive behavior with large rotations was developed, and progressive failure of the adhesive was modeled by re-meshing the joint as the adhesive fails. Results predicted using the joint FE was compared with experimental results for various

  1. The Analysis of Adhesively Bonded Advanced Composite Joints Using Joint Finite Elements

    NASA Technical Reports Server (NTRS)

    Stapleton, Scott E.; Waas, Anthony M.

    2012-01-01

    The design and sizing of adhesively bonded joints has always been a major bottleneck in the design of composite vehicles. Dense finite element (FE) meshes are required to capture the full behavior of a joint numerically, but these dense meshes are impractical in vehicle-scale models where a course mesh is more desirable to make quick assessments and comparisons of different joint geometries. Analytical models are often helpful in sizing, but difficulties arise in coupling these models with full-vehicle FE models. Therefore, a joint FE was created which can be used within structural FE models to make quick assessments of bonded composite joints. The shape functions of the joint FE were found by solving the governing equations for a structural model for a joint. By analytically determining the shape functions of the joint FE, the complex joint behavior can be captured with very few elements. This joint FE was modified and used to consider adhesives with functionally graded material properties to reduce the peel stress concentrations located near adherend discontinuities. Several practical concerns impede the actual use of such adhesives. These include increased manufacturing complications, alterations to the grading due to adhesive flow during manufacturing, and whether changing the loading conditions significantly impact the effectiveness of the grading. An analytical study is conducted to address these three concerns. Furthermore, proof-of-concept testing is conducted to show the potential advantages of functionally graded adhesives. In this study, grading is achieved by strategically placing glass beads within the adhesive layer at different densities along the joint. Furthermore, the capability to model non-linear adhesive constitutive behavior with large rotations was developed, and progressive failure of the adhesive was modeled by re-meshing the joint as the adhesive fails. Results predicted using the joint FE was compared with experimental results for various

  2. A Novel Blasted and Grooved Low Profile Pedicle Screw Able to Resist High Compression Bending Loads

    PubMed Central

    Kim, Young-Sung; Choi, Hong-June; Kim, Kyung-Hyun; Park, Jeong-Yoon; Jeong, Hyun-Yong; Chin, Dong-Kyu; Kim, Keun-Su; Yoon, Young-Sul; Lee, Yoon-Chul; Cho, Yong-Eun

    2012-01-01

    Objective Polyaxial pedicle screws are a safe, useful adjunct to transpedicular fixation. However, the large screw head size can cause soft tissue irritation, high rod positioning, and facet joint injury. However, the mechanical resistance provided by small and low profile pedicle screws is very limited. We therefore developed a novel, low profile pedicle screw using grooving and blasting treatment that is able to resist a high compression bending load. Methods We evaluated the compression bending force to displacement and yield loads for seven different screw head types that differed with regard to their groove intervals and whether or not they had been blasted. Results The rank order of screw types that had the greatest compression bending force to displacement was as follows: (1) universal polyaxial, (2) low polyaxial with 0.1mm grooves and blasting, (3) low polyaxial with blasting, (4) low polyaxial with 0.15mm grooves and blasting, (5) low polyaxial with 0.05mm grooves and blasting, (6) low polyaxial with 0.05mm grooves, (7) and low polyaxial. Low polyaxial screws with 0.1mm grooves and blasting had the maximum yield load and highest compression bending force to displacement of all seven polyaxial screw head systems evaluated. Conclusion Blasting and grooving treatment of pedicle screw heads resulted in screw heads with a high yield load and compression bending force relative to displacement because of increased friction. Low polyaxial pedicle screws with 0.1 mm grooves treated by blasting have mechanical characteristics similar to those of universal polyaxial pedicle screws. PMID:25983790

  3. Aerodynamics Investigation of Faceted Airfoils at Low Reynolds Number

    NASA Astrophysics Data System (ADS)

    Napolillo, Zachary G.

