Effect of stress on energy flux deviation of ultrasonic waves in GR/EP composites

NASA Technical Reports Server (NTRS)

Prosser, William H.; Kriz, R. D.; Fitting, Dale W.

1990-01-01

Ultrasonic waves suffer energy flux deviation in graphite/epoxy because of the large anisotropy. The angle of deviation is a function of the elastic coefficients. For nonlinear solids, these coefficients and thus the angle of deviation is a function of stress. Acoustoelastic theory was used to model the effect of stress on flux deviation for unidirectional T300/5208 using previously measured elastic coefficients. Computations were made for uniaxial stress along the x3 axis (fiber axis) and the x1 for waves propagating in the x1x3 plane. These results predict a shift as large as three degrees for the quasi-transverse wave. The shift in energy flux offers a new nondestructive technique of evaluating stress in composites.

Clinical Evaluation of the Root Tear of the Posterior Horn of the Medial Meniscus in Total Knee Arthroplasty for Osteoarthritis.

PubMed

Choi, Eui-Sung; Park, Sang-Jun

2015-06-01

To investigate the incidence of root tears of the posterior horn of the medial meniscus in total knee replacement arthroplasty for knee osteoarthritis and retrospectively analyze clinical results and factors associated with root tears. There were 197 knees of 140 enrolled patients who had undergone total knee replacement arthroplasty between September 2010 and May 2014. The presence of a root tear of the posterior horn of the medial meniscus was confirmed in all patients. Statistical analysis was performed to investigate the correlation between root tears and the possible factors of meniscal tears including gender, age, severity of symptoms (visual analogue scale [VAS] score and medial joint line tenderness), grade of osteoarthritis (Kellgren-Lawrence grading scale), body mass index (BMI), varus deformity, and mechanical axis deviation. Meniscal tears were observed in 154 knees (78.17%). The root tear had correlation with the severity of osteoarthritis (p<0.05), varus deformity (p<0.05), mechanical axis deviation (p<0.05), and BMI (p<0.05). Factors considered to represent the severity of osteoarthritis were found to be associated with root tears of the medial meniscus posterior horn. Increased BMI seemed to be associated with the increased incidence of root tears of the medial meniscus posterior horn.

Flux pinning forces in irradiated a-axis oriented EuBa{sub 2}Cu{sub 3}O{sub 7} films

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

Martin, J. I.; Gonzalez, E. M.; Kwok, W.-K

1999-10-12

{alpha}-axis oriented EuBa{sub 2}Cu{sub 3}O{sub 7} films have been irradiated with high energy heavy ions in different configurations to study the possible pinning role of the artificial defects in this kind of samples. The original pinning limiting mechanism of the samples is not essentially altered what the irradiation is parallel to the CuO{sub 2} planes. However, when it is deviated from this direction, an increase in critical current density and a change in pinning force are observed when the magnetic field is parallel to the columnar defects at values around the matching field.

Multipole plasmons in graphene nanoellipses

NASA Astrophysics Data System (ADS)

Wang, Weihua; Song, Zhengyong

2018-02-01

We study multipole plasmons in graphene nanoellipses under the quasi-static approximation. The graphene is characterized by a homogeneous surface conductivity, and two coupled differential and integral equations are solved self-consistently to investigate the plasmonic modes in nanoellipses with a fixed area. With respect to the major axis, the symmetric and antisymmetric modes originally doubly degenerate in nanodisks will show different behavior as the semi-major axis increases. The eigen frequencies of the symmetric modes decrease, while those of the antisymmetric modes increase. At the edges, the phase changes of the symmetric dipole modes are linear and independent on structural changes; the phase changes of antisymmetric modes deviate from linear relationship, and the deviation depends on the semi-major axis. As a very large aspect ratio, they exhibit sharp peaks at the endpoints of the minor axis and zero phase changes at the endpoints of the major axis. The non-degenerate breathing mode shows its hot spots at the endpoints of the minor axis, and its eigen frequency gradually increases as the semi-major axis increases.

Do CAS measurements correlate with EOS 3D alignment measurements in primary TKA?

PubMed

Meijer, Marrigje F; Boerboom, Alexander L; Bulstra, Sjoerd K; Reininga, Inge H F; Stevens, Martin

2017-09-01

Objective of this study was to compare intraoperative computer-assisted surgery (CAS) alignment measurements during total knee arthroplasty (TKA) with pre- and postoperative coronal alignment measurements using EOS 3D reconstructions. In a prospective study, 56 TKAs using imageless CAS were performed and coronal alignment measurements were recorded twice: before bone cuts were made and after implantation of the prosthesis. Pre- and postoperative coronal alignment measurements were performed using EOS 3D reconstructions. Thanks to the EOS radiostereography system, measurement errors due to malpositioning and deformity during acquisition are eliminated. CAS measurements were compared with EOS 3D reconstructions. Varus/valgus angle (VV), mechanical lateral distal femoral angle (mLDFA) and mechanical medial proximal tibial angle (mMPTA) were measured. Significantly different VV angles were measured pre- and postoperatively with CAS compared to EOS. For preoperative measurements, mLDFA did not differ significantly, but a significantly larger mMPTA in valgus was measured with CAS. Results of this study indicate that differences in alignment measurements between CAS measurements and pre- and postoperative EOS 3D are due mainly to the difference between weight-bearing and non-weight-bearing position and potential errors in validity and reliability of the CAS system. EOS 3D measurements overestimate VV angle in lower limbs with substantial mechanical axis deviation. For lower limbs with minor mechanical axis deviation as well as for mMPTA measurements, CAS measures more valgus than EOS. Eventually the results of this study are of clinical relevance, since it raises concerns regarding the validity and reliability of CAS systems in TKA. IIb.

Patients with left bundle branch block and left axis deviation show a specific left ventricular asynchrony pattern: Implications for left ventricular lead placement during CRT implantation.

PubMed

Sciarra, Luigi; Golia, Paolo; Palamà, Zefferino; Scarà, Antonio; De Ruvo, Ermenegildo; Borrelli, Alessio; Martino, Anna Maria; Minati, Monia; Fagagnini, Alessandro; Tota, Claudia; De Luca, Lucia; Grieco, Domenico; Delise, Pietro; Calò, Leonardo

Left bundle branch block (LBBB) and left axis deviation (LAD) patients may have poor response to resynchronization therapy (CRT). We sought to assess if LBBB and LAD patients show a specific pattern of mechanical asynchrony. CRT candidates with non-ischemic cardiomyopathy and LBBB were categorized as having normal QRS axis (within -30° and +90°) or LAD (within -30° and -90°). Patients underwent tissue Doppler imaging (TDI) to measure time interval between onset of QRS complex and peak systolic velocity in ejection period (Q-peak) at basal segments of septal, inferior, lateral and anterior walls, as expression of local timing of mechanical activation. Thirty patients (mean age 70.6years; 19 males) were included. Mean left ventricular ejection fraction was 0.28±0.06. Mean QRS duration was 172.5±13.9ms. Fifteen patients showed LBBB with LAD (QRS duration 173±14; EF 0.27±0.06). The other 15 patients had LBBB with a normal QRS axis (QRS duration 172±14; EF 0.29±0.05). Among patients with LAD, Q-peak interval was significantly longer at the anterior wall in comparison to each other walls (septal 201±46ms, inferior 242±58ms, lateral 267±45ms, anterior 302±50ms; p<0.0001). Conversely, in patients without LAD Q-peak interval was longer at lateral wall, when compared to each other (septal 228±65ms, inferior 250±64ms, lateral 328±98ms, anterior 291±86ms; p<0.0001). Patients with heart failure, presenting LBBB and LAD, show a specific pattern of ventricular asynchrony, with latest activation at anterior wall. This finding could affect target vessel selection during CRT procedures in these patients. Copyright © 2017 Elsevier Inc. All rights reserved.

SU-E-J-155: Utilizing Varian TrueBeam Developer Mode for the Quantification of Mechanical Limits and the Simulation of 4D Respiratory Motion

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

Moseley, D; Dave, M

Purpose: Use Varian TrueBeam Developer mode to quantify the mechanical limits of the couch and to simulate 4D respiratory motion. Methods: An in-house MATLAB based GUI was created to make the BEAM XML files. The couch was moved in a triangular wave in the S/I direction with varying amplitudes (1mm, 5mm, 10mm, and 50mm) and periods (3s, 6s, and 9s). The periods were determined by specifying the speed. The theoretical positions were compared to the values recorded by the machine at 50 Hz. HD videos were taken for certain tests as external validation. 4D Respiratory motion was simulated by anmore » A/P MV beam being delivered while the couch moved in an elliptical manner. The ellipse had a major axis of 2 cm (S/I) and a minor axis of 1 cm (A/P). Results: The path planned by the TrueBeam deviated from the theoretical triangular form as the speed increased. Deviations were noticed starting at a speed of 3.33 cm/s (50mm amplitude, 6s period). The greatest deviation occurred in the 50mm- 3s sequence with a correlation value of −0.13 and a 27% time increase; the plan essentially became out of phase. Excluding these two, the plans had correlation values of 0.99. The elliptical sequence effectively simulated a respiratory pattern with a period of 6s. The period could be controlled by changing the speeds or the dose rate. Conclusion: The work first shows the quantification of the mechanical limits of the couch and the speeds at which the proposed plans begin to deviate. These limits must be kept in mind when programming other couch sequences. The methodology can be used to quantify the limits of other axes. Furthermore, the work shows the possibility of creating 4D respiratory simulations without using specialized phantoms or motion-platforms. This can be further developed to program patient-specific breathing patterns.« less

[A new kinematics method of determing elbow rotation axis and evaluation of its feasibility].

PubMed

Han, W; Song, J; Wang, G Z; Ding, H; Li, G S; Gong, M Q; Jiang, X Y; Wang, M Y

2016-04-18

To study a new positioning method of elbow external fixation rotation axis, and to evaluate its feasibility. Four normal adult volunteers and six Sawbone elbow models were brought into this experiment. The kinematic data of five elbow flexion were collected respectively by optical positioning system. The rotation axes of the elbow joints were fitted by the least square method. The kinematic data and fitting results were visually displayed. According to the fitting results, the average moving planes and rotation axes were calculated. Thus, the rotation axes of new kinematic methods were obtained. By using standard clinical methods, the entrance and exit points of rotation axes of six Sawbone elbow models were located under X-ray. And The kirschner wires were placed as the representatives of rotation axes using traditional positioning methods. Then, the entrance point deviation, the exit point deviation and the angle deviation of two kinds of located rotation axes were compared. As to the four volunteers, the indicators represented circular degree and coplanarity of elbow flexion movement trajectory of each volunteer were both about 1 mm. All the distance deviations of the moving axes to the average moving rotation axes of the five volunteers were less than 3 mm. All the angle deviations of the moving axes to the average moving rotation axes of the five volunteers were less than 5°. As to the six Sawbone models, the average entrance point deviations, the average exit point deviations and the average angle deviations of two different rotation axes determined by two kinds of located methods were respectively 1.697 2 mm, 1.838 3 mm and 1.321 7°. All the deviations were very small. They were all in an acceptable range of clinical practice. The values that represent circular degree and coplanarity of volunteer's elbow single curvature movement trajectory are very small. The result shows that the elbow single curvature movement can be regarded as the approximate fixed axis movement. The new method can replace the traditional method in accuracy. It can make up the deficiency of the traditional fixed axis method.

Changing axis deviation and paroxysmal atrial flutter associated with subclinical hyperthyroidism.

PubMed

Patanè, Salvatore; Marte, Filippo

2010-10-08

Subclinical hyperthyroidism is an increasingly recognized entity that is defined as a normal serum free thyroxine and free triiodothyronine levels with a thyroid-stimulating hormone level suppressed below the normal range and usually undetectable. It has been reported that subclinical hyperthyroidism is not associated with coronary heart disease or mortality from cardiovascular causes but it is sufficient to induce arrhythmias including atrial fibrillation and atrial flutter. It has also been reported that increased factor X activity in patients with subclinical hyperthyroidism represents a potential hypercoagulable state. Rarely, it has also been reported intermittent changing axis deviation during atrial fibrillation and during atrial flutter. We present a case of paroxysmal atrial flutter and changing axis deviation associated with subclinical hyperthyroidism, in a 76-year-old Italian man. Also this case focuses attention on the importance of a correct evaluation of subclinical hyperthyroidism. Copyright © 2008 Elsevier Ireland Ltd. All rights reserved.

SU-G-TeP2-04: Comprehensive Machine Isocenter Evaluation with Separation of Gantry, Collimator, and Table Variables

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

Hancock, S; Clements, C; Hyer, D

2016-06-15

Purpose: To develop and demonstrate application of a method that characterizes deviation of linac x-ray beams from the centroid of the volumetric radiation isocenter as a function of gantry, collimator, and table variables. Methods: A set of Winston-Lutz ball-bearing images was used to determine the gantry radiation isocenter as the midrange of deviation values resulting from gantry and collimator rotation. Also determined were displacement of table axis from gantry isocenter and recommended table axis adjustment. The method, previously reported, has been extended to include the effect of collimator walkout by obtaining measurements with 0 and 180 degree collimator rotation formore » each gantry angle. Twelve images were used to characterize the volumetric isocenter for the full range of available gantry, collimator, and table rotations. Results: Three Varian True Beam, two Elekta Infinity and four Versa HD linacs at five institutions were tested using identical methodology. Varian linacs exhibited substantially less deviation due to head sag than Elekta linacs (0.4 mm vs. 1.2 mm on average). One linac from each manufacturer had additional isocenter deviation of 0.3 to 0.4 mm due to jaw instability with gantry and collimator rotation. For all linacs, the achievable isocenter tolerance was dependent on adjustment of collimator position offset, transverse position steering, and alignment of the table axis with gantry isocenter, facilitated by these test results. The pattern and magnitude of table axis wobble vs. table angle was reproducible and unique to each machine. Conclusion: This new method provides a comprehensive set of isocenter deviation values including all variables. It effectively facilitates minimization of deviation between beam center and target (ball-bearing) position. This method was used to quantify the effect of jaw instability on isocenter deviation and to identify the offending jaw. The test is suitable for incorporation into a routine machine QA program. Software development was performed by Radiological Imaging Technology, Inc.« less

Clinical Evaluation of the Root Tear of the Posterior Horn of the Medial Meniscus in Total Knee Arthroplasty for Osteoarthritis

PubMed Central

Park, Sang-Jun

2015-01-01

Purpose To investigate the incidence of root tears of the posterior horn of the medial meniscus in total knee replacement arthroplasty for knee osteoarthritis and retrospectively analyze clinical results and factors associated with root tears. Materials and Methods There were 197 knees of 140 enrolled patients who had undergone total knee replacement arthroplasty between September 2010 and May 2014. The presence of a root tear of the posterior horn of the medial meniscus was confirmed in all patients. Statistical analysis was performed to investigate the correlation between root tears and the possible factors of meniscal tears including gender, age, severity of symptoms (visual analogue scale [VAS] score and medial joint line tenderness), grade of osteoarthritis (Kellgren-Lawrence grading scale), body mass index (BMI), varus deformity, and mechanical axis deviation. Results Meniscal tears were observed in 154 knees (78.17%). The root tear had correlation with the severity of osteoarthritis (p<0.05), varus deformity (p<0.05), mechanical axis deviation (p<0.05), and BMI (p<0.05). Conclusions Factors considered to represent the severity of osteoarthritis were found to be associated with root tears of the medial meniscus posterior horn. Increased BMI seemed to be associated with the increased incidence of root tears of the medial meniscus posterior horn. PMID:26060607

Experimental determination of the navigation error of the 4-D navigation, guidance, and control systems on the NASA B-737 airplane

NASA Technical Reports Server (NTRS)

Knox, C. E.

1978-01-01

Navigation error data from these flights are presented in a format utilizing three independent axes - horizontal, vertical, and time. The navigation position estimate error term and the autopilot flight technical error term are combined to form the total navigation error in each axis. This method of error presentation allows comparisons to be made between other 2-, 3-, or 4-D navigation systems and allows experimental or theoretical determination of the navigation error terms. Position estimate error data are presented with the navigation system position estimate based on dual DME radio updates that are smoothed with inertial velocities, dual DME radio updates that are smoothed with true airspeed and magnetic heading, and inertial velocity updates only. The normal mode of navigation with dual DME updates that are smoothed with inertial velocities resulted in a mean error of 390 m with a standard deviation of 150 m in the horizontal axis; a mean error of 1.5 m low with a standard deviation of less than 11 m in the vertical axis; and a mean error as low as 252 m with a standard deviation of 123 m in the time axis.

Mineral lineation produced by 3-D rotation of rigid inclusions in confined viscous simple shear

NASA Astrophysics Data System (ADS)

Marques, Fernando O.

2016-08-01

The solid-state flow of rocks commonly produces a parallel arrangement of elongate minerals with their longest axes coincident with the direction of flow-a mineral lineation. However, this does not conform to Jeffery's theory of the rotation of rigid ellipsoidal inclusions (REIs) in viscous simple shear, because rigid inclusions rotate continuously with applied shear. In 2-dimensional (2-D) flow, the REI's greatest axis (e1) is already in the shear direction; therefore, the problem is to find mechanisms that can prevent the rotation of the REI about one axis, the vorticity axis. In 3-D flow, the problem is to find a mechanism that can make e1 rotate towards the shear direction, and so generate a mineral lineation by rigid rotation about two axes. 3-D analogue and numerical modelling was used to test the effects of confinement on REI rotation and, for narrow channels (shear zone thickness over inclusion's least axis, Wr < 2), the results show that: (1) the rotational behaviour deviates greatly from Jeffery's model; (2) inclusions with aspect ratio Ar (greatest over least principle axis, e1/e3) > 1 can rotate backwards from an initial orientation w e1 parallel to the shear plane, in great contrast to Jeffery's model; (3) back rotation is limited because inclusions reach a stable equilibrium orientation; (4) most importantly and, in contrast to Jeffery's model and to the 2-D simulations, in 3-D, the confined REI gradually rotated about an axis orthogonal to the shear plane towards an orientation with e1 parallel to the shear direction, thus producing a lineation parallel to the shear direction. The modelling results lead to the conclusion that confined simple shear can be responsible for the mineral alignment (lineation) observed in ductile shear zones.

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

Schiefer, H., E-mail: johann.schiefer@kssg.ch; Peters, S.; Plasswilm, L.

Purpose: For stereotactic radiosurgery, the AAPM Report No. 54 [AAPM Task Group 42 (AAPM, 1995)] requires the overall stability of the isocenter (couch, gantry, and collimator) to be within a 1 mm radius. In reality, a rotating system has no rigid axis and thus no isocenter point which is fixed in space. As a consequence, the isocenter concept is reviewed here. It is the aim to develop a measurement method following the revised definitions. Methods: The mechanical isocenter is defined here by the point which rotates on the shortest path in the room coordinate system. The path is labeled asmore » “isocenter path.” Its center of gravity is assumed to be the mechanical isocenter. Following this definition, an image-based and radiation-free measurement method was developed. Multiple marker pairs in a plane perpendicular to the assumed gantry rotation axis of a linear accelerator are imaged with a smartphone application from several rotation angles. Each marker pair represents an independent measuring system. The room coordinates of the isocenter path and the mechanical isocenter are calculated based on the marker coordinates. The presented measurement method is by this means strictly focused on the mechanical isocenter. Results: The measurement result is available virtually immediately following completion of measurement. When 12 independent measurement systems are evaluated, the standard deviations of the isocenter path points and mechanical isocenter coordinates are 0.02 and 0.002 mm, respectively. Conclusions: The measurement is highly accurate, time efficient, and simple to adapt. It is therefore suitable for regular checks of the mechanical isocenter characteristics of the gantry and collimator rotation axis. When the isocenter path is reproducible and its extent is in the range of the needed geometrical accuracy, it should be taken into account in the planning process. This is especially true for stereotactic treatments and radiosurgery.« less

Accuracy of various impression materials and methods for two implant systems: An effect size study.

PubMed

Schmidt, Alexander; Häussling, Teresa; Rehmann, Peter; Schaaf, Heidrun; Wöstmann, Bernd

2018-04-01

An accurate impression is required for implant treatment. The aim of this in-vitro study was to determine the effect size of the impression material/method, implant system and implant angulation on impression transfer precision. An upper jaw model with three BEGO and three Straumann implants (angulations 0°, 15°, 20°) in the left and right maxilla was used as a reference model. One polyether (Impregum Penta) and two polyvinyl siloxanes (Flexitime Monophase/Aquasil Ultra Monophase) were examined with two impression techniques (open and closed tray). A total of 60 impressions were made. A coordinate measurement machine was used to measure the target variables for 3D-shift, implant axis inclination and implant axis rotation. All the data were subjected to a four-way ANOVA. The effect size (partial eta-squared [η 2 P ]) was reported. The impression material had a significant influence on the 3D shift and the implant axis inclination deviation (p-values=.000), and both factors had very large effect sizes (3D-shift [η 2 P ]=.599; implant axis inclination [η 2 P ]=.298). Impressions made with polyvinyl siloxane exhibited the highest transfer precision. When the angulation of the implants was larger, more deviations occurred for the implant axis rotational deviation. The implant systems and impression methods showed partially significant variations (p-values=.001-.639) but only very small effect sizes (η 2 P =.001-.031). The impression material had the greatest effect size on accuracy in terms of the 3D shift and the implant axis inclination. For multiunit restorations with disparallel implants, polyvinyl siloxane materials should be considered. In addition, the effect size of a multivariate investigation should be reported. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Incidence rates, correlates, and prognosis of electrocardiographic P-wave abnormalities - a nationwide population-based study.

PubMed

Lehtonen, Arttu O; Langén, Ville L; Puukka, Pauli J; Kähönen, Mika; Nieminen, Markku S; Jula, Antti M; Niiranen, Teemu J

Scant data exist on incidence rates, correlates, and prognosis of electrocardiographic P-wave abnormalities in the general population. We recorded ECG and measured conventional cardiovascular risk factors in 5667 Finns who were followed up for incident atrial fibrillation (AF). We obtained repeat ECGs from 3089 individuals 11years later. The incidence rates of prolonged P-wave duration, abnormal P terminal force (PTF), left P-wave axis deviation, and right P-wave axis deviation were 16.0%, 7.4%, 3.4%, and 2.2%, respectively. Older age and higher BMI were associated with incident prolonged P-wave duration and abnormal PTF (P≤0.01). Higher blood pressure was associated with incident prolonged P-wave duration and right P-wave axis deviation (P≤0.01). During follow-up, only prolonged P-wave duration predicted AF (multivariable-adjusted hazard ratio, 1.38; P=0.001). Modifiable risk factors associate with P-wave abnormalities that are common and may represent intermediate steps of atrial cardiomyopathy on a pathway leading to AF. Copyright © 2017 Elsevier Inc. All rights reserved.

Nucleation and growth mechanism of Co-Pt alloy nanowires electrodeposited within alumina template

NASA Astrophysics Data System (ADS)

Srivastav, Ajeet K.; Shekhar, Rajiv

2015-01-01

Co-Pt alloy nanowires were electrodeposited by direct current electrodeposition within nanoporous alumina templates with varying deposition potentials. The effect of deposition potential on nucleation and growth mechanisms during electrodeposition of Co-Pt alloy nanowires was investigated. The less negative deposition potential (-0.9 V) favours the instantaneous nucleation mechanism. The positive deviation from theoretical instantaneous and progressive nucleation mechanisms occurs at higher negative deposition potentials. The hysteresis behaviour and magnetic properties of electrodeposited Co-Pt alloy nanowires altered with varying deposition potential. The easy magnetization direction was in direction perpendicular to the wire axis. The deposition potential dependent change in hysteresis behaviour with increased coercivity and scattered remanence ratio was observed. This is attributed to better crystallinity with reduced defect density and hydrogen evolution causing structural changes at more negative deposition potentials.

High precision dual-axis tracking solar wireless charging system based on the four quadrant photoelectric sensor

NASA Astrophysics Data System (ADS)

Liu, Zhilong; Wang, Biao; Tong, Weichao

2015-08-01

This paper designs a solar automatic tracking wireless charging system based on the four quadrant photoelectric sensor. The system track the sun's rays automatically in real time to received the maximum energy and wireless charging to the load through electromagnetic coupling. Four quadrant photoelectric sensor responsive to the solar spectrum, the system could get the current azimuth and elevation angle of the light by calculating the solar energy incident on the sensor profile. System driver the solar panels by the biaxial movement mechanism to rotate and tilt movement until the battery plate and light perpendicular to each other. Maximize the use of solar energy, and does not require external power supply to achieve energy self-sufficiency. Solar energy can be collected for portable devices and load wireless charging by close electromagnetic field coupling. Experimental data show that: Four quadrant photoelectric sensor more sensitive to light angle measurement. when track positioning solar light, Azimuth deviation is less than 0.8°, Elevation angle deviation is less than 0.6°. Use efficiency of a conventional solar cell is only 10% -20%.The system uses a Four quadrant dual-axis tracking to raise the utilization rate of 25% -35%.Wireless charging electromagnetic coupling efficiency reached 60%.

Investigation of the on-axis atom number density in the supersonic gas jet under high gas backing pressure by simulation

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

Chen, Guanglong; Xu, Yi; Cao, Yunjiu

The supersonic gas jets from conical nozzles are simulated using 2D model. The on-axis atom number density in gas jet is investigated in detail by comparing the simulated densities with the idealized densities of straight streamline model in scaling laws. It is found that the density is generally lower than the idealized one and the deviation between them is mainly dependent on the opening angle of conical nozzle, the nozzle length and the gas backing pressure. The density deviation is then used to discuss the deviation of the equivalent diameter of a conical nozzle from the idealized d{sub eq} inmore » scaling laws. The investigation on the lateral expansion of gas jet indicates the lateral expansion could be responsible for the behavior of the density deviation. These results could be useful for the estimation of cluster size and the understanding of experimental results in laser-cluster interaction experiments.« less

Discrepancy of alignment in different weight bearing conditions before and after high tibial osteotomy.

PubMed

Wang, Joon Ho; Shin, Jung Min; Kim, Hyun Ho; Kang, Seung-Hoon; Lee, Byung Hoon

2017-01-01

To evaluate the differences in the amount of varus malalignment and valgus (over) correction in relation to three different weight bearing conditions from whole leg AP radiographs (single-limb (SL) stance, double-limb (DL) stance, supine position (S)) before and after high tibial osteotomy (HTO), and to evaluate which alignment parameters affect the changes for patients in three different weight bearing conditions. A total of 40 consecutive patients (43 knees) with varus osteoarthritis underwent navigation assisted open wedge HTO. Mechanical axis angle (MA) was measured before and after surgery from hip-to-ankle radiographs taken with patients in three different weight bearing conditions. To find significant factors that affect the alignment differences, several variables including patient demographics, soft tissue laxity, pelvic obliquity, and ground mechanical axis deviation of tibia (calculated by the angle between two lines, tibial anatomical axis and weight-bearing line) were evaluated. Pre-operatively, mean MA measured on SL stance radiographs was significantly more varus than on DL stance (10.1° ± 2.4° and 8.0° ± 2.6°, respectively, p < 0.001), which was significantly more varus than on supine position (6.6° ± 2.6°, p < 0.001). Meanwhile, in patients with post-operatively valgus corrected knee, MA did not show the same pattern of change as with pre-operative varus knee. Mean MA measured on DL stance radiographs was more valgus than in supine position (-3.0 o  ± 2.4 o and -2.6 o  ± 3.1 o , p = 0.455), while mean MA on SL stance radiographs (-2.0 o  ± 2.1 o ) was significantly less valgus than on DL stance (p = 0.002). The ground mechanical axis deviation of tibia showed a significant correlation with MA difference between SL and DL stance radiographs before (β = -0.341, p = 0.045) and after surgery (β = -0.536, p = 0.001). In pre-operative varus knee, the mean MA on SL stance was changed to more varus than on DL stance, which changed to less valgus in post-operative valgus knee. The understanding in discrepancy of alignment in different weight bearing conditions before and after HTO should be considered for the appropriate realignment of the limb. Level II Prospective comparative study.

Regeneration mechanisms in Syllidae (Annelida)

PubMed Central

Ribeiro, Rannyele P.

2018-01-01

Abstract Syllidae is one of the most species‐rich groups within Annelida, with a wide variety of reproductive modes and different regenerative processes. Syllids have striking ability to regenerate their body anteriorly and posteriorly, which in many species is redeployed during sexual (schizogamy) and asexual (fission) reproduction. This review summarizes the available data on regeneration in syllids, covering descriptions of regenerative mechanisms in different species as well as regeneration in relation to reproductive modes. Our survey shows that posterior regeneration is widely distributed in syllids, whereas anterior regeneration is limited in most of the species, excepting those reproducing by fission. The latter reproductive mode is well known for a few species belonging to Autolytinae, Eusyllinae, and Syllinae. Patterns of fission areas have been studied in these animals. Deviations of the regular regeneration pattern or aberrant forms such as bifurcated animals or individuals with multiple heads have been reported for several species. Some of these aberrations show a deviation of the bilateral symmetry and antero‐posterior axis, which, interestingly, can also be observed in the regular branching body pattern of some species of syllids. PMID:29721325

Case report: an electrocardiogram of spontaneous pneumothorax mimicking arm lead reversal.

PubMed

Wieters, J Scott; Carlin, Joseph P; Morris, Andrew

2014-05-01

There are several previously documented findings for electrocardiograms (ECGs) of spontaneous pneumothorax. These findings include axis deviation, T-wave inversion, and right bundle branch block. When an ECG has the arm leads incorrectly placed, the ECG will display right axis deviation and inversion of the P waves in lead I. There have been no previously published ECGs of spontaneous pneumothorax that have shown the same findings as reversal of the limb leads of an ECG. A possible finding of spontaneous pneumothorax is an identical finding to that of an ECG that has been flagged for limb lead reversal. A patient presented in the emergency setting with acute chest pain and shortness of breath caused by a tension pneumothorax. An ECG was administered; findings indicated reversal of the arm leads (right axis deviation and inverted P waves in lead I), but there was no actual limb lead reversal present. ECG findings resolved upon resolution of the pneumothorax. If a patient presents with chest pain and shortness of breath, and the patient's ECG is flagged for limb lead reversal despite being set up correctly, the physician should raise clinical suspicion for a possible spontaneous pneumothorax. Copyright © 2014 Elsevier Inc. All rights reserved.

Upgraded FAA Airfield Capacity Model. Volume 2. Technical Description of Revisions

DTIC Science & Technology

1981-02-01

the threshold t k a the time at which departure k is released FIGURE 3-1 TIME AXIS DIAGRAM OF SINGLE RUNWAY OPERATIONS 3-2 J"- SIGMAR the standard...standard deviation of the interarrival time. SIGMAR - the standard deviation of the arrival runway occupancy time. A-5 SINGLE - program subroutine for

Novel theory for propagation of tilted Gaussian beam through aligned optical system

NASA Astrophysics Data System (ADS)

Xia, Lei; Gao, Yunguo; Han, Xudong

2017-03-01

A novel theory for tilted beam propagation is established in this paper. By setting the propagation direction of the tilted beam as the new optical axis, we establish a virtual optical system that is aligned with the new optical axis. Within the first order approximation of the tilt and off-axis, the propagation of the tilted beam is studied in the virtual system instead of the actual system. To achieve more accurate optical field distributions of tilted Gaussian beams, a complete diffraction integral for a misaligned optical system is derived by using the matrix theory with angular momentums. The theory demonstrates that a tilted TEM00 Gaussian beam passing through an aligned optical element transforms into a decentered Gaussian beam along the propagation direction. The deviations between the peak intensity axis of the decentered Gaussian beam and the new optical axis have linear relationships with the misalignments in the virtual system. ZEMAX simulation of a tilted beam through a thick lens exposed to air shows that the errors between the simulation results and theoretical calculations of the position deviations are less than 2‰ when the misalignments εx, εy, εx', εy' are in the range of [-0.5, 0.5] mm and [-0.5, 0.5]°.

Clinical Results and Complications of Lower Limb Lengthening for Fibular Hemimelia: A Report of Eight Cases.

PubMed

Mishima, Kenichi; Kitoh, Hiroshi; Iwata, Koji; Matsushita, Masaki; Nishida, Yoshihiro; Hattori, Tadashi; Ishiguro, Naoki

2016-05-01

Fibular hemimelia is a rare but the most common congenital long bone deficiency, encompassing a broad range of anomalies from isolated fibular hypoplasia up to substantial femoral and tibial shortening with ankle deformity and foot deficiency. Most cases of fibular hemimelia manifest clinically significant leg length discrepancy (LLD) with time that requires adequate correction by bone lengthening for stable walking. Bone lengthening procedures, especially those for pathological bones, are sometimes associated with severe complications, such as delayed consolidation, fractures, and deformities of the lengthened bones, leading to prolonged healing time and residual LLD at skeletal maturity. The purpose of this study was to review our clinical results of lower limb lengthening for fibular hemimelia.This study included 8 Japanese patients who diagnosed with fibular hemimelia from physical and radiological findings characteristic of fibular hemimelia and underwent single or staged femoral and/or tibial lengthening during growth or after skeletal maturity. LLD, state of the lengthened callus, and bone alignment were evaluated with full-length radiographs of the lower limb. Previous interventions, associated congenital anomalies, regenerate fractures were recorded with reference to medical charts and confirmed on appropriate radiographs. Successful lengthening was defined as the healing index <50 days/cm without regenerate fractures.A significant difference was observed in age at surgery between successful and unsuccessful lengthening. The incidence of regenerate fractures was significantly correlated with callus maturity before frame removal. LLD was corrected within 11 mm, whereas mechanical axis deviated laterally.Particular attention should be paid to the status of callus maturation and the mechanical axis deviation during the treatment period in fibular hemimelia.

Left Axis Deviation in Children Without Previously Known Heart Disease.

PubMed

Schneider, Andrew E; Cannon, Bryan C; Johnson, Jonathan N; Ackerman, Michael J; Wackel, Philip L

2018-02-01

Left axis deviation (LAD) discovered in children via electrocardiogram (ECG) is uncommon but can be associated with heart disease (HD). The optimal diagnostic approach in a seemingly healthy child with LAD is unclear. We sought to better stratify which patients with LAD but without previously known HD may warrant additional workup. A retrospective chart review was performed to identify patients ≥1 to <18 years of age with LAD (QRS frontal plane axis 0 to -90) on an ECG between January 2002 and December 2014. Patients with known HD before their initial ECG were excluded. Overall, 296 patients were identified ( n = 181 [61%] male; mean age: 10.8 ± 4.6 years; mean QRS axis: -24 ± 22°). An echocardiogram was performed in 158 (53%) patients, with 24 (15%) having HD. Compared with those with an echocardiogram but without HD ( n = 134), patients with HD had a more negative mean QRS axis (-42 vs -27°; P = .002) and were more likely to have a QRS axis ≤-42° (58% vs 26%; P = .003), ECG chamber enlargement or hypertrophy (38% vs 5%; P < .0001), and abnormal cardiac physical examination findings (75% vs 8%; P < .0001). LAD discovered in isolation in the asymptomatic pediatric patient may not necessitate further cardiovascular investigation. Clinicians should consider obtaining an echocardiogram in patients with LAD and ECG cardiac chamber enlargement or hypertrophy, a QRS axis ≤-42°, and/or the presence of abnormal cardiac physical examination findings. Copyright © 2018 by the American Academy of Pediatrics.

Variability in alignment of central venous pressure transducer to physiologic reference point in the intensive care unit-A descriptive and correlational study.

PubMed

Sjödin, Carl; Sondergaard, Soren; Johansson, Lotta

2018-06-01

The phlebostatic axis is the most commonly used anatomical external reference point for central venous pressure measurements. Deviation in the central venous pressure transducer alignment from the phlebostatic axis causes inadequate pressure readings, which may affect treatment decisions for critically ill patients in intensive care units. The primary aim of the study was to assess the variability in central venous pressure transducer levelling in the intensive care unit. We also assessed whether patient characteristics impacted on central venous pressure transducer alignment deviation. A sample of 61 critical care nurses was recruited and asked to place a transducer at the appropriate level for central venous pressure measurement. The measurements were performed in the intensive care unit on critically ill patients in supine and Fowler's positions. The variability among the participants using eyeball levelling and a laser levelling device was calculated in both sessions and adjusted for patient characteristics. A significant variation was found among critical care nurses in the horizontal levelling of the pressure transducer placement when measuring central venous pressure in the intensive care unit. Using a laser levelling device did not reduce the deviation from the phlebostatic axis. Patient characteristics had little impact on the deviation in the measurements. The anatomical external landmark for the phlebostatic axis varied between critical care nurses, as the variation in the central venous pressure transducer placement was not reduced with a laser levelling device. Standardisation of a zero-level for vascular pressures should be considered to reduce the variability in vascular pressure readings in the intensive care unit to improve patient treatment decisions. Further studies are needed to evaluate critical care nurses' knowledge and use of central venous pressure monitoring and whether assistive tools and/or routines can improve the accuracy in vascular pressure measurements in intensive care units. Copyright © 2018 Australian College of Critical Care Nurses Ltd. Published by Elsevier Ltd. All rights reserved.

Modeling of roll/pitch determination with horizon sensors - Oblate Earth

NASA Astrophysics Data System (ADS)

Hablani, Hari B.

Model calculations are presented of roll/pitch determinations for oblate Earth, with horizon sensors. Two arrangements of a pair of horizon sensors are considered: left and right of the velocity vactor (i.e., along the pitch axis), and aft and forward (along the roll axis). Two approaches are used to obtain the roll/pitch oblateness corrections: (1) the crossing point approach, where the two crossings of the horizon sensor's scan and the earth's horizon are determined, and (2) by decomposing the angular deviation of the geocentric normal from the geodetic normal into roll and pitch components. It is shown that the two approaches yield essentially the same corrections if two sensors are used simultaneously. However, if the spacecraft is outfitted with only one sensor, the oblateness correction about one axis is far different from that predicted by the geocentric/geodetic angular deviation approach. In this case, the corrections may be calculated on ground for the sensor location under consideration and stored in the flight computer, using the crossing point approach.

Quasi-Sun-Pointing of Spacecraft Using Radiation Pressure

NASA Technical Reports Server (NTRS)

Spilker, Thomas

2003-01-01

A report proposes a method of utilizing solar-radiation pressure to keep the axis of rotation of a small spin-stabilized spacecraft pointed approximately (typically, within an angle of 10 deg to 20 deg) toward the Sun. Axisymmetry is not required. Simple tilted planar vanes would be attached to the outer surface of the body, so that the resulting spacecraft would vaguely resemble a rotary fan, windmill, or propeller. The vanes would be painted black for absorption of Solar radiation. A theoretical analysis based on principles of geometric optics and mechanics has shown that torques produced by Solar-radiation pressure would cause the axis of rotation to precess toward Sun-pointing. The required vane size would be a function of the angular momentum of the spacecraft and the maximum acceptable angular deviation from Sun-pointing. The analysis also shows that the torques produced by the vanes would slowly despin the spacecraft -- an effect that could be counteracted by adding specularly reflecting "spin-up" vanes.

An image registration based ultrasound probe calibration

NASA Astrophysics Data System (ADS)

Li, Xin; Kumar, Dinesh; Sarkar, Saradwata; Narayanan, Ram

2012-02-01

Reconstructed 3D ultrasound of prostate gland finds application in several medical areas such as image guided biopsy, therapy planning and dose delivery. In our application, we use an end-fire probe rotated about its axis to acquire a sequence of rotational slices to reconstruct 3D TRUS (Transrectal Ultrasound) image. The image acquisition system consists of an ultrasound transducer situated on a cradle directly attached to a rotational sensor. However, due to system tolerances, axis of probe does not align exactly with the designed axis of rotation resulting in artifacts in the 3D reconstructed ultrasound volume. We present a rigid registration based automatic probe calibration approach. The method uses a sequence of phantom images, each pair acquired at angular separation of 180 degrees and registers corresponding image pairs to compute the deviation from designed axis. A modified shadow removal algorithm is applied for preprocessing. An attribute vector is constructed from image intensity and a speckle-insensitive information-theoretic feature. We compare registration between the presented method and expert-corrected images in 16 prostate phantom scans. Images were acquired at multiple resolutions, and different misalignment settings from two ultrasound machines. Screenshots from 3D reconstruction are shown before and after misalignment correction. Registration parameters from automatic and manual correction were found to be in good agreement. Average absolute differences of translation and rotation between automatic and manual methods were 0.27 mm and 0.65 degree, respectively. The registration parameters also showed lower variability for automatic registration (pooled standard deviation σtranslation = 0.50 mm, σrotation = 0.52 degree) compared to the manual approach (pooled standard deviation σtranslation = 0.62 mm, σrotation = 0.78 degree).

Grid-Based Projector Augmented Wave (GPAW) Implementation of Quantum Mechanics/Molecular Mechanics (QM/MM) Electrostatic Embedding and Application to a Solvated Diplatinum Complex.

PubMed

Dohn, A O; Jónsson, E Ö; Levi, G; Mortensen, J J; Lopez-Acevedo, O; Thygesen, K S; Jacobsen, K W; Ulstrup, J; Henriksen, N E; Møller, K B; Jónsson, H

2017-12-12

A multiscale density functional theory-quantum mechanics/molecular mechanics (DFT-QM/MM) scheme is presented, based on an efficient electrostatic coupling between the electronic density obtained from a grid-based projector augmented wave (GPAW) implementation of density functional theory and a classical potential energy function. The scheme is implemented in a general fashion and can be used with various choices for the descriptions of the QM or MM regions. Tests on H 2 O clusters, ranging from dimer to decamer show that no systematic energy errors are introduced by the coupling that exceeds the differences in the QM and MM descriptions. Over 1 ns of liquid water, Born-Oppenheimer QM/MM molecular dynamics (MD) are sampled combining 10 parallel simulations, showing consistent liquid water structure over the QM/MM border. The method is applied in extensive parallel MD simulations of an aqueous solution of the diplatinum [Pt 2 (P 2 O 5 H 2 ) 4 ] 4- complex (PtPOP), spanning a total time period of roughly half a nanosecond. An average Pt-Pt distance deviating only 0.01 Å from experimental results, and a ground-state Pt-Pt oscillation frequency deviating by <2% from experimental results were obtained. The simulations highlight a remarkable harmonicity of the Pt-Pt oscillation, while also showing clear signs of Pt-H hydrogen bonding and directional coordination of water molecules along the Pt-Pt axis of the complex.

Comparison Of Methods Used In Cartography For The Skeletonisation Of Areal Objects

NASA Astrophysics Data System (ADS)

Szombara, Stanisław

2015-12-01

The article presents a method that would compare skeletonisation methods for areal objects. The skeleton of an areal object, being its linear representation, is used, among others, in cartographic visualisation. The method allows us to compare between any skeletonisation methods in terms of the deviations of distance differences between the skeleton of the object and its border from one side and the distortions of skeletonisation from another. In the article, 5 methods were compared: Voronoi diagrams, densified Voronoi diagrams, constrained Delaunay triangulation, Straight Skeleton and Medial Axis (Transform). The results of comparison were presented on the example of several areal objects. The comparison of the methods showed that in all the analysed objects the Medial Axis (Transform) gives the smallest distortion and deviation values, which allows us to recommend it.

Nonlinear Elastic Effects on the Energy Flux Deviation of Ultrasonic Waves in GR/EP Composites

NASA Technical Reports Server (NTRS)

Prosser, William H.; Kriz, R. D.; Fitting, Dale W.

1992-01-01

In isotropic materials, the direction of the energy flux (energy per unit time per unit area) of an ultrasonic plane wave is always along the same direction as the normal to the wave front. In anisotropic materials, however, this is true only along symmetry directions. Along other directions, the energy flux of the wave deviates from the intended direction of propagation. This phenomenon is known as energy flux deviation and is illustrated. The direction of the energy flux is dependent on the elastic coefficients of the material. This effect has been demonstrated in many anisotropic crystalline materials. In transparent quartz crystals, Schlieren photographs have been obtained which allow visualization of the ultrasonic waves and the energy flux deviation. The energy flux deviation in graphite/epoxy (gr/ep) composite materials can be quite large because of their high anisotropy. The flux deviation angle has been calculated for unidirectional gr/ep composites as a function of both fiber orientation and fiber volume content. Experimental measurements have also been made in unidirectional composites. It has been further demonstrated that changes in composite materials which alter the elastic properties such as moisture absorption by the matrix or fiber degradation, can be detected nondestructively by measurements of the energy flux shift. In this research, the effects of nonlinear elasticity on energy flux deviation in unidirectional gr/ep composites were studied. Because of elastic nonlinearity, the angle of the energy flux deviation was shown to be a function of applied stress. This shift in flux deviation was modeled using acoustoelastic theory and the previously measured second and third order elastic stiffness coefficients for T300/5208 gr/ep. Two conditions of applied uniaxial stress were considered. In the first case, the direction of applied uniaxial stress was along the fiber axis (x3) while in the second case it was perpendicular to the fiber axis along the laminate stacking direction (x1).

Postimplant left ventricular assist device fit analysis using three-dimensional reconstruction.

PubMed

Truong, Thang V; Stanfield, J Ryan; Chaffin, John S; Elkins, C Craig; Kanaly, Paul J; Horstmanshof, Douglas A; Long, James W; Snyder, Trevor A

2013-01-01

Left ventricular assist devices (LVADs) are blood pumps that augment the function of the failing heart to improve perfusion, resulting in improved survival. For LVADs to effectively unload the left ventricle, the inflow cannula (IC) should be unobstructed and ideally aligned with the heart's mitral valve (MV). We examined IC orientation deviation from a hypothesized conventional angle (45° right-posterior) and the approximate angle for direct IC-MV alignment in many patients. Three-dimensional anatomic models were created from computed tomography scans for 24 LVAD-implanted patients, and angles were measured between the IC and the apical z-axis in both the coronal and the sagittal planes. Common surgical IC angulation was found to be 22 ± 15° rightward and 21 ± 12° posterior from the apical z-axis; 38% (n = 9) of patients fell in this range. Direct IC-MV angulation was found to be 34 ± 8° rightward and 15 ± 7° posterior; only 8% (n = 2) of patients fell in this range. Rightward deviation toward ventricular septal wall and anterior deviation toward LV anterior freewall are associated with mortalities more so than leftward and posterior deviation. In conclusion, anatomic reconstruction may be a useful preoperative tool to obtain general population and patient-specific alignment for optimal LVAD implantation.

The Mid-Ocean Ridge.

ERIC Educational Resources Information Center

Macdonald, Kenneth C.; Fox, Paul J.

1990-01-01

Described are concepts involved with the formation and actions of the Mid-Ocean Ridge. Sea-floor spreading, the magma supply model, discontinuities, off-axis structures, overlaps and deviation, and aquatic life are discussed. (CW)

A novel verification method using a plastic scintillator imagining system for assessment of gantry sag in radiotherapy.

PubMed

Tsuneda, Masato; Nishio, Teiji; Saito, Akito; Tanaka, Sodai; Suzuki, Tatsuhiko; Kawahara, Daisuke; Matsushita, Keiichiro; Nishio, Aya; Ozawa, Shuichi; Karasawa, Kumiko; Nagata, Yasushi

2018-06-01

High accuracy of the beam-irradiated position is required for high-precision radiation therapy such as stereotactic body radiation therapy (SBRT), volumetric modulated arc therapy (VMAT), and intensity modulated radiation therapy (IMRT). Users generally perform the verification of the mechanical and radiation isocenters using the star shot test and the Winston Lutz test that allow evaluation of the displacement at the isocenter. However, these methods are unable to evaluate directly and quantitatively the sagging angle that is caused by the weight of the gantry itself along the gantry rotation axis. In addition, the verification of the central axis of the irradiated beam that is not dependent at the isocenter is needed for the mechanical quality assurance of a nonisocentric irradiation technique. In this study, we have developed a prototype system for the verification of three-dimensional (3D) beam alignment and we have verified the system concept for 3D isocentricity. Our system allows detection of the central axis in 3D coordinates and evaluation of the irradiated oblique angle to the gantry rotation axis, i.e., the sagging angle. In order to measure the central axis of the irradiated beam in 3D coordinates, we constructed the prototype verification system consisting of a column-shaped plastic scintillator (CoPS), a truncated cone-shaped mirror (TCsM), and a cooled charged-coupled device (CCD) camera. This verification system was irradiated with 6-MV photon beams and the scintillation light was measured using the CCD camera. The central axis on the axial plane (two-dimensional (2D) central axis) was acquired from the integration of the scintillation light along the major axis of the CoPS, and the central axis in 3D coordinates (3D central axis) was acquired from two curve-shaped profiles which were reflected by the TCsM. We verified the calculation accuracy of the gantry rotation axis, θ z . Additionally, we calculated the 3D central axis and the sagging angle at each gantry angle. We acquired the measurement images composed of the 2D central axis and the two curve-shaped profiles. The relationship between the irradiated and measured angles with respect to the gantry rotation axis had good linearity. The mean and standard deviation of the difference between the irradiated and measured angles were 0.012 and 0.078 degrees, respectively. The size of the 2D and 3D radiation isocenters were 0.470 and 0.652 mm on the axial plane and in 3D coordinates, respectively. The sagging angles were -0.31, 0.39, and 0.38 degrees at the gantry angles of 0, 180, and 180E degrees, respectively. We developed a novel verification system, designated as the "kompeito shot test system," to verify the 3D beam alignment. This system concept works for both verification of the 3D isocentricity and the direct evaluation of the sagging angle. Next, we want to improve the aspects of this system, such as the shape and the type of scintillator, to increase the system accuracy and nonisocentric beam alignment performance. © 2018 American Association of Physicists in Medicine.

Finite difference modelling of dipole acoustic logs in a poroelastic formation with anisotropic permeability

NASA Astrophysics Data System (ADS)

He, Xiao; Hu, Hengshan; Wang, Xiuming

2013-01-01

Sedimentary rocks can exhibit strong permeability anisotropy due to layering, pre-stresses and the presence of aligned microcracks or fractures. In this paper, we develop a modified cylindrical finite-difference algorithm to simulate the borehole acoustic wavefield in a saturated poroelastic medium with transverse isotropy of permeability and tortuosity. A linear interpolation process is proposed to guarantee the leapfrog finite difference scheme for the generalized dynamic equations and Darcy's law for anisotropic porous media. First, the modified algorithm is validated by comparison against the analytical solution when the borehole axis is parallel to the symmetry axis of the formation. The same algorithm is then used to numerically model the dipole acoustic log in a borehole with its axis being arbitrarily deviated from the symmetry axis of transverse isotropy. The simulation results show that the amplitudes of flexural modes vary with the dipole orientation because the permeability tensor of the formation is dependent on the wellbore azimuth. It is revealed that the attenuation of the flexural wave increases approximately linearly with the radial permeability component in the direction of the transmitting dipole. Particularly, when the borehole axis is perpendicular to the symmetry axis of the formation, it is possible to estimate the anisotropy of permeability by evaluating attenuation of the flexural wave using a cross-dipole sonic logging tool according to the results of sensitivity analyses. Finally, the dipole sonic logs in a deviated borehole surrounded by a stratified porous formation are modelled using the proposed finite difference code. Numerical results show that the arrivals and amplitudes of transmitted flexural modes near the layer interface are sensitive to the wellbore inclination.

Microstructures and superconducting properties of high performance MgB2 thin films deposited from a high-purity, dense Mg-B target.

PubMed

Li, G Z; Susner, M A; Bohnenstiehl, S D; Sumption, M D; Collings, E W

2015-12-01

High quality, c -axis oriented, MgB 2 thin films were successfully grown on 6H-SiC substrates using pulsed laser deposition (PLD) with subsequent in situ annealing. To obtain high purity films free from oxygen contamination, a dense Mg-B target was specially made from a high temperature, high pressure reaction of Mg and B to form large-grained (10~50 µm) MgB 2 . Microstructural analysis via electron microscopy found that the resulting grains of the film were composed of ultrafine columnar grains of 19-30 nm. XRD analysis showed the MgB 2 films to be c -axis oriented; the a -axis and c -axis lattice parameters were determined to be 3.073 ± 0.005 Å and 3.528 ± 0.010 Å, respectively. The superconducting critical temperature, T c,onset , increased monotonically as the annealing temperature was increased, varying from 25.2 K to 33.7 K. The superconducting critical current density as determined from magnetic measurements, J cm , at 5 K, was 10 5 A/cm 2 at 7.8 T; at 20 K, 10 5 A/cm 2 was reached at 3.1 T. The transport and pinning properties of these films were compared to "powder-in-tube" (PIT) and "internal-infiltration" (AIMI) processed wires. Additionally, examination of the pinning mechanism showed that when scaled to the peak in the pinning curve, the films follow the grain boundary, or surface, pinning mechanism quite well, and are similar to the response seen for C doped PIT and AIMI strands, in contrast to the behavior seen in undoped PIT wires, in which deviations are seen at high b ( b = B/B c2 ). On the other hand, the magnitude of the pinning force was similar for the thin films and AIMI conductors, unlike the values from connectivity-suppressed PIT strands.

The relation of motion sickness to the spatial-temporal properties of velocity storage

NASA Technical Reports Server (NTRS)

Dai, Mingjia; Kunin, Mikhail; Raphan, Theodore; Cohen, Bernard; Young, L. R. (Principal Investigator)

2003-01-01

Tilting the head in roll to or from the upright while rotating at a constant velocity (roll while rotating, RWR) alters the position of the semicircular canals relative to the axis of rotation. This produces vertical and horizontal nystagmus, disorientation, vertigo, and nausea. With recurrent exposure, subjects habituate and can make more head movements before experiencing overpowering motion sickness. We questioned whether promethazine lessened the vertigo or delayed the habituation, whether habituation of the vertigo was related to the central vestibular time constant, i.e., to the time constant of velocity storage, and whether the severity of the motion sickness was related to deviation of the axis of eye velocity from gravity. Sixteen subjects received promethazine and placebo in a double-blind, crossover study in two consecutive 4-day test series 1 month apart, termed series I and II. Horizontal and vertical eye movements were recorded with video-oculography while subjects performed roll head movements of approx. 45 degrees over 2 s to and from the upright position while being rotated at 138 degrees /s around a vertical axis. Motion sickness was scaled from 1 (no sickness) to an endpoint of 20, at which time the subject was too sick to continue or was about to vomit. Habituation was determined by the number of head movements that subjects made before reaching the maximum motion sickness score of 20. Head movements increased steadily in each session with repeated testing, and there was no difference between the number of head movements made by the promethazine and placebo groups. Horizontal and vertical angular vestibulo-ocular reflex (aVOR) time constants declined in each test, with the declines being closely correlated to the increase in the number of head movements. The strength of vertiginous sensation was associated with the amount of deviation of the axis of eye velocity from gravity; the larger the deviation of the eye velocity axis from gravity, the more severe the motion sickness. Thus, promethazine neither reduced the nausea associated with RWR, nor retarded or hastened habituation. The inverse relationship between the aVOR time constants and number of head movements to motion sickness, and the association of the severity of motion sickness with the extent, strength, and time of deviation of eye velocity from gravity supports the postulate that the spatiotemporal properties of velocity storage, which are processed between the nodulus and uvula of the vestibulocerebellum and the vestibular nuclei, are likely to represent the source of the conflict responsible for producing motion sickness.

Interferometric rotation sensor

NASA Technical Reports Server (NTRS)

Walsh, T. M.

1972-01-01

Sensor generates interference fringes varying in number (horizontally and vertically) as a function of the total angular deviation relative to the line-of-sight axis. Device eliminates errors from zero or null shift due to lack of electrical circuitry stability.

Longitudinal, lateral and transverse axes of forearm muscles influence the crosstalk in the mechanomyographic signals during isometric wrist postures.

PubMed

Islam, Md Anamul; Sundaraj, Kenneth; Ahmad, R Badlishah; Sundaraj, Sebastian; Ahamed, Nizam Uddin; Ali, Md Asraf

2014-01-01

In mechanomyography (MMG), crosstalk refers to the contamination of the signal from the muscle of interest by the signal from another muscle or muscle group that is in close proximity. The aim of the present study was two-fold: i) to quantify the level of crosstalk in the mechanomyographic (MMG) signals from the longitudinal (Lo), lateral (La) and transverse (Tr) axes of the extensor digitorum (ED), extensor carpi ulnaris (ECU) and flexor carpi ulnaris (FCU) muscles during isometric wrist flexion (WF) and extension (WE), radial (RD) and ulnar (UD) deviations; and ii) to analyze whether the three-directional MMG signals influence the level of crosstalk between the muscle groups during these wrist postures. Twenty, healthy right-handed men (mean ± SD: age = 26.7±3.83 y; height = 174.47±6.3 cm; mass = 72.79±14.36 kg) participated in this study. During each wrist posture, the MMG signals propagated through the axes of the muscles were detected using three separate tri-axial accelerometers. The x-axis, y-axis, and z-axis of the sensor were placed in the Lo, La, and Tr directions with respect to muscle fibers. The peak cross-correlations were used to quantify the proportion of crosstalk between the different muscle groups. The average level of crosstalk in the MMG signals generated by the muscle groups ranged from: 34.28-69.69% for the Lo axis, 27.32-52.55% for the La axis and 11.38-25.55% for the Tr axis for all participants and their wrist postures. The Tr axes between the muscle groups showed significantly smaller crosstalk values for all wrist postures [F (2, 38) = 14-63, p<0.05, η2 = 0.416-0.769]. The results may be applied in the field of human movement research, especially for the examination of muscle mechanics during various types of the wrist postures.

A Measuring System for Well Logging Attitude and a Method of Sensor Calibration

PubMed Central

Ren, Yong; Wang, Yangdong; Wang, Mijian; Wu, Sheng; Wei, Biao

2014-01-01

This paper proposes an approach for measuring the azimuth angle and tilt angle of underground drilling tools with a MEMS three-axis accelerometer and a three-axis fluxgate sensor. A mathematical model of well logging attitude angle is deduced based on combining space coordinate transformations and algebraic equations. In addition, a system implementation plan of the inclinometer is given in this paper, which features low cost, small volume and integration. Aiming at the sensor and assembly errors, this paper analyses the sources of errors, and establishes two mathematical models of errors and calculates related parameters to achieve sensor calibration. The results show that this scheme can obtain a stable and high precision azimuth angle and tilt angle of drilling tools, with the deviation of the former less than ±1.4° and the deviation of the latter less than ±0.1°. PMID:24859028

A measuring system for well logging attitude and a method of sensor calibration.

PubMed

Ren, Yong; Wang, Yangdong; Wang, Mijian; Wu, Sheng; Wei, Biao

2014-05-23

This paper proposes an approach for measuring the azimuth angle and tilt angle of underground drilling tools with a MEMS three-axis accelerometer and a three-axis fluxgate sensor. A mathematical model of well logging attitude angle is deduced based on combining space coordinate transformations and algebraic equations. In addition, a system implementation plan of the inclinometer is given in this paper, which features low cost, small volume and integration. Aiming at the sensor and assembly errors, this paper analyses the sources of errors, and establishes two mathematical models of errors and calculates related parameters to achieve sensor calibration. The results show that this scheme can obtain a stable and high precision azimuth angle and tilt angle of drilling tools, with the deviation of the former less than ±1.4° and the deviation of the latter less than ±0.1°.

Reliability of frames of reference used for tibial component rotation in total knee arthroplasty.

PubMed

Page, Stephen R; Deakin, Angela H; Payne, Anthony P; Picard, Frederic

2011-01-01

This study evaluated seven different frames of reference used for tibial component rotation in total knee arthroplasty (TKA) to determine which ones showed good reliability between bone specimens. An optoelectronic system based around a computer-assisted surgical navigation system was used to measure and locate 34 individual anatomical landmarks on 40 tibias. Each particular frame of reference was reconstructed from a group of data points taken from the surface of each bone. The transverse axis was used as the baseline to which the other axes were compared, and the differences in angular rotation between the other six reference frames and the transverse axis were calculated. There was high variability in the tibial rotational alignment associated with all frames of reference. Of the references widely used in current TKA procedures, the tibial tuberosity axis and the anterior condylar axis had lower standard deviations (6.1° and 7.3°, respectively) than the transmalleolar axis and the posterior condylar axis (9.3° for both). In conclusion, we found high variability in the frames of reference used for tibial rotation alignment. However, the anterior condylar axis and transverse axis may warrant further tests with the use of navigation. Combining different frames of reference such as the tibial tuberosity axis, anterior condylar axis and transverse axis may reduce the range of errors found in all of these measurements.

Portal imaging based definition of the planning target volume during pelvic irradiation for gynecological malignancies.

PubMed

Mock, U; Dieckmann, K; Wolff, U; Knocke, T H; Pötter, R

1999-08-01

Geometrical accuracy in patient positioning can vary substantially during external radiotherapy. This study estimated the set-up accuracy during pelvic irradiation for gynecological malignancies for determination of safety margins (planning target volume, PTV). Based on electronic portal imaging devices (EPID), 25 patients undergoing 4-field pelvic irradiation for gynecological malignancies were analyzed with regard to set-up accuracy during the treatment course. Regularly performed EPID images were used in order to systematically assess the systematic and random component of set-up displacements. Anatomical matching of verification and simulation images was followed by measuring corresponding distances between the central axis and anatomical features. Data analysis of set-up errors referred to the x-, y-,and z-axes. Additionally, cumulative frequencies were evaluated. A total of 50 simulation films and 313 verification images were analyzed. For the anterior-posterior (AP) beam direction mean deviations along the x- and z-axes were 1.5 mm and -1.9 mm, respectively. Moreover, random errors of 4.8 mm (x-axis) and 3.0 mm (z-axis) were determined. Concerning the latero-lateral treatment fields, the systematic errors along the two axes were calculated to 2.9 mm (y-axis) and -2.0 mm (z-axis) and random errors of 3.8 mm and 3.5 mm were found, respectively. The cumulative frequency of misalignments < or =5 mm showed values of 75% (AP fields) and 72% (latero-lateral fields). With regard to cumulative frequencies < or =10 mm quantification revealed values of 97% for both beam directions. During external pelvic irradiation therapy for gynecological malignancies, EPID images on a regular basis revealed acceptable set-up inaccuracies. Safety margins (PTV) of 1 cm appear to be sufficient, accounting for more than 95% of all deviations.

Can the recovery of lower limb fractures be achieved by use of 3D printing mirror model?

PubMed

Zhang, Wenxi; Ji, Yueping; Wang, Xinming; Liu, Jie; Li, Dong

2017-11-01

The mirror imaging 3D printing model can be used a as a reference for anatomical reduction in unilateral lower limb fractures. However, the premise of using mirror technology is that the bilateral lower limb bones are similar enough. Because one side had a fracture, it was impossible to compare this directly to the other side. Usually, surgeons think that the bilateral bones are symmetrical and use mirror technology without judging their symmetry. In patients with a unilateral lower limb bone fracture, we measured the long axis and short axis of the three selected transverse sections of the bilateral long bone for comparison to judge the symmetry of the bilateral long bones on CT images. Then, we printed a life-size normal mirror image of the long bone that is similar to the affected side. The model was used as a reference for the anatomical reduction of fractures and preoperative practice. Seventy-eight patients with lower limb bone fracture were included in this study. 24 groups of data were generated according to the same level and same axis. There were significant differences between the short axis of the left and right femoral condyle 5cm from the intercondylar keel (p=0.011), and the short axis of the distal tibia 15cm from the ankle dome (p=0.026). There was no significant difference between the left and right sides in the other 22 groups. Of all of the patients in our research, 3 patients decided to forego the surgical treatment and the operation was performed on the model instead, and the lengths of 2 patients showed deviation in actual operations, preventing anatomical reduction. The remaining 73 patients used the pre-bended plates and screws from preoperative practice in the actual operations, and postoperative X-ray examinations showed that the length of the deviation was within the permissible range. The "Comparison of long axis and short axis of three equidistant transverse sections" method makes it easy to judge the symmetry of the bilateral long bones, and prevents the blindness of preoperative planning using the contralateral mirror model directly. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparative evaluation of toric intraocular lens alignment and visual quality with image-guided surgery and conventional three-step manual marking.

PubMed

Titiyal, Jeewan S; Kaur, Manpreet; Jose, Cijin P; Falera, Ruchita; Kinkar, Ashutosh; Bageshwar, Lalit Ms

2018-01-01

To compare toric intraocular lens (IOL) alignment assisted by image-guided surgery or manual marking methods and its impact on visual quality. This prospective comparative study enrolled 80 eyes with cataract and astigmatism ≥1.5 D to undergo phacoemulsification with toric IOL alignment by manual marking method using bubble marker (group I, n=40) or Callisto eye and Z align (group II, n=40). Postoperatively, accuracy of alignment and visual quality was assessed with a ray tracing aberrometer. Primary outcome measure was deviation from the target axis of implantation. Secondary outcome measures were visual quality and acuity. Follow-up was performed on postoperative days (PODs) 1 and 30. Deviation from the target axis of implantation was significantly less in group II on PODs 1 and 30 (group I: 5.5°±3.3°, group II: 3.6°±2.6°; p =0.005). Postoperative refractive cylinder was -0.89±0.35 D in group I and -0.64±0.36 D in group II ( p =0.003). Visual acuity was comparable between both the groups. Visual quality measured in terms of Strehl ratio ( p <0.05) and modulation transfer function (MTF) ( p <0.05) was significantly better in the image-guided surgery group. Significant negative correlation was observed between deviation from target axis and visual quality parameters (Strehl ratio and MTF) ( p <0.05). Image-guided surgery allows precise alignment of toric IOL without need for reference marking. It is associated with superior visual quality which correlates with the precision of IOL alignment.

Wellens' syndrome and other electrocardiographic changes in a patient with a left anterior descending artery subocclusion associated with a left main coronary artery subocclusion.

PubMed

Patanè, Salvatore; Marte, Filippo

2011-09-01

Changing axis deviation has been reported also during atrial fibrillation or atrial flutter. Changing axis deviation has been also reported during acute myocardial infarction associated with atrial fibrillation too or at the end of atrial fibrillation during acute myocardial infarction. Patients with unstable angina have a higher incidence of left main coronary artery (LMCA) and proximal left anterior descending (LAD) coronary artery disease compared to patients with stable angina pectoris. In 1982, Wellens and colleagues described two electrocardiographic patterns that were predictive of critical narrowing of the proximal LAD artery, and were subsequently termed Wellens' syndrome. The criteria were: a) prior history of chest pain, b) little or no cardiac enzyme elevation, c) no pathologic precordial ST segment elevation, d) no loss of precordial R waves, and e) biphasic T waves in leads V2 and V3, or asymmetric, often deeply inverted T waves in leads V2 and V3. The ECG changes are best recognized outside the episode of anginal pain. Lead aVR and lead v1 ST segment elevation, during chest pain, has been reported in patients with LMCA disease with ST segment depression in leads V3, V4 and V5 (with maximal depression in V4).We present a case of changing axis deviation in a 37-year-old Italian man with a LAD coronary artery subocclusion associated with a LMCA subocclusion. This case focuses attention on the importance of the recognition of the patterns suspected for LAD coronary artery disease or for LMCA disease. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

Comparative evaluation of toric intraocular lens alignment and visual quality with image-guided surgery and conventional three-step manual marking

PubMed Central

Titiyal, Jeewan S; Kaur, Manpreet; Jose, Cijin P; Falera, Ruchita; Kinkar, Ashutosh; Bageshwar, Lalit MS

2018-01-01

Purpose To compare toric intraocular lens (IOL) alignment assisted by image-guided surgery or manual marking methods and its impact on visual quality. Patients and methods This prospective comparative study enrolled 80 eyes with cataract and astigmatism ≥1.5 D to undergo phacoemulsification with toric IOL alignment by manual marking method using bubble marker (group I, n=40) or Callisto eye and Z align (group II, n=40). Postoperatively, accuracy of alignment and visual quality was assessed with a ray tracing aberrometer. Primary outcome measure was deviation from the target axis of implantation. Secondary outcome measures were visual quality and acuity. Follow-up was performed on postoperative days (PODs) 1 and 30. Results Deviation from the target axis of implantation was significantly less in group II on PODs 1 and 30 (group I: 5.5°±3.3°, group II: 3.6°±2.6°; p=0.005). Postoperative refractive cylinder was −0.89±0.35 D in group I and −0.64±0.36 D in group II (p=0.003). Visual acuity was comparable between both the groups. Visual quality measured in terms of Strehl ratio (p<0.05) and modulation transfer function (MTF) (p<0.05) was significantly better in the image-guided surgery group. Significant negative correlation was observed between deviation from target axis and visual quality parameters (Strehl ratio and MTF) (p<0.05). Conclusion Image-guided surgery allows precise alignment of toric IOL without need for reference marking. It is associated with superior visual quality which correlates with the precision of IOL alignment. PMID:29731603

The gap technique does not rotate the femur parallel to the epicondylar axis.

PubMed

Matziolis, Georg; Boenicke, Hinrich; Pfiel, Sascha; Wassilew, Georgi; Perka, Carsten

2011-02-01

In the analysis of painful total knee replacements, the surgical epicondylar axis (SEA) has become established as a standard in the diagnosis of femoral component rotation. It remains unclear whether the gap technique widely used to determine femoral rotation, when applied correctly, results in a rotation parallel to the SEA. In this prospective study, 69 patients (69 joints) were included who received a navigated bicondylar surface replacement due to primary arthritis of the knee joint. In 67 cases in which a perfect soft-tissue balancing of the extension gap (<1° asymmetry) was achieved, the flexion gap and the rotation of the femoral component necessary for its symmetry was determined and documented. The femoral component was implanted additionally taking into account the posterior condylar axis and the Whiteside's line. Postoperatively, the rotation of the femoral component to the SEA was determined and this was used to calculate the angle between a femur implanted according to the gap technique and the SEA. If the gap technique had been used consistently, it would have resulted in a deviation of the femoral components by -0.6° ± 2.9° (-7.4°-5.9°) from the SEA. The absolute deviation would have been 2.4° ± 1.8°, with a range between 0.2° and 7.4°. Even if the extension gap is perfectly balanced, the gap technique does not lead to a parallel alignment of the femoral component to the SEA. Since the clinical results of this technique are equivalent to those of the femur first technique in the literature, an evaluation of this deviation as a malalignment must be considered critically.

T-wave axis deviation is associated with biomarkers of low-grade inflammation. Findings from the MOLI-SANI study.

PubMed

Bonaccio, Marialaura; Di Castelnuovo, Augusto; Rago, Livia; de Curtis, Amalia; Assanelli, Deodato; Badilini, Fabio; Vaglio, Martino; Costanzo, Simona; Persichillo, Mariarosaria; Cerletti, Chiara; Donati, Maria Benedetta; de Gaetano, Giovanni; Iacoviello, Licia

2015-11-25

T-wave axis deviation (TDev) may help identifying subjects at risk for major cardiac events and mortality, but the pathogenesis of TDev is not well established; in particular, the possible association between TDev and inflammation is unexplored and unknown. We aimed at investigating the association between low-grade inflammation and TDev abnormalities by conducting a cross-sectional analysis on 17,507 subjects apparently free from coronary heart and haematological diseases enrolled in the MOLI-SANI study. TDev was measured from a standard 12-lead resting electrocardiogram. High sensitivity (Hs) C-reactive protein (CRP), leukocyte (WBC) and platelet counts, neutrophil or granulocyte to lymphocyte ratios were used as markers of inflammation. In multivariable model subjects reporting high CRP levels had higher odds of having borderline and abnormal TDev (OR=1.70; 95 %CI: 1.53-1.90 and OR=1.72; 95 %CI: 1.23-2.41, respectively); the association was still significant, although reduced, after controlling for body mass index (OR=1.17; 95 %CI: 1.05-1.32, for borderline and OR=1.46; 95 %CI: 1.03-2.08, for abnormal). Similarly, higher neutrophil or granulocyte to lymphocyte ratios were associated with increased odds of having abnormal TDev. Neither platelet nor leukocyte counts were associated with abnormal TDev. The relationship between CRP with TDev abnormalities was significantly stronger in men, in non- obese or normotensive individuals, and in those without metabolic syndrome. In conclusion, C-reactive protein and some cellular biomarkers of inflammation such as granulocyte or neutrophil to lymphocyte ratios were independently associated with abnormal TDev, especially in subjects at low CVD risk. These results suggest that a low-grade inflammation likely contributes to the pathogenesis of T- wave axis deviation.

Method and apparatus for providing high bandwidth, low noise mechanical I/O for computer systems

DOEpatents

Rosenberg, Louis B.

1998-01-01

A method and apparatus for providing high bandwidth and low noise mechanical input and output for computer systems. A gimbal mechanism provides two revolute degrees of freedom to an object about two axes of rotation. A linear axis member is coupled to the gimbal mechanism at the intersection of the two axes of rotation. The linear axis member is capable of being translated along a third axis to provide a third degree of freedom. The user object is coupled to the linear axis member and is thus translatable along the third axis so that the object can be moved along all three degrees of freedom. Transducers associated with the provided degrees of freedom include sensors and actuators and provide an electromechanical interface between the object and a digital processing system. Capstan drive mechanisms transmit forces between the transducers and the object. The linear axis member can also be rotated about its lengthwise axis to provide a fourth degree of freedom, and, optionally, a floating gimbal mechanism is coupled to the linear axis member to provide fifth and sixth degrees of freedom to an object. Transducer sensors are associated with the fourth, fifth, and sixth degrees of freedom. The interface is well suited for simulations of medical procedures and simulations in which an object such as a stylus or a joystick is moved and manipulated by the user.

Multiple degree-of-freedom mechanical interface to a computer system

DOEpatents

Rosenberg, Louis B.

2001-01-01

A method and apparatus for providing high bandwidth and low noise mechanical input and output for computer systems. A gimbal mechanism provides two revolute degrees of freedom to an object about two axes of rotation. A linear axis member is coupled to the gimbal mechanism at the intersection of the two axes of rotation. The linear axis member is capable of being translated along a third axis to provide a third degree of freedom. The user object is coupled to the linear axis member and is thus translatable along the third axis so that the object can be moved along all three degrees of freedom. Transducers associated with the provided degrees of freedom include sensors and actuators and provide an electromechanical interface between the object and a digital processing system. Capstan drive mechanisms transmit forces between the transducers and the object. The linear axis member can also be rotated about its lengthwise axis to provide a fourth degree of freedom, and, optionally, a floating gimbal mechanism is coupled to the linear axis member to provide fifth and sixth degrees of freedom to an object. Transducer sensors are associated with the fourth, fifth, and sixth degrees of freedom. The interface is well suited for simulations of medical procedures and simulations in which an object such as a stylus or a joystick is moved and manipulated by the user.

Outcome reporting following navigated high tibial osteotomy of the knee: a systematic review.

PubMed

Yan, James; Musahl, Volker; Kay, Jeffrey; Khan, Moin; Simunovic, Nicole; Ayeni, Olufemi R

2016-11-01

This systematic review evaluates radiographic and clinical outcome reporting following navigated high tibial osteotomy (HTO). Conventional HTO was used as a control to compare outcomes and furthermore investigate the quality of evidence in studies reporting outcomes for navigated HTO. It was hypothesized that navigated HTO will show superior clinical and radiographic outcomes compared to conventional HTO. Two independent reviewers searched PubMed, Ovid (MEDLINE), EMBASE, and Cochrane databases for studies reporting outcomes following navigated HTO. Titles, abstracts, and full-text were screened in duplicate using an a priori inclusion and exclusion criteria. Descriptive statistics were calculated using Minitab ® statistical software. Methodological Index for Nonrandomized Studies (MINORS) and Cochrane Risk of Bias Scores were used to evaluate methodological quality. Thirty-four studies which involved 2216 HTOs were analysed in this review, 1608 (72.6 %) navigated HTOs and 608 (27.4 %) conventional HTOs. The majority of studies were of level IV evidence (16). Clinical outcomes were reported in knee and function scores or range of motion comparisons. Postoperative clinical and functional scores were improved by navigated HTO although it is not demonstrated if there is significant improvement compared to conventional HTO. Most common clinical outcome score reported was Lysholm scores (6) which report postoperative scores of 87.8 (standard deviation 5.9) and 88.8 (standard deviation 5.9) for conventional and navigation-assisted HTO, respectively. Radiographic outcomes reported commonly were weight-bearing mechanical axis, coronal plane angle, and posterior tibial slope angle in the sagittal plane. Studies have shown HTO gives significant correction of mechanical alignment and navigated HTO produces significantly less change in posterior tibial slope postoperatively compared to conventional. The mean MINORS for the 17 non-comparative studies was 9/16, and 15/24 for the 14 non-randomized comparative studies. Navigation HTO results in improved mechanical axis alignment and demonstrates significantly better control over the tibial slope angle change postoperatively compared to conventional methods; however, these improvements have not yet been reflected in clinical outcome scores. Overall the studies report HTO does create significantly improved knee scores and functions compared to patients' preoperative ratings regardless of technique. Future studies on HTO outcomes need to focus on consistency of outcome reporting. IV.

