Sample records for rigid nephroscopy sufficient

  1. Concomitant treatment of ureteropelvic junction obstruction and renal calculi with robotic laparoscopic surgery and rigid nephroscopy.

    PubMed

    Zheng, Ji; Yan, Junan; Zhou, Zhansong; Chen, Zhiwen; Li, Xin; Pan, Jinhong; Li, Weibing

    2014-01-01

    The treatment of ureteropelvic junction obstruction (UPJO) and concomitant calculus poses a technically challenging situation. We present our experience with using rigid nephroscopy for renal calculi removal during robot-assisted pyeloplasy (RAP) for UPJO. From December 2010 to November 2012, 25 patients with UPJO had RAP at our institution; 9 of those had concurrent renal calculi, which were simultaneously treated with rigid nephroscopy. For stone extraction, a rigid ureteroscope was passed through an assistant trocar under laparoscopic vision directly into a previously created pyelotomy. The stones were extracted using a rigid grasper or stone basket through the rigid ureteroscope. For the removal of the stones within the upper and lower calyces, the rigid ureteroscope was introduced into the incised renal pelvis through robotic trocars if the "assistant trocar" route failed. Complete stone clearance was achieved in 8 of 9 patients. Residual calculi in 1 patient were removed with a single session of extracorporeal shock wave lithotripsy. At the mean follow-up of 10.2 months, no patients had obstruction or recurrent stones. The mean operative time was 187.1 minutes, which was 40.9 minutes longer than the mean operative time in patients without renal calculi. There was no significant difference in blood loss, hospital stay, complications, and success rates between patients with and without renal calculi. Our data suggest that the use of a concomitant rigid nephroscope and RAP is a safe and feasible option for the treatment of UPJO complicated with renal calculi. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Laparoscopic ureterolysis with simultaneous ureteroscopy and percutaneous nephroscopy for treating complex ureteral obstruction after failed endoscopic intervention: A technical report.

    PubMed

    Wang, Zhixiang; Liu, Bing; Gao, Xiaofeng; Bao, Yi; Wang, Yang; Ye, Huamao; Sun, Yinghao; Wang, Linhui

    2015-10-01

    Complex ureteral obstruction is refractory to conventional urological intervention. This report describes a case of laparoscopic ureterolysis with simultaneous ureteroscopy and percutaneous nephroscopy for treating complex ureteral obstruction. Right-side multiple ureteral stones and complicating ureteral obstruction failed an initial attempt of ureteroscopy lithotripsy with simultaneous percutaneous nephroscopy in a 23-year-old male. Laparoscopic ureterolysis with ureteroscopy and percutaneous nephroscopy was used simultaneously to dissect the periureteral adhesions with the patient placed in the Galdakao-modified supine Valdivia position. The ureter was incised to allow the insertion of a ureteral catheter through the twisted ureter, and a guide wire was advanced into the pelvis using ureteroscopy. A double-J stent was placed into the right-side ureter using antegrade percutaneous nephroscopy. The laparoendoscopic procedure lasted 330 min with an estimated bleeding volume of 100 mL. The patient underwent an uneventful postoperative course, and postoperative follow-up radiography confirmed good positioning of the double-J stent. The double-J stent was removed 3 months after operation. The patient remained asymptomatic within a 13-month follow-up period. Laparoscopic ureterolysis with simultaneous ureteroscopy and percutaneous nephroscopy is an effective and safe treatment option for complex ureteral obstruction.

  3. 21 CFR 876.5020 - External penile rigidity devices.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false External penile rigidity devices. 876.5020 Section 876.5020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... maintain sufficient penile rigidity for sexual intercourse. External penile rigidity devices include vacuum...

  4. 21 CFR 876.5020 - External penile rigidity devices.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false External penile rigidity devices. 876.5020 Section 876.5020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... maintain sufficient penile rigidity for sexual intercourse. External penile rigidity devices include vacuum...

  5. 21 CFR 876.5020 - External penile rigidity devices.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false External penile rigidity devices. 876.5020 Section 876.5020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... maintain sufficient penile rigidity for sexual intercourse. External penile rigidity devices include vacuum...

  6. 21 CFR 876.5020 - External penile rigidity devices.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false External penile rigidity devices. 876.5020 Section 876.5020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... maintain sufficient penile rigidity for sexual intercourse. External penile rigidity devices include vacuum...

  7. 21 CFR 876.5020 - External penile rigidity devices.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false External penile rigidity devices. 876.5020 Section 876.5020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... maintain sufficient penile rigidity for sexual intercourse. External penile rigidity devices include vacuum...

  8. Erosion of Embolization Coils into the Renal Collecting System: Removal with Prone Transradial Renal Arteriography and Nephroscopy.

    PubMed

    Srinivasa, Ravi N; Chick, Jeffrey Forris Beecham; Hage, Anthony; Ramamurthi, Aishu; Wolf, J Stuart; Gemmete, Joseph J; Dauw, Casey A

    2017-10-01

    Removal of embolization coils eroded into the renal collecting system poses a risk of hemorrhage, which may need to be addressed with arteriography and embolization at the time of treatment. The purpose of this report is to describe a novel approach, by which prone percutaneous nephroscopic coil retrieval is coupled with simultaneous prone transradial renal arterial access to mitigate this potential complication. A retrospective chart review of the electronic medical record systems was performed from January 2008 to May 2017 to identify patients who had undergone percutaneous removal of embolization coils eroded into the renal collecting system. Patients who had migration of embolization coils into the renal collecting system who were symptomatic with pain, hydronephrosis, or infection were considered for inclusion. Patients who had coil migration, but were asymptomatic were not offered removal. Patient demographics and case characteristics were examined as were operative outcomes. A total of three patients fulfilled the study criteria. Migrated embolization coils were able to be effectively removed in all patients. Of the patients, two underwent simultaneous prone transradial renal arteriography with placement of an occlusion balloon catheter into the segmental artery of interest. In one patient, significant arterial bleeding was encountered after coil removal, which was effectively addressed with simultaneous arteriography and glue embolization. Erosion of embolization coils into the renal collecting system, while rare, may be a significant long-term complication of coil embolization. Combining nephroscopy with prone transradial arteriography in preparation for procedure-associated hemorrhage may make removal of migrated coils safer.

  9. Dynamic Projection Mapping onto Deforming Non-Rigid Surface Using Deformable Dot Cluster Marker.

    PubMed

    Narita, Gaku; Watanabe, Yoshihiro; Ishikawa, Masatoshi

    2017-03-01

    Dynamic projection mapping for moving objects has attracted much attention in recent years. However, conventional approaches have faced some issues, such as the target objects being limited to rigid objects, and the limited moving speed of the targets. In this paper, we focus on dynamic projection mapping onto rapidly deforming non-rigid surfaces with a speed sufficiently high that a human does not perceive any misalignment between the target object and the projected images. In order to achieve such projection mapping, we need a high-speed technique for tracking non-rigid surfaces, which is still a challenging problem in the field of computer vision. We propose the Deformable Dot Cluster Marker (DDCM), a novel fiducial marker for high-speed tracking of non-rigid surfaces using a high-frame-rate camera. The DDCM has three performance advantages. First, it can be detected even when it is strongly deformed. Second, it realizes robust tracking even in the presence of external and self occlusions. Third, it allows millisecond-order computational speed. Using DDCM and a high-speed projector, we realized dynamic projection mapping onto a deformed sheet of paper and a T-shirt with a speed sufficiently high that the projected images appeared to be printed on the objects.

  10. In situ Neutron Diffraction during Casting: Determination of Rigidity Point in Grain Refined Al-Cu Alloys

    PubMed Central

    Drezet, Jean-Marie; Mireux, Bastien; Szaraz, Zoltan; Pirling, Thilo

    2014-01-01

    The rigidity temperature of a solidifying alloy is the temperature at which the solid plus liquid phases are sufficiently coalesced to transmit long range tensile strains and stresses. It determines the point at which thermally induced deformations start to generate internal stresses in a casting. As such, it is a key parameter in numerical modelling of solidification processes and in studying casting defects such as solidification cracking. This temperature has been determined in Al-Cu alloys using in situ neutron diffraction during casting in a dog bone shaped mould. In such a setup, the thermal contraction of the solidifying material is constrained and stresses develop at a hot spot that is irradiated by neutrons. Diffraction peaks are recorded every 11 s using a large detector, and their evolution allows for the determination of the rigidity temperatures. We measured rigidity temperatures equal to 557 °C and 548 °C, depending on cooling rate, for a grain refined Al-13 wt% Cu alloy. At high cooling rate, rigidity is reached during the formation of the eutectic phase and the solid phase is not sufficiently coalesced, i.e., strong enough, to avoid hot tear formation. PMID:28788507

  11. In situ Neutron Diffraction during Casting: Determination of Rigidity Point in Grain Refined Al-Cu Alloys.

    PubMed

    Drezet, Jean-Marie; Mireux, Bastien; Szaraz, Zoltan; Pirling, Thilo

    2014-02-12

    The rigidity temperature of a solidifying alloy is the temperature at which the solid plus liquid phases are sufficiently coalesced to transmit long range tensile strains and stresses. It determines the point at which thermally induced deformations start to generate internal stresses in a casting. As such, it is a key parameter in numerical modelling of solidification processes and in studying casting defects such as solidification cracking. This temperature has been determined in Al-Cu alloys using in situ neutron diffraction during casting in a dog bone shaped mould. In such a setup, the thermal contraction of the solidifying material is constrained and stresses develop at a hot spot that is irradiated by neutrons. Diffraction peaks are recorded every 11 s using a large detector, and their evolution allows for the determination of the rigidity temperatures. We measured rigidity temperatures equal to 557 °C and 548 °C, depending on cooling rate, for a grain refined Al-13 wt% Cu alloy. At high cooling rate, rigidity is reached during the formation of the eutectic phase and the solid phase is not sufficiently coalesced, i.e. , strong enough, to avoid hot tear formation.

  12. Physical pendulum—a simple experiment can give comprehensive information about a rigid body

    NASA Astrophysics Data System (ADS)

    Kladivová, Mária; Mucha, L'ubomír

    2014-03-01

    A simple experiment with a physical pendulum examining some aspects of rigid body motion is presented in this paper. The experiment consists of measuring the period of oscillation of a rod with non-homogeneous mass distribution used as a physical pendulum, dependent upon the position of the pivot axis. The obtained dependence provides sufficient information to calculate the position of the centre of mass, moment of inertia of the rigid body and local gravitational acceleration. This experiment is intended for secondary school and undergraduate students.

  13. Rigid particulate matter sensor

    DOEpatents

    Hall, Matthew [Austin, TX

    2011-02-22

    A sensor to detect particulate matter. The sensor includes a first rigid tube, a second rigid tube, a detection surface electrode, and a bias surface electrode. The second rigid tube is mounted substantially parallel to the first rigid tube. The detection surface electrode is disposed on an outer surface of the first rigid tube. The detection surface electrode is disposed to face the second rigid tube. The bias surface electrode is disposed on an outer surface of the second rigid tube. The bias surface electrode is disposed to face the detection surface electrode on the first rigid tube. An air gap exists between the detection surface electrode and the bias surface electrode to allow particulate matter within an exhaust stream to flow between the detection and bias surface electrodes.

  14. Rigidity and retention of ceramic root canal posts.

    PubMed

    Purton, D G; Love, R M; Chandler, N P

    2000-01-01

    Ceramic root-canal posts offer potential advantages over other types with respect to aesthetics and biocompatibility. Any post must be sufficiently rigid and retentive to withstand functional forces. Ceraposts (1.2 mm coronal diameter, ceramic, tapering, smooth posts) and Paraposts (1.25 mm, stainless-steel, parallel, serrated posts) were tested for rigidity by means of a three-point bending test. To test retention in roots, ceramic posts were cemented using one of three protocols: (1) glass-ionomer cement, (2) silane coupling agent and resin cement, or (3) sandblasted post surface, silane coupling agent, and resin cement. Stainless-steel posts were cemented with resin. The tensile force required to dislodge the posts, following four weeks of storage in water, was recorded. Data were compared using Student's t-test and Mann-Whitney U analysis. Ceraposts were significantly more rigid than Paraposts (p < 0.001). Paraposts cemented with resin were significantly more strongly retained than Ceraposts following any cementation protocol (p < 0.001). Retention of the ceramic posts was significantly greater with a silane coupling agent and resin cement than with glass-ionomer cement (p < 0.001). Sandblasting the ceramic posts produced variable results and needs further investigation before it could be recommended.

  15. Determination of Coherency and Rigidity Temperatures in Al-Cu Alloys Using In Situ Neutron Diffraction During Casting

    NASA Astrophysics Data System (ADS)

    Drezet, Jean-Marie; Mireux, Bastien; Szaraz, Zoltan; Pirling, Thilo

    2014-08-01

    The rigidity temperature of a solidifying alloy is the temperature at which the solid phase is sufficiently coalesced to transmit tensile stress. It is a major input parameter in numerical modeling of solidification processes as it defines the point at which thermally induced deformations start to generate internal stresses in a casting. This temperature has been determined for an Al-13 wt.% Cu alloy using in situ neutron diffraction during casting in a dog-bone-shaped mold. This setup allows the sample to build up internal stress naturally as its contraction is not possible. The cooling on both sides of the mold induces a hot spot at the middle of the sample that is irradiated by neutrons. Diffraction patterns are recorded every 11 s using a large detector, and the very first change of diffraction angles allows for the determination of the rigidity temperature. We measured rigidity temperatures equal to 557°C and 548°C depending on the cooling rate for grain refined Al-13 wt.% Cu alloys. At a high cooling rate, rigidity is reached during the formation of the eutectic phase. In this case, the solid phase is not sufficiently coalesced to sustain tensile load and thus cannot avoid hot tear formation.

  16. Understanding geological processes: Visualization of rigid and non-rigid transformations

    NASA Astrophysics Data System (ADS)

    Shipley, T. F.; Atit, K.; Manduca, C. A.; Ormand, C. J.; Resnick, I.; Tikoff, B.