    The desire and demand to fly farther and faster has progressively integrated the concept of optimization with airfoil design, resulting in increasingly complex numerical tools pursuing efficiency often at diminishing returns; while the costs and difficulty associated with fabrication increases with design complexity. Such efficiencies may often be necessary due to the power density limitations of certain aircraft such as small unmanned aerial vehicles (UAVs) and micro air vehicles (MAVs). This research, however, focuses on reducing the complexity of airfoils for applications where aerodynamic performance is less important than the efficiency of manufacturing; in this case a Hybrid Projectile. By employing faceted sections to approximate traditional contoured wing sections it may be possible to expedite manufacturing and reduce costs. We applied this method to the development of a low Reynolds number, disposable Hybrid Projectile requiring a 4.5:1 glide ratio, resulting in a series of airfoils which are geometric approximations to highly contoured cross-sections called ShopFoils. This series of airfoils both numerically and experimentally perform within a 10% margin of the SD6060 airfoil at low Re. Additionally, flow visualization has been conducted to qualitatively determine what mechanisms, if any, are responsible for the similarity in performance between the faceted ShopFoil sections and the SD6060. The data obtained by these experiments did not conclusively reveal how the faceted surfaces may influence low Re flow but did indicate that the ShopFoil s did not maintain flow attachment at higher angles of attack than the SD6060. Two reasons are provided for the unexpected performance of the ShopFoil: one is related to downwash effects, which are suspected of placing the outer portion of the span at an effective angle of attack where the ShopFoils outperform the SD6060; the other is the influence of the tip vortex on separation near the wing tips, which possibly

  4. Dynamic response of tunnels in jointed rocks

    SciTech Connect

    Heuze, F.E.; Shaffer, R.J.; Walton, O.R.; Maddix, D.M.

    1993-09-01

    The current proposed site for an underground nuclear waste repository is at Yucca Mountain, Nevada. The host rock is a jointed tuff. The question is: how will the repository behave under strong earthquake motion. The basic requirement for analysis is an ability to follow the dynamic motion of a multiplicity of discrete particles, i.e., rock blocks separated by joints and faults. The authors describe the application of the discrete element method (DEM) to the dynamic analysis of the response of tunnels in jointed rocks to earthquake loading. In situations where large motions of many blocks and collapse occur, the discontinuum-based DEM approach appears superior to other methods of analysis.

  5. Voyager: Exploratory Analysis via Faceted Browsing of Visualization Recommendations.

    PubMed

    Wongsuphasawat, Kanit; Moritz, Dominik; Anand, Anushka; Mackinlay, Jock; Howe, Bill; Heer, Jeffrey

    2016-01-01

    General visualization tools typically require manual specification of views: analysts must select data variables and then choose which transformations and visual encodings to apply. These decisions often involve both domain and visualization design expertise, and may impose a tedious specification process that impedes exploration. In this paper, we seek to complement manual chart construction with interactive navigation of a gallery of automatically-generated visualizations. We contribute Voyager, a mixed-initiative system that supports faceted browsing of recommended charts chosen according to statistical and perceptual measures. We describe Voyager's architecture, motivating design principles, and methods for generating and interacting with visualization recommendations. In a study comparing Voyager to a manual visualization specification tool, we find that Voyager facilitates exploration of previously unseen data and leads to increased data variable coverage. We then distill design implications for visualization tools, in particular the need to balance rapid exploration and targeted question-answering. PMID:26390469

  6. “Decoding” Angiogenesis: New Facets Controlling Endothelial Cell Behavior

    PubMed Central

    Sewduth, Raj; Santoro, Massimo M.

    2016-01-01

    Angiogenesis, the formation of new blood vessels, is a unique and crucial biological process occurring during both development and adulthood. A better understanding of the mechanisms that regulates such process is mandatory to intervene in pathophysiological conditions. Here we highlight some recent argument on new players that are critical in endothelial cells, by summarizing novel discoveries that regulate notorious vascular pathways such as Vascular Endothelial Growth Factor (VEGF), Notch and Planar Cell Polarity (PCP), and by discussing more recent findings that put metabolism, redox signaling and hemodynamic forces as novel unforeseen facets in angiogenesis. These new aspects, that critically regulate angiogenesis and vascular homeostasis in health and diseased, represent unforeseen new ground to develop anti-angiogenic therapies. PMID:27493632

  7. Giant photoluminescence emission in crystalline faceted Si grains

    PubMed Central

    Faraci, Giuseppe; Pennisi, Agata R.; Alberti, Alessandra; Ruggeri, Rosa; Mannino, Giovanni