Relationship between the tibial mechanical axis and bony anatomical landmarks of the calf and foot as measured on radiographs obtained with a new laser-calibrated position.

PubMed

He, Peiheng; Zhu, Qi; Zhang, Zhaohui; Zou, Xuenong; Xu, Dongliang

2013-01-01

To investigate relationship between the tibial mechanical axis and bony landmarks of the calf and foot by developing a new laser-calibrated position for radiography of the lower limb. A total of 120 volunteers were randomly divided into two groups. All subjects were marked with skin projection of the hypothetical axis of the calf on the frontal and sagittal planes. Radiographs of weight-bearing full-length lower-limb were obtained by the laser-calibrated positioning in the experimental group, and by the use of conventional technique in the control group. To consider the rotation of the calf, radiological features of the knee and ankle were investigated. The relationship between the tibial mechanical axis and the bony landmarks of the calf and foot were also measured. Anteroposterior view depicted a tangential projection on the superior/inferior tibiofibular syndesmosis and between lateral malleolus and talus in ankle mortise in the experimental group. Bony overlap on the superior/inferior tibiofibular syndesmosis and between lateral malleolus and talus was seen in control group. On the tangential projection, it also presented a clear wheel-like contour of the medial femoral condyle, but a partial overlap between medial femoral condyle and tibial plateau. The femoral joint angle between the connecting line at the lowest point of the medial and lateral femoral condyles and the tibial mechanical axis was 83.6° ± 2.49° in the experimental group and 85.3° ± 2.18° in the control group (P < 0.001). The tibial tubercle-axis distance from the center of the medial and middle one-third of the tibial tubercle to the tibial mechanical axis was 1.5 mm in the experimental group and 3.7 mm in the control group (P < 0.05). The malleoli-axis distance from the midpoint of the bimalleolar line joining the tips of the medial and lateral malleoli to the tibial mechanical axis was 1.9 mm in the experimental group and 6.9 mm in the control group (P < 0.001). Lateral view showed no difference between the tibial mechanical axis and the fibular reference line within two groups. In the new radiographic position, our data indicate that the hypothetical tibial mechanical axis and fibular reference line, obtained by marking the specified anatomic landmarks of the calf and foot, are located more closely to the tibial mechanical axis by correcting the rotation of the calf and foot during the radiography. On anteroposterior view, the tibial mechanical axis was approximately 2 mm medial to the center of the ankle. This indicates that the hypothetical tibial mechanical axis marked on the skin could be referred to guide the tibial osteotomy in total knee arthroplasty.

Laparoscopic simulation interface

DOEpatents

Rosenberg, Louis B.

2006-04-04

A method and apparatus for providing high bandwidth and low noise mechanical input and output for computer systems. A gimbal mechanism provides two revolute degrees of freedom to an object about two axes of rotation. A linear axis member is coupled to the gimbal mechanism at the intersection of the two axes of rotation. The linear axis member is capable of being translated along a third axis to provide a third degree of freedom. The user object is coupled to the linear axis member and is thus translatable along the third axis so that the object can be moved along all three degrees of freedom. Transducers associated with the provided degrees of freedom include sensors and actuators and provide an electromechanical interface between the object and a digital processing system. Capstan drive mechanisms transmit forces between the transducers and the object. The linear axis member can also be rotated about its lengthwise axis to provide a fourth degree of freedom, and, optionally, a floating gimbal mechanism is coupled to the linear axis member to provide fifth and sixth degrees of freedom to an object. Transducer sensors are associated with the fourth, fifth, and sixth degrees of freedom. The interface is well suited for simulations of medical procedures and simulations in which an object such as a stylus or a joystick is moved and manipulated by the user.

Vertical force and wrist deviation angle in a sample of elderly people using walkers.

PubMed

Leung, Cherng-Yee; Yeh, Po-Chan

2013-02-01

Walkers are frequently used by elderly people with weak lower limbs and limited balance, but the ergonomic relationship between the use of a walker and stress on the upper limbs is relatively unstudied. The current study assessed wrist deviation and vertical force among elderly individuals using a walker for assistance in walking. 60 elderly volunteers (M age = 81.0 yr., SD = 8.8) participated, 30 of whom frequently used a walker, and 30 who had no such prior experience. Data were obtained from four load cells and a twin-axis wrist goniometer during assisted ambulation using the walker. No significant group difference was found in gait cycle. Significant wrist deviation occurred, with ulnar deviation/dorsiflexion of the right hand, which was greater than that of the left. Non-experienced participants had larger dorsiflexion than experienced participants. Experienced participants produced larger vertical force than non-experienced participants. The greaterthe wrist deviation, the greater was the vertical force. The horizontal handles of most marketed walkers cause wrist deviations. This is a concern for users, clinicians, and related industries. Improvements in walker design should be considered.

Patient-specific positioning guides for total knee arthroplasty: no significant difference between final component alignment and pre-operative digital plan except for tibial rotation.

PubMed

Boonen, Bert; Schotanus, Martijn G M; Kerens, Bart; Hulsmans, Frans-Jan; Tuinebreijer, Wim E; Kort, Nanne P

2017-09-01

To assess whether there is a significant difference between the alignment of the individual femoral and tibial components (in the frontal, sagittal and horizontal planes) as calculated pre-operatively (digital plan) and the actually achieved alignment in vivo obtained with the use of patient-specific positioning guides (PSPGs) for TKA. It was hypothesised that there would be no difference between post-op implant position and pre-op digital plan. Twenty-six patients were included in this non-inferiority trial. Software permitted matching of the pre-operative MRI scan (and therefore calculated prosthesis position) to a pre-operative CT scan and then to a post-operative full-leg CT scan to determine deviations from pre-op planning in all three anatomical planes. For the femoral component, mean absolute deviations from planning were 1.8° (SD 1.3), 2.5° (SD 1.6) and 1.6° (SD 1.4) in the frontal, sagittal and transverse planes, respectively. For the tibial component, mean absolute deviations from planning were 1.7° (SD 1.2), 1.7° (SD 1.5) and 3.2° (SD 3.6) in the frontal, sagittal and transverse planes, respectively. Absolute mean deviation from planned mechanical axis was 1.9°. The a priori specified null hypothesis for equivalence testing: the difference from planning is >3 or <-3 was rejected for all comparisons except for the tibial transverse plane. PSPG was able to adequately reproduce the pre-op plan in all planes, except for the tibial rotation in the transverse plane. Possible explanations for outliers are discussed and highlight the importance for adequate training surgeons before they start using PSPG in their day-by-day practise. Prospective cohort study, Level II.

Electronic Absolute Cartesian Autocollimator

NASA Technical Reports Server (NTRS)

Leviton, Douglas B.

2006-01-01

An electronic absolute Cartesian autocollimator performs the same basic optical function as does a conventional all-optical or a conventional electronic autocollimator but differs in the nature of its optical target and the manner in which the position of the image of the target is measured. The term absolute in the name of this apparatus reflects the nature of the position measurement, which, unlike in a conventional electronic autocollimator, is based absolutely on the position of the image rather than on an assumed proportionality between the position and the levels of processed analog electronic signals. The term Cartesian in the name of this apparatus reflects the nature of its optical target. Figure 1 depicts the electronic functional blocks of an electronic absolute Cartesian autocollimator along with its basic optical layout, which is the same as that of a conventional autocollimator. Referring first to the optical layout and functions only, this or any autocollimator is used to measure the compound angular deviation of a flat datum mirror with respect to the optical axis of the autocollimator itself. The optical components include an illuminated target, a beam splitter, an objective or collimating lens, and a viewer or detector (described in more detail below) at a viewing plane. The target and the viewing planes are focal planes of the lens. Target light reflected by the datum mirror is imaged on the viewing plane at unit magnification by the collimating lens. If the normal to the datum mirror is parallel to the optical axis of the autocollimator, then the target image is centered on the viewing plane. Any angular deviation of the normal from the optical axis manifests itself as a lateral displacement of the target image from the center. The magnitude of the displacement is proportional to the focal length and to the magnitude (assumed to be small) of the angular deviation. The direction of the displacement is perpendicular to the axis about which the mirror is slightly tilted. Hence, one can determine the amount and direction of tilt from the coordinates of the target image on the viewing plane.

Measuring (subglacial) bedform orientation, length, and longitudinal asymmetry - Method assessment.

PubMed

Jorge, Marco G; Brennand, Tracy A

2017-01-01

Geospatial analysis software provides a range of tools that can be used to measure landform morphometry. Often, a metric can be computed with different techniques that may give different results. This study is an assessment of 5 different methods for measuring longitudinal, or streamlined, subglacial bedform morphometry: orientation, length and longitudinal asymmetry, all of which require defining a longitudinal axis. The methods use the standard deviational ellipse (not previously applied in this context), the longest straight line fitting inside the bedform footprint (2 approaches), the minimum-size footprint-bounding rectangle, and Euler's approximation. We assess how well these methods replicate morphometric data derived from a manually mapped (visually interpreted) longitudinal axis, which, though subjective, is the most typically used reference. A dataset of 100 subglacial bedforms covering the size and shape range of those in the Puget Lowland, Washington, USA is used. For bedforms with elongation > 5, deviations from the reference values are negligible for all methods but Euler's approximation (length). For bedforms with elongation < 5, most methods had small mean absolute error (MAE) and median absolute deviation (MAD) for all morphometrics and thus can be confidently used to characterize the central tendencies of their distributions. However, some methods are better than others. The least precise methods are the ones based on the longest straight line and Euler's approximation; using these for statistical dispersion analysis is discouraged. Because the standard deviational ellipse method is relatively shape invariant and closely replicates the reference values, it is the recommended method. Speculatively, this study may also apply to negative-relief, and fluvial and aeolian bedforms.

77 FR 58971 - Airworthiness Directives; Eurocopter France (Eurocopter) Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-25

... prompted by flight crew reports of deviations between the displayed attitude on the attitude display screen and the independent electromechanical standby attitude indicator. The proposed actions [[Page 58972... helicopters. EASA advises that a slow drift in the roll axis on the pilot's and co-pilot's attitude display...

78 FR 20234 - Airworthiness Directives; Eurocopter France Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-04

... prompted by flight crew reports of deviations between the displayed attitude on the attitude display screen and the independent electromechanical standby attitude indicator. The actions of this AD are intended... helicopters. EASA advises that a slow drift in the roll axis on the pilot's and co-pilot's attitude display...

Relative Contributions of the Midcarpal and Radiocarpal Joints to Dart-Thrower's Motion at the Wrist.

PubMed

Kane, Patrick M; Vopat, Bryan G; Mansuripur, P Kaveh; Gaspar, Michael P; Wolfe, Scott W; Crisco, Joseph J; Got, Christopher

2018-03-01

To identify the relative contributions of the radiocarpal (RC) and midcarpal (MC) joints to dart-thrower's motion (DTM) of the wrist. Six cadaveric upper extremities were fixed to a custom-designed loading jig allowing for pure moment-rotation analysis in 24 different directions of wrist motion. Each specimen was tested in 3 states: intact, simulated radiocarpal fusion (sRCF) and simulated pancarpal fusion (sPCF). Moments of ± 1.5 Nm were applied at each of 24 directions for each state and the resulting wrist rotation recorded. Data from each specimen were reduced to compute the range of motion (ROM) envelopes and the orientation of the ROM for the 3 different states. The ROM was significantly decreased in the sRCF and sPCF groups compared with the intact group in the directions of the pure extension, radial extension, ulnar flexion, and ulnar deviation. No significant difference in ROM was detected between the sRCF and sPCF groups in any direction. The ROM envelopes for the intact, sRCF, and sPCF groups were all oriented obliquely to the axis of pure wrist flexion-extension near a path of ulnar flexion-radial extension, consistent with prior reports on DTM. Although both simulated fusion types decreased ROM compared with the intact wrist, the principal direction of wrist motion along the path of DTM was not significantly altered by simulated RCF or PCF. These findings suggest that the RC and MC joints can each contribute to a similar mechanical axis of motion located along the path of DTM when the other joint has been eliminated via fusion. Surgical options such as partial wrist fusions may maintain the native wrist's mechanical axis if either the RC or the MC joint is preserved, despite significant reduction in overall ROM. Copyright © 2018 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Role of gravity-based information on the orientation and localization of the perceived body midline.

PubMed

Ceyte, Hadrien; Cian, Corinne; Nougier, Vincent; Olivier, Isabelle; Trousselard, Marion

2007-01-01

The present study focused on the influence of gravity-based information on the orientation and localization of the perceived body midline. The orientation was investigated by the rolling adjustment of a rod on the subjects' Z-axis and the localization by the horizontal adjustment of a visual dot as being straight ahead. Experiment 1 investigated the effect of the dissociation between the Z-axis and the direction of gravity by placing subjects in roll tilt and supine postures. In roll tilt, the perception of the body midline orientation was deviated in the direction of body tilt and the perception of its localization was deviated in the opposite direction. In the supine body orientation, estimates of the Z-axis and straight-ahead remained veridical as when the body was upright. Experiment 2 highlighted the relative importance of the otolithic and tactile information using diffuse pressure stimulation. The estimation of body midline orientation was modified contrarily to the estimation of its localization. Thus, subjects had no absolute representation of their egocentric space. The main hypothesis regarding the dissociation between the orientation and localization of the body midline may be related to a difference in the integration of sensory information. It can be suggested that the horizontal component of the vestibulo-ocular reflex (VOR) contributed to the perceived localization of the body midline, whereas its orientation was mainly influenced by tactile information.

The effect of migration of instantaneous centre of knee orthosis rotation during gait - in vivo displacement measurements in two experimental variants.

PubMed

Bogucki, Artur J

2014-01-01

The knee joint is a bicondylar hinge two-level joint with six degrees of freedom. The location of the functional axis of flexion-extension motion is still a subject of research and discussions. During the swing phase, the femoral condyles do not have direct contact with the tibial articular surfaces and the intra-articular space narrows with increasing weight bearing. The geometry of knee movements is determined by the shape of articular surfaces. A digital recording of the gait of a healthy volunteer was analysed. In the first experimental variant, the subject was wearing a knee orthosis controlling flexion and extension with a hinge-type single-axis joint. In the second variant, the examination involved a hinge-type double-axis orthosis. Statistical analysis involved mathematically calculated values of displacement P. Scatter graphs with a fourth-order polynomial trend line with a confidence interval of 0.95 due to noise were prepared for each experimental variant. In Variant 1, the average displacement was 15.1 mm, the number of tests was 43, standard deviation was 8.761, and the confidence interval was 2.2. The maximum value of displacement was 30.9 mm and the minimum value was 0.7 mm. In Variant 2, the average displacement was 13.4 mm, the number of tests was 44, standard deviation was 7.275, and the confidence interval was 1.8. The maximum value of displacement was 30.2 mm and the minimum value was 3.4 mm. An analysis of moving averages for both experimental variants revealed that displacement trends for both types of orthosis were compatible from the mid-stance to the mid-swing phase. 1. The method employed in the experiment allows for determining the alignment between the axis of the knee joint and that of shin and thigh orthoses. 2. Migration of the single and double-axis orthoses during the gait cycle exceeded 3 cm. 3. During weight bearing, the double-axis orthosis was positioned more correctly. 4. The study results may be helpful in designing new hinge-type knee joints.

Two-screen single-shot electron spectrometer for laser wakefield accelerated electron beams.

PubMed

Soloviev, A A; Starodubtsev, M V; Burdonov, K F; Kostyukov, I Yu; Nerush, E N; Shaykin, A A; Khazanov, E A

2011-04-01

The laser wakefield acceleration electron beams can essentially deviate from the axis of the system, which distinguishes them greatly from beams of conventional accelerators. In case of energy measurements by means of a permanent-magnet electron spectrometer, the deviation angle can affect accuracy, especially for high energies. A two-screen single-shot electron spectrometer that correctly allows for variations of the angle of entry is considered. The spectrometer design enables enhancing accuracy of measuring narrow electron beams significantly as compared to a one-screen spectrometer with analogous magnetic field, size, and angular acceptance. © 2011 American Institute of Physics

Fracture modes in off-axis fiber composites

NASA Technical Reports Server (NTRS)

Sinclair, J. H.; Chamis, C. C.

1978-01-01

Criteria were developed for identifying, characterizing, and quantifying fracture modes in high-modulus graphite-fiber/resin unidirectional composites subjected to off-axis tensile loading. Procedures are described which use sensitivity analyses and off-axis data to determine the uniaxial strength of fiber composites. It was found that off-axis composites fail by three fracture modes which produce unique fracture surface characteristics. The stress that dominates each fracture mode and the load angle range of its dominance can be identified. Linear composite mechanics is adequate to describe quantitatively the mechanical behavior of off-axis composites. The uniaxial strengths predicted from off-axis data are comparable to these measured in uniaxial tests.

Cerebellar cathodal tDCS interferes with recalibration and spatial realignment during prism adaptation procedure in healthy subjects.

PubMed

Panico, Francesco; Sagliano, Laura; Grossi, Dario; Trojano, Luigi

2016-06-01

The aim of this study is to clarify the specific role of the cerebellum during prism adaptation procedure (PAP), considering its involvement in early prism exposure (i.e., in the recalibration process) and in post-exposure phase (i.e., in the after-effect, related to spatial realignment). For this purpose we interfered with cerebellar activity by means of cathodal transcranial direct current stimulation (tDCS), while young healthy individuals were asked to perform a pointing task on a touch screen before, during and after wearing base-left prism glasses. The distance from the target dot in each trial (in terms of pixels) on horizontal and vertical axes was recorded and served as an index of accuracy. Results on horizontal axis, that was shifted by prism glasses, revealed that participants who received cathodal stimulation showed increased rightward deviation from the actual position of the target while wearing prisms and a larger leftward deviation from the target after prisms removal. Results on vertical axis, in which no shift was induced, revealed a general trend in the two groups to improve accuracy through the different phases of the task, and a trend, more visible in cathodal stimulated participants, to worsen accuracy from the first to the last movements in each phase. Data on horizontal axis allow to confirm that the cerebellum is involved in all stages of PAP, contributing to early strategic recalibration process, as well as to spatial realignment. On vertical axis, the improving performance across the different stages of the task and the worsening accuracy within each task phase can be ascribed, respectively, to a learning process and to the task-related fatigue. Copyright © 2016 Elsevier Inc. All rights reserved.

Vertical force and wrist deviation angle when using a walker to stand up and sit down.

PubMed

Leung, Cherng-Yee; Yeh, Po-Chan

2011-08-01

Research investigating walkers suggests that safety and assistance for the elderly with weak lower limbs were important. However, the relationship between the use of a walker and the upper limbs has received little investigation. Standing up and sitting down are important daily activities. Therefore, the aim of this study was to explore wrist deviation and vertical force among elderly individuals using a walker for assistance to stand up and sit down. In total, 64 elderly volunteers (M age = 80.22, SD = 9.36) were enrolled. Data were obtained from four load cells and a twin-axis wrist goniometer. Wrist deviation and vertical force were examined when participants used a walker with horizontal handles to assist in standing up and sitting down. Significant wrist angle deviation occurred with the use of a walker, with dorsiflexion of the right hand greater than that of the left. Males exerted significantly greater vertical force. In the sitting position, greater ulnar deviation was seen among experienced walker users, whereas during standing, experienced users exhibited greater dorsiflexion. The horizontal handles of most marketed walkers may cause user wrist deviations, suggesting researchers should pursue improvements in walker design.

Child mortality, hypothalamic-pituitary-adrenal axis activity and cellular aging in mothers.

PubMed

Barha, Cindy K; Salvante, Katrina G; Hanna, Courtney W; Wilson, Samantha L; Robinson, Wendy P; Altman, Rachel M; Nepomnaschy, Pablo A

2017-01-01

Psychological challenges, including traumatic events, have been hypothesized to increase the age-related pace of biological aging. Here we test the hypothesis that psychological challenges can affect the pace of telomere attrition, a marker of cellular aging, using data from an ongoing longitudinal-cohort study of Kaqchikel Mayan women living in a population with a high frequency of child mortality, a traumatic life event. Specifically, we evaluate the associations between child mortality, maternal telomere length and the mothers' hypothalamic-pituitary-adrenal axis (HPAA), or stress axis, activity. Child mortality data were collected in 2000 and 2013. HPAA activity was assessed by quantifying cortisol levels in first morning urinary specimens collected every other day for seven weeks in 2013. Telomere length (TL) was quantified using qPCR in 55 women from buccal specimens collected in 2013. Shorter TL with increasing age was only observed in women who experienced child mortality (p = 0.015). Women with higher average basal cortisol (p = 0.007) and greater within-individual variation (standard deviation) in basal cortisol (p = 0.053) presented shorter TL. Non-parametric bootstrapping to estimate mediation effects suggests that HPAA activity mediates the effect of child mortality on TL. Our results are, thus, consistent with the hypothesis that traumatic events can influence cellular aging and that HPAA activity may play a mediatory role. Future large-scale longitudinal studies are necessary to confirm our results and further explore the role of the HPAA in cellular aging, as well as to advance our understanding of the underlying mechanisms involved.

Child mortality, hypothalamic-pituitary-adrenal axis activity and cellular aging in mothers

PubMed Central

Barha, Cindy K.; Salvante, Katrina G.; Hanna, Courtney W.; Wilson, Samantha L.; Robinson, Wendy P.; Altman, Rachel M.

2017-01-01

Psychological challenges, including traumatic events, have been hypothesized to increase the age-related pace of biological aging. Here we test the hypothesis that psychological challenges can affect the pace of telomere attrition, a marker of cellular aging, using data from an ongoing longitudinal-cohort study of Kaqchikel Mayan women living in a population with a high frequency of child mortality, a traumatic life event. Specifically, we evaluate the associations between child mortality, maternal telomere length and the mothers’ hypothalamic-pituitary-adrenal axis (HPAA), or stress axis, activity. Child mortality data were collected in 2000 and 2013. HPAA activity was assessed by quantifying cortisol levels in first morning urinary specimens collected every other day for seven weeks in 2013. Telomere length (TL) was quantified using qPCR in 55 women from buccal specimens collected in 2013. Results: Shorter TL with increasing age was only observed in women who experienced child mortality (p = 0.015). Women with higher average basal cortisol (p = 0.007) and greater within-individual variation (standard deviation) in basal cortisol (p = 0.053) presented shorter TL. Non-parametric bootstrapping to estimate mediation effects suggests that HPAA activity mediates the effect of child mortality on TL. Our results are, thus, consistent with the hypothesis that traumatic events can influence cellular aging and that HPAA activity may play a mediatory role. Future large-scale longitudinal studies are necessary to confirm our results and further explore the role of the HPAA in cellular aging, as well as to advance our understanding of the underlying mechanisms involved. PMID:28542264

Deployment and evaluation of a dual-sensor autofocusing method for on-machine measurement of patterns of small holes on freeform surfaces.

PubMed

Chen, Xiaomei; Longstaff, Andrew; Fletcher, Simon; Myers, Alan

2014-04-01

This paper presents and evaluates an active dual-sensor autofocusing system that combines an optical vision sensor and a tactile probe for autofocusing on arrays of small holes on freeform surfaces. The system has been tested on a two-axis test rig and then integrated onto a three-axis computer numerical control (CNC) milling machine, where the aim is to rapidly and controllably measure the hole position errors while the part is still on the machine. The principle of operation is for the tactile probe to locate the nominal positions of holes, and the optical vision sensor follows to focus and capture the images of the holes. The images are then processed to provide hole position measurement. In this paper, the autofocusing deviations are analyzed. First, the deviations caused by the geometric errors of the axes on which the dual-sensor unit is deployed are estimated to be 11 μm when deployed on a test rig and 7 μm on the CNC machine tool. Subsequently, the autofocusing deviations caused by the interaction of the tactile probe, surface, and small hole are mathematically analyzed and evaluated. The deviations are a result of the tactile probe radius, the curvatures at the positions where small holes are drilled on the freeform surface, and the effect of the position error of the hole on focusing. An example case study is provided for the measurement of a pattern of small holes on an elliptical cylinder on the two machines. The absolute sum of the autofocusing deviations is 118 μm on the test rig and 144 μm on the machine tool. This is much less than the 500 μm depth of field of the optical microscope. Therefore, the method is capable of capturing a group of clear images of the small holes on this workpiece for either implementation.

Effect of Random Circuit Fabrication Errors on Small Signal Gain and Phase in Helix Traveling Wave Tubes

NASA Astrophysics Data System (ADS)

Pengvanich, P.; Chernin, D. P.; Lau, Y. Y.; Luginsland, J. W.; Gilgenbach, R. M.

2007-11-01

Motivated by the current interest in mm-wave and THz sources, which use miniature, difficult-to-fabricate circuit components, we evaluate the statistical effects of random fabrication errors on a helix traveling wave tube amplifier's small signal characteristics. The small signal theory is treated in a continuum model in which the electron beam is assumed to be monoenergetic, and axially symmetric about the helix axis. Perturbations that vary randomly along the beam axis are introduced in the dimensionless Pierce parameters b, the beam-wave velocity mismatch, C, the gain parameter, and d, the cold tube circuit loss. Our study shows, as expected, that perturbation in b dominates the other two. The extensive numerical data have been confirmed by our analytic theory. They show in particular that the standard deviation of the output phase is linearly proportional to standard deviation of the individual perturbations in b, C, and d. Simple formulas have been derived which yield the output phase variations in terms of the statistical random manufacturing errors. This work was supported by AFOSR and by ONR.

Fabrication and correction of freeform surface based on Zernike polynomials by slow tool servo

NASA Astrophysics Data System (ADS)

Cheng, Yuan-Chieh; Hsu, Ming-Ying; Peng, Wei-Jei; Hsu, Wei-Yao

2017-10-01

Recently, freeform surface widely using to the optical system; because it is have advance of optical image and freedom available to improve the optical performance. For freeform optical fabrication by integrating freeform optical design, precision freeform manufacture, metrology freeform optics and freeform compensate method, to modify the form deviation of surface, due to production process of freeform lens ,compared and provides more flexibilities and better performance. This paper focuses on the fabrication and correction of the free-form surface. In this study, optical freeform surface using multi-axis ultra-precision manufacturing could be upgrading the quality of freeform. It is a machine equipped with a positioning C-axis and has the CXZ machining function which is also called slow tool servo (STS) function. The freeform compensate method of Zernike polynomials results successfully verified; it is correction the form deviation of freeform surface. Finally, the freeform surface are measured experimentally by Ultrahigh Accurate 3D Profilometer (UA3P), compensate the freeform form error with Zernike polynomial fitting to improve the form accuracy of freeform.

Quality control methods for linear accelerator radiation and mechanical axes alignment.

PubMed

Létourneau, Daniel; Keller, Harald; Becker, Nathan; Amin, Md Nurul; Norrlinger, Bernhard; Jaffray, David A

2018-06-01

The delivery accuracy of highly conformal dose distributions generated using intensity modulation and collimator, gantry, and couch degrees of freedom is directly affected by the quality of the alignment between the radiation beam and the mechanical axes of a linear accelerator. For this purpose, quality control (QC) guidelines recommend a tolerance of ±1 mm for the coincidence of the radiation and mechanical isocenters. Traditional QC methods for assessment of radiation and mechanical axes alignment (based on pointer alignment) are time consuming and complex tasks that provide limited accuracy. In this work, an automated test suite based on an analytical model of the linear accelerator motions was developed to streamline the QC of radiation and mechanical axes alignment. The proposed method used the automated analysis of megavoltage images of two simple task-specific phantoms acquired at different linear accelerator settings to determine the coincidence of the radiation and mechanical isocenters. The sensitivity and accuracy of the test suite were validated by introducing actual misalignments on a linear accelerator between the radiation axis and the mechanical axes using both beam steering and mechanical adjustments of the gantry and couch. The validation demonstrated that the new QC method can detect sub-millimeter misalignment between the radiation axis and the three mechanical axes of rotation. A displacement of the radiation source of 0.2 mm using beam steering parameters was easily detectable with the proposed collimator rotation axis test. Mechanical misalignments of the gantry and couch rotation axes of the same magnitude (0.2 mm) were also detectable using the new gantry and couch rotation axis tests. For the couch rotation axis, the phantom and test design allow detection of both translational and tilt misalignments with the radiation beam axis. For the collimator rotation axis, the test can isolate the misalignment between the beam radiation axis and the mechanical collimator rotation axis from the impact of field size asymmetry. The test suite can be performed in a reasonable time (30-35 min) due to simple phantom setup, prescription-based beam delivery, and automated image analysis. As well, it provides a clear description of the relationship between axes. After testing the sensitivity of the test suite to beam steering and mechanical errors, the results of the test suite were used to reduce the misalignment errors of the linac to less than 0.7-mm radius for all axes. The proposed test suite offers sub-millimeter assessment of the coincidence of the radiation and mechanical isocenters and the test automation reduces complexity with improved efficiency. The test suite results can be used to optimize the linear accelerator's radiation to mechanical isocenter alignment by beam steering and mechanical adjustment of gantry and couch. © 2018 American Association of Physicists in Medicine.

Toggle mechanism for pinching metal tubes

NASA Technical Reports Server (NTRS)

Stengard, E. O. (Inventor)

1979-01-01

A toggle mechanism pinches a metal tube and maintains the tube in a pinched condition, without fracturing. The toggle mechanism includes a plunger translatable along a longitudinal axis, as well as a pair of links pivoted about a common axis extending through an end of the plunger. One of the links also pivots about a fixed axis. A free end of the other link carries a push link which the other link translates at right angles to the plunger longitudinal axis. First and second sides of the tube bear against a first stop block and are engaged by the push link when a compression spring, attached to the plunger, is suddenly released to irreversibly drive the plunger along its longitudinal axis so the pivot point of the two links is driven to an over travel position.

Comparison of five-axis milling and rapid prototyping for implant surgical templates.

PubMed

Park, Ji-Man; Yi, Tae-Kyoung; Koak, Jai-Young; Kim, Seong-Kyoon; Park, Eun-Jin; Heo, Seong-Joo

2014-01-01

This study aims to compare and evaluate the accuracy of surgical templates fabricated using coordinate synchronization processing with five-axis milling and design-related processing with rapid prototyping (RP). Master phantoms with 10 embedded gutta-percha cylinders hidden under artificial gingiva were fabricated and imaged using cone beam computed tomography. Vectors of the hidden cylinders were extracted and transferred to those of the planned implants through reverse engineering using virtual planning software. An RP-produced template was fabricated by stereolithography in photopolymer at the RP center according to planned data. Metal sleeves were bonded after holes were bored (group RP). For the milled template, milling coordinates were synchronized using the conversion process for the coordinate synchronization platform located on the model's bottom. Metal bushings were set on holes milled on the five-axis milling machine, on which the model was fixed through the coordinate synchronization plate, and the framework was constructed on the model using orthodontic resin (group CS). A computed tomography image was taken with templates firmly fixed on models using anchor pins (RP) or anchor screws (CS). The accuracy was analyzed via reverse engineering. Differences between the two groups were compared by repeated measures two-factor analysis. From the reverse-engineered image of the template on the experimental model, RP-produced templates showed significantly larger deviations than did milled surgical guides. Maximum deviations of the group RP were 1.58 mm (horizontal), 1.68 mm (vertical), and 8.51 degrees (angular); those of the group CS were 0.68 mm (horizontal), 0.41 mm (vertical), and 3.23 degrees (angular). A comparison of milling and RP template production methods showed that a vector-milled surgical guide had significantly smaller deviations than did an RP-produced template. The accuracy of computer-guided milled surgical templates was within the safety margin of previous studies.

A Comparison of Coarse-Grained and Continuum Models for Membrane Bending in Lipid Bilayer Fusion Pores

PubMed Central

Yoo, Jejoong; Jackson, Meyer B.; Cui, Qiang

2013-01-01

To establish the validity of continuum mechanics models quantitatively for the analysis of membrane remodeling processes, we compare the shape and energies of the membrane fusion pore predicted by coarse-grained (MARTINI) and continuum mechanics models. The results at these distinct levels of resolution give surprisingly consistent descriptions for the shape of the fusion pore, and the deviation between the continuum and coarse-grained models becomes notable only when the radius of curvature approaches the thickness of a monolayer. Although slow relaxation beyond microseconds is observed in different perturbative simulations, the key structural features (e.g., dimension and shape of the fusion pore near the pore center) are consistent among independent simulations. These observations provide solid support for the use of coarse-grained and continuum models in the analysis of membrane remodeling. The combined coarse-grained and continuum analysis confirms the recent prediction of continuum models that the fusion pore is a metastable structure and that its optimal shape is neither toroidal nor catenoidal. Moreover, our results help reveal a new, to our knowledge, bowing feature in which the bilayers close to the pore axis separate more from one another than those at greater distances from the pore axis; bowing helps reduce the curvature and therefore stabilizes the fusion pore structure. The spread of the bilayer deformations over distances of hundreds of nanometers and the substantial reduction in energy of fusion pore formation provided by this spread indicate that membrane fusion can be enhanced by allowing a larger area of membrane to participate and be deformed. PMID:23442963

[Activity of the hypothalamo-pituitary-adrenals axis in the Siberian tiger (Panthera tigris altaica) in captivity and in the wild, and their dynamics throughout the year].

PubMed

Naidenko, S V; Ivanov, E A; Lukarevskiĭ, V S; Hernandez-Blanko, J A; Sorokin, P A; Litvinov, M N; Kotliar, A K; Rozhnov, V V

2011-01-01

A noninvasive evaluation method of hypothalamo-pituitary-adrenals axis (HPA) activity in the Siberian tiger was verified. Comparison of the activity level of HPA in Siberian tigers in the wild and in captivity, and their alterations over the year was carried out. Significant seasonal deviations between activity levels of HPA in tigers in captivity were not found. In the wild, this level was significantly higher, reaching the maximum from November to January, which can be related with an unfavorable influence on tigers in low temperatures and deep snow cover.

Subjective rating scales as a workload

NASA Technical Reports Server (NTRS)

Bird, K. L.

1981-01-01

A multidimensional bipolar-adjective rating scale is employed as a subjective measure of operator workload in the performance of a one-axis tracking task. The rating scale addressed several dimensions of workload, including cognitive, physical, and perceptual task loading as well as fatigue and stress effects. Eight subjects performed a one-axis tracking task (with six levels of difficulty) and rated these tasks on several workload dimensions. Performance measures were tracking error RMS (root-mean square) and the standard deviation of control stick output. Significant relationships were observed between these performance measures and skill required, task complexity, attention level, task difficulty, task demands, and stress level.

Dynamical stability of the one-dimensional rigid Brownian rotator: the role of the rotator’s spatial size and shape

NASA Astrophysics Data System (ADS)

Jeknić-Dugić, Jasmina; Petrović, Igor; Arsenijević, Momir; Dugić, Miroljub

2018-05-01

We investigate dynamical stability of a single propeller-like shaped molecular cogwheel modelled as the fixed-axis rigid rotator. In the realistic situations, rotation of the finite-size cogwheel is subject to the environmentally-induced Brownian-motion effect that we describe by utilizing the quantum Caldeira-Leggett master equation. Assuming the initially narrow (classical-like) standard deviations for the angle and the angular momentum of the rotator, we investigate the dynamics of the first and second moments depending on the size, i.e. on the number of blades of both the free rotator as well as of the rotator in the external harmonic field. The larger the standard deviations, the less stable (i.e. less predictable) rotation. We detect the absence of the simple and straightforward rules for utilizing the rotator’s stability. Instead, a number of the size-related criteria appear whose combinations may provide the optimal rules for the rotator dynamical stability and possibly control. In the realistic situations, the quantum-mechanical corrections, albeit individually small, may effectively prove non-negligible, and also revealing subtlety of the transition from the quantum to the classical dynamics of the rotator. As to the latter, we detect a strong size-dependence of the transition to the classical dynamics beyond the quantum decoherence process.

[The accuracy of palpation from orientation points for the navigated implantation of knee prostheses].

PubMed

Fuiko, R; Kotten, B; Zettl, R; Ritschl, P

2004-03-01

Cinematic and pointing procedures are used for non-image based navigated implantation during total knee replacement. Pointing procedures require an exact knowledge of the landmarks. In this anatomical study, landmarks are defined and repeatedly referenced. Precision and reproducibility are evaluated by means of an inter- and an intra-observer study. The axes of the femur and tibia are calculated using the landmarks. The specific landmarks of 30 femurs and 27 tibias were palpated by three surgeons and digitised by means of a photogrammetric system, as used intra-operatively. The recorded data were statistically evaluated. The specific landmarks can be referenced with great precision. The vectors that influence the implant position show a mean femoral deviation of 0.9 mm and a mean tibial deviation of 1.0 mm. The repeating accuracy of every observer was 1.5 mm femoral and 1.0 mm tibial. The calculated long axes at the femur and tibia thus reach a precision of 0.1 degrees (min.-max.: 0-0.9 degrees) at the femur and 0.2 degrees (.0-1.1 degrees) at the tibia. The short axes at the distal femur and proximal tibia exhibit an average deviation of from 0.7 degrees to 1.9 degrees (0-11.3 degrees). Long axes (mechanical axes) can be determined exactly but the precision of the short axes (rotational axes) is unsatisfactory, although palpation of landmarks was accurate. Therefore, palpation of more than one rotational axis at the femur and tibia is mandatory and should be visualized on the monitor during surgery.

Mutations causing syndromic autism define an axis of synaptic pathophysiology.

PubMed

Auerbach, Benjamin D; Osterweil, Emily K; Bear, Mark F

2011-11-23

Tuberous sclerosis complex and fragile X syndrome are genetic diseases characterized by intellectual disability and autism. Because both syndromes are caused by mutations in genes that regulate protein synthesis in neurons, it has been hypothesized that excessive protein synthesis is one core pathophysiological mechanism of intellectual disability and autism. Using electrophysiological and biochemical assays of neuronal protein synthesis in the hippocampus of Tsc2(+/-) and Fmr1(-/y) mice, here we show that synaptic dysfunction caused by these mutations actually falls at opposite ends of a physiological spectrum. Synaptic, biochemical and cognitive defects in these mutants are corrected by treatments that modulate metabotropic glutamate receptor 5 in opposite directions, and deficits in the mutants disappear when the mice are bred to carry both mutations. Thus, normal synaptic plasticity and cognition occur within an optimal range of metabotropic glutamate-receptor-mediated protein synthesis, and deviations in either direction can lead to shared behavioural impairments.

Spatial and temporal variations of the ion velocity measured in the Venus ionosphere

NASA Technical Reports Server (NTRS)

Miller, K. L.; Knudsen, W. C.

1987-01-01

Temporal and spatial deviations of ion velocity from the dominant flow of the Venusian ionosphere were detected in data collected from a retarding potential analyzer (RPA) aboard the Pioneer-Venus orbiter spectrometer. The ion velocity measurements were analyzed for the first 3.5 Venus years of the Pioneer-Venus mission, approximately through orbit 780. The deviations of ion velocity from the dominant velocity of the Venusian ionosphere, which generally flows nightward and is almost symmetric about the sun-Venus axis, affect both the ionospheric structure and dynamics. Two examples of departure from steady symmetric flow that were measured by the RPA are discussed.

The sulcus line of the trochlear groove is more accurate than Whiteside's Line in determining femoral component rotation.

PubMed

Talbot, Simon; Dimitriou, Pandelis; Radic, Ross; Zordan, Rachel; Bartlett, John

2015-11-01

The sulcus line (SL) is a three-dimensional curve produced from multiple points along the trochlear groove. Whiteside's Line, also known as the anteroposterior axis (APA), is derived from single anterior and posterior points. The purposes of the two studies presented in this paper are to (1) assess the results from the clinical use of the SL in a large clinical series, (2) measure the SL and the APA on three-dimensional CT reconstructions, (3) demonstrate the effect of parallax error on the use of the APA and (4) determine the accuracy of an axis derived by combining the SL and the posterior condylar axis (PCA). In the first study, we assessed the SL using a large, single surgeon series of consecutive patients undergoing primary total knee arthroplasties. The post-operative CT scans of patients (n = 200) were examined to determine the final rotational alignment of the femoral component. In the second study, measurements were taken in a series of 3DCT reconstructions of osteoarthritic knees (n = 44). The mean position of the femoral component in the clinical series was 0.6° externally rotated to the surgical epicondylar axis, with a standard deviation of 2.9° (ranges from -7.2° to 6.7°). On the 3DCT reconstructions, the APA (88.2° ± 4.2°) had significantly higher variance than the SL (90.3° ± 2.7°) (F = 5.82 and p = 0.017). An axis derived by averaging the SL and the PCA+3° produced a significant decrease in both the number of outliers (p = 0.03 vs. PCA and p = 0.007 vs. SL) and the variance (F = 6.15 and p = 0.015 vs. SL). The coronal alignment of the SL varied widely relative to the mechanical axis (0.4° ± 3.8°) and the distal condylar surface (2.6° ± 4.3°). The multiple points used to determine the SL confer anatomical and geometrical advantages, and therefore, it should be considered a separate rotational landmark to the APA. These findings may explain the high degree of variability in the measurement of the APA which is documented in the literature. Combining a geometrically correct SL and the PCA is likely to further improve accuracy.

A Miniature Magnetic-Force-Based Three-Axis AC Magnetic Sensor with Piezoelectric/Vibrational Energy-Harvesting Functions.

PubMed

Hung, Chiao-Fang; Yeh, Po-Chen; Chung, Tien-Kan

2017-02-08

In this paper, we demonstrate a miniature magnetic-force-based, three-axis, AC magnetic sensor with piezoelectric/vibrational energy-harvesting functions. For magnetic sensing, the sensor employs a magnetic-mechanical-piezoelectric configuration (which uses magnetic force and torque, a compact, single, mechanical mechanism, and the piezoelectric effect) to convert x -axis and y -axis in-plane and z -axis magnetic fields into piezoelectric voltage outputs. Under the x -axis magnetic field (sine-wave, 100 Hz, 0.2-3.2 gauss) and the z -axis magnetic field (sine-wave, 142 Hz, 0.2-3.2 gauss), the voltage output with the sensitivity of the sensor are 1.13-26.15 mV with 8.79 mV/gauss and 1.31-8.92 mV with 2.63 mV/gauss, respectively. In addition, through this configuration, the sensor can harness ambient vibrational energy, i.e., possessing piezoelectric/vibrational energy-harvesting functions. Under x -axis vibration (sine-wave, 100 Hz, 3.5 g) and z -axis vibration (sine-wave, 142 Hz, 3.8 g), the root-mean-square voltage output with power output of the sensor is 439 mV with 0.333 μW and 138 mV with 0.051 μW, respectively. These results show that the sensor, using this configuration, successfully achieves three-axis magnetic field sensing and three-axis vibration energy-harvesting. Due to these features, the three-axis AC magnetic sensor could be an important design reference in order to develop future three-axis AC magnetic sensors, which possess energy-harvesting functions, for practical industrial applications, such as intelligent vehicle/traffic monitoring, processes monitoring, security systems, and so on.

Experimental Study on the Axis Line Deflection of Ti6A14V Titanium Alloy in Gun-Drilling Process

NASA Astrophysics Data System (ADS)

Li, Liang; Xue, Hu; Wu, Peng

2018-01-01

Titanium alloy is widely used in aerospace industry, but it is also a typical difficult-to-cut material. During Deep hole drilling of the shaft parts of a certain large aircraft, there are problems of bad surface roughness, chip control and axis deviation, so experiments on gun-drilling of Ti6A14V titanium alloy were carried out to measure the axis line deflection, diameter error and surface integrity, and the reasons of these errors were analyzed. Then, the optimized process parameter was obtained during gun-drilling of Ti6A14V titanium alloy with deep hole diameter of 17mm. Finally, we finished the deep hole drilling of 860mm while the comprehensive error is smaller than 0.2mm and the surface roughness is less than 1.6μm.

Attenuation and image noise level based online z-axis tube current modulation for CT scans independent with localizer radiograph: simulation study and results

NASA Astrophysics Data System (ADS)

Tian, Yi; Chen, Mahao; Kong, Jun

2009-02-01

With the online z-axis tube current modulation (OZTCM) technique proposed by this work, full automatic exposure control (AEC) for CT systems could be realized with online feedback not only for angular tube current modulation (TCM) but also for z-axis TCM either. Then the localizer radiograph was not required for TCM any more. OZTCM could be implemented with 2 schemes as attenuation based μ-OZTCM and image noise level based μ-OZTCM. Respectively the maximum attenuation of projection readings and standard deviation of reconstructed images can be used to modulate the tube current level in z-axis adaptively for each half (180 degree) or full (360 degree) rotation. Simulation results showed that OZTCM achieved better noise level than constant tube current scan case by using same total dose in mAs. The OZTCM can provide optimized base tube current level for angular TCM to realize an effective auto exposure control when localizer radiograph is not available or need to be skipped for simplified scan protocol in case of emergency procedure or children scan, etc.

A Nonlinear Calibration Algorithm Based on Harmonic Decomposition for Two-Axis Fluxgate Sensors

PubMed Central

Liu, Shibin

2018-01-01

Nonlinearity is a prominent limitation to the calibration performance for two-axis fluxgate sensors. In this paper, a novel nonlinear calibration algorithm taking into account the nonlinearity of errors is proposed. In order to establish the nonlinear calibration model, the combined effort of all time-invariant errors is analyzed in detail, and then harmonic decomposition method is utilized to estimate the compensation coefficients. Meanwhile, the proposed nonlinear calibration algorithm is validated and compared with a classical calibration algorithm by experiments. The experimental results show that, after the nonlinear calibration, the maximum deviation of magnetic field magnitude is decreased from 1302 nT to 30 nT, which is smaller than 81 nT after the classical calibration. Furthermore, for the two-axis fluxgate sensor used as magnetic compass, the maximum error of heading is corrected from 1.86° to 0.07°, which is approximately 11% in contrast with 0.62° after the classical calibration. The results suggest an effective way to improve the calibration performance of two-axis fluxgate sensors. PMID:29789448

Comparison of the iAssist Handheld Guidance System to Conventional Instruments for Mechanical Axis Restoration in Total Knee Arthroplasty.

PubMed

Kinney, Matthew C; Cidambi, Krishna R; Severns, Dustyn L; Gonzales, Francis B

2018-01-01

Recent advances in total knee arthroplasty (TKA) include an intelligent instrument system designed to provide intraoperative guidance to reduce mechanical alignment errors. Internal position-sensing technology is integrated into microelectronic pods that attach to cutting blocks. The purpose of this prospective, randomized study was to determine whether this iAssist system enables the surgeon to make more accurate bone resections and better restore the mechanical axis compared to conventional instruments in TKA. We randomized patients undergoing TKA into 2 groups. Group I (n = 25) underwent TKA assisted by the iAssist guidance system, group II (n = 25) underwent TKA using conventional instruments. Preoperative and postoperative mechanical axes were measured from full-length lower extremity radiographs to evaluate alignment. Additional surgical parameters were also assessed, including tourniquet time and blood loss. Patient demographics and preoperative mechanical axis alignments were similar between the groups. Postoperatively, 4.0% of patients had greater than 3° of tibial or femoral component mal-alignment in the guidance-assisted cohort, compared with 36.0% in the conventional group (P < .05). Additionally, group I showed significant improvement in variance seen in both the femoral mechanical axis (1.65° ± 0.17° vs 2.23° ± 0.33°, P < .005) and tibial mechanical axis (1.28° ± 0.13° vs 1.71° ± 0.24°, P < .005) compared to group II. There were no significant differences in tourniquet time (P = .86) or blood loss (P = .39) between groups. Use of the iAssist system in TKA results in an improved postoperative mechanical axis and decreased alignment variability compared to conventional instruments, without significantly increasing operative time. Copyright © 2017 Elsevier Inc. All rights reserved.

Design of a gait training device for control of pelvic obliquity.

PubMed

Pietrusinski, Maciej; Severini, Giacomo; Cajigas, Iahn; Mavroidis, Constantinos; Bonato, Paolo

2012-01-01

This paper presents the design and testing of a novel device for the control of pelvic obliquity during gait. The device, called the Robotic Gait Rehabilitation (RGR) Trainer, consists of a single actuator system designed to target secondary gait deviations, such as hip-hiking, affecting the movement of the pelvis. Secondary gait deviations affecting the pelvis are generated in response to primary gait deviations (e.g. limited knee flexion during the swing phase) in stroke survivors and contribute to the overall asymmetrical gait pattern often observed in these patients. The proposed device generates a force field able to affect the obliquity of the pelvis (i.e. the rotation of the pelvis around the anteroposterior axis) by using an impedance controlled single linear actuator acting on a hip orthosis. Tests showed that the RGR Trainer is able to induce changes in pelvic obliquity trajectories (hip-hiking) in healthy subjects. These results suggest that the RGR Trainer is suitable to test the hypothesis that has motivated our efforts toward developing the system, namely that addressing both primary and secondary gait deviations during robotic-assisted gait training may help promote a physiologically-sound gait behavior more effectively than when only primary deviations are addressed.

Freeform solar concentrator with a highly asymmetric acceptance cone

NASA Astrophysics Data System (ADS)

Wheelwright, Brian; Angel, J. Roger P.; Coughenour, Blake; Hammer, Kimberly

2014-10-01

A solar concentrator with a highly asymmetric acceptance cone is investigated. Concentrating photovoltaic systems require dual-axis sun tracking to maintain nominal concentration throughout the day. In addition to collecting direct rays from the solar disk, which subtends ~0.53 degrees, concentrating optics must allow for in-field tracking errors due to mechanical misalignment of the module, wind loading, and control loop biases. The angular range over which the concentrator maintains <90% of on-axis throughput is defined as the optical acceptance angle. Concentrators with substantial rotational symmetry likewise exhibit rotationally symmetric acceptance angles. In the field, this is sometimes a poor match with azimuth-elevation trackers, which have inherently asymmetric tracking performance. Pedestal-mounted trackers with low torsional stiffness about the vertical axis have better elevation tracking than azimuthal tracking. Conversely, trackers which rotate on large-footprint circular tracks are often limited by elevation tracking performance. We show that a line-focus concentrator, composed of a parabolic trough primary reflector and freeform refractive secondary, can be tailored to have a highly asymmetric acceptance angle. The design is suitable for a tracker with excellent tracking accuracy in the elevation direction, and poor accuracy in the azimuthal direction. In the 1000X design given, when trough optical errors (2mrad rms slope deviation) are accounted for, the azimuthal acceptance angle is +/- 1.65°, while the elevation acceptance angle is only +/-0.29°. This acceptance angle does not include the angular width of the sun, which consumes nearly all of the elevation tolerance at this concentration level. By decreasing the average concentration, the elevation acceptance angle can be increased. This is well-suited for a pedestal alt-azimuth tracker with a low cost slew bearing (without anti-backlash features).

Experimental study of a wake behind a barrier

NASA Astrophysics Data System (ADS)

Tomáš, Dufek; Katarína, Ratkovská

2017-09-01

This article describes in detail an experiment which was carried out on a wind tunnel in the Laboratory of the Department of Power Machines, Faculty of Mechanical Engineering, at the University of West Bohemia (UWB), using Particle Image Velocimetry and Stereo Particle Image Velocimetry. PIV is a non-invasive method that allows you to simultaneously measure the flow velocity across the entire field under investigation. In the experiment, the field was located behind the exit of the wind tunnel. The experiment dealt with the measurement of the wake behind a barrier. Measurement with Stereo PIV was carried out in several vertical parallel planes perpendicular to the axis of the tunnel. Conventional PIV method was then used for a horizontal plane passing through the axis of the tunnel at half the height of the barrier. The velocities in the measured plane are expressed by a vector map. In areas not affected by the wake, the speed in the w direction is about 16 m / s. The wake is formed behind the barrier. A shear layer is formed at the boundary between the flowing air and the braked air. A backflow occurs in the area just behind the barrier. The highest speed in the area is achieved in places just behind the exit of the tunnel, where the current is not affected by the barrier. In the direction from the axis and the obstacle, the speed gradually rises from the negative values of the return flow through the zero speed. In addition to the velocity fields, the output from the experimental measurement was also the distribution of the sum of variances, standard deviation and correlation coefficient in the measured planes.

Sex differences in early-life programming of the hypothalamic-pituitary-adrenal axis in humans.

PubMed

Gifford, Robert M; Reynolds, Rebecca M

2017-11-01

Increasing evidence supports fetal glucocorticoid exposure with associated altered offspring hypothalamic-pituitary-adrenal (HPA) axis activity as a key mechanism linking early life events with later life disease. Alterations in HPA axis activity are linked to a range of cardiometabolic and psychiatric diseases. As many of these diseases manifest sex differences in presentation we review the evidence for programmed sex-differences in the HPA axis. Available literature suggests vulnerability of the female HPA axis to prenatal stressors with female offspring demonstrating increased HPA axis reactivity. This may be due to changes in placental glucocorticoid metabolism leading to increased fetal glucocorticoid exposure. We discuss the potential consequences of increased vulnerability of the female HPA axis for later life health and consider the underlying mechanisms. Further studies are needed to determine whether sex-differences in early-life programming of the HPA axis represent a pathway underpinning the sex-differences in common cardiometabolic and psychiatric diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Meinke, Rainer

A method for manufacture of a conductor assembly. The assembly is of the type which, when conducting current, generates a magnetic field or in which, in the presence of a changing magnetic field, a voltage is induced. In an example embodiment one or more first coil rows are formed. The assembly has multiple coil rows about an axis with outer coil rows formed about inner coil rows. A determination is made of deviations from specifications associated with the formed one or more first coil rows. One or more deviations correspond to a magnitude of a multipole field component which departsmore » from a field specification. Based on the deviations, one or more wiring patterns are generated for one or more second coil rows to be formed about the one or more first coil rows. The one or more second coil rows are formed in the assembly. The magnitude of each multipole field component that departs from the field specification is offset.« less

Onorbit IMU alignment error budget

NASA Technical Reports Server (NTRS)

Corson, R. W.

1980-01-01

The Star Tracker, Crew Optical Alignment Sight (COAS), and Inertial Measurement Unit (IMU) from a complex navigation system with a multitude of error sources were combined. A complete list of the system errors is presented. The errors were combined in a rational way to yield an estimate of the IMU alignment accuracy for STS-1. The expected standard deviation in the IMU alignment error for STS-1 type alignments was determined to be 72 arc seconds per axis for star tracker alignments and 188 arc seconds per axis for COAS alignments. These estimates are based on current knowledge of the star tracker, COAS, IMU, and navigation base error specifications, and were partially verified by preliminary Monte Carlo analysis.

SU-E-T-313: Dosimetric Deviation of Misaligned Beams for a 6 MV Photon Linear Accelerator Using Monte Carlo Simulations

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

Kim, S

2015-06-15

Purpose: To quantify the dosimetric variations of misaligned beams for a linear accelerator by using Monte Carlo (MC) simulations. Method and Materials: Misaligned beams of a Varian 21EX Clinac were simulated to estimate the dosimetric effects. All the linac head components for a 6 MV photon beam were implemented in BEAMnrc/EGSnrc system. For incident electron beam parameters, 6 MeV with 0.1 cm full-width-half-max Gaussian beam was used. A phase space file was obtained below the jaw per each misalignment condition of the incident electron beam: (1) The incident electron beams were tilted by 0.5, 1.0 and 1.5 degrees on themore » x-axis from the central axis. (2) The center of the incident electron beam was off-axially moved toward +x-axis by 0.1, 0.2, and 0.3 cm away from the central axis. Lateral profiles for each misaligned beam condition were acquired at dmax = 1.5 cm and 10 cm depth in a rectangular water phantom. Beam flatness and symmetry were calculated by using the lateral profile data. Results: The lateral profiles were found to be skewed opposite to the angle of the incident beam for the tilted beams. For the displaced beams, similar skewed lateral profiles were obtained with small shifts of penumbra on the +x-axis. The variations of beam flatness were 3.89–11.18% and 4.12–42.57% for the tilted beam and the translated beam, respectively. The beam symmetry was separately found to be 2.95 −9.93% and 2.55–38.06% separately. It was found that the percent increase of the flatness and the symmetry values are approximated 2 to 3% per 0.5 degree tilt or per 1 mm displacement. Conclusion: This study quantified the dosimetric effects of misaligned beams using MC simulations. The results would be useful to understand the magnitude of the dosimetric deviations for the misaligned beams.« less

Improved particle position accuracy from off-axis holograms using a Chebyshev model.

PubMed

Öhman, Johan; Sjödahl, Mikael

2018-01-01

Side scattered light from micrometer-sized particles is recorded using an off-axis digital holographic setup. From holograms, a volume is reconstructed with information about both intensity and phase. Finding particle positions is non-trivial, since poor axial resolution elongates particles in the reconstruction. To overcome this problem, the reconstructed wavefront around a particle is used to find the axial position. The method is based on the change in the sign of the curvature around the true particle position plane. The wavefront curvature is directly linked to the phase response in the reconstruction. In this paper we propose a new method of estimating the curvature based on a parametric model. The model is based on Chebyshev polynomials and is fit to the phase anomaly and compared to a plane wave in the reconstructed volume. From the model coefficients, it is possible to find particle locations. Simulated results show increased performance in the presence of noise, compared to the use of finite difference methods. The standard deviation is decreased from 3-39 μm to 6-10 μm for varying noise levels. Experimental results show a corresponding improvement where the standard deviation is decreased from 18 μm to 13 μm.

Off-axis mirror fabrication from spherical surfaces under mechanical stress

NASA Astrophysics Data System (ADS)

Izazaga-Pérez, R.; Aguirre-Aguirre, D.; Percino-Zacarías, M. E.; Granados-Agustín, Fermin-Salomon

2013-09-01

The preliminary results in the fabrication of off-axis optical surfaces are presented. The propose using the conventional polishing method and with the surface under mechanical stress at its edges. It starts fabricating a spherical surface using ZERODUR® optical glass with the conventional polishing method, the surface is deformed by applying tension and/or compression at the surface edges using a specially designed mechanical mount. To know the necessary deformation, the interferogram of the deformed surface is analyzed in real time with a ZYGO® Mark II Fizeau type interferometer, the mechanical stress is applied until obtain the inverse interferogram associated to the off-axis surface that we need to fabricate. Polishing process is carried out again until obtain a spherical surface, then mechanical stress in the edges are removed and compares the actual interferogram with the theoretical associated to the off-axis surface. To analyze the resulting interferograms of the surface we used the phase shifting analysis method by using a piezoelectric phase-shifter and Durango® interferometry software from Diffraction International™.

High mobility vehicle

NASA Technical Reports Server (NTRS)

Wilcox, Brian H. (Inventor); Nasif, Annette K. (Inventor)

2001-01-01

A vehicle, for driving over a ground surface, has a body with a left side, a right side, a front and a back. The vehicle includes left and right drive mechanisms. Each mechanism includes first and second traction elements for engaging the ground surface and transmitting a driving force between the vehicle and ground surface. Each mechanism includes first and second arms coupled to the first and second traction elements for relative rotation about first and second axis respectively. Each mechanism includes a rotor having a third axis, the rotor coupled to the body for rotation about the third axis and coupled to the first and second arms for relative rotation about the third axis. The mechanism includes first and second drive motors for driving the first and second traction elements and first and second transmissions, driven by the first and second motors and engaging the rotor. Driving the first and second traction elements simultaneously rotates the rotor relative to the first and second arms, respectively.

Motor mechanisms of vertical fusion in individuals with superior oblique paresis.

PubMed

Mudgil, Ananth V; Walker, Mark; Steffen, Heimo; Guyton, David L; Zee, David S

2002-06-01

We wanted to determine the mechanisms of motor vertical fusion in patients with superior oblique paresis and to correlate these mechanisms with surgical outcomes. Ten patients with superior oblique paresis underwent 3-axis, bilateral, scleral search coil eye movement recordings. Eye movements associated with fusion were analyzed. Six patients had decompensated congenital superior oblique paresis and 4 had acquired superior oblique paresis. All patients with acquired superior oblique paresis relied predominantly on the vertical rectus muscles for motor fusion. Patients with congenital superior oblique paresis were less uniform in their mechanisms for motor fusion: 2 patients used predominantly the oblique muscles, 2 patients used predominantly the vertical recti, and 2 patients used predominantly the superior oblique in the hyperdeviated eye and the superior rectus in the hypodeviated eye. The last 2 patients developed the largest changes in torsional eye alignment relative to changes in vertical eye alignment and were the only patients to develop symptomatic surgical overcorrections. There are 3 different mechanisms for vertical fusion in individuals with superior oblique paresis, with the predominant mechanism being the vertical recti. A subset of patients with superior oblique paresis uses predominantly the superior oblique muscle in the hyperdeviated paretic eye and the superior rectus muscle in the fellow eye for fusion. This results in intorsion of both eyes, causing a large change in torsional alignment. The consequent cyclodisparity, in addition to the existing vertical deviation, may make fusion difficult. The differing patterns of vertical fusional vergence may have implications for surgical treatment.

Rib kinematics during lung ventilation in the American alligator (Alligator mississippiensis): an XROMM analysis

PubMed Central

Moritz, Sabine; Codd, Jonathan; Sellers, William I.

2017-01-01

ABSTRACT The current hypothesis regarding the mechanics of breathing in crocodylians is that the double-headed ribs, with both a capitulum and tuberculum, rotate about a constrained axis passing through the two articulations; moreover, this axis shifts in the caudal thoracic ribs, as the vertebral parapophysis moves from the centrum to the transverse process. Additionally, the ventral ribcage in crocodylians is thought to possess additional degrees of freedom through mobile intermediate ribs. In this study, X-ray reconstruction of moving morphology (XROMM) was used to quantify rib rotation during breathing in American alligators. Whilst costovertebral joint anatomy predicted overall patterns of motion across the ribcage (decreased bucket handle motion and increased calliper motion), there were significant deviations: anatomical axes overestimated pump handle motion and, generally, ribs in vivo rotate about all three body axes more equally than predicted. The intermediate ribs are mobile, with a high degree of rotation measured about the dorsal intracostal joints, especially in the more caudal ribs. Motion of the sternal ribs became increasingly complex caudally, owing to a combination of the movements of the vertebral and intermediate segments. As the crocodylian ribcage is sometimes used as a model for the ancestral archosaur, these results have important implications for how rib motion is reconstructed in fossil taxa, and illustrate the difficulties in reconstructing rib movement based on osteology alone. PMID:28855323

From solid solution to cluster formation of Fe and Cr in α-Zr

NASA Astrophysics Data System (ADS)

Burr, P. A.; Wenman, M. R.; Gault, B.; Moody, M. P.; Ivermark, M.; Rushton, M. J. D.; Preuss, M.; Edwards, L.; Grimes, R. W.

2015-12-01

To understand the mechanisms by which the re-solution of Fe and Cr additions increase the corrosion rate of irradiated Zr alloys, the solubility and clustering of Fe and Cr in model binary Zr alloys was investigated using a combination of experimental and modelling techniques - atom probe tomography (APT), x-ray diffraction (XRD), thermoelectric power (TEP) and density functional theory (DFT). Cr occupies both interstitial and substitutional sites in the α-Zr lattice; Fe favours interstitial sites, and a low-symmetry site that was not previously modelled is found to be the most favourable for Fe. Lattice expansion as a function of Fe and Cr content in the α-Zr matrix deviates from Vegard's law and is strongly anisotropic for Fe additions, expanding the c-axis while contracting the a-axis. Matrix content of solutes cannot be reliably estimated from lattice parameter measurements, instead a combination of TEP and APT was employed. Defect clusters form at higher solution concentrations, which induce a smaller lattice strain compared to the dilute defects. In the presence of a Zr vacancy, all two-atom clusters are more soluble than individual point defects and as many as four Fe or three Cr atoms could be accommodated in a single Zr vacancy. The Zr vacancy is critical for the increased apparent solubility of defect clusters; the implications for irradiation induced microstructure changes in Zr alloys are discussed.

A Correlational Study of Scoliosis and Trunk Balance in Adult Patients with Mandibular Deviation

PubMed Central

Yang, Yang; Wang, Na; Wang, Wenyong; Ding, Yin; Sun, Shiyao

2013-01-01

Previous studies have confirmed that patients with mandibular deviation often have abnormal morphology of their cervical vertebrae. However, the relationship between mandibular deviation, scoliosis, and trunk balance has not been studied. Currently, mandibular deviation is usually treated as a single pathology, which leads to poor clinical efficiency. We investigated the relationship of spine coronal morphology and trunk balance in adult patients with mandibular deviation, and compared the finding to those in healthy volunteers. 35 adult patients with skeletal mandibular deviation and 10 healthy volunteers underwent anterior X-ray films of the head and posteroanterior X-ray films of the spine. Landmarks and lines were drawn and measured on these films. The axis distance method was used to measure the degree of scoliosis and the balance angle method was used to measure trunk balance. The relationship of mandibular deviation, spine coronal morphology and trunk balance was evaluated with the Pearson correlation method. The spine coronal morphology of patients with mandibular deviation demonstrated an “S” type curve, while a straight line parallel with the gravity line was found in the control group (significant difference, p<0.01). The trunk balance of patients with mandibular deviation was disturbed (imbalance angle >1°), while the control group had a normal trunk balance (imbalance angle <1°). There was a significant difference between the two groups (p<0.01). The degree of scoliosis and shoulder imbalance correlated with the degree of mandibular deviation, and presented a linear trend. The direction of mandibular deviation was the same as that of the lateral bending of thoracolumbar vertebrae, which was opposite to the direction of lateral bending of cervical vertebrae. Our study shows the degree of mandibular deviation has a high correlation with the degree of scoliosis and trunk imbalance, all the three deformities should be clinically evaluated in the management of mandibular deviation. PMID:23555836

Intra-fraction motion of larynx radiotherapy

NASA Astrophysics Data System (ADS)

Durmus, Ismail Faruk; Tas, Bora

2018-02-01

In early stage laryngeal radiotherapy, movement is an important factor. Thyroid cartilage can move from swallowing, breathing, sound and reflexes. The effects of this motion on the target volume (PTV) during treatment were examined. In our study, the target volume movement during the treatment for this purpose was examined. Thus, setup margins are re-evaluated and patient-based PTV margins are determined. Intrafraction CBCT was scanned in 246 fractions for 14 patients. During the treatment, the amount of deviation which could be lateral, vertical and longitudinal axis was determined. ≤ ± 0.1cm deviation; 237 fractions in the lateral direction, 202 fractions in the longitudinal direction, 185 fractions in the vertical direction. The maximum deviation values were found in the longitudinal direction. Intrafraction guide in laryngeal radiotherapy; we are sure of the correctness of the treatment, the target volume is to adjust the margin and dose more precisely, we control the maximum deviation of the target volume for each fraction. Although the image quality of intrafraction-CBCT scans was lower than the image quality of planning CT, they showed sufficient contrast for this work.

Balancing with Vibration: A Prelude for “Drift and Act” Balance Control

PubMed Central

Milton, John G.; Ohira, Toru; Cabrera, Juan Luis; Fraiser, Ryan M.; Gyorffy, Janelle B.; Ruiz, Ferrin K.; Strauss, Meredith A.; Balch, Elizabeth C.; Marin, Pedro J.; Alexander, Jeffrey L.

2009-01-01

Stick balancing at the fingertip is a powerful paradigm for the study of the control of human balance. Here we show that the mean stick balancing time is increased by about two-fold when a subject stands on a vibrating platform that produces vertical vibrations at the fingertip (0.001 m, 15–50 Hz). High speed motion capture measurements in three dimensions demonstrate that vibration does not shorten the neural latency for stick balancing or change the distribution of the changes in speed made by the fingertip during stick balancing, but does decrease the amplitude of the fluctuations in the relative positions of the fingertip and the tip of the stick in the horizontal plane, A(x,y). The findings are interpreted in terms of a time-delayed “drift and act” control mechanism in which controlling movements are made only when controlled variables exceed a threshold, i.e. the stick survival time measures the time to cross a threshold. The amplitude of the oscillations produced by this mechanism can be decreased by parametric excitation. It is shown that a plot of the logarithm of the vibration-induced increase in stick balancing skill, a measure of the mean first passage time, versus the standard deviation of the A(x,y) fluctuations, a measure of the distance to the threshold, is linear as expected for the times to cross a threshold in a stochastic dynamical system. These observations suggest that the balanced state represents a complex time–dependent state which is situated in a basin of attraction that is of the same order of size. The fact that vibration amplitude can benefit balance control raises the possibility of minimizing risk of falling through appropriate changes in the design of footwear and roughness of the walking surfaces. PMID:19841741

Characterization for elastic constants of fused deposition modelling-fabricated materials based on the virtual fields method and digital image correlation

NASA Astrophysics Data System (ADS)

Cao, Quankun; Xie, Huimin

2017-12-01

Fused deposition modelling (FDM), a widely used rapid prototyping process, is a promising technique in manufacturing engineering. In this work, a method for characterizing elastic constants of FDM-fabricated materials is proposed. First of all, according to the manufacturing process of FDM, orthotropic constitutive model is used to describe the mechanical behavior. Then the virtual fields method (VFM) is applied to characterize all the mechanical parameters (Q_{11}, Q_{22}, Q_{12}, Q_{66}) using the full-field strain, which is measured by digital image correlation (DIC). Since the principal axis of the FDM-fabricated structure is sometimes unknown due to the complexity of the manufacturing process, a disk in diametrical compression is used as the load configuration so that the loading angle can be changed conveniently. To verify the feasibility of the proposed method, finite element method (FEM) simulation is conducted to obtain the strain field of the disk. The simulation results show that higher accuracy can be achieved when the loading angle is close to 30°. Finally, a disk fabricated by FDM was used for the experiment. By rotating the disk, several tests with different loading angles were conducted. To determine the position of the principal axis in each test, two groups of parameters (Q_{11}, Q_{22}, Q_{12}, Q_{66}) are calculated by two different groups of virtual fields. Then the corresponding loading angle can be determined by minimizing the deviation between two groups of the parameters. After that, the four constants (Q_{11}, Q_{22}, Q_{12}, Q_{66}) were determined from the test with an angle of 27°.

Research of misalignment between dithered ring laser gyro angle rate input axis and dither axis

NASA Astrophysics Data System (ADS)

Li, Geng; Wu, Wenqi; FAN, Zhenfang; LU, Guangfeng; Hu, Shaomin; Luo, Hui; Long, Xingwu

2014-12-01

The strap-down inertial navigation system (SINS), especially the SINS composed by dithered ring laser gyroscope (DRLG) is a kind of equipment, which providing high reliability and performance for moving vehicles. However, the mechanical dither which is used to eliminate the "Lock-In" effect can cause vibration disturbance to the INS and lead to dithering coupling problem in the inertial measurement unit (IMU) gyroscope triad, so its further application is limited. Among DRLG errors between the true gyro rotation rate and the measured rotation rate, the frequently considered one is the input axis misalignment between input reference axis which is perpendicular to the mounting surface and gyro angular rate input axis. But the misalignment angle between DRLG dither axis and gyro angular rate input axis is often ignored by researchers, which is amplified by dither coupling problem and that would lead to negative effects especially in high accuracy SINS. In order to study the problem more clearly, the concept of misalignment between DRLG dither axis and gyro angle rate input axis is researched. Considering the error of misalignment is of the order of 10-3 rad. or even smaller, the best way to measure it is using DRLG itself by means of an angle exciter as an auxiliary. In this paper, the concept of dither axis misalignment is explained explicitly firstly, based on this, the frequency of angle exciter is induced as reference parameter, when DRLG is mounted on the angle exciter in a certain angle, the projections of angle exciter rotation rate and mechanical oscillation rate on the gyro input axis are both sensed by DRLG. If the dither axis has misalignment error with the gyro input axis, there will be four major frequencies detected: the frequency of angle exciter, the dither mechanical frequency, sum and difference frequencies of the former two frequencies. Then the amplitude spectrum of DRLG output signal obtained by the using LabVIEW program. if there are only angle exciter and the dither mechanical frequencies, the misalignment may be too small to be detected, otherwise, the amplitude of the sum and difference frequencies will show the misalignment angle between the gyro angle rate input axis and the dither axis. Finally, some related parameters such as frequency and amplitude of the angle exciter and sample rate are calculated and the results are analyzed. The simulation and experiment result prove the effectiveness of the proposed method..

Horizontal EDNA miner

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

Justice, J.C.; Delli-Gatti, F.A.

1985-12-03

A mining machine is utilized for making original generally horizontal bores in coal seams, and for enlarging preexisting bores. A single cutting head is mounted for rotation about a first horizontal axis generally perpendicular to the dimension of elongation of the horizontal bore, and is pivotal about a second horizontal axis, parallel to the first axis, to change its cutting, vertical position within the bore. A non-rotatable body member, with side wall supports, is mounted posteriorly of the cutting head, and includes a conveyor mechanism and a power mechanism operatively connected to it. The machine can be sumped into amore » bore and then the cutting head rotated about the second axis to change the vertical position thereof, and then moved rearwardly, any cut material being continuously conveyed to the bore mouth by the conveyor mechanism. The amount of vertical movement during the pivoting action about the second axis is controlled in response to the automatic sensing of the thickness of the coal seam in which the machine operates.« less

Measuring Diameters Of Large Vessels

NASA Technical Reports Server (NTRS)

Currie, James R.; Kissel, Ralph R.; Oliver, Charles E.; Smith, Earnest C.; Redmon, John W., Sr.; Wallace, Charles C.; Swanson, Charles P.

1990-01-01

Computerized apparatus produces accurate results quickly. Apparatus measures diameter of tank or other large cylindrical vessel, without prior knowledge of exact location of cylindrical axis. Produces plot of inner circumference, estimate of true center of vessel, data on radius, diameter of best-fit circle, and negative and positive deviations of radius from circle at closely spaced points on circumference. Eliminates need for time-consuming and error-prone manual measurements.

Ankle-foot orthosis bending axis influences running mechanics.

PubMed

Russell Esposito, Elizabeth; Ranz, Ellyn C; Schmidtbauer, Kelly A; Neptune, Richard R; Wilken, Jason M

2017-07-01

Passive-dynamic ankle-foot orthoses (AFOs) are commonly prescribed to improve locomotion for people with lower limb musculoskeletal weakness. The clinical prescription and design process are typically qualitative and based on observational assessment and experience. Prior work examining the effect of AFO design characteristics generally excludes higher impact activities such as running, providing clinicians and researchers limited information to guide the development of objective prescription guidelines. The proximal location of the bending axis may directly influence energy storage and return and resulting running mechanics. The purpose of this study was to determine if the location of an AFO's bending axis influences running mechanics. Marker and force data were recorded as 12 participants with lower extremity weakness ran overground while wearing a passive-dynamic AFO with posterior struts manufactured with central (middle) and off-centered (high and low) bending axes. Lower extremity joint angles, moments, powers, and ground reaction forces were calculated and compared between limbs and across bending axis conditions. Bending axis produced relatively small but significant changes. Ankle range of motion increased as the bending axis shifted distally (p<0.003). Peak ankle power absorption was greater in the low axis than high (p=0.013), and peak power generation was greater in the low condition than middle or high conditions (p<0.009). Half of the participants preferred the middle bending axis, four preferred low and two preferred high. Overall, if greater ankle range of motion is tolerated, a low bending axis provides power and propulsive benefits during running, although individual preference and physical ability should also be considered. Published by Elsevier B.V.