    2012-12-01

    Visualizations are used in the geological sciences to support reasoning about structures and events. Research in cognitive sciences offers insights into the range of skills of different users, and ultimately how visualizations might support different users. To understand the range of skills needed to reason about earth processes we have developed a program of research that is grounded in the geosciences' careful description of the spatial and spatiotemporal patterns associated with earth processes. In particular, we are pursuing a research program that identifies specific spatial skills and investigates whether and how they are related to each other. For this study, we focus on a specific question: Is there an important distinction in the geosciences between rigid and non-rigid deformation? To study a general spatial thinking skill we employed displays with non-geological objects that had been altered by rigid change (rotation), and two types of non-rigid change ("brittle" (or discontinuous) and "ductile" (or continuous) deformation). Disciplinary scientists (geosciences and chemistry faculty), and novices (non-science faculty and undergraduate psychology students) answered questions that required them to visualize the appearance of the object before the change. In one study, geologists and chemists were found to be superior to non-science faculty in reasoning about rigid rotations (e.g., what an object would look like from a different perspective). Geologists were superior to chemists in reasoning about brittle deformations (e.g., what an object looked like before it was broken - here the object was a word cut into many fragments displaced in different directions). This finding is consistent with two hypotheses: 1) Experts are good at visualizing the types of changes required for their domain; and 2) Visualization of rigid and non-rigid changes are not the same skill. An additional important finding is that there was a broad range of skill in both rigid and non-rigid

  17. Preparation of a micropatterned rigid-soft composite substrate for probing cellular rigidity sensing.

    PubMed

    Wong, Stephanie; Guo, Wei-hui; Hoffecker, Ian; Wang, Yu-li

    2014-01-01

    Substrate rigidity has been recognized as an important property that affects cellular physiology and functions. While the phenomenon has been well recognized, understanding the underlying mechanism may be greatly facilitated by creating a microenvironment with designed rigidity patterns. This chapter describes in detail an optimized method for preparing substrates with micropatterned rigidity, taking advantage of the ability to dehydrate polyacrylamide gels for micropatterning with photolithography, and subsequently rehydrate the gel to regain the original elastic state. While a wide range of micropatterns may be prepared, typical composite substrates consist of micron-sized islands of rigid photoresist grafted on the surface of polyacrylamide hydrogels of defined rigidity. These islands are displaced by cellular traction forces, for a distance determined by the size of the island, the rigidity of the underlying hydrogel, and the magnitude of traction forces. Domains of rigidity may be created using this composite material to allow systematic investigations of rigidity sensing and durotaxis. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. A simple method for fabricating microwire tetrode with sufficient rigidity and integrity without a heat-fusing process.

    PubMed

    Liao, Yi-Fang; Tsai, Meng-Li; Yen, Chen-Tung; Cheng, Chiung-Hsiang

    2011-02-15

    Heat-fusing is a common process for fabricating microwire tetrodes. However, it is time-consuming, and the high-temperature treatment can easily cause the insulation of the microwire to overheat leading to short circuits. We herein provide a simple, fast method to fabricate microwire tetrodes without the heat-fusion process. By increasing the twisting density, we were able to fabricate tetrodes with good rigidity and integrity. This kind of tetrode showed good recording quality, penetrated the brain surface easily, and remained intact after chronic implantation. This method requires only general laboratory tools and is relatively simple even for inexperienced workers. © 2010 Elsevier B.V. All rights reserved.

  19. Geometry and the onset of rigidity in a disordered network

    NASA Astrophysics Data System (ADS)

    Vermeulen, Mathijs F. J.; Bose, Anwesha; Storm, Cornelis; Ellenbroek, Wouter G.

    2017-11-01

    Disordered spring networks that are undercoordinated may abruptly rigidify when sufficient strain is applied. Since the deformation in response to applied strain does not change the generic quantifiers of network architecture, the number of nodes and the number of bonds between them, this rigidity transition must have a geometric origin. Naive, degree-of-freedom-based mechanical analyses such as the Maxwell-Calladine count or the pebble game algorithm overlook such geometric rigidity transitions and offer no means of predicting or characterizing them. We apply tools that were developed for the topological analysis of zero modes and states of self-stress on regular lattices to two-dimensional random spring networks and demonstrate that the onset of rigidity, at a finite simple shear strain γ★, coincides with the appearance of a single state of self-stress, accompanied by a single floppy mode. The process conserves the topologically invariant difference between the number of zero modes and the number of states of self-stress but imparts a finite shear modulus to the spring network. Beyond the critical shear, the network acquires a highly anisotropic elastic modulus, resisting further deformation most strongly in the direction of the rigidifying shear. We confirm previously reported critical scaling of the corresponding differential shear modulus. In the subcritical regime, a singular value decomposition of the network's compatibility matrix foreshadows the onset of rigidity by way of a continuously vanishing singular value corresponding to the nascent state of self-stress.

  20. Chromatin histone modifications and rigidity affect nuclear morphology independent of lamins

    PubMed Central

    Stephens, Andrew D.; Liu, Patrick Z.; Banigan, Edward J.; Almassalha, Luay M.; Backman, Vadim; Adam, Stephen A.; Goldman, Robert D.; Marko, John F.

    2018-01-01

    Nuclear shape and architecture influence gene localization, mechanotransduction, transcription, and cell function. Abnormal nuclear morphology and protrusions termed “blebs” are diagnostic markers for many human afflictions including heart disease, aging, progeria, and cancer. Nuclear blebs are associated with both lamin and chromatin alterations. A number of prior studies suggest that lamins dictate nuclear morphology, but the contributions of altered chromatin compaction remain unclear. We show that chromatin histone modification state dictates nuclear rigidity, and modulating it is sufficient to both induce and suppress nuclear blebs. Treatment of mammalian cells with histone deacetylase inhibitors to increase euchromatin or histone methyltransferase inhibitors to decrease heterochromatin results in a softer nucleus and nuclear blebbing, without perturbing lamins. Conversely, treatment with histone demethylase inhibitors increases heterochromatin and chromatin nuclear rigidity, which results in reduced nuclear blebbing in lamin B1 null nuclei. Notably, increased heterochromatin also rescues nuclear morphology in a model cell line for the accelerated aging disease Hutchinson–Gilford progeria syndrome caused by mutant lamin A, as well as cells from patients with the disease. Thus, chromatin histone modification state is a major determinant of nuclear blebbing and morphology via its contribution to nuclear rigidity. PMID:29142071

  1. Non-rigid Motion Correction in 3D Using Autofocusing with Localized Linear Translations

    PubMed Central

    Cheng, Joseph Y.; Alley, Marcus T.; Cunningham, Charles H.; Vasanawala, Shreyas S.; Pauly, John M.; Lustig, Michael

    2012-01-01

    MR scans are sensitive to motion effects due to the scan duration. To properly suppress artifacts from non-rigid body motion, complex models with elements such as translation, rotation, shear, and scaling have been incorporated into the reconstruction pipeline. However, these techniques are computationally intensive and difficult to implement for online reconstruction. On a sufficiently small spatial scale, the different types of motion can be well-approximated as simple linear translations. This formulation allows for a practical autofocusing algorithm that locally minimizes a given motion metric – more specifically, the proposed localized gradient-entropy metric. To reduce the vast search space for an optimal solution, possible motion paths are limited to the motion measured from multi-channel navigator data. The novel navigation strategy is based on the so-called “Butterfly” navigators which are modifications to the spin-warp sequence that provide intrinsic translational motion information with negligible overhead. With a 32-channel abdominal coil, sufficient number of motion measurements were found to approximate possible linear motion paths for every image voxel. The correction scheme was applied to free-breathing abdominal patient studies. In these scans, a reduction in artifacts from complex, non-rigid motion was observed. PMID:22307933

  2. Bang-Bang Practical Stabilization of Rigid Bodies

    NASA Astrophysics Data System (ADS)

    Serpelloni, Edoardo

    In this thesis, we study the problem of designing a practical stabilizer for a rigid body equipped with a set of actuators generating only constant thrust. Our motivation stems from the fact that modern space missions are required to accurately control the position and orientation of spacecraft actuated by constant-thrust jet-thrusters. To comply with the performance limitations of modern thrusters, we design a feedback controller that does not induce high-frequency switching of the actuators. The proposed controller is hybrid and it asymptotically stabilizes an arbitrarily small compact neighborhood of the target position and orientation of the rigid body. The controller is characterized by a hierarchical structure comprising of two control layers. At the low level of the hierarchy, an attitude controller stabilizes the target orientation of the rigid body. At the high level, after the attitude controller has steered the rigid body sufficiently close to its desired orientation, a position controller stabilizes the desired position. The size of the neighborhood being stabilized by the controller can be adjusted via a proper selection of the controller parameters. This allows us to stabilize the rigid body to virtually any degree of accuracy. It is shown that the controller, even in the presence of measurement noise, does not induce high-frequency switching of the actuators. The key component in the design of the controller is a hybrid stabilizer for the origin of double-integrators affected by bounded external perturbations. Specifically, both the position and the attitude stabilizers consist of multiple copies of such a double-integrator controller. The proposed controller is applied to two realistic spacecraft control problems. First, we apply the position controller to the problem of stabilizing the relative position between two spacecraft flying in formation in the vicinity of the L2 libration point of the Sun-Earth system as a part of a large space telescope

  3. EGFR and HER2 activate rigidity sensing only on rigid matrices

    NASA Astrophysics Data System (ADS)

    Saxena, Mayur; Liu, Shuaimin; Yang, Bo; Hajal, Cynthia; Changede, Rishita; Hu, Junqiang; Wolfenson, Haguy; Hone, James; Sheetz, Michael P.

    2017-07-01

    Epidermal growth factor receptor (EGFR) interacts with integrins during cell spreading and motility, but little is known about the role of EGFR in these mechanosensing processes. Here we show, using two different cell lines, that in serum- and EGF-free conditions, EGFR or HER2 activity increase spreading and rigidity-sensing contractions on rigid, but not soft, substrates. Contractions peak after 15-20 min, but diminish by tenfold after 4 h. Addition of EGF at that point increases spreading and contractions, but this can be blocked by myosin-II inhibition. We further show that EGFR and HER2 are activated through phosphorylation by Src family kinases (SFK). On soft surfaces, neither EGFR inhibition nor EGF stimulation have any effect on cell motility. Thus, EGFR or HER2 can catalyse rigidity sensing after associating with nascent adhesions under rigidity-dependent tension downstream of SFK activity. This has broad implications for the roles of EGFR and HER2 in the absence of EGF both for normal and cancerous growth.

  4. EGFR and HER2 Activate Rigidity Sensing Only on Rigid Matrices

    PubMed Central

    Saxena, Mayur; Liu, Shuaimin; Yang, Bo; Hajal, Cynthia; Changede, Rishita; Hu, Junqiang

    2017-01-01

    Epidermal growth factor receptor (EGFR) interacts with integrins during cell spreading and motility, but little is known about the role of EGFR in these mechanosensing processes. Here we show, using two different cell lines, that in serum- and EGF-free conditions, EGFR or HER2 activity increase spreading and rigidity-sensing contractions on rigid, but not soft, substrates. Contractions peak after 15–20 min, but diminish by 10-fold after 4 hours. Addition of EGF at that point increases spreading and contractions, but this can be blocked by myosin-II inhibition. We further show that EGFR and HER2 are activated through phosphorylation by Src family kinases (SFK). On soft surfaces, neither EGFR inhibition nor EGF stimulation have any effect on cell motility. Thus, EGFR or HER2 can catalyse rigidity sensing after associating with nascent adhesions under rigidity-dependent tension downstream of SFK activity. This has broad implications for the roles of EGFR and HER2 in absence of EGF both for normal and cancerous growth. PMID:28459445

  5. Rigidly foldable origami gadgets and tessellations

    PubMed Central

    Evans, Thomas A.; Lang, Robert J.; Magleby, Spencer P.; Howell, Larry L.

    2015-01-01

    Rigidly foldable origami allows for motion where all deflection occurs at the crease lines and facilitates the application of origami in materials other than paper. In this paper, we use a recently discovered method for determining rigid foldability to identify existing flat-foldable rigidly foldable tessellations, which are also categorized. We introduce rigidly foldable origami gadgets which may be used to modify existing tessellations or to create new tessellations. Several modified and new rigidly foldable tessellations are presented. PMID:26473037

  6. Hydrodynamics of suspensions of passive and active rigid particles: a rigid multiblob approach

    DOE PAGES

    Usabiaga, Florencio Balboa; Kallemov, Bakytzhan; Delmotte, Blaise; ...