    2013-01-01

    Empowering an indirect band-gap material like Si with optical functionalities, firstly light emission, represents a huge advancement constantly pursued in the realization of any integrated photonic device. We report the demonstration of giant photoluminescence (PL) emission by a newly synthesized material consisting of crystalline faceted Si grains (fg-Si), a hundred nanometer in size, assembled in a porous and columnar configuration, without any post processing. A laser beam with wavelength 632.8 nm locally produce such a high temperature, determined on layers of a given thickness by Raman spectra, to induce giant PL radiation emission. The optical gain reaches the highest value ever, 0.14 cm/W, representing an increase of 3 orders of magnitude with respect to comparable data recently obtained in nanocrystals. Giant emission has been obtained from fg-Si deposited either on glass or on flexible, low cost, polymeric substrate opening the possibility to fabricate new devices. PMID:24056300

  8. "Decoding" Angiogenesis: New Facets Controlling Endothelial Cell Behavior.

    PubMed

    Sewduth, Raj; Santoro, Massimo M

    2016-01-01

    Angiogenesis, the formation of new blood vessels, is a unique and crucial biological process occurring during both development and adulthood. A better understanding of the mechanisms that regulates such process is mandatory to intervene in pathophysiological conditions. Here we highlight some recent argument on new players that are critical in endothelial cells, by summarizing novel discoveries that regulate notorious vascular pathways such as Vascular Endothelial Growth Factor (VEGF), Notch and Planar Cell Polarity (PCP), and by discussing more recent findings that put metabolism, redox signaling and hemodynamic forces as novel unforeseen facets in angiogenesis. These new aspects, that critically regulate angiogenesis and vascular homeostasis in health and diseased, represent unforeseen new ground to develop anti-angiogenic therapies. PMID:27493632

  9. Do Different Facets of Impulsivity Predict Different Types of Aggression?

    PubMed Central

    Derefinko, Karen; DeWall, C. Nathan; Metze, Amanda V.; Walsh, Erin C.; Lynam, Donald R.

    2011-01-01

    The current study examined the relations between impulsivity-related traits (as assessed by the UPPS-P Impulsive Behavior Scale) and aggressive behaviors. Results indicated that UPPS-P Lack of Premeditation and Sensation Seeking were important in predicting general violence. In contrast, UPPS-P Urgency was most useful in predicting intimate partner violence. To further explore relations between intimate partner violence and Urgency, a measure of autonomic response to pleasant and aversive stimuli and facets of Neuroticism from the NEO PI-R were used as control variables. Autonomic responsivity was correlated with intimate partner violence at the zero-order level, and predicted significant variance in intimate partner violence in regression equations. However, UPPS-P Urgency was able to account for unique variance in intimate partner violence above and beyond measures of Neuroticism and arousal. Implications regarding the use of a multifaceted conceptualization of impulsivity in the prediction of different types of violent behavior are discussed. PMID:21259270

  10. Multi-faceted identities and interactions in mixed health teams.

    PubMed

    Arieli, Daniella; Hirschfeld, Miriam J

    2016-01-01

    The literature in the area of the health workforce and societies in conflict encompasses a wide range of studies and potential directions. Lately, Keshet and Popper-Giveon reported on a study based on interviews with 13 Arab Israeli nurses who work in Israeli hospitals. This preliminary study describes how being an Arab nurse in Israel is experienced and perceived by those nurses. The results indicate the need for further studies on the complexity of health workers' experiences in their changing and multi-faceted professional, cultural, gender and national identities. In order to manage health systems, in particular in divided societies that are characterized by inter-group conflicts, special attention should be given to studying the everyday processes in mixed teams. PMID:27441083

  11. Replicable Facets of Positive Emotionality and Their Relations to Psychopathology.

    PubMed

    Stanton, Kasey; Watson, David

    2015-12-01

    General individual differences in positive emotionality are negatively related to depression, social anxiety, and schizotypy/schizophrenia, and positively related to mania. However, the structure of positive emotionality remains unclear at the facet level, as there are significant disparities in the types of content assessed across emotionality measures. This study analyzed the lower order structure of positive emotionality in two samples, finding evidence for a replicable two-factor structure of Joviality and Experience Seeking. These factors demonstrated a markedly different pattern of relations in both direction and magnitude with internalizing, externalizing, and schizotypal symptoms. Joviality seems to represent an adaptive variant of positive emotionality, as it showed strong positive relations with well-being and moderate negative relations with measures of depression, social anxiety, and social anhedonia. In contrast, Experience Seeking appears to be somewhat maladaptive. It generally related positively to psychopathology, correlating most strongly with indicators of manic and externalizing symptoms. PMID:25260942

  12. Micro-Facet Scattering Model for Pulse Polarization Ranging

    NASA Astrophysics Data System (ADS)

    Stryjewski, J.; Roggemann, M.; Tyler, D.; Hand, D.