Torsional deformity of apical vertebra in adolescent idiopathic scoliosis.

PubMed

Kotwicki, Tomasz; Napiontek, Marek

2002-01-01

CT scans of structural thoracic idiopathic scoliosis were reviewed in nine patients admitted to our department for scoliosis surgery. The apical vertebra scans were chosen and the following parameters were evaluated: 1) alpha angle formed by the axis of vertebra and the axis of spinous process 2) beta concave and beta convex angle between the spinous process and the left and right transverse process, respectively, 3) gamma concave and gamma convex angle between the axis of vertebra and the left and right transverse process, respectively, 4) the rotation angle to the sagittal plane. The constant deviation of the spinous process towards the convex side of the curve was observed. The vertebral body itself was distorted towards the concavity of the curve. The angle between the spinous process and the transverse process was smaller on the convex side of the curve. The torsional, intravertebral deformity of the apical vertebra was a factor acting in the direction opposite to the rotation, in the sense to reduce the deformity of the spine in idiopathic scoliosis.

Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

NASA Astrophysics Data System (ADS)

Wang, Tong; Puchtler, Tim J.; Patra, Saroj K.; Zhu, Tongtong; Ali, Muhammad; Badcock, Tom J.; Ding, Tao; Oliver, Rachel A.; Schulz, Stefan; Taylor, Robert A.

2017-07-01

We report the direct generation of linearly polarized single photons with a deterministic polarization axis in self-assembled quantum dots (QDs), achieved by the use of non-polar InGaN without complex device geometry engineering. Here, we present a comprehensive investigation of the polarization properties of these QDs and their origin with statistically significant experimental data and rigorous k·p modeling. The experimental study of 180 individual QDs allows us to compute an average polarization degree of 0.90, with a standard deviation of only 0.08. When coupled with theoretical insights, we show that these QDs are highly insensitive to size differences, shape anisotropies, and material content variations. Furthermore, 91% of the studied QDs exhibit a polarization axis along the crystal [1-100] axis, with the other 9% polarized orthogonal to this direction. These features give non-polar InGaN QDs unique advantages in polarization control over other materials, such as conventional polar nitride, InAs, or CdSe QDs. Hence, the ability to generate single photons with polarization control makes non-polar InGaN QDs highly attractive for quantum cryptography protocols.

The hypothalamic-pituitary-thyroid axis and biological rhythms: The discovery of TSH's unexpected role using animal models.

PubMed

Ikegami, Keisuke; Yoshimura, Takashi

2017-10-01

Thyroid hormones (TH) are important for development, growth, and metabolism. It is also clear that the synthesis and secretion of TH are regulated by the hypothalamic-pituitary-thyroid (HPT) axis. Animal models have helped advance our understanding of the roles and regulatory mechanisms of TH. The animals' bodies develop through coordinated timing of cell division and differentiation. Studies of frog metamorphosis led to the discovery of TH and their role in development. However, to adapt to rhythmic environmental changes, animals also developed various endocrine rhythms. Studies of rodents clarified the neural and molecular mechanisms underlying the circadian regulation of the HPT axis. Moreover, birds have a sophisticated seasonal adaptation mechanism, and recent studies of quail revealed unexpected roles for thyroid-stimulating hormone (TSH) and TH in the seasonal regulation of reproduction. Interestingly, this mechanism is conserved in mammals. Thus, we review how animal studies have shaped our general understanding of the HPT axis in relation to biological rhythms. Copyright © 2017 Elsevier Ltd. All rights reserved.

a Baseline for Upper Crustal Velocity Variations Along the East Pacific Rise

NASA Astrophysics Data System (ADS)

Kappus, Mary Elizabeth

Seismic measurements of the oceanic crust and theoretical models of its generation at mid-ocean ridges suggest several systematic variations in upper crustal velocity structure, but without constraints on the inherent variation in newly-formed crust these suggestions remain tentative. The Wide Aperture Profiles (WAPs) which form the database for this study have sufficient horizontal extent and resolution in the upper crust to establish a zero-age baseline. After assessing the adequacy of amplitude preservation in several tau - p transform methods we make a precise estimate of the velocity at the top of the crust from analysis of amplitudes in the tau - p domain. Along a 52-km segment we find less than 5% variation from 2.45 km/s. Velocity models of the uppermost crust are constructed using waveform inversion for both reflection and refraction arrivals. This method exploits the high quality of both primary and secondary phases and provides an objective process for iteratively improving trial models and for measuring misfit. The resulting models show remarkable homogeneity: on-axis variation is 5% or less within layers 2A and 2B, increasing to 10% at the sharp 2A/2B boundary. The extrusive volcanic layer is only 130 m thick along-axis and corresponds to the triangular -shaped neovolcanic zone. From this we infer that the sheeted dikes feeding the extrusive layer 2A come up to very shallow depths on axis. Along axis, a fourth-order deviation from axial linearity identified geochemically is observed as a small increase in thickness of the extrusive layer. Off -axis, the velocity increases only slightly to 2.49 km/s, while the thickness of the extrusives increases to 217 km and the variability in both parameters increases with distance from the ridge axis. In a separate section we present the first published analysis of seismic records of thunder. We calculate multi -taper spectra to determine the peak energy in the lightning bolt and apply time-dependent polarization analysis to determine the lightning propagation path. The peak energies of the intracloud lightning bolts are all infrasonic, but we show that this is not incompatible with the mechanism of thunder production by a rapidly heated gas channel as was previously thought. From polarization analysis we find the direction to the lightning bolt from a single station record, in several cases resolving a significant horizontal component to the lightning path.

Speed control system for an access gate

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

Bzorgi, Fariborz M

2012-03-20

An access control apparatus for an access gate. The access gate typically has a rotator that is configured to rotate around a rotator axis at a first variable speed in a forward direction. The access control apparatus may include a transmission that typically has an input element that is operatively connected to the rotator. The input element is generally configured to rotate at an input speed that is proportional to the first variable speed. The transmission typically also has an output element that has an output speed that is higher than the input speed. The input element and the outputmore » element may rotate around a common transmission axis. A retardation mechanism may be employed. The retardation mechanism is typically configured to rotate around a retardation mechanism axis. Generally the retardation mechanism is operatively connected to the output element of the transmission and is configured to retard motion of the access gate in the forward direction when the first variable speed is above a control-limit speed. In many embodiments the transmission axis and the retardation mechanism axis are substantially co-axial. Some embodiments include a freewheel/catch mechanism that has an input connection that is operatively connected to the rotator. The input connection may be configured to engage an output connection when the rotator is rotated at the first variable speed in a forward direction and configured for substantially unrestricted rotation when the rotator is rotated in a reverse direction opposite the forward direction. The input element of the transmission is typically operatively connected to the output connection of the freewheel/catch mechanism.« less

Influence of Moisture Content and Compression Axis on Physico-mechanical Properties of Shorea robusta Seeds

NASA Astrophysics Data System (ADS)

Shashikumar, C.; Pradhan, R. C.; Mishra, S.

2018-06-01

Shorea robusta (Sal) is mainly harvested and processed for its seed oil, which has diverse application in commercial food and non-food based industries. Before extraction of its oil, seeds undergo into various post-harvest unit operations. Physical and mechanical properties play an important role in the handling and other processing activity. In this study influence of moisture content and compression axis of sal seed on physico-mechanical properties were studied and their application are highlighted. The experiments were conducted at five different moisture levels of 6.38, 10.49, 13.63, 17.64, and 21.95% (d.b) at two different orientations. The first orientation is on major axis (LEN) of the seed, and the other orientation is on intermediate or minor axis (WID), which is right angle to the major axis. It was observed that 68% of sal seeds were of medium size group at initial moisture content of 10.49% (d.b). The mean length and width of sal seed was found to be 26.7 mm and 12.8 mm, respectively. It was found that values of hardness, deformation at hardness, deformation at hardness percentage and energy for rupture were higher in minor axis (WID) as compared to the major axis (LEN). The results provide necessary data that may be useful to engineers, scientists, industries in the design of a suitable post-harvest processing machine.

Influence of Moisture Content and Compression Axis on Physico-mechanical Properties of Shorea robusta Seeds

NASA Astrophysics Data System (ADS)

Shashikumar, C.; Pradhan, R. C.; Mishra, S.

2018-02-01

Shorea robusta (Sal) is mainly harvested and processed for its seed oil, which has diverse application in commercial food and non-food based industries. Before extraction of its oil, seeds undergo into various post-harvest unit operations. Physical and mechanical properties play an important role in the handling and other processing activity. In this study influence of moisture content and compression axis of sal seed on physico-mechanical properties were studied and their application are highlighted. The experiments were conducted at five different moisture levels of 6.38, 10.49, 13.63, 17.64, and 21.95% (d.b) at two different orientations. The first orientation is on major axis (LEN) of the seed, and the other orientation is on intermediate or minor axis (WID), which is right angle to the major axis. It was observed that 68% of sal seeds were of medium size group at initial moisture content of 10.49% (d.b). The mean length and width of sal seed was found to be 26.7 mm and 12.8 mm, respectively. It was found that values of hardness, deformation at hardness, deformation at hardness percentage and energy for rupture were higher in minor axis (WID) as compared to the major axis (LEN). The results provide necessary data that may be useful to engineers, scientists, industries in the design of a suitable post-harvest processing machine.

Low cycle fatigue of MAR-M 200 single crystals at 760 and 870 deg C

NASA Technical Reports Server (NTRS)

Milligan, W. W.; Jayaraman, N.; Bill, R. C.

1984-01-01

Fully reversed low cycle fatigue tests were conducted on single crystals of the nickel-base superalloys Mar-M 200 at 760 C and 870 C. At 760 C, planar slip (octahedral) lead to orientation-dependent strain hardening and cyclic lives. Multiple slip crystals strain hardened the most, resulting in relatively high stress ranges and low lives. Single slip crystals strain hardened the least, resulting in relatively low stress ranges and higher lives. A preferential crack initiation site which was related to slip plane geometry was observed in single slip orientated crystals. At 870 C, the trends were quite different, and the slip character was much more homogeneous. As the tensile axis orientation deviated from 001 , the stress ranges increased and the cyclic lives decreased. Two possible mechanisms were proposed to explain the behavior: one is based on Takeuchi and Kuramoto's cube cross-slip model, and the other is based on orientation-dependent creep rates.

Conventional versus computer-assisted technique for total knee arthroplasty: a minimum of 5-year follow-up of 200 patients in a prospective randomized comparative trial.

PubMed

Cip, Johannes; Widemschek, Mark; Luegmair, Matthias; Sheinkop, Mitchell B; Benesch, Thomas; Martin, Arno

2014-09-01

In the literature, studies of computer-assisted total knee arthroplasty (TKA) after mid-term period are not conclusive and long-term data are rare. In a prospective, randomized, comparative study 100 conventional TKAs (group REG) were compared with 100 computer-assisted TKAs (group NAV). Minimum follow-up was 5years. No difference in implant failure was found with 1.1% in group NAV versus 4.6% in group REG (P=0.368). Group NAV showed a significantly less mean deviation of mechanical limb axis (P=0.015), more TKAs (90% versus 81% in group REG) were within 3° varus/valgus and a higher tibial slope and lateral distal femoral angle (LDFA) accuracy was found (P≤0.034). Clinical investigational parameters showed no differences (P≥0.058). Insall and HSS score total were also higher in group NAV (P≤0.016). Copyright © 2014 Elsevier Inc. All rights reserved.

Automated cell tracking identifies mechanically oriented cell divisions during Drosophila axis elongation.

PubMed

Wang, Michael F Z; Hunter, Miranda V; Wang, Gang; McFaul, Christopher; Yip, Christopher M; Fernandez-Gonzalez, Rodrigo

2017-04-01

Embryos extend their anterior-posterior (AP) axis in a conserved process known as axis elongation. Drosophila axis elongation occurs in an epithelial monolayer, the germband, and is driven by cell intercalation, cell shape changes, and oriented cell divisions at the posterior germband. Anterior germband cells also divide during axis elongation. We developed image analysis and pattern-recognition methods to track dividing cells from confocal microscopy movies in a generally applicable approach. Mesectoderm cells, forming the ventral midline, divided parallel to the AP axis, while lateral cells displayed a uniform distribution of division orientations. Mesectoderm cells did not intercalate and sustained increased AP strain before cell division. After division, mesectoderm cell density increased along the AP axis, thus relieving strain. We used laser ablation to isolate mesectoderm cells from the influence of other tissues. Uncoupling the mesectoderm from intercalating cells did not affect cell division orientation. Conversely, separating the mesectoderm from the anterior and posterior poles of the embryo resulted in uniformly oriented divisions. Our data suggest that mesectoderm cells align their division angle to reduce strain caused by mechanical forces along the AP axis of the embryo. © 2017. Published by The Company of Biologists Ltd.

Method of reducing multipole content in a conductor assembly during manufacture

DOEpatents

Meinke, Rainer [Melbourne, FL

2011-08-09

A method for manufacture of a conductor assembly. The assembly is of the type which, when conducting current, generates a magnetic field or in which, in the presence of a changing magnetic field, a voltage is induced. In an example embodiment one or more first coil rows are formed. The assembly has multiple coil rows about an axis with outer coil rows formed about inner coil rows. A determination is made of deviations from specifications associated with the formed one or more first coil rows. One or more deviations correspond to a magnitude of a multipole field component which departs from a field specification. Based on the deviations, one or more wiring patterns are generated for one or more second coil rows to be formed about the one or more first coil rows. The one or more second coil rows are formed in the assembly. The magnitude of each multipole field component that departs from the field specification is offset.

Development of a benchmark factor to detect wrinkles in bending parts

NASA Astrophysics Data System (ADS)

Engel, Bernd; Zehner, Bernd-Uwe; Mathes, Christian; Kuhnhen, Christopher

2013-12-01

The rotary draw bending process finds special use in the bending of parts with small bending radii. Due to the support of the forming zone during the bending process, semi-finished products with small wall thicknesses can be bent. One typical quality characteristic is the emergence of corrugations and wrinkles at the inside arc. Presently, the standard for the evaluation of wrinkles is insufficient. The wrinkles' distribution along the longitudinal axis of the tube results in an average value [1]. An evaluation of the wrinkles is not carried out. Due to the lack of an adequate basis of assessment, coordination problems between customers and suppliers occur. They result from an imprecision caused by the lack of quantitative evaluability of the geometric deviations at the inside arc. The benchmark factor for the inside arc presented in this article is an approach to holistically evaluate the geometric deviations at the inside arc. The classification of geometric deviations is carried out according to the area of the geometric characteristics and the respective flank angles.

Method of reducing multipole content in a conductor assembly during manufacture

DOEpatents

Meinke, Rainer

2013-08-20

A method for manufacture of a conductor assembly. The assembly is of the type which, when conducting current, generates a magnetic field or in which, in the presence of a changing magnetic field, a voltage is induced. In an example embodiment one or more first coil rows are formed. The assembly has multiple coil rows about an axis with outer coil rows formed about inner coil rows. A determination is made of deviations from specifications associated with the formed one or more first coil rows. One or more deviations correspond to a magnitude of a multipole field component which departs from a field specification. Based on the deviations, one or more wiring patterns are generated for one or more second coil rows to be formed about the one or more first coil rows. The one or more second coil rows are formed in the assembly. The magnitude of each multipole field component that departs from the field specification is offset.

Thin Disk Accretion in the Magnetically-Arrested State

NASA Astrophysics Data System (ADS)

Avara, Mark J.; McKinney, Jonathan; Reynolds, Christopher S.

2016-01-01

Shakura-Sunyaev thin disk theory is fundamental to black hole astrophysics. Though applications of the theory are wide-spread and powerful tools for explaining observations, such as Soltan's argument using quasar power, broadened iron line measurements, continuum fitting, and recently reverberation mapping, a significant large-scale magnetic field causes substantial deviations from standard thin disk behavior. We have used fully 3D general relativistic MHD simulations with cooling to explore the thin (H/R~0.1) magnetically arrested disk (MAD) state and quantify these deviations. This work demonstrates that accumulation of large-scale magnetic flux into the MAD state is possible, and then extends prior numerical studies of thicker disks, allowing us to measure how jet power scales with the disk state, providing a natural explanation of phenomena like jet quenching in the high-soft state of X-ray binaries. We have also simulated thin MAD disks with a misaligned black hole spin axis in order to understand further deviations from thin disk theory that may significantly affect observations.

Image characterization metrics for muon tomography

NASA Astrophysics Data System (ADS)

Luo, Weidong; Lehovich, Andre; Anashkin, Edward; Bai, Chuanyong; Kindem, Joel; Sossong, Michael; Steiger, Matt

2014-05-01

Muon tomography uses naturally occurring cosmic rays to detect nuclear threats in containers. Currently there are no systematic image characterization metrics for muon tomography. We propose a set of image characterization methods to quantify the imaging performance of muon tomography. These methods include tests of spatial resolution, uniformity, contrast, signal to noise ratio (SNR) and vertical smearing. Simulated phantom data and analysis methods were developed to evaluate metric applicability. Spatial resolution was determined as the FWHM of the point spread functions in X, Y and Z axis for 2.5cm tungsten cubes. Uniformity was measured by drawing a volume of interest (VOI) within a large water phantom and defined as the standard deviation of voxel values divided by the mean voxel value. Contrast was defined as the peak signals of a set of tungsten cubes divided by the mean voxel value of the water background. SNR was defined as the peak signals of cubes divided by the standard deviation (noise) of the water background. Vertical smearing, i.e. vertical thickness blurring along the zenith axis for a set of 2 cm thick tungsten plates, was defined as the FWHM of vertical spread function for the plate. These image metrics provided a useful tool to quantify the basic imaging properties for muon tomography.

Analytical expressions for the log-amplitude correlation function of a plane wave through anisotropic atmospheric refractive turbulence.

PubMed

Gudimetla, V S Rao; Holmes, Richard B; Smith, Carey; Needham, Gregory

2012-05-01

The effect of anisotropic Kolmogorov turbulence on the log-amplitude correlation function for plane-wave fields is investigated using analysis, numerical integration, and simulation. A new analytical expression for the log-amplitude correlation function is derived for anisotropic Kolmogorov turbulence. The analytic results, based on the Rytov approximation, agree well with a more general wave-optics simulation based on the Fresnel approximation as well as with numerical evaluations, for low and moderate strengths of turbulence. The new expression reduces correctly to previously published analytic expressions for isotropic turbulence. The final results indicate that, as asymmetry becomes greater, the Rytov variance deviates from that given by the standard formula. This deviation becomes greater with stronger turbulence, up to moderate turbulence strengths. The anisotropic effects on the log-amplitude correlation function are dominant when the separation of the points is within the Fresnel length. In the direction of stronger turbulence, there is an enhanced dip in the correlation function at a separation close to the Fresnel length. The dip is diminished in the weak-turbulence axis, suggesting that energy redistribution via focusing and defocusing is dominated by the strong-turbulence axis. The new analytical expression is useful when anisotropy is observed in relevant experiments. © 2012 Optical Society of America

Precision tool holder with flexure-adjustable, three degrees of freedom for a four-axis lathe

DOEpatents

Bono, Matthew J [Pleasanton, CA; Hibbard, Robin L [Livermore, CA

2008-03-04

A precision tool holder for precisely positioning a single point cutting tool on 4-axis lathe, such that the center of the radius of the tool nose is aligned with the B-axis of the machine tool, so as to facilitate the machining of precision meso-scale components with complex three-dimensional shapes with sub-.mu.m accuracy on a four-axis lathe. The device is designed to fit on a commercial diamond turning machine and can adjust the cutting tool position in three orthogonal directions with sub-micrometer resolution. In particular, the tool holder adjusts the tool position using three flexure-based mechanisms, with two flexure mechanisms adjusting the lateral position of the tool to align the tool with the B-axis, and a third flexure mechanism adjusting the height of the tool. Preferably, the flexures are driven by manual micrometer adjusters. In this manner, this tool holder simplifies the process of setting a tool with sub-.mu.m accuracy, to substantially reduce the time required to set the tool.

Thermoluminescent dosimeters (TLD) quality assurance network in the Czech Republic.

PubMed

Kroutilķková, Daniela; Novotný, Josef; Judas, Libor

2003-02-01

The Czech thermoluminescent dosimeters (TLD) quality assurance network was established in 1997. Its aim is to pursue a regular independent quality audit in Czech radiotherapy centres and to support state supervision. The audit is realised via mailed TL dosimetry. The TLD system consists of encapsulated LiF:Mg,Ti powder (type MT-N) read with Harshaw manual reader model 4000. Basic mode of the TLD audit covers measurements under reference conditions, specifically beam calibration checks for all clinically used photon and electron beams. Advanced mode consists of measurements under both reference and non-reference conditions using a solid multipurpose phantom ('Leuven phantom') for photon beams. The radiotherapy centres are instructed to deliver to the TLD on central beam axis absorbed dose of 2 Gy calculated with their treatment planning system for a particular treatment set-up. The TLD measured doses are compared with the calculated ones. Deviations of +/-3% are considered acceptable for both basic and advanced mode of the audit. There are 34 radiotherapy centres in the Czech Republic. They undergo the basic mode of the TLD audit regularly every 2 years. If a centre shows a deviation outside the acceptance level, it is audited more often. Presently, most of the checked beams comply with the acceptance level. The advanced TLD audit has been implemented as a pilot study for the present. The results were mostly within the acceptance limit for the measurements on-axis, whereas for off-axis points they fell beyond the limit more frequently, especially for set-ups with inhomogeneities, oblique incidence and wedges. The results prove the importance of the national TLD quality assurance network. It has contributed to the improvement of clinical dosimetry in the Czech Republic. In addition, it helps the regulatory authority to monitor effectively and regularly radiotherapy centres.

Comparison of changes in the transverse dental axis between patients with skeletal Class III malocclusion and facial asymmetry treated by orthognathic surgery with and without presurgical orthodontic treatment.

PubMed

Song, Han-Sol; Choi, Sung-Hwan; Cha, Jung-Yul; Lee, Kee-Joon; Yu, Hyung-Seog

2017-07-01

To evaluate transverse skeletal and dental changes, including those in the buccolingual dental axis, between patients with skeletal Class III malocclusion and facial asymmetry after bilateral intraoral vertical ramus osteotomy with and without presurgical orthodontic treatment. This retrospective study included 29 patients with skeletal Class III malocclusion and facial asymmetry including menton deviation > 4 mm from the midsagittal plane. To evaluate changes in transverse skeletal and dental variables (i.e., buccolingual inclination of the upper and lower canines and first molars), the data for 16 patients who underwent conventional orthognathic surgery (CS) were compared with those for 13 patients who underwent preorthodontic orthognathic surgery (POGS), using three-dimensional computed tomography at initial examination, 1 month before surgery, and at 7 days and 1 year after surgery. The 1-year postsurgical examination revealed no significant changes in the postoperative transverse dental axis in the CS group. In the POGS group, the upper first molar inclined lingually on both sides (deviated side, -1.8° ± 2.8°, p = 0.044; nondeviated side, -3.7° ± 3.3°, p = 0.001) and the lower canine inclined lingually on the nondeviated side (4.0° ± 5.4°, p = 0.022) during postsurgical orthodontic treatment. There were no significant differences in the skeletal and dental variables between the two groups at 1 year after surgery. POGS may be a clinically acceptable alternative to CS as a treatment to achieve stable transverse axes of the dentition in both arches in patients with skeletal Class III malocclusion and facial asymmetry.

Piezoelectrically pushed rotational micromirrors using detached PZT actuators for wide-angle optical switch applications

NASA Astrophysics Data System (ADS)

Kim, Sung-Jin; Cho, Young-Ho; Nam, Hyo-Jin; Bu, Jong Uk

2008-12-01

This paper presents a torsional micromirror detached from PZT actuators (TMD), whose rotational motion is achieved by push bars in the PZT actuators, detached from the micromirror. The push bar mechanism is intended to reduce the bending, tensile and torsional constraints generated by the conventional bending bar mechanism, where the torsional micromirror is attached to the PZT actuators (TMA). We have designed, fabricated and tested the prototypes of TMDs for single-axis and dual-axis rotations, respectively. The single-axis TMD generates a static rotational angle of 6.1° at 16 Vdc, which is six times larger than that of the single-axis TMA, 0.9°. However, the rotational response curve of TMD shows hysteresis and zero offset due to the static friction from the initial contact force between the cover and the push bar in the PZT actuator. We have shown that 63.2% of the hysteresis is reduced by eliminating the initial contact force of the PZT actuator. The dual-axis TMD generates static rotational angles of 5.5° and 4.7° in the x-axis and y-axis, respectively, at 16 Vdc. The measured resonant frequencies of the dual-axis TMD are 2.1 ± 0.1 kHz in the x-axis and 1.7 ± 0.1 kHz in the y-axis. The dual-axis TMD shows stable operation without severe wear for 21.6 million cycles driven by the 16 Vp-p sinusoidal wave signal at room temperature.

Reactor Pressure Vessel Fracture Analysis Capabilities in Grizzly

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

Spencer, Benjamin; Backman, Marie; Chakraborty, Pritam

2015-03-01

Efforts have been underway to develop fracture mechanics capabilities in the Grizzly code to enable it to be used to perform deterministic fracture assessments of degraded reactor pressure vessels (RPVs). Development in prior years has resulted a capability to calculate -integrals. For this application, these are used to calculate stress intensity factors for cracks to be used in deterministic linear elastic fracture mechanics (LEFM) assessments of fracture in degraded RPVs. The -integral can only be used to evaluate stress intensity factors for axis-aligned flaws because it can only be used to obtain the stress intensity factor for pure Mode Imore » loading. Off-axis flaws will be subjected to mixed-mode loading. For this reason, work has continued to expand the set of fracture mechanics capabilities to permit it to evaluate off-axis flaws. This report documents the following work to enhance Grizzly’s engineering fracture mechanics capabilities for RPVs: • Interaction Integral and -stress: To obtain mixed-mode stress intensity factors, a capability to evaluate interaction integrals for 2D or 3D flaws has been developed. A -stress evaluation capability has been developed to evaluate the constraint at crack tips in 2D or 3D. Initial verification testing of these capabilities is documented here. • Benchmarking for axis-aligned flaws: Grizzly’s capabilities to evaluate stress intensity factors for axis-aligned flaws have been benchmarked against calculations for the same conditions in FAVOR. • Off-axis flaw demonstration: The newly-developed interaction integral capabilities are demon- strated in an application to calculate the mixed-mode stress intensity factors for off-axis flaws. • Other code enhancements: Other enhancements to the thermomechanics capabilities that relate to the solution of the engineering RPV fracture problem are documented here.« less

[How safe are orthoroentgenograms in determining the amount of correction for varus deformities?].

PubMed

Gürsu, Sarper; Yıldırım, Timur; Issın, Ahmet; Sofu, Hakan; Sahin, Vedat

2014-01-01

In this study, we evaluated the effects of the distance of the legs from the midline on alignment and angles of the lower extremities in orthoroentgenograms. Between March 2012 and April 2013, 95 limbs of 56 patients with varus deformity who underwent orthoroentgenogram to identify the amount of joint laxity in two positions were included in this study. The initial X-ray was performed with the feet in contact, while the other was performed as the legs were abducted to be in line with the shoulders. For each orthoroentgenogram, the mean mechanical axis angle, anatomical axis, and joint line orientation angles were measured retrospectively. These measurements were repeated for 43 limbs with varus deformity >10°. In the orthoroentgenograms with the feet in contact, the mean mechanical axis angle was 9.58°±5.7°, (0.20°; 26.0°), the mean anatomical axis angle 3.65°±6.14°, (-9.0°; 21.0°), and the mean joint line orientation angle -3.41°±2.52°, (-12.0°; 1.60°). In the orthoroentgenograms with the legs abducted, the mean mechanical axis angle was 7.73°±5.58°, (-3.0°; 23.0°), the mean anatomical axis angle 2.62°±5.87°, (-11.0°; 18.30°), and mean joint line orientation angle was -2.44°±2.41°, (-13.0°; 3.0°). The differences in the angles between the two positions were statistically significant (p<0.005). Our study results showed that the mean values of mechanical axis angle, anatomical axis and the joint line orientation angle were higher in orthoroentgenograms with the feet in contact than the orthoroentgenograms with the legs abducted in patients with varus gonarthrosis. We suggest that this may lead to mistakes in the preoperative planning. Ideal positions should be standardized to minimize possible problems.

The Hypothalamic-Pituitary-Adrenal Axis and Anesthetics: A Review.

PubMed

Besnier, Emmanuel; Clavier, Thomas; Compere, Vincent

2017-04-01

The hypothalamic-pituitary-adrenal (HPA) axis is essential for human adaptation to stress. However, many anesthetic agents may interfere with the activity of this axis. Although etomidate is known for its suppressive effect on HPA axis function, in vitro evidence suggests that many other drugs used in anesthesia care may also interfere with HPA activity. In this review, we discuss the mechanisms by which all HPA axis activity may be altered during anesthesia and critical care and focus on the impact of hypnotic and analgesic drugs.

A new method to evaluate the quality of single crystal Cu by an X-ray diffraction butterfly pattern method

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

Xu Zhenming; Guo Zhenqi; Li Jianguo

2004-12-15

A new method for the evaluation of the quality of an Ohno continuous cast (OCC) Cu single crystal by X-ray diffraction (XRD) butterfly pattern was brought forward. Experimental results show that the growth direction of single crystal Cu is inclined from both sides of the single crystal Cu rod to the axis and is axially symmetric. The degree of deviation from the [100] orientation from the crystal axis is less than 5 deg. with a casting speed 10-40 mm/min. The orientation of single crystal Cu does not have a fixed direction but is in a regular range. Moreover, the orientationmore » of stray grains in the single crystal Cu is random from continuous casting.« less

Guided waves and defect scattering in metal matrix composite plates

NASA Technical Reports Server (NTRS)

Datta, Subhendu K.; Bratton, Robert L.; Shah, Arvind H.

1989-01-01

Guided Rayleigh-Lamb waves in a continuous graphite fiber reinforced magnesium plate has been studied. The interest in this material arises from its high thermal stability and because it provides high strength-to-weight ratio. Previous studies have shown that for wavelengths much larger than the fiber diameters and spacing, the material can be characterized as transversely isotropic with the symmetry axis aligned with the fiber direction. Because of the high longitudinal stiffness of the graphite fibers, the material shows strong anisotropy, with very high modulus in the fiber direction. For this reason, dispersion of guided waves is strongly influenced by the deviation of the direction of propagation from the symmetry axis. Results are given for propagation in different directions and for scattering of antiplane shear waves by surface-breaking cracks and delaminations.

The use of two-axis high precision inclination sensors in determining headframe deflection

NASA Astrophysics Data System (ADS)

Jaśkowski, Wojciech; Jabłoński, Mateusz; Ulmaniec, Małgorzata; Paraszczuk, Krzysztof

2018-04-01

Reliability of transport equipment in the shaft depends, among other things, on the accuracy of the vertical foundation of the headframe together with elements of the hoisting equipment over the shaft. Any deviations beyond the installation and movement tolerances may cause incorrect or even dangerous operation of the hoisting equipment in the shaft. Therefore the headframe is subjected to periodic inventory measurements, which prevent the movement in the shaft and the smooth operation of the whole underground mine. The Wieliczka Salt Mine developed a project for the installation of precision Nivel 220 two-axis inclinometers on Kinga and Daniłowicz headframes. The paper summarizes the initial conclusions resulting from the first year of the system operation and indicates the directions of its development.

Overhead Crane Computer Model

NASA Astrophysics Data System (ADS)

Enin, S. S.; Omelchenko, E. Y.; Fomin, N. V.; Beliy, A. V.

2018-03-01

The paper has a description of a computer model of an overhead crane system. The designed overhead crane system consists of hoisting, trolley and crane mechanisms as well as a payload two-axis system. With the help of the differential equation of specified mechanisms movement derived through Lagrange equation of the II kind, it is possible to build an overhead crane computer model. The computer model was obtained using Matlab software. Transients of coordinate, linear speed and motor torque of trolley and crane mechanism systems were simulated. In addition, transients of payload swaying were obtained with respect to the vertical axis. A trajectory of the trolley mechanism with simultaneous operation with the crane mechanism is represented in the paper as well as a two-axis trajectory of payload. The designed computer model of an overhead crane is a great means for studying positioning control and anti-sway control systems.

A Miniature Magnetic-Force-Based Three-Axis AC Magnetic Sensor with Piezoelectric/Vibrational Energy-Harvesting Functions

PubMed Central

Hung, Chiao-Fang; Yeh, Po-Chen; Chung, Tien-Kan

2017-01-01

In this paper, we demonstrate a miniature magnetic-force-based, three-axis, AC magnetic sensor with piezoelectric/vibrational energy-harvesting functions. For magnetic sensing, the sensor employs a magnetic–mechanical–piezoelectric configuration (which uses magnetic force and torque, a compact, single, mechanical mechanism, and the piezoelectric effect) to convert x-axis and y-axis in-plane and z-axis magnetic fields into piezoelectric voltage outputs. Under the x-axis magnetic field (sine-wave, 100 Hz, 0.2–3.2 gauss) and the z-axis magnetic field (sine-wave, 142 Hz, 0.2–3.2 gauss), the voltage output with the sensitivity of the sensor are 1.13–26.15 mV with 8.79 mV/gauss and 1.31–8.92 mV with 2.63 mV/gauss, respectively. In addition, through this configuration, the sensor can harness ambient vibrational energy, i.e., possessing piezoelectric/vibrational energy-harvesting functions. Under x-axis vibration (sine-wave, 100 Hz, 3.5 g) and z-axis vibration (sine-wave, 142 Hz, 3.8 g), the root-mean-square voltage output with power output of the sensor is 439 mV with 0.333 μW and 138 mV with 0.051 μW, respectively. These results show that the sensor, using this configuration, successfully achieves three-axis magnetic field sensing and three-axis vibration energy-harvesting. Due to these features, the three-axis AC magnetic sensor could be an important design reference in order to develop future three-axis AC magnetic sensors, which possess energy-harvesting functions, for practical industrial applications, such as intelligent vehicle/traffic monitoring, processes monitoring, security systems, and so on. PMID:28208693

Calibration of z-axis linearity for arbitrary optical topography measuring instruments

NASA Astrophysics Data System (ADS)

Eifler, Matthias; Seewig, Jörg; Hering, Julian; von Freymann, Georg

2015-05-01

The calibration of the height axis of optical topography measurement instruments is essential for reliable topography measurements. A state of the art technology for the calibration of the linearity and amplification of the z-axis is the use of step height artefacts. However, a proper calibration requires numerous step heights at different positions within the measurement range. The procedure is extensive and uses artificial surface structures that are not related to real measurement tasks. Concerning these limitations, approaches should to be developed that work for arbitrary topography measurement devices and require little effort. Hence, we propose calibration artefacts which are based on the 3D-Abbott-Curve and image desired surface characteristics. Further, real geometric structures are used as an initial point of the calibration artefact. Based on these considerations, an algorithm is introduced which transforms an arbitrary measured surface into a measurement artefact for the z-axis linearity. The method works both for profiles and topographies. For considering effects of manufacturing, measuring, and evaluation an iterative approach is chosen. The mathematical impact of these processes can be calculated with morphological signal processing. The artefact is manufactured with 3D laser lithography and characterized with different optical measurement devices. An introduced calibration routine can calibrate the entire z-axis-range within one measurement and minimizes the required effort. With the results it is possible to locate potential linearity deviations and to adjust the z-axis. Results of different optical measurement principles are compared in order to evaluate the capabilities of the new artefact.

Evaluating the Impact of the Number of Satellite Altimeters Used in an Assimilative Ocean Prediction System

DTIC Science & Technology

2009-10-20

standard deviation. The y axis indicates the scaled MB, MB95 MB 1 N N j51 (O j O)2 2 4 3 5 1/2 , (12) or the biweight version, MBbw9 5 MBbw hhO j iibw...RMSEbw9unbiased 5 RMSEbwunbiased hhO j iibw . (15) To investigate the impact of outliers, results from both the Gaussian statistics [Eqs. (12) and

4-Meth-oxy-N-(1-methyl-1H-indazol-5-yl)benzene-sulfonamide.

PubMed

Chicha, Hakima; Rakib, El Mostapha; Geffken, Detlef; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

The indazole ring system [maximum deviation = 0.013 (2) Å] of the title compound, C15H15N3O3S, makes a dihedral angle of 50.11 (7)° with the benzene ring. In the crystal, cohesion is provided by C-H⋯O and N-H⋯N hydrogen bonds, which link the molecules into chains propagating along the b-axis direction.

Five-DOF innovative linear MagLev slider to account for pitch, tilt and load uncertainty

NASA Astrophysics Data System (ADS)

Kao, Yi-Ming; Tsai, Nan-Chyuan; Chiu, Hsin-Lin

2017-02-01

This paper is focused at position deviation regulation upon a slider by Fuzzy Sliding Mode Control (FSMC). Five Degrees Of Freedom (DOF) of position deviation are required to be regulated except for the direction (i.e., X-axis) in which the slider moves forward and backward. Totally 8 sets of Magnetic Actuators (MAs) and an Electro-Pneumatic Transducer (EPT) are employed to drive the slider carrying loads under the commands of FSMC. EPT is applied to adjust the pressure of compressed air to counterbalance the weight of slider itself. At first, the system dynamic model of slider, including load uncertainty and load position uncertainty, is established. Intensive computer simulations are undertaken to verify the validity of proposed control strategy. Finally, a prototype of realistic slider position deviation regulation system is successfully built up. According to the experiments by cooperation of pneumatic and magnetic control, the actual linear position deviations of slider can be regulated within ±8 μm and angular position deviations within ±1 mini-degrees. From the viewpoint of energy consumption, the applied currents to 8 sets of MAs are all below 1.2 A. To sum up, the closed-loop levitation system by cooperation of pneumatic and magnetic control is capable to account for load uncertainty and uncertainty of the standing position of load to be carried.

Evaluation of three different validation procedures regarding the accuracy of template-guided implant placement: an in vitro study.

PubMed

Vasak, Christoph; Strbac, Georg D; Huber, Christian D; Lettner, Stefan; Gahleitner, André; Zechner, Werner

2015-02-01

The study aims to evaluate the accuracy of the NobelGuide™ (Medicim/Nobel Biocare, Göteborg, Sweden) concept maximally reducing the influence of clinical and surgical parameters. Moreover, the study was to compare and validate two validation procedures versus a reference method. Overall, 60 implants were placed in 10 artificial edentulous mandibles according to the NobelGuide™ protocol. For merging the pre- and postoperative DICOM data sets, three different fusion methods (Triple Scan Technique, NobelGuide™ Validation software, and AMIRA® software [VSG - Visualization Sciences Group, Burlington, MA, USA] as reference) were applied. Discrepancies between the virtual and the actual implant positions were measured. The mean deviations measured with AMIRA® were 0.49 mm (implant shoulder), 0.69 mm (implant apex), and 1.98°mm (implant axis). The Triple Scan Technique as well as the NobelGuide™ Validation software revealed similar deviations compared with the reference method. A significant correlation between angular and apical deviations was seen (r = 0.53; p < .001). A greater implant diameter was associated with greater deviations (p = .03). The Triple Scan Technique as a system-independent validation procedure as well as the NobelGuide™ Validation software are in accordance with the AMIRA® software. The NobelGuide™ system showed similar or less spatial and angular deviations compared with others. © 2013 Wiley Periodicals, Inc.

Summary: High Temperature Downhole Motor

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

Raymond, David W.

2017-10-01

Directional drilling can be used to enable multi-lateral completions from a single well pad to improve well productivity and decrease environmental impact. Downhole rotation is typically developed with a motor in the Bottom Hole Assembly (BHA) that develops drilling power (speed and torque) necessary to drive rock reduction mechanisms (i.e., the bit) apart from the rotation developed by the surface rig. Historically, wellbore deviation has been introduced by a “bent-sub,” located in the BHA, that introduces a small angular deviation, typically less than 3 degrees, to allow the bit to drill off-axis with orientation of the BHA controlled at themore » surface. The development of a high temperature downhole motor would allow reliable use of bent subs for geothermal directional drilling. Sandia National Laboratories is pursuing the development of a high temperature motor that will operate on either drilling fluid (water-based mud) or compressed air to enable drilling high temperature, high strength, fractured rock. The project consists of designing a power section based upon geothermal drilling requirements; modeling and analysis of potential solutions; and design, development and testing of prototype hardware to validate the concept. Drilling costs contribute substantially to geothermal electricity production costs. The present development will result in more reliable access to deep, hot geothermal resources and allow preferential wellbore trajectories to be achieved. This will enable development of geothermal wells with multi-lateral completions resulting in improved geothermal resource recovery, decreased environmental impact and enhanced well construction economics.« less

Wrinkling Phenomena to Explain Vertical Fold Defects in DC-Cast Al-Mg4.5

NASA Astrophysics Data System (ADS)

Davis, J. Lee; Mendez, Patricio F.

Some aluminum ingots cast by the direct chill method are subject to surface defects on the molten ingot head during casting while others are not. These defects -commonly called "vertical folds" -are frozen into the casting and must be removed prior to rolling. Vertical folds are found on top of the molten ingot surface where areas of thin oxide are (a) bounded by physical constraints and (b) stretched. Physical constraints include (1) substantially thicker oxide or (2) a refractory skim ring adjacent to the thin oxide. The mechanism of wrinkling is suggested for the formation of vertical folds. Wrinkling behavior is described by physical expressions for an elastic sheet in tension whose behavior depends upon thickness h, length L, Young's modulus E, and Poisson's ratio v. The depth and frequency of folds in the thin, elastic sheet parallel to the tensile axis between the two "constraints" can be calculated from these parameters. The observed frequency (and amplitude) of vertical folds in DC-cast aluminum has been found to obey similar wrinkling laws. The frequency-dependence (λ) is examined and found to be related to classic wrinkling parameters but with significant scaling deviations. These deviations may be related to the pseudo-plasticity (self-healing behavior) of the oxide film on the molten surface. A wrinkling model coupled with pseudo-plasticity predicts subtle behaviors in DC casting of Al-Mg4.5 that are not explained by other theories.

Space imaging measurement system based on fixed lens and moving detector

NASA Astrophysics Data System (ADS)

Akiyama, Akira; Doshida, Minoru; Mutoh, Eiichiro; Kumagai, Hideo; Yamada, Hirofumi; Ishii, Hiromitsu

2006-08-01

We have developed the Space Imaging Measurement System based on the fixed lens and fast moving detector to the control of the autonomous ground vehicle. The space measurement is the most important task in the development of the autonomous ground vehicle. In this study we move the detector back and forth along the optical axis at the fast rate to measure the three-dimensional image data. This system is just appropriate to the autonomous ground vehicle because this system does not send out any optical energy to measure the distance and keep the safety. And we use the digital camera of the visible ray range. Therefore it gives us the cost reduction of the three-dimensional image data acquisition with respect to the imaging laser system. We can combine many pieces of the narrow space imaging measurement data to construct the wide range three-dimensional data. This gives us the improvement of the image recognition with respect to the object space. To develop the fast movement of the detector, we build the counter mass balance in the mechanical crank system of the Space Imaging Measurement System. And then we set up the duct to prevent the optical noise due to the ray not coming through lens. The object distance is derived from the focus distance which related to the best focused image data. The best focused image data is selected from the image of the maximum standard deviation in the standard deviations of series images.

Mechanical behavior and fracture characteristics of off-axis fiber composites. 2: Theory and comparisons

NASA Technical Reports Server (NTRS)

Chamis, C. C.; Sinclair, J. H.

1978-01-01

The mechanical behavior and stresses inducing fracture modes of unidirectional high-modulus graphite-fiber/epoxy composites subjected to off-axis tensile loads were investigated theoretically. The investigation included the use of composite mechanics, combined-stress failure criteria, and finite-element stress analysis. The results are compared with experimental data and led to the formulation of criteria and convenient plotting procedures for identifying, characterizing, and quantifying these fracture modes.

Determination of the topological shape of integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria in the detergent solution by small-angle X-ray scattering.

PubMed

Hong, Xinguo; Weng, Yu-Xiang; Li, Ming

2004-02-01

The topological shape of the integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria Rhodobacter spheroides 2.4.1 in detergent solution has been determined from synchrotron small-angle X-ray scattering data using direct curve-fitting by the ellipsoid, ab initio shape determination methods of simulated annealing algorithm and multipole expansion, respectively. The results indicate that the LH2 protein in aqueous solution is encapsulated by a monolayered detergent shell. The detergent-stabilized structure has the shape of an oblate plate, with a thickness of 40 A, a long axis of 110 A, and a short axis of 85 A. After correction for the detergent shell, the shape of the LH2 core is also an oblate plate with a height of 40 A, a long axis of 80 A, and a short axis of 55 A. In contrast to the cylindrical crystal structure with a height of 40 A and a diameter of 68 A, the molecular shape of the LH2 complex in detergent solution clearly deviates from the ringlike crystal structure, with an eccentricity found to be 0.59-consistent with the result of single molecular spectroscopy study of the isolated single LH2 molecules.

Determination of the Topological Shape of Integral Membrane Protein Light-Harvesting Complex LH2 from Photosynthetic Bacteria in the Detergent Solution by Small-Angle X-Ray Scattering

PubMed Central

Hong, Xinguo; Weng, Yu-Xiang; Li, Ming

2004-01-01

The topological shape of the integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria Rhodobacter spheroides 2.4.1 in detergent solution has been determined from synchrotron small-angle X-ray scattering data using direct curve-fitting by the ellipsoid, ab initio shape determination methods of simulated annealing algorithm and multipole expansion, respectively. The results indicate that the LH2 protein in aqueous solution is encapsulated by a monolayered detergent shell. The detergent-stabilized structure has the shape of an oblate plate, with a thickness of 40 Å, a long axis of 110 Å, and a short axis of 85 Å . After correction for the detergent shell, the shape of the LH2 core is also an oblate plate with a height of 40 Å, a long axis of 80 Å, and a short axis of 55 Å. In contrast to the cylindrical crystal structure with a height of 40 Å and a diameter of 68 Å, the molecular shape of the LH2 complex in detergent solution clearly deviates from the ringlike crystal structure, with an eccentricity found to be 0.59—consistent with the result of single molecular spectroscopy study of the isolated single LH2 molecules. PMID:14747343

Rotational properties of planetary satellites

NASA Technical Reports Server (NTRS)

Peale, S. J.

1991-01-01

Properties of satellite rotation that are observable in principle, include the rotation period, the orientation of the spin axis relative to the orbit plane, precession of the spin axis due to gravitational torques, nonprincipal axis rotation or wobble, and deviations from uniform principle axis rotation or libration. Considerable order is observed in current satellite rotation states, and it is of interest to ascertain how this order came about and why some satellites do not conform to the dominant norm. There is a strong coupling between the spin and orbital motions that is primarily responsible for maintaining the ordered rotation states in most cases, but this coupling is equally responsible for destroying any chance of orderly rotation for Saturn's satellite Hyperion. Understanding the processes which constrain current rotation states as well as those of an evolutionary nature which could have brought the individual satellites to their observed rotation and orbit states allows us to sometimes infer interior properties of some satellite or even of its primary planet, although, attempts to deduce primordial rotation states are usually frustrated. The observed rotational properties of the planetary satellites are summarized, and the understanding of the processes maintaining and those leading to the observed states are outlined. Some of the inferences that can be drawn about intrinsic properties of the bodies themselves are indicated.

Error-compensation model for simultaneous measurement of five degrees of freedom motion errors of a rotary axis

NASA Astrophysics Data System (ADS)

Bao, Chuanchen; Li, Jiakun; Feng, Qibo; Zhang, Bin

2018-07-01

This paper introduces an error-compensation model for our measurement method to measure five motion errors of a rotary axis based on fibre laser collimation. The error-compensation model is established in a matrix form using the homogeneous coordinate transformation theory. The influences of the installation errors, error crosstalk, and manufacturing errors are analysed. The model is verified by both ZEMAX simulation and measurement experiments. The repeatability values of the radial and axial motion errors are significantly suppressed by more than 50% after compensation. The repeatability experiments of five degrees of freedom motion errors and the comparison experiments of two degrees of freedom motion errors of an indexing table were performed by our measuring device and a standard instrument. The results show that the repeatability values of the angular positioning error ε z and tilt motion error around the Y axis ε y are 1.2″ and 4.4″, and the comparison deviations of the two motion errors are 4.0″ and 4.4″, respectively. The repeatability values of the radial and axial motion errors, δ y and δ z , are 1.3 and 0.6 µm, respectively. The repeatability value of the tilt motion error around the X axis ε x is 3.8″.

Accuracy in identifying the elbow rotation axis on simulated fluoroscopic images using a new anatomical landmark.

PubMed

Wiggers, J K; Snijders, R M; Dobbe, J G G; Streekstra, G J; den Hartog, D; Schep, N W L

2017-11-01

External fixation of the elbow requires identification of the elbow rotation axis, but the accuracy of traditional landmarks (capitellum and trochlea) on fluoroscopy is limited. The relative distance (RD) of the humerus may be helpful as additional landmark. The first aim of this study was to determine the optimal RD that corresponds to an on-axis lateral image of the elbow. The second aim was to assess whether the use of the optimal RD improves the surgical accuracy to identify the elbow rotation axis on fluoroscopy. CT scans of elbows from five volunteers were used to simulate fluoroscopy; the actual rotation axis was calculated with CT-based flexion-extension analysis. First, three observers measured the optimal RD on simulated fluoroscopy. The RD is defined as the distance between the dorsal part of the humerus and the projection of the posteromedial cortex of the distal humerus, divided by the anteroposterior diameter of the humerus. Second, eight trauma surgeons assessed the elbow rotation axis on simulated fluoroscopy. In a preteaching session, surgeons used traditional landmarks. The surgeons were then instructed how to use the optimal RD as additional landmark in a postteaching session. The deviation from the actual rotation axis was expressed as rotational and translational error (±SD). Measurement of the RD was robust and easily reproducible; the optimal RD was 45%. The surgeons identified the elbow rotation axis with a mean rotational error decreasing from 7.6° ± 3.4° to 6.7° ± 3.3° after teaching how to use the RD. The mean translational error decreased from 4.2 ± 2.0 to 3.7 ± 2.0 mm after teaching. The humeral RD as additional landmark yielded small but relevant improvements. Although fluoroscopy-based external fixator alignment to the elbow remains prone to error, it is recommended to use the RD as additional landmark.

Cardiovascular anatomy in children with bidirectional Glenn anastomosis, regarding the transcatheter Fontan completion.

PubMed

Sizarov, Aleksander; Raimondi, Francesca; Bonnet, Damien; Boudjemline, Younes

2018-04-01

Transcatheter stent-secured completion of total cavopulmonary connection (TCPC) after surgical preparations during the Glenn anastomosis procedure has been reported, but complications from this approach have precluded its clinical acceptance. To analyse cardiovascular morphology and dimensions in children with bidirectional Glenn anastomosis, regarding the optimal device design for transcatheter Fontan completion without special surgical "preconditionings". We retrospectively analysed 60 thoracic computed tomography and magnetic resonance angiograms performed in patients with a median age of 4.1 years (range: 1.8-17.1 years). Additionally, we simulated TCPC completion using different intra-atrial stent-grafts in a three-dimensional model of the representative anatomy, and performed calculations to determine the optimal stent-graft dimensions, using measured distances. Two types of cardiovascular arrangement were identified: left atrium interposing between the right pulmonary artery (RPA) and inferior vena cava, with the right upper pulmonary vein (RUPV) orifice close to the intercaval axis (65%); and intercaval axis traversing only the right(-sided) atrial cavity, with the RUPV located posterior to the atrial wall (35%). In the total population, the shortest median RPA-to-atrial wall distance was 1.9mm (range: 0.6-13.8mm), while the mean intra-atrial distance along the intercaval axis was 50.1±11.2mm. Regardless of the arrangement, 83% of all patients required a deviation of at least 5.9±2.4mm (range: 1.2-12.7mm) of the stent-graft centre at the RUPV level anteriorly to the intercaval axis to avoid covering or compressing this vein. Fixing the anterior deviation of the curved stent-graft centre at 10mm significantly decreased the range of bend angle per every given RUPV-RPA distance. For both types of cardiovascular arrangement, after conventional bidirectional Glenn anastomosis, the intra-atrial curved stent-graft seemed most suitable for achieving uncomplicated TCPC completion percutaneously without previous surgical "preconditionings" in the majority of children. Experimental study is necessary to validate this conclusion. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Flexner 2.0-Longitudinal Study of Student Participation in a Campus-Wide General Pathology Course for Graduate Students at The University of Arizona.

PubMed

Briehl, Margaret M; Nelson, Mark A; Krupinski, Elizabeth A; Erps, Kristine A; Holcomb, Michael J; Weinstein, John B; Weinstein, Ronald S

2016-01-01

Faculty members from the Department of Pathology at The University of Arizona College of Medicine-Tucson have offered a 4-credit course on enhanced general pathology for graduate students since 1996. The course is titled, "Mechanisms of Human Disease." Between 1997 and 2016, 270 graduate students completed Mechanisms of Human Disease. The students came from 21 programs of study. Analysis of Variance, using course grade as the dependent and degree, program, gender, and year (1997-2016) as independent variables, indicated that there was no significant difference in final grade (F = 0.112; P = .8856) as a function of degree (doctorate: mean = 89.60, standard deviation = 5.75; master's: mean = 89.34, standard deviation = 6.00; certificate program: mean = 88.64, standard deviation = 8.25), specific type of degree program (F = 2.066, P = .1316; life sciences: mean = 89.95, standard deviation = 6.40; pharmaceutical sciences: mean = 90.71, standard deviation = 4.57; physical sciences: mean = 87.79, standard deviation = 5.17), or as a function of gender (F = 2.96, P = .0865; males: mean = 88.09, standard deviation = 8.36; females: mean = 89.58, standard deviation = 5.82). Students in the physical and life sciences performed equally well. Mechanisms of Human Disease is a popular course that provides students enrolled in a variety of graduate programs with a medical school-based course on mechanisms of diseases. The addition of 2 new medically oriented Master of Science degree programs has nearly tripled enrollment. This graduate level course also potentially expands the interdisciplinary diversity of participants in our interprofessional education and collaborative practice exercises.

Flexner 2.0—Longitudinal Study of Student Participation in a Campus-Wide General Pathology Course for Graduate Students at The University of Arizona

PubMed Central

Briehl, Margaret M.; Nelson, Mark A.; Krupinski, Elizabeth A.; Erps, Kristine A.; Holcomb, Michael J.; Weinstein, John B.

2016-01-01

Faculty members from the Department of Pathology at The University of Arizona College of Medicine-Tucson have offered a 4-credit course on enhanced general pathology for graduate students since 1996. The course is titled, “Mechanisms of Human Disease.” Between 1997 and 2016, 270 graduate students completed Mechanisms of Human Disease. The students came from 21 programs of study. Analysis of Variance, using course grade as the dependent and degree, program, gender, and year (1997-2016) as independent variables, indicated that there was no significant difference in final grade (F = 0.112; P = .8856) as a function of degree (doctorate: mean = 89.60, standard deviation = 5.75; master’s: mean = 89.34, standard deviation = 6.00; certificate program: mean = 88.64, standard deviation = 8.25), specific type of degree program (F = 2.066, P = .1316; life sciences: mean = 89.95, standard deviation = 6.40; pharmaceutical sciences: mean = 90.71, standard deviation = 4.57; physical sciences: mean = 87.79, standard deviation = 5.17), or as a function of gender (F = 2.96, P = .0865; males: mean = 88.09, standard deviation = 8.36; females: mean = 89.58, standard deviation = 5.82). Students in the physical and life sciences performed equally well. Mechanisms of Human Disease is a popular course that provides students enrolled in a variety of graduate programs with a medical school-based course on mechanisms of diseases. The addition of 2 new medically oriented Master of Science degree programs has nearly tripled enrollment. This graduate level course also potentially expands the interdisciplinary diversity of participants in our interprofessional education and collaborative practice exercises. PMID:28725783

Field experiment of 800× off-axis XR-Köhler concentrator module on a carousel tracker

NASA Astrophysics Data System (ADS)

Yamada, Noboru; Okamoto, Kazuya; Ijiro, Toshikazu; Suzuki, Takao; Maemura, Toshihiko; Kawaguchi, Takashi; Takahashi, Hiroshi; Sato, Takashi; Hernandez, Maikel; Benitez, Pablo; Chaves, Julio; Cvetkovic, Aleksandra; Vilaplana, Juan; Mohedano, Ruben; Mendes-Lopes, Joao; Miñano, Juan Carlos

2013-09-01

This paper presents the design and preliminary experimental results of a concentrator-type photovoltaic module based on a free-form off-axis 800×XR-Köhler concentrator. The off-axis XR-Köhler concentrator is one of the advanced concentrators that perform high concentration with a large acceptance angle and excellent irradiance uniformity on a solar cell. As a result of on-sun characterization of the unglazed single-cell unit test rig, the temperature-corrected DC module efficiency was 32.2% at 25 °C without an anti-reflective (AR) coating on the secondary optics, and the acceptance angle was more than ±1.0°. In addition, the non-corrected DC efficiency of an individual cell in a glazed 8-cell unit module mounted on a carousel tracking system was measured. The individual efficiency deviated in the range of 24.3-27.4%, owing to the mirror shape and alignment errors. The resultant series-connected efficiency was approximately 25% at direct normal irradiation (DNI) of 770 W/m2.

Characterization of the non axial thrust generated by large solid propellant rocket motors in three axis stabilized ascent

NASA Technical Reports Server (NTRS)

Kosmann, W. J.; Dionne, E. R.; Klemetson, R. W.

1978-01-01

Nonaxial thrusts produced by solid rocket motors during three-axis stabilized attitude control have been determined from ascent experience on twenty three Burner II, Burner IIA and Block 5D-1 upper stage vehicles. A data base representing four different rocket motor designs (three spherical and one extended spherical) totaling twenty five three-axis stabilized firings is generated. Solid rocket motor time-varying resultant and lateral side force vector magnitudes, directions and total impulses, and roll torque couple magnitudes, directions, and total impulses are tabulated in the appendix. Population means and three sigma deviations are plotted. Existing applicable ground test side force and roll torque magnitudes and total impulses are evaluated and compared to the above experience data base. Within the spherical motor population, the selected AEDC ground test data consistently underestimated experienced motor side forces, roll torques and total impulses. Within the extended spherical motor population, the selected AEDC test data predicted experienced motor side forces, roll torques, and total impulses, with surprising accuracy considering the very small size of the test and experience populations.

Design optimization of dual-axis driving mechanism for satellite antenna with two planar revolute clearance joints

NASA Astrophysics Data System (ADS)

Bai, Zheng Feng; Zhao, Ji Jun; Chen, Jun; Zhao, Yang

2018-03-01

In the dynamic analysis of satellite antenna dual-axis driving mechanism, it is usually assumed that the joints are ideal or perfect without clearances. However, in reality, clearances in joints are unavoidable due to assemblage, manufacturing errors and wear. When clearance is introduced to the mechanism, it will lead to poor dynamic performances and undesirable vibrations due to impact forces in clearance joint. In this paper, a design optimization method is presented to reduce the undesirable vibrations of satellite antenna considering clearance joints in dual-axis driving mechanism. The contact force model in clearance joint is established using a nonlinear spring-damper model and the friction effect is considered using a modified Coulomb friction model. Firstly, the effects of clearances on dynamic responses of satellite antenna are investigated. Then the optimization method for dynamic design of the dual-axis driving mechanism with clearance is presented. The objective of the optimization is to minimize the maximum absolute vibration peak of antenna acceleration by reducing the impact forces in clearance joint. The main consideration here is to optimize the contact parameters of the joint elements. The contact stiffness coefficient, damping coefficient and the dynamic friction coefficient for clearance joint elements are taken as the optimization variables. A Generalized Reduced Gradient (GRG) algorithm is used to solve this highly nonlinear optimization problem for dual-axis driving mechanism with clearance joints. The results show that the acceleration peaks of satellite antenna and contact forces in clearance joints are reduced obviously after design optimization, which contributes to a better performance of the satellite antenna. Also, the application and limitation of the proposed optimization method are discussed.

Statistical considerations for grain-size analyses of tills

USGS Publications Warehouse

Jacobs, A.M.

1971-01-01

Relative percentages of sand, silt, and clay from samples of the same till unit are not identical because of different lithologies in the source areas, sorting in transport, random variation, and experimental error. Random variation and experimental error can be isolated from the other two as follows. For each particle-size class of each till unit, a standard population is determined by using a normally distributed, representative group of data. New measurements are compared with the standard population and, if they compare satisfactorily, the experimental error is not significant and random variation is within the expected range for the population. The outcome of the comparison depends on numerical criteria derived from a graphical method rather than on a more commonly used one-way analysis of variance with two treatments. If the number of samples and the standard deviation of the standard population are substituted in a t-test equation, a family of hyperbolas is generated, each of which corresponds to a specific number of subsamples taken from each new sample. The axes of the graphs of the hyperbolas are the standard deviation of new measurements (horizontal axis) and the difference between the means of the new measurements and the standard population (vertical axis). The area between the two branches of each hyperbola corresponds to a satisfactory comparison between the new measurements and the standard population. Measurements from a new sample can be tested by plotting their standard deviation vs. difference in means on axes containing a hyperbola corresponding to the specific number of subsamples used. If the point lies between the branches of the hyperbola, the measurements are considered reliable. But if the point lies outside this region, the measurements are repeated. Because the critical segment of the hyperbola is approximately a straight line parallel to the horizontal axis, the test is simplified to a comparison between the means of the standard population and the means of the subsample. The minimum number of subsamples required to prove significant variation between samples caused by different lithologies in the source areas and sorting in transport can be determined directly from the graphical method. The minimum number of subsamples required is the maximum number to be run for economy of effort. ?? 1971 Plenum Publishing Corporation.

Validation and uncertainty quantification of detector response functions for a 1″×2″ NaI collimated detector intended for inverse radioisotope source mapping applications

NASA Astrophysics Data System (ADS)

Nelson, N.; Azmy, Y.; Gardner, R. P.; Mattingly, J.; Smith, R.; Worrall, L. G.; Dewji, S.

2017-11-01

Detector response functions (DRFs) are often used for inverse analysis. We compute the DRF of a sodium iodide (NaI) nuclear material holdup field detector using the code named g03 developed by the Center for Engineering Applications of Radioisotopes (CEAR) at NC State University. Three measurement campaigns were performed in order to validate the DRF's constructed by g03: on-axis detection of calibration sources, off-axis measurements of a highly enriched uranium (HEU) disk, and on-axis measurements of the HEU disk with steel plates inserted between the source and the detector to provide attenuation. Furthermore, this work quantifies the uncertainty of the Monte Carlo simulations used in and with g03, as well as the uncertainties associated with each semi-empirical model employed in the full DRF representation. Overall, for the calibration source measurements, the response computed by the DRF for the prediction of the full-energy peak region of responses was good, i.e. within two standard deviations of the experimental response. In contrast, the DRF tended to overestimate the Compton continuum by about 45-65% due to inadequate tuning of the electron range multiplier fit variable that empirically represents physics associated with electron transport that is not modeled explicitly in g03. For the HEU disk measurements, computed DRF responses tended to significantly underestimate (more than 20%) the secondary full-energy peaks (any peak of lower energy than the highest-energy peak computed) due to scattering in the detector collimator and aluminum can, which is not included in the g03 model. We ran a sufficiently large number of histories to ensure for all of the Monte Carlo simulations that the statistical uncertainties were lower than their experimental counterpart's Poisson uncertainties. The uncertainties associated with least-squares fits to the experimental data tended to have parameter relative standard deviations lower than the peak channel relative standard deviation in most cases and good reduced chi-square values. The highest sources of uncertainty were identified as the energy calibration polynomial factor (due to limited source availability and NaI resolution) and the Ba-133 peak fit (only a very weak source was available), which were 20% and 10%, respectively.

On the secular decrease in the semimajor axis of Lageos orbit

NASA Technical Reports Server (NTRS)

Rubincam, D. P.

1980-01-01

The semimajor axis of the Lageos orbit is decreasing secularly at the rate of -1.1 mm/day due to an unknown force. Nine possible mechanisms are investigated. Five of the mechanisms, resonance with the Earth's gravitational field, gravitational radiation, the Poynting-Robertson effect, transfer of spin angular momentum to the orbital angular momentum, and drag from near Earth dust are ruled out because they are too small to require unacceptable assumptions to account for the observed rate. Three other mechanisms, the Yarkovsky effect, the Schach effect, and terrestrial radiation pressure could possibly give the proper order of magnitude for the decay rate, but the characteristic signatures of these perturbations do not agree with the observed secular decrease. Atmospheric drag from a combination of charged and neutral particles is the most likely cause for the orbital decay. This mechanism explains at least 71 percent of the observed rate of decrease of the semimajor axis.

Crystal alignments in the Fast ice of arctic Alaska

NASA Astrophysics Data System (ADS)

Weeks, W. F.; Gow, A. J.

1980-02-01

Field observations at 60 sites located in the fast or near-fast ice along a 1200-km stretch of the north coast of Alaska between the Bering Strait and Barter Island have shown that the great majority of the ice samples (95%) exhibit striking c axis alignments within the horizontal plane. In all cases the degree of preferred orientation increased with depth in the ice. Representative standard deviations around a mean direction in the horizontal plane are commonly less than ±10° for samples collected near the bottom of the ice. At a given site the mean c axis direction ?0 may vary as much as 20° with vertical location in the ice sheet. The c axis allignments in the nearshore region generally parallel the coast, with strong alignments occurring in the lagoon systems between the barrier islands and the coast and seaward of the barrier islands. In passes between islands and in entrances such as the opening to Kotzebue Sound the alignment is parallel to the channel. Only limited observations are available farther seaward over the inner (10- to 50-m isobaths) and outer (50-m isobath to shelf break) shelf regions. These indicate NE-SW and E-W alignments, respectively, in the Beaufort Sea north of Prudhoe Bay. The general patterns of the alignments support the correlation between the preferred c axis direction and the current direction at the ice/water interface suggested by Weeks and Gow (1978). A comparison between c axis alignments and instantaneous current measurements made at 42 locations shows that the most frequent current direction coincides with ?0. At the one site where we were able to determine the current direction (52°T) over a longer period (7 hours), the agreement with ?0. (48°T) was excellent. Similarly, if only ?0. values determined in the nearshore region are considered, the most frequent deviation is 10° or less between ?0. and the trend of the adjacent shoreline, which is presumably parallel to the prevailing longshore currents. The c axis alignments are believed to be the result of geometric selection, with the most favored orientation being that in which the current flows normal to the (0001) plates of ice that comprise the dendritic sea ice/seawater interface. The instantaneous current observations suggest SW nearshore currents along the Chukchi coast between SW of Point Lay and SW of the Rogers-Post Monument. In the vicinity of Barrow all currents measured along the Chukchi coast were toward the NE. Current directions along the Beaufort coast in the nearshore region were generally parallel to the coast, with 45% of the observations indicating currents toward the E and 55% currents toward the W.

Modification of the semitransparent Prunus serrula bark film: Making rubber out of bark

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

Xu, X.; Zaremba, C.; Stucky, G.D.

1998-11-01

The authors report an extensive structural and mechanical characterization of the semitransparent bark of Prunus serrula. Variations in the properties were observed. Mechanical properties along the fiber axis of these films are strongly related to the cell dimensions. Several trends can be seen with increasing cell length: tensile strength and Young`s modulus increase; ductility decreases. Perpendicular to the fiber axis, similar radial dimensions of the bark cells contributes to similar mechanical properties. Plasticization not only shrinks the dimension of the bulk films along the tangential axis, which is unique, but also dramatically changes the mechanical properties. The authors have shown,more » for the first time, that the mechanical properties of the Prunus serrula bark can be effectively tailored with different plasticization and modification agents. The plastic bark can be successfully converted to rubberlike material either temporally or permanently, or it can be strengthened by tensile deformation of the plasticized bark.« less

Determining the full halo coronal mass ejection characteristics

NASA Astrophysics Data System (ADS)

Fainshtein, V. G.

2009-03-01

In this paper we determined the parameters of 45 full halo coronal mass ejections (HCMEs) for various modifications of their cone forms (“ice cream cone models”). We show that the CME determined characteristics depend significantly on the CME chosen form. We show that, regardless of the CME chosen form, the trajectory of practically all the considered HCMEs deviate from the radial direction to the Sun-to-Earth axis at the initial stage of their movement.

4-Meth­oxy-N-(1-methyl-1H-indazol-5-yl)benzene­sulfonamide

PubMed Central

Chicha, Hakima; Rakib, El Mostapha; Geffken, Detlef; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

The indazole ring system [maximum deviation = 0.013 (2) Å] of the title compound, C15H15N3O3S, makes a dihedral angle of 50.11 (7)° with the benzene ring. In the crystal, cohesion is provided by C—H⋯O and N—H⋯N hydrogen bonds, which link the molecules into chains propagating along the b-axis direction. PMID:24427037

Principal components of wrist circumduction from electromagnetic surgical tracking.

PubMed

Rasquinha, Brian J; Rainbow, Michael J; Zec, Michelle L; Pichora, David R; Ellis, Randy E

2017-02-01

An electromagnetic (EM) surgical tracking system was used for a functionally calibrated kinematic analysis of wrist motion. Circumduction motions were tested for differences in subject gender and for differences in the sense of the circumduction as clockwise or counter-clockwise motion. Twenty subjects were instrumented for EM tracking. Flexion-extension motion was used to identify the functional axis. Subjects performed unconstrained wrist circumduction in a clockwise and counter-clockwise sense. Data were decomposed into orthogonal flexion-extension motions and radial-ulnar deviation motions. PCA was used to concisely represent motions. Nonparametric Wilcoxon tests were used to distinguish the groups. Flexion-extension motions were projected onto a direction axis with a root-mean-square error of [Formula: see text]. Using the first three principal components, there was no statistically significant difference in gender (all [Formula: see text]). For motion sense, radial-ulnar deviation distinguished the sense of circumduction in the first principal component ([Formula: see text]) and in the third principal component ([Formula: see text]); flexion-extension distinguished the sense in the second principal component ([Formula: see text]). The clockwise sense of circumduction could be distinguished by a multifactorial combination of components; there were no gender differences in this small population. These data constitute a baseline for normal wrist circumduction. The multifactorial PCA findings suggest that a higher-dimensional method, such as manifold analysis, may be a more concise way of representing circumduction in human joints.

The application of laser triangulation method on the blind guidance

NASA Astrophysics Data System (ADS)

Wu, Jih-Huah; Wang, Jinn-Der; Fang, Wei; Shan, Yi-Chia; Ma, Shih-Hsin; Kao, Hai-Ko; Jiang, Joe-Air; Lee, Yun-Parn

2011-08-01

A new apparatus for blind-guide is proposed in this paper. Optical triangulation method was used to realize the system. The main components comprise a notebook computer, a camera and two laser modules. One laser module emits a light line beam on the vertical axis. Another laser module emits a light line beam on the tilt horizontal axis. The track of the light line beam on the ground or on the object is captured by the camera, and the image is sent to the notebook computer for calculation. The system can calculate the object width and the distance between the object and the blind in terms of the light line positions on the image. Based on the experiment, the distance between the test object and the blind can be measured with a standard deviation of less than 3% within the range of 60 to 150 cm. The test object width can be measured with a standard deviation of less than 1% within the range of 60 to 150 cm. For saving the power consumption, the laser modules are switched on/off with a trigger pulse. And for reducing the complex computation, the two laser modules are switched on alternately. Besides this, a band pass filter is used to filter out the signal except the specific laser light, which can increase the signal to noise ratio.

Thrust vector control of upper stage with a gimbaled thruster during orbit transfer

NASA Astrophysics Data System (ADS)

Wang, Zhaohui; Jia, Yinghong; Jin, Lei; Duan, Jiajia

2016-10-01

In launching Multi-Satellite with One-Vehicle, the main thruster provided by the upper stage is mounted on a two-axis gimbal. During orbit transfer, the thrust vector of this gimbaled thruster (GT) should theoretically pass through the mass center of the upper stage and align with the command direction to provide orbit transfer impetus. However, it is hard to be implemented from the viewpoint of the engineering mission. The deviations of the thrust vector from the command direction would result in large velocity errors. Moreover, the deviations of the thrust vector from the upper stage mass center would produce large disturbance torques. This paper discusses the thrust vector control (TVC) of the upper stage during its orbit transfer. Firstly, the accurate nonlinear coupled kinematic and dynamic equations of the upper stage body, the two-axis gimbal and the GT are derived by taking the upper stage as a multi-body system. Then, a thrust vector control system consisting of the special attitude control of the upper stage and the gimbal rotation of the gimbaled thruster is proposed. The special attitude control defined by the desired attitude that draws the thrust vector to align with the command direction when the gimbal control makes the thrust vector passes through the upper stage mass center. Finally, the validity of the proposed method is verified through numerical simulations.

Climagramms as a Possibility of Evaluation of Hazards from Agrometeorological Point of View

NASA Astrophysics Data System (ADS)

Potop, V.; Kožnarová, V.; Klabzuba, J.; Turkott, L.

2009-04-01

This paper focuses particularly on the graphical method representation of the drought spells, which serves modeling of the time and spatial aspects of these events. In particular, we have applied Walter-Lieth's climograms and thermopluviograms in order to monitor and analyse droughts in an agrometeorological year (i.e. including the winter season). The latter provide a new design of evaluation of longer sequences from many years of observations. In other words, long time series can be evaluated by the thermopluviogram method exactly. We are proposing thermopluviogramm, which allows a combination of both the deviation of temperature from the long-term data and the percentage of long-term amounts of precipitation to be shown in the same graph. Modeling of thermopluviogramm has not been difficult. In the centre of this diagram we have placed the long term mean (or the standard period, e.g. 1961-1990) with the following coordinates: monthly average air temperature (x-axis) and monthly amount of precipitation (y-axis). Thus, the scale on the periphery shows the air temperature deviation from the long term mean and the percentage of the long term mean precipitation sum which makes the termopluviogramm applicable to any location worldwide. The basic diagram has been arranged as follows: The x-axis shows the average air temperature, with a 0.0o C deviation from the standard period (∆ t) marked in the centre of the graph. Depending on the size of deviation for a given period extreme conditions are indicated on the x-axis as follows: cold, very cold, extraordinary cold, normal, warm, very warm and extraordinary warm. The y-axis shows the amount of precipitation in a similar manner: the standard period value is 100%, which is also located in the centre of the graph. Below or upward this value, extreme conditions are shown: extraordinary dry, very dry, dry, normal, wet, very wet and extraordinary wet. Since the Zatec weather station is situated in the rain shadow of the "Krusne hory" (Ore Mountains) chain and is therefore in the driest region of the country, it was adopted as a reference station for the evaluations of the drought years. The assessment has been conducted on 47 years (1961-2007) of meteorological information recorded at the Czech Hydrometeorological Institute. According to Walter-Lieth's climagramms in a given part of the country, the drought spells have occurred during 59 months (which constituted 41 drought spells). Using the estimation of the statistical data on the basis of the climogramms we may distinguish 2 more cases with a total of 4-months of drought spells each, which can be divided into 1-2 periods respectively. One such case was noticed in 2003. This year the drought had begun in the month of June and had ended in October. Thus, the 2003 drought year was divided into 2 drought spells with a short interval between them. Conforming to thermopluviogramms, extraordinary drought years were recorded in the winter season for December: 2007, 1975, 1983, 1963, 1964; January: 2002, 1989, 1991 and 1971; and for February it was recorded in 1982. For the spring season extraordinary drought years were recorded in 1984 (March), 2007 and 1993 (April), 1998 (May). For the summer season extraordinary drought months were recorded only in July (1990 and 1964) and August (1973 and 2003). In the months of autumn they were recorded in October (1985) and November (2007). Keywords: thermopluviogramms, Walter-Lieth's climagramms, drought. Acknowledgements: This research was supported by Research Projects MSM No. 6046070901 and QH72257. Evaluation of agricultural soil fund with respect to environment protection".