    2016-01-12

    We develop a rigid multiblob method for numerically solving the mobility problem for suspensions of passive and active rigid particles of complex shape in Stokes flow in unconfined, partially confined, and fully confined geometries. As in a number of existing methods, we discretize rigid bodies using a collection of minimally resolved spherical blobs constrained to move as a rigid body, to arrive at a potentially large linear system of equations for the unknown Lagrange multipliers and rigid-body motions. Here we develop a block-diagonal preconditioner for this linear system and show that a standard Krylov solver converges in a modest numbermore » of iterations that is essentially independent of the number of particles. Key to the efficiency of the method is a technique for fast computation of the product of the blob-blob mobility matrix and a vector. For unbounded suspensions, we rely on existing analytical expressions for the Rotne-Prager-Yamakawa tensor combined with a fast multipole method (FMM) to obtain linear scaling in the number of particles. For suspensions sedimented against a single no-slip boundary, we use a direct summation on a graphical processing unit (GPU), which gives quadratic asymptotic scaling with the number of particles. For fully confined domains, such as periodic suspensions or suspensions confined in slit and square channels, we extend a recently developed rigid-body immersed boundary method by B. Kallemov, A. P. S. Bhalla, B. E. Griffith, and A. Donev (Commun. Appl. Math. Comput. Sci. 11 (2016), no. 1, 79-141) to suspensions of freely moving passive or active rigid particles at zero Reynolds number. We demonstrate that the iterative solver for the coupled fluid and rigid-body equations converges in a bounded number of iterations regardless of the system size. In our approach, each iteration only requires a few cycles of a geometric multigrid solver for the Poisson equation, and an application of the block-diagonal preconditioner

  7. Tile-based rigidization surface parametric design study

    NASA Astrophysics Data System (ADS)

    Giner Munoz, Laura; Luntz, Jonathan; Brei, Diann; Kim, Wonhee

    2018-03-01

    Inflatable technologies have proven useful in consumer goods as well as in more recent applications including civil structures, aerospace, medical, and robotics. However, inflatable technologies are typically lacking in their ability to provide rigid structural support. Particle jamming improves upon this by providing structures which are normally flexible and moldable but become rigid when air is removed. Because these are based on an airtight bladder filled with loose particles, they always occupy the full volume of its rigid state, even when not rigidized. More recent developments in layer jamming have created thin, compact rigidizing surfaces replacing the loose volume of particles with thinly layered surface materials. Work in this area has been applied to several specific applications with positive results but have not generally provided the broader understanding of the rigidization performance as a function of design parameters required for directly adapting layer rigidization technology to other applications. This paper presents a parametric design study of a new layer jamming vacuum rigidization architecture: tile-based vacuum rigidization. This form of rigidization is based on layers of tiles contained within a thin vacuum bladder which can be bent, rolled, or otherwise compactly stowed, but when deployed flat, can be vacuumed and form a large, flat, rigid plate capable of supporting large forces both localized and distributed over the surface. The general architecture and operation detailing rigidization and compliance mechanisms is introduced. To quantitatively characterize the rigidization behavior, prototypes rigidization surfaces are fabricated and an experimental technique is developed based on a 3-point bending test. Performance evaluation metrics are developed to describe the stiffness, load-bearing capacity, and internal slippage of tested prototypes. A set of experimental parametric studies are performed to better understand the impact of

  8. CHEMICAL RIGIDIZATION OF EXPANDABLE STRUCTURES.

    DTIC Science & Technology

    The objective of this program was to develop a chemical rigidization process that could be activated by an on-command mechanism and be capable of...and rigidized in the high vacuum facilities atWright-Patterson AFB, Ohio and were delivered to the Air Force. A fail-safe chemical rigidization system...have been varied from fifteen minutes to two hours. The chemical system, a vinyl-type monomer, has exhibited a sustained shelf-life, under ambient

  9. Rigidity of lattice domes

    NASA Technical Reports Server (NTRS)

    Savelyev, V. A.

    1979-01-01

    The means of ensuring total rigidity of lattice domes, using comparison with solid shells of 1-3 layers are discussed. Irregularities of manufacture, processing, and other factors are considered, as they relate to diminution of rigidity. The discussion uses the concepts of upper and lower critical loads on the structure in question.

  10. Mooring and ground handling rigid airships

    NASA Technical Reports Server (NTRS)

    Walker, H., Jr.

    1975-01-01

    The problems of mooring and ground handling rigid airships are discussed. A brief history of Mooring and Ground Handling Rigid Airships from July 2, 1900 through September 1, 1939 is included. Also a brief history of ground handling developments with large U. S. Navy nonrigid airships between September 1, 1939 and August 31, 1962 is included wherein developed equipment and techniques appear applicable to future large rigid airships. Finally recommendations are made pertaining to equipment and procedures which appear desirable and feasible for future rigid airship programs.

  11. Persistence of fan-shaped keratocytes is a matrix-rigidity-dependent mechanism that requires α5β1 integrin engagement.

    PubMed

    Riaz, Maryam; Versaevel, Marie; Mohammed, Danahe; Glinel, Karine; Gabriele, Sylvain

    2016-09-28

    Despite the importance of matrix rigidity on cell functions, many aspects of the mechanosensing process in highly migratory cells remain elusive. Here, we studied the migration of highly motile keratocytes on culture substrates with similar biochemical properties and rigidities spanning the range between soft tissues (~kPa) and stiff culture substrates (~GPa). We show that morphology, polarization and persistence of motile keratocytes are regulated by the matrix stiffness over seven orders of magnitude, without changing the cell spreading area. Increasing the matrix rigidity leads to more F-actin in the lamellipodia and to the formation of mature contractile actomyosin fibers that control the cell rear retraction. Keratocytes remain rounded and form nascent adhesions on compliant substrates, whereas large and uniformly distributed focal adhesions are formed on fan-shaped keratocytes migrating on rigid surfaces. By combining poly-L-lysine, fibronectin and vitronectin coatings with selective blocking of α v β 3 or α 5 β 1 integrins, we show that α V β 3 integrins permit the spreading of keratocytes but are not sufficient for polarization and rigidity sensing that require the engagement of α 5 β 1 integrins. Our study demonstrates a matrix rigidity-dependent regulation of the directional persistence in motile keratocytes and refines the role of α v β 3 and α 5 β 1 integrins in the molecular clutch model.

  12. Rigid and non-rigid micro-plates: Philippines and Myanmar-Andaman case studies

    NASA Astrophysics Data System (ADS)

    Rangin, Claude

    2016-01-01

    Generally, tectonic plates are considered as rigid. Oblique plate convergence favors the development of micro-plates along the converging boundaries. The north-south-trending Philippines archipelago (here named Philippine Mobile Belt, PMB), a few hundreds kilometers wide, is one of such complex tectonic zones. We show here that it is composed of rigid rotating crustal blocks (here called platelets). In Myanmar, the northernmost tip of the Sumatra-Andaman subduction system is another complex zone made of various crustal blocks in-between convergent plates. Yet, contrary to PMB, it sustains internal deformation with platelet buckling, altogether indicative of a non-rigid behavior. Therefore, the two case studies, Philippine Mobile Belt and Myanmar-Andaman micro-plate (MAS), illustrate the complexity of micro-plate tectonics and kinematics at convergent plate boundaries.

  13. Organically Modified Nanoclay-Reinforced Rigid Polyurethane Films

    NASA Astrophysics Data System (ADS)

    Park, Yong Tae; Qian, Yuqiang; Lindsay, Chris; Stein, Andreas; Macosko, Christopher

    2012-02-01

    The nanodispersion of vermiculite in polyurethanes was investigated to produce organoclay-reinforced rigid gas barrier films. Reducing gas transport can improve the insulation performance of closed cell polyurethane foam. In a previous study, the dispersion of vermiculite in polyurethanes without organic modification was not sufficient due to the non-uniform dispersion morphology. When vermiculite was modified by cation exchange with long-chain quaternary ammonium cations, the dispersion in methylene diphenyl diisocyanate (MDI) was significantly improved. Dispersion was improved by combining high intensity dispersive mixing with efficient distributive mixing. Polymerization conditions were also optimized in order to provide a high state of nanodispersion in the polyurethane nanocomposite. The dispersions were characterized using rheological, microscopic and scattering/diffraction techniques. The final nanocomposites showed enhancement of mechanical properties and reduction in permeability to carbon dioxide at low clay concentration (around 2 wt percent).

  14. Large-strain, rigid-to-rigid deformation of bistable electroactive polymers

    NASA Astrophysics Data System (ADS)

    Yu, Zhibin; Yuan, Wei; Brochu, Paul; Chen, Bin; Liu, Zhitian; Pei, Qibing

    2009-11-01

    Thermoplastic poly(tert-butyl acrylate) (PTBA) is reported as an electroactive polymer that is rigid at ambient conditions and turns into a dielectric elastomer above a transition temperature. In the rubbery state, a PTBA thin film can be electrically actuated to strains up to 335% in area expansion. The calculated actuation pressure is 3.2 MPa. The actuation is made bistable by cooling to below glass transition temperature. The PTBA represents the bistable electroactive polymer (BSEP) that can be actuated to various largely strained, rigid shapes. The application of the BSEP for refreshable Braille display, an active tactile display, is also demonstrated.

  15. MnPAVE-Rigid 2.0

    DOT National Transportation Integrated Search

    2018-05-01

    This project implemented additional features into MnPAVE-Rigid, leading to a new version of MnDOTs rigid pavement design software. The database of American Association of State Highway Transportation Officers (AASHTO) mechanistic-empirical (M-E) p...

  16. Rigidity of Glasses and Macromolecules

    NASA Astrophysics Data System (ADS)

    Thorpe, M. F.

    1998-03-01

    The simple yet powerful ideas of percolation theory have found their way into many different areas of research. In this talk we show how RIGIDITY PERCOLATION can be studied at a similar level of sophistication, using a powerful new program THE PEBBLE GAME (D. J. Jacobs and M. F. Thorpe, Phys. Rev. E) 53, 3682 (1996). that uses an integer algorithm. This program can analyse the rigidity of two and three dimensional networks containing more than one million bars and joints. We find the total number of floppy modes, and find the critical behavior as the network goes from floppy to rigid as more bars are added. We discuss the relevance of this work to network glasses, and how it relates to experiments that involve the mechanical properties like hardness and elasticity of covalent glassy networks like Ge_xAs_ySe_1-x-y and dicuss recent experiments that suggest that the rigidity transition may be first order (Xingwei Feng, W. J.Bresser and P. Boolchand, Phys. Rev. Lett 78), 4422 (1997).. This approach is also useful in macromolecules and proteins, where detailed information about the rigid domain structure can be obtained.

  17. Rigidity-tuning conductive elastomer

    NASA Astrophysics Data System (ADS)

    Shan, Wanliang; Diller, Stuart; Tutcuoglu, Abbas; Majidi, Carmel

    2015-06-01

    We introduce a conductive propylene-based elastomer (cPBE) that rapidly and reversibly changes its mechanical rigidity when powered with electrical current. The elastomer is rigid in its natural state, with an elastic (Young’s) modulus of 175.5 MPa, and softens when electrically activated. By embedding the cPBE in an electrically insulating sheet of polydimethylsiloxane (PDMS), we create a cPBE-PDMS composite that can reversibly change its tensile modulus between 37 and 1.5 MPa. The rigidity change takes ˜6 s and is initiated when a 100 V voltage drop is applied across the two ends of the cPBE film. This magnitude of change in elastic rigidity is similar to that observed in natural skeletal muscle and catch connective tissue. We characterize the tunable load-bearing capability of the cPBE-PDMS composite with a motorized tensile test and deadweight experiment. Lastly, we demonstrate the ability to control the routing of internal forces by embedding several cPBE-PDMS ‘active tendons’ into a soft robotic pneumatic bending actuator. Selectively activating the artificial tendons controls the neutral axis and direction of bending during inflation.

  18. Rigid aggregates: theory and applications

    NASA Astrophysics Data System (ADS)

    Richardson, D. C.

    2005-08-01

    Numerical models employing ``perfect'' self-gravitating rubble piles that consist of monodisperse rigid spheres with configurable contact dissipation have been used to explore collisional and rotational disruption of gravitational aggregates. Applications of these simple models include numerical simulations of planetesimal evolution, asteroid family formation, tidal disruption, and binary asteroid formation. These studies may be limited by the idealized nature of the rubble pile model, since perfect identical spheres stack and shear in a very specific, possibly over-idealized way. To investigate how constituent properties affect the overall characteristics of a gravitational aggregate, particularly its failure modes, we have generalized our numerical code to model colliding, self-gravitating, rigid aggregates made up of variable-size spheres. Euler's equation of rigid-body motion in the presence of external torques are implemented, along with a self-consistent prescription for handling non-central impacts. Simple rules for sticking and breaking are also included. Preliminary results will be presented showing the failure modes of gravitational aggregates made up of smaller, rigid, non-idealized components. Applications of this new capability include more realistic aggregate models, convenient modeling of arbitrary rigid shapes for studies of the stability of orbiting companions (replacing one or both bodies with rigid aggregates eliminates expensive interparticle collisions while preserving the shape, spin, and gravity field of the bodies), and sticky particle aggregation in dense planetary rings. This material is based upon work supported by the National Aeronautics and Space Administration under Grant No. NAG511722 issued through the Office of Space Science and by the National Science Foundation under Grant No. AST0307549.

  19. Flexible and rigid cystoscopy in women.

    PubMed

    Gee, Jason R; Waterman, Bradley J; Jarrard, David F; Hedican, Sean P; Bruskewitz, Reginald C; Nakada, Stephen Y

    2009-01-01

    Previous studies have evaluated the tolerability of rigid versus flexible cystoscopy in men. Similar studies, however, have not been performed in women. We sought to determine whether office-based flexible cystoscopy was better tolerated than rigid cystoscopy in women. Following full IRB approval, women were prospectively randomized in a single-blind manner. Patients were randomized to flexible or rigid cystoscopy and draped in the lithotomy position to maintain blinding of the study. Questionnaires evaluated discomfort before, during, and after cystoscopy. Thirty-six women were randomized to flexible (18) or rigid (18) cystoscopy. Indications were surveillance (16), hematuria (15), recurrent UTIs (2), voiding dysfunction (1), and other (2). All questionnaires were returned by 31/36 women. Using a 10-point visual analog scale (VAS), median discomfort during the procedure for flexible and rigid cystoscopy were 1.4 and 1.8, respectively, in patients perceiving pain. Median recalled pain 1 week later was similar at 0.8 and 1.15, respectively. None of these differences were statistically significant. Flexible and rigid cystoscopy are well tolerated in women. Discomfort during and after the procedure is minimal in both groups. Urologists should perform either procedure in women based on their preference and skill level.

  20. Origami Metamaterial based on Pattern Rigidity

    NASA Astrophysics Data System (ADS)

    Chen, Yan; You, Zhong

    Origami inspired mechanical metamaterials are made from a tessellation of origami units. Their mechanical behaviour is closely related to the behaviour of the origami units used. In this article, we focus on a family of metamaterials that are created by the tessellation of the square twist origami units. Generally a square twist origami unit can have four distinct hill-valley crease arrangements, two of which are rigidly foldable whereas the others are not. The rigidly foldable unit has, in general, lower stiffness than that of the non-rigidly foldable one if the facets can easily rotate about the creases. We shall show that it is possible to put rigidly foldable and non-rigidly foldable units together to form a geometrically compatible tessellation, and the stiffness of the overall structure based on such a tessellation is primarily decided by the number of non-rigid units. By astutely placing such units in a tessellation, we are able to create a metamaterial with a tunable stiffness. Y Chen acknowledges the support of the NSFC (Projects 51290293 and 51422506) and the Ministry of Science and Technology of China (Project 2014DFA70710). Z You wishes to acknowledge the support of Air Force Office of Scientific Research (FA9550-16-1-0339).