    Determining the shape, material and orientation of nano-sats (satellites too small to image from the ground) requires new sensing approaches. Pulse Polarization Ranging (PPR) is one such approach that uses the polarization and shape characteristics of laser pulses reflected from satellites to determine satellite shape, orientation and material. We use an innovative approach to relate PPR measurements to actual satellite characteristics (shape, material and orientation), requiring that we have an accurate physical and dynamical model of the satellite. In particular, to determine the polarization characteristics (depolarization, birefringence, diattenuation) of the reflected pulses we need an accurate model of light scattering from real (complex) surfaces. To do this, we have extended the micro-facet model of Ashikhmin et al. to include retro-reflection and multiple scattering effects. In this presentation, we describe the scattering model and its efficient implementation using graphical processing units (GPUs).

  13. Do different facets of impulsivity predict different types of aggression?

    PubMed

    Derefinko, Karen; DeWall, C Nathan; Metze, Amanda V; Walsh, Erin C; Lynam, Donald R

    2011-01-01

    This study examined the relations between impulsivity-related traits (as assessed by the UPPS-P Impulsive Behavior Scale) and aggressive behaviors. Results indicated that UPPS-P Lack of Premeditation and Sensation Seeking were important in predicting general violence. In contrast, UPPS-P Urgency was most useful in predicting intimate partner violence. To further explore relations between intimate partner violence and Urgency, a measure of autonomic response to pleasant and aversive stimuli and facets of Neuroticism from the NEO PI-R were used as control variables. Autonomic responsivity was correlated with intimate partner violence at the zero-order level, and predicted significant variance in intimate partner violence in regression equations. However, UPPS-P Urgency was able to account for unique variance in intimate partner violence, above and beyond measures of Neuroticism and arousal. Implications regarding the use of a multifaceted conceptualization of impulsivity in the prediction of different types of violent behavior are discussed. PMID:21259270

  14. Weldability aspects in the design and fabrication of aluminium structures subjected to fatigue loads. Part 1: Effect of welding on the structural integrity of joint types designed for repairing aluminium ship sections

    NASA Astrophysics Data System (ADS)

    Nevasmaa, P.; Peltonen, J.; Kuitunen, R.; Rahka, K.

    1993-05-01

    The Laboratory of Production Engineering and the Metals Laboratory of the Technical Research Center of Finland (VTT) have participated in a Nordic research project entitled 'New methods for joining of aluminium'. The results from Finnish work of the project will be presented in a report to be published in two parts. Part 1 of the report will evaluate the effects of welding on the structural integrity of some joint types primarily designed for repairing ship sections and sea crafts made from 6xxx (AlSiMg) series alloys.

  15. Variable loading roller

    DOEpatents

    Williams, D.M.

    1988-01-21

    An automatic loading roller for transmitting torque in traction drive devices in manipulator arm joints includes a two-part camming device having a first cam portion rotatable in place on a shaft by an input torque and a second cam portion coaxially rotatable and translatable having a rotating drive surface thereon for engaging the driven surface of an output roller with a resultant force proportional to the torque transmitted. Complementary helical grooves in the respective cam portions interconnected through ball bearings interacting with those grooves effect the rotation and translation of the second cam portion in response to rotation of the first. 14 figs.

  16. Variable loading roller

    DOEpatents

    Williams, Daniel M.

    1989-01-01

    An automatic loading roller for transmitting torque in traction drive devices in manipulator arm joints includes a two-part camming device having a first cam portion rotatable in place on a shaft by an input torque and a second cam portion coaxially rotatable and translatable having a rotating drive surface thereon for engaging the driven surface of an output roller with a resultant force proportional to the torque transmitted. Complementary helical grooves on the respective cam portions interconnected through ball bearings interacting with those grooves effect the rotation and translation of the second cam portion in response to rotation of the first.