Safety of long-term high-volume sinonasal budesonide irrigations for chronic rhinosinusitis.

PubMed

Smith, Kristine A; French, Gabrielle; Mechor, Bradford; Rudmik, Luke

2016-03-01

Off-label high-volume sinonasal budesonide irrigations are commonly used during the management of chronic rhinosinusitis (CRS). Although short-term use (4 to 8 weeks) has been demonstrated to be safe, the long-term effects on the hypothalamic-pituitary-adrenal (HPA) axis remain unclear. The objective of this study is to determine whether CRS patients using long-term (minimum greater than 12 months) budesonide sinonasal irrigations have evidence of HPA axis suppression. Patients with CRS being managed with high-volume sinonasal budesonide irrigations were recruited from 2 tertiary level rhinology clinics between March 2014 and July 2015. Inclusion criteria were as follows: (1) adult (age greater than 18 years); (2) guideline-based diagnosis of CRS; (3) previous endoscopic sinus surgery; (4) minimum of twice daily high-volume sinonasal budesonide irrigation (concentration of 1 mg per irrigation; total daily dose of 2 mg); and (5) a minimum of 12-month duration. Exclusion criteria included systemic corticosteroid use within 3 months of HPA axis testing. The primary outcomes were morning (am) serum cortisol levels and, when indicated, cosyntropin stimulation levels. A total of 35 patients fulfilled eligibility criteria and underwent HPA axis testing. Mean duration of budesonide sinonasal irrigation therapy use was 38.2 months (2.9 years). The mean ± standard deviation (SD) am serum cortisol was 431.2 ± 146.9 nmol/L (normal, 200 to 650 nmol/L). Subsequent cosyntropin stimulation tests, in indicated patients (n = 19), demonstrated no evidence of HPA axis suppression. Outcomes from this study suggest that daily high-volume sinonasal budesonide irrigations fail to produce evidence of HPA axis suppression with prolonged courses lasting longer than 2 years. © 2016 ARS-AAOA, LLC.

Mechanical Strain Determines Cilia Length, Motility, and Planar Position in the Left-Right Organizer.

PubMed

Chien, Yuan-Hung; Srinivasan, Shyam; Keller, Ray; Kintner, Chris

2018-05-07

The Xenopus left-right organizer (LRO) breaks symmetry along the left-right axis of the early embryo by producing and sensing directed ciliary flow as a patterning cue. To carry out this process, the LRO contains different ciliated cell types that vary in cilia length, whether they are motile or sensory, and how they position their cilia along the anterior-posterior (A-P) planar axis. Here, we show that these different cilia features are specified in the prospective LRO during gastrulation, based on anisotropic mechanical strain that is oriented along the A-P axis, and graded in levels along the medial-lateral axis. Strain instructs ciliated cell differentiation by acting on a mesodermal prepattern present at blastula stages, involving foxj1. We propose that differential strain is a graded, developmental cue, linking the establishment of an A-P planar axis to cilia length, motility, and planar location during formation of the Xenopus LRO. Copyright © 2018 Elsevier Inc. All rights reserved.

Deviations of the visual upright in three dimensions in disorders of the brainstem: a clinical exploration.

PubMed

Frisén, Lars

2010-12-01

Deviations of the subjective visual vertical in the roll or fronto-parallel plane occur commonly in disorders of the brainstem and have been extensively explored. In contrast, little is known about deviations in other directions. The present retrospective study focused on deviations in the pitch (sagittal) direction in 176 patients with a wide variety of disorders. The test task was to set a self-illuminated rod in the apparent upright position, in total darkness. Abnormal results (outside ± 4°) were recorded in 58% of the subjects. Negative (top backward) deviations were the most common, particularly with mass lesions in the pineal region, obstructive hydrocephalus, cerebellar lesions and crowding at the craniocervical junction. Positive and negative deviations were about equally common with focal intra-axial lesions. Negative deviations appeared related to dorsal locations of lesions and vice versa. Normal pressure hydrocephalus, Parkinson's disease and progressive supranuclear palsy were associated with smaller deviations, without a clear directional preponderance, and a larger individual variability. Most subjects lacked overt clinical corollaries. The most common ocular signs were aqueduct syndromes (n = 17) and ocular tilt reactions (n = 12), which were associated with deviations in 47 and 92% of instances, respectively. Subjective corollaries of deviation were never reported, not even by those subjects who showed a dramatic improvement upon resolution of the underlying condition. Deviations were also assessed in roll in a subgroup of 40 patients with focal lesions. Thirty subjects returned abnormal results: 13% in roll, 47% in pitch and 40% in pitch and roll. The direction of roll deviation appeared primarily related to laterality, with clockwise deviations with right-sided lesions and vice versa. All subjects with ocular tilt reactions had combined pitch and roll deviations, implying a common neural substrate. Correlation analyses, geometrical modelling and experimental self-observations indicated that deviations in pitch were attributable to cyclotorsional asymmetries between the eyes. The frequent co-existence of abnormal pitch and roll results implies that the true axis of deviation in focal brainstem disorders commonly falls outside traditional reference planes. The term 'visual upright in three dimensions' is suggested to identify unrestricted measurements, preserving the established term 'visual vertical' for measurements confined to the roll plane. Assessment of the visual upright in three dimensions provides a new, quantitative angle on brainstem disorders. The test appears useful for identifying a ubiquitous yet clinically silent feature of brainstem disease and also for monitoring the evolution of underlying conditions. More detailed explorations appear well motivated.

β-Catenin is essential for patterning the maternally specified animal-vegetal axis in the sea urchin embryo

PubMed Central

Wikramanayake, Athula H.; Huang, Ling; Klein, William H.

1998-01-01

In sea urchin embryos, the animal-vegetal axis is specified during oogenesis. After fertilization, this axis is patterned to produce five distinct territories by the 60-cell stage. Territorial specification is thought to occur by a signal transduction cascade that is initiated by the large micromeres located at the vegetal pole. The molecular mechanisms that mediate the specification events along the animal–vegetal axis in sea urchin embryos are largely unknown. Nuclear β-catenin is seen in vegetal cells of the early embryo, suggesting that this protein plays a role in specifying vegetal cell fates. Here, we test this hypothesis and show that β-catenin is necessary for vegetal plate specification and is also sufficient for endoderm formation. In addition, we show that β-catenin has pronounced effects on animal blastomeres and is critical for specification of aboral ectoderm and for ectoderm patterning, presumably via a noncell-autonomous mechanism. These results support a model in which a Wnt-like signal released by vegetal cells patterns the early embryo along the animal–vegetal axis. Our results also reveal similarities between the sea urchin animal–vegetal axis and the vertebrate dorsal–ventral axis, suggesting that these axes share a common evolutionary origin. PMID:9689082

Repeatability and oblique flow response characteristics of current meters

USGS Publications Warehouse

Fulford, Janice M.; Thibodeaux, Kirk G.; Kaehrle, William R.; ,

1993-01-01

Laboratory investigation into the precision and accuracy of various mechanical-current meters are presented. Horizontal-axis and vertical-axis meters that are used for the measurement of point velocities in streams and rivers were tested. Meters were tested for repeatability and response to oblique flows. Both horizontal- and vertical-axis meters were found to under- and over-register oblique flows with errors generally increasing as the velocity and angle of flow increased. For the oblique flow tests, magnitude of errors were smallest for horizontal-axis meters. Repeatability of all meters tested was good, with the horizontal- and vertical-axis meters performing similarly.

Left and right ventricular hemodynamic forces in healthy volunteers and elite athletes assessed with 4D flow magnetic resonance imaging.

PubMed

Arvidsson, Per M; Töger, Johannes; Carlsson, Marcus; Steding-Ehrenborg, Katarina; Pedrizzetti, Gianni; Heiberg, Einar; Arheden, Håkan

2017-02-01

Intracardiac blood flow is driven by hemodynamic forces that are exchanged between the blood and myocardium. Previous studies have been limited to 2D measurements or investigated only left ventricular (LV) forces. Right ventricular (RV) forces and their mechanistic contribution to asymmetric redirection of flow in the RV have not been measured. We therefore aimed to quantify 3D hemodynamic forces in both ventricles in a cohort of healthy subjects, using magnetic resonance imaging 4D flow measurements. Twenty five controls, 14 elite endurance athletes, and 2 patients with LV dyssynchrony were included. 4D flow data were used as input for the Navier-Stokes equations to compute hemodynamic forces over the entire cardiac cycle. Hemodynamic forces were found in a qualitatively consistent pattern in all healthy subjects, with variations in amplitude. LV forces were mainly aligned along the apical-basal longitudinal axis, with an additional component aimed toward the aortic valve during systole. Conversely, RV forces were found in both longitudinal and short-axis planes, with a systolic force component driving a slingshot-like acceleration that explains the mechanism behind the redirection of blood flow toward the pulmonary valve. No differences were found between controls and athletes when indexing forces to ventricular volumes, indicating that cardiac force expenditures are tuned to accelerate blood similarly in small and large hearts. Patients' forces differed from controls in both timing and amplitude. Normal cardiac pumping is associated with specific force patterns for both ventricles, and deviation from these forces may be a sensitive marker of ventricular dysfunction. Reference values are provided for future studies. NEW & NOTEWORTHY Biventricular hemodynamic forces were quantified for the first time in healthy controls and elite athletes (n = 39). Hemodynamic forces constitute a slingshot-like mechanism in the right ventricle, redirecting blood flow toward the pulmonary circulation. Force patterns were similar between healthy subjects and athletes, indicating potential utility as a cardiac function biomarker. Copyright © 2017 the American Physiological Society.

Role of muscle pulleys in producing eye position-dependence in the angular vestibuloocular reflex: a model-based study

NASA Technical Reports Server (NTRS)

Thurtell, M. J.; Kunin, M.; Raphan, T.; Wall, C. C. (Principal Investigator)

2000-01-01

It is well established that the head and eye velocity axes do not always align during compensatory vestibular slow phases. It has been shown that the eye velocity axis systematically tilts away from the head velocity axis in a manner that is dependent on eye-in-head position. The mechanisms responsible for producing these axis tilts are unclear. In this model-based study, we aimed to determine whether muscle pulleys could be involved in bringing about these phenomena. The model presented incorporates semicircular canals, central vestibular pathways, and an ocular motor plant with pulleys. The pulleys were modeled so that they brought about a rotation of the torque axes of the extraocular muscles that was a fraction of the angle of eye deviation from primary position. The degree to which the pulleys rotated the torque axes was altered by means of a pulley coefficient. Model input was head velocity and initial eye position data from passive and active yaw head impulses with fixation at 0 degrees, 20 degrees up and 20 degrees down, obtained from a previous experiment. The optimal pulley coefficient required to fit the data was determined by calculating the mean square error between data and model predictions of torsional eye velocity. For active head impulses, the optimal pulley coefficient varied considerably between subjects. The median optimal pulley coefficient was found to be 0.5, the pulley coefficient required for producing saccades that perfectly obey Listing's law when using a two-dimensional saccadic pulse signal. The model predicted the direction of the axis tilts observed in response to passive head impulses from 50 ms after onset. During passive head impulses, the median optimal pulley coefficient was found to be 0.21, when roll gain was fixed at 0.7. The model did not accurately predict the alignment of the eye and head velocity axes that was observed early in the response to passive head impulses. We found that this alignment could be well predicted if the roll gain of the angular vestibuloocular reflex was modified during the initial period of the response, while pulley coefficient was maintained at 0.5. Hence a roll gain modification allows stabilization of the retinal image without requiring a change in the pulley effect. Our results therefore indicate that the eye position-dependent velocity axis tilts could arise due to the effects of the pulleys and that a roll gain modification in the central vestibular structures may be responsible for countering the pulley effect.

CARS Temperature Measurements in a Combustion-Heated Supersonic Jet

NASA Technical Reports Server (NTRS)

Tedder, S. A.; Danehy, P. M.; Magnotti, G.; Cutler, A. D.

2009-01-01

Measurements were made in a combustion-heated supersonic axi-symmetric free jet from a nozzle with a diameter of 6.35 cm using dual-pump Coherent Anti-Stokes Raman Spectroscopy (CARS). The resulting mean and standard deviation temperature maps are presented. The temperature results show that the gas temperature on the centerline remains constant for approximately 5 nozzle diameters. As the heated gas mixes with the ambient air further downstream the mean temperature decreases. The standard deviation map shows evidence of the increase of turbulence in the shear layer as the jet proceeds downstream and mixes with the ambient air. The challenges of collecting data in a harsh environment are discussed along with influences to the data. The yield of the data collected is presented and possible improvements to the yield is presented are discussed.

Mechanical behavior and fracture characteristics of off-axis fiber composites. 1: Experimental investigation. [at the Lewis Research Center

NASA Technical Reports Server (NTRS)

Sinclair, J. H.; Chamis, C. C.

1977-01-01

The mechanical behavior, fracture surfaces, and fracture modes of unidirectional high-modulus graphite-fiber/epoxy composites subjected to off-axis tensile loads were investigated experimentally. The investigation included the generation of stress-strain-to-fracture data and scanning electron microscope studies of the fractured surfaces. The results led to the identification of fracture modes and distinct fracture surface characteristics for off-axis tensile loading. The results also led to the formulation of critical for identifying and characterizing these fracture modes and their associated fracture surfaces. The results presented and discussed herein were used in the theoretical investigation and comparisons described in Part 2. These results should also provide a good foundation for identifying, characterizing, and quantifying fracture modes in both off-axis and angle-plied laminates.

5 V Compatible Two-Axis PZT Driven MEMS Scanning Mirror with Mechanical Leverage Structure for Miniature LiDAR Application.

PubMed

Ye, Liangchen; Zhang, Gaofei; You, Zheng

2017-03-05

The MEMS (Micro-Electronical Mechanical System) scanning mirror is an optical MEMS device that can scan laser beams across one or two dimensions. MEMS scanning mirrors can be applied in a variety of applications, such as laser display, bio-medical imaging and Light Detection and Ranging (LiDAR). These commercial applications have recently created a great demand for low-driving-voltage and low-power MEMS mirrors. However, no reported two-axis MEMS scanning mirror is available for usage in a universal supplying voltage such as 5 V. In this paper, we present an ultra-low voltage driven two-axis MEMS scanning mirror which is 5 V compatible. In order to realize low voltage and low power, a two-axis MEMS scanning mirror with mechanical leverage driven by PZT (Lead zirconate titanate) ceramic is designed, modeled, fabricated and characterized. To further decrease the power of the MEMS scanning mirror, a new method of impedance matching for PZT ceramic driven by a two-frequency mixed signal is established. As experimental results show, this MEMS scanning mirror reaches a two-axis scanning angle of 41.9° × 40.3° at a total driving voltage of 4.2 Vpp and total power of 16 mW. The effective diameter of reflection of the mirror is 2 mm and the operating frequencies of two-axis scanning are 947.51 Hz and 1464.66 Hz, respectively.

5 V Compatible Two-Axis PZT Driven MEMS Scanning Mirror with Mechanical Leverage Structure for Miniature LiDAR Application

PubMed Central

Ye, Liangchen; Zhang, Gaofei; You, Zheng

2017-01-01

The MEMS (Micro-Electronical Mechanical System) scanning mirror is an optical MEMS device that can scan laser beams across one or two dimensions. MEMS scanning mirrors can be applied in a variety of applications, such as laser display, bio-medical imaging and Light Detection and Ranging (LiDAR). These commercial applications have recently created a great demand for low-driving-voltage and low-power MEMS mirrors. However, no reported two-axis MEMS scanning mirror is available for usage in a universal supplying voltage such as 5 V. In this paper, we present an ultra-low voltage driven two-axis MEMS scanning mirror which is 5 V compatible. In order to realize low voltage and low power, a two-axis MEMS scanning mirror with mechanical leverage driven by PZT (Lead zirconate titanate) ceramic is designed, modeled, fabricated and characterized. To further decrease the power of the MEMS scanning mirror, a new method of impedance matching for PZT ceramic driven by a two-frequency mixed signal is established. As experimental results show, this MEMS scanning mirror reaches a two-axis scanning angle of 41.9° × 40.3° at a total driving voltage of 4.2 Vpp and total power of 16 mW. The effective diameter of reflection of the mirror is 2 mm and the operating frequencies of two-axis scanning are 947.51 Hz and 1464.66 Hz, respectively. PMID:28273880

[Comparisons of manual and automatic refractometry with subjective results].

PubMed

Wübbolt, I S; von Alven, S; Hülssner, O; Erb, C

2006-11-01

Refractometry is very important in everyday clinical practice. The aim of this study is to compare the precision of three objective methods of refractometry with subjective dioptometry (Phoropter). The objective methods with the smallest deviation to subjective refractometry results are evaluated. The objective methods/instruments used were retinoscopy, Prism Refractometer PR 60 (Rodenstock) and Auto Refractometer RM-A 7000 (Topcon). The results of monocular dioptometry (sphere, cylinder and axis) of each objective method were compared to the results of the subjective method. The examination was carried out on 178 eyes, which were divided into 3 age-related groups: 6 - 12 years (103 eyes), 13 - 18 years (38 eyes) and older than 18 years (37 eyes). All measurements were made in cycloplegia. The smallest standard deviation of the measurement error was found for the Auto Refractometer RM-A 7000. Both the PR 60 and retinoscopy had a clearly higher standard deviation. Furthermore, the RM-A 7000 showed in three and retinoscopy in four of the nine comparisons a significant bias in the measurement error. The Auto Refractometer provides measurements with the smallest deviation compared to the subjective method. Here it has to be taken into account that the measurements for the sphere have an average deviation of + 0.2 dpt. In comparison to retinoscopy the examination of children with the RM-A 7000 is difficult. An advantage of the Auto Refractometer is the fast and easy handling, so that measurements can be performed by medical staff.

Application of external axis in thermal spraying

NASA Astrophysics Data System (ADS)

Gao, Guoyou; Wang, Wei; Chen, Tao; Hui, Chun

2018-05-01

Industrial robots are widely used nowadays in the process of thermal spraying, human work can be largely replaced due to the high-efficient, security, precision and repeatability of industrial robot. As offering the convenience to industrial product, Robots have some natural deficiencies because of its mechanical linkages of six-axis. When robot performs a series of stage of production, it could be hard to move to the next one because one of his axis reaches a maximum value. For this reason, external axis is added to robot system to extend the reachable space of robot axis. This paper concerns to the application of external axis and the different methods of programming the robot with work-holding external axis in the virtual environment. Experiments demonstrate the coating layer on the regular workpiece is uniform.

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

Chen, Chin-Cheng, E-mail: chen.ccc@gmail.com; Chang, Chang; Mah, Dennis

Purpose: The spot characteristics for proton pencil beam scanning (PBS) were measured and analyzed over a 16 month period, which included one major site configuration update and six cyclotron interventions. The results provide a reference to establish the quality assurance (QA) frequency and tolerance for proton pencil beam scanning. Methods: A simple treatment plan was generated to produce an asymmetric 9-spot pattern distributed throughout a field of 16 × 18 cm for each of 18 proton energies (100.0–226.0 MeV). The delivered fluence distribution in air was measured using a phosphor screen based CCD camera at three planes perpendicular to themore » beam line axis (x-ray imaging isocenter and up/down stream 15.0 cm). The measured fluence distributions for each energy were analyzed using in-house programs which calculated the spot sizes and positional deviations of the Gaussian shaped spots. Results: Compared to the spot characteristic data installed into the treatment planning system, the 16-month averaged deviations of the measured spot sizes at the isocenter plane were 2.30% and 1.38% in the IEC gantry x and y directions, respectively. The maximum deviation was 12.87% while the minimum deviation was 0.003%, both at the upstream plane. After the collinearity of the proton and x-ray imaging system isocenters was optimized, the positional deviations of the spots were all within 1.5 mm for all three planes. During the site configuration update, spot positions were found to deviate by 6 mm until the tuning parameters file was properly restored. Conclusions: For this beam delivery system, it is recommended to perform a spot size and position check at least monthly and any time after a database update or cyclotron intervention occurs. A spot size deviation tolerance of <15% can be easily met with this delivery system. Deviations of spot positions were <2 mm at any plane up/down stream 15 cm from the isocenter.« less

Technical Note: Spot characteristic stability for proton pencil beam scanning.

PubMed

Chen, Chin-Cheng; Chang, Chang; Moyers, Michael F; Gao, Mingcheng; Mah, Dennis

2016-02-01

The spot characteristics for proton pencil beam scanning (PBS) were measured and analyzed over a 16 month period, which included one major site configuration update and six cyclotron interventions. The results provide a reference to establish the quality assurance (QA) frequency and tolerance for proton pencil beam scanning. A simple treatment plan was generated to produce an asymmetric 9-spot pattern distributed throughout a field of 16 × 18 cm for each of 18 proton energies (100.0-226.0 MeV). The delivered fluence distribution in air was measured using a phosphor screen based CCD camera at three planes perpendicular to the beam line axis (x-ray imaging isocenter and up/down stream 15.0 cm). The measured fluence distributions for each energy were analyzed using in-house programs which calculated the spot sizes and positional deviations of the Gaussian shaped spots. Compared to the spot characteristic data installed into the treatment planning system, the 16-month averaged deviations of the measured spot sizes at the isocenter plane were 2.30% and 1.38% in the IEC gantry x and y directions, respectively. The maximum deviation was 12.87% while the minimum deviation was 0.003%, both at the upstream plane. After the collinearity of the proton and x-ray imaging system isocenters was optimized, the positional deviations of the spots were all within 1.5 mm for all three planes. During the site configuration update, spot positions were found to deviate by 6 mm until the tuning parameters file was properly restored. For this beam delivery system, it is recommended to perform a spot size and position check at least monthly and any time after a database update or cyclotron intervention occurs. A spot size deviation tolerance of <15% can be easily met with this delivery system. Deviations of spot positions were <2 mm at any plane up/down stream 15 cm from the isocenter.

High-accuracy self-calibration method for dual-axis rotation-modulating RLG-INS

NASA Astrophysics Data System (ADS)

Wei, Guo; Gao, Chunfeng; Wang, Qi; Wang, Qun; Long, Xingwu

2017-05-01

Inertial navigation system has been the core component of both military and civil navigation systems. Dual-axis rotation modulation can completely eliminate the inertial elements constant errors of the three axes to improve the system accuracy. But the error caused by the misalignment angles and the scale factor error cannot be eliminated through dual-axis rotation modulation. And discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed the effect of calibration error during one modulated period and presented a new systematic self-calibration method for dual-axis rotation-modulating RLG-INS. Procedure for self-calibration of dual-axis rotation-modulating RLG-INS has been designed. The results of self-calibration simulation experiment proved that: this scheme can estimate all the errors in the calibration error model, the calibration precision of the inertial sensors scale factor error is less than 1ppm and the misalignment is less than 5″. These results have validated the systematic self-calibration method and proved its importance for accuracy improvement of dual -axis rotation inertial navigation system with mechanically dithered ring laser gyroscope.

Normal dimensions of the posterior pituitary bright spot on magnetic resonance imaging.

PubMed

Côté, Martin; Salzman, Karen L; Sorour, Mohammad; Couldwell, William T

2014-02-01

The normal pituitary bright spot seen on unenhanced T1-weighted MRI is thought to result from the T1-shortening effect of the vasopressin stored in the posterior pituitary. Individual variations in its size may be difficult to differentiate from pathological conditions resulting in either absence of the pituitary bright spot or in T1-hyperintense lesions of the sella. The objective of this paper was to define a range of normal dimensions of the pituitary bright spot and to illustrate some of the most commonly encountered pathologies that result in absence or enlargement of the pituitary bright spot. The authors selected normal pituitary MRI studies from 106 patients with no pituitary abnormality. The size of each pituitary bright spot was measured in the longest axis and in the dimension perpendicular to this axis to describe the typical dimensions. The authors also present cases of patients with pituitary abnormalities to highlight the differences and potential overlap between normal and pathological pituitary imaging. All of the studies evaluated were found to have pituitary bright spots, and the mean dimensions were 4.8 mm in the long axis and 2.4 mm in the short axis. The dimension of the pituitary bright spot in the long axis decreased with patient age. The distribution of dimensions of the pituitary bright spot was normal, indicating that 99.7% of patients should have a pituitary bright spot measuring between 1.2 and 8.5 mm in its long axis and between 0.4 and 4.4 mm in its short axis, an interval corresponding to 3 standard deviations below and above the mean. In cases where the dimension of the pituitary bright spot is outside this range, pathological conditions should be considered. The pituitary bright spot should always be demonstrated on T1-weighted MRI, and its dimensions should be within the identified normal range in most patients. Outside of this range, pathological conditions affecting the pituitary bright spot should be considered.

Silencing of Smed-betacatenin1 generates radial-like hypercephalized planarians.

PubMed

Iglesias, Marta; Gomez-Skarmeta, Jose Luis; Saló, Emili; Adell, Teresa

2008-04-01

Little is known about the molecular mechanisms responsible for axis establishment during non-embryonic processes such as regeneration and homeostasis. To address this issue, we set out to analyze the role of the canonical Wnt pathway in planarians, flatworms renowned for their extraordinary morphological plasticity. Canonical Wnt signalling is an evolutionarily conserved mechanism to confer polarity during embryonic development, specifying the anteroposterior (AP) axis in most bilaterians and the dorsoventral (DV) axis in early vertebrate embryos. beta-Catenin is a key element in this pathway, although it is a bifunctional protein that is also involved in cell-cell adhesion. Here, we report the characterization of two beta-catenin homologs from Schmidtea mediterranea (Smed-betacatenin1/2). Loss of function of Smed-betacatenin1, but not Smed-betacatenin2, in both regenerating and intact planarians, generates radial-like hypercephalized planarians in which the AP axis disappears but the DV axis remains unaffected, representing a unique example of a striking body symmetry transformation. The radial-like hypercephalized phenotype demonstrates the requirement for Smed-betacatenin1 in AP axis re-establishment and maintenance, and supports a conserved role for canonical Wnt signalling in AP axis specification, whereas the role of beta-catenin in DV axis establishment would be a vertebrate innovation. When considered alongside the protein domains present in each S. mediterranea beta-catenin and the results of functional assays in Xenopus embryos demonstrating nuclear accumulation and axis induction with Smed-betacatenin1, but not Smed-betacatenin2, these data suggest that S. mediterranea beta-catenins could be functionally specialized and that only Smed-betacatenin1 is involved in Wnt signalling.

Fluid-driven fracture propagation in heterogeneous media: Probability distributions of fracture trajectories

NASA Astrophysics Data System (ADS)

Santillán, David; Mosquera, Juan-Carlos; Cueto-Felgueroso, Luis

2017-11-01

Hydraulic fracture trajectories in rocks and other materials are highly affected by spatial heterogeneity in their mechanical properties. Understanding the complexity and structure of fluid-driven fractures and their deviation from the predictions of homogenized theories is a practical problem in engineering and geoscience. We conduct a Monte Carlo simulation study to characterize the influence of heterogeneous mechanical properties on the trajectories of hydraulic fractures propagating in elastic media. We generate a large number of random fields of mechanical properties and simulate pressure-driven fracture propagation using a phase-field model. We model the mechanical response of the material as that of an elastic isotropic material with heterogeneous Young modulus and Griffith energy release rate, assuming that fractures propagate in the toughness-dominated regime. Our study shows that the variance and the spatial covariance of the mechanical properties are controlling factors in the tortuousness of the fracture paths. We characterize the deviation of fracture paths from the homogenous case statistically, and conclude that the maximum deviation grows linearly with the distance from the injection point. Additionally, fracture path deviations seem to be normally distributed, suggesting that fracture propagation in the toughness-dominated regime may be described as a random walk.

Fluid-driven fracture propagation in heterogeneous media: Probability distributions of fracture trajectories.

PubMed

Santillán, David; Mosquera, Juan-Carlos; Cueto-Felgueroso, Luis

2017-11-01

Hydraulic fracture trajectories in rocks and other materials are highly affected by spatial heterogeneity in their mechanical properties. Understanding the complexity and structure of fluid-driven fractures and their deviation from the predictions of homogenized theories is a practical problem in engineering and geoscience. We conduct a Monte Carlo simulation study to characterize the influence of heterogeneous mechanical properties on the trajectories of hydraulic fractures propagating in elastic media. We generate a large number of random fields of mechanical properties and simulate pressure-driven fracture propagation using a phase-field model. We model the mechanical response of the material as that of an elastic isotropic material with heterogeneous Young modulus and Griffith energy release rate, assuming that fractures propagate in the toughness-dominated regime. Our study shows that the variance and the spatial covariance of the mechanical properties are controlling factors in the tortuousness of the fracture paths. We characterize the deviation of fracture paths from the homogenous case statistically, and conclude that the maximum deviation grows linearly with the distance from the injection point. Additionally, fracture path deviations seem to be normally distributed, suggesting that fracture propagation in the toughness-dominated regime may be described as a random walk.

A novel determination of energy expenditure efficiency during a balance task using accelerometers. A pilot study.

PubMed

Caña-Pino, Alejandro; Apolo-Arenas, Maria Dolores; Moral-Blanco, Javier; De la Cruz-Sánchez, Ernesto; Espejo-Antúnez, Luis

2017-08-18

The objectives of this study are to determine the displacement of the center of pressure (CoP) and its association with the spectral energy density of the acceleration required for the maintenance of postural balance in different standing positions in healthy participants using design observational and setting laboratorial studies. Participants were 30 healthy university students aged between 18 and 32 years old (mean [M] ± standard deviation [SD] = 21,57 ± 3,31 years). Triaxial accelerometer and a pressure platform were used in order to obtain energy spectral density and CoP sway measurements during four balance tasks. Statistically significant differences were found for anteroposterior (p = 0.002) and mediolateral (p = 0.009) CoP displacement between the conditions eyes closed and stable surface and the conditions eyes closed and unstable surface. A statistically significant correlation was also observed between Z-axis (anterior-posterior) of the accelerometer and mediolateral axis of the CoP (r = 0.465; p = 0.01) and between Y-axis accelerometer (mediolateral) and displacement of the CoP in the anteroposterior axis (r = 0.413; p = 0.023). Spectral energy density appears to be associated with the displacement of CoP in healthy participants.

Mechanisms of strain accommodation in plastically-deformed zircon under simple shear deformation conditions during amphibolite-facies metamorphism

NASA Astrophysics Data System (ADS)

Kovaleva, Elizaveta; Klötzli, Urs; Wheeler, John; Habler, Gerlinde

2018-02-01

This study documents the strain accommodation mechanisms in zircon under amphibolite-facies metamorphic conditions in simple shear. Microstructural data from undeformed, fractured and crystal-plastically deformed zircon crystals are described in the context of the host shear zone, and evaluated in the light of zircon elastic anisotropy. Our work challenges the existing model of zircon evolution and shows previously undescribed rheological characteristics for this important accessory mineral. Crystal-plastically deformed zircon grains have axis oriented parallel to the foliation plane, with the majority of deformed grains having axis parallel to the lineation. Zircon accommodates strain by a network of stepped low-angle boundaries, formed by switching between tilt dislocations with the slip systems <100>{010} and < 1 bar 10>{110} and rotation axis [001], twist dislocations with the rotation axis [001], and tilt dislocations with the slip system <100>{001} and rotation axis [010]. The slip system < 1 bar 10>{110} is newly described for zircon. Most misorientation axes in plastically-deformed zircon grains are parallel to the XY plane of the sample and have [001] crystallographic direction. Such behaviour of strained zircon lattice is caused by elastic anisotropy that has a direct geometric control on the rheology, deformation mechanisms and dominant slip systems in zircon. Young's modulus and P wave velocity have highest values parallel to zircon [001] axis, indicating that zircon is elastically strong along this direction. Poisson ratio and Shear modulus demonstrate that zircon is also most resistant to shearing along [001]. Thus, [001] axis is the most common rotation axis in zircon. The described zircon behaviour is important to take into account during structural and geochronological investigations of (poly)metamorphic terrains. Geometry of dislocations in zircon may help reconstructing the geometry of the host shear zone(s), large-scale stresses in the crust, and, possibly, the timing of deformation, if the isotopic systems of deformed zircon were reset.

Cholesteric pitch transitions induced by mechanical strain.

PubMed

Lelidis, I; Barbero, G; Alexe-Ionescu, A L

2013-02-01

We investigate thickness and surface anchoring strength influence on pitch transitions in a planar cholesteric liquid crystal layer. The cholesteric-nematic transition is also investigated. We assume planar boundary conditions, with strong anchoring strength at one interface and weak anchoring strength at the other. The surface anchoring energy we consider to describe the deviation of the surface twist angle from the easy axis induced by a bulk deformation is a parabolic potential or Rapini and Papoular periodic potential, respectively. We show that under strain, all pitch transitions take place at a critical thickness that is equal to the quarter of the natural cholesteric pitch. The latter result does not depend on the anchoring strength, the particular surface potential, or material properties. The twist angle on the limiting surface characterized by weak anchoring varies with strain either by slipping and or in a discontinuous manner according to the thickness of the sample. The position of the bifurcation point depends only on the ratio of the extrapolation length over the layer thickness, but its value is model dependent. Multistability and multiplicity of the transition are discussed.

NF-κB Immunity in the Brain Determines Fly Lifespan in Healthy Aging and Age-Related Neurodegeneration.

PubMed

Kounatidis, Ilias; Chtarbanova, Stanislava; Cao, Yang; Hayne, Margaret; Jayanth, Dhruv; Ganetzky, Barry; Ligoxygakis, Petros

2017-04-25

During aging, innate immunity progresses to a chronically active state. However, what distinguishes those that "age well" from those developing age-related neurological conditions is unclear. We used Drosophila to explore the cost of immunity in the aging brain. We show that mutations in intracellular negative regulators of the IMD/NF-κB pathway predisposed flies to toxic levels of antimicrobial peptides, resulting in early locomotor defects, extensive neurodegeneration, and reduced lifespan. These phenotypes were rescued when immunity was suppressed in glia. In healthy flies, suppressing immunity in glial cells resulted in increased adipokinetic hormonal signaling with high nutrient levels in later life and an extension of active lifespan. Thus, when levels of IMD/NF-κB deviate from normal, two mechanisms are at play: lower levels derepress an immune-endocrine axis, which mobilizes nutrients, leading to lifespan extension, whereas higher levels increase antimicrobial peptides, causing neurodegeneration. Immunity in the fly brain is therefore a key lifespan determinant. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

A new wind energy conversion system

NASA Technical Reports Server (NTRS)

Smetana, F. O.

1975-01-01

It is presupposed that vertical axis wind energy machines will be superior to horizontal axis machines on a power output/cost basis and the design of a new wind energy machine is presented. The design employs conical cones with sharp lips and smooth surfaces to promote maximum drag and minimize skin friction. The cones are mounted on a vertical axis in such a way as to assist torque development. Storing wind energy as compressed air is thought to be optimal and reasons are: (1) the efficiency of compression is fairly high compared to the conversion of mechanical energy to electrical energy in storage batteries; (2) the release of stored energy through an air motor has high efficiency; and (3) design, construction, and maintenance of an all-mechanical system is usually simpler than for a mechanical to electrical conversion system.

High strain rate properties of off-axis composite laminates, part 2

NASA Technical Reports Server (NTRS)

Daniel, I. M.

1991-01-01

Unidirectional off-axis graphite/epoxy and graphite/S-glass/epoxy laminates were characterized in uniaxial tension at strain rates ranging from quasi-static to over 500 s(sup -1). Laminate ring specimens were loaded by internal pressure with the tensile stress at 22.5, 30, and 45 degrees relative to the fiber direction. Results were presented in the form of stress-strain curves to failure. Properties determined included moduli, Poisson's ratios, strength, and ultimate strain. In all three laminates of both materials the modulus and strength increase sharply with strain rate, reaching values roughly 100, 150, and 200 percent higher than corresponding static values for the 22.5(sub 8), 30(sub 8), and 45(sub 8) degree laminates, respectively. In the case of ultimate strain no definite trends could be established, but the maximum deviation from the average of any value for any strain rate was less than 18 percent.

Orientation illusions and heart-rate changes during short-radius centrifugation

NASA Technical Reports Server (NTRS)

Hecht, H.; Kavelaars, J.; Cheung, C. C.; Young, L. R.

2001-01-01

Intermittent short-radius centrifugation is a promising countermeasure against the adverse effects of prolonged weightlessness. To assess the feasibility of this countermeasure, we need to understand the disturbing sensory effects that accompany some movements carried out during rotation. We tested 20 subjects who executed yaw and pitch head movements while rotating at constant angular velocity. They were supine with their main body axis perpendicular to earth gravity. The head was placed at the centrifuge's axis of rotation. Head movements produced a transient elevation of heart-rate. All observers reported head-contingent sensations of body tilt although their bodies remained supine. Mostly, the subjective sensations conform to a model based on semicircular canal responses to angular acceleration. However, some surprising deviations from the model were found. Also, large inter-individual differences in direction, magnitude, and quality of the illusory body tilt were observed. The results have implications for subject screening and prediction of subjective tolerance for centrifugation.

Dynamic Modeling of Starting Aerodynamics and Stage Matching in an Axi-Centrifugal Compressor

NASA Technical Reports Server (NTRS)

Wilkes, Kevin; OBrien, Walter F.; Owen, A. Karl

1996-01-01

A DYNamic Turbine Engine Compressor Code (DYNTECC) has been modified to model speed transients from 0-100% of compressor design speed. The impetus for this enhancement was to investigate stage matching and stalling behavior during a start sequence as compared to rotating stall events above ground idle. The model can simulate speed and throttle excursions simultaneously as well as time varying bleed flow schedules. Results of a start simulation are presented and compared to experimental data obtained from an axi-centrifugal turboshaft engine and companion compressor rig. Stage by stage comparisons reveal the front stages to be operating in or near rotating stall through most of the start sequence. The model matches the starting operating line quite well in the forward stages with deviations appearing in the rearward stages near the start bleed. Overall, the performance of the model is very promising and adds significantly to the dynamic simulation capabilities of DYNTECC.

N-(2-Allyl-4-chloro-2H-indazol-5-yl)-4-meth­oxy­benzene­sulfonamide hemi­hydrate

PubMed Central

Chicha, Hakima; Kouakou, Assoman; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

The fused five- and six-membered rings in the title compound, C17H16ClN3O3S·0.5H2O, are practically coplanar, with the maximum deviation from the mean plane being 0.057 (3) Å for the C atom bound to the exocyclic N atom. The indazole system makes a dihedral angle of 66.18 (12)° with the plane through the benzene ring, and it is nearly perpendicular to the allyl group, as indicated by the N—N—C—C torsion angle of 79.2 (3)°. In the crystal, the water mol­ecule, lying on a twofold axis, forms O—H⋯N and accepts N—H⋯O hydrogen bonds. Additional C—H⋯O hydrogen bonds contribute to the formation of a chain along the b-axis direction. PMID:24109418

N-(2-Allyl-4-chloro-2H-indazol-5-yl)-4-meth-oxy-benzene-sulfonamide hemi-hydrate.

PubMed

Chicha, Hakima; Kouakou, Assoman; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

The fused five- and six-membered rings in the title compound, C17H16ClN3O3S·0.5H2O, are practically coplanar, with the maximum deviation from the mean plane being 0.057 (3) Å for the C atom bound to the exocyclic N atom. The indazole system makes a dihedral angle of 66.18 (12)° with the plane through the benzene ring, and it is nearly perpendicular to the allyl group, as indicated by the N-N-C-C torsion angle of 79.2 (3)°. In the crystal, the water mol-ecule, lying on a twofold axis, forms O-H⋯N and accepts N-H⋯O hydrogen bonds. Additional C-H⋯O hydrogen bonds contribute to the formation of a chain along the b-axis direction.

Origin of field-induced discontinuous phase transitions in N d2F e17

NASA Astrophysics Data System (ADS)

Diop, L. V. B.; Kuz'min, M. D.; Skokov, K. P.; Skourski, Y.; Gutfleisch, O.

2018-02-01

Magnetic properties of a trigonal ferromagnet N d2F e17 have been studied on single crystals in steady (14 T) and pulsed (32 T) magnetic fields. The easy-magnetization direction lies close to the [120] axis, deviating from the basal plane by 2 .9∘ (at T =5 K ). Of particular interest is the low-temperature magnetization process along the high-symmetry axis [001], which is the hard direction. This process is discontinuous and involves two first-order phase transitions (FOMPs). One of them (at 20 T) is a symmetry FOMP similar to that observed in S m2F e17 . The second transition (at 10.4 T) is unusual: as the magnetization turns abruptly toward the applied field, it also changes its azimuthal orientation (the angle φ ) by 60∘. Both transitions can be reasonably accounted for by the presence of a significant sixth-order trigonal anisotropy term.

Motor skills under varied gravitoinertial force in parabolic flight

NASA Astrophysics Data System (ADS)

Ross, Helen E.

Parabolic flight produces brief alternating periods of high and low gravitoinertial force. Subjects were tested on various paper-and-pencil aiming and tapping tasks during both normal and varied gravity in flight. It was found that changes in g level caused directional errors in the z body axis (the gravity axis), the arm aiming too high under 0g and too low under 2g. The standard deviation also increased for both vertical and lateral movements in the mid-frontal plane. Both variable and directional errors were greater under 0g than 2g. In an unpaced reciprocal tapping task subjects tended to increase their error rate rather than their movement time, but showed a non-significant trend towards slower speeds under 0g for all movement orientations. Larger variable errors or slower speeds were probably due to the difficulty of re-organising a motor skill in an unfamiliar force environment, combined with anchorage difficulties under 0g.

Self-calibration method of the inner lever-arm parameters for a tri-axis RINS

NASA Astrophysics Data System (ADS)

Song, Tianxiao; Li, Kui; Sui, Jie; Liu, Zengjun; Liu, Juncheng

2017-11-01

A rotational inertial navigation system (RINS) could improve navigation performance by modulating the inertial sensor errors with rotatable gimbals. When an inertial measurement unit (IMU) rotates, the deviations between the accelerometer-sensitive points and the IMU center will lead to an inner lever-arm effect. In this paper, a self-calibration method of the inner lever-arm parameters for a tri-axis RINS is proposed. A novel rotation scheme with variable angular rate rotation is designed to motivate the velocity errors caused by the inner lever-arm effect. By extending all inner lever-arm parameters as filter states, a Kalman filter with velocity errors as measurement is established to achieve the calibration. The accuracy and feasibility of the proposed method are illustrated by both simulations and experiments. The final results indicate that the inner lever-arm effect is significantly restrained after compensation by the calibration results.

Coherent Structures and Extreme Events in Rotating Multiphase Turbulent Flows

NASA Astrophysics Data System (ADS)

Biferale, L.; Bonaccorso, F.; Mazzitelli, I. M.; van Hinsberg, M. A. T.; Lanotte, A. S.; Musacchio, S.; Perlekar, P.; Toschi, F.

2016-10-01

By using direct numerical simulations (DNS) at unprecedented resolution, we study turbulence under rotation in the presence of simultaneous direct and inverse cascades. The accumulation of energy at large scale leads to the formation of vertical coherent regions with high vorticity oriented along the rotation axis. By seeding the flow with millions of inertial particles, we quantify—for the first time—the effects of those coherent vertical structures on the preferential concentration of light and heavy particles. Furthermore, we quantitatively show that extreme fluctuations, leading to deviations from a normal-distributed statistics, result from the entangled interaction of the vertical structures with the turbulent background. Finally, we present the first-ever measurement of the relative importance between Stokes drag, Coriolis force, and centripetal force along the trajectories of inertial particles. We discover that vortical coherent structures lead to unexpected diffusion properties for heavy and light particles in the directions parallel and perpendicular to the rotation axis.

State of the art in protection of erosion-corrosion on vertical axis tidal current turbine

NASA Astrophysics Data System (ADS)

Musabikha, Siti; Utama, I. Ketut Aria Pria; Mukhtasor

2018-05-01

Vertical axis tidal current turbine is main part of ocean energy devices which converts the tidal current energy into electricity. Its development is arising too due to increased interest research topic concerning climate change mitigation. Due to its rotating movement, it will be induced mechanical forces, such as shear stress and/or particle impact. Because of its natural operations, vertical axis turbine is also being exposed to harsh and corroding marine environment itself. In order to secure the vertical tidal turbine devices from mechanical wear and corrosion effects which is lead to a material loss, an appropriate erosion-corrosion protection needs to be defined. Its protection actionscan be derived such as design factors, material selections, inhibitors usage, cathodic protections, and coatings. This paper aims to analyze protection method which is necessary to control erosion-corrosion phenomenon that appears to the vertical axis tidal current turbine.

Wrist joint assembly

NASA Technical Reports Server (NTRS)

Kersten, L.; Johnson, J. D. (Inventor)

1978-01-01

A wrist joint assembly is provided for use with a mechanical manipulator arm for finely positioning an end-effector carried by the wrist joint on the terminal end of the manipulator arm. The wrist joint assembly is pivotable about a first axis to produce a yaw motion, a second axis is to produce a pitch motion, and a third axis to produce a roll motion. The wrist joint assembly includes a disk segment affixed to the terminal end of the manipulator arm and a first housing member, a second housing member, and a third housing member. The third housing member and the mechanical end-effector are moved in the yaw, pitch, and roll motion. Drive means are provided for rotating each of the housings about their respective axis which includes a cluster of miniature motors having spur gears carried on the output drive shaft which mesh with a center drive gear affixed on the housing to be rotated.

Intravertebral deformation in idiopathic scoliosis: a transverse plane computer tomographic study.

PubMed

Kotwicki, Tomasz; Napiontek, Marek

2008-03-01

The scoliotic vertebrae are submitted to (1) the displacement in the 3-dimensional space and (2) the bone remodeling, which results in a 3-dimensional intrinsic vertebral deformation. Both phenomena are most expressed inside the apical zone of the curve and can be measured in a computer tomographic (CT) scan. A comparative study of CT thoracic scans in scoliotic and normal children was performed to provide a better description of the altered anatomy with respect to patomechanism of scoliosis. Twenty-three scoliotic girls, aged 14.3 +/- 2.1 years, a case of a right thoracic curve with a Cobb angle of 60.6 +/- 19.3 degrees, and 24 controls, free of spinal deformity, sex- and age-matched, underwent CT examination of the thorax at the level of Th8 to Th9 vertebra. The rotation angle of the apical vertebra and the sagittal to coronal rib cage diameters ratio were measured. The intravertebral deformation was assessed by measuring the angles between the axis of the whole vertebra and the axes of the spinous or transverse processes. The ratio of sagittal to coronal chest diameter was reduced in scoliosis patients (P < 0.001) and correlated with the Cobb angle. The angle between the axis of vertebra and the spinous process increased (P = 0.008), and its value was positively correlated with the rotation angle of the vertebra (r = 0.78, P < 0.05); however, the rotation was oriented clockwise, whereas the spinous process deviation was counterclockwise. The angle between the spinous and the transverse process revealed greater values on the concave side (P < 0.001), whereas the transverse processes were not deviated from the axis of vertebra (P = 0.469). A constant pattern, previously not described, of the alteration of morphology of the apical vertebra due to the intravertebral bone remodeling was identified. The intravertebral deformation accompanied the displacement of the vertebra with a linear correlation; however, the 2 phenomena were developing in the opposite directions. Level III, cross-sectional study.

Diagnostic value of QRS and S wave variation in patients with suspicion of acute pulmonary embolism.

PubMed

Çağdaş, Metin; Karakoyun, Süleyman; Rencüzoğulları, İbrahim; Karabağ, Yavuz; Artaç, İnanç; İliş, Doğan; Hamideyin, Şerif; Karayol, Sibel; Çiftçi, Handan; Çınar, Tufan

2018-03-29

This study aimed to investigate the diagnostic value of QRS and S wave variation in patients admitted to the emergency department with suspicion of acute pulmonary embolism (APE). Computerized tomographic pulmonary angiography (CTPA) was performed in 118 consecutive patients to evaluate patients with suspected APE, and 106 subjects with appropriate electrocardiogram and CT images constituted the study population. Using CTPA, APE was diagnosed in 48.1% (n:51) of the study population. The comparison of patients with APE and those without APE revealed that increased heart rate, right axis deviation of QRS axis, complete or incomplete right bundle branch block, prominent S wave in lead D1, increased QRS duration, percentage of QRS (9,8[4,8-19,0] vs 3,8[2,7-71]; p<0,001), S wave variation (22,3[9,6-31,9] vs 4,8 [2-8]; p<0,001) and ΔS wave amplitude (1.1[0.5-1.5] vs 0.2[0.1-0.5]; p<0.001) were significantly associated with APE, but no relationship was detected with respect to the presence of atrial arrhythmias, clockwise rotation of the horizontal axis, fragmentation, ST segment deviation, T wave inversion, and S1Q3T3 and S1S2S3 patterns. The percentage of S wave variation (OR: 1072 per 1% increase, 95% CI:1011-1137) was found to be an independent predictor of APE. ΔS wave amplitude>0.5mm predicted APE with a sensitivity of 72.6% and a specificity of 74.6% (AUC:0.805, 95% CI: 0.717-0.876; p<0.001). The present study demonstrated that QRS and S wave variation could be useful electrocardiographic signs for the diagnosis of APE. Copyright © 2018. Published by Elsevier Inc.

Clinical and Financial Impact of Ordering an Echocardiogram in Children with Left Axis Deviation on Their Electrocardiogram.

PubMed

Ravi, Prasad; Ashwath, Ravi; Strainic, James; Li, Hong; Steinberg, Jon; Snyder, Christopher

2016-01-01

Left axis deviation (LAD) on the electrocardiogram (ECG) is associated with congenital heart disease (CHD), prompting the clinician to order further testing when evaluating a patient with this finding. The purpose is to (1) compare the physical examination (PE) by a pediatric cardiologist to echocardiogram (ECHO) findings in patients with LAD on resting ECG and (2) assess cost of performing ECHO on all patients with LAD on ECG. An IRB approved, retrospective cohort study was performed on patients with LAD (QRS axis ≥0° to -90°) on ECG between 01/02 and 12/12. age >0.25 and <18 years, non-postoperative, and PE and ECHO by pediatric cardiologist. A decision tree model analyzed cost of ECHO in patients with LAD and normal/abnormal PE. Cost of complete ECHO ($239.00) was obtained from 2014 Medicare reimbursement rates. A total of 146 patients met inclusion criteria with 46.5% (68) having normal PE and ECHO, 1.4% (2) having normal PE and abnormal ECHO, 47.3% (69) having abnormal PE and ECHO, and 4.8% (7) having an abnormal PE and normal ECHO. Sensitivity and specificity of PE for detecting abnormalities in this population was 97% and 90%. Positive and negative predictive value of PE was 91% and 97.5%. In patients with normal PE, the cost to identify an ECHO abnormality was $8365, and $263 for those with abnormal PE. In presence of LAD on ECG, the sensitivity, specificity, and positive and negative predictive values of PE by a pediatric cardiologist are excellent at identifying CHD. Performing an ECHO on patients with LAD on ECG is only cost effective in the presence of an abnormal PE. In the presence of normal PE, there is a possibility of missing incidental structural cardiac disease in approximately 2% if an ECHO is not performed. © 2015 Wiley Periodicals, Inc.

A model of curved saccade trajectories: spike rate adaptation in the brainstem as the cause of deviation away.

PubMed

Kruijne, Wouter; Van der Stigchel, Stefan; Meeter, Martijn

2014-03-01

The trajectory of saccades to a target is often affected whenever there is a distractor in the visual field. Distractors can cause a saccade to deviate towards their location or away from it. The oculomotor mechanisms that produce deviation towards distractors have been thoroughly explored in behavioral, neurophysiological and computational studies. The mechanisms underlying deviation away, on the other hand, remain unclear. Behavioral findings suggest a mechanism of spatially focused, top-down inhibition in a saccade map, and deviation away has become a tool to investigate such inhibition. However, this inhibition hypothesis has little neuroanatomical or neurophysiological support, and recent findings go against it. Here, we propose that deviation away results from an unbalanced saccade drive from the brainstem, caused by spike rate adaptation in brainstem long-lead burst neurons. Adaptation to stimulation in the direction of the distractor results in an unbalanced drive away from it. An existing model of the saccade system was extended with this theory. The resulting model simulates a wide range of findings on saccade trajectories, including findings that have classically been interpreted to support inhibition views. Furthermore, the model replicated the effect of saccade latency on deviation away, but predicted this effect would be absent with large (400 ms) distractor-target onset asynchrony. This prediction was confirmed in an experiment, which demonstrates that the theory both explains classical findings on saccade trajectories and predicts new findings. Copyright © 2014 Elsevier Inc. All rights reserved.

Structural Inheritance of the Actin Cytoskeletal Organization Determines the Body Axis in Regenerating Hydra.

PubMed

Livshits, Anton; Shani-Zerbib, Lital; Maroudas-Sacks, Yonit; Braun, Erez; Keren, Kinneret

2017-02-07

Understanding how mechanics complement bio-signaling in defining patterns during morphogenesis is an outstanding challenge. Here, we utilize the multicellular polyp Hydra to investigate the role of the actomyosin cytoskeleton in morphogenesis. We find that the supra-cellular actin fiber organization is inherited from the parent Hydra and determines the body axis in regenerating tissue segments. This form of structural inheritance is non-trivial because of the tissue folding and dynamic actin reorganization involved. We further show that the emergence of multiple body axes can be traced to discrepancies in actin fiber alignment at early stages of the regeneration process. Mechanical constraints induced by anchoring regenerating Hydra on stiff wires suppressed the emergence of multiple body axes, highlighting the importance of mechanical feedbacks in defining and stabilizing the body axis. Together, these results constitute an important step toward the development of an integrated view of morphogenesis that incorporates mechanics. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Postreceptoral chromatic-adaptation mechanisms in the red-green and blue-yellow systems using simple reaction times

NASA Astrophysics Data System (ADS)

Medina, José M.; Díaz, José A.

2006-05-01

Simple visual-reaction times (VRT) were measured for a variety of stimuli selected along red-green (L-M axis) and blue-yellow [S-(L+M) axis] directions in the isoluminant plane under different adaptation stimuli. Data were plotted in terms of the RMS cone contrast in contrast-threshold units. For each opponent system, a modified Piéron function was fitted in each experimental configuration and on all adaptation stimuli. A single function did not account for all the data, confirming the existence of separate postreceptoral adaptation mechanisms in each opponent system under suprathreshold conditions. The analysis of the VRT-hazard functions suggested that both color-opponent mechanisms present a well-defined, transient-sustained structure at marked suprathreshold conditions. The influence of signal polarity and chromatic adaptation on each color axis proves the existence of asymmetries in the integrated hazard functions, suggesting separate detection mechanisms for each pole (red, green, blue, and yellow detectors).

Intraoperative positioning of the hindfoot with the hindfoot alignment guide: a pilot study.

PubMed

Frigg, Arno; Jud, Lukas; Valderrabano, Victor

2014-01-01

In a previous study, intraoperative positioning of the hindfoot by visual means resulted in the wrong varus/valgus position by 8 degrees and a relatively large standard deviation of 8 degrees. Thus, new intraoperative means are needed to improve the precision of hindfoot surgery. We therefore sought a hindfoot alignment guide that would be as simple as the alignment guides used in total knee arthroplasty. A novel hindfoot alignment guide (HA guide) has been developed that projects the mechanical axis from the tibia down to the heel. The HA guide enables the positioning of the hindfoot in the desired varus/valgus position and in plantigrade position in the lateral plane. The HA guide was used intraoperatively from May through November 2011 in 11 complex patients with simultaneous correction of the supramalleolar, tibiotalar, and inframalleolar alignment. Pre- and postoperative Saltzman views were taken and the position was measured. The HA guide significantly improved the intraoperative positioning compared with visual means: The accuracy with the HA guide was 4.5 ± 5.1 degrees (mean ± standard deviation) and without the HA guide 9.4 ± 5.5 degrees (P < .05). In 7 of 11 patients, the preoperative plan was changed because of the HA guide (2 avoided osteotomies, 5 additional osteotomies). The HA guide helped to position the hindfoot intraoperatively with greater precision than visual means. The HA guide was especially useful for multilevel corrections in which the need for and the amount of a simultaneous osteotomy had to be evaluated intraoperatively. Level IV, case series.

Improved accuracy of alignment with patient-specific positioning guides compared with manual instrumentation in TKA.

PubMed

Ng, Vincent Y; DeClaire, Jeffrey H; Berend, Keith R; Gulick, Bethany C; Lombardi, Adolph V

2012-01-01

Coronal malalignment occurs frequently in TKA and may affect implant durability and knee function. Designed to improve alignment accuracy and precision, the patient-specific positioning guide is predicated on restoration of the overall mechanical axis and is a multifaceted new tool in achieving traditional goals of TKA. We compared the effectiveness of patient-specific positioning guides to manual instrumentation with intramedullary femoral and extramedullary tibial guides in restoring the mechanical axis of the extremity and achieving neutral coronal alignment of the femoral and tibial components. We retrospectively reviewed 569 TKAs performed with patient-specific positioning guides and 155 with manual instrumentation by two surgeons using postoperative long-leg radiographs. For all patients, we assessed the zone in which the overall mechanical axis passed through the knee, and for one surgeon's cases (105 patient-specific positioning guide, 55 manual instrumentation), we also measured the hip-knee-ankle angle and the individual component angles with respect to their mechanical axes. The overall mechanical axis passed through the central third of the knee more often with patient-specific positioning guides (88%) than with manual instrumentation (78%). The overall mean hip-knee-ankle angle for patient-specific positioning guides (180.6°) was similar to manual instrumentation (181.1°), but there were fewer ± 3° hip-knee-ankle angle outliers with patient-specific positioning guides (9%) than with manual instrumentation (22%). The overall mean tibial (89.9° versus 90.4°) and femoral (90.7° versus 91.3°) component angles were closer to neutral with patient-specific positioning guides than with manual instrumentation, but the rate of ± 2° outliers was similar for both the tibia (10% versus 7%) and femur (22% versus 18%). Patient-specific positioning guides can assist in achieving a neutral mechanical axis with reduction in outliers.

Field trial of a diagnostic axis for defense mechanisms for DSM-IV.

PubMed

Perry, J C; Hoglend, P; Shear, K; Vaillant, G E; Horowitz, M; Kardos, M E; Bille, H; Kagan, D

1998-01-01

Following critiques that the DSM multiaxial system lacks psychodynamic information useful for treatment, an axis for defense mechanisms was developed for DSM-IV, including up to 7 individual defenses from a glossary of 27, and 3 predominant defense levels from a list of 7. We tested the feasibility, reliability, and discriminability of the proposed axis. Clinician and psychiatric resident volunteers were trained at two U.S. and one Norwegian sites. After conducting initial interviews on 107 patients, they rated the DSM-III-R and defense axes, as did a second blind rater. Median kappa reliabilities were .42 (individual defenses), and .47 (defense levels). A summary measure, Overall Defensive Functioning (ODF), had similar reliability to current GAF (IR .68 vs. .62), similar 1-month stability (.75 vs. .78), but greater 6-month stability (.51 vs. .17). Independent of Axis III, ODF had small to moderate associations with other Axes and symptoms. Our findings indicate that the defense axis is a feasible, acceptably reliable, and nonredundant addition to DSM-IV, which may prove useful for planning and conducting treatment.

Brain angiotensin-(1-7)/Mas axis: A new target to reduce the cardiovascular risk to emotional stress.

PubMed

Fontes, Marco Antônio Peliky; Martins Lima, Augusto; Santos, Robson Augusto Souza dos

2016-04-01

Emotional stress is now considered a risk factor for several diseases including cardiac arrhythmias and hypertension. It is well known that the activation of neuroendocrine and autonomic mechanisms features the response to emotional stress. However, its link to cardiovascular diseases and the regulatory mechanisms involved remain to be further comprehended. The renin-angiotensin system (RAS) plays an important role in homeostasis on all body systems. Specifically in the brain, the RAS regulates a number of physiological aspects. Recent data indicate that the activation of angiotensin-converting enzyme/angiotensin II/AT1 receptor axis facilitates the emotional stress responses. On the other hand, growing evidence indicates that its counterregulatory axis, the angiotensin-converting enzyme 2 (ACE2)/(Ang)iotensin-(1-7)/Mas axis, reduces anxiety and attenuates the physiological responses to emotional stress. The present review focuses on angiotensin-(1-7)/Mas axis as a promising target to attenuate the physiological response to emotional stress reducing the risk of cardiovascular diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nonlinear Deformation Behavior of New Braided Composites with Six-axis Yarn Orientations

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

Ahn, H.-C.; Yu, W.-R.; Guo, Z.

The braiding technology is one of fabrication methods that can produce three-dimensional fiber preforms. Braided composites have many advantages over other two-dimensional composites such as no delamination, high impact and fatigue properties, near-net shape preform, etc. Due to the undulated yarns in the braided preforms, however, their axial stiffness is lower than that of uni-directional or woven composites. To improve the axial stiffness, the longitudinal axial yarns were already introduced along with the braiding axis (five-axis braiding technology). In this study, we developed a new braided structure using six-axis braiding technology. In addition to braiding and longitudinal axial yarns, transversemore » axial yarn was introduced. New braided composites, so called six-axis braiding composites, were manufactured using ultra high molecular weight polyethylene and epoxy resin and their mechanical properties were characterized. To investigate the mechanical performance of these braided composites according to their manufacturing conditions, a numerical analysis was performed using their unit-cell modeling and finite element analysis. In the analysis the nonlinear deformation behavior will be included.« less

Validation of a new method for finding the rotational axes of the knee using both marker-based roentgen stereophotogrammetric analysis and 3D video-based motion analysis for kinematic measurements.

PubMed

Roland, Michelle; Hull, M L; Howell, S M

2011-05-01

In a previous paper, we reported the virtual axis finder, which is a new method for finding the rotational axes of the knee. The virtual axis finder was validated through simulations that were subject to limitations. Hence, the objective of the present study was to perform a mechanical validation with two measurement modalities: 3D video-based motion analysis and marker-based roentgen stereophotogrammetric analysis (RSA). A two rotational axis mechanism was developed, which simulated internal-external (or longitudinal) and flexion-extension (FE) rotations. The actual axes of rotation were known with respect to motion analysis and RSA markers within ± 0.0006 deg and ± 0.036 mm and ± 0.0001 deg and ± 0.016 mm, respectively. The orientation and position root mean squared errors for identifying the longitudinal rotation (LR) and FE axes with video-based motion analysis (0.26 deg, 0.28 m, 0.36 deg, and 0.25 mm, respectively) were smaller than with RSA (1.04 deg, 0.84 mm, 0.82 deg, and 0.32 mm, respectively). The random error or precision in the orientation and position was significantly better (p=0.01 and p=0.02, respectively) in identifying the LR axis with video-based motion analysis (0.23 deg and 0.24 mm) than with RSA (0.95 deg and 0.76 mm). There was no significant difference in the bias errors between measurement modalities. In comparing the mechanical validations to virtual validations, the virtual validations produced comparable errors to those of the mechanical validation. The only significant difference between the errors of the mechanical and virtual validations was the precision in the position of the LR axis while simulating video-based motion analysis (0.24 mm and 0.78 mm, p=0.019). These results indicate that video-based motion analysis with the equipment used in this study is the superior measurement modality for use with the virtual axis finder but both measurement modalities produce satisfactory results. The lack of significant differences between validation techniques suggests that the virtual sensitivity analysis previously performed was appropriately modeled. Thus, the virtual axis finder can be applied with a thorough understanding of its errors in a variety of test conditions.

76 FR 28645 - Drawbridge Operation Regulation; Calcasieu River, Westlake, LA

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-18

... deviation from the regulation governing the operation of the Union Pacific Railroad swing bridge across the... the electrical and mechanical systems of the bridge. This deviation allows the bridge to remain closed.... SUPPLEMENTARY INFORMATION: The Union Pacific Railroad has requested a temporary deviation from the operating...

Elastin governs the mechanical response of medial collateral ligament under shear and transverse tensile loading.

PubMed

Henninger, Heath B; Valdez, William R; Scott, Sara A; Weiss, Jeffrey A

2015-10-01

Elastin is a highly extensible structural protein network that provides near-elastic resistance to deformation in biological tissues. In ligament, elastin is localized between and along the collagen fibers and fascicles. When ligament is stretched along the primary collagen axis, elastin supports a relatively high percentage of load. We hypothesized that elastin may also provide significant load support under elongation transverse to the primary collagen axis and shear along the collagen axis. Quasi-static transverse tensile and shear material tests were performed to quantify the mechanical contributions of elastin during deformation of porcine medial collateral ligament. Dose response studies were conducted to determine the level of elastase enzymatic degradation required to produce a maximal change in the mechanical response. Maximal changes in peak stress occurred after 3h of treatment with 2U/ml porcine pancreatic elastase. Elastin degradation resulted in a 60-70% reduction in peak stress and a 2-3× reduction in modulus for both test protocols. These results demonstrate that elastin provides significant resistance to elongation transverse to the collagen axis and shear along the collagen axis while only constituting 4% of the tissue dry weight. The magnitudes of the elastin contribution to peak transverse and shear stress were approximately 0.03 MPa, as compared to 2 MPa for axial tensile tests, suggesting that elastin provides a highly anisotropic contribution to the mechanical response of ligament and is the dominant structural protein resisting transverse and shear deformation of the tissue. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Noninvasive assessment of myocardial mechanics of the left ventricle in rabbits using velocity vector imaging.

PubMed

Zhou, Jia; Pu, Da-Rong; Tian, Lei-Qi; Tong, Hai; Liu, Hong-Yu; Tang, Yan; Zhou, Qi-Chang

2015-05-28

Our study aimed to investigate the feasibility of velocity vector imaging (VVI) to analyze left ventricular (LV) myocardial mechanics in rabbits at basal state. The animals used in this study were 30 New Zealand white rabbits. All rabbits underwent routine echocardiography under VVI-mode at basal state. The 2-dimensional (2-D) echocardiography images acquired included parasternal left long-axis views and short-axis views at the level of LV mitral valve, papillary muscles, and apex. Images were analyzed by VVI software. At basal state, longitudinal LV velocity decreased from the basal to the apical segment (P<0.05). In the short axis direction, the highest peak myocardial velocity was found between the anterior septum and anterior wall for each segment at the same level; the peak strains and strain rates (SR) were the highest in the anterior and lateral wall compared to other segments (all P<0.05). During systole, LV base rotated in a clockwise direction and LV apex rotated in a counter-clockwise direction, while during diastole, both LV base and apex rotated in the direction opposite to systole. The rotation angle, rotation velocity and unwinding velocity in the apical segment were greater than the basal segment (P<0.05). VVI is a reliable tool for evaluating LV myocardial mechanics in rabbits at basal state, and the LV long-axis short-axis and torsional motions reflect the normal regular patterns. Our study lays the foundation for future experimental approaches in rabbit models and for other applications related to the study of human myocardial mechanics.

Characteristics of a KA-band third-harmonic peniotron driven by a high-quality linear axis-encircling electron beam

NASA Astrophysics Data System (ADS)

Zhao, Xiaoyun; Tuo, Xianguo; Ge, Qing; Peng, Ying

2017-12-01

We employ a high-quality linear axis-encircling electron beam generated by a Cuccia coupler to drive a Ka-band third-harmonic peniotron and develop a self-consistent nonlinear calculation code to numerically analyze the characteristics of the designed peniotron. It is demonstrated that through a Cuccia coupler, a 6 kV, 0.5 A pencil beam and an input microwave power of 16 kW at 10 GHz can generate a 37 kV, 0.5 A linear axis-encircling beam, and it is characterized by a very low velocity spread. Moreover, the electron beam guiding center deviation can be adjusted easily. Driven by such a beam, a 30 GHz, Ka-band third-harmonic peniotron is predicted to achieve a conversion efficiency of 51.0% and a microwave output power of 9.44 kW; the results are in good agreement with the Magic3D simulation. Using this code, we studied the factors influencing the peniotron performance, and it can provide some guidelines for the design of a Ka-band third-harmonic peniotron driven by a linear electron beam and can promote the application of high-harmonic peniotrons in practice.

In-plane magnetic anisotropy in strontium iridate S r2Ir O4

NASA Astrophysics Data System (ADS)

Nauman, Muhammad; Hong, Yunjeong; Hussain, Tayyaba; Seo, M. S.; Park, S. Y.; Lee, N.; Choi, Y. J.; Kang, Woun; Jo, Younjung

2017-10-01

Magnetic anisotropy in strontium iridate (S r2Ir O4 ) is found to be large because of the strong spin-orbit interactions. In our work, we studied the in-plane magnetic anisotropy of S r2Ir O4 and traced the anisotropic exchange interactions between the isospins in the crystal. The magnetic-field-dependent torque τ(H ) showed a prominent transition from the canted antiferromagnetic state to the weak ferromagnetic (WFM) state. A comprehensive analysis was conducted to examine the isotropic and anisotropic regimes and probe the easy magnetization axis along the a b plane. The angle-dependent torque τ(θ) revealed a deviation from the sinusoidal behavior, and small differences in hysteresis were observed around 0° and 90° in the low-magnetic-field regime. This indicates that the orientation of the easy axis of the FM component is along the b axis, where the antiferromagnetic to WFM spin-flop transition occurs. We compared the coefficients of the magnetic susceptibility tensors and captured the anisotropy of the material. The in-plane τ(θ) revealed a tendency toward isotropic behavior for fields with values above the field value of the WFM transition.

Atmospheric density determination using high-accuracy satellite GPS data

NASA Astrophysics Data System (ADS)

Tingling, R.; Miao, J.; Liu, S.

2017-12-01

Atmospheric drag is the main error source in the orbit determination and prediction of low Earth orbit (LEO) satellites, however, empirical models which are used to account for atmosphere often exhibit density errors around 15 30%. Atmospheric density determination thus become an important topic for atmospheric researchers. Based on the relation between atmospheric drag force and the decay of orbit semi-major axis, we derived atmospheric density along the trajectory of CHAMP with its Rapid Science Orbit (RSO) data. Three primary parameters are calculated, including the ratio of cross sectional area to mass, drag coefficient, and the decay of semi-major axis caused by atmospheric drag. We also analyzed the source of error and made a comparison between GPS-derived and reference density. Result on 2 Dec 2008 shows that the mean error of GPS-derived density can decrease from 29.21% to 9.20% when time span adopted on the process of computation increase from 10min to 50min. Result for the whole December indicates that when the time span meet the condition that the amplitude of the decay of semi-major axis is much greater than its standard deviation, then density precision of 10% can be achieved.

An automatic calibration procedure for remote eye-gaze tracking systems.

PubMed

Model, Dmitri; Guestrin, Elias D; Eizenman, Moshe

2009-01-01

Remote gaze estimation systems use calibration procedures to estimate subject-specific parameters that are needed for the calculation of the point-of-gaze. In these procedures, subjects are required to fixate on a specific point or points at specific time instances. Advanced remote gaze estimation systems can estimate the optical axis of the eye without any personal calibration procedure, but use a single calibration point to estimate the angle between the optical axis and the visual axis (line-of-sight). This paper presents a novel automatic calibration procedure that does not require active user participation. To estimate the angles between the optical and visual axes of each eye, this procedure minimizes the distance between the intersections of the visual axes of the left and right eyes with the surface of a display while subjects look naturally at the display (e.g., watching a video clip). Simulation results demonstrate that the performance of the algorithm improves as the range of viewing angles increases. For a subject sitting 75 cm in front of an 80 cm x 60 cm display (40" TV) the standard deviation of the error in the estimation of the angles between the optical and visual axes is 0.5 degrees.

Dynamic characteristics of triaxial active control magnetic bearing with asymmetric structure

NASA Astrophysics Data System (ADS)

Nakajima, Atsushi; Hirata, Katsuhiro; Niguchi, Noboru; Kato, Masayuki

2018-03-01

Supporting forces of magnetic bearings are lower than those of mechanical bearings. In order to solve these problems, this paper proposes a new three-axis active control magnetic bearing (3-axis AMB) with an asymmetric structure where its rotor is attracted only in one axial direction due to a negative pressure of fluid. Our proposed 3-axis AMB can generate a large suspension force in one axial direction due to the asymmetric structure. The performances of our proposed 3-axis AMB are computed through 3-D finite element analysis.

Fit of cobalt–chromium implant frameworks before and after ceramic veneering in comparison with CNC‐milled titanium frameworks

PubMed Central

Svanborg, Per; Eliasson, Alf

2015-01-01

Abstract Computer‐aided design/computer‐aided manufacturing fabrication of implant‐supported frameworks is a standard procedure, and the use of ceramic‐veneered cobalt–chromium alloys is increasing. However, no data are available concerning the precision of fit of these frameworks and the impact on the fit of the veneering procedure. The aim of this study was to evaluate the fit of computer numeric‐controlled‐milled cobalt–chromium and titanium implant frameworks for edentulous maxillas, provided with six implants. An additional aim was to evaluate the effect of ceramic veneering on the fit of the cobalt–chromium frameworks. Ten stone casts simulating an edentulous maxilla provided with six dental implants and abutments were produced. One computer numeric‐controlled‐milled cobalt–chromium framework and one titanium framework were fabricated for each stone cast. Each stone cast and corresponding titanium and cobalt–chromium framework was measured with a coordinate measuring machine in the three‐dimensional (X axis, Y axis, and Z axis) directions. Both milled titanium and cobalt–chromium frameworks presented a good fit in the vertical plane (Z axis), 5.3 µm for titanium frameworks and 4.6 µm for the cobalt–chromium frameworks. The titanium frameworks showed a statistically significant smaller mean degree of misfit in the horizontal plane, X (5.0 µm) and Y (2.8 µm) axes as compared with the cobalt–chromium frameworks presenting a mean deviation of 13.5 µm in X axis and 6.3 µm in Y axis (P < 0.001). After ceramic veneering of the cobalt–chromium frameworks, the horizontal distortion significantly decreased from 13.5 to 9.7 µm in X axis (P = 0.007) and from 6.3 to 4.4 µm in Y axis (P = 0.017). The fit of both titanium and cobalt–chromium frameworks was very good. There were small but significant differences in fit between the titanium and cobalt–chromium frameworks, but the difference is of no clinical significance. The ceramic veneering resulted in a minor but significant improvement of the fit for the cobalt–chromium frameworks. PMID:29744140

T-wave axis deviation and left ventricular hypertrophy interaction in diabetes and hypertension.

PubMed

Assanelli, Deodato; Di Castelnuovo, Augusto; Rago, Livia; Badilini, Fabio; Vinetti, Giovanni; Gianfagna, Francesco; Salvetti, Massimo; Zito, Francesco; Donati, Maria Benedetta; de Gaetano, Giovanni; Iacoviello, Licia

2013-01-01

Electrocardiographic signs of left ventricular hypertrophy (ECG-LVH) and T-wave axis (TA) deviation are independent predictors of fatal and non fatal events. We assessed the prevalence of ECG-LVH, TA abnormalities and their combination according to the presence or absence of diabetes and/or hypertension in a large sample of the adult general Italian population. Data from 10,184 women (54 ± 11 years) and 8775 men (54 ± 11 years) were analyzed from the Moli-sani cohort, a database of randomly recruited adults (age >35) from the general population of Molise, a central region of Italy that includes collection of standard 12-lead resting ECG. Subjects with previous myocardial infarction, angina, cerebrovascular disease or left bundle brunch block or missing values for TA or ECG-LVH have been excluded. TA was measured from the standard 12-lead ECG and it was defined as the rotation of the T wave in the frontal plane as computed by a proprietary algorithm (CalECG/Bravo, AMPS-LLC, NY). ECG-LVH was defined as Sokolow Lyon voltage (SLv) >35 mm or Cornell voltage duration Product (CP) >= 2440 mm*ms. Among subjects with ECG-LVH, prevalence of hypertension was 59.0% and 49.7%, respectively for men and women, whereas that of diabetes was 10.7% and 5.7%. In hypertensives, TA was normal in 72.3% of subjects, borderline in 24.8% and abnormal in 2.9%. In diabetics, TA was normal in 70.4% of subjects, borderline in 26.5% and abnormal in 3.1%. In both hypertensive and diabetic subjects, the prevalence of ECG-LVH, was significantly greater in subjects with borderline or abnormal TA. Hypertension was an independent predictor of abnormal TA (odd ratio: 1.38, P = .025). These results suggest that hypertension might play a relevant role in the pathogenesis of TA deviation. © 2013.