  1. Electrically conductive rigid polyurethane foam

    DOEpatents

    Neet, Thomas E.; Spieker, David A.

    1985-03-19

    A rigid, polyurethane foam comprises about 2-10 weight percent, based on the total foam weight, of a carbon black which is CONDUCTEX CC-40-220 or CONDUCTEX SC, whereby the rigid polyurethane foam is electrically conductive and has essentially the same mechanical properties as the same foam without carbon black added.

  2. Electrically conductive rigid polyurethane foam

    DOEpatents

    Neet, T.E.; Spieker, D.A.

    1983-12-08

    A rigid, moldable polyurethane foam comprises about 2 to 10 weight percent, based on the total foam weight, of a carbon black which is CONDUCTEX CC-40-220 or CONDUCTEX SC, whereby the rigid polyurethane foam is electrically conductive and has essentially the same mechanical properties as the same foam without carbon black added.

  3. Non-rigid, but not rigid, motion interferes with the processing of structural face information in developmental prosopagnosia.

    PubMed

    Maguinness, Corrina; Newell, Fiona N

    2015-04-01

    There is growing evidence to suggest that facial motion is an important cue for face recognition. However, it is poorly understood whether motion is integrated with facial form information or whether it provides an independent cue to identity. To provide further insight into this issue, we compared the effect of motion on face perception in two developmental prosopagnosics and age-matched controls. Participants first learned faces presented dynamically (video), or in a sequence of static images, in which rigid (viewpoint) or non-rigid (expression) changes occurred. Immediately following learning, participants were required to match a static face image to the learned face. Test face images varied by viewpoint (Experiment 1) or expression (Experiment 2) and were learned or novel face images. We found similar performance across prosopagnosics and controls in matching facial identity across changes in viewpoint when the learned face was shown moving in a rigid manner. However, non-rigid motion interfered with face matching across changes in expression in both individuals with prosopagnosia compared to the performance of control participants. In contrast, non-rigid motion did not differentially affect the matching of facial expressions across changes in identity for either prosopagnosics (Experiment 3). Our results suggest that whilst the processing of rigid motion information of a face may be preserved in developmental prosopagnosia, non-rigid motion can specifically interfere with the representation of structural face information. Taken together, these results suggest that both form and motion cues are important in face perception and that these cues are likely integrated in the representation of facial identity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Rigid versus semi-rigid orthotic use following TMC arthroplasty: a randomized controlled trial.

    PubMed

    Prosser, Rosemary; Hancock, Mark J; Nicholson, Leslie; Merry, Cathy; Thorley, Felicity; Wheen, Douglass

    2014-01-01

    The trapeziometacarpal (TMC) joint of the human thumb is the second most common joint in the hand affected by osteoarthritis. TMC arthroplasty is a common procedure used to alleviate symptoms. No randomized controlled trials have been published on the efficacy of different post-operative orthotic regimes. Fifty six participants who underwent TMC arthroplasty were allocated to either rigid orthotic or semi-rigid orthotic groups. Both groups started an identical exercise program at two weeks following surgery. Outcome measures were assessed by an assessor blinded to group allocation. The primary outcome was the Patient Rated Wrist and Hand Evaluation (PRWHE) and secondary outcomes included the Michigan Hand Questionnaire (MHQ), thumb palmar abduction, first metacarpophalangeal extension and three point pinch grip. Measures were taken pre-operatively, at six weeks, three months and one year post-operatively. Between-group differences were analyzed with linear regression. Both groups performed equally well. There was no significant between-group difference for PRWHE scores (0.47, CI -11.5 to 12.4), including subscales for pain and function, or for any of the secondary outcomes at one year follow-up. We found no difference in outcomes between using a rigid or semi-rigid orthosis after TMC arthroplasty. Patient comfort, cost and availability may determine choice between orthoses in clinical practice. 1b RCT. Copyright © 2014 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

  5. Electrostatic contribution to twist rigidity of DNA.

    PubMed

    Mohammad-Rafiee, Farshid; Golestanian, Ramin

    2004-06-01

    The electrostatic contribution to the twist rigidity of DNA is studied, and it is shown that the Coulomb self-energy of the double-helical sugar-phosphate backbone makes a considerable contribution-the electrostatic twist rigidity of DNA is found to be C(elec) approximately 5 nm, which makes up about 7% of its total twist rigidity ( C(DNA) approximately 75 nm). The electrostatic twist rigidity is found, however, to depend only weakly on the salt concentration, because of a competition between two different screening mechanisms: (1) Debye screening by the salt ions in the bulk, and (2) structural screening by the periodic charge distribution along the backbone of the helical polyelectrolyte. It is found that, depending on the parameters, the electrostatic contribution to the twist rigidity could stabilize or destabilize the structure of a helical polyelectrolyte.

  6. Shear-induced migration and orientation of rigid fibers

    NASA Astrophysics Data System (ADS)

    Butler, Jason; Strednak, Scott; Shaikh, Saif; Guazzelli, Elisabeth

    2017-11-01

    The spatial and orientation distributions are measured for a suspension of fibers during pressure-driven flow. The fibers are rigid and non-colloidal, and two aspect ratios (length to diameter ratios) of 12 and 24 were tested; the suspending fluid is viscous, Newtonian, and density matched to the particles. As with the migration of spheres in parabolic flows, the fibers migrate toward the centerline of the channel if the concentration is sufficiently high. Migration is not observed for concentrations below a volume fraction of 0.035 for aspect ratio 24 and 0.07 for aspect ratio 12. The orientation distribution of the fibers is spatially dependent. Fibers near the center of the channel align closely with the flow direction, but fibers near the wall are observed to preferentially align in the vorticity (perpendicular to the flow and gradient) direction. National Science Foundation (Grants #1511787 and #1362060).

  7. Non-rigid Earth rotation series

    NASA Astrophysics Data System (ADS)

    Pashkevich, V. V.

    2008-04-01

    The last years a lot of attempts to derive a high-precision theory of the non-rigid Earth rotation was carried out. For these purposes the different transfer functions are used. Usually these transfer func- tions are applied to the series representing the nutation in longitude and in obliquity of the rigid Earth rotation with respect to the ecliptic of date. The aim of this investigation is a construction of the new high- precision non-rigid Earth rotation series (SN9000), dynamically adequate to the DE404/LE404 ephemeris over 2000 years, which are expressed as a function of Euler angles ψ, θ and φ with respect to the fixed ecliptic plane and equinox J2000.0. The early stages of the previous investigation: 1. The high-precision numerical solution of the rigid Earth rotation have been constructed (V.V.Pashkevich, G.I.Eroshkin and A.Brzezinski, 2004), (V.V.Pashkevich and G.I.Eroshkin, Proceedings of Journees 2004). The initial con- ditions have been calculated from SMART97 (P.Bretagnon, G.Francou, P.Rocher, J.L.Simon,1998). The discrepancies between the numerical solution and the semi-analytical solution SMART97 were obtained in Euler angles over 2000 years with one-day spacing. 2. Investigation of the discrepancies is carried out by the least squares and by the spectral analysis algorithms (V.V.Pashkevich and G.I.Eroshkin, Proceedings of Journees 2005). The high-precision rigid Earth rotation series S9000 are determined (V.V.Pashkevich and G.I.Eroshkin, 2005 ). The next stage of this investigation: 3. The new high-precision non-rigid Earth rotation series (SN9000), which are expressed as a function of Euler angles, are constructed by using the method (P.Bretagnon, P.M.Mathews, J.-L.Simon: 1999) and the transfer function MHB2002 (Mathews, P. M., Herring, T. A., and Buffett B. A., 2002).

  8. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Standards for rigid plastic IBCs. 178.706 Section... Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types are...

  9. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Standards for rigid plastic IBCs. 178.706 Section... Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types are...

  10. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Standards for rigid plastic IBCs. 178.706 Section... Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types are...

  11. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Standards for rigid plastic IBCs. 178.706 Section... Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types are...

  12. Identifying Floppy and Rigid Regions in Proteins

    NASA Astrophysics Data System (ADS)

    Jacobs, D. J.; Thorpe, M. F.; Kuhn, L. A.

    1998-03-01

    In proteins it is possible to separate hard covalent forces involving bond lengths and bond angles from other weak forces. We model the microstructure of the protein as a generic bar-joint truss framework, where the hard covalent forces and strong hydrogen bonds are regarded as rigid bar constraints. We study the mechanical stability of proteins using FIRST (Floppy Inclusions and Rigid Substructure Topography) based on a recently developed combinatorial constraint counting algorithm (the 3D Pebble Game), which is a generalization of the 2D pebble game (D. J. Jacobs and M. F. Thorpe, ``Generic Rigidity: The Pebble Game'', Phys. Rev. Lett.) 75, 4051-4054 (1995) for the special class of bond-bending networks (D. J. Jacobs, "Generic Rigidity in Three Dimensional Bond-bending Networks", Preprint Aug (1997)). This approach is useful in identifying rigid motifs and flexible linkages in proteins, and thereby determines the essential degrees of freedom. We will show some preliminary results from the FIRST analysis on the myohemerythrin and lyozyme proteins.

  13. Rigid-Rod Polyimides

    NASA Technical Reports Server (NTRS)

    Chuang, Kathy C.; Kinder, James D.; Hull, Diana L.; Youngs, Wiley J.

    1996-01-01

    Experimental polyimides relatively rigid synthesized in effort to exploit some of advantages of rodlike polymers, while alleviating disadvantages. Polymers used to make colorless fibers and transparent films for optical and electronic application.

  14. 21 CFR 882.1020 - Rigidity analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rigidity analyzer. 882.1020 Section 882.1020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1020 Rigidity analyzer. (a...

  15. 21 CFR 882.1020 - Rigidity analyzer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigidity analyzer. 882.1020 Section 882.1020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1020 Rigidity analyzer. (a...

  16. Rigidity and retention of root canal posts.

    PubMed

    Purton, D G; Chandler, N P; Love, R M

    1998-03-28

    To test the rigidity and the retention into roots of parallel root canal posts, one a spiral vented titanium post and the other a spiral serrated, hollow, stainless steel post. A serrated, stainless steel post was used as the control. A three-point bending test was used to test rigidity. To test retention, ten posts of each type were cemented into the roots of extracted teeth with a resin cement and the tensile loads required to remove them were compared using Student's t and Mann-Whitney U tests. The serrated stainless steel posts were significantly more rigid than either of the other types. The titanium posts and the stainless steel hollow posts were not significantly different in rigidity. The serrated, stainless steel posts were significantly better retained than either of the other types. The titanium posts showed greater retention than the hollow posts. Within the limits of the study the stainless steel, serrated posts were superior to the two newer types in terms of rigidity and retention into roots.

  17. 21 CFR 874.4680 - Bronchoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... such as stainless steel or flexible plastic. This generic type of device includes the rigid ventilating... foreign body claw, bronchoscope tubing, flexible biopsy forceps, rigid biopsy curette, flexible biopsy brush, rigid biopsy forceps, flexible biopsy curette, and rigid bronchoscope aspirating tube, but...

  18. Advanced Rigid Ablative TPS

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew J.

    2011-01-01

    NASA Exploration Systems Mission Directorate s (ESMD) Entry, Descent, and Landing (EDL) Technology Development Project (TDP) and the NASA Aeronautics Research Mission Directorate s (ARMD) Hypersonics Project are developing new advanced rigid ablators in an effort to substantially increase reliability, decrease mass, and reduce life cycle cost of rigid aeroshell-based entry systems for multiple missions. Advanced Rigid Ablators combine ablation resistant top layers capable of high heat flux entry and enable high-speed EDL with insulating mass-efficient bottom that, insulate the structure and lower the areal weight. These materials may benefit Commercial Orbital Transportation Services (COTS) vendors and may potentially enable new NASA missions for higher velocity returns (e.g. asteroid, Mars). The materials have been thermally tested to 400-450 W/sq cm at the Laser Hardened Materials Evaluation Lab (LHMEL), Hypersonics Materials Evaluation Test System (HyMETS) and in arcjet facilities. Tested materials exhibit much lower backface temperatures and reduced recession over the baseline materials (PICA). Although the EDL project is ending in FY11, NASA in-house development of advanced ablators will continue with a focus on varying resin systems and fiber/resin interactions.

  19. Method of preparing porous, rigid ceramic separators for an electrochemical cell

    DOEpatents

    Bandyopadhyay, Gautam; Dusek, Joseph T.

    1981-01-01

    Porous, rigid separators for electrochemical cells are prepared by first calcining particles of ceramic material at temperatures above about 1200.degree. C. for a sufficient period of time to reduce the sinterability of the particles. A ceramic powder that has not been calcined is blended with the original powder to control the porosity of the completed separator. The ceramic blend is then pressed into a sheet of the desired shape and sintered at a temperature somewhat lower than the calcination temperature. Separator sheets of about 1 to 2.5 mm thickness and 30 to 70% porosity can be prepared by this technique. Ceramics such as yttria, magnesium oxide and magnesium-aluminum oxide have advantageously been used to form separators by this method.