  17. Bifactor analysis and construct validity of the five facet mindfulness questionnaire (FFMQ) in non-clinical Spanish samples

    PubMed Central

    Aguado, Jaume; Luciano, Juan V.; Cebolla, Ausias; Serrano-Blanco, Antoni; Soler, Joaquim; García-Campayo, Javier

    2015-01-01

    The objective of the present study was to examine the dimensionality, reliability, and construct validity of the Five Facet Mindfulness Questionnaire (FFMQ) in three Spanish samples using structural equation modeling (SEM). Pooling the FFMQ data from 3 Spanish samples (n = 1191), we estimated the fit of two competing models (correlated five-factor vs. bifactor) via confirmatory factor analysis. The factorial invariance of the best fitting model across meditative practice was also addressed. The pattern of relationships between the FFMQ latent dimensions and anxiety, depression, and distress was analyzed using SEM. FFMQ reliability was examined by computing the omega and omega hierarchical coefficients. The bifactor model, which accounted for the covariance among FFMQ items with regard to one general factor (mindfulness) and five orthogonal factors (observing, describing, acting with awareness, non-judgment, and non-reactivity), fit the FFMQ structure better than the correlated five-factor model. The relationships between the latent variables and their manifest indicators were not invariant across the meditative experience. Observing items had significant loadings on the general mindfulness factor, but only in the meditator sub-sample. The SEM analysis revealed significant links between mindfulness and symptoms of depression and stress. When the general factor was partialled out, the acting with awareness facet did not show adequate reliability. The FFMQ shows a robust bifactor structure among Spanish individuals. Nevertheless, the Observing subscale does not seem to be adequate for assessing mindfulness in individuals without meditative experience. PMID:25914664

  18. Joint fluid Gram stain

    MedlinePlus

    Gram stain of joint fluid ... A sample of joint fluid is needed. The fluid sample is sent to a lab where a small drop is placed in a ... on how to prepare for the removal of joint fluid, see joint fluid aspiration .

  19. Faceted phospholipid vesicles tailored for the delivery of Santolina insularis essential oil to the skin.

    PubMed

    Castangia, Ines; Manca, Maria Letizia; Caddeo, Carla; Maxia, Andrea; Murgia, Sergio; Pons, Ramon; Demurtas, Davide; Pando, Daniel; Falconieri, Danilo; Peris, José E; Fadda, Anna Maria; Manconi, Maria

    2015-08-01

    The aim of this work was to formulate Santolina insularis essential oil-loaded nanocarriers, namely Penetration Enhancer containing Vesicles (PEVs), evaluate the physico-chemical features and stability, and gain insights into their ability to deliver the oil to the skin. S. insularis essential oil was obtained by steam distillation, and was predominantly composed of terpenes, the most abundant being β-phellandrene (22.6%), myrcene (11.4%) and curcumenes (12.1%). Vesicles were prepared using phosphatidylcholine, and ethylene or propylene glycol were added to the water phase (10% (v/v)) to improve vesicle performances as delivery systems. Vesicles were deeply characterized by light scattering, cryogenic transmission electron microscopy and small/wide-angle X-ray scattering, the results showing polyhedral, faceted, unilamellar vesicles of ∼115 nm in size. The presence of the glycols improved vesicle stability under accelerated ageing conditions, without changes in size or migration phenomena (e.g. sedimentation and creaming). Confocal laser scanning microscopy images of pig skin treated with S. insularis formulations displayed a penetration ability of PEVs greater than that of control liposomes. Moreover, all formulations showed a marked in vitro biocompatibility in human keratinocytes. These findings suggest that the nanoformulation may be of value in enhancing the delivery of S. insularis essential oil to the skin, where it can exert its biological activities. PMID:26057243

  20. Hysteresis modeling of clamp band joint with macro-slip

    NASA Astrophysics Data System (ADS)

    Qin, Zhaoye; Cui, Delin; Yan, Shaoze; Chu, Fulei

    2016-01-01

    Clamp band joints are commonly used to connect spacecrafts with launch vehicles. Due to the frictional slippage between the joint components, hysteresis behavior might occur at joint interfaces under cyclic loading. The joint hysteresis will bring friction damping into the launching systems. In this paper, a closed-form hysteresis model for the clamp band joint is developed based on theoretical and numerical analyses of the interactions of the joint components. Then, the hysteresis model is applied to investigating the dynamic response of a payload fastened by the clamp band joint, where the nonlinearity and friction damping effects of the joint is evaluated. The proposed analytical model, which is validated by both finite element analyses and quasi-static experiments, has a simple form with sound accuracy and can be incorporated into the dynamic models of launching systems conveniently.