8-Fluoro-4-oxo-4H-chromene-3-carbalde­hyde

PubMed Central

Ishikawa, Yoshinobu

2014-01-01

In the title compound, C10H5FO3, the non-H atoms of the 8-fluoro­chromone unit are essentially coplanar (r.m.s. deviation = 0.0259 Å), with a largest deviation from the mean plane of 0.0660 (12) Å for the chromone carbonyl O atom. The formyl group is twisted with respect to the attached ring [C—C—C—O torsion angles = −11.00 (19) and 170.81 (11)°]. In the crystal, mol­ecules are linked via weak C—H⋯O hydrogen bonds along the a axis and [-101], forming corrugated layers parallel to (010). In addition, π–π stacking inter­actions [centroid–centroid distance between the planes of the pyran and benzene rings = 3.519 (2) Å] are observed between these layers. PMID:25161562

Validation of a partial coherence interferometry method for estimating retinal shape

PubMed Central

Verkicharla, Pavan K.; Suheimat, Marwan; Pope, James M.; Sepehrband, Farshid; Mathur, Ankit; Schmid, Katrina L.; Atchison, David A.

2015-01-01

To validate a simple partial coherence interferometry (PCI) based retinal shape method, estimates of retinal shape were determined in 60 young adults using off-axis PCI, with three stages of modeling using variants of the Le Grand model eye, and magnetic resonance imaging (MRI). Stage 1 and 2 involved a basic model eye without and with surface ray deviation, respectively and Stage 3 used model with individual ocular biometry and ray deviation at surfaces. Considering the theoretical uncertainty of MRI (12-14%), the results of the study indicate good agreement between MRI and all three stages of PCI modeling with <4% and <7% differences in retinal shapes along horizontal and vertical meridians, respectively. Stage 2 and Stage 3 gave slightly different retinal co-ordinates than Stage 1 and we recommend the intermediate Stage 2 as providing a simple and valid method of determining retinal shape from PCI data. PMID:26417496

Validation of a partial coherence interferometry method for estimating retinal shape.

PubMed

Verkicharla, Pavan K; Suheimat, Marwan; Pope, James M; Sepehrband, Farshid; Mathur, Ankit; Schmid, Katrina L; Atchison, David A

2015-09-01

To validate a simple partial coherence interferometry (PCI) based retinal shape method, estimates of retinal shape were determined in 60 young adults using off-axis PCI, with three stages of modeling using variants of the Le Grand model eye, and magnetic resonance imaging (MRI). Stage 1 and 2 involved a basic model eye without and with surface ray deviation, respectively and Stage 3 used model with individual ocular biometry and ray deviation at surfaces. Considering the theoretical uncertainty of MRI (12-14%), the results of the study indicate good agreement between MRI and all three stages of PCI modeling with <4% and <7% differences in retinal shapes along horizontal and vertical meridians, respectively. Stage 2 and Stage 3 gave slightly different retinal co-ordinates than Stage 1 and we recommend the intermediate Stage 2 as providing a simple and valid method of determining retinal shape from PCI data.

A new method for the identification of non-Gaussian line profiles in elliptical galaxies

NASA Technical Reports Server (NTRS)

Van Der Marel, Roeland P.; Franx, Marijn

1993-01-01

A new parameterization for the line profiles of elliptical galaxies, the Gauss-Hermite series, is proposed. This approach expands the line profile as a sum of orthogonal functions which minimizes the correlations between the errors in the parameters of the fit. This method also make use of the fact that Gaussians provide good low-order fits to observed line profiles. The method yields measurements of the line strength, mean radial velocity, and the velocity dispersion as well as two extra parameters, h3 and h4, that measure asymmetric and symmetric deviations of the line profiles from a Gaussian, respectively. The new method was used to derive profiles for three elliptical galaxies which all have asymmetric line profiles on the major axis with symmetric deviations from a Gaussian. Results confirm that elliptical galaxies have complex structures due to their complex formation history.

Evolution of Axis Specification Mechanisms in Jawed Vertebrates: Insights from a Chondrichthyan

PubMed Central

Coolen, Marion; Sauka-Spengler, Tatjana; Nicolle, Delphine; Le-Mentec, Chantal; Lallemand, Yvan; Silva, Corinne Da; Plouhinec, Jean-Louis; Robert, Benoît; Wincker, Patrick; Shi, De-Li; Mazan, Sylvie

2007-01-01

The genetic mechanisms that control the establishment of early polarities and their link with embryonic axis specification and patterning seem to substantially diverge across vertebrates. In amphibians and teleosts, the establishment of an early dorso-ventral polarity determines both the site of axis formation and its rostro-caudal orientation. In contrast, amniotes retain a considerable plasticity for their site of axis formation until blastula stages and rely on signals secreted by extraembryonic tissues, which have no clear equivalents in the former, for the establishment of their rostro-caudal pattern. The rationale for these differences remains unknown. Through detailed expression analyses of key development genes in a chondrichthyan, the dogfish Scyliorhinus canicula, we have reconstructed the ancestral pattern of axis specification in jawed vertebrates. We show that the dogfish displays compelling similarities with amniotes at blastula and early gastrula stages, including the presence of clear homologs of the hypoblast and extraembryonic ectoderm. In the ancestral state, these territories are specified at opposite poles of an early axis of bilateral symmetry, homologous to the dorso-ventral axis of amphibians or teleosts, and aligned with the later forming embryonic axis, from head to tail. Comparisons with amniotes suggest that a dorsal expansion of extraembryonic ectoderm, resulting in an apparently radial symmetry at late blastula stages, has taken place in their lineage. The synthesis of these results with those of functional analyses in model organisms supports an evolutionary link between the dorso-ventral polarity of amphibians and teleosts and the embryonic-extraembryonic organisation of amniotes. It leads to a general model of axis specification in gnathostomes, which provides a comparative framework for a reassessment of conservations both among vertebrates and with more distant metazoans. PMID:17440610

Solid medium thermal engine

NASA Technical Reports Server (NTRS)

Jedlicka, J. R.; Guist, L. R.; Beam, R. M. (Inventor)

1974-01-01

A device is described which uses a single phase metallic working substance to convert thermal energy directly into mechanical energy. The device consists of a cylindrical metal tube which is free to rotate about its axis while being subjected to continuous bending moment stresses along the longitudinal axis of rotation. The stressing causes portions of the tube to be under compression while other parts are under tension which in turn causes the tube to rotate and provide mechanical energy.

Aberration Theory and Design Techniques for Refracting Prism Systems.

NASA Astrophysics Data System (ADS)

Al-Bizri, N.

Available from UMI in association with The British Library. The general case of image formation by optical systems consisting of combinations of ordinary lens components and refracting prisms is studied in detail. Formulae for the sagittal and tangential magnifications, the pupil scale ratios, the image tilt, the positions of (newly defined) principal planes and the equivalent focal lengths have been derived. Formulae for the axial astigmatism, axial transverse chromatic aberration and the focal shift measure of the aberration due to the tilt of the image plane have also been obtained. All of these formulae are equally valid for any optical system which has a single plane of symmetry. The calculation of the wavefront aberration coefficients and of the variance of the aberration for such systems has been treated using the pre-inverted matrix method. In addition formulae for the numerical evaluation of the optical transfer function, the point spread function, the line spread function and the edge response function, have been obtained and programmed. First-order formulae, and a refinement technique, for the design of cemented refracting doublet prisms have been obtained, which ensure that the desired prismatic deviation of the axis is obtained, and that the axial astigmatism and the axial transverse chromatic aberration have stipulated target values. All of the above formulae have been carefully tested by numerical examples, and the design technique has been used to design endoscope objectives which provide small deviations (<10^circ ) of the optical axis.

Grasp and index finger reach zone during one-handed smartphone rear interaction: effects of task type, phone width and hand length.

PubMed

Lee, Songil; Kyung, Gyouhyung; Lee, Jungyong; Moon, Seung Ki; Park, Kyoung Jong

2016-11-01

Recently, some smartphones have introduced index finger interaction functions on the rear surface. The current study investigated the effects of task type, phone width, and hand length on grasp, index finger reach zone, discomfort, and muscle activation during such interaction. We considered five interaction tasks (neutral, comfortable, maximum, vertical, and horizontal strokes), two device widths (60 and 90 mm) and three hand lengths. Horizontal (vertical) strokes deviated from the horizontal axis in the range from -10.8° to -13.5° (81.6-88.4°). Maximum strokes appeared to be excessive as these caused 43.8% greater discomfort than did neutral strokes. The 90-mm width also appeared to be excessive as it resulted in 12.3% increased discomfort relative to the 60-mm width. The small-hand group reported 11.9-18.2% higher discomfort ratings, and the percent maximum voluntary exertion of their flexor digitorum superficialis muscle, pertaining to index finger flexion, was also 6.4% higher. These findings should be considered to make smartphone rear interaction more comfortable. Practitioner Summary: Among neutral, comfortable, maximum, horizontal, and vertical index finger strokes on smartphone rear surfaces, maximum vs. neutral strokes caused 43.8% greater discomfort. Horizontal (vertical) strokes deviated from the horizontal (vertical) axis. Discomfort increased by 12.3% with 90-mm- vs. 60-mm-wide devices. Rear interaction regions of five commercialised smartphones should be lowered 20 to 30 mm for more comfortable rear interaction.

Hypothalamic-Pituitary-Adrenal Hypofunction in Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS) as a Consequence of Activated Immune-Inflammatory and Oxidative and Nitrosative Pathways.

PubMed

Morris, Gerwyn; Anderson, George; Maes, Michael

2017-11-01

There is evidence that immune-inflammatory and oxidative and nitrosative stress (O&NS) pathways play a role in the pathophysiology of myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS). There is also evidence that these neuroimmune diseases are accompanied by hypothalamic-pituitary-adrenal (HPA) axis hypoactivity as indicated by lowered baseline glucocorticoid levels. This paper aims to review the bidirectional communications between immune-inflammatory and O&NS pathways and HPA axis hypoactivity in ME/CFS, considering two possibilities: (a) Activation of immune-inflammatory pathways is secondary to HPA axis hypofunction via attenuated negative feedback mechanisms, or (b) chronic activated immune-inflammatory and O&NS pathways play a causative role in HPA axis hypoactivity. Electronic databases, i.e., PUBMED, Scopus, and Google Scholar, were used as sources for this narrative review by using keywords CFS, ME, cortisol, ACTH, CRH, HPA axis, glucocorticoid receptor, cytokines, immune, immunity, inflammation, and O&NS. Findings show that activation of immune-inflammatory and O&NS pathways in ME/CFS are probably not secondary to HPA axis hypoactivity and that activation of these pathways may underpin HPA axis hypofunction in ME/CFS. Mechanistic explanations comprise increased levels of tumor necrosis factor-α, T regulatory responses with elevated levels of interleukin-10 and transforming growth factor-β, elevated levels of nitric oxide, and viral/bacterial-mediated mechanisms. HPA axis hypoactivity in ME/CFS is most likely a consequence and not a cause of a wide variety of activated immune-inflammatory and O&NS pathways in that illness.

A three-axis flight simulator. [for testing and evaluating inertial measuring units, and flight platforms

NASA Technical Reports Server (NTRS)

Mason, M. G.

1975-01-01

A simulator is described, which was designed for testing and evaluating inertial measuring units, and flight platforms. Mechanical and electrical specifications for the outer, middle, and inner axis are presented. Test results are included.

Heliostat for astronomical usage

NASA Technical Reports Server (NTRS)

Heyde, G.

1979-01-01

The design of a heliostat is presented. The invention consists of a mechanical polar axis which can rotate and which is parallel to the world axis. A mirror is supported in such a way that it can be rotated arbitrarily around a declination axis which is perpendicular to it. After execution of this rotation, the mirror can be clamped in the plane of the world axis, which can be corrected and verified by special collimation directions. The clockwork or drive unit can be driven for a 24 or 48 hour complete rotation of the axis using any known device such as switchable gears, without changing its regular variation related to stellar time or mean solar time.

International Conference on the Mechanical Technology of Inertial Devices, University of Newcastle-upon-Tyne, England, Apr. 7-9, 1987, Proceedings

NASA Astrophysics Data System (ADS)

Various papers on the mechanical technology of inertial devices are presented. The topics addressed include: development of a directional gyroscope for remotely piloted vehicles and similar applications; a two-degree-of-freedom gyroscope with frictionless inner and outer gimbal pickoffs; oscillogyro design, manufacture, and performance; development of miniature two-axis rate gyroscope; mechanical design aspects of the electrostatically suspended gyroscope; role of gas-lubricated bearings in current and future sensors; development of a new microporous retainer material for precision ball bearings; design study for a high-stability, large-centrifuge test bed; evaluation of a two-axis rate gyro; operating principles of a two-axis angular rate transducer; and nutation frequency analysis. Also considered are: triaxial laser gyro; mechanical design considerations for a ring laser gyro dither mechanism; environmental considerations in the design of fiberoptic gyroscopes; manufacturing aspects of some critical high-precision mechanical components of inertial devices; dynamics and control of a gyroscopic force measurement system; high precision and high performance motion systems; use of multiple acceleration references to obtain high precision centrifuge data at low cost; gyro testing and evaluation at the Communications Research Centre; review of the mechanical design and development of a high-performance accelerometer; and silicon microengineering for accelerometers.

Percentage depth dose calculation accuracy of model based algorithms in high energy photon small fields through heterogeneous media and comparison with plastic scintillator dosimetry.

PubMed

Alagar, Ananda Giri Babu; Mani, Ganesh Kadirampatti; Karunakaran, Kaviarasu

2016-01-08

Small fields smaller than 4 × 4 cm2 are used in stereotactic and conformal treatments where heterogeneity is normally present. Since dose calculation accuracy in both small fields and heterogeneity often involves more discrepancy, algorithms used by treatment planning systems (TPS) should be evaluated for achieving better treatment results. This report aims at evaluating accuracy of four model-based algorithms, X-ray Voxel Monte Carlo (XVMC) from Monaco, Superposition (SP) from CMS-Xio, AcurosXB (AXB) and analytical anisotropic algorithm (AAA) from Eclipse are tested against the measurement. Measurements are done using Exradin W1 plastic scintillator in Solid Water phantom with heterogeneities like air, lung, bone, and aluminum, irradiated with 6 and 15 MV photons of square field size ranging from 1 to 4 cm2. Each heterogeneity is introduced individually at two different depths from depth-of-dose maximum (Dmax), one setup being nearer and another farther from the Dmax. The central axis percentage depth-dose (CADD) curve for each setup is measured separately and compared with the TPS algorithm calculated for the same setup. The percentage normalized root mean squared deviation (%NRMSD) is calculated, which represents the whole CADD curve's deviation against the measured. It is found that for air and lung heterogeneity, for both 6 and 15 MV, all algorithms show maximum deviation for field size 1 × 1 cm2 and gradually reduce when field size increases, except for AAA. For aluminum and bone, all algorithms' deviations are less for 15 MV irrespective of setup. In all heterogeneity setups, 1 × 1 cm2 field showed maximum deviation, except in 6MV bone setup. All algorithms in the study, irrespective of energy and field size, when any heterogeneity is nearer to Dmax, the dose deviation is higher compared to the same heterogeneity far from the Dmax. Also, all algorithms show maximum deviation in lower-density materials compared to high-density materials.

The impact of the fabrication method on the three-dimensional accuracy of an implant surgery template.

PubMed

Matta, Ragai-Edward; Bergauer, Bastian; Adler, Werner; Wichmann, Manfred; Nickenig, Hans-Joachim

2017-06-01

The use of a surgical template is a well-established method in advanced implantology. In addition to conventional fabrication, computer-aided design and computer-aided manufacturing (CAD/CAM) work-flow provides an opportunity to engineer implant drilling templates via a three-dimensional printer. In order to transfer the virtual planning to the oral situation, a highly accurate surgical guide is needed. The aim of this study was to evaluate the impact of the fabrication method on the three-dimensional accuracy. The same virtual planning based on a scanned plaster model was used to fabricate a conventional thermo-formed and a three-dimensional printed surgical guide for each of 13 patients (single tooth implants). Both templates were acquired individually on the respective plaster model using an optical industrial white-light scanner (ATOS II, GOM mbh, Braunschweig, Germany), and the virtual datasets were superimposed. Using the three-dimensional geometry of the implant sleeve, the deviation between both surgical guides was evaluated. The mean discrepancy of the angle was 3.479° (standard deviation, 1.904°) based on data from 13 patients. Concerning the three-dimensional position of the implant sleeve, the highest deviation was in the Z-axis at 0.594 mm. The mean deviation of the Euclidian distance, dxyz, was 0.864 mm. Although the two different fabrication methods delivered statistically significantly different templates, the deviations ranged within a decimillimeter span. Both methods are appropriate for clinical use. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Head-body righting reflex from the supine position and preparatory eye movements.

PubMed

Troiani, Diana; Ferraresi, Aldo; Manni, Ermanno

2005-05-01

Saccular and utricular maculae can provide information on the supine static position, considering that both have pronounced curved structures with hair cells having a variety of polarization vectors that enable them to sense an inverted position and thus direct the righting reflex. The vestibular system is essential for the structuring of motor behaviour, senses linear and angular acceleration and has a strong influence on posture and balance at rest, during locomotion and in head body righting reflexes. Using guinea pigs in the supine position with a symmetrical head and trunk position, the ocular position was analysed to ascertain whether any ocular movement that occurred would adopt a spatial deviation indicative of the subsequent head and body righting. The characteristics of the righting reflex (direction, latency, duration and velocity) were analysed in guinea pigs from position signals obtained from search coils implanted in the eye, head and pelvis. The animals were kept in a supine position for a few seconds or even minutes with the eyes in a stable primary position and the head and body symmetrical and immobile. The righting reflex took place either immediately or after a slow deviation of the eyes. In both cases the righting sequence (eyes, head, body) was stereotyped and consistent. The direction of head and body righting was along the longitudinal axis of the animal and was either clockwise or anticlockwise and the direction of righting was related to the direction of the eye deviation. The ocular deviation and the direction of deviation that initiated and determined the direction of the righting reflex could be explained by possible otolithic activation.

Validation and uncertainty quantification of detector response functions for a 1″×2″ NaI collimated detector intended for inverse radioisotope source mapping applications

DOE PAGES

Nelson, N.; Azmy, Y.; Gardner, R. P.; ...

2017-08-05

Detector response functions (DRFs) are often used for inverse analysis. We compute the DRF of a sodium iodide (NaI) nuclear material holdup field detector using the code named g03 developed by the Center for Engineering Applications of Radioisotopes (CEAR) at NC State University. Three measurement campaigns were performed in order to validate the DRF’s constructed by g03: on-axis detection of calibration sources, off-axis measurements of a highly enriched uranium (HEU) disk, and on-axis measurements of the HEU disk with steel plates inserted between the source and the detector to provide attenuation. Furthermore, this work quantifies the uncertainty of the Montemore » Carlo simulations used in and with g03, as well as the uncertainties associated with each semi-empirical model employed in the full DRF rep-resentation. Overall, for the calibration source measurements, the response computed by the DRF for the prediction of the full-energy peak region of responses was good, i.e. within two standard deviations of the experimental response. In contrast, the DRF tended to overestimate the Compton continuum by about 45–65% due to inadequate tuning of the electron range multiplier fit variable that empirically represents physics associated with electron transport that is not modeled explicitly in g03. For the HEU disk mea-surements, computed DRF responses tended to significantly underestimate (more than 20%) the sec-ondary full-energy peaks (any peak of lower energy than the highest-energy peak computed) due to scattering in the detector collimator and aluminum can, which is not included in the g03 model. We ran a sufficiently large number of histories to ensure for all of the Monte Carlo simulations that the sta-tistical uncertainties were lower than their experimental counterpart’s Poisson uncertainties. The uncer-tainties associated with least-squares fits to the experimental data tended to have parameter relative standard deviations lower than the peak channel relative standard deviation in most cases and good reduced chi-square values. The highest sources of uncertainty were identified as the energy calibration polynomial factor (due to limited source availability and NaI resolution) and the Ba-133 peak fit (only a very weak source was available), which were 20% and 10%, respectively.« less

Validation and uncertainty quantification of detector response functions for a 1″×2″ NaI collimated detector intended for inverse radioisotope source mapping applications

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

Nelson, N.; Azmy, Y.; Gardner, R. P.

Detector response functions (DRFs) are often used for inverse analysis. We compute the DRF of a sodium iodide (NaI) nuclear material holdup field detector using the code named g03 developed by the Center for Engineering Applications of Radioisotopes (CEAR) at NC State University. Three measurement campaigns were performed in order to validate the DRF’s constructed by g03: on-axis detection of calibration sources, off-axis measurements of a highly enriched uranium (HEU) disk, and on-axis measurements of the HEU disk with steel plates inserted between the source and the detector to provide attenuation. Furthermore, this work quantifies the uncertainty of the Montemore » Carlo simulations used in and with g03, as well as the uncertainties associated with each semi-empirical model employed in the full DRF rep-resentation. Overall, for the calibration source measurements, the response computed by the DRF for the prediction of the full-energy peak region of responses was good, i.e. within two standard deviations of the experimental response. In contrast, the DRF tended to overestimate the Compton continuum by about 45–65% due to inadequate tuning of the electron range multiplier fit variable that empirically represents physics associated with electron transport that is not modeled explicitly in g03. For the HEU disk mea-surements, computed DRF responses tended to significantly underestimate (more than 20%) the sec-ondary full-energy peaks (any peak of lower energy than the highest-energy peak computed) due to scattering in the detector collimator and aluminum can, which is not included in the g03 model. We ran a sufficiently large number of histories to ensure for all of the Monte Carlo simulations that the sta-tistical uncertainties were lower than their experimental counterpart’s Poisson uncertainties. The uncer-tainties associated with least-squares fits to the experimental data tended to have parameter relative standard deviations lower than the peak channel relative standard deviation in most cases and good reduced chi-square values. The highest sources of uncertainty were identified as the energy calibration polynomial factor (due to limited source availability and NaI resolution) and the Ba-133 peak fit (only a very weak source was available), which were 20% and 10%, respectively.« less

X- And y-axis driver for rotating microspheres

DOEpatents

Weinstein, Berthold W.

1979-01-01

Apparatus for precise control of the motion and position of microspheres for examination of their interior and/or exterior. The apparatus includes an x- and y-axis driver mechanism controlled, for example, by a minicomputer for selectively rotating microspheres retained between a pair of manipulator arms having flat, smooth end surfaces. The driver mechanism includes an apertured plate and ball arrangement which provided for coupled equal and opposite movement of the manipulator arms in two perpendicular directions.

Tunable Spectrum Selectivity for Multiphoton Absorption with Enhanced Visible Light Trapping in ZnO Nanorods.

PubMed

Tan, Kok Hong; Lim, Fang Sheng; Toh, Alfred Zhen Yang; Zheng, Xia-Xi; Dee, Chang Fu; Majlis, Burhanuddin Yeop; Chai, Siang-Piao; Chang, Wei Sea

2018-04-17

Observation of visible light trapping in zinc oxide (ZnO) nanorods (NRs) correlated to the optical and photoelectrochemical properties is reported. In this study, ZnO NR diameter and c-axis length respond primarily at two different regions, UV and visible light, respectively. ZnO NR diameter exhibits UV absorption where large ZnO NR diameter area increases light absorption ability leading to high efficient electron-hole pair separation. On the other hand, ZnO NR c-axis length has a dominant effect in visible light resulting from a multiphoton absorption mechanism due to light reflection and trapping behavior in the free space between adjacent ZnO NRs. Furthermore, oxygen vacancies and defects in ZnO NRs are associated with the broad visible emission band of different energy levels also highlighting the possibility of the multiphoton absorption mechanism. It is demonstrated that the minimum average of ZnO NR c-axis length must satisfy the linear regression model of Z p,min = 6.31d to initiate the multiphoton absorption mechanism under visible light. This work indicates the broadening of absorption spectrum from UV to visible light region by incorporating a controllable diameter and c-axis length on vertically aligned ZnO NRs, which is important in optimizing the design and functionality of electronic devices based on light absorption mechanism. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemokine GPCR Signaling Inhibits β-Catenin during Zebrafish Axis Formation

PubMed Central

Wu, Shu-Yu; Shin, Jimann; Sepich, Diane S.; Solnica-Krezel, Lilianna

2012-01-01

Embryonic axis formation in vertebrates is initiated by the establishment of the dorsal Nieuwkoop blastula organizer, marked by the nuclear accumulation of maternal β-catenin, a transcriptional effector of canonical Wnt signaling. Known regulators of axis specification include the canonical Wnt pathway components that positively or negatively affect β-catenin. An involvement of G-protein coupled receptors (GPCRs) was hypothesized from experiments implicating G proteins and intracellular calcium in axis formation, but such GPCRs have not been identified. Mobilization of intracellular Ca2+ stores generates Ca2+ transients in the superficial blastomeres of zebrafish blastulae when the nuclear accumulation of maternal β-catenin marks the formation of the Nieuwkoop organizer. Moreover, intracellular Ca2+ downstream of non-canonical Wnt ligands was proposed to inhibit β-catenin and axis formation, but mechanisms remain unclear. Here we report a novel function of Ccr7 GPCR and its chemokine ligand Ccl19.1, previously implicated in chemotaxis and other responses of dendritic cells in mammals, as negative regulators of β-catenin and axis formation in zebrafish. We show that interference with the maternally and ubiquitously expressed zebrafish Ccr7 or Ccl19.1 expands the blastula organizer and the dorsoanterior tissues at the expense of the ventroposterior ones. Conversely, Ccr7 or Ccl19.1 overexpression limits axis formation. Epistatic analyses demonstrate that Ccr7 acts downstream of Ccl19.1 ligand and upstream of β-catenin transcriptional targets. Moreover, Ccl19/Ccr7 signaling reduces the level and nuclear accumulation of maternal β-catenin and its axis-inducing activity and can also inhibit the Gsk3β -insensitive form of β-catenin. Mutational and pharmacologic experiments reveal that Ccr7 functions during axis formation as a GPCR to inhibit β-catenin, likely by promoting Ca2+ transients throughout the blastula. Our study delineates a novel negative, Gsk3β-independent control mechanism of β-catenin and implicates Ccr7 as a long-hypothesized GPCR regulating vertebrate axis formation. PMID:23055828

Effects of an Off-Axis Pivoting Elliptical Training Program on Gait Function in Persons With Spastic Cerebral Palsy: A Preliminary Study.

PubMed

Tsai, Liang-Ching; Ren, Yupeng; Gaebler-Spira, Deborah J; Revivo, Gadi A; Zhang, Li-Qun

2017-07-01

This preliminary study examined the effects of off-axis elliptical training on reducing transverse-plane gait deviations and improving gait function in 8 individuals with cerebral palsy (CP) (15.5 ± 4.1 years) who completed an training program using a custom-made elliptical trainer that allows transverse-plane pivoting of the footplates during exercise. Lower-extremity off-axis control during elliptical exercise was evaluated by quantifying the root-mean-square and maximal angular displacement of the footplate pivoting angle. Lower-extremity pivoting strength was assessed. Gait function and balance were evaluated using 10-m walk test, 6-minute-walk test, and Pediatric Balance Scale. Toe-in angles during gait were quantified. Participants with CP demonstrated a significant decrease in the pivoting angle (root mean square and maximal angular displacement; effect size, 1.00-2.00) and increase in the lower-extremity pivoting strength (effect size = 0.91-1.09) after training. Reduced 10-m walk test time (11.9 ± 3.7 seconds vs. 10.8 ± 3.0 seconds; P = 0.004; effect size = 1.46), increased Pediatric Balance Scale score (43.6 ± 12.9 vs. 45.6 ± 10.8; P = 0.042; effect size = 0.79), and decreased toe-in angle (3.7 ± 10.5 degrees vs. 0.7 ± 11.7 degrees; P = 0.011; effect size = 1.22) were observed after training. We present an intervention to challenge lower-extremity off-axis control during a weight-bearing and functional activity for individuals with CP. Our preliminary findings suggest that this intervention was effective in enhancing off-axis control, gait function, and balance and reducing in-toeing gait in persons with CP.

Repeated swim impairs serotonin clearance via a corticosterone-sensitive mechanism: organic cation transporter 3, the smoking gun.

PubMed

Baganz, Nicole; Horton, Rebecca; Martin, Kathryn; Holmes, Andrew; Daws, Lynette C

2010-11-10

Activation of the hypothalamic-pituitary-adrenal (HPA) axis is associated with increased extracellular serotonin (5-HT) in limbic brain regions. The mechanism through which this occurs remains unclear. One way could be via HPA axis-dependent impairment of serotonin transporter (SERT) function, the high-affinity uptake mechanism for 5-HT. Consistent with this idea, we found that 5-HT clearance rate in hippocampus was dramatically reduced in mice exposed to repeated swim, a stimulus known to activate the HPA axis. However, this phenomenon also occurred in mice lacking SERT, ruling out SERT as a mechanism. The organic cation transporter 3 (OCT3) is emerging as an important regulator of brain 5-HT. Moreover, corticosterone, which is released upon HPA axis activation, blocks 5-HT uptake by OCT3. Repeated swim produced a persistent elevation in plasma corticosterone, and, consistent with prolonged blockade by corticosterone, we found that OCT3 expression and function were reduced in these mice. Importantly, this effect of repeated swim to reduce 5-HT clearance rate was corticosterone dependent, as evidenced by its absence in adrenalectomized mice, in which plasma corticosterone levels were essentially undetectable. Behaviorally, mice subjected to repeated swim spent less time immobile in the tail suspension test than control mice, but responded similarly to SERT- and norepinephrine transporter-selective antidepressants. Together, these results show that reduced 5-HT clearance following HPA axis activation is likely mediated, at least in part, by the corticosterone-sensitive OCT3, and that drugs developed to selectively target OCT3 (unlike corticosterone) may be candidates for the development of novel antidepressant medications.

Morphometric analyses of hominoid crania, probabilities of conspecificity and an approximation of a biological species constant.

PubMed

Thackeray, J F; Dykes, S

2016-02-01

Thackeray has previously explored the possibility of using a morphometric approach to quantify the "amount" of variation within species and to assess probabilities of conspecificity when two fossil specimens are compared, instead of "pigeon-holing" them into discrete species. In an attempt to obtain a statistical (probabilistic) definition of a species, Thackeray has recognized an approximation of a biological species constant (T=-1.61) based on the log-transformed standard error of the coefficient m (log sem) in regression analysis of cranial and other data from pairs of specimens of conspecific extant species, associated with regression equations of the form y=mx+c where m is the slope and c is the intercept, using measurements of any specimen A (x axis), and any specimen B of the same species (y axis). The log-transformed standard error of the co-efficient m (log sem) is a measure of the degree of similarity between pairs of specimens, and in this study shows central tendency around a mean value of -1.61 and standard deviation 0.10 for modern conspecific specimens. In this paper we focus attention on the need to take into account the range of difference in log sem values (Δlog sem or "delta log sem") obtained from comparisons when specimen A (x axis) is compared to B (y axis), and secondly when specimen A (y axis) is compared to B (x axis). Thackeray's approach can be refined to focus on high probabilities of conspecificity for pairs of specimens for which log sem is less than -1.61 and for which Δlog sem is less than 0.03. We appeal for the adoption of a concept here called "sigma taxonomy" (as opposed to "alpha taxonomy"), recognizing that boundaries between species are not always well defined. Copyright © 2015 Elsevier GmbH. All rights reserved.

Biological mechanisms of premature ovarian failure caused by psychological stress based on support vector regression

PubMed Central

Wang, Xiu-Feng; Zhang, Lei; Wu, Qing-Hua; Min, Jian-Xin; Ma, Na; Luo, Lai-Cheng

2015-01-01

Psychological stress has become a common and important cause of premature ovarian failure (POF). Therefore, it is very important to explore the mechanisms of POF resulting from psychological stress. Sixty SD rats were randomly divided into control and model groups. Biomolecules associated with POF (β-EP, IL-1, NOS, NO, GnRH, CRH, FSH, LH, E2, P, ACTH, and CORT) were measured in the control and psychologically stressed rats. The regulation relationships of the biomolecules were explored in the psychologically stressed state using support vector regression (SVR). The values of β-EP, IL-1, NOS, and GnRH in the hypothalamus decreased significantly, and the value of NO changed slightly, when the values of 3 biomolecules in the hypothalamic-pituitary-adrenal axis decreased. The values of E2 and P in the hypothalamic-pituitary-ovarian axis decreased significantly, while the values of FSH and LH changed slightly, when the values of the biomolecules in the hypothalamus decreased. The values of FSH and LH in the pituitary layer of the hypothalamic-pituitary-ovarian axis changed slightly when the values of E2 and P in the target gland layer of the hypothalamic-pituitary-ovarian axis decreased. An Imbalance in the neuroendocrine-immune bimolecular network, particularly the failure of the feedback action of the target gland layer to pituitary layer in the pituitary-ovarian axis, is possibly one of the pathogenic mechanisms of POF. PMID:26885082

Maternal lipids in pregnancy are associated with increased offspring cortisol reactivity in childhood.

PubMed

Mina, Theresia H; Lahti, Marius; Drake, Amanda J; Forbes, Shareen; Denison, Fiona C; Räikkönen, Katri; Norman, Jane E; Reynolds, Rebecca M

2017-09-01

Prenatal programming of hypothalamic-pituitary-adrenal (HPA) axis activity has long term implications for offspring health. Biological mechanisms underlying programming of the offspring HPA axis are poorly understood. We hypothesised that altered maternal metabolism including higher maternal obesity, glucose and lipids are novel programming factors for altered offspring HPA axis activity. Salivary cortisol levels were measured in 54 children aged 3-5 years under experimental conditions (before and after a delay of self-gratification test). Associations of child cortisol responses with maternal obesity in early pregnancy and with fasting glucose, triglycerides, HDL and total cholesterol measured in each pregnancy trimester were tested. Higher levels of maternal triglycerides and total cholesterol throughout pregnancy were associated with increased offspring cortisol reactivity. The associations were independent of maternal obesity and other confounders, suggesting that exposure to maternal lipids could be a biological mechanism of in utero programming of the offspring's HPA axis. Copyright © 2017. Published by Elsevier Ltd.

Antagonistic Self-Organizing Patterning Systems Control Maintenance and Regeneration of the Anteroposterior Axis in Planarians.

PubMed

Stückemann, Tom; Cleland, James Patrick; Werner, Steffen; Thi-Kim Vu, Hanh; Bayersdorf, Robert; Liu, Shang-Yun; Friedrich, Benjamin; Jülicher, Frank; Rink, Jochen Christian

2017-02-06

Planarian flatworms maintain their body plan in the face of constant internal turnover and can regenerate from arbitrary tissue fragments. Both phenomena require self-maintaining and self-organizing patterning mechanisms, the molecular mechanisms of which remain poorly understood. We show that a morphogenic gradient of canonical Wnt signaling patterns gene expression along the planarian anteroposterior (A/P) axis. Our results demonstrate that gradient formation likely occurs autonomously in the tail and that an autoregulatory module of Wnt-mediated Wnt expression both shapes the gradient at steady state and governs its re-establishment during regeneration. Functional antagonism between the tail Wnt gradient and an unknown head patterning system further determines the spatial proportions of the planarian A/P axis and mediates mutually exclusive molecular fate choices during regeneration. Overall, our results suggest that the planarian A/P axis is patterned by self-organizing patterning systems deployed from either end that are functionally coupled by mutual antagonism. Copyright © 2017 Elsevier Inc. All rights reserved.

The zebrafish dorsal axis is apparent at the four-cell stage.

PubMed

Gore, Aniket V; Maegawa, Shingo; Cheong, Albert; Gilligan, Patrick C; Weinberg, Eric S; Sampath, Karuna

2005-12-15

A central question in the development of multicellular organisms pertains to the timing and mechanisms of specification of the embryonic axes. In many organisms, specification of the dorsoventral axis requires signalling by proteins of the Transforming growth factor-beta and Wnt families. Here we show that maternal transcripts of the zebrafish Nodal-related morphogen, Squint (Sqt), can localize to two blastomeres at the four-cell stage and predict the dorsal axis. Removal of cells containing sqt transcripts from four-to-eight-cell embryos or injection of antisense morpholino oligonucleotides targeting sqt into oocytes can cause a loss of dorsal structures. Localization of sqt transcripts is independent of maternal Wnt pathway function and requires a highly conserved sequence in the 3' untranslated region. Thus, the dorsoventral axis is apparent by early cleavage stages and may require the maternally encoded morphogen Sqt and its associated factors. Because the 3' untranslated region of the human nodal gene can also localize exogenous sequences to dorsal cells, this mechanism may be evolutionarily conserved.

Atomic force microscopy capable of vibration isolation with low-stiffness Z-axis actuation.

PubMed

Ito, Shingo; Schitter, Georg

2018-03-01

For high-resolution imaging without bulky external vibration isolation, this paper presents an atomic force microscope (AFM) capable of vibration isolation with its internal Z-axis (vertical) actuators moving the AFM probe. Lorentz actuators (voice coil actuators) are used for the Z-axis actuation, and flexures guiding the motion are designed to have a low stiffness between the mover and the base. The low stiffness enables a large Z-axis actuation of more than 700 µm and mechanically isolates the probe from floor vibrations at high frequencies. To reject the residual vibrations, the probe tracks the sample by using a displacement sensor for feedback control. Unlike conventional AFMs, the Z-axis actuation attains a closed-loop control bandwidth that is 35 times higher than the first mechanical resonant frequency. The closed-loop AFM system has robustness against the flexures' nonlinearity and uses the first resonance for better sample tracking. For further improvement, feedforward control with a vibration sensor is combined, and the resulting system rejects 98.4% of vibrations by turning on the controllers. The AFM system is demonstrated by successful AFM imaging in a vibrational environment. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis of a planetary-rotation system for evaporated optical coatings.

PubMed

Oliver, J B

2016-10-20

The impact of planetary design considerations for optical coating deposition is analyzed, including the ideal number of planets, variations in system performance, and the deviation of planet motion from the ideal. System capacity is maximized for four planets, although substrate size can significantly influence this result. Guidance is provided in the design of high-performance deposition systems based on the relative impact of different error modes. Errors in planet mounting such that the planet surface is not perpendicular to the axis of rotation are particularly problematic, suggesting planetary design modifications would be appropriate.

N-(2-Allyl-4-eth-oxy-2H-indazol-5-yl)-4-methyl-benzene-sulfonamide.

PubMed

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Viale, Maurizio; Saadi, Mohamed; El Ammari, Lahcen

2014-05-01

The indazole ring system of the title compound, C19H21N3O3S, is almost planar (r.m.s. deviation = 0.0192 Å) and forms dihedral angles of 77.99 (15) and 83.9 (3)° with the benzene ring and allyl group, respectively. In the crystal, centrosymmetrically related mol-ecules are connected by pairs of N-H⋯O hydrogen bonds into dimers, which are further linked by C-H⋯O hydrogen bonds, forming columns parallel to the b axis.

Considerations on the mechanisms of alternating skew deviation in patients with cerebellar lesions.

PubMed

Zee, D S

1996-01-01

Alternating skew deviation, in which the side of the higher eye changes depending upon whether gaze is directed to the left or the right, is a frequent sign in patients with posterior fossa lesions, including those restricted to the cerebellum. Here we propose a mechanism for alternating skews related to the otolith-ocular responses to fore and aft pitch of the head in lateral-eyed animals. In lateral-eyed animals the expected response to a static head pitch is cyclorotation of the eyes. But if the eyes are rotated horizontally in the orbit, away from the primary position, a compensatory skew deviation should also appear. The direction of the skew would depend upon whether the eyes were directed to the right (left eye forward, right eye backward) or to the left (left eye backward, right eye forward). In contrast, for frontal-eyed animals, skew deviations are counterproductive because they create diplopia and interfere with binocular vision. We attribute the emergence of skew deviations in frontal-eyed animals in pathological conditions to 1) an imbalance in otolithocular pathways and 2) a loss of the component of ocular motor innervation that normally corrects for the differences in pulling directions and strengths of the various ocular muscles as the eyes change position in the orbit. Such a compensatory mechanism is necessary to ensure optimal binocular visual function during and after head motion. This compensatory mechanism may depend upon the cerebellum.

Role of electrocardiographic changes in discriminating acute or chronic right ventricular pressure overload.

PubMed

Can, Mehmet Mustafa; Özveren, Olcay; Biteker, Murat; Şengül, Cihan; Uz, Ömer; Işılak, Zafer; Kırılmaz, Ata

2013-06-01

Pulmonary embolism (PE) and severe pulmonary stenosis (PS) are two distinct conditions accompanied by increased pressure load of the right ventricle (RV). Despite major advances in our understanding of the mechanisms of RV adaptation to the increased pressure, substantial gaps in our knowledge remain unsettled. One of much less known aspect of pressure overload of RV is its impact on electrocardiographic (ECG) changes. In this study, we aimed to study whether acute and chronic RV overload are accompanied by different ECG patterns. Thirty-eight patients with PE underwent ECG monitoring were compared with 20 matched patients with PS in this observational retrospective study. ECG abnormalities suggestive of RV overload were recorded and analyzed in both groups. Logistic regression analysis was used to define the predictors of chronic RV overload. Among the ECG changes studied, premature atrial contraction (OR-12.2, 95% CI, 1.3-107, p=0.008), right axis deviation (OR-20.4, 95% CI 4.2-98, p<0.001), indeterminate axis (OR-0.11, 95% CI 0.02-0.44, p=0.001 0.11), incomplete right bundle branch block (OR-4.2, 95% CI, 1.1-15.4, p=0.02), late R in aVR (OR-8.4, 95% CI 2.1-33.2, p=0.001), qR in V1 lead (OR-8.3, 95% CI 1.2-74.8, p=0.03) were found to be the independent predictors of chronic RV pressure overload. Our data indicate that the ECG changes that attributed to the acute RV pressure loading states may be more prevalent in chronic RV overload as compared with acute RV overload.

Estimation of power in low velocity vertical axis wind turbine

NASA Astrophysics Data System (ADS)

Sampath, S. S.; Shetty, Sawan; Chithirai Pon Selvan, M.

2015-06-01

The present work involves in the construction of a vertical axis wind turbine and the determination of power. Various different types of turbine blades are considered and the optimum blade is selected. Mechanical components of the entire setup are built to obtain maximum rotation per minute. The mechanical energy is converted into the electrical energy by coupling coaxially between the shaft and the generator. This setup produces sufficient power for consumption of household purposes which is economic and easily available.

Negative energy balance in a male songbird, the Abert's towhee, constrains the testicular endocrine response to luteinizing hormone stimulation

PubMed Central

Davies, Scott; Gao, Sisi; Valle, Shelley; Bittner, Stephanie; Hutton, Pierce; Meddle, Simone L.; Deviche, Pierre

2015-01-01

ABSTRACT Energy deficiency can suppress reproductive function in vertebrates. As the orchestrator of reproductive function, endocrine activity of the hypothalamo-pituitary–gonadal (HPG) axis is potentially an important mechanism mediating such effects. Previous experiments in wild-caught birds found inconsistent relationships between energy deficiency and seasonal reproductive function, but these experiments focused on baseline HPG axis activity and none have investigated the responsiveness of this axis to endocrine stimulation. Here, we present data from an experiment in Abert's towhees, Melozone aberti, using gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) challenges to investigate whether energy deficiency modulates the plasma testosterone responsiveness of the HPG axis. Wild-caught birds were either ad libitum fed or energetically constrained via chronic food restriction during photoinduced reproductive development. Energy deficiency did not significantly affect the development of reproductive morphology, the baseline endocrine activity of the HPG axis, or the plasma testosterone response to GnRH challenge. Energy deficiency did, however, decrease the plasma testosterone responsiveness to LH challenge. Collectively, these observations suggest that energy deficiency has direct gonadal effects consisting of a decreased responsiveness to LH stimulation. Our study, therefore, reveals a mechanism by which energy deficiency modulates reproductive function in wild birds in the absence of detectable effects on baseline HPG axis activity. PMID:26333925

Negative energy balance in a male songbird, the Abert's Towhee, constrains the testicular endocrine response to luteinizing hormone stimulation.

PubMed

Davies, Scott; Gao, Sisi; Valle, Shelley; Bittner, Stephanie; Hutton, Pierce; Meddle, Simone L; Deviche, Pierre

2015-07-10

Energy deficiency can suppress reproductive functions in vertebrates. As the orchestrator of reproductive function, endocrine activity of the hypothalamo-pituitary-gonadal (HPG) axis is potentially an important mechanism mediating such effects. Previous experiments in wild-caught birds found inconsistent relationships between energy deficiency and seasonal reproductive function, but these experiments focused on baseline HPG axis activity and none has investigated the responsiveness of this axis to endocrine stimulation. Here, we present data from an experiment in Abert's Towhees, Melozone aberti, using gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) challenges to investigate whether energy deficiency modulates the plasma testosterone (T) responsiveness of the HPG axis. Wild-caught birds were either ad libitum-fed or energetically constrained via chronic food restriction during photoinduced reproductive development. Energy deficiency did not significantly affect the development of reproductive morphology, the baseline endocrine activity of the HPG axis, or the plasma T response to GnRH challenge. Energy deficiency did, however, decrease the plasma T responsiveness to LH challenge. Collectively, these observations suggest that energy deficiency has direct gonadal effects consisting in decreased responsiveness to LH stimulation. Our study, therefore, reveals a mechanism by which energy deficiency modulates reproductive function in wild birds in the absence of detectable effects on baseline HPG axis activity. © 2015. Published by The Company of Biologists Ltd.

Negative energy balance in a male songbird, the Abert's towhee, constrains the testicular endocrine response to luteinizing hormone stimulation.

PubMed

Davies, Scott; Gao, Sisi; Valle, Shelley; Bittner, Stephanie; Hutton, Pierce; Meddle, Simone L; Deviche, Pierre

2015-09-01

Energy deficiency can suppress reproductive function in vertebrates. As the orchestrator of reproductive function, endocrine activity of the hypothalamo-pituitary-gonadal (HPG) axis is potentially an important mechanism mediating such effects. Previous experiments in wild-caught birds found inconsistent relationships between energy deficiency and seasonal reproductive function, but these experiments focused on baseline HPG axis activity and none have investigated the responsiveness of this axis to endocrine stimulation. Here, we present data from an experiment in Abert's towhees, Melozone aberti, using gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) challenges to investigate whether energy deficiency modulates the plasma testosterone responsiveness of the HPG axis. Wild-caught birds were either ad libitum fed or energetically constrained via chronic food restriction during photoinduced reproductive development. Energy deficiency did not significantly affect the development of reproductive morphology, the baseline endocrine activity of the HPG axis, or the plasma testosterone response to GnRH challenge. Energy deficiency did, however, decrease the plasma testosterone responsiveness to LH challenge. Collectively, these observations suggest that energy deficiency has direct gonadal effects consisting of a decreased responsiveness to LH stimulation. Our study, therefore, reveals a mechanism by which energy deficiency modulates reproductive function in wild birds in the absence of detectable effects on baseline HPG axis activity. © 2015. Published by The Company of Biologists Ltd.

Correction of axial deformity during lengthening in fibular hypoplasia: Hexapodal versus monorail external fixation.

PubMed

Chalopin, A; Geffroy, L; Pesenti, S; Hamel, A; Launay, F

2017-09-01

Childhood fibular hypoplasia is a rare pathology which may or may not involve limb-length discrepancy and axial deformity in one or more dimensions. The objective of the present study was to compare the quality of the axial correction achieved in lengthening procedures by hexapodal versus monorail external fixators. The hypothesis was that the hexapodal fixator provides more precise correction. A retrospective multicenter study included 52 children with fibular hypoplasia. Seventy-two tibias were analyzed, in 2 groups: 52 using a hexapodal fixator, and 20 using a monorail fixator. Mean age was 10.2 years. Mean lengthening was 5.7cm. Deformities were analyzed and measured in 3 dimensions and classified in 4 preoperative types and 4 post-lengthening types according to residual deformity. Complete correction was achieved in 26 tibias in the hexapodal group (50%) and 2 tibias in the monorail group (10%). Mean post-correction mechanical axis deviation was smaller in the hexapodal group: 12.83mm, versus 14.29mm in the monorail group. Mean post-correction mechanical lateral distal femoral angle was 87.5° in the hexapodal group, versus 84.3° in the monorail group (P=0.002), and mean mechanical medial proximal tibial angle 86.9° versus 89.5°, respectively (P=0.015). No previous studies focused on this congenital pathology in lengthening and axial correction programs for childhood lower-limb deformity. The present study found the hexapodal fixator to be more effective in conserving or restoring mechanical axes during progressive bone lengthening for fibular hypoplasia. The hexapodal fixator met the requirements of limb-length equalization in childhood congenital lower-limb hypoplasia, providing better axial correction than the monorail fixator. IV. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Image acquisition device of inspection robot based on adaptive rotation regulation of polarizer

NASA Astrophysics Data System (ADS)

Dong, Maoqi; Wang, Xingguang; Liang, Tao; Yang, Guoqing; Zhang, Chuangyou; Gao, Faqin

2017-12-01

An image processing device of inspection robot with adaptive polarization adjustment is proposed, that the device includes the inspection robot body, the image collecting mechanism, the polarizer and the polarizer automatic actuating device. Where, the image acquisition mechanism is arranged at the front of the inspection robot body for collecting equipment image data in the substation. Polarizer is fixed on the automatic actuating device of polarizer, and installed in front of the image acquisition mechanism, and that the optical axis of the camera vertically goes through the polarizer and the polarizer rotates with the optical axis of the visible camera as the central axis. The simulation results show that the system solves the fuzzy problems of the equipment that are caused by glare, reflection of light and shadow, and the robot can observe details of the running status of electrical equipment. And the full coverage of the substation equipment inspection robot observation target is achieved, which ensures the safe operation of the substation equipment.

Mechanics of damping for fiber composite laminates including hygro-thermal effects

NASA Technical Reports Server (NTRS)

Saravanos, D. A.; Chamis, C. C.

1989-01-01

An integrated mechanics theory has been developed for the modeling of composite damping from the micromechanics to the laminate level. Simplified, design oriented equations based on hysteretic damping are presented for on-axis plies, off-axis plies, and laminates including the effect of temperature, moisture, and interply hysteretic damping. The temperature rise within vibrating composite laminates resulting from strain energy dissipation is also modeled, and their coupled hygro-thermo-mechanical response is predicted. The method correlates well with reported damping measurements. Application examples illustrate the effect of various ply, laminate, and hygro-thermal parameters on the overall damping performance of composite laminates.

Mechanics of damping for fiber composite laminates including hygro-thermal effects

NASA Technical Reports Server (NTRS)

Saravanos, D. A.; Chamis, Christos C.

1989-01-01

An integrated mechanics theory was developed for the modeling of composite damping from the micromechanics to the laminate level. Simplified, design oriented equations based on hysteretic damping are presented for on-axis plies, off-axis plies, and laminates including the effect of temperature, moisture, and interply hysteretic damping. The temperature rise within vibrating composite laminates resulting from strain energy dissipation is also modeled, and their coupled hygro-thermo-mechanical response is predicted. The method correlates well with reported damping measurements. Application examples illustrate the effect of various ply, laminate, and hygro-thermal parameters on the overall damping performance of composite laminates.

The Effect of Sliding Humeral Osteotomy (SHO) on Frontal Plane Thoracic Limb Alignment: An Ex Vivo Canine Cadaveric Study.

PubMed

Breiteneicher, Adam H; Norby, Bo; Schulz, Kurt S; Kerwin, Sharon C; Hulse, Don A; Fox, Derek B; Saunders, W Brian

2016-11-01

To determine the effect of sliding humeral osteotomy (SHO) on frontal plane thoracic limb alignment in standing and recumbent limb positions. Canine cadaveric study. Canine thoracic limbs (n=15 limb pairs). Limbs acquired from healthy Labrador Retrievers euthanatized for reasons unrelated to this study were mounted in a limb press and aligned in a standing position followed by axial loading at 30% body weight. Frontal plane radiography was performed in standing and recumbent positions pre- and post-SHO. In the standing position, lateralization of the foot was measured pre- and post-SHO using a textured grid secured to the limb press base plate. Twelve thoracic limb alignment values (mean ± SD and 95% CI) were determined using the center of rotation of angulation (CORA) method were compared using linear mixed models to determine if significant differences existed between limb alignment values pre- or post-SHO, controlling for dog, limb, and limb position. Six of 12 standing or recumbent alignment values were significantly different pre- and post-SHO. SHO resulted in decreased mechanical lateral distal humeral angle and movement of the mechanical humeral radio-ulnar angle, radio-ulnar metacarpal angle, thoracic humeral angle, and elbow mechanical axis deviation toward coaxial limb alignment. In the standing position, the foot underwent significant lateralization post-SHO. SHO resulted in significant alteration in frontal plane thoracic limb alignment. Additional studies are necessary to determine if the changes reported using our ex vivo model occur following SHO in vivo. © Copyright 2016 by The American College of Veterinary Surgeons.

Steerable vertical to horizontal energy transducer for mobile robots

DOEpatents

Spletzer, Barry L.; Fischer, Gary J.; Feddema, John T.

2001-01-01

The present invention provides a steerable vertical to horizontal energy transducer for mobile robots that less complex and requires less power than two degree of freedom tilt mechanisms. The present invention comprises an end effector that, when mounted with a hopping actuator, translates along axis (typically vertical) actuation into combined vertical and horizontal motion. The end effector, or foot, mounts with an end of the actuator that moves toward the support surface (typically a floor or the earth). The foot is shaped so that the first contact with the support surface is off the axis of the actuator. Off-axis contact with the support surface generates an on-axis force (typically resulting in vertical motion) and a moment orthogonal to the axis. The moment initiates a horizontal tumbling motion, and tilts the actuator so that its axis is oriented with a horizontal component and continued actuation generates both vertical and horizontal force.

Apparatus and method for delivering a fluid to a container

DOEpatents

Turner, Terry D.

2002-01-01

An apparatus for delivering a fluid into a container has a carriage movably associated with a holding mechanism along an axis. A piston is attached to the carriage and a cylinder is slidably attached to the piston along the axis. The cylinder has a hole formed therein that extends along the axis. A needle extending along the axis is attached to the piston and passes through the cylinder hole. The needle has a first operative position relative to the piston when the needle is retracted within the cylinder and a second operative position relative to the piston when the needle extends from the cylinder.

Longitudinal shapes of the tibia and femur are unrelated and variable.

PubMed

Howell, Stephen M; Kuznik, Kyle; Hull, Maury L; Siston, Robert A

2010-04-01

In general practice, short films of the knee are used to assess component position and define the entry point for intramedullary femoral alignment in TKAs; however, whether it is justified to use the short film commonly used in research settings and everyday practice as a substitute for the whole leg view is controversial and needs clarification. In 138 long leg CT scanograms we measured the angle formed by the anatomic axis of the proximal fourth of the tibia and the mechanical axis of the tibia, the angle formed by the anatomic axis of the distal fourth of the femur and the mechanical axis of the femur, the "bow" of the tibia (as reflected by the offset of the anatomic axis from the center of the talus), and the "bow" of the femur (as reflected by the offset of the anatomic axis from the center of the femoral head). Because the angle formed by these axes and the bow of the tibia and femur have wide variability in females and males, a short film of the knee should not be used in place of the whole leg view when accurate assessment of component position and limb alignment is essential. A previous study of normal limbs found that only 2% of subjects have a neutral hip-knee-ankle axis, which can be explained by the wide variability of the bow in the tibia and femur and the lack of correlation between the bow of the tibia and femur in a given limb as shown in the current study.

Understanding misfit strain releasing mechanisms via molecular dynamics simulations of CdTe growth on {112}zinc-blende CdS

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

Zhou, Xiaowang; Chavez, Jose J.; Almeida, Sergio F.

Molecular dynamics simulations have been used to analyse microstructures of CdTe films grown on {112} surfaces of zinc-blende CdS. Interestingly, CdTe films grow in <331> orientations as opposed to <112> epitaxial orientations. At the CdTe-{331}/CdS-{112} interface, however, there exists an axis that is parallel to the <110> orientation of both CdS and CdTe. It is the direction orthogonal to this <110> that becomes different, being <116> for CdTe and <111> for CdS, respectively. Missing CdTe-{110} planes are found along the <110> axis, suggesting that the misfit strain is released by the conventional misfit dislocation mechanism along this axis. In themore » orthogonal axis, the misfit strain is found to be more effectively released by the new grain orientation mechanism. Our finding is supported by literature experimental observations of the change of growth direction when Cd 0.96Zn 0.04Te films are deposited on GaAs. Lastly the analyses of energetics clearly demonstrate the cause for the formation of the new orientation, and the insights gained from our studies can help understand the grain structures experimentally observed in lattice mismatched systems.« less

Understanding misfit strain releasing mechanisms via molecular dynamics simulations of CdTe growth on {112}zinc-blende CdS

DOE PAGES

Zhou, Xiaowang; Chavez, Jose J.; Almeida, Sergio F.; ...

2016-07-25

Molecular dynamics simulations have been used to analyse microstructures of CdTe films grown on {112} surfaces of zinc-blende CdS. Interestingly, CdTe films grow in <331> orientations as opposed to <112> epitaxial orientations. At the CdTe-{331}/CdS-{112} interface, however, there exists an axis that is parallel to the <110> orientation of both CdS and CdTe. It is the direction orthogonal to this <110> that becomes different, being <116> for CdTe and <111> for CdS, respectively. Missing CdTe-{110} planes are found along the <110> axis, suggesting that the misfit strain is released by the conventional misfit dislocation mechanism along this axis. In themore » orthogonal axis, the misfit strain is found to be more effectively released by the new grain orientation mechanism. Our finding is supported by literature experimental observations of the change of growth direction when Cd 0.96Zn 0.04Te films are deposited on GaAs. Lastly the analyses of energetics clearly demonstrate the cause for the formation of the new orientation, and the insights gained from our studies can help understand the grain structures experimentally observed in lattice mismatched systems.« less

Indications, limitations and pitfalls in the determination of human growth hormone, IGF-I and their binding proteins.

PubMed

Laron, Zvi; Bidlingmaier, Martin; Strasburger, Christian Joseph

2007-10-01

Deviations from normal growth are a major part of Pediatric Endocrinology. The principal post-natal growth promoting hormones are pituitary growth hormone (GH) and insulin-like growth factor-I (IGF-I). The GH-IGF-I axis has many links and portals, the secrets of which have been disclosed in recent years by scientific advances (genetic and biochemical technologies). In this article, we describe the players in the GH axis, the auxological indications for performing GH evaluation tests, enumerate the most frequently used tests and discuss the laboratory tests which help to define the pathological entities along the GH axis. Emphasis is put on the limitations of methods used, lack of standards, norms and the possible errors in diagnosis and treatment indications that may evolve. As both hGH and IGF-I immunoassay measurements represent cornerstones in the diagnosis and monitoring of the different etiological entities presenting with short stature, clinicians must have an insight into the variability and limitations of these analytical techniques. Interpretation of biochemical results without proper reference data and without knowledge of the assay-inherent characteristics inevitably leads to misdiagnosis, unnecessary further testing and treatment and imposes a burden on the child, family and the health care system.

Transverse plane of apical vertebra of structural thoracic curve: vertebra displacement versus vertebral deformation.

PubMed

Kotwicki, Tomasz; Napiontek, Marek; Nowakowski, Andrzej

2006-01-01

CT transversal scans of the trunk provided at the level of Th8 or Th9 (apical vertebra) of 23 patients with structural thoracic scoliosis were reviewed. The following parameters were studied: 1) alpha angle formed by the axis of vertebra and the axis of spinous process, 2) beta concave and beta convex angle between the spinous process and the left and right transverse process respectively, 3) gamma concave and gamma convex angle between the axis of vertebra and the left and right transverse process respectively, 4) rotation angle to the sagittal plane according to Aaro and Dahlborn, 5) Cobb angle. Values of measured parameters demonstrated a common pattern of intravertebral deformity: counter clockwise deviation of the spinous process (alpha angle 15,0 +/-8,5 degrees), beta concave (69,8 +/-8,5 degrees) significantly greater than beta convex (38,8 +/-8,5 degrees), gamma concave (54,3 +/-7,8 degrees) not different from gamma convex (56,0 +/-8,0 degrees). Strong linear positive correlation between alpha angle and Aaro-Dahlborn angle was observed (r=0,78, p<0,05). Changes in morphology of apical vertebra due to intravertebral bone remodelling followed the vertebral spatial displacement and there existed a linear correlation in between. The two processes develop in opposite directions.

[Corticotropic axis and chronic stress in abdominal obesity and metabolic syndrome].

PubMed

Boullu-Ciocca, S; Verger, P; Bocquier, A; Oliver, C

2005-12-03

Several indicators of corticotropic axis hyperactivity have been observed in common abdominal obesity, which is clinically similar to the obesity found in Cushing's syndrome. Corticotropic axis hyperactivity may be involved in the development and metabolic and cardiovascular complications of abdominal obesity. Several mechanisms may be responsible for this hormonal dysregulation: genetic, lifestyle, and nutritional factors, and chronic stress. We note the necessity of methodologically-impeccable clinical studies for an objective evaluation of the role of stress in obesity.

Analysis of graphic representation ability in oscillation phenomena

NASA Astrophysics Data System (ADS)

Dewi, A. R. C.; Putra, N. M. D.; Susilo

2018-03-01

This study aims to investigates how the ability of students to representation graphs of linear function and harmonic function in understanding of oscillation phenomena. Method of this research used mix methods with concurrent embedded design. The subjects were 35 students of class X MIA 3 SMA 1 Bae Kudus. Data collection through giving essays and interviews that lead to the ability to read and draw graphs in material of Hooke's law and oscillation characteristics. The results of study showed that most of the students had difficulty in drawing graph of linear function and harmonic function of deviation with time. Students’ difficulties in drawing the graph of linear function is the difficulty of analyzing the variable data needed in graph making, confusing the placement of variable data on the coordinate axis, the difficulty of determining the scale interval on each coordinate, and the variation of how to connect the dots forming the graph. Students’ difficulties in representing the graph of harmonic function is to determine the time interval of sine harmonic function, the difficulty to determine the initial deviation point of the drawing, the difficulty of finding the deviation equation of the case of oscillation characteristics and the confusion to different among the maximum deviation (amplitude) with the length of the spring caused the load.Complexity of the characteristic attributes of the oscillation phenomena graphs, students tend to show less well the ability of graphical representation of harmonic functions than the performance of the graphical representation of linear functions.

The human heart: application of the golden ratio and angle.

PubMed

Henein, Michael Y; Zhao, Ying; Nicoll, Rachel; Sun, Lin; Khir, Ashraf W; Franklin, Karl; Lindqvist, Per

2011-08-04

The golden ratio, or golden mean, of 1.618 is a proportion known since antiquity to be the most aesthetically pleasing and has been used repeatedly in art and architecture. Both the golden ratio and the allied golden angle of 137.5° have been found within the proportions and angles of the human body and plants. In the human heart we found many applications of the golden ratio and angle, in addition to those previously described. In healthy hearts, vertical and transverse dimensions accord with the golden ratio, irrespective of different absolute dimensions due to ethnicity. In mild heart failure, the ratio of 1.618 was maintained but in end-stage heart failure the ratio significantly reduced. Similarly, in healthy ventricles mitral annulus dimensions accorded with the golden ratio, while in dilated cardiomyopathy and mitral regurgitation patients the ratio had significantly reduced. In healthy patients, both the angles between the mid-luminal axes of the pulmonary trunk and the ascending aorta continuation and between the outflow tract axis and continuation of the inflow tract axis of the right ventricle approximate to the golden angle, although in severe pulmonary hypertension, the angle is significantly increased. Hence the overall cardiac and ventricular dimensions in a normal heart are consistent with the golden ratio and angle, representing optimum pump structure and function efficiency, whereas there is significant deviation in the disease state. These findings could have anatomical, functional and prognostic value as markers of early deviation from normality. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Comparative analysis of 2D and 3D distance measurements to study spatial genome organization.

PubMed

Finn, Elizabeth H; Pegoraro, Gianluca; Shachar, Sigal; Misteli, Tom

2017-07-01

The spatial organization of genomes is non-random, cell-type specific, and has been linked to cellular function. The investigation of spatial organization has traditionally relied extensively on fluorescence microscopy. The validity of the imaging methods used to probe spatial genome organization often depends on the accuracy and precision of distance measurements. Imaging-based measurements may either use 2 dimensional datasets or 3D datasets which include the z-axis information in image stacks. Here we compare the suitability of 2D vs 3D distance measurements in the analysis of various features of spatial genome organization. We find in general good agreement between 2D and 3D analysis with higher convergence of measurements as the interrogated distance increases, especially in flat cells. Overall, 3D distance measurements are more accurate than 2D distances, but are also more susceptible to noise. In particular, z-stacks are prone to error due to imaging properties such as limited resolution along the z-axis and optical aberrations, and we also find significant deviations from unimodal distance distributions caused by low sampling frequency in z. These deviations are ameliorated by significantly higher sampling frequency in the z-direction. We conclude that 2D distances are preferred for comparative analyses between cells, but 3D distances are preferred when comparing to theoretical models in large samples of cells. In general and for practical purposes, 2D distance measurements are preferable for many applications of analysis of spatial genome organization. Published by Elsevier Inc.

Caudal Septal Stabilization Suturing Technique to Treat Crooked Noses.

PubMed

Baykal, Bahadir; Erdim, Ibrahim; Guvey, Ali; Oghan, Fatih; Kayhan, Fatma Tulin

2016-10-01

To rotate the nasal axis and septum to the midline using an L-strut graft and a novel caudal septal stabilization suturing technique to treat crooked noses. Thirty-six patients were included in the study. First, an L-strut graft was prepared by excising the deviated cartilage site in all patients. Second, multiple stabilization suturing, which we describe as a caudal septal stabilization suturing technique with a "fishing net"-like appearance, was applied between the anterior nasal spine and caudal septum in all patients. This new surgical technique, used to rotate the caudal septum, was applied to 22 I-type and 14 C-type crooked noses. Correction rates for the crooked noses were compared between the 2 inclination types with angular estimations. Deviation angles were measured using the AutoCAD 2012 software package and frontal (anterior) views, with the Frankfurt horizontal line parallel to the ground. Nasal axis angles showing angle improvement graded 4 categories as excellent, good, acceptable, and unsuccessful for evaluations at 6 months after surgery in the study. The success rate in the C-type nasal inclination was 86.7% (±21.9) and 88% (±16.7) in the I-type. The overall success rate of L-strut grafting and caudal septal stabilization suturing in crooked nose surgeries was 87.5% (±18.6). "Unsuccessful" results were not reported in any of the patients. L-strut grafting and caudal septal stabilization suturing techniques are efficacious in crooked noses according to objective measurement analysis results. However, a longer follow-up duration in a larger patient population is needed.

Evaluation of different approaches to modeling the second-order ionospheric delay on GPS measurements

NASA Astrophysics Data System (ADS)

Garcia-Fernandez, M.; Desai, S. D.; Butala, M. D.; Komjathy, A.

2013-12-01

This work evaluates various approaches to compute the second order ionospheric correction (SOIC) to Global Positioning System (GPS) measurements. When estimating the reference frame using GPS, applying this correction is known to primarily affect the realization of the origin of the Earth's reference frame along the spin axis (Z coordinate). Therefore, the Z translation relative to the International Terrestrial Reference Frame 2008 is used as the metric to evaluate various published approaches to determining the slant total electron content (TEC) for the SOIC: getting the slant TEC from GPS measurements, and using the vertical total electron content (TEC) given by a Global Ionospheric Model (GIM) to transform it to slant TEC via a mapping function. All of these approaches agree to 1 mm if the ionospheric shell height needed in GIM-based approaches is set to 600 km. The commonly used shell height of 450 km introduces an offset of 1 to 2 mm. When the SOIC is not applied, the Z axis translation can be reasonably modeled with a ratio of +0.23 mm/TEC units of the daily median GIM vertical TEC. Also, precise point positioning (PPP) solutions (positions and clocks) determined with and without SOIC differ by less than 1 mm only if they are based upon GPS orbit and clock solutions that have consistently applied or not applied the correction, respectively. Otherwise, deviations of few millimeters in the north component of the PPP solutions can arise due to inconsistencies with the satellite orbit and clock products, and those deviations exhibit a dependency on solar cycle conditions.

The Attitude Control System for the Wilkinson Microwave Anisotropy Probe

NASA Technical Reports Server (NTRS)

Markley, F. Landis; Andrews, Stephen F.; ODonnell, James R., Jr.; Ward, David K.

2003-01-01

The Wilkinson Microwave Anisotropy Probe mission produces a map of the cosmic microwave background radiation over the entire celestial sphere by executing a fast spin and a slow precession of its spin axis about the Sun line to obtain a highly interconnected set of measurements. The spacecraft attitude is sensed and controlled using an inertial reference unit, two star trackers, a digital sun sensor, twelve coarse sun sensors, three reaction wheel assemblies, and a propulsion system. Sufficient attitude knowledge is provided to yield instrument pointing to a standard deviation (l sigma) of 1.3 arc-minutes per axis. In addition, the spacecraft acquires and holds the sunline at initial acquisition and in the event of a failure, and slews to the proper orbit adjust orientations and to the proper off-sunline attitude to start the compound spin. This paper presents an overview of the design of the attitude control system to carry out this mission and presents some early flight experience.

Analysis on detection accuracy of binocular photoelectric instrument optical axis parallelism digital calibration instrument

NASA Astrophysics Data System (ADS)

Ying, Jia-ju; Yin, Jian-ling; Wu, Dong-sheng; Liu, Jie; Chen, Yu-dan

2017-11-01

Low-light level night vision device and thermal infrared imaging binocular photoelectric instrument are used widely. The maladjustment of binocular instrument ocular axises parallelism will cause the observer the symptom such as dizziness, nausea, when use for a long time. Binocular photoelectric equipment digital calibration instrument is developed for detecting ocular axises parallelism. And the quantitative value of optical axis deviation can be quantitatively measured. As a testing instrument, the precision must be much higher than the standard of test instrument. Analyzes the factors that influence the accuracy of detection. Factors exist in each testing process link which affect the precision of the detecting instrument. They can be divided into two categories, one category is factors which directly affect the position of reticle image, the other category is factors which affect the calculation the center of reticle image. And the Synthesize error is calculated out. And further distribute the errors reasonably to ensure the accuracy of calibration instruments.

Contrast-enhanced multidetector computerized tomography for odontogenic cysts and cystic-appearing tumors of the jaws: is it useful?

PubMed

Kakimoto, Naoya; Chindasombatjaroen, Jira; Tomita, Seiki; Shimamoto, Hiroaki; Uchiyama, Yuka; Hasegawa, Yoko; Kishino, Mitsunobu; Murakami, Shumei; Furukawa, Souhei

2013-01-01

The purpose of this study was to investigate the usefulness of computerized tomography (CT), particularly contrast-enhanced CT, in differentiation of jaw cysts and cystic-appearing tumors. We retrospectively analyzed contrast-enhanced CT images of 90 patients with odontogenic jaw cysts or cystic-appearing tumors. The lesion size and CT values were measured and the short axis to long axis (S/L) ratio, contrast enhancement (CE) ratio, and standard deviation ratio were calculated. The lesion size and the S/L ratio of keratocystic odontogenic tumors were significantly different from those of radicular cysts and follicular cysts. There were no significant differences in the CE ratio among the lesions. Multidetector CT provided diagnostic information about the size of odontogenic cysts and cystic-appearing tumors of the jaws that was related to the lesion type, but showed no relation between CE ratio and the type of these lesions. Copyright © 2013 Elsevier Inc. All rights reserved.

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

Karabourniotis, D.; Couris, S.; Damelincourt, J.J.

The partial pressure of thallium in high-pressure Hg-TlI discharges with different mercury, thallium, and electron pressures has been measured by using the optically thin line Tl 655 nm and the self-reversed line Tl 535 nm. The partial pressure of the arc axis has been measured from the line Tl 655nm. The effective partial pressure has been measured from the self-reversed line Tl 535 nm on the basis of the multiparameter method, and it has been calculated from the known axis pressure of thallium and the calculation of its radial variation by taking into account the chemical reactions. The experimental resultsmore » confirm the dispersion character of the blue wing of the line Tl 535 nm. The systematic difference obtained between the measured and calculated effective pressure, particularly at the moment of minimum electron density, may be interpreted by deviations from the local thermodynamic equilibrium (LTE) caused by overpopulation of the upper level of the line Tl 535 nm.« less

Band Gap Optimization Design of Photonic Crystals Material

NASA Astrophysics Data System (ADS)

Yu, Y.; Yu, B.; Gao, X.

2017-12-01

The photonic crystal has a fundamental characteristic - photonic band gap, which can prevent light to spread in the crystals. This paper studies the width variation of band gaps of two-dimension square lattice photonic crystals by changing the geometrical shape of the unit cells’ inner medium column. Using the finite element method, we conduct numerical experiments on MATLAB 2012a and COMSOL 3.5. By shortening the radius in vertical axis and rotating the medium column, we design a new unit cell, with a 0.3*3.85e-7 vertical radius and a 15 degree deviation to the horizontal axis. The new cell has a gap 1.51 percent wider than the circle medium structure in TE gap and creates a 0.0124 wide TM gap. Besides, the experiment shows the first TM gap is partially overlapped by the second TE gap in gap pictures. This is helpful to format the absolute photonic band gaps and provides favorable theoretical basis for designing photonic communication material.

Evolution of space open electric arc burning in the external axial magnetic field

NASA Astrophysics Data System (ADS)

Urusova, I. R.; Urusova, T. E.

2018-06-01

The calculation was made for open DC electric arc burning in an external uniform axial magnetic field. It was performed within the framework of a nonstationary three-dimensional mathematical model in approximation of partial local thermodynamic equilibrium of plasma. A "schematic" analog of electron temperature fluctuations was proposed for numerical realization of the open electric arc column of a helical shape. According to calculations, it was established that the column of the open electric arc takes a helical space shape. Plasma rotates around a longitudinal axis of the arc, at that the directions of plasma rotation near the cathode and the anode are opposite. In the arc cross-sections, the velocity of plasma rotation is unequal and the deviation value of the same part of the arc from the central axis varies in time. A helical shape of the open arc is not stable and varies in time. Apparently, the open arc cannot remain stable and invariable in the time helical shape in the external axial magnetic field.

The low-degree shape of Mercury

NASA Astrophysics Data System (ADS)

Perry, Mark E.; Neumann, Gregory A.; Phillips, Roger J.; Barnouin, Olivier S.; Ernst, Carolyn M.; Kahan, Daniel S.; Solomon, Sean C.; Zuber, Maria T.; Smith, David E.; Hauck, Steven A.; Peale, Stanton J.; Margot, Jean-Luc; Mazarico, Erwan; Johnson, Catherine L.; Gaskell, Robert W.; Roberts, James H.; McNutt, Ralph L.; Oberst, Juergen

2015-09-01

The shape of Mercury, particularly when combined with its geoid, provides clues to the planet's internal structure, thermal evolution, and rotational history. Elevation measurements of the northern hemisphere acquired by the Mercury Laser Altimeter on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft, combined with 378 occultations of radio signals from the spacecraft in the planet's southern hemisphere, reveal the low-degree shape of Mercury. Mercury's mean radius is 2439.36 ± 0.02 km, and there is a 0.14 km offset between the planet's centers of mass and figure. Mercury is oblate, with a polar radius 1.65 km less than the mean equatorial radius. The difference between the semimajor and semiminor equatorial axes is 1.25 km, with the long axis oriented 15° west of Mercury's dynamically defined principal axis. Mercury's geoid is also oblate and elongated, but it deviates from a sphere by a factor of 10 less than Mercury's shape, implying compensation of elevation variations on a global scale.