  20. Perceptual, Cognitive, and Personality Rigidity in Parkinson’s Disease

    PubMed Central

    Díaz-Santos, Mirella; Cao, Bo; Yazdanbakhsh, Arash; Norton, Daniel J.; Neargarder, Sandy; Cronin-Golomb, Alice

    2015-01-01

    Parkinson’s disease (PD) is associated with motor and non-motor rigidity symptoms (e.g., cognitive and personality). The question is raised as to whether rigidity in PD also extends to perception, and if so, whether perceptual, cognitive, and personality rigidities are correlated. Bistable stimuli were presented to 28 non-demented individuals with PD and 26 normal control adults (NC). Necker cube perception and binocular rivalry were examined during passive viewing, and the Necker cube was additionally used for two volitional-control conditions: Hold one percept in front, and Switch between the two percepts. Relative to passive viewing, PD were significantly less able than NC to reduce dominance durations in the Switch condition, indicating perceptual rigidity. Tests of cognitive flexibility and a personality questionnaire were administered to explore the association with perceptual rigidity. Cognitive flexibility was not correlated with perceptual rigidity for either group. Personality (novelty seeking) correlated with dominance durations on Necker passive viewing for PD but not NC. The results indicate the presence in mild-moderate PD of perceptual rigidity and suggest shared neural substrates with novelty seeking, but functional divergence from those supporting cognitive flexibility. The possibility is raised that perceptual rigidity may be a harbinger of cognitive inflexibility later in the disease course. PMID:25640973

  1. The Rigid Orthogonal Procrustes Rotation Problem

    ERIC Educational Resources Information Center

    ten Berge, Jos M. F.

    2006-01-01

    The problem of rotating a matrix orthogonally to a best least squares fit with another matrix of the same order has a closed-form solution based on a singular value decomposition. The optimal rotation matrix is not necessarily rigid, but may also involve a reflection. In some applications, only rigid rotations are permitted. Gower (1976) has…

  2. Rigid shells enhance survival of gekkotan eggs.

    PubMed

    Andrews, Robin M

    2015-11-01

    The majority of lizards and snakes produce permeable parchment-shelled eggs that require high moisture conditions for successful embryonic development. One clade of gekkotan lizards is an exception; females produce relatively impermeable rigid-shelled eggs that normally incubate successfully under low moisture conditions. I tested the hypothesis that the rigid-shell increases egg survival during incubation, but only under low moisture conditions. To test this hypothesis, I incubated rigid-shelled eggs of Chondrodactylus turneri under low and under high moisture conditions. Eggs were incubated with parchment-shelled eggs of Eublepharis macularius to insure that incubation conditions were suitable for parchment-shelled eggs. Chondrodactylus turneri eggs had very high survival (>90%) when they were incubated under low moisture conditions. In contrast, eggs incubated under high moisture conditions had low survival overall, and lower survival than those of the parchment-shelled eggs of E. macularius. Mortality of C. turneri and E. macularius eggs incubated under high moisture conditions was the result of fungal infection, a common source of egg mortality for squamates under laboratory and field conditions. These observations document high survival of rigid-shelled eggs under low moisture conditions because eggs escape from fungal infection. Highly mineralized rigid shells also make egg survival independent of moisture availability and may also provide protection from small invertebrates in nature. Enhanced egg survival could thus compensate for the low reproductive output of gekkotans that produce rigid-shelled eggs. © 2015 Wiley Periodicals, Inc.

  3. Rigidity controllable polishing tool based on magnetorheological effect

    NASA Astrophysics Data System (ADS)

    Wang, Jia; Wan, Yongjian; Shi, Chunyan

    2012-10-01

    A stable and predictable material removal function (MRF) plays a crucial role in computer controlled optical surfacing (CCOS). For physical contact polishing case, the stability of MRF depends on intimate contact between polishing interface and workpiece. Rigid laps maintain this function in polishing spherical surfaces, whose curvature has no variation with the position on the surface. Such rigid laps provide smoothing effect for mid-spatial frequency errors, but can't be used in aspherical surfaces for they will destroy the surface figure. Flexible tools such as magnetorheological fluid or air bonnet conform to the surface [1]. They lack rigidity and provide little natural smoothing effect. We present a rigidity controllable polishing tool that uses a kind of magnetorheological elastomers (MRE) medium [2]. It provides the ability of both conforming to the aspheric surface and maintaining natural smoothing effect. What's more, its rigidity can be controlled by the magnetic field. This paper will present the design, analysis, and stiffness variation mechanism model of such polishing tool [3].

  4. 21 CFR 874.4680 - Bronchoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... foreign body claw, bronchoscope tubing, flexible biopsy forceps, rigid biopsy curette, flexible biopsy brush, rigid biopsy forceps, flexible biopsy curette, and rigid bronchoscope aspirating tube, but...

  5. 21 CFR 874.4680 - Bronchoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... foreign body claw, bronchoscope tubing, flexible biopsy forceps, rigid biopsy curette, flexible biopsy brush, rigid biopsy forceps, flexible biopsy curette, and rigid bronchoscope aspirating tube, but...

  6. 21 CFR 874.4680 - Bronchoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... foreign body claw, bronchoscope tubing, flexible biopsy forceps, rigid biopsy curette, flexible biopsy brush, rigid biopsy forceps, flexible biopsy curette, and rigid bronchoscope aspirating tube, but...

  7. Thermostability in rubredoxin and its relationship to mechanical rigidity

    NASA Astrophysics Data System (ADS)

    Rader, A. J.

    2010-03-01

    The source of increased stability in proteins from organisms that thrive in extreme thermal environments is not well understood. Previous experimental and theoretical studies have suggested many different features possibly responsible for such thermostability. Many of these thermostabilizing mechanisms can be accounted for in terms of structural rigidity. Thus a plausible hypothesis accounting for this remarkable stability in thermophilic enzymes states that these enzymes have enhanced conformational rigidity at temperatures below their native, functioning temperature. Experimental evidence exists to both support and contradict this supposition. We computationally investigate the relationship between thermostability and rigidity using rubredoxin as a case study. The mechanical rigidity is calculated using atomic models of homologous rubredoxin structures from the hyperthermophile Pyrococcus furiosus and mesophile Clostridium pasteurianum using the FIRST software. A global increase in structural rigidity (equivalently a decrease in flexibility) corresponds to an increase in thermostability. Locally, rigidity differences (between mesophilic and thermophilic structures) agree with differences in protection factors.

  8. Minimal energy configurations of gravitationally interacting rigid bodies

    NASA Astrophysics Data System (ADS)

    Moeckel, Richard

    2017-05-01

    Consider a collection of n rigid, massive bodies interacting according to their mutual gravitational attraction. A relative equilibrium motion is one where the entire configuration rotates rigidly and uniformly about a fixed axis in R^3. Such a motion is possible only for special positions and orientations of the bodies. A minimal energy motion is one which has the minimum possible energy in its fixed angular momentum level. While every minimal energy motion is a relative equilibrium motion, the main result here is that a relative equilibrium motion of n≥3 disjoint rigid bodies is never an energy minimizer. This generalizes a known result about point masses to the case of rigid bodies.

  9. 49 CFR 587.18 - Dimensions of fixed rigid barrier.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) DEFORMABLE BARRIERS Offset Deformable Barrier § 587.18 Dimensions of fixed rigid barrier. (a) The fixed rigid barrier has a mass of not... 49 Transportation 7 2010-10-01 2010-10-01 false Dimensions of fixed rigid barrier. 587.18 Section...

  10. 49 CFR 587.18 - Dimensions of fixed rigid barrier.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 7 2011-10-01 2011-10-01 false Dimensions of fixed rigid barrier. 587.18 Section 587.18 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL HIGHWAY... Deformable Barrier § 587.18 Dimensions of fixed rigid barrier. (a) The fixed rigid barrier has a mass of not...

  11. 49 CFR 587.18 - Dimensions of fixed rigid barrier.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 7 2012-10-01 2012-10-01 false Dimensions of fixed rigid barrier. 587.18 Section 587.18 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL HIGHWAY... Deformable Barrier § 587.18 Dimensions of fixed rigid barrier. (a) The fixed rigid barrier has a mass of not...

  12. 49 CFR 587.18 - Dimensions of fixed rigid barrier.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 7 2014-10-01 2014-10-01 false Dimensions of fixed rigid barrier. 587.18 Section 587.18 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL HIGHWAY... Deformable Barrier § 587.18 Dimensions of fixed rigid barrier. (a) The fixed rigid barrier has a mass of not...

  13. 49 CFR 587.18 - Dimensions of fixed rigid barrier.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 7 2013-10-01 2013-10-01 false Dimensions of fixed rigid barrier. 587.18 Section 587.18 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL HIGHWAY... Deformable Barrier § 587.18 Dimensions of fixed rigid barrier. (a) The fixed rigid barrier has a mass of not...

  14. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens. 886.5916 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5916 Rigid gas permeable contact lens. (a) Identification. A rigid gas permeable contact lens is a device intended to be worn directly...

  15. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rigid gas permeable contact lens. 886.5916 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5916 Rigid gas permeable contact lens. (a) Identification. A rigid gas permeable contact lens is a device intended to be worn directly...

  16. Flex-rigid pleuroscopic biopsy with the SB knife Jr is a novel technique for diagnosis of malignant or benign fibrothorax.

    PubMed

    Wang, Xiao-Bo; Yin, Yan; Miao, Yuan; Eberhardt, Ralf; Hou, Gang; Herth, Felix J; Kang, Jian

    2016-11-01

    Diagnosing pleural effusion is challenging, especially in patients with malignant or benign fibrothorax, which is difficult to sample using standard flexible forceps (SFF) via flex-rigid pleuroscopy. An adequate sample is crucial for the differential diagnosis of malignant fibrothorax (malignant pleural mesothelioma, metastatic lung carcinoma, etc.) from benign fibrothorax (benign asbestos pleural disease, tuberculous pleuritis, etc.). Novel biopsy techniques are required in flex-rigid pleuroscopy to improve the sample size and quality. The SB knife Jr, which is a scissor forceps that uses a mono-pole high frequency, was developed to allow convenient and accurate resection of larger lesions during endoscopic dissection (ESD). Herein, we report two patients with fibrothorax who underwent a pleural biopsy using an SB knife Jr to investigate the potential use of this tool in flex-rigid pleuroscopy when pleural lesions are difficult to biopsy via SFF. The biopsies were successful, with sufficient size and quality for definitive diagnosis. We also successfully performed adhesiolysis with the SB knife Jr in one case, and adequate biopsies were conducted. No complications were observed. Electrosurgical biopsy with the SB knife Jr during flex-rigid pleuroscopy allowed us to obtain adequate samples for the diagnosis of malignant versus benign fibrothorax, which is usually not possible with SFF. The SB knife Jr also demonstrated a potential use for pleuropulmonary adhesions.

  17. A theoretical evaluation of rigid baffles in suppression of combustion instability

    NASA Technical Reports Server (NTRS)

    Baer, M. R.; Mitchell, C. E.

    1976-01-01

    An analytical technique for the prediction of the effects of rigid baffles on the stability of liquid propellant combustors is presented. A three dimensional combustor model characterized by a concentrated combustion source at the chamber injector and a constant Mach number nozzle is used. The linearized partial differential equations describing the unsteady flow field are solved by an eigenfunction matching method. Boundary layer corrections to this unsteady flow are used to evaluate viscous and turbulence effects within the flow. An integral stability relationship is then employed to predict the decay rate of the oscillations. Results show that sufficient dissipation exists to indicate that the proper mechanism of baffle damping is a fluid dynamic loss. The response of the dissipation model to varying baffle blade length, mean flow Mach number and oscillation amplitude is examined.

  18. 21 CFR 876.3630 - Penile rigidity implant.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Penile rigidity implant. 876.3630 Section 876.3630 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Prosthetic Devices § 876.3630 Penile rigidity implant. (a...

  19. Reversible Rigidity Control Using Low Melting Temperature Alloys

    NASA Astrophysics Data System (ADS)

    Shan, Wanliang; Lu, Tong; Majidi, Carmel

    2013-03-01

    Inspired by nature, materials able to achieve rapid rigidity changes have important applications for human body protection in military and many other areas. This talk presents the fabrication and design of soft-matter technologies that exhibit rapid reversible rigidity control. Fabricated with a masked deposition technique, the soft-matter composite contains liquid-phase and phase-changing metal alloys embedded in a soft and highly stretchable elastomer. The composite material can reversibly change its rigidity by three orders of magnitude and sustain large deformation.

  20. IFACEwat: the interfacial water-implemented re-ranking algorithm to improve the discrimination of near native structures for protein rigid docking.

    PubMed

    Su, Chinh; Nguyen, Thuy-Diem; Zheng, Jie; Kwoh, Chee-Keong

    2014-01-01

    Protein-protein docking is an in silico method to predict the formation of protein complexes. Due to limited computational resources, the protein-protein docking approach has been developed under the assumption of rigid docking, in which one of the two protein partners remains rigid during the protein associations and water contribution is ignored or implicitly presented. Despite obtaining a number of acceptable complex predictions, it seems to-date that most initial rigid docking algorithms still find it difficult or even fail to discriminate successfully the correct predictions from the other incorrect or false positive ones. To improve the rigid docking results, re-ranking is one of the effective methods that help re-locate the correct predictions in top high ranks, discriminating them from the other incorrect ones. Our results showed that the IFACEwat increased both the numbers of the near-native structures and improved their ranks as compared to the initial rigid docking ZDOCK3.0.2. In fact, the IFACEwat achieved a success rate of 83.8% for Antigen/Antibody complexes, which is 10% better than ZDOCK3.0.2. As compared to another re-ranking technique ZRANK, the IFACEwat obtains success rates of 92.3% (8% better) and 90% (5% better) respectively for medium and difficult cases. When comparing with the latest published re-ranking method F2Dock, the IFACEwat performed equivalently well or even better for several Antigen/Antibody complexes. With the inclusion of interfacial water, the IFACEwat improves mostly results of the initial rigid docking, especially for Antigen/Antibody complexes. The improvement is achieved by explicitly taking into account the contribution of water during the protein interactions, which was ignored or not fully presented by the initial rigid docking and other re-ranking techniques. In addition, the IFACEwat maintains sufficient computational efficiency of the initial docking algorithm, yet improves the ranks as well as the number of the near

  1. Rigid fixation of facial fractures in children.

    PubMed

    Koltai, P J; Rabkin, D; Hoehn, J

    1995-01-01

    This article presents a retrospective analysis of a selective use of rigid fixation among 62 children with facial fractures, treated at a Level I trauma center over a 5-year period (1986-1991). There were 21 mandible fractures, 11 orbital fractures, 11 zygomaticomalar complex fractures, 7 nasal fractures, 5 maxillary fractures, 3 pan-facial fractures, 2 nasal-orbital-ethmoidal complex fractures, and 2 frontal sinus fractures. Only 18 children had rigid fixation of their injuries. Complications of Le Fort upper facial fractures repaired with rigid fixation involved perioperative sinusitis; one case required oral antibiotics, the other ethmoidectomy and maxillary antrostomy. One child with a Le Fort fracture had delayed exposure of a zygomaticomalar buttress plate, which required surgical removal. Permanent enophthalmos occurred in two children with Le Fort fractures. The authors conclude that traditional conservative management is appropriate in most cases. However, in children aged 13 and older with mandible fractures and children with complex mid- and upper facial fractures, a judicious use of rigid fixation has advantages over the traditional techniques.