Electrodeposition of ZnO nanorod arrays on ZnO substrate with tunable orientation and optical properties.

PubMed

Jehl, Z; Rousset, J; Donsanti, F; Renou, G; Naghavi, N; Lincot, D

2010-10-01

The electrodeposition of ZnO nanorods on ZnO:Al films with different orientations is reported. The influence of the total charge exchanged during electrodeposition on the nanorod's geometry (length, diameter, aspect ratio and surface density) and the optical transmission properties of the nanorod arrays is studied on a [0001]-oriented ZnO:Al substrate. The nanorods are highly vertically oriented along the c axis, following the lattice matching with the substrate. The growth on a [1010] and [1120] ZnO:Al-oriented substrate with c axis parallel to the substrate leads to a systematic deviation angle of 55 degrees from the perpendicular direction. This finding has been explained by the occurrence of a minority orientation with the [1011] planes parallel to the surface, with a preferential growth on corresponding [0001] termination. Substrate crystalline orientation is thereby found to be a major parameter in finely tuning the orientation of the nanorod array. This new approach allows us to optimize the light scattering properties of the films.

Seismicity During Continental Breakup in the Red Sea Rift of Northern Afar

NASA Astrophysics Data System (ADS)

Illsley-Kemp, Finnigan; Keir, Derek; Bull, Jonathan M.; Gernon, Thomas M.; Ebinger, Cynthia; Ayele, Atalay; Hammond, James O. S.; Kendall, J.-Michael; Goitom, Berhe; Belachew, Manahloh

2018-03-01

Continental rifting is a fundamental component of plate tectonics. Recent studies have highlighted the importance of magmatic activity in accommodating extension during late-stage rifting, yet the mechanisms by which crustal thinning occurs are less clear. The Red Sea rift in Northern Afar presents an opportunity to study the final stages of continental rifting as these active processes are exposed subaerially. Between February 2011 and February 2013 two seismic networks were installed in Ethiopia and Eritrea. We locate 4,951 earthquakes, classify them by frequency content, and calculate 31 focal mechanisms. Results show that seismicity is focused at the rift axis and the western marginal graben. Rift axis seismicity accounts for ˜64% of the seismic moment release and exhibits a swarm-like behavior. In contrast, seismicity at the marginal graben is characterized by high-frequency earthquakes that occur at a constant rate. Results suggest that the rift axis remains the primary locus of seismicity. Low-frequency earthquakes, indicative of magmatic activity, highlight the presence of a magma complex ˜12 km beneath Alu-Dalafilla at the rift axis. Seismicity at the marginal graben predominantly occurs on westward dipping, antithetic faults. Focal mechanisms show that this seismicity is accommodating E-W extension. We suggest that the seismic activity at the marginal graben is either caused by upper crustal faulting accommodating enhanced crustal thinning beneath Northern Afar or as a result of flexural faulting between the rift and plateau. This seismicity is occurring in conjunction with magmatic extension at the rift axis, which accommodates the majority of long-term extension.

Spectral sensitivity of cones of the monkey Macaca fascicularis.

PubMed Central

Baylor, D A; Nunn, B J; Schnapf, J L

1987-01-01

1. Spectral sensitivities of cones in the retina of cynomolgus monkeys were determined by recording photocurrents from single outer segments with a suction electrode. 2. The amplitude and shape of the response to a flash depended upon the number of photons absorbed but not the wave-length, so that the 'Principle of Univariance' was obeyed. 3. Spectra were obtained from five 'blue', twenty 'green', and sixteen 'red' cones. The wave-lengths of maximum sensitivity were approximately 430, 531 and 561 nm, respectively. 4. The spectra of the three types of cones had similar shapes when plotted on a log wave number scale, and were fitted by an empirical expression. 5. There was no evidence for the existence of subclasses of cones with different spectral sensitivities. Within a class, the positions of the individual spectra on the wave-length axis showed a standard deviation of less than 1.5 nm. 6. Psychophysical results on human colour matching (Stiles & Burch, 1955; Stiles & Burch, 1959) were well predicted from the spectral sensitivities of the monkey cones. After correction for pre-retinal absorption and pigment self-screening, the spectra of the red and green cones matched the respective pi 5 and pi 4 mechanisms of Stiles (1953, 1959). PMID:3443931

Effect of flattened surface morphology of anodized aluminum oxide templates on the magnetic properties of nanoporous Co/Pt and Co/Pd thin multilayered films

NASA Astrophysics Data System (ADS)

Nguyen, T. N. Anh; Fedotova, J.; Kasiuk, J.; Bayev, V.; Kupreeva, O.; Lazarouk, S.; Manh, D. H.; Vu, D. L.; Chung, S.; Åkerman, J.; Altynov, V.; Maximenko, A.

2018-01-01

For the first time, nanoporous Al2O3 templates with smoothed surface relief characterized by flattened interpore areas were used in the fabrication of Co/Pd and Co/Pt multilayers (MLs) with strong perpendicular magnetic anisotropy (PMA). Alternating gradient magnetometry (AGM) revealed perfectly conserved PMA in the Co/Pd and Co/Pt porous MLs (antidot arrays) with a ratio of remanent magnetization (Mr) to saturation magnetization (MS) of about 0.99, anisotropy fields (Ha) of up to 2.6 kOe, and a small deviation angle of 8° between the easy magnetization axis and the normal to the film surface. The sufficient magnetic hardening of the porous MLs with enhanced coercive field HC of up to ∼1.9 kOe for Co/Pd and ∼1.5 kOe for Co/Pt MLs, as compared to the continuous reference samples (∼1.5-2 times), is associated with the pinning of the magnetic moments on the nanopore edges. Application of the Stoner-Wohlfarth model for fitting the experimental M/MS(H) curves yielded clear evidence of the predominantly coherent rotation mechanism of magnetization reversal in the porous films.

Initial experience with custom-fit total knee replacement: intra-operative events and long-leg coronal alignment.

PubMed

Spencer, Brian A; Mont, Michael A; McGrath, Mike S; Boyd, Bradley; Mitrick, Michael F

2009-12-01

New technology using magnetic resonance imaging (MRI) allows the surgeon to place total knee replacement components into each patient's pre-arthritic natural alignment. This study evaluated the initial intra-operative experience using this technique. Twenty-one patients had a sagittal MRI of their arthritic knee to determine component placement for a total knee replacement. Cutting guides were machined to control all intra-operative cuts. Intra-operative events were recorded and these knees were compared to a matching cohort of the senior surgeon's previous 30 conventional total knee replacements. Post-operative scanograms were obtained from each patient and coronal alignment was compared to previous studies using conventional and computer-assisted techniques. There were no intra-operative or acute post-operative complications. There were no differences in blood loss and there was a mean decrease in operative time of 14% compared to a cohort of patients with conventional knee replacements. The average deviation from the mechanical axis was 1.2 degrees of varus, which was comparable to previously reported conventional and computer-assisted techniques. Custom-fit total knee replacement appeared to be a safe procedure for uncomplicated cases of osteoarthritis.

The Changes They are A-Timed: Metabolism, Endogenous Clocks, and the Timing of Puberty

PubMed Central

Tolson, Kristen P.; Chappell, Patrick E.

2012-01-01

Childhood obesity has increased dramatically over the last several decades, particularly in industrialized countries, often accompanied by acceleration of pubertal progression and associated reproductive abnormalities (Biro et al., 2006; Rosenfield et al., 2009). The timing of pubertal initiation and progression in mammals is likely influenced by nutritional and metabolic state, leading to the hypothesis that deviations from normal metabolic rate, such as those seen in obesity, may contribute to observed alterations in the rate of pubertal progression. While several recent reviews have addressed the effects of metabolic disorders on reproductive function in general, this review will explore previous and current models of pubertal timing, outlining a potential role of endogenous timing mechanisms such as cellular circadian clocks in the initiation of puberty, and how these clocks might be altered by metabolic factors. Additionally, we will examine recently elucidated neuroendocrine regulators of pubertal progression such as kisspeptin, explore models detailing how the mammalian reproductive axis is silenced during the juvenile period and reactivated at appropriate developmental times, and emphasize how metabolic dysfunction such as childhood obesity may alter timing cues that advance or delay pubertal progression, resulting in diminished reproductive capacity. PMID:22645521

Dual-mode disturbance-accommodating pointing controller for Hubble Space Telescope

NASA Astrophysics Data System (ADS)

Addington, Stewart I.; Johnson, C. D.

1995-03-01

Cyclic thermal expansions and mechanical stiction effects in the solar arrays on the Hubble Space Telescope (HST) are triggering repeated occurrences of damped, relaxation-type flex-body vibrations of the solar arrays. Those solar array vibrations are, in turn, causing unwanted deviations of the telescope from its specified pointing direction. In this paper we propose two strategies one can adopt in designing a telescope-pointing controller to cope with the aforementioned disturbances: 1) a total isolation (TI) control strategy whereby the HST controller torques are designed to adaptively counteract and cancel out the persistent disturbing torques that are causing the unwanted telescope motions and 2) an array damping (AD) control strategy whereby the HST controller torques are used to actively augment the natural dampening of the solar array vibrations and the attendant telescope motions, between triggerings of the stiction-related flex-body relaxation oscillations. Using the principles of disturbance accommodation control theory, a dual-mode controller for a generic, planar-motion (single-axis) model of the HST is proposed. This controller incorporates both the TI and AD modes of disturbance accommodation. Simulation studies of the closed-loop system using generic parameter values clearly indicate, qualitatively, the enhanced pointing performance such a controller can achieve.

Femoral Reconstruction Using External Fixation

PubMed Central

Palatnik, Yevgeniy; Rozbruch, S. Robert

2011-01-01

Background. The use of an external fixator for the purpose of distraction osteogenesis has been applied to a wide range of orthopedic problems caused by such diverse etiologies as congenital disease, metabolic conditions, infections, traumatic injuries, and congenital short stature. The purpose of this study was to analyze our experience of utilizing this method in patients undergoing a variety of orthopedic procedures of the femur. Methods. We retrospectively reviewed our experience of using external fixation for femoral reconstruction. Three subgroups were defined based on the primary reconstruction goal lengthening, deformity correction, and repair of nonunion/bone defect. Factors such as leg length discrepancy (LLD), limb alignment, and external fixation time and complications were evaluated for the entire group and the 3 subgroups. Results. There was substantial improvement in the overall LLD, femoral length discrepancy, and limb alignment as measured by mechanical axis deviation (MAD) and lateral distal femoral angle (LDFA) for the entire group as well as the subgroups. Conclusions. The Ilizarov external fixator allows for decreased surgical exposure and preservation of blood supply to bone, avoidance of bone grafting and internal fixation, and simultaneous lengthening and deformity correction, making it a very useful technique for femoral reconstruction. PMID:21991425

The virtual isocentric aiming device: a new mechanical targeting concept.

PubMed

Mendel, Thomas; Hänni, Markus; Gueorguiev, Boyko; Wohlrab, David; Hofmann, Gunther Olaf

2011-12-01

Minimally invasive fracture fixation can be technically demanding, especially in body regions characterised by complex bone anatomy and the presence of a significant amount of soft tissue. Hence, this procedure is associated with a high risk of implant malposition. As a consequence, radiation exposure to the patient and the surgeon increases within surgery. The purpose of this study was to evaluate the practicability and accuracy of a newly designed virtual isocentric aiming device (VIAD) as compared to the more traditional approach of the freehand insertion of K-wires. Forty polyurethane foam blocks were prepared with a reference wire (W ( R )) and covered by sponge material to simulate soft tissue. For the sake of comparison, both an untrained and an experienced surgeon were selected for the study and were advised to insert a K-wire into the foam block so as to have the same axis as the W ( R ) using both of the aforementioned methods. The clinical parameters of both techniques were analysed. In addition, 3-D precision data computed using CT-scans of each sample were evaluated. Device adjustment prolonged the time required for the experienced surgeon to complete the VIAD procedure when compared to the freehand method. However, using the VIAD, the number of plane changes made to the image intensifier in addition to the number of drill trials was significantly reduced by each surgeon. Furthermore, mechanical K-wire navigation leads to a decrease in the radiation exposure time for the untrained surgeon. VIAD-guided K-wires revealed a significant lower angle of deviation in relation to W ( R ). Tip-to-tip and tip-to-axis distances displayed a trend indicating reduced displacement values as well. The VIAD allows for simple wire insertion with increased precision as well as a reduction in radiation exposure, plane changes of the image intensifier and the number of drill trials compared to the freehand method. The VIAD also satisfies the demand for a less invasive technique. Prospectively, the VIAD represents a useful and cost-effective alternative to the freehand method.

Integrated mechanics for the passive damping of polymer-matrix composites and composite structures

NASA Technical Reports Server (NTRS)

Saravanos, D. A.; Chamis, Christos C.

1991-01-01

Some recent developments on integrated damping mechanics for unidirectional composites, laminates, and composite structures are reviewed. Simplified damping micromechanics relate the damping of on-axis and off-axis composites to constituent properties, fiber volume ratio, fiber orientation, temperature, and moisture. Laminate and structural damping mechanics for thin composites are summarized. Discrete layer damping mechanics for thick laminates, including the effects of interlaminar shear damping, are developed and semianalytical predictions of modal damping in thick simply supported specialty composite plates are presented. Applications show the advantages of the unified mechanics, and illustrate the effect of fiber volume ratio, fiber orientation, structural geometry, and temperature on the damping. Additional damping properties for composite plates of various laminations, aspect ratios, fiber content, and temperature illustrate the merits and ranges of applicability of each theory (thin or thick laminates).

Renal sympathetic denervation inhibits the development of left ventricular mechanical dyssynchrony during the progression of heart failure in dogs.

PubMed

Hu, Wei; Zhao, Qing-yan; Yu, Sheng-bo; Sun, Bin; Chen, Liao; Cao, Sheng; Guo, Rui-qiang

2014-11-22

The purpose of this study was to investigate whether transcatheter renal sympathetic denervation (RSD) interfere with the development of left ventricular (LV) mechanical dyssynchrony during the progression of heart failure (HF). Nineteen beagles were randomly divided into sham-operated group (six dogs), control group (seven dogs), and RSD group (six dogs). Sham-operated group were implanted with pacemakers without pacing; Control group were implanted with pacemakers and underwent 3 weeks of rapid right ventricular pacing; and RSD group underwent catheter-based RSD bilaterally and were simultaneously implanted with pacemakers. Both LV strain and LV dyssynchrony were analyzed via 2D speckle-tracking strain echocardiography to evaluate LV function. Longitudinal dyssynchrony was determined as the standard deviation for time-to-peak speckle-tracking strain on apical 4- and 2-chamber views. Radial and circumferential dyssynchrony was determined as the standard deviation for time-to-peak speckle-tracking strain in mid- and base-LV short-axis views. Each myocardial function was also evaluated by averaging the peak systolic strains. LV systolic pressure (LVSP) and LV end-diastolic pressure (LVEDP) were measured. The LV interstitial fibrosis was determined by histological analysis. Plasma angiotensin II (Ang II), aldosterone and norepinephrine (NE) levels were also measured. After 3 weeks, all of the dogs in both the control and RSD groups showed greater LV end-diastolic volume compared with the sham-operated group; however, the dogs in the RSD group had a higher LV ejection fraction (LVEF) than the dogs in the control group (p<0.001). The LV systolic strains were higher in the RSD group than in the control group (p<0.001 for longitudinal, circumferential and radial strain, respectively). The levels of LV dyssynchrony were lower in the RSD group than in the control group (p<0.001 for longitudinal, circumferential and radial dyssynchrony, respectively). Compared with dogs with control alone, RSD dogs had lower LV end-diastolic pressures and less fibrous tissue. The levels of plasma Ang II, aldosterone and NE were lower in the RSD group than in the control group. RSD inhibites the development of left ventricular mechanical dyssynchrony during the progression of heart failure in dogs.

Rotatable multifunctional load frames for neutron diffractometers at FRM II—design, specifications and applications

NASA Astrophysics Data System (ADS)

Hoelzel, M.; Gan, W. M.; Hofmann, M.; Randau, C.; Seidl, G.; Jüttner, Ph.; Schmahl, W. W.

2013-05-01

Novel tensile rigs have been designed and manufactured at the research reactor Heinz Maier-Leibnitz (FRM II, Garching near Munich). Besides tensile and compressive stress, also torsion can be applied. The unique Eulerian cradle type design (ω, χ, and φ axis) allows orienting the stress axis with respect to the scattering vector. Applications of these tensile rigs at our neutron diffractometers enable various investigations of structural changes under mechanical load, e.g. crystallographic texture evolution, stress-induced phase transformations or lattice expansion, and the anisotropy of mechanical response.

Upper intestinal lipids regulate energy and glucose homeostasis.

PubMed

Cheung, Grace W C; Kokorovic, Andrea; Lam, Tony K T

2009-09-01

Upon the entry of nutrients into the small intestine, nutrient sensing mechanisms are activated to allow the body to adapt appropriately to the incoming nutrients. To date, mounting evidence points to the existence of an upper intestinal lipid-induced gut-brain neuronal axis to regulate energy homeostasis. Moreover, a recent discovery has also revealed an upper intestinal lipid-induced gut-brain-liver neuronal axis involved in the regulation of glucose homeostasis. In this mini-review, we will focus on the mechanisms underlying the activation of these respective neuronal axes by upper intestinal lipids.

Piezoelectric particle accelerator

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

Kemp, Mark A.; Jongewaard, Erik N.; Haase, Andrew A.

2017-08-29

A particle accelerator is provided that includes a piezoelectric accelerator element, where the piezoelectric accelerator element includes a hollow cylindrical shape, and an input transducer, where the input transducer is disposed to provide an input signal to the piezoelectric accelerator element, where the input signal induces a mechanical excitation of the piezoelectric accelerator element, where the mechanical excitation is capable of generating a piezoelectric electric field proximal to an axis of the cylindrical shape, where the piezoelectric accelerator is configured to accelerate a charged particle longitudinally along the axis of the cylindrical shape according to the piezoelectric electric field.

Brain-derived neurotrophic factor and hypothalamic-pituitary-adrenal axis adaptation processes in a depressive-like state induced by chronic restraint stress.

PubMed

Naert, Gaelle; Ixart, Guy; Maurice, Tangui; Tapia-Arancibia, Lucia; Givalois, Laurent

2011-01-01

Depression is potentially life-threatening. The most important neuroendocrine abnormality in this disorder is hypothalamo-pituitary-adrenocortical (HPA) axis hyperactivity. Recent findings suggest that all depression treatments may boost the neurotrophin production especially brain-derived neurotrophic factor (BDNF). Moreover, BDNF is highly involved in the regulation of HPA axis activity. The aim of this study was to determine the impact of chronic stress (restraint 3h/day for 3 weeks) on animal behavior and HPA axis activity in parallel with hippocampus, hypothalamus and pituitary BDNF levels. Chronic stress induced changes in anxiety (light/dark box test) and anhedonic states (sucrose preference test) and in depressive-like behavior (forced swimming test); general locomotor activity and body temperature were modified and animal body weight gain was reduced by 17%. HPA axis activity was highly modified by chronic stress, since basal levels of mRNA and peptide hypothalamic contents in CRH and AVP and plasma concentrations in ACTH and corticosterone were significantly increased. The HPA axis response to novel acute stress was also modified in chronically stressed rats, suggesting adaptive mechanisms. Basal BDNF contents were increased in the hippocampus, hypothalamus and pituitary in chronically stressed rats and the BDNF response to novel acute stress was also modified. This multiparametric study showed that chronic restraint stress induced a depressive-like state that was sustained by mechanisms associated with BDNF regulation. Copyright © 2010 Elsevier Inc. All rights reserved.

Mechanical design optimization of a single-axis MOEMS accelerometer based on a grating interferometry cavity for ultrahigh sensitivity

NASA Astrophysics Data System (ADS)

Lu, Qianbo; Bai, Jian; Wang, Kaiwei; Lou, Shuqi; Jiao, Xufen; Han, Dandan; Yang, Guoguang

2016-08-01

The ultrahigh static displacement-acceleration sensitivity of a mechanical sensing chip is essential primarily for an ultrasensitive accelerometer. In this paper, an optimal design to implement to a single-axis MOEMS accelerometer consisting of a grating interferometry cavity and a micromachined sensing chip is presented. The micromachined sensing chip is composed of a proof mass along with its mechanical cantilever suspension and substrate. The dimensional parameters of the sensing chip, including the length, width, thickness and position of the cantilevers are evaluated and optimized both analytically and by finite-element-method (FEM) simulation to yield an unprecedented acceleration-displacement sensitivity. Compared with one of the most sensitive single-axis MOEMS accelerometers reported in the literature, the optimal mechanical design can yield a profound sensitivity improvement with an equal footprint area, specifically, 200% improvement in displacement-acceleration sensitivity with moderate resonant frequency and dynamic range. The modified design was microfabricated, packaged with the grating interferometry cavity and tested. The experimental results demonstrate that the MOEMS accelerometer with modified design can achieve the acceleration-displacement sensitivity of about 150μm/g and acceleration sensitivity of greater than 1500V/g, which validates the effectiveness of the optimal design.

Solar drum positioner mechanisms

NASA Technical Reports Server (NTRS)

Briggs, L. W.

1982-01-01

The need for additional power on spinning satellites required development of deployable solar arrays activated, as on a 3-axis vehicle, after separation from a booster or shuttle orbiter. Mechanisms were developed for telescopically extending a secondary 36.3 kg (80 lb.), 2.13 m (84 in.) diameter spinning solar drum for a distance of 2.0 m (80 in.) or more along the spin axis. After extension, the system has the capability of dynamically controlling the drum tilt angle about the spin axis to provide precision in-orbit balancing of the spacecraft. This approach was selected for the SBS, ANIK C, ANIK D, WESTAR B and PALAPA B satellites. It was successfully demonstrated during the in orbit deployment of the aft solar panels of the SBS F-3 and F-1 satellites, subsequent to the November 1980 and September 1981 launches.

SU-F-T-476: Performance of the AS1200 EPID for Periodic Photon Quality Assurance

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

DeMarco, J; Fraass, B; Yang, W

2016-06-15

Purpose: To assess the dosimetric performance of a new amorphous silicon flat-panel electronic portal imaging device (EPID) suitable for high-intensity, flattening-filter-free delivery mode. Methods: An EPID-based QA suite was created with automation to periodically monitor photon central-axis output and two-dimensional beam profile constancy as a function of gantry angle and dose-rate. A Varian TrueBeamTM linear accelerator installed with Developer Mode was used to customize and deliver XML script routines for the QA suite using the dosimetry mode image acquisition for an aS1200 EPID. Automatic post-processing software was developed to analyze the resulting DICOM images. Results: The EPID was used tomore » monitor photon beam output constancy (central-axis), flatness, and symmetry over a period of 10 months for four photon beam energies (6x, 15x, 6xFFF, and 10xFFF). EPID results were consistent to those measured with a standard daily QA check device. At the four cardinal gantry angles, the standard deviation of the EPID central-axis output was <0.5%. Likewise, EPID measurements were independent for the wide range of dose rates (including up to 2400 mu/min for 10xFFF) studied with a standard deviation of <0.8% relative to the nominal dose rate for each energy. Also, profile constancy and field size measurements showed good agreement with the reference acquisition of 0° gantry angle and nominal dose rate. XML script files were also tested for MU linearity and picket-fence delivery. Using Developer Mode, the test suite was delivered in <60 minutes for all 4 photon energies with 4 dose rates per energy and 5 picket-fence acquisitions. Conclusion: Dosimetry image acquisition using a new EPID was found to be accurate for standard and high-intensity photon beams over a broad range of dose rates over 10 months. Developer Mode provided an efficient platform to customize the EPID acquisitions by using custom script files which significantly reduced the time. This work was funded in part by Varian Medical Systems.« less

SU-F-J-25: Position Monitoring for Intracranial SRS Using BrainLAB ExacTrac Snap Verification

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

Jang, S; McCaw, T; Huq, M

2016-06-15

Purpose: To determine the accuracy of position monitoring with BrainLAB ExacTrac snap verification following couch rotations during intracranial SRS. Methods: A CT scan of an anthropomorphic head phantom was acquired using 1.25mm slices. The isocenter was positioned near the centroid of the frontal lobe. The head phantom was initially aligned on the treatment couch using cone-beam CT, then repositioned using ExacTrac x-ray verification with residual errors less than 0.2mm and 0.2°. Snap verification was performed over the full range of couch angles in 15° increments with known positioning offsets of 0–3mm applied to the phantom along each axis. At eachmore » couch angle, the smallest tolerance was determined for which no positioning deviation was detected. Results: For couch angles 30°–60° from the center position, where the longitudinal axis of the phantom is approximately aligned with the beam axis of one x-ray tube, snap verification consistently detected positioning errors exceeding the maximum 8mm tolerance. Defining localization error as the difference between the known offset and the minimum tolerance for which no deviation was detected, the RMS error is mostly less than 1mm outside of couch angles 30°–60° from the central couch position. Given separate measurements of patient position from the two imagers, whether to proceed with treatment can be determined by the criterion of a reading within tolerance from just one (OR criterion) or both (AND criterion) imagers. Using a positioning tolerance of 1.5mm, snap verification has sensitivity and specificity of 94% and 75%, respectively, with the AND criterion, and 67% and 93%, respectively, with the OR criterion. If readings exceeding maximum tolerance are excluded, the sensitivity and specificity are 88% and 86%, respectively, with the AND criterion. Conclusion: With a positioning tolerance of 1.5mm, ExacTrac snap verification can be used during intracranial SRS with sensitivity and specificity between 85% and 90%.« less

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

MacKay,W.W.

For a ring like RHIC with two full Siberian snakes on opposite sides of the ring, the spin tune for a flat orbit will be 1/2 if the snake rotation axes are perpendicular, {Delta}{phi} = {phi}{sub 9}-{phi}{sub 3} = {pi}/2. Here {phi}{sup 9} and {phi}{sub 3} are respectively the direction of the rotation axes of the 9 o'clock and 3 o'clock snakes relative to the design trajectory as shown in Figure 1. If the two snakes are slightly detuned by the same amount such that the rotation axes are no longer perpendicular, then the deviation of the closed-orbit spin tunemore » {nu}{sub 0} from 1/2 is given by {Delta}{nu}{sub 0} {approx_equal} ({Delta}{mu}){sup 2}/4{pi} cosG{gamma}{pi} - 2{Delta}{phi}/{pi} {approx_equal} 2{Delta}{phi}/180{sup o} with G{gamma} at a half integer, and where {Delta}{mu} is the deviation of snake rotation angle from 180{sup o}. It should be noted that there is a sign ambiguity in {Delta}{mu}{sub 0} since a spin tune of 0.495 is also a spin tune of 0.505, depending on the direction taken along the stable spin axis. In order to understand the effect of energy scaling on the snake axis direction, I have integrated the trajectory and spin rotation through a model of a RHIC snake (bi9-snk7) and found the energy (U) dependence of the snake axis angle {phi}{sub 9} and rotation angle {mu} as shown. A {approx_equal} p{sup -2} scaling of errors is typical in helical snakes. To first order, the orbit excursion drops as p{sup -1} and the spin precessions about transverse fields increase as {gamma} giving an approximate cancellation with energy, so we do not expect much change during the field ramp. The next order term which comes in is primarily proportional to p{sup -2}; although naively one might expect a slight effect inversely proportional to the velocity since {gamma}/p {proportional_to} c/{nu} {approx_equal} 1 + 1/2{gamma}{sup 2}.« less

Predictive discomfort in single- and combined-axis whole-body vibration considering different seated postures.

PubMed

DeShaw, Jonathan; Rahmatalla, Salam

2014-08-01

The aim of this study was to develop a predictive discomfort model in single-axis, 3-D, and 6-D combined-axis whole-body vibrations of seated occupants considering different postures. Non-neutral postures in seated whole-body vibration play a significant role in the resulting level of perceived discomfort and potential long-term injury. The current international standards address contact points but not postures. The proposed model computes discomfort on the basis of static deviation of human joints from their neutral positions and how fast humans rotate their joints under vibration. Four seated postures were investigated. For practical implications, the coefficients of the predictive discomfort model were changed into the Borg scale with psychophysical data from 12 volunteers in different vibration conditions (single-axis random fore-aft, lateral, and vertical and two magnitudes of 3-D). The model was tested under two magnitudes of 6-D vibration. Significant correlations (R = .93) were found between the predictive discomfort model and the reported discomfort with different postures and vibrations. The ISO 2631-1 correlated very well with discomfort (R2 = .89) but was not able to predict the effect of posture. Human discomfort in seated whole-body vibration with different non-neutral postures can be closely predicted by a combination of static posture and the angular velocities of the joint. The predictive discomfort model can assist ergonomists and human factors researchers design safer environments for seated operators under vibration. The model can be integrated with advanced computer biomechanical models to investigate the complex interaction between posture and vibration.

Relative importance of habitat filtering and limiting similarity on species assemblages of alpine and subalpine plant communities.

PubMed

Takahashi, Koichi; Tanaka, Saeka

2016-11-01

This study examined how habitat filtering and limiting similarity affect species assemblages of alpine and subalpine plant communities along a slope gradient on Mt. Norikura in central Japan. Plant traits (plant height, individual leaf area, specific leaf area (SLA), leaf linearity, leaf nitrogen and chlorophyll concentrations) and abiotic environmental factors (elevation, slope inclination, ground surface texture, soil water, soil pH, soil nutrient concentrations of NH 4 -N and NO 3 -N) were examined. The metrics of variance, range, kurtosis and the standard deviation of neighbor distance divided by the range of traits present (SDNDr) were calculated for each plant trait to measure trait distribution patterns. Limiting similarity was detected only for chlorophyll concentration. By contrast, habitat filtering was detected for individual leaf area, SLA, leaf linearity, chlorophyll concentration. Abiotic environmental factors were summarized by the principal component analysis (PCA). The first PCA axis positively correlated with elevation and soil pH, and negatively correlated with sand cover, soil water, NH 4 -N and NO 3 -N concentrations. High values of the first PCA axis represent the wind-exposed upper slope with lower soil moisture and nutrient availabilities. Plant traits changed along the first PCA axis. Leaf area, SLA and chlorophyll concentration decreased, and leaf linearity increased with the first PCA axis. This study showed that the species assemblage of alpine and subalpine plants was determined mainly by habitat filtering, indicating that abiotic environmental factors are more important for species assemblage than interspecific competition. Therefore, only species adapting to abiotic environments can distribute to these environments.

[Study on the characteristics of radiance calibration using nonuniformity extended source].

PubMed

Wang, Jian-Wei; Huang, Min; Xiangli, Bin; Tu, Xiao-Long

2013-07-01

Integrating sphere and diffuser are always used as extended source, and they have different effects on radiance calibration of imaging spectrometer with parameter difference. In the present paper, a mathematical model based on the theory of radiative transfer and calibration principle is founded to calculate the irradiance and calibration coefficients on CCD, taking relatively poor uniformity lights-board calibration system for example. The effects of the nonuniformity on the calibration was analyzed, which makes up the correlation of calibration coefficient matrix under ideal and unideal situation. The results show that the nonuniformity makes the viewing angle and the position of the point of intersection of the optical axis and the diffuse reflection plate have relatively large effects on calibration, while the observing distance's effect is small; under different viewing angles, a deviation value can be found that makes the calibration results closest to the desired results. So, the calibration error can be reduced by choosing appropriate deviation value.

Unified approach to probing Coulomb effects in tunnel ionization for any ellipticity of laser light.

PubMed

Landsman, A S; Hofmann, C; Pfeiffer, A N; Cirelli, C; Keller, U

2013-12-27

We present experimental data that show significant deviations from theoretical predictions for the location of the center of the electron momenta distribution at low values of ellipticity ε of laser light. We show that these deviations are caused by significant Coulomb focusing along the minor axis of polarization, something that is normally neglected in the analysis of electron dynamics, even in cases where the Coulomb correction is otherwise taken into account. By investigating ellipticity-resolved electron momenta distributions in the plane of polarization, we show that Coulomb focusing predominates at lower values of ellipticity of laser light, while Coulomb asymmetry becomes important at higher values, showing that these two complementary phenomena can be used to probe long-range Coulomb interaction at all polarizations of laser light. Our results suggest that both the breakdown of Coulomb focusing and the onset of Coulomb asymmetry are linked to the disappearance of Rydberg states with increasing ellipticity.

Compact cryogenic system with mechanical cryocoolers for antihydrogen synthesis.

PubMed

Shibata, M; Mohri, A; Kanai, Y; Enomoto, Y; Yamazaki, Y

2008-01-01

We have developed a compact cryogenic system which cools a vacuum chamber housing multi-ring trap electrodes (MRTs) of an antihydrogen synthesis trap using mechanical cryocoolers to achieve background pressure less than 10(-12) Torr. The vacuum chamber and the cryocoolers are thermally connected by copper strips of 99.9999% in purity. All components are installed within a diametric gap between the MRT of phi108 mm and a magnet bore of phi160 mm. An adjusting mechanism is prepared to align the MRT axis to the magnet axis. The vacuum chamber was successfully cooled down to 4.0 K after 14 h of cooling with heat load of 0.8 W.

Locking mechanism for indexing device

DOEpatents

Lindemeyer, Carl W.

1984-01-01

Disclosed is a locking mechanism for an indexing spindle. A conventional r gear having outwardly extending teeth is affixed to the spindle. Also included is a rotatably mounted camshaft whose axis is arranged in skewed relationship with the axis of the spindle. A disk-like wedge having opposing camming surfaces is eccentrically mounted on the camshaft. As the camshaft is rotated, the camming surfaces of the disc-like member are interposed between adjacent gear teeth with a wiping action that wedges the disc-like member between the gear teeth. A zero backlash engagement between disc-like member and gear results, with the engagement having a high mechanical advantage so as to effectively lock the spindle against bidirectional rotation.

Micro electro mechanical system optical switching

DOEpatents

Thorson, Kevin J; Stevens, Rick C; Kryzak, Charles J; Leininger, Brian S; Kornrumpf, William P; Forman, Glenn A; Iannotti, Joseph A; Spahn, Olga B; Cowan, William D; Dagel, Daryl J

2013-12-17

The present disclosure includes apparatus, system, and method embodiments that provide micro electo mechanical system optical switching and methods of manufacturing switches. For example, one optical switch embodiment includes at least one micro electro mechanical system type pivot mirror structure disposed along a path of an optical signal, the structure having a mirror and an actuator, and the mirror having a pivot axis along a first edge and having a second edge rotatable with respect to the pivot axis, the mirror being capable of and arranged to be actuated to pivot betweeen a position parallel to a plane of an optical signal and a position substantially normal to the plane of the optical signal.

Two-axis tracking solar collector mechanism

DOEpatents

Johnson, Kenneth C.

1992-01-01

This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion.

Two-axis tracking solar collector mechanism

DOEpatents

Johnson, Kenneth C.

1990-01-01

This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion.

RFQ device for accelerating particles

DOEpatents

Shepard, Kenneth W.; Delayen, Jean R.

1995-01-01

A superconducting radio frequency quadrupole (RFQ) device includes four spaced elongated, linear, tubular rods disposed parallel to a charged particle beam axis, with each rod supported by two spaced tubular posts oriented radially with respect to the beam axis. The rod and post geometry of the device has four-fold rotation symmetry, lowers the frequency of the quadrupole mode below that of the dipole mode, and provides large dipole-quadrupole mode isolation to accommodate a range of mechanical tolerances. The simplicity of the geometry of the structure, which can be formed by joining eight simple T-sections, provides a high degree of mechanical stability, is insensitive to mechanical displacement, and is particularly adapted for fabrication with superconducting materials such as niobium.

Two-axis tracking solar collector mechanism

DOEpatents

Johnson, K.C.

1992-12-08

This invention is a novel solar tracking mechanism incorporating a number of practical features that give it superior environmental resilience and exceptional tracking accuracy. The mechanism comprises a lightweight space-frame assembly supporting an array of point-focus Fresnel lenses in a two-axis tracking structure. The system is enclosed under a glass cover which isolates it from environmental exposure and enhances tracking accuracy by eliminating wind loading. Tracking accuracy is also enhanced by the system's broad-based tracking support. The system's primary intended application would be to focus highly concentrated sunlight into optical fibers for transmission to core building illumination zones, and the system may also have potential for photovoltaic or photothermal solar energy conversion. 16 figs.

Design and Development of a Two-Axis Thruster Gimbal with Xenon Propellant Lines

NASA Technical Reports Server (NTRS)

Asadurian, Armond

2010-01-01

A Two-Axis Thruster Gimbal was developed for a two degree-of-freedom tip-tilt gimbal application. This light weight gimbal mechanism is equipped with flexible xenon propellant lines and features numerous thermal control features for all its critical components. Unique thermal profiles and operating environments have been the key design drivers for this mechanism which is fully tolerant of extreme space environmental conditions. Providing thermal controls that are compatible with flexible components and are also capable of surviving launch vibration within this gimbal mechanism has proven to be especially demanding, requiring creativity and significant development effort. Some of these features, design drivers, and lessons learned will be examined herein.

Stress and the HPA Axis: Balancing Homeostasis and Fertility

PubMed Central

Whirledge, Shannon

2017-01-01

An organism’s reproductive fitness is sensitive to the environment, integrating cues of resource availability, ecological factors, and hazards within its habitat. Events that challenge the environment of an organism activate the central stress response system, which is primarily mediated by the hypothalamic–pituitary–adrenal (HPA) axis. The regulatory functions of the HPA axis govern the cardiovascular and metabolic system, immune functions, behavior, and reproduction. Activation of the HPA axis by various stressors primarily inhibits reproductive function and is able to alter fetal development, imparting a biological record of stress experienced in utero. Clinical studies and experimental data indicate that stress signaling can mediate these effects through direct actions in the brain, gonads, and embryonic tissues. This review focuses on the mechanisms by which stress activation of the HPA axis impacts fertility and fetal development. PMID:29064426

Application of External Axis in Robot-Assisted Thermal Spraying

NASA Astrophysics Data System (ADS)

Deng, Sihao; Fang, Dandan; Cai, Zhenhua; Liao, Hanlin; Montavon, Ghislain

2012-12-01

Currently, industrial robots are widely used in the process of thermal spraying because of their high efficiency, security, and repeatability. Although robots are found suitable for use in industrial productions, they have some natural disadvantages because of their six-axis mechanical linkages. When a robot performs a series of stages of production, it could be hard to move from one to another because a few axes reach their limit value. For this reason, an external axis should be added to the robot system to extend the reachable space of the robots. This article concerns the application of external axis on ABB robots in thermal spraying and the different methods of off-line programming with external axis in the virtual environment. The developed software toolkit was applied to coat real workpiece with a complex geometry in atmospheric plasma spraying).

In Vivo Tibial Fit and Rotational Analysis of a Customized, Patient-Specific TKA versus Off-the-Shelf TKA.

PubMed

Schroeder, Lennart; Martin, Gregory

2018-05-25

In total knee arthroplasty (TKA), surgeons often face the decision of maximizing tibial component fit and achieving correct rotational alignment at the same time. Customized implants (CIMs) address this difficulty by aiming to replicate the anatomical joint structure, utilizing data from patient-specific knee geometry during the manufacturing. We intraoperatively compared component fit in four tibial zones of a CIM to that of three different off-the-shelf (OTS) TKA designs in 44 knees. Additionally, we assessed the rotational alignment of the tibia using computed tomography (CT)-based computer aided design model analysis. Overall the CIM device showed significantly better component fit than the OTS TKAs. While 18% of OTS designs presented an implant overhang of 3 mm or more, none of the CIM components did ( p  < 0.05). There was a larger percentage of CIMs seen with optimal fit (≤1 mm implant overhang to ≤1 mm tibial bone undercoverage) than in OTS TKAs. Also, OTS implants showed significantly more component underhang of ≥3 mm than the CIM design (37 vs. 18%). The rotational analysis revealed that 45% of the OTS tibial components showed a rotational deviation of more than 5 degrees and 4% of more than 10 degrees to a tibial rotational axis described by Cobb et al. No deviation was seen for the CIM, as the device is designed along this axis. Using the medial one-third of the tibial tubercle as the rotational landmark, 95% of the OTS trays demonstrated a rotational deviation of more than 5 degrees and 73% of more than 10 degrees compared with 73% of CIM tibial trays with more than 5 degrees and 27% with more than 10 degrees. Based on our findings, we believe that the CIM TKA provides both better rotational alignment and tibial fit without causing overhang of the tibial tray than the three examined OTS implants. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Percentage depth dose calculation accuracy of model based algorithms in high energy photon small fields through heterogeneous media and comparison with plastic scintillator dosimetry

PubMed Central

Mani, Ganesh Kadirampatti; Karunakaran, Kaviarasu

2016-01-01

Small fields smaller than 4×4 cm2 are used in stereotactic and conformal treatments where heterogeneity is normally present. Since dose calculation accuracy in both small fields and heterogeneity often involves more discrepancy, algorithms used by treatment planning systems (TPS) should be evaluated for achieving better treatment results. This report aims at evaluating accuracy of four model‐based algorithms, X‐ray Voxel Monte Carlo (XVMC) from Monaco, Superposition (SP) from CMS‐Xio, AcurosXB (AXB) and analytical anisotropic algorithm (AAA) from Eclipse are tested against the measurement. Measurements are done using Exradin W1 plastic scintillator in Solid Water phantom with heterogeneities like air, lung, bone, and aluminum, irradiated with 6 and 15 MV photons of square field size ranging from 1 to 4 cm2. Each heterogeneity is introduced individually at two different depths from depth‐of‐dose maximum (Dmax), one setup being nearer and another farther from the Dmax. The central axis percentage depth‐dose (CADD) curve for each setup is measured separately and compared with the TPS algorithm calculated for the same setup. The percentage normalized root mean squared deviation (%NRMSD) is calculated, which represents the whole CADD curve's deviation against the measured. It is found that for air and lung heterogeneity, for both 6 and 15 MV, all algorithms show maximum deviation for field size 1×1 cm2 and gradually reduce when field size increases, except for AAA. For aluminum and bone, all algorithms' deviations are less for 15 MV irrespective of setup. In all heterogeneity setups, 1×1 cm2 field showed maximum deviation, except in 6 MV bone setup. All algorithms in the study, irrespective of energy and field size, when any heterogeneity is nearer to Dmax, the dose deviation is higher compared to the same heterogeneity far from the Dmax. Also, all algorithms show maximum deviation in lower‐density materials compared to high‐density materials. PACS numbers: 87.53.Bn, 87.53.kn, 87.56.bd, 87.55.Kd, 87.56.jf PMID:26894345

Analysis of a planetary-rotation system for evaporated optical coatings

DOE PAGES

Oliver, J. B.

2016-01-01

The impact of planetary-design considerations for optical coating deposition is analyzed, including the ideal number of planets, variations in system performance, and the deviation of planet motion from the ideal. System capacity is maximized for four planets, although substrate size can significantly influence this result. Guidance is provided in the design of high-performance deposition systems based on the relative impact of different error modes. As a result, errors in planet mounting such that the planet surface is not perpendicular to its axis of rotation are particularly problematic, suggesting planetary design modifications would be appropriate.

Interferometric rotation sensor

NASA Technical Reports Server (NTRS)

Walsh, T. M. (Inventor)

1973-01-01

An interferometric rotation sensor and control system is provided which includes a compound prism interferometer and an associated direction control system. Light entering the interferometer is split into two paths with the light in the respective paths being reflected an unequal number of times, and then being recombined at an exit aperture in phase differing relationships. Incoming light is deviated from the optical axis of the device by an angle, alpha. The angle causes a similar displacement of the two component images at the exit aperture which results in a fringe pattern. Fringe numbers are directly related to angle alpha. Various control systems of the interferometer are given.

N-(2-Allyl-4-eth­oxy-2H-indazol-5-yl)-4-methyl­benzene­sulfonamide

PubMed Central

Chicha, Hakima; Rakib, El Mostapha; Bouissane, Latifa; Viale, Maurizio; Saadi, Mohamed; El Ammari, Lahcen

2014-01-01

The indazole ring system of the title compound, C19H21N3O3S, is almost planar (r.m.s. deviation = 0.0192 Å) and forms dihedral angles of 77.99 (15) and 83.9 (3)° with the benzene ring and allyl group, respectively. In the crystal, centrosymmetrically related mol­ecules are connected by pairs of N—H⋯O hydrogen bonds into dimers, which are further linked by C—H⋯O hydrogen bonds, forming columns parallel to the b axis. PMID:24860413

Documentation of Current IDA Computer Material Developed for DCPA. Volume II,

DTIC Science & Technology

1977-01-01

Values of sums df input values.dumber of XTs in pcwer^x is raised to, number of Y’s in power 3 is peJOGtod to, e.g., SXXXY = NJRT x5. v.P. L 1...Convention as with SXX. Normalize by dividing by same powers of standard deviations as number of B’s or L’s. For two tract cities separation between...but in degress Tractional moments about principle axis. Here the number if B’s in L’s is the reciprocal of the power , e.g., FRBBBL= NfT (x

Benzil bis-(ketazine).

PubMed

Patra, Goutam Kumar; Mukherjee, Anindita; Ng, Seik Weng

2009-07-04

1,1',2,2'-tetra-phenyl-2,2'-azinodiethanone), C(28)H(20)N(2)O(2), was obtained by the reaction of benzil monohydrazone with chromium(III) nitrate. The dibenzyl-idene hydrazine unit is nearly planar (r.m.s. deviation = 0.073 Å) and the two benzoyl units are oriented almost perpendicular to it [dihedral angle = 87.81 (2), 87.81 (2)°]. The mol-ecules are linked into chains along the c axis by C-H⋯O hydrogen bonds and the chains are cross-linked via C-H⋯π inter-actions involving the benzoyl phenyl rings.

Experimental study on deep hole drilling of 17-4PH material

NASA Astrophysics Data System (ADS)

Uzhanfeng, LI; Uquantai, LI

2018-02-01

This paper uses 17-4PH material as the research object, according to the material characteristics of 17-4PH, designed and carried out deep hole drilling test. The purpose of the experiment is to study and discuss the three major problems of tool wear, chip shape and axial deviation of the hole in the process of deep hole drilling of 17-4PH materials. Through the deep hole drilling test of 17-4PH material, the variation of the chip shape and the deflection of the hole axis was obtained under different wear conditions.

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

Qing-He, Gao; Information Engineering College, Liaoning University of Traditional Chinese Medicine, Shenyang 110847; Zhi-Jun, Xu

The mechanical properties and structural evolution of Mo{sub 2}GaC are calculated by first-principles under pressure. Our results unexpectedly found that the c axis is always stiffer than a axis within 0–100 GPa. An ultraincompressibility of c axis within 15–60 GPa is observed, with a contraction of about 0.2 Å, slightly larger than that of a axis (0.14 Å). The abnormal expansion of c axis and the fast decrease in a axis above about 15 GPa and 70 GPa failed to induce the structural instability, whereas such behavior caused the elastic softening in many mechanical quantities. The shrinkage anomaly of c axis is closely reflected by themore » internal coordinate (u) shift of Mo atom as it shows three different slopes within 0–15 GPa, 20–60 GPa, and 70–100 GPa, respectively. The longest Mo-Mo bond is responsible for the unusual shrinkage of c-axis under pressure as they experience nearly identical pressure dependences, whereas the a axis presents certain response with the variation of C-Mo bond particularly at 70 GPa. The electronic properties are investigated, including the energy band and density of states, and so on. At G point of K-M line, the energy decreases at 10 GPa first and increases at 30 GPa subsequently, the critical point is at about 15 GPa, with respective values of −0.17 of 0 GPa, −0.18 of 10 GPa, −0.16 of 15 GPa, and −0.13 of 30 GPa, respectively. This alternative energy change of G point, which is the symmetry center of the rhombic parallelogram of Ga atoms and the midpoint of the two bonded Mo atoms, convincingly reveal the origin of the anomalous ultraincompressibility of c axis as the Mo-Mo bond length shrinkage has to overcome the increasing energy barrier height. The Mo-Mo bond population and the electronegativity investigations of the Mo atom further reveal the most likely origin of the ultraincompressibility of c axis. This interesting result expects further experimental confirmation as this is the first nanolaminate ceramics compound presenting quite low-pressure axial ultraincompressibility.« less

Modulation of the Hypothalamic-Pituitary-Adrenal Axis by Early Life Stress Exposure

PubMed Central

van Bodegom, Miranda; Homberg, Judith R.; Henckens, Marloes J. A. G.

2017-01-01

Exposure to stress during critical periods in development can have severe long-term consequences, increasing overall risk on psychopathology. One of the key stress response systems mediating these long-term effects of stress is the hypothalamic-pituitary-adrenal (HPA) axis; a cascade of central and peripheral events resulting in the release of corticosteroids from the adrenal glands. Activation of the HPA-axis affects brain functioning to ensure a proper behavioral response to the stressor, but stress-induced (mal)adaptation of the HPA-axis' functional maturation may provide a mechanistic basis for the altered stress susceptibility later in life. Development of the HPA-axis and the brain regions involved in its regulation starts prenatally and continues after birth, and is protected by several mechanisms preventing corticosteroid over-exposure to the maturing brain. Nevertheless, early life stress (ELS) exposure has been reported to have numerous consequences on HPA-axis function in adulthood, affecting both its basal and stress-induced activity. According to the match/mismatch theory, encountering ELS prepares an organism for similar (“matching”) adversities during adulthood, while a mismatching environment results in an increased susceptibility to psychopathology, indicating that ELS can exert either beneficial or disadvantageous effects depending on the environmental context. Here, we review studies investigating the mechanistic underpinnings of the ELS-induced alterations in the structural and functional development of the HPA-axis and its key external regulators (amygdala, hippocampus, and prefrontal cortex). The effects of ELS appear highly dependent on the developmental time window affected, the sex of the offspring, and the developmental stage at which effects are assessed. Albeit by distinct mechanisms, ELS induced by prenatal stressors, maternal separation, or the limited nesting model inducing fragmented maternal care, typically results in HPA-axis hyper-reactivity in adulthood, as also found in major depression. This hyper-activity is related to increased corticotrophin-releasing hormone signaling and impaired glucocorticoid receptor-mediated negative feedback. In contrast, initial evidence for HPA-axis hypo-reactivity is observed for early social deprivation, potentially reflecting the abnormal HPA-axis function as observed in post-traumatic stress disorder, and future studies should investigate its neural/neuroendocrine foundation in further detail. Interestingly, experiencing additional (chronic) stress in adulthood seems to normalize these alterations in HPA-axis function, supporting the match/mismatch theory. PMID:28469557

Small Aperture BPM to Quadrupole Assembly Tolerance Study

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

Fong, K. W.

2010-12-07

The LCLS injector and linac systems utilize a series of quadrupole magnets with a beam position monitor (BPM) captured in the magnet pole tips. The BPM measures the electron beam position by comparing the electrical signal from 4 electrodes and interpolating beam position from these signals. The manufacturing tolerances of the magnet and BPM are critical in determining the mechanical precision of the electrodes relative to the nominal electron beam Z-axis. This study evaluates the statistical uncertainty of the electrodes center axis relative to the nominal electron beam axis.

Endurance testing of downstream cathodes on a low-power MPD thruster

NASA Technical Reports Server (NTRS)

Burkhart, J. A.; Rose, J. R.

1974-01-01

A low-power MPD thruster with downstream cathode was tested for endurance with a series of hollow cathode designs. Failure modes and failure mechanisms were identified. A new hollow cathode (with rod inserts) has emerged which shows promise for long life. The downstream positioning of the cathode was also changed from an on-axis location to an off-axis location. Data are presented for a 1332-hour life test of this new hollow cathode located at the new off-axis location. Xenon propellant was used.

On LAM's and SAM's for Halley's rotation

NASA Technical Reports Server (NTRS)

Peale, Stanton J.

1992-01-01

Non principal axis rotation for comet Halley is inferred from dual periodicities evident in the observations. The modes where the spin axis precesses around the axis of minimum moment of inertia (long axis mode or LAM) and where it precesses around the axis of maximum moment of inertia (short axis mode or SAM) are described from an inertial point of view. The currently favored LAM model for Halley's rotation state satisfies observational and dynamical constraints that apparently no SAM can satisfy. But it cannot reproduce the observed post perihelion brightening through seasonal illumination of localized sources on the nucleus, whereas a SAM can easily produce post or pre perihelion brightening by this mechanism. However, the likelihood of a LAM rotation for elongated nuclei of periodic comets such as Halley together with Halley's extreme post perihelion behavior far from the Sun suggest that Halley's post perihelion brightening may be due to effects other than seasonal illumination of localized sources, and therefore such brightening may not constrain its rotation state.

Interaction of PGHS-2 and glutamatergic mechanisms controlling the ovine fetal hypothalamus-pituitary-adrenal axis

PubMed Central

Knutson, Nathan

2010-01-01

Prostaglandins, generated within the fetal brain, are integral components of the mechanism controlling the fetal hypothalamus-pituitary-adrenal (HPA) axis. Previous studies in this laboratory demonstrated that prostaglandin G/H synthase isozyme 2 (PGHS-2) inhibition reduces the fetal HPA axis response to cerebral hypoperfusion, blocks the preparturient rise in fetal plasma ACTH concentration, and delays parturition. We also discovered that blockade of N-methyl-d-aspartate (NMDA) receptors reduces the fetal ACTH response to cerebral hypoperfusion. The present study was designed to test the hypothesis that PGHS-2 action and the downstream effect of HPA axis stimulation are stimulated by NMDA-mediated glutamatergic neurotransmission. Chronically catheterized late-gestation fetal sheep (n = 8) were injected with NMDA (1 mg iv). All responded with increases in fetal plasma ACTH and cortisol concentrations. Pretreatment with resveratrol (100 mg iv, n = 5), a specific inhibitor of PGHS-1, did not alter the magnitude of the HPA axis response to NMDA. Pretreatment with nimesulide (10 mg iv, n = 6), a specific inhibitor of PGHS-2, significantly reduced the HPA axis response to NMDA. To further explore this interaction, we injected NMDA in six chronically catheterized fetal sheep that were chronically infused with nimesulide (n = 6) at a rate of 1 mg/day into the lateral cerebral ventricle for 5–7 days. In this group, there was no significant ACTH response to NMDA. Finally, we tested whether the HPA axis response to prostaglandin E2 (PGE2) is mediated by NMDA receptors. Seven chronically catheterized late-gestation fetal sheep were injected with 100 ng of PGE2, which significantly increased fetal plasma ACTH and cortisol concentrations. Pretreatment with ketamine (10 mg iv), an NMDA antagonist, did not alter the ACTH or cortisol response to PGE2. We conclude that generation of prostanoids via the action of PGHS-2 in the fetal brain augments the fetal HPA axis response to NMDA-mediated glutamatergic stimulation. PMID:20445154

Mechanical responses of a-axis GaN nanowires under axial loads

NASA Astrophysics Data System (ADS)

Wang, R. J.; Wang, C. Y.; Feng, Y. T.; Tang, Chun

2018-03-01

Gallium nitride (GaN) nanowires (NWs) hold technological significance as functional components in emergent nano-piezotronics. However, the examination of their mechanical responses, especially the mechanistic understanding of behavior beyond elasticity (at failure) remains limited due to the constraints of in situ experimentation. We therefore performed simulations of the molecular dynamics (MD) of the mechanical behavior of [1\\bar{2}10]-oriented GaN NWs subjected to tension or compression loading until failure. The mechanical properties and critical deformation processes are characterized in relation to NW sizes and loading conditions. Detailed examinations revealed that the failure mechanisms are size-dependent and controlled by the dislocation mobility on shuffle-set pyramidal planes. The size dependence of the elastic behavior is also examined in terms of the surface structure determined modification of Young’s modulus. In addition, a comparison with c-axis NWs is made to show how size-effect trends vary with the growth orientation of NWs.

5. LOOKING WEST ALONG THE AXIS OF THE DAM TOWARD ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. LOOKING WEST ALONG THE AXIS OF THE DAM TOWARD THE OUTLET STRUCTURE. HAND OPERATED MECHANICAL TAMPERS ARE COMPACTING THE FILL ALONG THE STEEL SHEET PILING CUTOFF WALL IN THE FOREGROUND. Volume XIX, No. 6, April 12, 1940. - Prado Dam, Santa Ana River near junction of State Highways 71 & 91, Corona, Riverside County, CA

Early-Life Stress, HPA Axis Adaptation, and Mechanisms Contributing to Later Health Outcomes

PubMed Central

Maniam, Jayanthi; Antoniadis, Christopher; Morris, Margaret J.

2014-01-01

Stress activates the hypothalamic–pituitary–adrenal (HPA) axis, which then modulates the degree of adaptation and response to a later stressor. It is known that early-life stress can impact on later health but less is known about how early-life stress impairs HPA axis activity, contributing to maladaptation of the stress–response system. Early-life stress exposure (either prenatally or in the early postnatal period) can impact developmental pathways resulting in lasting structural and regulatory changes that predispose to adulthood disease. Epidemiological, clinical, and experimental studies have demonstrated that early-life stress produces long term hyper-responsiveness to stress with exaggerated circulating glucocorticoids, and enhanced anxiety and depression-like behaviors. Recently, evidence has emerged on early-life stress-induced metabolic derangements, for example hyperinsulinemia and altered insulin sensitivity on exposure to a high energy diet later in life. This draws our attention to the contribution of later environment to disease vulnerability. Early-life stress can alter the expression of genes in peripheral tissues, such as the glucocorticoid receptor and 11-beta hydroxysteroid dehydrogenase (11β-HSD1). We propose that interactions between altered HPA axis activity and liver 11β-HSD1 modulates both tissue and circulating glucocorticoid availability, with adverse metabolic consequences. This review discusses the potential mechanisms underlying early-life stress-induced maladaptation of the HPA axis, and its subsequent effects on energy utilization and expenditure. The effects of positive later environments as a means of ameliorating early-life stress-induced health deficits, and proposed mechanisms underpinning the interaction between early-life stress and subsequent detrimental environmental exposures on metabolic risk will be outlined. Limitations in current methodology linking early-life stress and later health outcomes will also be addressed. PMID:24860550

System for Centering a Turbofan in a Nacelle During Tests

NASA Technical Reports Server (NTRS)

Cunningham, Cameron C.; Thompson, William K.; Hughes, Christopher E.; Shook, Tony D.

2003-01-01

A feedback position-control system has been developed for maintaining the concentricity of a turbofan with respect to a nacelle during acoustic and flow tests in a wind tunnel. The system is needed for the following reasons: Thermal and thrust loads can displace the fan relative to the nacelle; In the particular test apparatus (see Figure 1), denoted as a rotor-only nacelle (RAN), the struts, vanes, and other stator components of a turbofan engine that ordinarily maintain the required concentricity in the face of thermal and thrust loads are not present; and The struts and stator components are not present because it is necessary to provide a flow path that is acoustically clean in the sense that the measured noise can be attributed to the fan alone. The system is depicted schematically in Figure 2. The nacelle is supported by two struts attached to a two-axis traverse table located outside the wind-tunnel wall. Two servomotors acting through 100:1 gearboxes drive the table along the Y and Z axes, which are perpendicular to the axis of rotation. The Y and Z components of the deviation from concentricity are measured by four laser displacement sensors mounted on the nacelle and aimed at reflective targets on the center body, which is part of the fan assembly. The outputs of the laser displacement sensors are digitized and processed through a personal computer programmed with control software. The control output of the computer commands the servomotors to move the table as needed to restore concentricity. Numerous software and hardware travel limits and alarms are provided to maximize safety. A highly ablative rub strip in the nacelle minimizes the probability of damage in the event that a deviation from concentricity exceeds the radial clearance [<0.004 in. (<0.1 mm)] between the inner surface of the nacelle and the tips of the fan blades. To be able to prevent an excursion in excess of the tip clearance, the system must be accurate enough to control X and Y displacements to within 0.001 in. (.0.025 mm). One characteristic essential to such accuracy is sufficient rigidity in the mechanical components of the system to prevent excitation of vibrations in the strut/ nacelle subsystem. The need for such a high degree of accuracy prompted a comprehensive analysis of sources of measurement and control errors, followed by rigorous design efforts to minimize these errors. As a result, the design of the system incorporates numerous improvements in hardware, software, and operational procedures.

Implications of microbiota and bile acid in liver injury and regeneration

PubMed Central

Liu, Hui-Xin; Keane, Ryan; Sheng, Lili; Wan, Yu-Jui Yvonne

2015-01-01

Summary Studies examining the mechanisms by which the liver injures and regenerates usually focus on factors and pathways within the liver, neglecting the signaling derived from the gut-liver axis. The intestinal content is rich in microorganisms as well as metabolites generated from both the host and colonizing bacteria. Via the gut-liver axis, this complex “soup” exerts an immense impact on liver integrity and function. This review article summarizes data published in the past 30 years that have demonstrated the signaling derived from the gut-liver axis in relation to liver injury and regeneration. Despite many correlative findings, the intricate networks of pathways involved along with a scarcity of mechanistic data urgently require nutrigenomic, metabolomics, and microbiota profiling approaches to provide a deep understanding of the interplay between nutrition, bacteria, and host response. Such knowledge would better elucidate the molecular mechanisms that link microbiota alteration to host physiological response and vice-versa. PMID:26256437

Human longevity is characterised by high thyroid stimulating hormone secretion without altered energy metabolism.

PubMed

Jansen, S W; Akintola, A A; Roelfsema, F; van der Spoel, E; Cobbaert, C M; Ballieux, B E; Egri, P; Kvarta-Papp, Z; Gereben, B; Fekete, C; Slagboom, P E; van der Grond, J; Demeneix, B A; Pijl, H; Westendorp, R G J; van Heemst, D

2015-06-19

Few studies have included subjects with the propensity to reach old age in good health, with the aim to disentangle mechanisms contributing to staying healthier for longer. The hypothalamic-pituitary-thyroid (HPT) axis maintains circulating levels of thyroid stimulating hormone (TSH) and thyroid hormone (TH) in an inverse relationship. Greater longevity has been associated with higher TSH and lower TH levels, but mechanisms underlying TSH/TH differences and longevity remain unknown. The HPT axis plays a pivotal role in growth, development and energy metabolism. We report that offspring of nonagenarians with at least one nonagenarian sibling have increased TSH secretion but similar bioactivity of TSH and similar TH levels compared to controls. Healthy offspring and spousal controls had similar resting metabolic rate and core body temperature. We propose that pleiotropic effects of the HPT axis may favour longevity without altering energy metabolism.

Fast Estimation of Strains for Cross-Beams Six-Axis Force/Torque Sensors by Mechanical Modeling

PubMed Central

Ma, Junqing; Song, Aiguo

2013-01-01

Strain distributions are crucial criteria of cross-beams six-axis force/torque sensors. The conventional method for calculating the criteria is to utilize Finite Element Analysis (FEA) to get numerical solutions. This paper aims to obtain analytical solutions of strains under the effect of external force/torque in each dimension. Genetic mechanical models for cross-beams six-axis force/torque sensors are proposed, in which deformable cross elastic beams and compliant beams are modeled as quasi-static Timoshenko beam. A detailed description of model assumptions, model idealizations, application scope and model establishment is presented. The results are validated by both numerical FEA simulations and calibration experiments, and test results are found to be compatible with each other for a wide range of geometric properties. The proposed analytical solutions are demonstrated to be an accurate estimation algorithm with higher efficiency. PMID:23686144

Seismicity and state of stress near the Japan Trench axis off Miyagi, northeast Japan, after the 2011 Tohoku-Oki earthquake

NASA Astrophysics Data System (ADS)

Obana, K.; Kodaira, S.; Takahashi, T.; Yamamoto, Y.; Nakamura, Y.; No, T.; Fujie, G.; Hino, R.; Shinohara, M.

2013-12-01

The 2011 Tohoku-Oki earthquake ruptured roughly 200 km wide and 500 km long megathrust along the Japan Trench. The rupture propagated to the trench axis with a maximum slip about 50 m near the trench axis. As a consequence of this large near-trench slip, earthquakes have been activated near the axis of the Japan Trench off Miyagi, northeast Japan. We have conducted ocean bottom seismograph (OBS) experiments in the Japan Trench axis area, surrounding area of the IODP JFAST drilling site, since the occurrence of the 2011 Tohoku-Oki earthquake. Although conventionally used OBS cannot be deployed at seafloor deeper than 6000 m water depth, we used newly developed ultra-deep OBS using ceramic sphere, which can be deployed at a depth of 9000 m, for the observations in the trench axis. The ultra-deep OBS has almost equivalent dimensions and weight with the conventionally used OBS, thus we can handle it in the same manner with the conventionally OBS without any special operation. As a result of a series of the OBS observations, we obtained accurate hypocenter locations and focal mechanisms in both seaward and landward of the trench axis. Earthquakes near the trench axis area were located within the overriding and incoming/subducting plates with very few on the plate interface below the inner trench slope landward of the trench axis. Most of the earthquakes both in the overriding and incoming/subducting plates having normal or strike-slip faulting focal mechanisms with T-axis normal to the trench axis. This indicates that tensional stress is dominant in the trench axis area. However, most seaward part of the seismicity within the overriding plate is characterized by a localized cluster of trench-normal compressional earthquakes, which may relate to spatial variation of the frictional behavior of the shallowest part of the megathrust. On the other hand, trench-normal extensional earthquakes in the incoming/subducting Pacific plate were located at depths shallower than about 35 to 40 km. The deepest trench-normal extensional earthquake observed during OBS observations from December 2012 to January 2013 is slightly shallower than that observed from May to June in 2011 but further observations are required to investigate the temporal change. Continued and repeated earthquake observations could provide information on post-seismic behavior of the megathrust and recovery process of the stress state.

Is radiographic measurement of bony landmarks reliable for lateral meniscal sizing?

PubMed

Yoon, Jung-Ro; Kim, Taik-Seon; Lim, Hong-Chul; Lim, Hyung-Tae; Yang, Jae-Hyuk

2011-03-01

The accuracy of meniscal measurement methods is still in debate. The authors' protocol for radiologic measurements will provide reproducible bony landmarks, and this measurement method of the lateral tibial plateau will correlate with the actual anatomic value. Controlled laboratory study. Twenty-five samples of fresh lateral meniscus with attached proximal tibia were obtained during total knee arthroplasty. Each sample was obtained without damage to the meniscus and bony attachment sites. The inclusion criterion was mild to moderate osteoarthritis in patients with mechanical axis deviation of less than 15°. Knees with lateral compartment osteoarthritic change or injured or degenerated menisci were excluded. For the lateral tibial plateau length measurements, the radiographic beam was angled 10° caudally at neutral rotation, which allowed differentiation of the lateral plateau cortical margins from the medial plateau. The transition points were identified and used for length measurement. The values of length were then compared with the conventional Pollard method and the anatomic values. The width measurement was done according to Pollard's protocol. For each knee, the percentage deviation from the anatomic dimension was recorded. Intraobserver error and interobserver error were calculated. The deviation of the authors' radiographic length measurements from anatomic dimensions was 1.4 ± 1.1 mm. The deviation of Pollard's radiographic length measurements was 4.1 ± 2.0 mm. With respect to accuracy-which represents the frequency of measurements that fall within 10% of measurements-the accuracy of authors' length was 98%, whereas for Pollard's method it was 40%. There was a good correlation between anatomic meniscal dimensions and each radiologic plateau dimensions for lateral meniscal width (R(2) = .790) and the authors' lateral meniscal length (R(2) = .823) and fair correlation for Pollard's lateral meniscal length (R(2) = .660). The reliability of each radiologic measurement showed good reliability (intraclass correlation coefficients, .823 to .973). The authors tried to determine the best-fit equation for predicting meniscal size from Pollard's method of bone size, as follows: anatomic length = 0.52 × plateau length (according to Pollard's method) + 5.2, not as Pollard suggested (0.7 × Pollard's plateau length). Based on this equation-namely, the modified Pollard method-the percentage difference decreased, and the accuracy increased to 92%. Lateral meniscal length dimension can be accurately predicted from the authors' radiographic tibial plateau measurements. This study may provide valuable information in preoperative sizing of lateral meniscus in meniscal allograft transplantation.

Developmental and Functional Effects of Steroid Hormones on the Neuroendocrine Axis and Spinal Cord

PubMed Central

Zubeldia-Brenner, L; Roselli, CE; Recabarren, SE; Gonzalez Deniselle, MC; Lara, HE

2016-01-01

This review highlights the principal effects of steroid hormones at central and peripheral levels in the neuroendocrine axis. The data discussed here points out the principal role of estrogens and testosterone in hormonal programming in relation to sexual orientation, reproductive and metabolic programming, and in the neuroendocrine mechanism involved in development of polycystic ovary syndrome phenotype. Moreover, consistent with the wide range of processes in which steroid hormones take part, we discuss the protective effects of progesterone on neurodegenerative disease and the signaling mechanism involved in the genesis of estrogen-induced pituitary prolactinomas. PMID:27262161

A self-calibration method in single-axis rotational inertial navigation system with rotating mechanism

NASA Astrophysics Data System (ADS)

Chen, Yuanpei; Wang, Lingcao; Li, Kui

2017-10-01

Rotary inertial navigation modulation mechanism can greatly improve the inertial navigation system (INS) accuracy through the rotation. Based on the single-axis rotational inertial navigation system (RINS), a self-calibration method is put forward. The whole system is applied with the rotation modulation technique so that whole inertial measurement unit (IMU) of system can rotate around the motor shaft without any external input. In the process of modulation, some important errors can be decoupled. Coupled with the initial position information and attitude information of the system as the reference, the velocity errors and attitude errors in the rotation are used as measurement to perform Kalman filtering to estimate part of important errors of the system after which the errors can be compensated into the system. The simulation results show that the method can complete the self-calibration of the single-axis RINS in 15 minutes and estimate gyro drifts of three-axis, the installation error angle of the IMU and the scale factor error of the gyro on z-axis. The calibration accuracy of optic gyro drifts could be about 0.003°/h (1σ) as well as the scale factor error could be about 1 parts per million (1σ). The errors estimate reaches the system requirements which can effectively improve the longtime navigation accuracy of the vehicle or the boat.

Patient satisfaction with correction of congenital penile curvature.

PubMed

Mayer, M; Rey Valzacchi, G; Silva Garretón, A; Layus, O; Gueglio, G

2017-12-29

Congenital penile curvature is a relatively rare disease, resulting from a deviation of the penis from the body's straight axis when erect. The prevalence is difficult to determine. Although it has been suggested that the condition could affect up to 10% of the male population, most of these deviations are minor, with no clinical or psychological importance, which leads to its underdiagnosis. Effective correction of the deviation can markedly improve the quality of life of adolescents with this condition. To assess the quality of the sex life of patients diagnosed with congenital penile curvature who underwent surgical correction. Design Retrospective, observational cohort study. Data was collected from the medical records of patients who underwent surgical correction of congenital penile curvature from June 2004 to August 2016. The patients completed the following self-administered questionnaires: Sexual Quality of Life Questionnaire-Male (SQOL-M), International Index of Erectile Function 5 (IIEF 5) and "How satisfied are you with the results of the surgery? From 0 to 10". Twenty-two corporoplasties were performed to correct the patients' congenital penile curvature. The patients' average age was 23.4 years (range, 17-35). The mean deviation prior to surgery was 47.9° (range, 20°-90°). The average score on the SQOL-M was 52 points (range, 6-66). The average score on the IIEF 5 was 22.4 points. Congenital penile curvature profoundly decreases quality of life, and early surgery is fundamental for repairing the anatomical deformation and thereby significantly restores the patients' psychosocial and sexual wellbeing. Copyright © 2017 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

Characterization and optimization of slanted well designs for microfluidic mixing under electroosmotic flow.

PubMed

Johnson, Timothy J; Locascio, Laurie E

2002-08-01

Recently, a series of slanted wells on the floor of a microfluidic channel were experimentally shown to successfully induce off-axis transport and mixing of two confluent streams when operating under electroosmotic (EO) flow. This paper will further explore, through numerical simulations, the parameters that affect off-axis transport under EO flow with an emphasis on optimizing the mixing rate of (a). two confluent streams in steady-state or (b). the transient scenario of two confluent plugs of material, which simulates mixing after an injection. For the steady-state scenario, the degree of mixing was determined to increase by changing any of the following parameters: (1). increasing the well depth, (2). decreasing the well angle relative to the axis of the channel, and (3). increasing the EO mobility of the well walls relative to the mobility of the main channel. Also, it will be shown that folding of the fluid can occur when the well angle is sufficiently reduced and/or when the EO mobility of the wells is increased relative to the channel. The optimum configuration for the transient problem of mixing two confluent plugs includes shallow wells to minimize the well residence time, and an increased EO mobility of the well walls relative to the main channel as well as small well angles to maximize off-axis transport. The final design reported here for the transient study reduces the standard deviation of the concentration across the channel by 72% while only increasing the axial dispersion of the injected plug by 8.6 % when compared to a plug injected into a channel with no wells present. These results indicate that a series of slanted wells on the wall of a microchannel provides a means for controlling and achieving a high degree of off-axis transport and mixing in a passive manner for micro total analysis system (microTAS) devices that are driven by electroosmosis.

Analytical linear energy transfer model including secondary particles: calculations along the central axis of the proton pencil beam

NASA Astrophysics Data System (ADS)

Marsolat, F.; De Marzi, L.; Pouzoulet, F.; Mazal, A.

2016-01-01

In proton therapy, the relative biological effectiveness (RBE) depends on various types of parameters such as linear energy transfer (LET). An analytical model for LET calculation exists (Wilkens’ model), but secondary particles are not included in this model. In the present study, we propose a correction factor, L sec, for Wilkens’ model in order to take into account the LET contributions of certain secondary particles. This study includes secondary protons and deuterons, since the effects of these two types of particles can be described by the same RBE-LET relationship. L sec was evaluated by Monte Carlo (MC) simulations using the GATE/GEANT4 platform and was defined by the ratio of the LET d distributions of all protons and deuterons and only primary protons. This method was applied to the innovative Pencil Beam Scanning (PBS) delivery systems and L sec was evaluated along the beam axis. This correction factor indicates the high contribution of secondary particles in the entrance region, with L sec values higher than 1.6 for a 220 MeV clinical pencil beam. MC simulations showed the impact of pencil beam parameters, such as mean initial energy, spot size, and depth in water, on L sec. The variation of L sec with these different parameters was integrated in a polynomial function of the L sec factor in order to obtain a model universally applicable to all PBS delivery systems. The validity of this correction factor applied to Wilkens’ model was verified along the beam axis of various pencil beams in comparison with MC simulations. A good agreement was obtained between the corrected analytical model and the MC calculations, with mean-LET deviations along the beam axis less than 0.05 keV μm-1. These results demonstrate the efficacy of our new correction of the existing LET model in order to take into account secondary protons and deuterons along the pencil beam axis.

RFQ device for accelerating particles

DOEpatents

Shepard, K.W.; Delayen, J.R.

1995-06-06

A superconducting radio frequency quadrupole (RFQ) device includes four spaced elongated, linear, tubular rods disposed parallel to a charged particle beam axis, with each rod supported by two spaced tubular posts oriented radially with respect to the beam axis. The rod and post geometry of the device has four-fold rotation symmetry, lowers the frequency of the quadrupole mode below that of the dipole mode, and provides large dipole-quadrupole mode isolation to accommodate a range of mechanical tolerances. The simplicity of the geometry of the structure, which can be formed by joining eight simple T-sections, provides a high degree of mechanical stability, is insensitive to mechanical displacement, and is particularly adapted for fabrication with superconducting materials such as niobium. 5 figs.

Multi-access laser communications transceiver system

NASA Technical Reports Server (NTRS)

Ross, Monte (Inventor); Lokerson, Donald C. (Inventor); Fitzmaurice, Michael W. (Inventor); Meyer, Daniel D. (Inventor)

1993-01-01

A satellite system for optical communications such as a multi-access laser transceiver system. Up to six low Earth orbiting satellites send satellite data to a geosynchronous satellite. The data is relayed to a ground station at the Earth's surface. The earth pointing geosynchronous satellite terminal has no gimbal but has a separate tracking mechanism for tracking each low Earth orbiting satellite. The tracking mechanism has a ring assembly rotatable about an axis coaxial with the axis of the field of view of the geosynchronous satellite and a pivotable arm mounted for pivotal movement on the ring assembly. An optical pickup mechanism at the end of each arm is positioned for optical communication with one of the orbiting satellites by rotation of the ring.

Statistical analysis of road-vehicle-driver interaction as an enabler to designing behavioural models

NASA Astrophysics Data System (ADS)

Chakravarty, T.; Chowdhury, A.; Ghose, A.; Bhaumik, C.; Balamuralidhar, P.

2014-03-01

Telematics form an important technology enabler for intelligent transportation systems. By deploying on-board diagnostic devices, the signatures of vehicle vibration along with its location and time are recorded. Detailed analyses of the collected signatures offer deep insights into the state of the objects under study. Towards that objective, we carried out experiments by deploying telematics device in one of the office bus that ferries employees to office and back. Data is being collected from 3-axis accelerometer, GPS, speed and the time for all the journeys. In this paper, we present initial results of the above exercise by applying statistical methods to derive information through systematic analysis of the data collected over four months. It is demonstrated that the higher order derivative of the measured Z axis acceleration samples display the properties Weibull distribution when the time axis is replaced by the amplitude of such processed acceleration data. Such an observation offers us a method to predict future behaviour where deviations from prediction are classified as context-based aberrations or progressive degradation of the system. In addition we capture the relationship between speed of the vehicle and median of the jerk energy samples using regression analysis. Such results offer an opportunity to develop a robust method to model road-vehicle interaction thereby enabling us to predict such like driving behaviour and condition based maintenance etc.

Short circuit: Disaggregation of adrenocorticotropic hormone and cortisol levels in HIV-positive, methamphetamine-using men who have sex with men.

PubMed

Carrico, Adam W; Rodriguez, Violeta J; Jones, Deborah L; Kumar, Mahendra

2018-01-01

This study examined if methamphetamine use alone (METH + HIV-) and methamphetamine use in combination with HIV (METH + HIV+) were associated with hypothalamic-pituitary-adrenal (HPA) axis dysregulation as well as insulin resistance relative to a nonmethamphetamine-using, HIV-negative comparison group (METH-HIV-). Using an intact groups design, serum levels of HPA axis hormones in 46 METH + HIV- and 127 METH + HIV+ men who have sex with men (MSM) were compared to 136 METH-HIV- men. There were no group differences in prevailing adrenocorticotropic hormone (ACTH) or cortisol levels, but the association between ACTH and cortisol was moderated by METH + HIV+ group (β = -0.19, p < .05). Compared to METH-HIV- men, METH + HIV+ MSM displayed 10% higher log 10 cortisol levels per standard deviation lower ACTH. Both groups of methamphetamine-using MSM had lower insulin resistance and greater syndemic burden (i.e., sleep disturbance, severe depression, childhood trauma, and polysubstance use disorder) compared to METH-HIV- men. However, the disaggregated functional relationship between ACTH and cortisol in METH + HIV+ MSM was independent of these factors. Further research is needed to characterize the bio-behavioral pathways that explain dysregulated HPA axis functioning in HIV-positive, methamphetamine-using MSM. Copyright © 2017 John Wiley & Sons, Ltd.

ORIENTATION AND LOCUS OF TROPIC PHOTORECEPTOR MOLECULES IN SPORES OF BOTRYTIS AND OSMUNDA

PubMed Central

Jaffe, Lionel; Etzold, Helmut

1962-01-01

Study of the tropic responses of Botrytis cinerea and Osmunda cinnamomea spores to blue light shows the photoreceptor molecules to be highly dichroic and oriented: in Botrytis their axes of maximum absorption lie perpendicular to the nearby cell surface; in Osmunda, parallel. The chief evidence lies in a comparison of their responses to plane polarized light—both germinate parallel to the vibration planes (defined by the axis of vibration of the electric vector and the axis of light propagation)—with those to partial illumination with unpolarized light: Botrytis grows from its brighter part; Osmunda, from its darker. The degree of orientation produced by polarized light corresponds, at high intensities, to that produced by the imposition of such large (about 100 per cent) intensity differences across a cell as to preclude all alternatives to oriented dichroic receptors. The photoreceptors of the Botrytis spore lie within the cell wall's inner half. The chief evidence lies in the component of its tropic responses to polarized light within the vibration plane: germination peaks about 10° off the vibration axis. This deviation arises from focusing which is effective only in the wall's inner half. At high intensities, anomalies appear in Botrytis which are interpreted as "centering," i.e., a tendency toward growth from the center of two or more equally illuminated points of a cell rather than from one of them. PMID:14450869

Detection of defects in formed sheet metal using medial axis transformation

NASA Astrophysics Data System (ADS)

Murmu, Naresh C.; Velgan, Roman

2003-05-01

In the metal forming processes, the sheet metals are often prone to various defects such as thinning, dents, wrinkles etc. In the present manufacturing environments with ever increasing demand of higher quality, detecting the defects of formed sheet metal using an effective and objective inspection system is the foremost norm to remain competitive in market. The defect detection using optical techniques aspire to satisfy its needs to be non-contact and fast. However, the main difficulties to achieve this goal remain essentially on the development of efficient evaluation technique and accurate interpretation of extracted data. The defect like thinning is detected by evaluating the deviations of the thickness in the formed sheet metal against its nominal value. The present evaluation procedure for determination of thickness applied on the measurements data is not without deficiency. To improve this procedure, a new evaluation approach based on medial axis transformation is proposed here. The formed sheet metals are digitized using fringe projection systems in different orientations, and afterwards registered into one coordinate frame. The medial axis transformation (MAT) is applied on the point clouds, generating the point clouds of MAT. This data is further processed and medial surface is determined. The thinning defect is detected by evaluating local wall thickness and other defects like wrinkles are determined using the shape recognition on the medial surface. The applied algorithm is simple, fast and robust.

Biaxial potential of surface-stabilized ferroelectric liquid crystals

NASA Astrophysics Data System (ADS)

Kaznacheev, Anatoly; Pozhidaev, Evgeny; Rudyak, Vladimir; Emelyanenko, Alexander V.; Khokhlov, Alexei

2018-04-01

A biaxial surface potential Φs of smectic-C* surface-stabilized ferroelectric liquid crystals (SSFLCs) is introduced in this paper to explain the experimentally observed electric-field dependence of polarization P˜cell(E ) , in particular the shape of the static hysteresis loops. Our potential consists of three independent parts. The first nonpolar part Φn describes the deviation of the prime director n (which is the most probable orientation of the long molecular axes) from the easy alignment axis R , which is located in the boundary surface plane. It is introduced in the same manner as the uniaxial Rapini potential. The second part Φp of the potential is a polar term associated with the presence of the polar axis in a FLC. The third part Φm relates to the inherent FLC biaxiality, which has not been taken into consideration previously. The Φm part takes into account the deviations of the secondary director m (which is the most probable orientation of the short molecular axes) from the normal to the boundary surface. The overall surface potential Φs, which is a sum of Φn,Φp , and Φm, allows one to model the conditions when either one, two, or three minima of the SSFLC cell free energy are realized depending on the biaxiality extent. A monodomain or polydomain structure, as well as the bistability or monostability of SSFLC cells, depends on the number of free-energy minima, as confirmed experimentally. In this paper, we analyze the biaxiality impact on the FLC alignment. We also answer the question of whether the bistable or monostable structure can be formed in an SSFLC cell. Our approach is essentially based on a consideration of the biaxial surface potential, while the uniaxial surface potential cannot adequately describe the experimental observations in the FLC.

The accuracy and the safety of individualized 3D printing screws insertion templates for cervical screw insertion.

PubMed

Deng, Ting; Jiang, Minghui; Lei, Qing; Cai, Lihong; Chen, Li

2016-12-01

Clinical trial for cervical screw insertion by using individualized 3-dimensional (3D) printing screw insertion templates device. The objective of this study is to evaluate the safety and accuracy of the individualized 3D printing screw insertion template in the cervical spine. Ten patients who underwent posterior cervical fusion surgery with cervical pedicle screws, laminar screws or lateral mass screws between December 2014 and December 2015 were involved in this study. The patients were examined by CT scan before operation. The individualized 3D printing templates were made with photosensitive resin by a 3D printing system to ensure the screw shafts entered the vertebral body without breaking the pedicle or lamina cortex. The templates were sterilized by a plasma sterilizer and used during the operation. The accuracy and the safety of the templates were evaluated by CT scans at the screw insertion levels after operation. The accuracy of this patient-specific template technique was demonstrated. Only one screw axis greatly deviated from the planned track and breached the cortex of the pedicle because the template was split by rough handling and then we inserted the screws under the fluoroscopy. The remaining screws were inserted in the track as preoperative design and the screw axis deviated by less than 2 mm. Vascular or neurologic complications or injuries did not happen. And no infection, broken nails, fracture of bone structure, or screw pullout occurred. This study verified the safety and the accuracy of the individualized 3D printing screw insertion templates in the cervical spine as a kind of intraoperative screw navigation. This individualized 3D printing screw insertion template was user-friendly, moderate cost, and enabled a radiation-free cervical screw insertion.

Optimized functional femoral rotation in navigated total knee arthroplasty considering ligament tension.

PubMed

Walde, T A; Bussert, J; Sehmisch, S; Balcarek, P; Stürmer, K M; Walde, H J; Frosch, K H

2010-12-01

Femoral malrotation in total knee arthroplasty is correlated to an increased number of revisions. Anatomic landmarks such as Whiteside line, posterior condyle axis and transepicondylar axis are used for determining femoral component rotation. The femoral rotation achieved with the anatomical landmarks is compared to the femoral rotation achieved by a navigated ligament tension-based tibia-first technique. Ninety-three consecutive patients with gonarthritis were prospectively enrolled. Intraoperatively the anatomical landmarks for femoral rotation and the achieved femoral rotation using a navigated tension-based tibia-first technique were determined and stored for further comparison. A pre- and postoperative functional diagram displaying the extension and flexion and varus or valgus positions was also part of the evaluation. Using anatomical landmarks the rotational errors ranged from 12.2° of internal rotation to 15.5° of external rotation from parallel to the tibial resection surface at 90° flexion. A statistical significant improved femoral rotation was achieved using the ligament tension-based method with a rotational error ranged from 3.0° of internal rotation to 2.4° of external rotation. The functional analyses demonstrated statistical significant lower varus/valgus deviations within the flexion range and an improved maximum varus deviation at 90° flexion using the ligament tension-based method. Compared to the anatomical landmarks a balanced, almost parallel flexion gap was achieved using a navigation technique taking the ligament tension of the knee joint into account. As a result the improved femoral rotation was demonstrated by the functional evaluation. Unilateral overloading of the polyethylene inlay and unilateral instability can thus be avoided. Copyright © 2009 Elsevier B.V. All rights reserved.

SU-F-T-261: Reconstruction of Initial Photon Fluence Based On EPID Images

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

Seliger, T; Engenhart-Cabillic, R; Czarnecki, D

2016-06-15

Purpose: Verifying an algorithm to reconstruct relative initial photon fluence for clinical use. Clinical EPID and CT images were acquired to reconstruct an external photon radiation treatment field. The reconstructed initial photon fluence could be used to verify the treatment or calculate the applied dose to the patient. Methods: The acquired EPID images were corrected for scatter caused by the patient and the EPID with an iterative reconstruction algorithm. The transmitted photon fluence behind the patient was calculated subsequently. Based on the transmitted fluence the initial photon fluence was calculated using a back-projection algorithm which takes the patient geometry andmore » its energy dependent linear attenuation into account. This attenuation was gained from the acquired cone-beam CT or the planning CT by calculating a water-equivalent radiological thickness for each irradiation direction. To verify the algorithm an inhomogeneous phantom consisting of three inhomogeneities was irradiated by a static 6 MV photon field and compared to a reference flood field image. Results: The mean deviation between the reconstructed relative photon fluence for the inhomogeneous phantom and the flood field EPID image was 3% rising up to 7% for off-axis fluence. This was probably caused by the used clinical EPID calibration, which flattens the inhomogeneous fluence profile of the beam. Conclusion: In this clinical experiment the algorithm achieved good results in the center of the field while it showed high deviation of the lateral fluence. This could be reduced by optimizing the EPID calibration, considering the off-axis differential energy response. In further progress this and other aspects of the EPID, eg. field size dependency, CT and dose calibration have to be studied to realize a clinical acceptable accuracy of 2%.« less

Characterization of interfragmentary motion associated with common osteosynthesis devices for rat fracture healing studies.

PubMed

Meyers, Nicholaus; Sukopp, Matthias; Jäger, Rudolf; Steiner, Malte; Matthys, Romano; Lapatki, Bernd; Ignatius, Anita; Claes, Lutz

2017-01-01

Rat models are widely used in preclinical studies investigating fracture healing. The interfragmentary movement at a fracture site is critical to the course of healing and therefore demands definition in order to aptly interpret the experimental results. Estimation of this movement requires knowledge of the fixation stiffness and loading. The characteristic loading for the rat femur has been estimated, but the stiffness of fixation used in rat studies has yet to be fully described. This study aimed to determine the 6 degree of freedom stiffness of four commonly used implants, two external fixators (RatExFix and UlmExFix), a locking plate, and a locking intramedullary nail, in all degrees of freedom and estimate the interfragmentary movement under specific physiological loads. The external fixator systems allow the greatest movement. Mounted 45° anterolateral on the femur, the RatExFix allows an average of 0.88 mm of motion in each anatomic direction while the stiffer UlmExFix allows about 0.6 mm of motion. The nail is far stiffer than the other implants investigated while the plate allows movement of an intermediate magnitude. Both the nail and plate demonstrate higher axial than shear stiffness. The relatively large standard deviations in external fixator shear motion imply strong dependence on bone axis alignment across the gap and the precise orientation of the specimen relative to the loading. The smaller standard deviation associated with the nail and plate results from improved alignment and minimization of the influence of rotational positioning of the specimen due to the reduced implant eccentricity relative to the specimen axis. These results show that the interfragmentary movement is complex and varies significantly between fixation devices but establishes a baseline for the evaluation of the results of different studies.

Characterization of interfragmentary motion associated with common osteosynthesis devices for rat fracture healing studies

PubMed Central

Steiner, Malte; Matthys, Romano; Lapatki, Bernd; Ignatius, Anita; Claes, Lutz

2017-01-01

Rat models are widely used in preclinical studies investigating fracture healing. The interfragmentary movement at a fracture site is critical to the course of healing and therefore demands definition in order to aptly interpret the experimental results. Estimation of this movement requires knowledge of the fixation stiffness and loading. The characteristic loading for the rat femur has been estimated, but the stiffness of fixation used in rat studies has yet to be fully described. This study aimed to determine the 6 degree of freedom stiffness of four commonly used implants, two external fixators (RatExFix and UlmExFix), a locking plate, and a locking intramedullary nail, in all degrees of freedom and estimate the interfragmentary movement under specific physiological loads. The external fixator systems allow the greatest movement. Mounted 45° anterolateral on the femur, the RatExFix allows an average of 0.88 mm of motion in each anatomic direction while the stiffer UlmExFix allows about 0.6 mm of motion. The nail is far stiffer than the other implants investigated while the plate allows movement of an intermediate magnitude. Both the nail and plate demonstrate higher axial than shear stiffness. The relatively large standard deviations in external fixator shear motion imply strong dependence on bone axis alignment across the gap and the precise orientation of the specimen relative to the loading. The smaller standard deviation associated with the nail and plate results from improved alignment and minimization of the influence of rotational positioning of the specimen due to the reduced implant eccentricity relative to the specimen axis. These results show that the interfragmentary movement is complex and varies significantly between fixation devices but establishes a baseline for the evaluation of the results of different studies. PMID:28453556

The Impact of Mechanical and Restricted Kinematic Alignment on Knee Anatomy in Total Knee Arthroplasty.

PubMed

Almaawi, Abdulaziz M; Hutt, Jonathan R B; Masse, Vincent; Lavigne, Martin; Vendittoli, Pascal-Andre

2017-07-01

Total knee arthroplasty (TKA), aiming at neutral mechanical alignment (MA), inevitably modifies the patient's native knee anatomy. Another option is kinematic alignment (KA), which aims to restore the original anatomy of the knee. The aim of this study was to evaluate the variations in lower limb anatomy of a patient population scheduled for TKA, and to assess the use of a restricted KA TKA protocol and compare the resulting anatomic modifications with the standard MA technique. A total of 4884 knee computed tomography scans were analyzed from a database of patients undergoing TKA with patient-specific instrumentation. The lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and hip-knee-ankle angle (HKA) were measured. Bone resections were compared using a standard MA and a restricted KA aiming for independent tibial and femoral cuts of maximum ±5° deviation from the coronal mechanical axis and a resulting overall coronal HKA within ±3° of neutral. The mean preoperative MPTA was 2.9° varus, LDFA was 2.7° valgus, and overall HKA was 0.1° varus. Using our protocol, 2475 knees (51%) could have undergone KA without adjustment. To include 4062 cases (83%), mean corrections of 0.5° for MPTA and 0.3° for LDFA were needed, significantly less than with MA (3.3° for MPTA and 3.2° for LDFA; P < .001). The range of knee anatomy in patients scheduled for TKA is wide. MA leads to greater modifications of knee joint anatomy. To avoid reproducing extreme anatomy, the proposed restricted KA protocol provides an interesting hybrid option between MA and true KA. Copyright © 2017 Elsevier Inc. All rights reserved.

Heart Rate Reduction With Ivabradine Protects Against Left Ventricular Remodeling by Attenuating Infarct Expansion and Preserving Remote-Zone Contractile Function and Synchrony in a Mouse Model of Reperfused Myocardial Infarction.

PubMed

O'Connor, Daniel M; Smith, Robert S; Piras, Bryan A; Beyers, Ronald J; Lin, Dan; Hossack, John A; French, Brent A

2016-04-22

Ivabradine selectively inhibits the pacemaker current of the sinoatrial node, slowing heart rate. Few studies have examined the effects of ivabradine on the mechanical properties of the heart after reperfused myocardial infarction (MI). Advances in ultrasound speckle-tracking allow strain analyses to be performed in small-animal models, enabling the assessment of regional mechanical function. After 1 hour of coronary occlusion followed by reperfusion, mice received 10 mg/kg per day of ivabradine dissolved in drinking water (n=10), or were treated as infarcted controls (n=9). Three-dimensional high-frequency echocardiography was performed at baseline and at days 2, 7, 14, and 28 post-MI. Speckle-tracking software was used to calculate intramural longitudinal myocardial strain (Ell) and strain rate. Standard deviation time to peak radial strain (SD Tpeak Err) and temporal uniformity of strain were calculated from short-axis cines acquired in the left ventricular remote zone. Ivabradine reduced heart rate by 8% to 16% over the course of 28 days compared to controls (P<0.001). On day 28 post-MI, the ivabradine group was found to have significantly smaller end-systolic volumes, greater ejection fraction, reduced wall thinning, and greater peak Ell and Ell rate in the remote zone, as well as globally. Temporal uniformity of strain and SD Tpeak Err were significantly smaller in the ivabradine-treated group by day 28 (P<0.05). High-frequency ultrasound speckle-tracking demonstrated decreased left ventricular remodeling and dyssynchrony, as well as improved mechanical performance in remote myocardium after heart rate reduction with ivabradine. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Paleomagnetic and Seismologic Evidence for Oblique-Slip Partitioning to the Coalinga Anticline From the San Andreas Fault

NASA Astrophysics Data System (ADS)

Tetreault, J. L.; Jones, C. H.

2007-12-01

The Coalinga Anticline is a one of a series of fault-related folds in the central Coast Ranges, California, oriented subparallel to the San Andreas Fault (SAF). The development of the Central Coast Range anticlines can be related to the relative strength of the SAF. If positing a weak SAF, fault-normal slip is partitioned to these subparallel compressional folds. If the SAF is strong, these folds rotated to their current orientation during wrenching. Another possibility is that the Coast Range anticlines are accommodating oblique-slip partitioned from the SAF. The 1983 Coalinga earthquake does not have a purely thrusting focal mechanism (rake =100°), reflecting the likelihood that oblique slip is being partitioned to this anticline, even though surface expression of fold-axis-parallel slip has not been identified. Paleomagnetic vertical-axis rotations and focal mechanism strain inversions were used to quantify oblique-slip deformation within the Coalinga Anticline. Clockwise rotations of 10° to 16° are inferred from paleomagnetic sites located in late Miocene to Pliocene beds on the steeply dipping forelimb and backlimb of the fold. Significant vertical-axis rotations are not identified in the paleomagnetic sites within the nose of the anticline. The varying vertical axis rotations conflict with wrench tectonics (strong SAF) as the mechanism of fold development. We use focal mechanisms inversions of earthquakes that occurred between 1983 to 2006 to constrain the seismogenic strain within the fold that presumably help to build it over time. In the upper 7 km, the principal shortening axis is oriented N37E to N40E, statistically indistinguishable from normal to the fold (N45E). The right-lateral shear in the folded strata above the fault tip, evident from the paleomagnetically determined clockwise vertical-axis rotations, is being accommodated aseismically or interseismically. In the region between 7 and 11 km, where the mainshock occurred, the shortening direction ranges from oblique to normal to the fold trend. Our results show that right-lateral slip is resolved along the main fault plane and not distributed to the smaller aftershocks at depths of 7-11 km. The principal strain axes and clockwise paleomagnetic rotations indicate that the Coalinga Anticline is accommodating minor right-lateral shearing and thus shares some of the strike-slip motion of the San Andreas system.

Sound stress-induced long-term enhancement of mechanical hyperalgesia in rats is maintained by sympathoadrenal catecholamines.

PubMed

Khasar, Sachia G; Dina, Olayinka A; Green, Paul G; Levine, Jon D

2009-10-01

Although stress plays an important role in chronic widespread pain syndromes, such as fibromyalgia, the underlying mechanism has remained elusive. We have recently demonstrated, in a model of chronic widespread pain, that prolonged enhancement of immune mediator hyperalgesia, induced by unpredictable sound stress, requires a contribution of both the sympathoadrenal (epinephrine) and the hypothalamic-pituitary adrenal (corticosterone) neuroendocrine stress axes. Because this stress protocol produced sustained elevation of plasma epinephrine, in the current study we tested the hypothesis that the sympathoadrenal axis also plays a role in maintenance of symptoms in this model of chronic widespread pain. After establishment, adrenal medullectomy abolished the enhancement of epinephrine-induced cutaneous and muscle hyperalgesia. Administration of stress levels of epinephrine to adrenal medullectomized rats reconstituted the pain phenotype. These observations suggest that the sympathoadrenal stress axis plays a major role in the induction as well as maintenance of stress-induced enhancement of mechanical hyperalgesia, mediated by prolonged elevation of circulating epinephrine. We present data showing mechanical hyperalgesia persisting for up to 28 days after exposure to sound stress, with evidence that the sympathoadrenal axis mediator epinephrine plays a major role. These findings could have clinical implications with regard to novel potential treatments for chronic widespread pain syndromes, such as fibromyalgia.

From the Law of Large Numbers to Large Deviation Theory in Statistical Physics: An Introduction

NASA Astrophysics Data System (ADS)

Cecconi, Fabio; Cencini, Massimo; Puglisi, Andrea; Vergni, Davide; Vulpiani, Angelo

This contribution aims at introducing the topics of this book. We start with a brief historical excursion on the developments from the law of large numbers to the central limit theorem and large deviations theory. The same topics are then presented using the language of probability theory. Finally, some applications of large deviations theory in physics are briefly discussed through examples taken from statistical mechanics, dynamical and disordered systems.

76 FR 69632 - Drawbridge Operation Regulation; Calcasieu River, Westlake, LA

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-09

... deviation from the regulation governing the operation of the Union Pacific Railroad swing bridge across the... the electrical and mechanical systems of the bridge. This deviation allows the bridge to remain closed..., Docket Operations, telephone (202) 366-9826. SUPPLEMENTARY INFORMATION: The Union Pacific Railroad has...

Publisher Correction: Polymorphic design of DNA origami structures through mechanical control of modular components.

PubMed

Lee, Chanseok; Lee, Jae Young; Kim, Do-Nyun

2018-02-07

The originally published version of this Article contained an error in Figure 5. In panel f, the right y-axis 'Strain energy (kbT)' was labelled 'Probability' and the left y-axis 'Probability' was labelled 'Strain energy (kbT)'. This error has now been corrected in both the PDF and HTML versions of the Article.

Method and sample spinning apparatus for measuring the NMR spectrum of an orientationally disordered sample

DOEpatents

Pines, Alexander; Samoson, Ago

1990-01-01

An improved NMR apparatus and method are described which substantially improve the resolution of NMR measurements made on powdered or amorphous or otherwise orientationally disordered samples. The apparatus spins the sample about an axis. The angle of the axis is mechanically varied such that the time average of two or more Legendre polynomials are zero.

Mitotic cells generate protrusive extracellular forces to divide in three-dimensional microenvironments

NASA Astrophysics Data System (ADS)

Nam, Sungmin; Chaudhuri, Ovijit

2018-06-01

During mitosis, or cell division, mammalian cells undergo extensive morphological changes, including elongation along the mitotic axis, which is perpendicular to the plane that bisects the two divided cells. Although much is known about the intracellular dynamics of mitosis, it is unclear how cells are able to divide in tissues, where the changes required for mitosis are mechanically constrained by surrounding cells and extracellular matrix. Here, by confining cells three dimensionally in hydrogels, we show that dividing cells generate substantial protrusive forces that deform their surroundings along the mitotic axis, clearing space for mitotic elongation. When forces are insufficient to create space for mitotic elongation, mitosis fails. We identify one source of protrusive force as the elongation of the interpolar spindle, an assembly of microtubules aligned with the mitotic axis. Another source of protrusive force is shown to be contraction of the cytokinetic ring, the polymeric structure that cleaves a dividing cell at its equator, which drives expansion along the mitotic axis. These findings reveal key functions for the interpolar spindle and cytokinetic ring in protrusive extracellular force generation, and explain how dividing cells overcome mechanical constraints in confining microenvironments, including some types of tumour.

[A simulation study with finite element model on the unequal loss of peripheral vision caused by acceleration].

PubMed

Geng, Xiaoqi; Liu, Xiaoyu; Liu, Songyang; Xu, Yan; Zhao, Xianliang; Wang, Jie; Fan, Yubo

2017-04-01

An unequal loss of peripheral vision may happen with high sustaining multi-axis acceleration, leading to a great potential flight safety hazard. In the present research, finite element method was used to study the mechanism of unequal loss of peripheral vision. Firstly, a 3D geometric model of skull was developed based on the adult computer tomography (CT) images. The model of double eyes was created by mirroring with the previous right eye model. Then, the double-eye model was matched to the skull model, and fat was filled between eyeballs and skull. Acceleration loads of head-to-foot (G z ), right-to-left (G y ), chest-to-back (G x ) and multi-axis directions were applied to the current model to simulate dynamic response of retina by explicit dynamics solution. The results showed that the relative strain of double eyes was 25.7% under multi-axis acceleration load. Moreover, the strain distributions showed a significant difference among acceleration loaded in different directions. It indicated that a finite element model of double eyes was an effective means to study the mechanism of an unequal loss of peripheral vision at sustaining high multi-axis acceleration.

Early maternal separation followed by later stressors leads to dysregulation of the HPA-axis and increases in hippocampal NGF and NT-3 levels in a rat model.

PubMed

Faure, Jacqueline; Uys, Joachim D K; Marais, Lelanie; Stein, Dan J; Daniels, Willie M U

2006-09-01

Early adverse life events, followed by subsequent stressors, appear to increase susceptibility for subsequent onset of psychiatric disorders in humans. The molecular mechanisms that underlie this phenomenon remain unclear, but dysregulation of the HPA axis and alterations in neurotrophic factors have been implicated. The present study investigated the effects in rodents of early maternal separation, followed by stress in adolescence and adulthood on later HPA-axis activity and hippocampal neurotrophin levels (brain-derived neurotrophic factor, nerve growth factor, and neurotrophin-3). Animals subjected to repeated stressors showed a significant decrease in basal ACTH (p < 0.05) and CORT (p < 0.05) levels when compared to controls, as well as significantly increased levels of NGF in the dorsal (p < 0.001) and ventral hippocampus (p < 0.01), and of NT-3 in the dorsal hippocampus (p < 0.01). Dysregulation of the HPA axis after multiple stressors is consistent with previous preclinical and clinical work. Given that neurotrophins are important in neuronal survival and plasticity, it is possible to speculate that their elevation reflects a compensatory mechanism.

Cellular and Molecular Mechanisms of Anterior Chamber-Associated Immune Deviation (ACAID): What We Have Learned from Knockout Mice

PubMed Central

Vendomèle, Julie; Khebizi, Quentin; Fisson, Sylvain

2017-01-01

Anterior chamber-associated immune deviation (ACAID) is a well-known phenomenon that can occur after an antigen is introduced without any danger signal into the anterior chamber of a murine eye. It is reported to lead to an antigen-specific immune deviation throughout the body. Despite the relatively little evidence of this phenomenon in humans, it has been suggested as a potential prophylactic strategy in allograft rejections and in several autoimmune diseases. Cellular and molecular mechanisms of ACAID have been explored in different murine models mainly as proofs of concept, first by direct analyses of immune components in normal immunocompetent settings and by cell transfer experiments. Later, use of knockout (KO) mice has helped considerably to decipher ACAID mechanisms. However, several factors raise questions about the reliability and validity of studies using KO murine models. This mini-review summarizes results obtained with KO mice and discusses their advantages, their potential weaknesses, and their potential methods for further progress. PMID:29250068

Electro-mechanical sine/cosine generator

NASA Technical Reports Server (NTRS)

Flagge, B. (Inventor)

1972-01-01

An electromechanical device for generating both sine and cosine functions is described. A motor rotates a cylinder about an axis parallel to and a slight distance from the central axis of the cylinder. Two noncontacting displacement sensing devices are placed ninety degrees apart, equal distances from the axis of rotation of the cylinder and short distances above the surface of cylinder. Each of these sensing devices produces an electrical signal proportional to the distance that it is away from the cylinder. Consequently, as the cylinder is rotated the outputs from the two sensing devices are the sine and cosine functions.

Two-axis tracking using translation stages for a lens-to-channel waveguide solar concentrator.

PubMed

Liu, Yuxiao; Huang, Ran; Madsen, Christi K

2014-10-20

A two-axis tracking scheme designed for <250x concentration realized by a single-axis mechanical tracker and a translation stage is discussed. The translation stage is used for adjusting positions for seasonal sun movement. It has two-dimensional x-y tracking instead of horizontal movement x-only. This tracking method is compatible with planar waveguide solar concentrators. A prototype system with 50x concentration shows >75% optical efficiency throughout the year in simulation and >65% efficiency experimentally. This efficiency can be further improved by the use of anti-reflection layers and a larger waveguide refractive index.

Enantioselective route to 5-methyl- and 5,7-dimethyl-6,7-dihydro-5H-dibenz[c,e]azepine: secondary amines with switchable axial chirality.

PubMed

Pira, Silvain L; Wallace, Timothy W; Graham, Jonathan P

2009-04-02

(-)-5-Methyl-6,7-dihydro-5H-dibenz[c,e]azepine 4, a new secondary amine featuring an axis-center stereochemical relay, was prepared enantioselectively from 2'-acetylbiphenyl-2-carboxylic acid, using (R)-2-phenylglycinol as an auxiliary for the control of both elements of chirality. The biaryl axis in 4 preferentially adopts the aS-configuration, with the methyl substituent pseudoequatorial, but conversion into the corresponding N-Boc derivative locks the axis into the aR-configuration, as predicted on the basis of molecular mechanics calculations.

Research on the unsteady hydrodynamic characteristics of vertical axis tidal turbine

NASA Astrophysics Data System (ADS)

Zhang, Xue-wei; Zhang, Liang; Wang, Feng; Zhao, Dong-ya; Pang, Cheng-yan

2014-03-01

The unsteady hydrodynamic characteristics of vertical axis tidal turbine are investigated by numerical simulation based on viscous CFD method. The starting mechanism of the turbine is revealed through analyzing the interaction of its motion and dynamics during starting process. The operating hydrodynamic characteristics of the turbine in wave-current condition are also explored by combining with the linear wave theory. According to possible magnification of the cyclic loads in the maximum power tracking control of vertical axis turbine, a novel torque control strategy is put forward, which can improve the structural characteristics significantly without effecting energy efficiency.

Unsteady aerodynamic forces and torques on falling parallelograms in coupled tumbling-helical motions

NASA Astrophysics Data System (ADS)

Varshney, Kapil; Chang, Song; Wang, Z. Jane

2013-05-01

Falling parallelograms exhibit coupled motion of autogyration and tumbling, similar to the motion of falling tulip seeds, unlike maple seeds which autogyrate but do not tumble, or rectangular cards which tumble but do not gyrate. This coupled tumbling and autogyrating motion are robust, when card parameters, such as aspect ratio, internal angle, and mass density, are varied. We measure the three-dimensional (3D) falling kinematics of the parallelograms and quantify their descending speed, azimuthal rotation, tumbling rotation, and cone angle in each falling. The cone angle is insensitive to the variation of the card parameters, and the card tumbling axis does not overlap with but is close to the diagonal axis. In addition to this connection to the dynamics of falling seeds, these trajectories provide an ideal set of data to analyze 3D aerodynamic force and torque at an intermediate range of Reynolds numbers, and the results will be useful for constructing 3D aerodynamic force and torque models. Tracking these free falling trajectories gives us a nonintrusive method for deducing instantaneous aerodynamic forces. We determine the 3D aerodynamic forces and torques based on Newton-Euler equations. The dynamical analysis reveals that, although the angle of attack changes dramatically during tumbling, the aerodynamic forces have a weak dependence on the angle of attack. The aerodynamic lift is dominated by the coupling of translational and rotational velocities. The aerodynamic torque has an unexpectedly large component perpendicular to the card. The analysis of the Euler equation suggests that this large torque is related to the deviation of the tumbling axis from the principle axis of the card.

Unsteady aerodynamic forces and torques on falling parallelograms in coupled tumbling-helical motions.

PubMed

Varshney, Kapil; Chang, Song; Wang, Z Jane

2013-05-01

Falling parallelograms exhibit coupled motion of autogyration and tumbling, similar to the motion of falling tulip seeds, unlike maple seeds which autogyrate but do not tumble, or rectangular cards which tumble but do not gyrate. This coupled tumbling and autogyrating motion are robust, when card parameters, such as aspect ratio, internal angle, and mass density, are varied. We measure the three-dimensional (3D) falling kinematics of the parallelograms and quantify their descending speed, azimuthal rotation, tumbling rotation, and cone angle in each falling. The cone angle is insensitive to the variation of the card parameters, and the card tumbling axis does not overlap with but is close to the diagonal axis. In addition to this connection to the dynamics of falling seeds, these trajectories provide an ideal set of data to analyze 3D aerodynamic force and torque at an intermediate range of Reynolds numbers, and the results will be useful for constructing 3D aerodynamic force and torque models. Tracking these free falling trajectories gives us a nonintrusive method for deducing instantaneous aerodynamic forces. We determine the 3D aerodynamic forces and torques based on Newton-Euler equations. The dynamical analysis reveals that, although the angle of attack changes dramatically during tumbling, the aerodynamic forces have a weak dependence on the angle of attack. The aerodynamic lift is dominated by the coupling of translational and rotational velocities. The aerodynamic torque has an unexpectedly large component perpendicular to the card. The analysis of the Euler equation suggests that this large torque is related to the deviation of the tumbling axis from the principle axis of the card.

Alignment of the lower extremity mechanical axis by computer-aided design and application in total knee arthroplasty.

PubMed

Zhang, Yuan Z; Lu, Sheng; Zhang, Hui Q; Jin, Zhong M; Zhao, Jian M; Huang, Jian; Zhang, Zhi F

2016-10-01

The success of total knee arthroplasty (TKA) depends on many factors. The position of a prosthesis is vitally important. The purpose of the present study was to evaluate the value of a computer-aided establishing lower extremity mechanical axis in TKA using digital technology. A total of 36 cases of patients with TKA were randomly divided into the computer-aided design of navigation template group (NT) and conventional intramedullary positioning group (CIP). Three-dimensional (3D) CT scanning images of the hip, knee, and ankle were obtained in NT group. X-ray images and CT scans were transferred into the 3D reconstruction software. A 3D bone model of the hip, knee, ankle, as well as the modified loading, was reconstructed and saved in a stereolithographic format. In the 3D reconstruction model, the mechanical axis of the lower limb was determined, and the navigational templates produced an accurate model using a rapid prototyping technique. The THA in CIP group was performed according to a routine operation. CT scans were performed postoperatively to evaluate the accuracy of the two TKA methods. The averaged operative time of the NT group procedures was [Formula: see text] min shorter than those of the conventional procedures ([Formula: see text]  min). The coronal femoral angle, coronal tibial angle, posterior tibial slope were [Formula: see text], [Formula: see text], [Formula: see text] in NT group and [Formula: see text], [Formula: see text], [Formula: see text] in CIP group, respectively. Statistically significant group differences were found. The navigation template produced through mechanical axis of lower extremity may provide a relative accurate and simple method for TKA.

Validity of measurement of shear modulus by ultrasound shear wave elastography in human pennate muscle.

PubMed

Miyamoto, Naokazu; Hirata, Kosuke; Kanehisa, Hiroaki; Yoshitake, Yasuhide

2015-01-01

Ultrasound shear wave elastography is becoming a valuable tool for measuring mechanical properties of individual muscles. Since ultrasound shear wave elastography measures shear modulus along the principal axis of the probe (i.e., along the transverse axis of the imaging plane), the measured shear modulus most accurately represents the mechanical property of the muscle along the fascicle direction when the probe's principal axis is parallel to the fascicle direction in the plane of the ultrasound image. However, it is unclear how the measured shear modulus is affected by the probe angle relative to the fascicle direction in the same plane. The purpose of the present study was therefore to examine whether the angle between the principal axis of the probe and the fascicle direction in the same plane affects the measured shear modulus. Shear modulus in seven specially-designed tissue-mimicking phantoms, and in eleven human in-vivo biceps brachii and medial gastrocnemius were determined by using ultrasound shear wave elastography. The probe was positioned parallel or 20° obliquely to the fascicle across the B-mode images. The reproducibility of shear modulus measurements was high for both parallel and oblique conditions. Although there was a significant effect of the probe angle relative to the fascicle on the shear modulus in human experiment, the magnitude was negligibly small. These findings indicate that the ultrasound shear wave elastography is a valid tool for evaluating the mechanical property of pennate muscles along the fascicle direction.

Chronic Exposure of Marine Medaka (Oryzias melastigma) to 4,5-Dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) Reveals Its Mechanism of Action in Endocrine Disruption via the Hypothalamus-Pituitary-Gonadal-Liver (HPGL) Axis.

PubMed

Chen, Lianguo; Zhang, Weipeng; Ye, Rui; Hu, Chenyan; Wang, Qiangwei; Seemann, Frauke; Au, Doris W T; Zhou, Bingsheng; Giesy, John P; Qian, Pei-Yuan

2016-04-19

In this study, marine medaka (Oryzias melastigma) were chronically exposed for 28 days to environmentally realistic concentrations of 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) (0, 0.76, 2.45, and 9.86 μg/L), the active ingredient in commercial antifouling agent SeaNine 211. Alterations of the hypothalamus-pituitary-gonadal-liver (HPGL) axis were investigated across diverse levels of biological organization to reveal the underlying mechanisms of its endocrine disruptive effects. Gene transcription analysis showed that DCOIT had positive regulatory effects mainly in male HPGL axis with lesser extent in females. The stimulated steroidogenic activities resulted in increased concentrations of steroid hormones, including estradiol (E2), testosterone (T), and 11-KT-testosterone (11-KT), in the plasma of both sexes, leading to an imbalance in hormone homeostasis and increased E2/T ratio. The relatively estrogenic intracellular environment in both sexes induced the hepatic synthesis and increased the liver and plasma content of vitellogenin (VTG) or choriogenin. Furthermore, parental exposure to DCOIT transgenerationally impaired the viability of offspring, as supported by a decrease in hatching and swimming activity. Overall, the present results elucidated the estrogenic mechanisms along HPGL axis for the endocrine disruptive effects of DCOIT. The reproductive impairments of DCOIT at environmentally realistic concentrations highlights the need for more comprehensive investigations of its potential ecological risks.

The power grid AGC frequency bias coefficient online identification method based on wide area information

NASA Astrophysics Data System (ADS)

Wang, Zian; Li, Shiguang; Yu, Ting

2015-12-01

This paper propose online identification method of regional frequency deviation coefficient based on the analysis of interconnected grid AGC adjustment response mechanism of regional frequency deviation coefficient and the generator online real-time operation state by measured data through PMU, analyze the optimization method of regional frequency deviation coefficient in case of the actual operation state of the power system and achieve a more accurate and efficient automatic generation control in power system. Verify the validity of the online identification method of regional frequency deviation coefficient by establishing the long-term frequency control simulation model of two-regional interconnected power system.

Association between Mastication, the Hippocampus, and the HPA Axis: A Comprehensive Review.

PubMed

Azuma, Kagaku; Zhou, Qian; Niwa, Masami; Kubo, Kin-Ya

2017-08-03

Mastication is mainly involved in food intake and nutrient digestion with the aid of teeth. Mastication is also important for preserving and promoting general health, including hippocampus-dependent cognition. Both animal and human studies indicate that mastication influences hippocampal functions through the end product of the hypothalamic-pituitary-adrenal (HPA) axis, glucocorticoid (GC). Epidemiologic studies suggest that masticatory dysfunction in aged individuals, such as that resulting from tooth loss and periodontitis, acting as a source of chronic stress, activates the HPA axis, leading to increases in circulating GCs and eventually inducing various physical and psychological diseases, such as cognitive impairment, cardiovascular disorders, and osteoporosis. Recent studies demonstrated that masticatory stimulation or chewing during stressful conditions suppresses the hyperactivity of the HPA axis via GCs and GC receptors within the hippocampus, and ameliorates chronic stress-induced hippocampus-dependent cognitive deficits. Here, we provide a comprehensive overview of current research regarding the association between mastication, the hippocampus, and HPA axis activity. We also discuss several potential molecular mechanisms involved in the interactions between mastication, hippocampal function, and HPA axis activity.

Association between Mastication, the Hippocampus, and the HPA Axis: A Comprehensive Review

PubMed Central

Azuma, Kagaku; Zhou, Qian; Niwa, Masami; Kubo, Kin-ya

2017-01-01

Mastication is mainly involved in food intake and nutrient digestion with the aid of teeth. Mastication is also important for preserving and promoting general health, including hippocampus-dependent cognition. Both animal and human studies indicate that mastication influences hippocampal functions through the end product of the hypothalamic-pituitary-adrenal (HPA) axis, glucocorticoid (GC). Epidemiologic studies suggest that masticatory dysfunction in aged individuals, such as that resulting from tooth loss and periodontitis, acting as a source of chronic stress, activates the HPA axis, leading to increases in circulating GCs and eventually inducing various physical and psychological diseases, such as cognitive impairment, cardiovascular disorders, and osteoporosis. Recent studies demonstrated that masticatory stimulation or chewing during stressful conditions suppresses the hyperactivity of the HPA axis via GCs and GC receptors within the hippocampus, and ameliorates chronic stress-induced hippocampus-dependent cognitive deficits. Here, we provide a comprehensive overview of current research regarding the association between mastication, the hippocampus, and HPA axis activity. We also discuss several potential molecular mechanisms involved in the interactions between mastication, hippocampal function, and HPA axis activity. PMID:28771175

Why the long face? The importance of vertical image structure for biological "barcodes" underlying face recognition.

PubMed

Spence, Morgan L; Storrs, Katherine R; Arnold, Derek H

2014-07-29

Humans are experts at face recognition. The mechanisms underlying this complex capacity are not fully understood. Recently, it has been proposed that face recognition is supported by a coarse-scale analysis of visual information contained in horizontal bands of contrast distributed along the vertical image axis-a biological facial "barcode" (Dakin & Watt, 2009). A critical prediction of the facial barcode hypothesis is that the distribution of image contrast along the vertical axis will be more important for face recognition than image distributions along the horizontal axis. Using a novel paradigm involving dynamic image distortions, a series of experiments are presented examining famous face recognition impairments from selectively disrupting image distributions along the vertical or horizontal image axes. Results show that disrupting the image distribution along the vertical image axis is more disruptive for recognition than matched distortions along the horizontal axis. Consistent with the facial barcode hypothesis, these results suggest that human face recognition relies disproportionately on appropriately scaled distributions of image contrast along the vertical image axis. © 2014 ARVO.

Anisotropic ionizing radiation in Seyfert galaxies. I - The extended narrow-line region in Markarian 573

NASA Technical Reports Server (NTRS)

Tsvetanov, Zlatan; Walsh, J. R.

1992-01-01

The morphology, kinematics, and ionization state of the nuclear extended narrow-line region (ENLR) of the Seyfert 2 galaxy Mrk 573 are studied using narrow-band images of a grid of long-slit spectra. The entire ENLR is mapped spectroscopically, and velocity structure is studied. The velocity field map shows a typical galactic rotation picture with some important deviations. A simple geometric model, in accordance with the 'unified schemes', is employed to study the effects of various parameters of the observed picture. The best match is achieved when a biconical radiation field illuminates the ISM of the host galaxy that takes part in a normal galaxy rotation but also has radial motions close to the nucleus. The emission-line images reveal an ENLR elongated along the radio axis in the northwest-southeast direction, but a map of the flux ratio forbidden O III 5007/(H-alpha + forbidden N II) shows a different structure, with the highest excitation peak offset by about 4 arcsec along the radio axis to the southeast.

From bicycle chain ring shape to gear ratio: algorithm and examples.

PubMed

van Soest, A J

2014-01-03

A simple model of the bicycle drive system with a non-circular front chain ring is proposed and an algorithm is devised for calculation of the corresponding Gear Ratio As a Function Of Crank Angle (GRAFOCA). It is shown that the true effective radius of the chain ring is always the perpendicular distance between the crank axis and the line through the chain segment between the chain ring and the cog. It is illustrated that the true effective radius of the chain ring at any crank angle may differ substantially from the maximum vertical distance between the crank axis and the chain ring circumference that is used as a proxy for the effective chain ring radius in several studies; in particular, the crank angle at which the effective chain ring radius is maximal as predicted from the latter approach may deviate by as much as 0.30 rad from the true value. The algorithm proposed may help in designing chain rings that achieve the desired GRAFOCA. © 2013 Published by Elsevier Ltd. All rights reserved.

Crystal structure of benzyl 3-(3-methyl-phen-yl)di-thio-carbazate.

PubMed

Aziz, NurFadhilah Abdul; Yusof, Enis Nadia Md; Ravoof, Thahira Begum S A; Tiekink, Edward R T

2015-04-01

In the title compound, C15H16N2S2, the central CN2S2 residue is almost planar (r.m.s. deviation = 0.0354 Å) and forms dihedral angles of 56.02 (4) and 75.52 (4)° with the phenyl and tolyl rings, respectively; the dihedral angle between the aromatic rings is 81.72 (5)°. The conformation about the N-N bond is gauche [C-N-N-C = -117.48 (15)°]. Overall, the mol-ecule has the shape of the letter L. In the crystal packing, supra-molecular chains along the a axis are formed by N-H⋯S(thione) hydrogen bonds whereby the thione S atom accepts two such bonds. The hydrogen bonding leads to alternating edge-shared eight-membered {⋯HNCS}2 and 10-membered {⋯HNNH⋯S}2 synthons. The chains are connected into layers by phen-yl-tolyl C-H⋯π inter-actions; the layers stack along the c axis with no specific inter-actions between them.

Relation between perception of vertical axis rotation and vestibulo-ocular reflex symmetry

NASA Technical Reports Server (NTRS)

Peterka, Robert J.; Benolken, Martha S.

1991-01-01

Subjects seated in a vertical axis rotation chair controlled their rotational velocity by adjusting a potentiometer. Their goal was to null out pseudorandom rotational perturbations in order to remain perceptually stationary. Most subjects showed a slow linear drift of velocity (a constant acceleration) to one side when they were deprived of an earth-fixed visual reference. The amplitude and direction of this drift can be considered a measure of a static bias in the subject's perception of rotation. The presence of a perceptual bias is consistent with a small, constant imbalance of vestibular function which could be of either central or peripheral origin. Deviations from perfect vestibulocular reflex (VOR) symmetry are also assumed to be related to imbalances in either peripheral or central vestibular function. Researchers looked for correlations between perceptual bias and various measures of vestibular reflex symmetry that might suggest a common source for both reflective and perceptual imbalances. No correlations were found. Measurement errors could not account for these results since repeated tests on the same subjects of both perceptual bias and VOR symmetry were well correlated.

Error analysis and experiments of attitude measurement using laser gyroscope

NASA Astrophysics Data System (ADS)

Ren, Xin-ran; Ma, Wen-li; Jiang, Ping; Huang, Jin-long; Pan, Nian; Guo, Shuai; Luo, Jun; Li, Xiao

2018-03-01

The precision of photoelectric tracking and measuring equipment on the vehicle and vessel is deteriorated by the platform's movement. Specifically, the platform's movement leads to the deviation or loss of the target, it also causes the jitter of visual axis and then produces image blur. In order to improve the precision of photoelectric equipment, the attitude of photoelectric equipment fixed with the platform must be measured. Currently, laser gyroscope is widely used to measure the attitude of the platform. However, the measurement accuracy of laser gyro is affected by its zero bias, scale factor, installation error and random error. In this paper, these errors were analyzed and compensated based on the laser gyro's error model. The static and dynamic experiments were carried out on a single axis turntable, and the error model was verified by comparing the gyro's output with an encoder with an accuracy of 0.1 arc sec. The accuracy of the gyroscope has increased from 7000 arc sec to 5 arc sec for an hour after error compensation. The method used in this paper is suitable for decreasing the laser gyro errors in inertial measurement applications.

Mechanical adaptability of the Bouligand-type structure in natural dermal armour.

PubMed

Zimmermann, Elizabeth A; Gludovatz, Bernd; Schaible, Eric; Dave, Neil K N; Yang, Wen; Meyers, Marc A; Ritchie, Robert O

2013-01-01

Arapaima gigas, a fresh water fish found in the Amazon Basin, resist predation by piranhas through the strength and toughness of their scales, which act as natural dermal armour. Arapaima scales consist of a hard, mineralized outer shell surrounding a more ductile core. This core region is composed of aligned mineralized collagen fibrils arranged in distinct lamellae. Here we show how the Bouligand-type (twisted plywood) arrangement of collagen fibril lamellae has a key role in developing their unique protective properties, by using in situ synchrotron small-angle X-ray scattering during mechanical tensile tests to observe deformation mechanisms in the fibrils. Specifically, the Bouligand-type structure allows the lamellae to reorient in response to the loading environment; remarkably, most lamellae reorient towards the tensile axis and deform in tension through stretching/sliding mechanisms, whereas other lamellae sympathetically rotate away from the tensile axis and compress, thereby enhancing the scale's ductility and toughness to prevent fracture.

Pilots strategically compensate for display enlargements in surveillance and flight control tasks.

PubMed

Stelzer, Emily Muthard; Wickens, Christopher D

2006-01-01

Experiments were conducted to assess the impact of display size on flight control, airspace surveillance, and goal-directed target search. Research of 3-D displays has shown that display scale compression influences the perception of flight path deviation, though less is known about the causes that drive this effect. In addition, research on attention-based tasks has shown that information displaced to significant eccentricities can amplify effort, but it is unclear whether the effect generates a performance difference in complex displays. In Experiment 1, 16 pilots completed a low-fidelity flight control task under single- and dual-axis control. In Experiment 2, the control task from Experiment 1 was scaled up to a more realistic flight environment, and pilots performed hazard surveillance and target search tasks. For flight control, pilots exhibited less path error and greater stick activity with a large display, which was attributed both to greater enhanced resolution and to the fact that larger depictions of error lead to greater urgency in correcting deviations. Size did not affect hazard surveillance or search, as pilots were adaptive in altering scanning patterns in response to the enlargement of the displays. Although pilots were adaptive to display changes in search and surveillance, display size reduction diminished estimates of flight path deviation and control performance because of lowered resolution and control urgency. Care should be taken when manipulating display size, as size reduction can diminish control performance.

Design and fabrication of nosecone for WB-57F aircraft fitted with APQ-102A side looking radar

NASA Technical Reports Server (NTRS)

1977-01-01

The design, fabrication, and testing of a nose cone which included a radome for a NASA WB-57F high altitude natural resources mapping aircraft was reviewed. The plane was fitted with a APQ-102A side looking radar operating at 9.6 GHz. The radar is directed normally to the direction of the flight and downward by a changeable angle, and it is assumed that the axis of the plane will not deviate from this direction by more than + or - 6 deg. The radome is required to subtend an angle of 160 deg centered 30 deg below the left horizon.

Solar Tracking Error Analysis of Fresnel Reflector

PubMed Central

Zheng, Jiantao; Yan, Junjie; Pei, Jie; Liu, Guanjie

2014-01-01

Depending on the rotational structure of Fresnel reflector, the rotation angle of the mirror was deduced under the eccentric condition. By analyzing the influence of the sun tracking rotation angle error caused by main factors, the change rule and extent of the influence were revealed. It is concluded that the tracking errors caused by the difference between the rotation axis and true north meridian, at noon, were maximum under certain conditions and reduced at morning and afternoon gradually. The tracking error caused by other deviations such as rotating eccentric, latitude, and solar altitude was positive at morning, negative at afternoon, and zero at a certain moment of noon. PMID:24895664

The electrocardiogram of athletes Comparison with untrained subjects1

PubMed Central

Van Ganse, W.; Versee, L.; Eylenbosch, W.; Vuylsteek, K.

1970-01-01

The resting electrocardiograms of 30 cyclists currently involved in competitive sport were compared with those of an equal number of healthy controls matched for age, height, and weight. The cyclists had significantly lower heart rates, longer PQ,QRS, and QTc intervals, higher T waves in lead II, left axis deviation of the T wave, higher R waves in the right and deeper S waves in the left praecordial leads, and deeper S waves in the right and higher R waves in the left praecordial leads. The possible significance of these findings should be assessed by prolonged prospective studies in athletes and untrained control subjects. PMID:4245411

Benzil bis­(ketazine)

PubMed Central

Patra, Goutam Kumar; Mukherjee, Anindita; Ng, Seik Weng

2009-01-01

The title compound (systematic name: 1,1′,2,2′-tetra­phenyl-2,2′-azinodiethanone), C28H20N2O2, was obtained by the reaction of benzil monohydrazone with chromium(III) nitrate. The dibenzyl­idene hydrazine unit is nearly planar (r.m.s. deviation = 0.073 Å) and the two benzoyl units are oriented almost perpendicular to it [dihedral angle = 87.81 (2), 87.81 (2)°]. The mol­ecules are linked into chains along the c axis by C—H⋯O hydrogen bonds and the chains are cross-linked via C—H⋯π inter­actions involving the benzoyl phenyl rings. PMID:21583456

Effect of Off-Axis Screw Insertion, Insertion Torque, and Plate Contouring on Locked Screw Strength

PubMed Central

Gallagher, Bethany; Silva, Matthew J.; Ricci, William M.

2015-01-01

Objectives This study quantifies the effects of insertion torque, off-axis screw angulation, and plate contouring on the strength of locking plate constructs. Methods Groups of locking screws (n = 6–11 screws) were inserted at 50%, 100%, 150%, and 200% of the manufacturer-recommended torque (3.2 Nm) into locking compression plates at various angles: orthogonal (control), 5-degree angle off-axis, and 10-degree angle off-axis. Screws were loaded to failure by a transverse force (parallel to the plate) either in the same (“+”) or opposite direction (“−”) of the initial screw angulation. Separately, locking plates were bent to 5 and 10-degree angles, with the bend apex at a screw hole. Locking screws inserted orthogonally into the apex hole at 100% torque were loaded to failure. Results Orthogonal insertion resulted in the highest average load to failure, 2577 ± 141 N (range, 2413–2778 N), whereas any off-axis insertion significantly weakened constructs (165–1285 N, at 100% torque) (P < 0.05). For “+” loading, torque beyond 100% did not increase strength, but 50% torque reduced screw strength (P < 0.05). Loading in the “−” direction consistently resulted in higher strengths than “+” loading (P < 0.05). Plate contouring of 5-degree angle did not significantly change screw strength compared with straight plates but contouring of 10-degree angle significantly reduced load to failure (P < 0.05). Conclusions To maximize the screw plate interface strength, locking screws should be inserted without cross-threading. The mechanical stability of locked screws is significantly compromised by loose insertion, off-axis insertion, or severe distortion of the locking mechanism. PMID:24343255

Mechanism of anisotropic surface self-diffusivity at the prismatic ice-vapor interface.

PubMed

Gladich, Ivan; Oswald, Amrei; Bowens, Natalie; Naatz, Sam; Rowe, Penny; Roeselova, Martina; Neshyba, Steven

2015-09-21

Predictive theoretical models for mesoscopic roughening of ice require improved understanding of attachment kinetics occurring at the ice-vapor interface. Here, we use classical molecular dynamics to explore the generality and mechanics of a transition from anisotropic to isotropic self-diffusivity on exposed prismatic surfaces. We find that self-diffusion parallel to the crystallographic a-axis is favored over the c-axis at sub-melt temperatures below about -35 °C, for three different representations of the water-water intermolecular potential. In the low-temperature anisotropic regime, diffusion results from interstitial admolecules encountering entropically distinct barriers to diffusion in the two in-plane directions. At higher temperatures, isotropic self-diffusion occurring deeper within the quasi-liquid layer becomes the dominant mechanism, owing to its larger energy of activation.

Laser device

DOEpatents

Scott, Jill R.; Tremblay, Paul L.

2008-08-19

A laser device includes a virtual source configured to aim laser energy that originates from a true source. The virtual source has a vertical rotational axis during vertical motion of the virtual source and the vertical axis passes through an exit point from which the laser energy emanates independent of virtual source position. The emanating laser energy is collinear with an orientation line. The laser device includes a virtual source manipulation mechanism that positions the virtual source. The manipulation mechanism has a center of lateral pivot approximately coincident with a lateral index and a center of vertical pivot approximately coincident with a vertical index. The vertical index and lateral index intersect at an index origin. The virtual source and manipulation mechanism auto align the orientation line through the index origin during virtual source motion.

Stirling engine control mechanism and method

DOEpatents

Dineen, John J.

1983-01-01

A reciprocating-to-rotating motion conversion and power control device for a Stirling engine includes a hub mounted on an offset portion of the output shaft for rotation relative to the shaft and for sliding motion therealong which causes the hub to tilt relative to the axis of rotation of the shaft. This changes the angle of inclination of the hub relative to the shaft axis and changes the axial stroke of a set of arms connected to the hub and nutating therewith. A hydraulic actuating mechanism is connected to the hub for moving its axial position along the shaft. A balancing wheel is linked to the hub and changes its angle of inclination as the angle of inclination of the hub changes to maintain the mechanism in perfect balance throughout its range of motion.

Prenatal Maternal Stress Predicts Methylation of Genes Regulating the Hypothalamic-Pituitary-Adrenocortical System in Mothers and Newborns in the Democratic Republic of Congo

ERIC Educational Resources Information Center

Kertes, Darlene A.; Kamin, Hayley S.; Hughes, David A.; Rodney, Nicole C.; Bhatt, Samarth; Mulligan, Connie J.

2016-01-01

Exposure to stress early in life permanently shapes activity of the hypothalamic-pituitary-adrenocortical (HPA) axis and the brain. Prenatally, glucocorticoids pass through the placenta to the fetus with postnatal impacts on brain development, birth weight (BW), and HPA axis functioning. Little is known about the biological mechanisms by which…

Estimation of Nutation Time Constant Model Parameters for On-Axis Spinning Spacecraft

NASA Technical Reports Server (NTRS)

Schlee, Keith; Sudermann, James

2008-01-01

Calculating an accurate nutation time constant for a spinning spacecraft is an important step for ensuring mission success. Spacecraft nutation is caused by energy dissipation about the spin axis. Propellant slosh in the spacecraft fuel tanks is the primary source for this dissipation and can be simulated using a forced motion spin table. Mechanical analogs, such as pendulums and rotors, are typically used to simulate propellant slosh. A strong desire exists for an automated method to determine these analog parameters. The method presented accomplishes this task by using a MATLAB Simulink/SimMechanics based simulation that utilizes the Parameter Estimation Tool.

Two-axis antenna positioning mechanism

NASA Technical Reports Server (NTRS)

Herald, Michelle; Wai, Leilani C.

1994-01-01

The two-axis antenna positioning mechanism (TAAPM) is used to position three Ku-band and one C-band spot antennas on the INTELSAT 7 (I-7) spacecraft, which is a commercial telecommunications satellite purchased and operated by INTELSAT, an international consortium. The first I-7 was successfully launched on 22 Oct. 1993 from French Guiana on an Ariane launch vehicle. The TAAPM's on the first I-7 satellite successfully completed their in-orbit functional testing. The TAAPM was an entirely new design for Space Systems/Loral. This paper will describe the spacecraft/system requirements and application of the TAAPM and present the technical findings of TAAPM qualification and protoflight testing.

A mechanical rotator for neutron scattering measurements

DOE PAGES

Thaler, A.; Northen, E.; Aczel, A. A.; ...

2016-12-01

We have designed and built a mechanical rotation system for use in single crystal neutron scattering experiments at low temperatures. The main motivation for this device is to facilitate the application of magnetic fields transverse to a primary training axis, using only a vertical cryomagnet. Development was done in the context of a triple-axis neutron spectrometer, but the design is such that it can be generalized to a number of different instruments or measurement techniques. Here, we discuss some of the experimental constraints motivating the design, followed by design specifics, preliminary experimental results, and a discussion of potential uses andmore » future extension possibilities.« less

Viscoelastic properties of addition-cured polyimides used in high temperature polymer matrix composites

NASA Technical Reports Server (NTRS)

Roberts, Gary D.; Malarik, Diane C.; Robaidek, Jerrold O.

1991-01-01

The viscoelastic properties of an addition-cured polyimide, PMR-15, were evaluated through dynamic mechanical and stress relaxation testing. Below the glass transition temperature, the dynamic mechanical properties of the composites are strongly affected by the absorbed moisture in the resin. At temperature 20 C and more above the glass transition temperature, the storage modulus increases continuously with time, indicating that additional crosslinking is occurring in the resin. For resin moisture contents less than 2 percent, stress relaxation curves measured at different temperatures can be superimposed using horizontal shifts along the log(time) axis with only small shifts along the vertical axis.

ICESat-2 ATLAS Beam Steering Mechanism (BSM)

NASA Technical Reports Server (NTRS)

Hinkle, Matthew

2015-01-01

This work covers the design and test of a beam steering mechanism (BSM) used to accurately guide a laser on the Advanced Topographic Laser Altimeter System (ATLAS) down to Earth in order to measure elevation. It describes the main components in the BSM that allows it to perform and meet stringent requirements. Requirements of the BSM include two-axis steering of the transmitted laser beam, +-5000 uRad mechanical motion in each axis, and 1.5 uRad RMS pointing stability among many other requirements. The BSM uses four voice coil actuators in order to locate the mirror at the angle we need. There are four Differential Position Sensors that determine the position and angle of the mirror at all times. These sensors were verified through optical testing in both ambient and thermal conditions. Testing and extensive analyses were performed on the two-axis flexure throughout the program to check flexure thickness, positive margins, and infinite life. The mirror mount design has been modified to eliminate radial preload, while incorporating a titanium wave spring to provide an axial preload of 10.8N. The BSM underwent multiple tests in order to verify all components work as required under various conditions.

Mechanical Forces Program the Orientation of Cell Division during Airway Tube Morphogenesis.

PubMed

Tang, Zan; Hu, Yucheng; Wang, Zheng; Jiang, Kewu; Zhan, Cheng; Marshall, Wallace F; Tang, Nan

2018-02-05

Oriented cell division plays a key role in controlling organogenesis. The mechanisms for regulating division orientation at the whole-organ level are only starting to become understood. By combining 3D time-lapse imaging, mouse genetics, and mathematical modeling, we find that global orientation of cell division is the result of a combination of two types of spindles with distinct spindle dynamic behaviors in the developing airway epithelium. Fixed spindles follow the classic long-axis rule and establish their division orientation before metaphase. In contrast, rotating spindles do not strictly follow the long-axis rule and determine their division orientation during metaphase. By using both a cell-based mechanical model and stretching-lung-explant experiments, we showed that mechanical force can function as a regulatory signal in maintaining the stable ratio between fixed spindles and rotating spindles. Our findings demonstrate that mechanical forces, cell geometry, and oriented cell division function together in a highly coordinated manner to ensure normal airway tube morphogenesis. Copyright © 2017 Elsevier Inc. All rights reserved.

Patient-specific IMRT verification using independent fluence-based dose calculation software: experimental benchmarking and initial clinical experience.

PubMed

Georg, Dietmar; Stock, Markus; Kroupa, Bernhard; Olofsson, Jörgen; Nyholm, Tufve; Ahnesjö, Anders; Karlsson, Mikael

2007-08-21

Experimental methods are commonly used for patient-specific intensity-modulated radiotherapy (IMRT) verification. The purpose of this study was to investigate the accuracy and performance of independent dose calculation software (denoted as 'MUV' (monitor unit verification)) for patient-specific quality assurance (QA). 52 patients receiving step-and-shoot IMRT were considered. IMRT plans were recalculated by the treatment planning systems (TPS) in a dedicated QA phantom, in which an experimental 1D and 2D verification (0.3 cm(3) ionization chamber; films) was performed. Additionally, an independent dose calculation was performed. The fluence-based algorithm of MUV accounts for collimator transmission, rounded leaf ends, tongue-and-groove effect, backscatter to the monitor chamber and scatter from the flattening filter. The dose calculation utilizes a pencil beam model based on a beam quality index. DICOM RT files from patient plans, exported from the TPS, were directly used as patient-specific input data in MUV. For composite IMRT plans, average deviations in the high dose region between ionization chamber measurements and point dose calculations performed with the TPS and MUV were 1.6 +/- 1.2% and 0.5 +/- 1.1% (1 S.D.). The dose deviations between MUV and TPS slightly depended on the distance from the isocentre position. For individual intensity-modulated beams (total 367), an average deviation of 1.1 +/- 2.9% was determined between calculations performed with the TPS and with MUV, with maximum deviations up to 14%. However, absolute dose deviations were mostly less than 3 cGy. Based on the current results, we aim to apply a confidence limit of 3% (with respect to the prescribed dose) or 6 cGy for routine IMRT verification. For off-axis points at distances larger than 5 cm and for low dose regions, we consider 5% dose deviation or 10 cGy acceptable. The time needed for an independent calculation compares very favourably with the net time for an experimental approach. The physical effects modelled in the dose calculation software MUV allow accurate dose calculations in individual verification points. Independent calculations may be used to replace experimental dose verification once the IMRT programme is mature.

The apelin-APJ axis: A novel potential therapeutic target for organ fibrosis.

PubMed

Huang, Shifang; Chen, Linxi; Lu, Liqun; Li, Lanfang

2016-05-01

Apelin, an endogenous ligand of the G-protein-coupled receptor APJ, is expressed in a diverse number of organs. The apelin-APJ axis helps to control the processes of pathological and physiological fibrosis, including renal fibrosis, cardiac fibrosis, liver fibrosis and pulmonary fibrosis. However, the role of apelin-APJ in organ fibrosis remains controversial due to conflicting study results. The apelin-APJ axis is a detrimental mechanism which promotes liver fibrosis mainly via up-regulation the expression of collagen-II and platelet-derived growth factor receptor β (PDGFRβ). On the contrary, the apelin-APJ axis is beneficial for renal fibrosis, cardiac fibrosis and pulmonary fibrosis. The apelin-APJ axis alleviates renal fibrosis by restraining the expression of transforming growth factor-β1 (TGF-β1). In addition, the apelin-APJ axis attenuates cardiac fibrosis through multiple pathways. Furthermore, the apelin-APJ axis has beneficial effects on experimental bronchopulmonary dysplasia (BPD) and acute respiratory distress syndrome (ARDS) which suggest the apelin-APJ axis potentially alleviates pulmonary fibrosis. In this article, we review the controversies associated with apelin-APJ in organ fibrosis and introduce the drugs that target apelin-APJ. We conclude that future studies should place more emphasis on the relationship among apelin isoforms, APJ receptor subtypes and organ fibrosis. The apelin-APJ axis will be a potential therapeutic target and those drugs targeted for apelin-APJ may constitute a novel therapeutic strategy for renal fibrosis, cardiac fibrosis, liver fibrosis and pulmonary fibrosis. Copyright © 2016 Elsevier B.V. All rights reserved.

Hybrid shallow on-axis and deep off-axis hydrothermal circulation at fast-spreading ridges.

PubMed

Hasenclever, Jörg; Theissen-Krah, Sonja; Rüpke, Lars H; Morgan, Jason P; Iyer, Karthik; Petersen, Sven; Devey, Colin W

2014-04-24

Hydrothermal flow at oceanic spreading centres accounts for about ten per cent of all heat flux in the oceans and controls the thermal structure of young oceanic plates. It also influences ocean and crustal chemistry, provides a basis for chemosynthetic ecosystems, and has formed massive sulphide ore deposits throughout Earth's history. Despite this, how and under what conditions heat is extracted, in particular from the lower crust, remains largely unclear. Here we present high-resolution, whole-crust, two- and three-dimensional simulations of hydrothermal flow beneath fast-spreading ridges that predict the existence of two interacting flow components, controlled by different physical mechanisms, that merge above the melt lens to feed ridge-centred vent sites. Shallow on-axis flow structures develop owing to the thermodynamic properties of water, whereas deeper off-axis flow is strongly shaped by crustal permeability, particularly the brittle-ductile transition. About 60 per cent of the discharging fluid mass is replenished on-axis by warm (up to 300 degrees Celsius) recharge flow surrounding the hot thermal plumes, and the remaining 40 per cent or so occurs as colder and broader recharge up to several kilometres away from the axis that feeds hot (500-700 degrees Celsius) deep-rooted off-axis flow towards the ridge. Despite its lower contribution to the total mass flux, this deep off-axis flow carries about 70 per cent of the thermal energy released at the ridge axis. This combination of two flow components explains the seismically determined thermal structure of the crust and reconciles previously incompatible models favouring either shallower on-axis or deeper off-axis hydrothermal circulation.

The neural basis of financial risk taking.

PubMed

Kuhnen, Camelia M; Knutson, Brian

2005-09-01

Investors systematically deviate from rationality when making financial decisions, yet the mechanisms responsible for these deviations have not been identified. Using event-related fMRI, we examined whether anticipatory neural activity would predict optimal and suboptimal choices in a financial decision-making task. We characterized two types of deviations from the optimal investment strategy of a rational risk-neutral agent as risk-seeking mistakes and risk-aversion mistakes. Nucleus accumbens activation preceded risky choices as well as risk-seeking mistakes, while anterior insula activation preceded riskless choices as well as risk-aversion mistakes. These findings suggest that distinct neural circuits linked to anticipatory affect promote different types of financial choices and indicate that excessive activation of these circuits may lead to investing mistakes. Thus, consideration of anticipatory neural mechanisms may add predictive power to the rational actor model of economic decision making.

Stochastic assembly in a subtropical forest chronosequence: evidence from contrasting changes of species, phylogenetic and functional dissimilarity over succession.

PubMed

Mi, Xiangcheng; Swenson, Nathan G; Jia, Qi; Rao, Mide; Feng, Gang; Ren, Haibao; Bebber, Daniel P; Ma, Keping

2016-09-07

Deterministic and stochastic processes jointly determine the community dynamics of forest succession. However, it has been widely held in previous studies that deterministic processes dominate forest succession. Furthermore, inference of mechanisms for community assembly may be misleading if based on a single axis of diversity alone. In this study, we evaluated the relative roles of deterministic and stochastic processes along a disturbance gradient by integrating species, functional, and phylogenetic beta diversity in a subtropical forest chronosequence in Southeastern China. We found a general pattern of increasing species turnover, but little-to-no change in phylogenetic and functional turnover over succession at two spatial scales. Meanwhile, the phylogenetic and functional beta diversity were not significantly different from random expectation. This result suggested a dominance of stochastic assembly, contrary to the general expectation that deterministic processes dominate forest succession. On the other hand, we found significant interactions of environment and disturbance and limited evidence for significant deviations of phylogenetic or functional turnover from random expectations for different size classes. This result provided weak evidence of deterministic processes over succession. Stochastic assembly of forest succession suggests that post-disturbance restoration may be largely unpredictable and difficult to control in subtropical forests.

Interplay between type IV pili activity and exopolysaccharides secretion controls motility patterns in single cells of Myxococcus xanthus

PubMed Central

Hu, Wei; Gibiansky, Maxsim L.; Wang, Jing; Wang, Chuandong; Lux, Renate; Li, Yuezhong; Wong, Gerard C. L.; Shi, Wenyuan

2016-01-01

Myxococcus xanthus performs coordinated social motility of cell groups through the extension and retraction of type IV pili (TFP) on solid surfaces, which requires both TFP and exopolysaccharides (EPS). By submerging cells in a liquid medium containing 1% methylcellulose, M. xanthus TFP-driven motility was induced in isolated cells and independently of EPS. We measured and analyzed the movements of cells using community tracking algorithms, which combine single-cell resolution with statistics from large sample populations. Cells without significant multi-cellular social interactions have surprisingly complex behaviors: EPS− cells exhibited a pronounced increase in the tendency to stand vertically and moved with qualitatively different characteristics than other cells. A decrease in the EPS secretion of cells correlates with a higher instantaneous velocity, but with lower directional persistence in trajectories. Moreover, EPS− cells do not adhere to the surface as strongly as wild-type and EPS overproducing cells, and display a greater tendency to have large deviations between the direction of movement and the cell axis, with cell velocity showing only minimal dependence on the direction of movement. The emerging picture is that EPS does not simply provide rheological resistance to a single mechanism but rather that the availability of EPS impacts motility pattern. PMID:26821939

A dual-mode disturbance-accommodating controller for the Hubble Space Telescope

NASA Astrophysics Data System (ADS)

Addington, Stewart; Johnson, C. D.

Cyclic thermal expansions and mechanical stiction effects in the Solar Arrays on the Hubble Space Telescope (HST) are triggering repeated occurrences of damped, relaxation-type flex-body vibrations of the solar arrays. Those solar array vibrations are, in turn, causing unwanted, oscillating disturbance torques on the HST main body, which cause unwanted deviations of the telescope from its specified pointing direction. In this paper we propose two strategies one can adopt in designing a telescope-pointing controller to cope with the aforementioned disturbances: (1) a `total isolation' (TI) control strategy whereby the HST controller torques are designed to adaptively counteract and cancel-out the persistent disturbing torques that are causing the unwanted telescope motions, and (2) an `array damping' (AD) control strategy whereby the HST controller torques are used to actively augment the natural dampening of the solar array vibrations and the attendant telescope motions, between triggerings of the stiction-related flex-body relaxation oscillations. Using the principles of Disturbance-Accommodating Control (DAC) Theory a dual-mode controller for a generic, planar-motion (single-axis) model of the HST is proposed. This controller incorporates both the TI and AD modes of disturbance-accommodation. Simulation studies of the closed-loop system using generic parameter values clearly indicate, qualitatively, the enhanced pointing-performance such a controller can achieve.