  2. Endoscope shaft-rigidity control mechanism: "FORGUIDE".

    PubMed

    Loeve, Arjo J; Plettenburg, Dick H; Breedveld, Paul; Dankelman, Jenny

    2012-02-01

    Recent developments in flexible endoscopy and other fields of medical technology have raised the need for compact slender shafts that can be made rigid and compliant at will. A novel compact mechanism, named FORGUIDE, with this functionality was developed. The FORGUIDE shaft rigidifies due to friction between a ring of cables situated between a spring and an inflated tube. A mathematical model for the FORGUIDE mechanism working principle was made and used to obtain understanding of this mechanism, predict the maximum rigidity of a FORGUIDE shaft design, and tune its design variables. The mathematical model gave suggestions for significant performance improvement by fine-tuning the design. A prototype FORGUIDE shaft was built and put to a series of bench tests. These tests showed that the FORGUIDE mechanism provides a reliable and simple way to control the rigidity of a flexible shaft. © 2011 IEEE

  3. Soft-matter composites with electrically tunable elastic rigidity

    NASA Astrophysics Data System (ADS)

    Shan, Wanliang; Lu, Tong; Majidi, Carmel

    2013-08-01

    We use a phase-changing metal alloy to reversibly tune the elastic rigidity of an elastomer composite. The elastomer is embedded with a sheet of low-melting-point Field’s metal and an electric Joule heater composed of a serpentine channel of liquid-phase gallium-indium-tin (Galinstan®) alloy. At room temperature, the embedded Field’s metal is solid and the composite remains elastically rigid. Joule heating causes the Field’s metal to melt and allows the surrounding elastomer to freely stretch and bend. Using a tensile testing machine, we measure that the effective elastic modulus of the composite reversibly changes by four orders of magnitude when powered on and off. This dramatic change in rigidity is accurately predicted with a model for an elastic composite. Reversible rigidity control is also accomplished by replacing the Field’s metal with shape memory polymer. In addition to demonstrating electrically tunable rigidity with an elastomer, we also introduce a new technique to rapidly produce soft-matter electronics and multifunctional materials in several minutes with laser-patterned adhesive film and masked deposition of liquid-phase metal alloy.

  4. Analysis and optimization of the active rigidity joint

    NASA Astrophysics Data System (ADS)

    Manzo, Justin; Garcia, Ephrahim

    2009-12-01

    The active rigidity joint is a composite mechanism using shape memory alloy and shape memory polymer to create a passively rigid joint with thermally activated deflection. A new model for the active rigidity joint relaxes constraints of earlier methods and allows for more accurate deflection predictions compared to finite element results. Using an iterative process to determine the strain distribution and deflection, the method demonstrates accurate results for both surface bonded and embedded actuators with and without external loading. Deflection capabilities are explored through simulated annealing heuristic optimization using a variety of cost functions to explore actuator performance. A family of responses presents actuator characteristics in terms of load bearing and deflection capabilities given material and thermal constraints. Optimization greatly expands the available workspace of the active rigidity joint from the initial configuration, demonstrating specific work capabilities comparable to those of muscle tissue.

  5. Contribution of Jules Froment to the study of parkinsonian rigidity.

    PubMed

    Broussolle, Emmanuel; Krack, Paul; Thobois, Stéphane; Xie-Brustolin, Jing; Pollak, Pierre; Goetz, Christopher G

    2007-05-15

    Rigidity is commonly defined as a resistance to passive movement. In Parkinson's disease (PD), two types of rigidity are classically recognized which may coexist, "leadpipe " and "cogwheel". Charcot was the first to investigate parkinsonian rigidity during the second half of the nineteenth century, whereas Negro and Moyer described cogwheel rigidity at the beginning of the twentieth century. Jules Froment, a French neurologist from Lyon, contributed to the study of parkinsonian rigidity during the 1920s. He investigated rigidity of the wrist at rest in a sitting position as well as in stable and unstable standing postures, both clinically and with physiological recordings using a myograph. With Gardère, Froment described enhanced resistance to passive movements of a limb about a joint that can be detected specifically when there is a voluntary action of another contralateral body part. This has been designated in the literature as the "Froment's maneuver " and the activation or facilitation test. In addition, Froment showed that parkinsonian rigidity diminishes, vanishes, or enhances depending on the static posture of the body. He proposed that in PD "maintenance stabilization " of the body is impaired and that "reactive stabilization " becomes the operative mode of muscular tone control. He considered "rigidification " as compensatory against the forces of gravity. Froment also demonstrated that parkinsonian rigidity increases during the Romberg test, gaze deviation, and oriented attention. In their number, breadth, and originality, Froment's contributions to the study of parkinsonian rigidity remain currently relevant to clinical and neurophysiological issues of PD. (c) 2007 Movement Disorder Society.

  6. Digital Correction of Motion Artifacts in Microscopy Image Sequences Collected from Living Animals Using Rigid and Non-Rigid Registration

    PubMed Central

    Lorenz, Kevin S.; Salama, Paul; Dunn, Kenneth W.; Delp, Edward J.

    2013-01-01

    Digital image analysis is a fundamental component of quantitative microscopy. However, intravital microscopy presents many challenges for digital image analysis. In general, microscopy volumes are inherently anisotropic, suffer from decreasing contrast with tissue depth, lack object edge detail, and characteristically have low signal levels. Intravital microscopy introduces the additional problem of motion artifacts, resulting from respiratory motion and heartbeat from specimens imaged in vivo. This paper describes an image registration technique for use with sequences of intravital microscopy images collected in time-series or in 3D volumes. Our registration method involves both rigid and non-rigid components. The rigid registration component corrects global image translations, while the non-rigid component manipulates a uniform grid of control points defined by B-splines. Each control point is optimized by minimizing a cost function consisting of two parts: a term to define image similarity, and a term to ensure deformation grid smoothness. Experimental results indicate that this approach is promising based on the analysis of several image volumes collected from the kidney, lung, and salivary gland of living rodents. PMID:22092443

  7. Sensing of substratum rigidity and directional migration by fast-crawling cells

    NASA Astrophysics Data System (ADS)

    Okimura, Chika; Sakumura, Yuichi; Shimabukuro, Katsuya; Iwadate, Yoshiaki

    2018-05-01

    Living cells sense the mechanical properties of their surrounding environment and respond accordingly. Crawling cells detect the rigidity of their substratum and migrate in certain directions. They can be classified into two categories: slow-moving and fast-moving cell types. Slow-moving cell types, such as fibroblasts, smooth muscle cells, mesenchymal stem cells, etc., move toward rigid areas on the substratum in response to a rigidity gradient. However, there is not much information on rigidity sensing in fast-moving cell types whose size is ˜10 μ m and migration velocity is ˜10 μ m /min . In this study, we used both isotropic substrata with different rigidities and an anisotropic substratum that is rigid on the x axis but soft on the y axis to demonstrate rigidity sensing by fast-moving Dictyostelium cells and neutrophil-like differentiated HL-60 cells. Dictyostelium cells exerted larger traction forces on a more rigid isotropic substratum. Dictyostelium cells and HL-60 cells migrated in the "soft" direction on the anisotropic substratum, although myosin II-null Dictyostelium cells migrated in random directions, indicating that rigidity sensing of fast-moving cell types differs from that of slow types and is induced by a myosin II-related process.

  8. Sensing of substratum rigidity and directional migration by fast-crawling cells.

    PubMed

    Okimura, Chika; Sakumura, Yuichi; Shimabukuro, Katsuya; Iwadate, Yoshiaki

    2018-05-01

    Living cells sense the mechanical properties of their surrounding environment and respond accordingly. Crawling cells detect the rigidity of their substratum and migrate in certain directions. They can be classified into two categories: slow-moving and fast-moving cell types. Slow-moving cell types, such as fibroblasts, smooth muscle cells, mesenchymal stem cells, etc., move toward rigid areas on the substratum in response to a rigidity gradient. However, there is not much information on rigidity sensing in fast-moving cell types whose size is ∼10 μm and migration velocity is ∼10 μm/min. In this study, we used both isotropic substrata with different rigidities and an anisotropic substratum that is rigid on the x axis but soft on the y axis to demonstrate rigidity sensing by fast-moving Dictyostelium cells and neutrophil-like differentiated HL-60 cells. Dictyostelium cells exerted larger traction forces on a more rigid isotropic substratum. Dictyostelium cells and HL-60 cells migrated in the "soft" direction on the anisotropic substratum, although myosin II-null Dictyostelium cells migrated in random directions, indicating that rigidity sensing of fast-moving cell types differs from that of slow types and is induced by a myosin II-related process.

  9. Balancing of Rigid and Flexible Rotors

    DTIC Science & Technology

    1986-01-01

    and Vibration Information Center at NRL and Dr. J. Gordan Showalter, the acting director for their supportive recognition of the importance of this...RIGID AND FLEXIBLE ROTORS Comparizon of Exact-Poriqt.SpWed and Least-Squareq Influence Coefficient ýIalncin8 The least-squares procedure differs from the...that the critical speeds are still to be iI2 486 BALANCING OF RIGID AND FLEXIBLE ROTORS 101 too .10 l0-* -Stat~llon- STATION 2 0 2000 0000 600 logo

  10. 49 CFR 178.925 - Standards for rigid plastic Large Packagings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Standards for rigid plastic Large Packagings. 178... FOR PACKAGINGS Large Packagings Standards § 178.925 Standards for rigid plastic Large Packagings. (a) The provisions in this section apply to rigid plastic Large Packagings intended to contain liquids and...

  11. 49 CFR 178.925 - Standards for rigid plastic Large Packagings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Standards for rigid plastic Large Packagings. 178... FOR PACKAGINGS Large Packagings Standards § 178.925 Standards for rigid plastic Large Packagings. (a) The provisions in this section apply to rigid plastic Large Packagings intended to contain liquids and...

  12. 49 CFR 178.925 - Standards for rigid plastic Large Packagings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Standards for rigid plastic Large Packagings. 178... FOR PACKAGINGS Large Packagings Standards § 178.925 Standards for rigid plastic Large Packagings. (a) The provisions in this section apply to rigid plastic Large Packagings intended to contain liquids and...

  13. 49 CFR 178.925 - Standards for rigid plastic Large Packagings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Standards for rigid plastic Large Packagings. 178... FOR PACKAGINGS Large Packagings Standards § 178.925 Standards for rigid plastic Large Packagings. (a) The provisions in this section apply to rigid plastic Large Packagings intended to contain liquids and...

  14. Roles for Cardiac MyBP-C in Maintaining Myofilament Lattice Rigidity and Prolonging Myosin Cross-Bridge Lifetime

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

    Palmer, B.M.; Sadayappan, S.; Wang, Y.

    2011-10-06

    We investigated the influence of cardiac myosin binding protein-C (cMyBP-C) and its constitutively unphosphorylated status on the radial and longitudinal stiffnesses of the myofilament lattice in chemically skinned myocardial strips of the following mouse models: nontransgenic (NTG), effective null for cMyBP-C (t/t), wild-type cMyBP-C expressed into t/t (WT{sub t/t}), and constitutively unphosphorylated cMyBP-C (AllP{sub -t/t}). We found that the absence of cMyBP-C in the t/t and the unphosphorylated cMyBP-C in the AllP{sub -t/t} resulted in a compressible cardiac myofilament lattice induced by rigor not observed in the NTG and WT{sub t/t}. These results suggest that the presence and phosphorylation ofmore » the N-terminus of cMyBP-C provides structural support and radial rigidity to the myofilament lattice. Examination of myofilament longitudinal stiffness under rigor conditions demonstrated a significant reduction in cross-bridge-dependent stiffness in the t/t compared with NTG controls, but not in the AllP{sub -t/t} compared with WT{sub t/t} controls. The absence of cMyBP-C in the t/t and the unphosphorylated cMyBP-C in the AllP{sub -t/t} both resulted in a shorter myosin cross-bridge lifetime when myosin isoform was controlled. These data collectively suggest that cMyBP-C provides radial rigidity to the myofilament lattice through the N-terminus, and that disruption of the phosphorylation of cMyBP-C is sufficient to abolish this structural role of the N-terminus and shorten cross-bridge lifetime. Although the presence of cMyBP-C also provides longitudinal rigidity, phosphorylation of the N-terminus is not necessary to maintain longitudinal rigidity of the lattice, in contrast to radial rigidity.« less

  15. Rigid body formulation in a finite element context with contact interaction

    NASA Astrophysics Data System (ADS)

    Refachinho de Campos, Paulo R.; Gay Neto, Alfredo

    2018-03-01

    The present work proposes a formulation to employ rigid bodies together with flexible bodies in the context of a nonlinear finite element solver, with contact interactions. Inertial contributions due to distribution of mass of a rigid body are fully developed, considering a general pole position associated with a single node, representing a rigid body element. Additionally, a mechanical constraint is proposed to connect a rigid region composed by several nodes, which is useful for linking rigid/flexible bodies in a finite element environment. Rodrigues rotation parameters are used to describe finite rotations, by an updated Lagrangian description. In addition, the contact formulation entitled master-surface to master-surface is employed in conjunction with the rigid body element and flexible bodies, aiming to consider their interaction in a rigid-flexible multibody environment. New surface parameterizations are presented to establish contact pairs, permitting pointwise interaction in a frictional scenario. Numerical examples are provided to show robustness and applicability of the methods.

  16. Taichi-inspired rigid-flexible coupling cellulose-supported solid polymer electrolyte for high-performance lithium batteries

    PubMed Central

    Zhang, Jianjun; Yue, Liping; Hu, Pu; Liu, Zhihong; Qin, Bingsheng; Zhang, Bo; Wang, Qingfu; Ding, Guoliang; Zhang, Chuanjian; Zhou, Xinhong; Yao, Jianhua; Cui, Guanglei; Chen, Liquan

    2014-01-01

    Inspired by Taichi, we proposed rigid-flexible coupling concept and herein developed a highly promising solid polymer electrolyte comprised of poly (ethylene oxide), poly (cyano acrylate), lithium bis(oxalate)borate and robust cellulose nonwoven. Our investigation revealed that this new class solid polymer electrolyte possessed comprehensive properties in high mechanical integrity strength, sufficient ionic conductivity (3 × 10−4 S cm−1) at 60°C and improved dimensional thermostability (up to 160°C). In addition, the lithium iron phosphate (LiFePO4)/lithium (Li) cell using such solid polymer electrolyte displayed superior rate capacity (up to 6 C) and stable cycle performance at 80°C. Furthermore, the LiFePO4/Li battery could also operate very well even at an elevated temperature of 160°C, thus improving enhanced safety performance of lithium batteries. The use of this solid polymer electrolyte mitigates the safety risk and widens the operation temperature range of lithium batteries. Thus, this fascinating study demonstrates a proof of concept of the use of rigid-flexible coupling solid polymer electrolyte toward practical lithium battery applications with improved reliability and safety. PMID:25183416

  17. Great apes select tools on the basis of their rigidity.

    PubMed

    Manrique, Héctor Marín; Gross, Alexandra Nam-Mi; Call, Josep

    2010-10-01

    Wild chimpanzees select tools according to their rigidity. However, little is known about whether choices are solely based on familiarity with the materials or knowledge about tool properties. Furthermore, it is unclear whether tool manipulation is required prior to selection or whether observation alone can suffice. We investigated whether chimpanzees (Pan troglodytes) (n = 9), bonobos (Pan paniscus) (n = 4), orangutans (Pongo pygmaeus) (n = 6), and gorillas (Gorilla gorilla) (n = 2) selected new tools on the basis of their rigidity. Subjects faced an out-of-reach reward and a choice of three tools differing in color, diameter, material, and rigidity. We used 10 different 3-tool sets (1 rigid, 2 flexible). Subjects were unfamiliar with the tools and needed to select and use the rigid tool to retrieve the reward. Experiment 1 showed that subjects chose the rigid tool from the first trial with a 90% success rate. Experiments 2a and 2b addressed the role of manipulation and observation in tool selection. Subjects performed equally well in conditions in which they could manipulate the tools themselves or saw the experimenter manipulate the tools but decreased their performance if they could only visually inspect the tools. Experiment 3 showed that subjects could select flexible tools (as opposed to rigid ones) to meet new task demands. We conclude that great apes spontaneously selected unfamiliar rigid or flexible tools even after gathering minimal observational information. 2010 APA, all rights reserved

  18. Non-rigid image registration using graph-cuts.

    PubMed

    Tang, Tommy W H; Chung, Albert C S

    2007-01-01

    Non-rigid image registration is an ill-posed yet challenging problem due to its supernormal high degree of freedoms and inherent requirement of smoothness. Graph-cuts method is a powerful combinatorial optimization tool which has been successfully applied into image segmentation and stereo matching. Under some specific constraints, graph-cuts method yields either a global minimum or a local minimum in a strong sense. Thus, it is interesting to see the effects of using graph-cuts in non-rigid image registration. In this paper, we formulate non-rigid image registration as a discrete labeling problem. Each pixel in the source image is assigned a displacement label (which is a vector) indicating which position in the floating image it is spatially corresponding to. A smoothness constraint based on first derivative is used to penalize sharp changes in displacement labels across pixels. The whole system can be optimized by using the graph-cuts method via alpha-expansions. We compare 2D and 3D registration results of our method with two state-of-the-art approaches. It is found that our method is more robust to different challenging non-rigid registration cases with higher registration accuracy.

  19. Rigidity of transmembrane proteins determines their cluster shape

    NASA Astrophysics Data System (ADS)

    Jafarinia, Hamidreza; Khoshnood, Atefeh; Jalali, Mir Abbas

    2016-01-01

    Protein aggregation in cell membrane is vital for the majority of biological functions. Recent experimental results suggest that transmembrane domains of proteins such as α -helices and β -sheets have different structural rigidities. We use molecular dynamics simulation of a coarse-grained model of protein-embedded lipid membranes to investigate the mechanisms of protein clustering. For a variety of protein concentrations, our simulations under thermal equilibrium conditions reveal that the structural rigidity of transmembrane domains dramatically affects interactions and changes the shape of the cluster. We have observed stable large aggregates even in the absence of hydrophobic mismatch, which has been previously proposed as the mechanism of protein aggregation. According to our results, semiflexible proteins aggregate to form two-dimensional clusters, while rigid proteins, by contrast, form one-dimensional string-like structures. By assuming two probable scenarios for the formation of a two-dimensional triangular structure, we calculate the lipid density around protein clusters and find that the difference in lipid distribution around rigid and semiflexible proteins determines the one- or two-dimensional nature of aggregates. It is found that lipids move faster around semiflexible proteins than rigid ones. The aggregation mechanism suggested in this paper can be tested by current state-of-the-art experimental facilities.

  20. Method of preparing porous, rigid ceramic separators for an electrochemical cell. [Patent application

    DOEpatents

    Bandyopadhyay, G.; Dusek, J.T.

    Porous, rigid separators for electrochemical cells are prepared by first calcining particles of ceramic material at temperatures above about 1200/sup 0/C for a sufficient period of time to reduce the sinterability of the particles. A ceramic powder that has not been calcined is blended with the original powder to control the porosity of the completed separator. The ceramic blend is then pressed into a sheet of the desired shape and sintered at a temperature somewhat lower than the calcination temperature. Separator sheets of about 1 to 2.5 mm thickness and 30 to 70% porosity can be prepared by this technique. Ceramics such as yttria, magnesium oxide, and magnesium-aluminium oxide have advantageously been used to form separators by this method.

  1. Rigid-Cluster Models of Conformational Transitions in Macromolecular Machines and Assemblies

    PubMed Central

    Kim, Moon K.; Jernigan, Robert L.; Chirikjian, Gregory S.

    2005-01-01

    We present a rigid-body-based technique (called rigid-cluster elastic network interpolation) to generate feasible transition pathways between two distinct conformations of a macromolecular assembly. Many biological molecules and assemblies consist of domains which act more or less as rigid bodies during large conformational changes. These collective motions are thought to be strongly related with the functions of a system. This fact encourages us to simply model a macromolecule or assembly as a set of rigid bodies which are interconnected with distance constraints. In previous articles, we developed coarse-grained elastic network interpolation (ENI) in which, for example, only Cα atoms are selected as representatives in each residue of a protein. We interpolate distance differences of two conformations in ENI by using a simple quadratic cost function, and the feasible conformations are generated without steric conflicts. Rigid-cluster interpolation is an extension of the ENI method with rigid-clusters replacing point masses. Now the intermediate conformations in an anharmonic pathway can be determined by the translational and rotational displacements of large clusters in such a way that distance constraints are observed. We present the derivation of the rigid-cluster model and apply it to a variety of macromolecular assemblies. Rigid-cluster ENI is then modified for a hybrid model represented by a mixture of rigid clusters and point masses. Simulation results show that both rigid-cluster and hybrid ENI methods generate sterically feasible pathways of large systems in a very short time. For example, the HK97 virus capsid is an icosahedral symmetric assembly composed of 60 identical asymmetric units. Its original Hessian matrix size for a Cα coarse-grained model is >(300,000)2. However, it reduces to (84)2 when we apply the rigid-cluster model with icosahedral symmetry constraints. The computational cost of the interpolation no longer scales heavily with the size

  2. Geometric and electrostatic modeling using molecular rigidity functions

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

    Mu, Lin; Xia, Kelin; Wei, Guowei

    Geometric and electrostatic modeling is an essential component in computational biophysics and molecular biology. Commonly used geometric representations admit geometric singularities such as cusps, tips and self-intersecting facets that lead to computational instabilities in the molecular modeling. Our present work explores the use of flexibility and rigidity index (FRI), which has a proved superiority in protein B-factor prediction, for biomolecular geometric representation and associated electrostatic analysis. FRI rigidity surfaces are free of geometric singularities. We propose a rigidity based Poisson–Boltzmann equation for biomolecular electrostatic analysis. These approaches to surface and electrostatic modeling are validated by a set of 21 proteins.more » Our results are compared with those of established methods. Finally, being smooth and analytically differentiable, FRI rigidity functions offer excellent curvature analysis, which characterizes concave and convex regions on protein surfaces. Polarized curvatures constructed by using the product of minimum curvature and electrostatic potential is shown to predict potential protein–ligand binding sites.« less

  3. Geometric and electrostatic modeling using molecular rigidity functions

    DOE PAGES

    Mu, Lin; Xia, Kelin; Wei, Guowei

    2017-03-01

    Geometric and electrostatic modeling is an essential component in computational biophysics and molecular biology. Commonly used geometric representations admit geometric singularities such as cusps, tips and self-intersecting facets that lead to computational instabilities in the molecular modeling. Our present work explores the use of flexibility and rigidity index (FRI), which has a proved superiority in protein B-factor prediction, for biomolecular geometric representation and associated electrostatic analysis. FRI rigidity surfaces are free of geometric singularities. We propose a rigidity based Poisson–Boltzmann equation for biomolecular electrostatic analysis. These approaches to surface and electrostatic modeling are validated by a set of 21 proteins.more » Our results are compared with those of established methods. Finally, being smooth and analytically differentiable, FRI rigidity functions offer excellent curvature analysis, which characterizes concave and convex regions on protein surfaces. Polarized curvatures constructed by using the product of minimum curvature and electrostatic potential is shown to predict potential protein–ligand binding sites.« less

  4. 21 CFR 890.3610 - Rigid pneumatic structure orthosis.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid pneumatic structure orthosis. 890.3610 Section 890.3610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3610 Rigid...

  5. 21 CFR 890.3610 - Rigid pneumatic structure orthosis.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rigid pneumatic structure orthosis. 890.3610 Section 890.3610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3610 Rigid...

  6. 21 CFR 890.3610 - Rigid pneumatic structure orthosis.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Rigid pneumatic structure orthosis. 890.3610 Section 890.3610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3610 Rigid...

  7. 21 CFR 890.3610 - Rigid pneumatic structure orthosis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Rigid pneumatic structure orthosis. 890.3610 Section 890.3610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3610 Rigid...

  8. 21 CFR 890.3610 - Rigid pneumatic structure orthosis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Rigid pneumatic structure orthosis. 890.3610 Section 890.3610 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3610 Rigid...

  9. Flexible band versus rigid ring annuloplasty for functional tricuspid regurgitation

    PubMed Central

    Izutani, Hironori; Nakamura, Teruya; Kawachi, Kanji

    2010-01-01

    We review and compare our experience with tricuspid ring annuloplasty between usage of the Cosgrove-Edwards flexible band and the MC3 rigid ring for repair of functional tricuspid regurgitation to determine the efficacy and mid-term durability of tricuspid annuloplasty. 117 patients with functional tricuspid regurgitation undergoing open heart surgery and tricuspid valve repair from May 2005 to December 2007 were reviewed. The flexible bands were used in thirty five patients before October 2006. Since then, the rigid rings were used in the next consecutive eighty two cases. Echocardiographic evaluation of tricuspid regurgitation was performed preoperatively and postoperatively in follow-up schedule. The degree of tricuspid regurgitation was reduced from 2.80±0.67 to 0.71±1.0 (regurgitation severity grade: 0 to 4) in the patients with flexible bands at discharge. It was from 2.68±0.70 to 0.22±0.60 in the patients with rigid rings. At thirty six months postoperative period, tricuspid regurgitation grades in patients with flexible bands and rigid rings were 0.80±0.95 and 0.36±0.77, respectively. Freedom from recurrent tricuspid regurgitation (grade 2 or 3) in patients with flexible bands and rigid rings were 68.6% and 87.8%, respectively. Recurrent tricuspid regurgitation was significantly lower in the patients with rigid rings. Although both flexible band and rigid ring annuloplasty provide low rate of recurrent tricuspid regurgitation, rigid ring annuloplasty might be more effective than flexible band annuloplasty for decreasing functional tricuspid regurgitation in immediate and mid-term postoperative periods. PMID:21977298

  10. A probabilistic model for detecting rigid domains in protein structures.

    PubMed

    Nguyen, Thach; Habeck, Michael

    2016-09-01

    Large-scale conformational changes in proteins are implicated in many important biological functions. These structural transitions can often be rationalized in terms of relative movements of rigid domains. There is a need for objective and automated methods that identify rigid domains in sets of protein structures showing alternative conformational states. We present a probabilistic model for detecting rigid-body movements in protein structures. Our model aims to approximate alternative conformational states by a few structural parts that are rigidly transformed under the action of a rotation and a translation. By using Bayesian inference and Markov chain Monte Carlo sampling, we estimate all parameters of the model, including a segmentation of the protein into rigid domains, the structures of the domains themselves, and the rigid transformations that generate the observed structures. We find that our Gibbs sampling algorithm can also estimate the optimal number of rigid domains with high efficiency and accuracy. We assess the power of our method on several thousand entries of the DynDom database and discuss applications to various complex biomolecular systems. The Python source code for protein ensemble analysis is available at: https://github.com/thachnguyen/motion_detection : mhabeck@gwdg.de. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  11. Rigid Body Motion in Stereo 3D Simulation

    ERIC Educational Resources Information Center

    Zabunov, Svetoslav

    2010-01-01

    This paper addresses the difficulties experienced by first-grade students studying rigid body motion at Sofia University. Most quantities describing the rigid body are in relations that the students find hard to visualize and understand. They also lose the notion of cause-result relations between vector quantities, such as the relation between…

  12. Auxetic behaviour from rotating rigid units

    NASA Astrophysics Data System (ADS)

    Grima, J. N.; Alderson, A.; Evans, K. E.