Effects of thermo-order-mechanical coupling on band structures in liquid crystal nematic elastomer porous phononic crystals.

PubMed

Yang, Shuai; Liu, Ying

2018-08-01

Liquid crystal nematic elastomers are one kind of smart anisotropic and viscoelastic solids simultaneously combing the properties of rubber and liquid crystals, which is thermal sensitivity. In this paper, the wave dispersion in a liquid crystal nematic elastomer porous phononic crystal subjected to an external thermal stimulus is theoretically investigated. Firstly, an energy function is proposed to determine thermo-induced deformation in NE periodic structures. Based on this function, thermo-induced band variation in liquid crystal nematic elastomer porous phononic crystals is investigated in detail. The results show that when liquid crystal elastomer changes from nematic state to isotropic state due to the variation of the temperature, the absolute band gaps at different bands are opened or closed. There exists a threshold temperature above which the absolute band gaps are opened or closed. Larger porosity benefits the opening of the absolute band gaps. The deviation of director from the structural symmetry axis is advantageous for the absolute band gap opening in nematic state whist constrains the absolute band gap opening in isotropic state. The combination effect of temperature and director orientation provides an added degree of freedom in the intelligent tuning of the absolute band gaps in phononic crystals. Copyright © 2018 Elsevier B.V. All rights reserved.

Accuracy of Patient Specific Cutting Blocks in Total Knee Arthroplasty

PubMed Central

Helmy, Naeder; Kühnel, Stefanie P.

2014-01-01

Background. Long-term survival of total knee arthroplasty (TKA) is mainly determined by optimal positioning of the components and prosthesis alignment. Implant positioning can be optimized by computer assisted surgery (CAS). Patient specific cutting blocks (PSCB) seem to have the potential to improve component alignment compared to the conventional technique and to be comparable to CAS. Methods. 113 knees were selected for PSI and included in this study. Pre- and postoperative mechanical axis, represented by the hip-knee-angle (HKA), the proximal tibial angle (PTA), the distal femoral angle (DFA), and the tibial slope (TS) were measured and the deviation from expected ideal values was calculated. Results. With a margin of error of ±3°, success rates were 81.4% for HKA, 92.0% for TPA, and 94.7% for DFA. With the margin of error for alignments extended to ±4°, we obtained a success rate of 92.9% for the HKA, 98.2% for the PTA, and 99.1% for the DFA. The TS showed postoperative results of 2.86 ± 2.02° (mean change 1.76 ± 2.85°). Conclusion. PSCBs for TKA seem to restore the overall leg alignment. Our data suggest that each individual component can be implanted accurately and the results are comparable to the ones in CAS. PMID:25254210

Adaptation of orientation vectors of otolith-related central vestibular neurons to gravity.

PubMed

Eron, Julia N; Cohen, Bernard; Raphan, Theodore; Yakushin, Sergei B

2008-09-01

Behavioral experiments indicate that central pathways that process otolith-ocular and perceptual information have adaptive capabilities. Because polarization vectors of otolith afferents are directly related to the electro-mechanical properties of the hair cell bundle, it is unlikely that they change their direction of excitation. This indicates that the adaptation must take place in central pathways. Here we demonstrate for the first time that otolith polarization vectors of canal-otolith convergent neurons in the vestibular nuclei have adaptive capability. A total of 10 vestibular-only and vestibular-plus-saccade neurons were recorded extracellularly in two monkeys before and after they were in side-down positions for 2 h. The spatial characteristics of the otolith input were determined from the response vector orientation (RVO), which is the projection of the otolith polarization vector, onto the head horizontal plane. The RVOs had no specific orientation before animals were in side-down positions but moved toward the gravitational axis after the animals were tilted for extended periods. Vector reorientations varied from 0 to 109 degrees and were linearly related to the original deviation of the RVOs from gravity in the position of adaptation. Such reorientation of central polarization vectors could provide the basis for changes in perception and eye movements related to prolonged head tilts relative to gravity or in microgravity.

Thoracic limb alignment in healthy labrador retrievers: evaluation of standing versus recumbent frontal plane radiography.

PubMed

Goodrich, Zachary J; Norby, Bo; Eichelberger, Bunita M; Friedeck, Wade O; Callis, Hollye N; Hulse, Don A; Kerwin, Sharon C; Fox, Derek B; Saunders, W Brian

2014-10-01

To report thoracic limb alignment values in healthy dogs; to determine if limb alignment values are significantly different when obtained from standing versus recumbent radiographic projections. Prospective cross-sectional study. Labrador Retrievers (n = 45) >15 months of age. Standing and recumbent radiographs were obtained and limb montages were randomized before analysis by a single investigator blinded to dog, limb, and limb position. Twelve limb alignment values were determined using the CORA methodology. Measurements were performed in triplicate and intra-observer variability was evaluated by intra-class correlation coefficient (ICC). Limb alignment values were reported as mean ± SD and 95% confidence intervals. Linear mixed models were used to determine if significant associations existed between limb alignment values and limb, limb position, gender, age, weight, and body condition score. There were significant differences in standing and recumbent limb alignment values for all values except elbow mechanical axis deviation (eMAD). Limb, gender, age, body weight, and body condition score had no effect. ICC values ranged from 0.522 to 0.758, indicating moderate to substantial agreement for repeated measurements by a single investigator. Limb alignment values are significantly different when determined from standing versus recumbent radiographs in healthy Labrador Retrievers. © Copyright 2014 by The American College of Veterinary Surgeons.

[Airway management in Ludwig's angina - a challenge: case report].

PubMed

Fellini, Roberto Taboada; Volquind, Daniel; Schnor, Otávio Haygert; Angeletti, Marcelo Gustavo; Souza, Olívia Egger de

Ludwig's angina (LA) is an infection of the submandibular space, first described by Wilhelm Frederick von Ludwig in 1836. It represents an entity difficult to manage due to the rapid progression and difficulty in maintaining airway patency, a major challenge in medical practice, resulting in asphyxia and death in 8-10% of patients. Describe a case of a patient with Ludwig's angina undergoing surgery, with emphasis on airway management, in addition to reviewing the articles published in the literature on this topic. Male patient, 21 years, drug addict, admitted by the emergency department and diagnosed with LA. Difficult airway was identified during the anesthetic examination. In additional tests, significant deviation from the tracheal axis was seen. Undergoing bilateral thoracoscopic pleural drainage, we opted for airway management through tracheal intubation using fiberoptic bronchoscopy, and balanced general anesthesia was proposed. There were no complications during the surgical-anesthetic act. After the procedure, the patient remained intubated and mechanically ventilated in the intensive care unit. Airway management in patients with Ludwig's angina remains challenging. The choice of the safest technique should be based on clinical signs, technical conditions available, and the urgent need to preserve the patient's life. Copyright © 2015 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

Visual error augmentation enhances learning in three dimensions.

PubMed

Sharp, Ian; Huang, Felix; Patton, James

2011-09-02

Because recent preliminary evidence points to the use of Error augmentation (EA) for motor learning enhancements, we visually enhanced deviations from a straight line path while subjects practiced a sensorimotor reversal task, similar to laparoscopic surgery. Our study asked 10 healthy subjects in two groups to perform targeted reaching in a simulated virtual reality environment, where the transformation of the hand position matrix was a complete reversal--rotated 180 degrees about an arbitrary axis (hence 2 of the 3 coordinates are reversed). Our data showed that after 500 practice trials, error-augmented-trained subjects reached the desired targets more quickly and with lower error (differences of 0.4 seconds and 0.5 cm Maximum Perpendicular Trajectory deviation) when compared to the control group. Furthermore, the manner in which subjects practiced was influenced by the error augmentation, resulting in more continuous motions for this group and smaller errors. Even with the extreme sensory discordance of a reversal, these data further support that distorted reality can promote more complete adaptation/learning when compared to regular training. Lastly, upon removing the flip all subjects quickly returned to baseline rapidly within 6 trials.

Evaluation of the navigation performance of shipboard-VTOL-landing guidance systems

NASA Technical Reports Server (NTRS)

Mcgee, L. A.; Paulk, C. H., Jr.; Steck, S. A.; Schmidt, S. F.; Merz, A. W.

1979-01-01

The objective of this study was to explore the performance of a VTOL aircraft landing approach navigation system that receives data (1) from either a microwave scanning beam (MSB) or a radar-transponder (R-T) landing guidance system, and (2) information data-linked from an aviation facility ship. State-of-the-art low-cost-aided inertial techniques and variable gain filters were used in the assumed navigation system. Compensation for ship motion was accomplished by a landing pad deviation vector concept that is a measure of the landing pad's deviation from its calm sea location. The results show that the landing guidance concepts were successful in meeting all of the current Navy navigation error specifications, provided that vector magnitude of the allowable error, rather than the error in each axis, is a permissible interpretation of acceptable performance. The success of these concepts, however, is strongly dependent on the distance measuring equipment bias. In addition, the 'best possible' closed-loop tracking performance achievable with the assumed point-mass VTOL aircraft guidance concept is demonstrated.

Extreme statistics and index distribution in the classical 1d Coulomb gas

NASA Astrophysics Data System (ADS)

Dhar, Abhishek; Kundu, Anupam; Majumdar, Satya N.; Sabhapandit, Sanjib; Schehr, Grégory

2018-07-01

We consider a 1D gas of N charged particles confined by an external harmonic potential and interacting via the 1D Coulomb potential. For this system we show that in equilibrium the charges settle, on an average, uniformly and symmetrically on a finite region centred around the origin. We study the statistics of the position of the rightmost particle and show that the limiting distribution describing its typical fluctuations is different from the Tracy–Widom distribution found in the 1D log-gas. We also compute the large deviation functions which characterise the atypical fluctuations of far away from its mean value. In addition, we study the gap between the two rightmost particles as well as the index N + , i.e. the number of particles on the positive semi-axis. We compute the limiting distributions associated to the typical fluctuations of these observables as well as the corresponding large deviation functions. We provide numerical supports to our analytical predictions. Part of these results were announced in a recent letter, Dhar et al (2017 Phys. Rev. Lett. 119 060601).

Implementation of small field radiotherapy dosimetry for spinal metastase case

NASA Astrophysics Data System (ADS)

Rofikoh, Wibowo, W. E.; Pawiro, S. A.

2017-07-01

The main objective of this study was to know dose profile of small field radiotherapy in the spinal metastase case with source axis distance (SAD) techniques. In addition, we evaluated and compared the dose planning of stereotactic body radiation therapy (SBRT) and conventional techniques to measurements with Exradin A16 and Gafchromic EBT3 film dosimeters. The results showed that film EBT3 had a highest precision and accuracy with the average of the standard deviation of ±1.7 and maximum discrepancy of 2.6 %. In addition, the average value of Full Wave Half Maximum (FWHM) and its largest deviation in small field size of 0.8 x 0.8 cm2 are 0.82 cm and 16.3 % respectively, while it was found around 2.36 cm and 3 % for the field size of 2.4 x 2.4 cm2. The comparison between penumbra width and the collimation was around of 37.1 % for the field size of 0.8 x 0.8 cm2, while it was found of 12.4 % for the field size of 2.4 x 2.4 cm2.

78 FR 45863 - Drawbridge Operation Regulation; Atlantic Intracoastal Waterway (AICW), Elizabeth River, Southern...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-30

... operation of the Belt Line Railroad Bridge, across the Elizabeth River Southern Branch, AICW, mile 2.6, at Chesapeake and Portsmouth, VA. This deviation is necessary to facilitate mechanical and electrical upgrades on the Belt Line Railroad drawbridge. This temporary deviation allows the drawbridge to remain in the...

A high bandwidth three-axis out-of-plane motion measurement system based on optical beam deflection

NASA Astrophysics Data System (ADS)

Piyush, P.; Giridhar, M. S.; Jayanth, G. R.

2018-03-01

Multi-axis measurement of motion is indispensable for characterization of dynamic systems and control of motion stages. This paper presents an optical beam deflection-based measurement system to simultaneously measure three-axis out-of-plane motion of both micro- and macro-scale targets. Novel strategies are proposed to calibrate the sensitivities of the measurement system. Subsequently the measurement system is experimentally realized and calibrated. The system is employed to characterize coupled linear and angular motion of a piezo-actuated stage. The measured motion is shown to be in agreement with theoretical expectation. Next, the high bandwidth of the measurement system has been showcased by utilizing it to measure coupled two-axis transient motion of a Radio Frequency Micro-Electro-Mechanical System switch with a rise time of about 60 μs. Finally, the ability of the system to measure out-of-plane angular motion about the second axis has been demonstrated by measuring the deformation of a micro-cantilever beam.

The high-efficiency laundry metering and marketing analysis (THELMA) project: Volume 2 -- Laboratory testing of clothes washers. Final report

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

NONE

1997-10-01

Horizontal axis (H-axis) clothes washers use less water and energy than conventional top-loading vertical axis (V-axis) clothes washers, yet sales in the US are insignificant. In the High Efficiency Laundry Metering and Market Analysis (THELMA) project, EPRI and a group of utilities have pooled their resources to develop the basis for successful DSM programs to accelerate the acceptance of this technology in the US market. This report covers the laboratory test phase of the THELMA project. The objective of this effort was to measure the performance of a representative sample of currently manufactured H-axis washers and to compare this performancemore » to that of a typical V-axis washer. Several aspects of performance were measured, with the emphasis on measures of energy consumption and water consumption: DOE washer capacity; hot and cold water consumption; energy consumption by the washer mechanical drive; DOE energy factor; water extraction effectiveness; effect of water extraction effectiveness on dryer energy; soil removal effectiveness; rinsing effectiveness; and gentleness of action. Eight H-axis washers, provided by US or European manufacturers, were tested. Test results varied over a range for these eight machines, but on average, the H-axis washers used 40% less energy (normalized to basket volume) and 25% less water (normalized to basket volume) when measured according to the DOE test procedure.« less

Laboratory testing of clothes washers. Final report

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

Dieckmann, J.; Murphy, W.

1995-12-01

Horizontal axis (H-axis) clothes washers use less water and energy than conventional top-loading vertical axis (V-axis) clothes washers, yet sales in the US are insignificant. In the High Efficiency Laundry Metering and Market Analysis (THELMA) project, EPRI and a group of utilities have pooled their resources to develop the basis for successful DSM programs to accelerate the acceptance of this technology in the US market. This report covers the laboratory test phase of the THELMA project. The objective of this effort was to measure the performance of a representative sample of currently manufactured H-axis washers and to compare this performancemore » to that of a typical V-axis washer. Several aspects of performance were measured, with the emphasis on measures of energy consumption and water consumption: DOE washer capacity; Hot and cold water consumption; Energy consumption by the washer mechanical drive; DOE energy factor; Water extraction effectiveness; Effect of water extraction effectiveness on dryer energy; Soil removal effectiveness; Rinsing effectiveness and Gentleness of action. Six H-axis washers, provided by US or European manufacturers, were tested. Test results varied over a range for these six machines, but on average, the H-axis washers used 40% less energy (normalized to basket volume) and 25% less water (normalized to basket volume) when measured according to the DOE test procedure.« less

Modeling and design of a two-axis elliptical notch flexure hinge

NASA Astrophysics Data System (ADS)

Wu, Jianwei; Zhang, Yin; Lu, Yunfeng; Wen, Zhongpu; Bin, Deer; Tan, Jiubin

2018-04-01

As an important part of the joule balance system, the two-axis elliptical notch flexure hinge (TENFH) which typically consists of two single-axis elliptical notch flexure hinges was studied. First, a 6 degrees of freedom (6-DOF) compliance model was established based on the coordinate transformation method. In addition, the maximum stress of the TENFH was derived. The compliance and maximum stress model was verified using finite element analysis simulation. To decouple the attitude of the suspended coil system and reduce the offset between the centroid of the suspended coil mechanism and the mass comparator in the joule balance system, a new mechanical structure of TENFH was designed based on the compliance model and stress model proposed in this paper. The maximum rotation range is up to 10°, and the axial load is more than 5 kg, which meets the requirements of the system. The compliance model was also verified by deformation experimentation with the designed TENFH.

A cytokine axis regulates elastin formation and degradation

PubMed Central

Sproul, Erin P.; Argraves, W. Scott

2013-01-01

Underlying the dynamic regulation of tropoelastin expression and elastin formation in development and disease are transcriptional and post-transcriptional mechanisms that have been the focus of much research. Of particular importance is the cytokine–governed elastin regulatory axis in which the pro-elastogenic activities of transforming growth factor β-1 (TGFβ1) and insulin-like growth factor-I (IGF-I) are opposed by anti-elastogenic activities of basic fibroblast growth factor (bFGF/FGF-2), heparin-binding epidermal growth factor-like growth factor (HB-EGF), EGF, PDGF-BB, TGFα, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β and noncanonical TGFβ1 signaling. A key mechanistic feature of the regulatory axis is that cytokines influence elastin formation through effects on the cell cycle involving control of cyclin–cyclin dependent kinase complexes and activation of the Ras/MEK/ERK signaling pathway. In this article we provide an overview of the major cytokines/growth factors that modulate elastogenesis and describe the underlying molecular mechanisms for their action on elastin production. PMID:23160093

Uncontrolled angiogenic precursor expansion causes coronary artery anomalies in mice lacking Pofut1.

PubMed

Wang, Yidong; Wu, Bingruo; Lu, Pengfei; Zhang, Donghong; Wu, Brian; Varshney, Shweta; Del Monte-Nieto, Gonzalo; Zhuang, Zhenwu; Charafeddine, Rabab; Kramer, Adam H; Sibinga, Nicolas E; Frangogiannis, Nikolaos G; Kitsis, Richard N; Adams, Ralf H; Alitalo, Kari; Sharp, David J; Harvey, Richard P; Stanley, Pamela; Zhou, Bin

2017-09-18

Coronary artery anomalies may cause life-threatening cardiac complications; however, developmental mechanisms underpinning coronary artery formation remain ill-defined. Here we identify an angiogenic cell population for coronary artery formation in mice. Regulated by a DLL4/NOTCH1/VEGFA/VEGFR2 signaling axis, these angiogenic cells generate mature coronary arteries. The NOTCH modulator POFUT1 critically regulates this signaling axis. POFUT1 inactivation disrupts signaling events and results in excessive angiogenic cell proliferation and plexus formation, leading to anomalous coronary arteries, myocardial infarction and heart failure. Simultaneous VEGFR2 inactivation fully rescues these defects. These findings show that dysregulated angiogenic precursors link coronary anomalies to ischemic heart disease.Though coronary arteries are crucial for heart function, the mechanisms guiding their formation are largely unknown. Here, Wang et al. identify a unique, endocardially-derived angiogenic precursor cell population for coronary artery formation in mice and show that a DLL4/NOTCH1/VEGFA/VEGFR2 signaling axis is key for coronary artery development.

Anxiety and the aging brain: stressed out over p53?

PubMed

Scrable, Heidi; Burns-Cusato, Melissa; Medrano, Silvia

2009-12-01

We propose a model in which cell loss in the aging brain is seen as a root cause of behavioral changes that compromise quality of life, including the onset of generalized anxiety disorder, in elderly individuals. According to this model, as stem cells in neurogenic regions of the adult brain lose regenerative capacity, worn-out, dead, or damaged neurons fail to be replaced, leaving gaps in function. As most replacement involves inhibitory interneurons, either directly or indirectly, the net result is the acquisition over time of a hyper-excitable state. The stress axis is subserved by all three neurogenic regions in the adult brain, making it particularly susceptible to these age-dependent changes. We outline a molecular mechanism by which hyper-excitation of the stress axis in turn activates the tumor suppressor p53. This reinforces the loss of stem cell proliferative capacity and interferes with the feedback mechanism by which the glucocorticoid receptor turns off neuroendocrine pathways and resets the axis.

Teaching Quantum Mechanics on an Introductory Level.

ERIC Educational Resources Information Center

Muller, Rainer; Wiesner, Hartmut

2002-01-01

Presents a new research-based course on quantum mechanics in which the conceptual issues of quantum mechanics are taught at an introductory level. Involves students in the discovery of how quantum phenomena deviate from classical everyday experiences. (Contains 31 references.) (Author/YDS)

Resonant obliquity of Mars?. [climate driven by spin axis and orbit plane precession caused oscillations

NASA Technical Reports Server (NTRS)

Ward, William R.; Rudy, Donald J.

1991-01-01

The large-scale oscillations generated by the obliquity of Mars through spin-axis and orbit-plane precessions constitute basic climate system drivers with periodicities of 100,000 yrs in differential spin axis-orbit precession rates and of over 1 million yrs in amplitude modulations due to orbital-inclination changes. Attention is presently given to a third time-scale for climate change, which involves a possible spin-spin resonance and whose mechanism operates on a 10-million-yr time-scale: this effect implies an average obliquity increase for Mars of 15 deg only 5 million yrs ago, with important climatic consequences.

Motor equivalence during multi-finger accurate force production

PubMed Central

Mattos, Daniela; Schöner, Gregor; Zatsiorsky, Vladimir M.; Latash, Mark L.

2014-01-01

We explored stability of multi-finger cyclical accurate force production action by analysis of responses to small perturbations applied to one of the fingers and inter-cycle analysis of variance. Healthy subjects performed two versions of the cyclical task, with and without an explicit target. The “inverse piano” apparatus was used to lift/lower a finger by 1 cm over 0.5 s; the subjects were always instructed to perform the task as accurate as they could at all times. Deviations in the spaces of finger forces and modes (hypothetical commands to individual fingers) were quantified in directions that did not change total force (motor equivalent) and in directions that changed the total force (non-motor equivalent). Motor equivalent deviations started immediately with the perturbation and increased progressively with time. After a sequence of lifting-lowering perturbations leading to the initial conditions, motor equivalent deviations were dominating. These phenomena were less pronounced for analysis performed with respect to the total moment of force with respect to an axis parallel to the forearm/hand. Analysis of inter-cycle variance showed consistently higher variance in a subspace that did not change the total force as compared to the variance that affected total force. We interpret the results as reflections of task-specific stability of the redundant multi-finger system. Large motor equivalent deviations suggest that reactions of the neuromotor system to a perturbation involve large changes of neural commands that do not affect salient performance variables, even during actions with the purpose to correct those salient variables. Consistency of the analyses of motor equivalence and variance analysis provides additional support for the idea of task-specific stability ensured at a neural level. PMID:25344311

Prosthetically guided maxillofacial surgery: evaluation of the accuracy of a surgical guide and custom-made bone plate in oncology patients after mandibular reconstruction.

PubMed

Mazzoni, Simona; Marchetti, Claudio; Sgarzani, Rossella; Cipriani, Riccardo; Scotti, Roberto; Ciocca, Leonardo

2013-06-01

The aim of the present study was to evaluate the accuracy of prosthetically guided maxillofacial surgery in reconstructing the mandible with a free vascularized flap using custom-made bone plates and a surgical guide to cut the mandible and fibula. The surgical protocol was applied in a study group of seven consecutive mandibular-reconstructed patients who were compared with a control group treated using the standard preplating technique on stereolithographic models (indirect computer-aided design/computer-aided manufacturing method). The precision of both surgical techniques (prosthetically guided maxillofacial surgery and indirect computer-aided design/computer-aided manufacturing procedure) was evaluated by comparing preoperative and postoperative computed tomographic data and assessment of specific landmarks. With regard to midline deviation, no significant difference was documented between the test and control groups. With regard to mandibular angle shift, only one left angle shift on the lateral plane showed a statistically significant difference between the groups. With regard to angular deviation of the body axis, the data showed a significant difference in the arch deviation. All patients in the control group registered greater than 8 degrees of deviation, determining a facial contracture of the external profile at the lower margin of the mandible. With regard to condylar position, the postoperative condylar position was better in the test group than in the control group, although no significant difference was detected. The new protocol for mandibular reconstruction using computer-aided design/computer-aided manufacturing prosthetically guided maxillofacial surgery to construct custom-made guides and plates may represent a viable method of reproducing the patient's anatomical contour, giving the surgeon better procedural control and reducing procedure time. Therapeutic, III.

Mechanical Validation of an MRI Compatible Stereotactic Neurosurgery Robot in Preparation for Pre-Clinical Trials.

PubMed

Nycz, Christopher J; Gondokaryono, Radian; Carvalho, Paulo; Patel, Nirav; Wartenberg, Marek; Pilitsis, Julie G; Fischer, Gregory S

2017-09-01

The use of magnetic resonance imaging (MRI) for guiding robotic surgical devices has shown great potential for performing precisely targeted and controlled interventions. To fully realize these benefits, devices must work safely within the tight confines of the MRI bore without negatively impacting image quality. Here we expand on previous work exploring MRI guided robots for neural interventions by presenting the mechanical design and assessment of a device for positioning, orienting, and inserting an interstitial ultrasound-based ablation probe. From our previous work we have added a 2 degree of freedom (DOF) needle driver for use with the aforementioned probe, revised the mechanical design to improve strength and function, and performed an evaluation of the mechanism's accuracy and effect on MR image quality. The result of this work is a 7-DOF MRI robot capable of positioning a needle tip and orienting it's axis with accuracy of 1.37 ± 0.06 mm and 0.79° ± 0.41°, inserting it along it's axis with an accuracy of 0.06 ± 0.07 mm , and rotating it about it's axis to an accuracy of 0.77° ± 1.31°. This was accomplished with no significant reduction in SNR caused by the robot's presence in the MRI bore, ≤ 10.3% reduction in SNR from running the robot's motors during a scan, and no visible paramagnetic artifacts.

SU-F-T-547: Off-Isocenter Winston-Lutz Test for Stereotactic Radiosurgery/stereotactic Body Radiotherapy

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

Gao, J; Liu, X

2016-06-15

Purpose: To perform a quantitative study to verify that the mechanical field center coincides with the radiation field center when both are off from the isocenter during the single-isocenter technique in linear accelerator-based SRS/SBRT procedure to treat multiple lesions. Methods: We developed an innovative method to measure this accuracy, called the off-isocenter Winston-Lutz test, and here we provide a practical clinical guideline to implement this technique. We used ImagePro V.6 to analyze images of a Winston-Lutz phantom obtained using a Varian 21EX linear accelerator with an electronic portal imaging device, set up as for single-isocenter SRS/SBRT for multiple lesions. Wemore » investigated asymmetry field centers that were 3 cm and 5 cm away from the isocenter, as well as performing the standard Winston-Lutz test. We used a special beam configuration to acquire images while avoiding collision, and we investigated both jaw and multileaf collimation. Results: For the jaw collimator setting, at 3 cm off-isocenter, the mechanical field deviated from the radiation field by about 2.5 mm; at 5 cm, the deviation was above 3 mm, up to 4.27 mm. For the multileaf collimator setting, at 3 cm off-isocenter, the deviation was below 1 mm; at 5 cm, the deviation was above 1 mm, up to 1.72 mm, which is 72% higher than the tolerance threshold. Conclusion: These results indicated that the further the asymmetry field center is from the machine isocenter, the larger the deviation of the mechanical field from the radiation field, and the distance between the center of the asymmetry field and the isocenter should not exceed 3 cm in of our clinic. We recommend that every clinic that uses linear accelerator, multileaf collimator-based SRS/SBRT perform the off-isocenter Winston-Lutz test in addition to the standard Winston-Lutz test and use their own deviation data to design the treatment plan.« less

The A/P axis in echinoderm ontogeny and evolution: evidence from fossils and molecules

NASA Technical Reports Server (NTRS)

Peterson, K. J.; Arenas-Mena, C.; Davidson, E. H.

2000-01-01

Even though echinoderms are members of the Bilateria, the location of their anterior/posterior axis has remained enigmatic. Here we propose a novel solution to the problem employing three lines of evidence: the expression of a posterior class Hox gene in the coeloms of the nascent adult body plan within the larva; the anatomy of certain early fossil echinoderms; and finally the relation between endoskeletal plate morphology and the associated coelomic tissues. All three lines of evidence converge on the same answer, namely that the location of the adult mouth is anterior, and the anterior/posterior axis runs from the mouth through the adult coelomic compartments. This axis then orients the animal such that there is but a single plane of symmetry dividing the animal into left and right halves. We tentatively hypothesize that this plane of symmetry is positioned along the dorsal/ventral axis. These axis identifications lead to the conclusion that the five ambulacra are not primary body axes, but instead are outgrowths from the central anterior/posterior axis. These identifications also shed insight into several other evolutionary mysteries of various echinoderm clades such as the independent evolution of bilateral symmetry in irregular echinoids, but do not elucidate the underlying mechanisms of the adult coelomic architecture.

Pick-and-place process for sensitivity improvement of the capacitive type CMOS MEMS 2-axis tilt sensor

NASA Astrophysics Data System (ADS)

Chang, Chun-I.; Tsai, Ming-Han; Liu, Yu-Chia; Sun, Chih-Ming; Fang, Weileun

2013-09-01

This study exploits the foundry available complimentary metal-oxide-semiconductor (CMOS) process and the packaging house available pick-and-place technology to implement a capacitive type micromachined 2-axis tilt sensor. The suspended micro mechanical structures such as the spring, stage and sensing electrodes are fabricated using the CMOS microelectromechanical systems (MEMS) processes. A bulk block is assembled onto the suspended stage by pick-and-place technology to increase the proof-mass of the tilt sensor. The low temperature UV-glue dispensing and curing processes are employed to bond the block onto the stage. Thus, the sensitivity of the CMOS MEMS capacitive type 2-axis tilt sensor is significantly improved. In application, this study successfully demonstrates the bonding of a bulk solder ball of 100 µm in diameter with a 2-axis tilt sensor fabricated using the standard TSMC 0.35 µm 2P4M CMOS process. Measurements show the sensitivities of the 2-axis tilt sensor are increased for 2.06-fold (x-axis) and 1.78-fold (y-axis) after adding the solder ball. Note that the sensitivity can be further improved by reducing the parasitic capacitance and the mismatch of sensing electrodes caused by the solder ball.

Modulation of Gut Microbiota-Brain Axis by Probiotics, Prebiotics, and Diet.

PubMed

Liu, Xiaofei; Cao, Shangqing; Zhang, Xuewu

2015-09-16

There exists a bidirectional communication system between the gastrointestinal tract and the brain. Increasing evidence shows that gut microbiota can play a critical role in this communication; thus, the concept of a gut microbiota and brain axis is emerging. Here, we review recent findings in the relationship between intestinal microbes and brain function, such as anxiety, depression, stress, autism, learning, and memory. We highlight the advances in modulating brain development and behavior by probiotics, prebiotics, and diet through the gut microbiota-brain axis. A variety of mechanisms including immune, neural, and metabolic pathways may be involved in modulation of the gut microbiota-brain axis. We also discuss some future challenges. A deeper understanding of the relationship between the gut bacteria and their hosts is implicated in developing microbial-based therapeutic strategies for brain disorders.

Analysis of Statoliths Displacement in Chara Rhizoids for Validating the Microgravity-Simulation Quality of Clinorotation Modes

NASA Astrophysics Data System (ADS)

Krause, Lars; Braun, Markus; Hauslage, Jens; Hemmersbach, Ruth

2018-05-01

In single-celled rhizoids of the green algae Chara, positively gravitropic growth is governed by statoliths kept in a dynamically stable position 10-25 μ m above the cell tip by a complex interaction of gravity and actomyosin forces. Any deviation of the tube-like cells from the tip-downward orientation causes statoliths to sediment onto the gravisensitive subapical cell flank which initiates a gravitropic curvature response. Microgravity experiments have shown that abolishing the net tip-directed gravity force results in an actomyosin-mediated axial displacement of statoliths away from the cell tip. The present study was performed to critically assess the quality of microgravity simulation provided by different operational modes of a Random Positioning Machine (RPM) running with one axis (2D mode) or two axes (3D mode) and different rotational speeds (2D), speed ranges and directions (3D). The effects of 2D and 3D rotation were compared with data from experiments in real microgravity conditions (MAXUS sounding rocket missions). Rotational speeds in the range of 60-85 rpm in 2D and 3D modes resulted in a similar kinetics of statolith displacement as compared to real microgravity data, while slower clinorotation (2-11 rpm) caused a reduced axial displacement and a more dispersed arrangement of statoliths closer to the cell tip. Increasing the complexity of rotation by adding a second rotation axis in case of 3D clinorotation did not increase the quality of microgravity simulation, however, increased side effects such as the level of vibrations resulting in a more dispersed arrangement of statoliths. In conclusion, fast 2D clinorotation provides the most appropriate microgravity simulation for investigating the graviperception mechanism in Chara rhizoids, whereas slower clinorotation speeds and rotating samples around two axes do not improve the quality of microgravity simulation.

Comparison between Different Methods for Biomechanical Assessment of Ex Vivo Fracture Callus Stiffness in Small Animal Bone Healing Studies

PubMed Central

Steiner, Malte; Volkheimer, David; Meyers, Nicholaus; Wehner, Tim; Wilke, Hans-Joachim; Claes, Lutz; Ignatius, Anita

2015-01-01

For ex vivo measurements of fracture callus stiffness in small animals, different test methods, such as torsion or bending tests, are established. Each method provides advantages and disadvantages, and it is still debated which of those is most sensitive to experimental conditions (i.e. specimen alignment, directional dependency, asymmetric behavior). The aim of this study was to experimentally compare six different testing methods regarding their robustness against experimental errors. Therefore, standardized specimens were created by selective laser sintering (SLS), mimicking size, directional behavior, and embedding variations of respective rat long bone specimens. For the latter, five different geometries were created which show shifted or tilted specimen alignments. The mechanical tests included three-point bending, four-point bending, cantilever bending, axial compression, constrained torsion, and unconstrained torsion. All three different bending tests showed the same principal behavior. They were highly dependent on the rotational direction of the maximum fracture callus expansion relative to the loading direction (creating experimental errors of more than 60%), however small angular deviations (<15°) were negligible. Differences in the experimental results between the bending tests originate in their respective location of maximal bending moment induction. Compared to four-point bending, three-point bending is easier to apply on small rat and mouse bones under realistic testing conditions and yields robust measurements, provided low variation of the callus shape among the tested specimens. Axial compressive testing was highly sensitive to embedding variations, and therefore cannot be recommended. Although it is experimentally difficult to realize, unconstrained torsion testing was found to be the most robust method, since it was independent of both rotational alignment and embedding uncertainties. Constrained torsional testing showed small errors (up to 16.8%, compared to corresponding alignment under unconstrained torsion) due to a parallel offset between the specimens’ axis of gravity and the torsional axis of rotation. PMID:25781027

The experimental basis for interpreting particle and magnetic fabrics of sheared till

USGS Publications Warehouse

Iverson, N.R.; Hooyer, T.S.; Thomason, J.F.; Graesch, M.; Shumway, J.R.

2008-01-01

Particle fabrics of basal tills may allow testing of the bed-deformation model of glacier flow, which requires high bed shear strains (>100). Field studies, however, have not yielded a systematic relationship between shear-strain magnitude and fabric development. To isolate this relationship four basal tills and viscous putty were sheared in a ring-shear device to strains as high as 714. Fabric was characterized within a zone of shear deformation using the long-axis orientations of fine-gravel and sand particles and the anisotropy of magnetic susceptibility (AMS) of small (???5-8 cm3) intact samples. Results indicate that till particles rotate toward the plane of shearing with long-axis orientations that become tightly clustered in the direction of shear (0??78 < S1 < 0??94 for three-dimensional data). These strong, steady-state fabrics are attained at shear strains of 7-30, with no evidence of fabric weakening with further strain, regardless of the specific till or particle-size fraction under consideration. These results do not support the Jeffery model of particle rotation, which correctly describes particle rotation in the viscous putty but not in the tills, owing to fluid-mechanical assumptions of the model that are violated in till. The sensitivity of fabric development to shear-strain magnitude indicates that, for most till units where shear-strain magnitude is poorly known, attributing fabric variations to spatial differences in other variables, such as till thickness or water content, will be inherently speculative. Attributing fabric characteristics to particular basal till facies is uncertain because shear-strain magnitude is unlikely to be closely correlated to till facies. Weak or spatially variable fabrics, in the absence of post-depositional disturbance or major deviations from unidirectional simple shear, indicate that till has not been pervasively sheared to the high strains required by the bed-deformation model. Strong flow-parallel fabrics are a necessary but insufficient criterion for confirming the model. Copyright ?? 2008 John Wiley & Sons, Ltd.

Analysis of Statoliths Displacement in Chara Rhizoids for Validating the Microgravity-Simulation Quality of Clinorotation Modes

NASA Astrophysics Data System (ADS)

Krause, Lars; Braun, Markus; Hauslage, Jens; Hemmersbach, Ruth

2018-01-01

In single-celled rhizoids of the green algae Chara, positively gravitropic growth is governed by statoliths kept in a dynamically stable position 10-25 μ m above the cell tip by a complex interaction of gravity and actomyosin forces. Any deviation of the tube-like cells from the tip-downward orientation causes statoliths to sediment onto the gravisensitive subapical cell flank which initiates a gravitropic curvature response. Microgravity experiments have shown that abolishing the net tip-directed gravity force results in an actomyosin-mediated axial displacement of statoliths away from the cell tip. The present study was performed to critically assess the quality of microgravity simulation provided by different operational modes of a Random Positioning Machine (RPM) running with one axis (2D mode) or two axes (3D mode) and different rotational speeds (2D), speed ranges and directions (3D). The effects of 2D and 3D rotation were compared with data from experiments in real microgravity conditions (MAXUS sounding rocket missions). Rotational speeds in the range of 60-85 rpm in 2D and 3D modes resulted in a similar kinetics of statolith displacement as compared to real microgravity data, while slower clinorotation (2-11 rpm) caused a reduced axial displacement and a more dispersed arrangement of statoliths closer to the cell tip. Increasing the complexity of rotation by adding a second rotation axis in case of 3D clinorotation did not increase the quality of microgravity simulation, however, increased side effects such as the level of vibrations resulting in a more dispersed arrangement of statoliths. In conclusion, fast 2D clinorotation provides the most appropriate microgravity simulation for investigating the graviperception mechanism in Chara rhizoids, whereas slower clinorotation speeds and rotating samples around two axes do not improve the quality of microgravity simulation.

The Role of the Pituitary-Adrenocortical Axis System in the Regulation of Secretion of Digestive Glands of Wrestlers during Sports and Postsports Ontogenesis

ERIC Educational Resources Information Center

Panov, Sergei F.; Panova, Irina P.; Volunskaya, Elena V.; Chebotarev, Andrei V.

2016-01-01

According to many researchers its necessary to research a hormonal profile in order to determine mechanisms of regulation of functions of the digestive conveyor during sports activities. In the paper the results of the carried out research on studying of a role of pituitary-adrenocortical axis system of adaptive reactions in activities of the…

Low-Friction, Low-Profile, High-Moment Two-Axis Joint

NASA Technical Reports Server (NTRS)

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

2010-01-01

The two-axis joint is a mechanical device that provides two-degrees-of-freedom motion between connected components. A compact, moment-resistant, two-axis joint is used to connect an electromechanical actuator to its driven structural members. Due to the requirements of the overall mechanism, the joint has a low profile to fit within the allowable space, low friction, and high moment-reacting capability. The mechanical arrangement of this joint can withstand high moments when loads are applied. These features allow the joint to be used in tight spaces where a high load capability is required, as well as in applications where penetrating the mounting surface is not an option or where surface mounting is required. The joint consists of one base, one clevis, one cap, two needle bearings, and a circular shim. The base of the joint is the housing (the base and the cap together), and is connected to the grounding structure via fasteners and a bolt pattern. Captive within the housing, between the base and the cap, are the rotating clevis and the needle bearings. The clevis is attached to the mechanical system (linear actuator) via a pin. This pin, and the rotational movement of the clevis with respect to the housing, provides two rotational degrees of freedom. The larger diameter flange of the clevis is sandwiched between a pair of needle bearings, one on each side of the flange. During the assembly of the two-axis joint, the circular shims are used to adjust the amount of preload that is applied to the needle bearings. The above arrangement enables the joint to handle high moments with minimal friction. To achieve the high-moment capability within a low-profile joint, the use of depth of engagement (like that of a conventional rotating shaft) to react moment is replaced with planar engagement parallel to the mounting surface. The needle bearings with the clevis flange provide the surface area to react the clevis loads/moments into the joint housing while providing minimal friction during rotation. The diameter of the flange and the bearings can be increased to react higher loads and still maintain a compact surface mounting capability. This type of joint can be used in a wide variety of mechanisms and mechanical systems. It is especially effective where precise, smooth, continuous motion is required. For example, the joint can be used at the end of a linear actuator that is required to extend and rotate simultaneously. The current design application is for use in a spacecraft docking-system capture mechanism. Other applications might include industrial robotic or assembly line apparatuses, positioning systems, or in the motion-based simulator industry that employs complex, multi-axis manipulators for various types of motions.

Hotspot-Ridge Interaction: Shaping the Geometry of Mid-Ocean Ridges

NASA Astrophysics Data System (ADS)

Mittelstaedt, E.; Ito, G.

2004-12-01

Surface manifestations of hotspot-ridge interaction include geochemical anomalies, elevated ridge topography, negative gravity anomalies, off-axis volcanic lineaments, and ridge reorganization events. The last of these is expressed as either "captured" ridge segments due to asymmetric spreading, such as at the Galapagos, or as discrete jumps of the ridge axis toward the hotspot, such as at the Iceland, Tristan de Cuhna, Discovery, Shona, Louisville, Kerguelen, and Reunion hotspots. Mid-ocean ridge axis reorganizations through discrete jumps will cause variations in local volcanic patterns, lead to changes in overall plate shape and ridge axis morphology, and alter local mantle flow patterns. It has been proposed that discrete ridge jumps are a product of interaction between the lithosphere and a mantle plume. We examine this hypothesis using thin plate theory coupled with continuum damage mechanics to calculate the two-dimensional (plan-view) pattern of depth-integrated stresses in a plate of varying thickness with weakening due to volcanism at the ridge and above the plume center. Forces on the plate include plume shear, plate parallel gravitational forces due to buoyant uplift, and a prescribed velocity of plate motion along the edges of the model. We explore these forces and the effect of damage as mechanisms that may be required to predict ridge jumps.

The influence of mechanical gear on the efficiency of small hydropower

NASA Astrophysics Data System (ADS)

Ferenc, Zbigniew; Sambor, Aleksandra

2017-11-01

Pursuant to the "Strategy of development of renewable energy", an increase in the share of renewable energy sources in the national fuel-energy balance up to 14% by 2020 is planned in the structure of usage of primary energy carriers. The change in the participation of the clean energy in the energy balance may be done not only by the erection of new and renovation of the already existing plants, but also through an improvement of their energetic efficiency. The study presents the influence of the mechanical gear used on the quantity of energy produced by a small hydropower on the basis of SHP Rzepcze in Opole province in 2005-2010. The primary kinematic system was composed of a Francis turbine of a vertical axis, a toothed intersecting axis gear of 1:1 ratio, a belt gear of a double ratio. After a modernization the system was simplified by means of reducing the intersecting axis gear and the double ratio of the belt gear. The new kinematic system utilized a single-ratio belt gear of a vertical axis. After the kinematic system was rearranged, a significant improvement of efficiency of the small hydropower was concluded, which translates into an increase of the amount of energy produced.

Synthesis and Evaluation of A High Precision 3D-Printed Ti6Al4V Compliant Parallel Manipulator

NASA Astrophysics Data System (ADS)

Pham, Minh Tuan; Teo, Tat Joo; Huat Yeo, Song; Wang, Pan; Nai, Mui Ling Sharon

2017-12-01

A novel 3D printed compliant parallel manipulator (CPM) with θX - θX - Z motions is presented in this paper. This CPM is synthesized using the beam-based method, a new structural optimization approach, to achieve optimized stiffness properties with targeted dynamic behavior. The CPM performs high non-actuating stiffness based on the predicted stiffness ratios of about 3600 for translations and 570 for rotations, while the dynamic response is fast with the targeted first resonant mode of 100Hz. A prototype of the synthesized CPM is fabricated using the electron beam melting (EBM) technology with Ti6Al4V material. Driven by three voice-coil (VC) motors, the CPM demonstrated a positioning resolution of 50nm along the Z axis and an angular resolution of ~0.3 “about the X and Y axes, the positioning accuracy is also good with the measured values of ±25.2nm and ±0.17” for the translation and rotations respectively. Experimental investigation also shows that this large workspace CPM has a first resonant mode of 98Hz and the stiffness behavior matches the prediction with the highest deviation of 11.2%. Most importantly, the full workspace of 10° × 10° × 7mm of the proposed CPM can be achieved, that demonstrates 3D printed compliant mechanisms can perform large elastic deformation. The obtained results show that CPMs printed by EBM technology have predictable mechanical characteristics and are applicable in precise positioning systems.

Determination of Small Animal Long Bone Properties Using Densitometry

NASA Technical Reports Server (NTRS)

Breit, Gregory A.; Goldberg, BethAnn K.; Whalen, Robert T.; Hargens, Alan R. (Technical Monitor)

1996-01-01

Assessment of bone structural property changes due to loading regimens or pharmacological treatment typically requires destructive mechanical testing and sectioning. Our group has accurately and non-destructively estimated three dimensional cross-sectional areal properties (principal moments of inertia, Imax and Imin, and principal angle, Theta) of human cadaver long bones from pixel-by-pixel analysis of three non-coplanar densitometry scans. Because the scanner beam width is on the order of typical small animal diapbyseal diameters, applying this technique to high-resolution scans of rat long bones necessitates additional processing to minimize errors induced by beam smearing, such as dependence on sample orientation and overestimation of Imax and Imin. We hypothesized that these errors are correctable by digital image processing of the raw scan data. In all cases, four scans, using only the low energy data (Hologic QDR-1000W, small animal mode), are averaged to increase image signal-to-noise ratio. Raw scans are additionally processed by interpolation, deconvolution by a filter derived from scanner beam characteristics, and masking using a variable threshold based on image dynamic range. To assess accuracy, we scanned an aluminum step phantom at 12 orientations over a range of 180 deg about the longitudinal axis, in 15 deg increments. The phantom dimensions (2.5, 3.1, 3.8 mm x 4.4 mm; Imin/Imax: 0.33-0.74) were comparable to the dimensions of a rat femur which was also scanned. Cross-sectional properties were determined at 0.25 mm increments along the length of the phantom and femur. The table shows average error (+/- SD) from theory of Imax, Imin, and Theta) over the 12 orientations, calculated from raw and fully processed phantom images, as well as standard deviations about the mean for the femur scans. Processing of phantom scans increased agreement with theory, indicating improved accuracy. Smaller standard deviations with processing indicate increased precision and repeatability. Standard deviations for the femur are consistent with those of the phantom. We conclude that in conjunction with digital image enhancement, densitometry scans are suitable for non-destructive determination of areal properties of small animal bones of comparable size to our phantom, allowing prediction of Imax and Imin within 2.5% and Theta within a fraction of a degree. This method represents a considerable extension of current methods of analyzing bone tissue distribution in small animal bones.

Electrocardiographic features of patients with earthquake related posttraumatic stress disorder

PubMed Central

İlhan, Erkan; Kaplan, Abdullah; Güvenç, Tolga Sinan; Biteker, Murat; Karabulut, Evindar; Işıklı, Serhan

2013-01-01

AIM: To analyze electrocardiographic features of patients diagnosed with posttraumatic stress disorder (PTSD) after the Van-Erciş earthquake, with a shock measuring 7.2 on the Richter scale that took place in Turkey in October 2011. METHODS: Surface electrocardiograms of 12 patients with PTSD admitted to Van Erciş State Hospital (Van, Turkey) from February 2012 to May 2012 were examined. Psychiatric interviews of the sex and age matched control subjects, who had experienced the earthquake, confirmed the absence of any known diagnosable psychiatric conditions in the control group. RESULTS: A wide range of electrocardiogram (ECG) parameters, such as P-wave dispersion, QT dispersion, QT interval, Tpeak to Tend interval, intrinsicoid deflection durations and other traditional parameters were similar in both groups. There was no one with an abnormal P wave axis, short or long PR interval, long or short QT interval, negative T wave in lateral leads, abnormal T wave axis, abnormal left or right intrinsicoid deflection duration, low voltage, left bundle branch block, right bundle branch block, left posterior hemiblock, left or right axis deviation, left ventricular hypertrophy, right or left atrial enlargement and pathological q(Q) wave in either group. CONCLUSION: The study showed no direct effect of earthquake related PTSD on surface ECG in young patients. So, we propose that PTSD has no direct effect on surface ECG but may cause electrocardiographic changes indirectly by triggering atherosclerosis and/or contributing to the ongoing atherosclerotic process. PMID:23538549

75 FR 81125 - Drawbridge Operation Regulation; Sassafras River, Georgetown, MD

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-27

..., in Georgetown, MD. The deviation is necessary to facilitate mechanical repairs and gate replacement... facilitate mechanical repairs and barrier gate replacement. The Sassafras River Bridge (Route 213), at mile...

Establishment of left–right asymmetry in vertebrate development: the node in mouse embryos

PubMed Central

Komatsu, Yoshihiro

2014-01-01

Establishment of vertebrate left–right asymmetry is a critical process for normal embryonic development. After the discovery of genes expressed asymmetrically along the left–right axis in chick embryos in the mid 1990s, the molecular mechanisms responsible for left–right patterning in vertebrate embryos have been studied extensively. In this review article, we discuss the mechanisms by which the initial symmetry along the left–right axis is broken in the mouse embryo. We focus on the role of primary cilia and molecular mechanisms of ciliogenesis at the node when symmetry is broken and left–right asymmetry is established. The node is considered a signaling center for early mouse embryonic development, and the results we review here have led to a better understanding of how the node functions and establishes left–right asymmetry. PMID:23771646

Establishment of left-right asymmetry in vertebrate development: the node in mouse embryos.

PubMed

Komatsu, Yoshihiro; Mishina, Yuji

2013-12-01

Establishment of vertebrate left-right asymmetry is a critical process for normal embryonic development. After the discovery of genes expressed asymmetrically along the left-right axis in chick embryos in the mid 1990s, the molecular mechanisms responsible for left-right patterning in vertebrate embryos have been studied extensively. In this review article, we discuss the mechanisms by which the initial symmetry along the left-right axis is broken in the mouse embryo. We focus on the role of primary cilia and molecular mechanisms of ciliogenesis at the node when symmetry is broken and left-right asymmetry is established. The node is considered a signaling center for early mouse embryonic development, and the results we review here have led to a better understanding of how the node functions and establishes left-right asymmetry.

Switching modes in corticogenesis: mechanisms of neuronal subtype transitions and integration in the cerebral cortex

PubMed Central

Toma, Kenichi; Hanashima, Carina

2015-01-01

Information processing in the cerebral cortex requires the activation of diverse neurons across layers and columns, which are established through the coordinated production of distinct neuronal subtypes and their placement along the three-dimensional axis. Over recent years, our knowledge of the regulatory mechanisms of the specification and integration of neuronal subtypes in the cerebral cortex has progressed rapidly. In this review, we address how the unique cytoarchitecture of the neocortex is established from a limited number of progenitors featuring neuronal identity transitions during development. We further illuminate the molecular mechanisms of the subtype-specific integration of these neurons into the cerebral cortex along the radial and tangential axis, and we discuss these key features to exemplify how neocortical circuit formation accomplishes economical connectivity while maintaining plasticity and evolvability to adapt to environmental changes. PMID:26321900

Adversity-driven changes in hypothalamic-pituitary-adrenal axis functioning during adolescence. The trails study.

PubMed

Laceulle, Odilia M; Nederhof, Esther; van Aken, Marcel A G; Ormel, Johan

2017-11-01

The hypothalamic-pituitary-adrenal (HPA) axis has been proposed to be a key mechanism underlying the link between adversity and mental health, but longitudinal studies on adversity and HPA-axis functioning are scarce. Here, we studied adversity-driven changes in HPA-axis functioning during adolescence (N=141). HPA-axis functioning (basal cortisol, cortisol awakening response, anticipation of, reaction to and recovery after a stress task) was measured twice, at age 16 and 19. Adversity (i.e., social defeat and loss/illness) since age 16 was measured extensively with the Life Stress Interview at age 19. Adolescents who reported being exposed to social defeat showed increases in basal cortisol (ɳ 2 =0.029) and decreases in reaction to the stress task (ɳ 2 =0.030) from age 16-19, compared to their peers in the loss/illness and no stress group. The current study provides unique longitudinal data on the role of adversity in HPA-axis functioning. Evidence is provided that adversity can affect the body's neuroendocrine response to stress, dependent on the nature of both the HPA-measures and adverse events under study. Copyright © 2017 Elsevier Ltd. All rights reserved.

The role of the hypothalamus-pituitary-adrenal/interrenal axis in mediating predator-avoidance trade-offs.

PubMed

Harris, Breanna N; Carr, James A

2016-05-01

Maintaining energy balance and reproducing are important for fitness, yet animals have evolved mechanisms by which the hypothalamus-pituitary-adrenal/interrenal (HPA/HPI) axis can shut these activities off. While HPA/HPI axis inhibition of feeding and reproduction may have evolved as a predator defense, to date there has been no review across taxa of the causal evidence for such a relationship. Here we review the literature on this topic by addressing evidence for three predictions: that exposure to predators decreases reproduction and feeding, that exposure to predators activates the HPA/HPI axis, and that predator-induced activation of the HPA/HPI axis inhibits foraging and reproduction. Weight of evidence indicates that exposure to predator cues inhibits several aspects of foraging and reproduction. While the evidence from fish and mammals supports the hypothesis that predator cues activate the HPA/HPI axis, the existing data in other vertebrate taxa are equivocal. A causal role for the HPA axis in predator-induced suppression of feeding and reproduction has not been demonstrated to date, although many studies report correlative relationships between HPA activity and reproduction and/or feeding. Manipulation of HPA/HPI axis signaling will be required in future studies to demonstrate direct mediation of predator-induced inhibition of feeding and reproduction. Understanding the circuitry linking sensory pathways to their control of the HPA/HPI axis also is needed. Finally, the role that fear and anxiety pathways play in the response of the HPA axis to predator cues is needed to better understand the role that predators have played in shaping anxiety related behaviors in all species, including humans. Copyright © 2016 Elsevier Inc. All rights reserved.

Gut-central nervous system axis is a target for nutritional therapies.

PubMed

Pimentel, Gustavo D; Micheletti, Thayana O; Pace, Fernanda; Rosa, José C; Santos, Ronaldo V T; Lira, Fabio S

2012-04-10

Historically, in the 1950s, the chemist Linus Pauling established a relationship between decreased longevity and obesity. At this time, with the advent of studies involving the mechanisms that modulate appetite control, some researchers observed that the hypothalamus is the "appetite centre" and that peripheral tissues have important roles in the modulation of gut inflammatory processes and levels of hormones that control food intake. Likewise, the advances of physiological and molecular mechanisms for patients with obesity, type 2 diabetes mellitus, inflammatory bowel diseases, bariatric surgery and anorexia-associated diseases has been greatly appreciated by nutritionists. Therefore, this review highlights the relationship between the gut-central nervous system axis and targets for nutritional therapies.

Mechanical coupling for a rotor shaft assembly of dissimilar materials

DOEpatents

Shi, Jun [Glastonbury, CT; Bombara, David [New Hartford, CT; Green, Kevin E [Broad Brook, CT; Bird, Connic [Rocky Hill, CT; Holowczak, John [South Windsor, CT

2009-05-05

A mechanical coupling for coupling a ceramic disc member to a metallic shaft includes a first wedge clamp and a second wedge clamp. A fastener engages a threaded end of a tie-bolt to sandwich the ceramic disc between the wedge clamps. An axial spring is positioned between the fastener and the second wedge clamp to apply an axial preload along the longitudinal axis. Another coupling utilizes a rotor shaft end of a metallic rotor shaft as one wedge clamp. Still another coupling includes a solid ceramic rotor disc with a multiple of tie-bolts radially displaced from the longitudinal axis to exert the preload on the solid ceramic rotor disc.

Generation of mechanical oscillation applicable to vibratory rate gyroscopes

NASA Technical Reports Server (NTRS)

Lemkin, Mark A. (Inventor); Juneau, Thor N. (Inventor); Clark, William A. (Inventor); Roessig, Allen W. (Inventor)

2001-01-01

To achieve a drive-axis oscillation with improved frequency and amplitude stability, additional feedback loops are used to adjust force-feedback loop parameters. An amplitude-control loop measures oscillation amplitude, compares this value to the desired level, and adjusts damping of the mechanical sense-element to grow or shrink oscillation amplitude as appropriate. A frequency-tuning loop measures the oscillation frequency, compares this value with a highly stable reference, and adjusts the gain in the force-feedback loop to keep the drive-axis oscillation frequency at the reference value. The combined topology simultaneously controls both amplitude and frequency. Advantages of the combined topology include improved stability, fast oscillation start-up, low power consumption, and excellent shock rejection.

[The behavioral-neuroendocrine mechanism of development of homosexuality].

PubMed

Xue, Hui; Tai, Fa-Dao

2007-10-01

In this review, we primarily focus on the behavioral-neuroendocrine mechanism of development of homosexuality from genetic, neuroendocrine neuroanatomical and behavioral studies. Besides the influence of genetics and environment, sexual orientation was determined by the early perinatal hormone exposure. Gonadal steroidal hormone interacted with many neurotransmitters in individual development by hypothalamus pituitary adrenal axis and hypothalamus pituitary gonadal axis, which regulated the individual's sexual orientation. It was summarized here about the future directions on sexual orientation and demonstrated problems which would have to investigate next step. All these may be beneficial for our understanding of the homosexuality and paying attention to psychological and physiological health of homosexuality, which is useful to prevent the development of teenage homosexuality.

Use of Network Inference to Unravel the Mechanisms of Action and Specificity of Aromatase Inhibitors

EPA Science Inventory

The vertebrate hypothalamus-pituitary-gonadal (HPG) axis is controlled through various feedback mechanisms in order to maintain a dynamic homeostasis during changing environmental conditions, including exposure to chemical stressors. In this study, three aromatase inhibitors, fad...

What are the bias, imprecision, and limits of agreement for finding the flexion-extension plane of the knee with five tibial reference lines?

PubMed

Brar, Abheetinder S; Howell, Stephen M; Hull, Maury L

2016-06-01

Internal-external (I-E) malrotation of the tibial component is associated with poor function after total knee arthroplasty (TKA). Kinematically aligned (KA) TKA uses a functionally defined flexion-extension (F-E) tibial reference line, which is parallel to the F-E plane of the extended knee, to set I-E rotation of the tibial component. Sixty-two, three-dimensional bone models of normal knees were analyzed. We computed the bias (mean), imprecision (±standard deviation), and limits of agreement (mean±2 standard deviations) of the angle between five anatomically defined tibial reference lines used in mechanically aligned (MA) TKA and the F-E tibial reference line (+external). The following are the bias, imprecision, and limits of agreement of the angle between the F-E tibial reference line and 1) the tibial reference lines connecting the medial border (-2°±6°, -14° to 10°), medial 1/3 (6°±6°, -6° to 18°), and the most anterior point of the tibial tubercle (9°±4°, -1° to 17°) with the center of the posterior cruciate ligament, and 2) the tibial reference lines perpendicular to the posterior condylar axis of the tibia (-3°±4°, -11° to 5°), and a line connecting the centers of the tibial condyles (1°±4°, -7° to 9°). Based on these in vitro findings, it might be prudent to reconsider setting the I-E rotation of the tibial component to tibial reference lines that have bias, imprecision, and limits of agreement that fall outside the -7° to 10° range associated with high function after KA TKA. Copyright © 2016 Elsevier B.V. All rights reserved.

Using 1D theory to understand 3D stagnation of a wire-array Z pinch in the absence of radiation

NASA Astrophysics Data System (ADS)

Yu, Edmund

2015-11-01

Many high-energy-density systems implode towards the axis of symmetry, where it collides on itself, forming a hot plasma. However, experiments show these imploding plasmas develop three-dimensional (3D) structures. As a result, the plasma cannot completely dissipate its kinetic energy at stagnation, instead retaining significant 3D flow. A useful tool for understanding the effects of this residual flow is 3D simulation, but the amount and complexity of information can be daunting. To address this problem, we explore the connection between 3D simulation and one-dimensional (1D) theory. Such a connection, if it exists, is mutually beneficial: 1D theory can provide a clear picture of the underlying dynamics of 3D stagnation. On the other hand, deviations between theory and simulation suggest how 1D theory must be modified to account for 3D effects. In this work, we focus on a 3D, magnetohydrodynamic simulation of a compact wire-array Z pinch. To provide a simpler background against which to test our ideas, we artificially turn off radiation during the stagnation phase. Examination of the initial accumulation of mass on axis reveals oblique collision between jets, shock accretion, and vortex formation. Despite evidence for shock-dominated stagnation, a 1D shockless stagnation solution is more appropriate for describing the global dynamics, in that it reproduces the increase of on-axis density with time. However, the 1D solution must be modified to account for 3D effects: the flows suggest enhanced thermal transport as well as centrifugal force. Upon reaching peak compression, the stagnation transitions to a second phase, in which the high-pressure core on axis expands outward into the remaining imploding plasma. During this phase, a 1D shock solution describes the growth of the shock accretion region, as well as the decrease of on-axis density with time. However, the effect of 3D flows is still present: the on-axis temperature does not cool during expansion, which appears due to ``channels'' of plasma carrying heat to the core center. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockhead Martin Company, for the National Nuclear Security Administration under DE-AC04-94AL85000.

Precision grip responses to unexpected rotational perturbations scale with axis of rotation.

PubMed

De Gregorio, Michael; Santos, Veronica J

2013-04-05

It has been established that rapid, pulse-like increases in precision grip forces ("catch-up responses") are elicited by unexpected translational perturbations and that response latency and strength scale according to the direction of linear slip relative to the hand as well as gravity. To determine if catch-up responses are elicited by unexpected rotational perturbations and are strength-, axis-, and/or direction-dependent, we imposed step torque loads about each of two axes which were defined relative to the subject's hand: the distal-proximal axis away from and towards the subject's palm, and the grip axis which connects the two fingertips. Precision grip responses were dominated initially by passive mechanics and then by active, unimodal catch-up responses. First dorsal interosseous activity, marking the start of the catch-up response, began 71-89 ms after the onset of perturbation. The onset latency, shape, and duration (217-231 ms) of the catch-up response were not affected by the axis, direction, or magnitude of the rotational perturbation, while strength was scaled by axis of rotation and slip conditions. Rotations about the grip axis that tilted the object away from the palm and induced rotational slip elicited stronger catch-up responses than rotations about the distal-proximal axis that twisted the object between the digits. To our knowledge, this study is the first to investigate grip responses to unexpected torque loads and to show characteristic, yet axis-dependent, catch-up responses for conditions other than pure linear slip. Copyright © 2013 Elsevier Ltd. All rights reserved.

Turbulent current drive mechanisms

NASA Astrophysics Data System (ADS)

McDevitt, Christopher J.; Tang, Xian-Zhu; Guo, Zehua

2017-08-01

Mechanisms through which plasma microturbulence can drive a mean electron plasma current are derived. The efficiency through which these turbulent contributions can drive deviations from neoclassical predictions of the electron current profile is computed by employing a linearized Coulomb collision operator. It is found that a non-diffusive contribution to the electron momentum flux as well as an anomalous electron-ion momentum exchange term provide the most efficient means through which turbulence can modify the mean electron current for the cases considered. Such turbulent contributions appear as an effective EMF within Ohm's law and hence provide an ideal means for driving deviations from neoclassical predictions.

Afocal three-mirror anastigmat with zigzag optical axis for widened field of view and enlarged aperture

NASA Astrophysics Data System (ADS)

Li, Qi; Han, Lin; Jin, Yangming; Shen, Weimin

2016-10-01

In order to improve the detection accuracy and range of new generation of Forward Looking Infra-Red (FLIR) system for distant targets, its optical system, which usually consists of a fore afocal telescope and rear imaging lenses, is required to has wide spectral range, large entrance pupil aperture, and wide field of view (FOV). In this paper, a new afocal Three-Mirror Anastigmat (TMA) with widened field of view and high demagnification is suggested. Its mechanical structure remains coaxial, but it has zigzag optical axis through properly and slightly decentering and tilting of the three mirrors to avoid its secondary obscuration due to the third mirror as FOV increase. Compared with conventional off-axis TMA, the suggested zigzag-axis TMA is compact, easy-alignment and low-cost. The design method and optimum result of the suggested afocal TMA is presented. Its initial structural parameters are determined with its first-order relationship and primary aberration theory. Slight and proper decentration and tilt of each mirror is leaded in optimization so that its coaxial mechanical structure is held but attainable FOV and demagnification are respectively as wide and as high as possible. As an example, a 5.5-demagnification zigzag-axis afocal TMA with a wavelength range, an entrance pupil diameter, and FOV respectively from 3μm to 12μm, of 320mm, and 2×3.2 degrees and with a real exit pupil, is designed. Its imaging quality is diffraction limited. It is suitable for fore afocal telescope of the so-called third generation FLIR.

Axis switching and spreading of an asymmetric jet: Role of vorticity dynamics

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.

1994-01-01

The effects of vortex generators and periodic excitation on vorticity dynamics and the phenomenon of axis switching in a free asymmetric jet are studied experimentally. Most of the data reported are for a 3:1 rectangular jet at a Reynolds number of 450,000 and a Mach number of 0.31. The vortex generators are in the form of 'delta tabs', triangular shaped protrusions into the flow, placed at the nozzle exit. With suitable placement of the tabs, axis switching could be either stopped or augmented. Two mechanisms are identified governing the phenomenon. One, as described by previous researchers and referred to here as the omega(sub theta)-induced dynamics, is due to difference in induced velocities for different segments of a rolled up azimuthal vortical structure. The other, omega(sub x)-induced dynamics, is due to the induced velocities of streamwise vortex pairs in the flow. Both dynamics can be active in a natural asymmetric jet; the tendency for axis switching caused by the omega(sub theta)-induced dynamics may be, depending on the streamwise vorticity distribution, either resisted or enhanced by the omega(sub x)-induced dynamics. While this simple framework qualitatively explains the various observations made on axis switching, mechanisms actually in play may be much more complex. The two dynamics are not independent as the flow field is replete with both azimuthal and streamwise vortical structures which continually interact. Phase averaged flow field data for a periodically forced case, over a volume of the flow field, are presented and discussed in an effort to gain insight into the dynamics of these vortical structures.

Effect of Local Vibration and Passive Exercise on the Hormones and Neurotransmitters of Hypothalamic-Pituitary-Adrenal Axis in Hindlimb Unloading Rats

NASA Astrophysics Data System (ADS)

Luan, Huiqin; Huang, Yunfei; Li, Jian; Sun, Lianwen; Fan, Yubo

2018-04-01

Astronauts are severely affected by spaceflight-induced bone loss. Mechanical stimulation through exercise inhibits bone resorption and improves bone formation. Exercise and vibration can prevent the degeneration of the musculoskeletal system in tail-suspended rats, and long-term exercise stress will affect endocrine and immune systems that are prone to fatigue. However, the mechanisms through which exercise and vibration affect the endocrine system remain unknown. This study mainly aimed to investigate the changes in the contents of endocrine axis-related hormones and the effects of local vibration and passive exercise on hypothalamic-pituitary-adrenal (HPA) axis-related hormones in tail-suspended rats. A total of 32 Sprague-Dawley rats were randomly distributed into four groups (n = 8 per group): tail suspension (TS), TS + 35Hz vibration, TS + passive exercise, and control. The rats were placed on a passive exercise and local vibration regimen for 21 days. On day 22 of the experiment, the contents of corticotrophin-releasing hormone, adrenocorticotropic hormone, cortisol, and 5-hydroxytryptamine in the rats were quantified with kits in accordance with the manufacturer's instructions. Histomorphometry was applied to evaluate histological changes in the hypothalamus. Results showed that 35Hz local vibration cannot cause rats to remain in a stressed state and that it might not inhibit the function of the HPA axis. Therefore, we speculate that this local vibration intensity can protect the function of the HPA axis and helps tail-suspended rats to transition from stressed to adaptive state.

Paternal stress exposure alters sperm microRNA content and reprograms offspring HPA stress axis regulation

PubMed Central

Rodgers, Ali B.; Morgan, Christopher P.; Bronson, Stefanie L.; Revello, Sonia; Bale, Tracy L.

2013-01-01

Neuropsychiatric disease frequently presents with an underlying hypo- or hyper- reactivity of the HPA stress axis, suggesting an exceptional vulnerability of this circuitry to external perturbations. Parental lifetime exposures to environmental challenges are associated with increased offspring neuropsychiatric disease risk, and likely contribute to stress dysregulation. While maternal influences have been extensively examined, much less is known regarding the specific role of paternal factors. To investigate the potential mechanisms by which paternal stress may contribute to offspring hypothalamic-pituitary-adrenal (HPA) axis dysregulation, we exposed mice to six weeks of chronic stress prior to breeding. As epidemiological studies support variation in paternal germ cell susceptibility to reprogramming across the lifespan, male stress exposure occurred either throughout puberty or in adulthood. Remarkably, offspring of sires from both paternal stress groups displayed significantly reduced HPA axis stress responsivity. Gene set enrichment analyses in offspring stress regulating brain regions, the paraventricular nucleus (PVN) and the bed nucleus of stria terminalis (BNST), revealed global pattern changes in transcription suggestive of epigenetic reprogramming and consistent with altered offspring stress responsivity, including increased expression of glucocorticoid-responsive genes in the PVN. In examining potential epigenetic mechanisms of germ cell transmission, we found robust changes in sperm miRNA (miR) content, where nine specific miRs were significantly increased in both paternal stress groups. Overall, these results demonstrate that paternal experience across the lifespan can induce germ cell epigenetic reprogramming and impact offspring HPA stress axis regulation, and may therefore offer novel insight into factors influencing neuropsychiatric disease risk. PMID:23699511

Kinematics of Hooke universal joint robot wrists

NASA Technical Reports Server (NTRS)

Mckinney, William S., Jr.

1988-01-01

The singularity problem associated with wrist mechanisms commonly found on industrial manipulators can be alleviated by redesigning the wrist so that it functions as a three-axis gimbal system. This paper discussess the kinematics of gimbal robot wrists made of one and two Hooke universal joints. Derivations of the resolved rate motion control equations for the single and double Hooke universal joint wrists are presented using the three-axis gimbal system as a theoretical wrist model.

Isocaloric pair-fed high-carbohydrate diet induced more hepatic steatosis and inflammation than high-fat diet mediated by miR- 34a/SIRT1 axis in mice

USDA-ARS?s Scientific Manuscript database

To investigate the different effects of isocaloric high-fat diet (HFD) and high-carbohydrate diet (HCD) on hepatic steatosis and the underlying mechanisms, especially the role of microRNA- 34a/silent information regulator T1 (SIRT1) axis, C57BL/6J mice (n = 12/group) were isocaloric pair-fed with Li...

MEMSlab: A Practical MEMS Course for the Fabrication, Packaging, and Testing of a Single-Axis Accelerometer

ERIC Educational Resources Information Center

Grundbacher, R.; Hoetzel, J. E.; Hierold, C.

2009-01-01

A microelectro-mechanical systems (MEMS) laboratory course (MEMSlab) in the Mechanical and Process Engineering Department at the Swiss Federal Institute of Technology (ETH Zurich), is presented. The course has been taught for four years and has been attended primarily by Master's students from mechanical and electrical engineering; since fall…

CFD analysis of a Darrieus wind turbine

NASA Astrophysics Data System (ADS)

Niculescu, M. L.; Cojocaru, M. G.; Pricop, M. V.; Pepelea, D.; Dumitrache, A.; Crunteanu, D. E.

2017-07-01

The Darrieus wind turbine has some advantages over the horizontal-axis wind turbine. Firstly, its tip speed ratio is lower than that of the horizontal-axis wind turbine and, therefore, its noise is smaller, privileging their placement near populated areas. Secondly, the Darrieus wind turbine does needs no orientation mechanism with respect to wind direction in contrast to the horizontal-axis wind turbine. However, the efficiency of the Darrieus wind turbine is lower than that of the horizontal-axis wind turbine since its aerodynamics is much more complex. With the advances in computational fluids and computers, it is possible to simulate the Darrieus wind turbine more accurately to understand better its aerodynamics. For these reasons, the present papers deals with the computational aerodynamics of a Darrieus wind turbine applying the state of the art of CFD methods (anisotropic turbulence models, transition from laminar to turbulent, scale adaptive simulation) to better understand its unsteady behavior.

Forces directing germ-band extension in Drosophila embryos.

PubMed

Kong, Deqing; Wolf, Fred; Großhans, Jörg

2017-04-01

Body axis elongation by convergent extension is a conserved developmental process found in all metazoans. Drosophila embryonic germ-band extension is an important morphogenetic process during embryogenesis, by which the length of the germ-band is more than doubled along the anterior-posterior axis. This lengthening is achieved by typical convergent extension, i.e. narrowing the lateral epidermis along the dorsal-ventral axis and simultaneous extension along the anterior-posterior axis. Germ-band extension is largely driven by cell intercalation, whose directionality is determined by the planar polarity of the tissue and ultimately by the anterior-posterior patterning system. In addition, extrinsic tensile forces originating from the invaginating endoderm induce cell shape changes, which transiently contribute to germ-band extension. Here, we review recent progress in understanding of the role of mechanical forces in germ-band extension. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Role of the Hypothalamic-Pituitary-Adrenal Axis in Developmental Programming of Health and Disease

PubMed Central

Xiong, Fuxia; Zhang, Lubo

2012-01-01

Adverse environments during the fetal and neonatal development period may permanently program physiology and metabolism, and lead to increased risk of diseases in later life. Programming of the hypothalamic-pituitary-adrenal (HPA) axis is one of the key mechanisms that contribute to altered metabolism and response to stress. Programming of the HPA axis often involves epigenetic modification of the glucocorticoid receptor (GR) gene promoter, which influences tissue-specific GR expression patterns and response to stimuli. This review summarizes the current state of research on the HPA axis and programming of health and disease in the adult, focusing on the epigenetic regulation of GR gene expression patterns in response to fetal and neonatal stress. Aberrant GR gene expression patterns in the developing brain may have a significant negative impact on protection of the immature brain against hypoxic-ischemic encephalopathy in the critical period of development during and immediately after birth. PMID:23200813

Central precocious puberty: from physiopathological mechanisms to treatment.

PubMed

Chirico, V; Lacquaniti, A; Salpietro, V; Buemi, M; Salpietro, C; Arrigo, T

2014-01-01

Puberty is a complex, coordinated biological process with multiple levels of regulations. The timing of puberty varies greatly in children and it is influenced by environmental, endocrine and genetic factors. Precocious puberty (PP) is an important issue, affecting between 1 in 5.000-10.000 children. The physiopathological mechanism is still unknown. From an etiological point of view, PP may be subdivided into gonadotropin-releasing hormone (GnRH) -dependent and independent causes. GnRH-dependent PP, often called central precocious puberty (CPP), is based on hypothalamic-pituitary-gonadal axis activation associated with progressive pubertal development, accelerated growth rate and advancement of skeletal age. Conversely, peripheral precocious puberty (PPP) is related to sex steroid exposure, independently of hypothalamic-–pituitary-–gonadal (HPG) axis activation. Kisspeptins play a central role in the modulation of GnRH secretion with peripheral factors that influence the timing of puberty, such as adipokines and endocrine disrupting chemicals. Moreover, PP could be related to genetic disorders, involving pivotal genes of the HPG axis. The standard test used to verify HPG activity is the gonadotropin response to administered GnRH analogs. We describe the physiopathological mechanisms of PP and its clinical implications, analysing diagnostic flow-chart and new potential biomarkers that could reveal PP. An update of the current literature was also carried out regarding the recent novelty for treatment.