    2005-03-01

    Auxetic materials exhibit the unexpected feature of becoming fatter when stretched and narrower when compressed, in other words, they exhibit a negative Poisson's ratio. This counter-intuitive behaviour imparts many beneficial effects on the material's macroscopic properties that make auxetics superior to conventional materials in many commercial applications. Recent research suggests that auxetic be-haviour generally results from a cooperative effect between the material's internal structure (geometry setup) and the deformation mechanism it undergoes when submitted to a stress. Auxetic behaviour is also known to be scale-independent, and thus, the same geometry/deformation mechanism may operate at the macro-, micro- and nano- (molecular) level. A considerable amount of research has been focused on the re-entrant honeycomb structure which exhibits auxetic behaviour if deformed through hinging at the joints or flexure of the ribs, and it was proposed that this re-entrant geometry plays an impor- tant role in generating auxetic behaviour in various forms of materials ranging from nanostructured polymers to foams. This paper discusses an alternative mode of deformation involving rotating rigid units which also results in negative Poisson's ratios. In its most ideal form, this mechanism may be construc- ted in two dimensions using rigid polygons connected together through hinges at their vertices. On application of uniaxial loads, these rigid polygons rotate with respect to each other to form a more open structure hence giving rise to a negative Poisson's ratio. This paper also discusses the role that rotating rigid units are thought to have in various classes of materials to give rise to negative Poisson's ratios.

  13. High Resolution Quantification of Cellular Forces for Rigidity Sensing

    NASA Astrophysics Data System (ADS)

    Liu, Shuaimin

    This thesis describes a comprehensive study of understanding the mechanism of rigidity sensing by quantitative analysis using submicron pillar array substrates. From mechanobiology perspective, we explore and study molecular pathways involved in rigidity and force sensing at cell-matrix adhesions with regard to cancer, regeneration, and development by quantification methods. In Chapter 2 and 3, we developed fabrication and imaging techniques to enhance the performance of a submicron pillar device in terms of spatial and temporal measurement ability, and we discovered a correlation of rigidity sensing forces and corresponding proteins involved in the early rigidity sensing events. In Chapter 2, we introduced optical effect arising from submicron structure imaging, and we described a technique to identify the correct focal plane of pillar tip by fabricating a substrate with designed-offset pillars. From calibration result, we identified the correct focal plane that was previously overlooked, and verified our findings by other imaging techniques. In Chapter 3, we described several techniques to selectively functionalize elastomeric pillars top and compared these techniques in terms of purposes and fabrication complexity. Techniques introduced in this chapter included direct labeling, such as stamping of fluorescent substances (organic dye, nano-diamond, q-dot) to pillars top, as well as indirect labeling that selectively modify the surface of molds with either metal or fluorescent substances. In Chapter 4, we examined the characteristics of local contractility forces and identified the components formed a sarcomere like contractile unit (CU) that cells use to sense rigidity. CUs were found to be assembled at cell edge, contain myosin II, alpha-actinin, tropomodulin and tropomyosin (Tm), and resemble sarcomeres in size (˜2 mum) and function. Then we performed quantitative analysis of CUs to evaluate rigidity sensing activity over ˜8 hours time course and found that

  14. Construction of the Non-Rigid Earth Rotation Series

    NASA Astrophysics Data System (ADS)

    Pashkevich, V. V.

    2007-01-01

    Last years a lot of attempts to derive a high-precision theory of the non-rigid Earth rotation are carried out. For these purposes different transfer functions are used. Usually these transfer functions are applied to the series representing the nutation in the longitude and the obliquity of the rigid Earth rotation with respect to the ecliptic of date. The aim of this investigation is a construction of new high-precision non-rigid Earth rotation series (SN9000), dynamically adequate to the DE404/LE404 ephemeris over 2000 time span years, which are presented as functions of the Euler angles Ψ, θ and φ with respect to the fixed ecliptic plane and equinox J2000.0.

  15. Rigidity of outermost MOTS: the initial data version

    NASA Astrophysics Data System (ADS)

    Galloway, Gregory J.

    2018-03-01

    In the paper Commun Anal Geom 16(1):217-229, 2008, a rigidity result was obtained for outermost marginally outer trapped surfaces (MOTSs) that do not admit metrics of positive scalar curvature. This allowed one to treat the "borderline case" in the author's work with R. Schoen concerning the topology of higher dimensional black holes (Commun Math Phys 266(2):571-576, 2006). The proof of this rigidity result involved bending the initial data manifold in the vicinity of the MOTS within the ambient spacetime. In this note we show how to circumvent this step, and thereby obtain a pure initial data version of this rigidity result and its consequence concerning the topology of black holes.

  16. Utility of semi-rigid thoracoscopy in undiagnosed exudative pleural effusion.

    PubMed

    Nattusamy, Loganathan; Madan, Karan; Mohan, Anant; Hadda, Vijay; Jain, Deepali; Madan, Neha Kawatra; Arava, Sudheer; Khilnani, Gopi C; Guleria, Randeep

    2015-01-01

    Semi-rigid thoracoscopy is a safe and efficacious procedure in patients with undiagnosed pleural effusion. Literature on its utility from developing countries is limited. We herein describe our initial experience on the utility of semi-rigid thoracoscopy from a tertiary care teaching and referral center in north India. We also perform a systematic review of studies reporting the utility of semi-rigid thoracoscopy from India. The primary objective was to evaluate the diagnostic utility of semi-rigid thoracoscopy in patients with undiagnosed exudative pleural effusion. Semi-rigid thoracoscopy was performed under local anesthesia and conscious sedation in the bronchoscopy suite. A total of 48 patients underwent semi-rigid thoracoscopy between August 2012 and December 2013 for undiagnosed pleural effusion. Mean age was 50.9 ± 14.1 years (range: 17-78 years). Pre-procedure clinico-radiological diagnoses were malignant pleural effusion [36 patients (75%)], tuberculosis (TB) [10 (20.83%) patients], and empyema [2 patients (4.17%)]. Patients with empyema underwent the procedure for pleural biopsy, optimal placement of intercostal tube and adhesiolysis. Thoracoscopic pleural biopsy diagnosed pleural malignancy in 30 (62.5%) patients and TB in 2 (4.17%) patients. Fourteen (29.17%) patients were diagnosed with non-specific pleuritis and normal pleura was diagnosed on a pleural biopsy in 2 (4.17%) patients. Overall, a definitive diagnosis of either pleural malignancy or TB was obtained in 32 (66.7%) patients. Combined overall sensitivity, specificity, positive predictive value and negative predictive value of thoracoscopic pleural biopsy for malignant pleural effusion were 96.77%, 100%, 100% and 66.67%, respectively. There was no procedure-related mortality. On performing a systematic review of literature, four studies on semi-rigid thoracoscopy from India were identified. Semi-rigid thoracoscopy is a safe and efficacious procedure in patients with undiagnosed exudative

  17. Utility of semi-rigid thoracoscopy in undiagnosed exudative pleural effusion

    PubMed Central

    Nattusamy, Loganathan; Madan, Karan; Mohan, Anant; Hadda, Vijay; Jain, Deepali; Madan, Neha Kawatra; Arava, Sudheer; Khilnani, Gopi C; Guleria, Randeep

    2015-01-01

    Background: Semi-rigid thoracoscopy is a safe and efficacious procedure in patients with undiagnosed pleural effusion. Literature on its utility from developing countries is limited. We herein describe our initial experience on the utility of semi-rigid thoracoscopy from a tertiary care teaching and referral center in north India. We also perform a systematic review of studies reporting the utility of semi-rigid thoracoscopy from India. Patients and Methods: The primary objective was to evaluate the diagnostic utility of semi-rigid thoracoscopy in patients with undiagnosed exudative pleural effusion. Semi-rigid thoracoscopy was performed under local anesthesia and conscious sedation in the bronchoscopy suite. Results: A total of 48 patients underwent semi-rigid thoracoscopy between August 2012 and December 2013 for undiagnosed pleural effusion. Mean age was 50.9 ± 14.1 years (range: 17–78 years). Pre-procedure clinico-radiological diagnoses were malignant pleural effusion [36 patients (75%)], tuberculosis (TB) [10 (20.83%) patients], and empyema [2 patients (4.17%)]. Patients with empyema underwent the procedure for pleural biopsy, optimal placement of intercostal tube and adhesiolysis. Thoracoscopic pleural biopsy diagnosed pleural malignancy in 30 (62.5%) patients and TB in 2 (4.17%) patients. Fourteen (29.17%) patients were diagnosed with non-specific pleuritis and normal pleura was diagnosed on a pleural biopsy in 2 (4.17%) patients. Overall, a definitive diagnosis of either pleural malignancy or TB was obtained in 32 (66.7%) patients. Combined overall sensitivity, specificity, positive predictive value and negative predictive value of thoracoscopic pleural biopsy for malignant pleural effusion were 96.77%, 100%, 100% and 66.67%, respectively. There was no procedure-related mortality. On performing a systematic review of literature, four studies on semi-rigid thoracoscopy from India were identified. Conclusion: Semi-rigid thoracoscopy is a safe and

  18. 21 CFR 874.4710 - Esophagoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... generic type of device includes the flexible foreign body claw, flexible biopsy forceps, rigid biopsy curette, flexible biopsy brush, rigid biopsy forceps and flexible biopsy curette, but excludes the...

  19. 21 CFR 874.4710 - Esophagoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... generic type of device includes the flexible foreign body claw, flexible biopsy forceps, rigid biopsy curette, flexible biopsy brush, rigid biopsy forceps and flexible biopsy curette, but excludes the...

  20. 21 CFR 874.4760 - Nasopharyngoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., salpingoscope, flexible foreign body claw, flexible biopsy forceps, rigid biopsy curette, flexible biospy brush, rigid biopsy forceps and flexible biopsy curette, but excludes the fiberoptic light source and carrier...

  1. 21 CFR 874.4760 - Nasopharyngoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., salpingoscope, flexible foreign body claw, flexible biopsy forceps, rigid biopsy curette, flexible biospy brush, rigid biopsy forceps and flexible biopsy curette, but excludes the fiberoptic light source and carrier...

  2. 21 CFR 874.4760 - Nasopharyngoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., salpingoscope, flexible foreign body claw, flexible biopsy forceps, rigid biopsy curette, flexible biospy brush, rigid biopsy forceps and flexible biopsy curette, but excludes the fiberoptic light source and carrier...

  3. Bending Rigidity of 2D Silica.

    PubMed

    Büchner, C; Eder, S D; Nesse, T; Kuhness, D; Schlexer, P; Pacchioni, G; Manson, J R; Heyde, M; Holst, B; Freund, H-J

    2018-06-01

    A chemically stable bilayers of SiO_{2} (2D silica) is a new, wide band gap 2D material. Up till now graphene has been the only 2D material where the bending rigidity has been measured. Here we present inelastic helium atom scattering data from 2D silica on Ru(0001) and extract the first bending rigidity, κ, measurements for a nonmonoatomic 2D material of definable thickness. We find a value of κ=8.8  eV±0.5  eV which is of the same order of magnitude as theoretical values in the literature for freestanding crystalline 2D silica.

  4. Bending Rigidity of 2D Silica

    NASA Astrophysics Data System (ADS)

    Büchner, C.; Eder, S. D.; Nesse, T.; Kuhness, D.; Schlexer, P.; Pacchioni, G.; Manson, J. R.; Heyde, M.; Holst, B.; Freund, H.-J.

    2018-06-01

    A chemically stable bilayers of SiO2 (2D silica) is a new, wide band gap 2D material. Up till now graphene has been the only 2D material where the bending rigidity has been measured. Here we present inelastic helium atom scattering data from 2D silica on Ru(0001) and extract the first bending rigidity, κ , measurements for a nonmonoatomic 2D material of definable thickness. We find a value of κ =8.8 eV ±0.5 eV which is of the same order of magnitude as theoretical values in the literature for freestanding crystalline 2D silica.

  5. Genus Ranges of 4-Regular Rigid Vertex Graphs

    PubMed Central

    Buck, Dorothy; Dolzhenko, Egor; Jonoska, Nataša; Saito, Masahico; Valencia, Karin

    2016-01-01

    A rigid vertex of a graph is one that has a prescribed cyclic order of its incident edges. We study orientable genus ranges of 4-regular rigid vertex graphs. The (orientable) genus range is a set of genera values over all orientable surfaces into which a graph is embedded cellularly, and the embeddings of rigid vertex graphs are required to preserve the prescribed cyclic order of incident edges at every vertex. The genus ranges of 4-regular rigid vertex graphs are sets of consecutive integers, and we address two questions: which intervals of integers appear as genus ranges of such graphs, and what types of graphs realize a given genus range. For graphs with 2n vertices (n > 1), we prove that all intervals [a, b] for all a < b ≤ n, and singletons [h, h] for some h ≤ n, are realized as genus ranges. For graphs with 2n − 1 vertices (n ≥ 1), we prove that all intervals [a, b] for all a < b ≤ n except [0, n], and [h, h] for some h ≤ n, are realized as genus ranges. We also provide constructions of graphs that realize these ranges. PMID:27807395

  6. Understanding Rigid Geometric Transformations: Jeff's Learning Path for Translation

    ERIC Educational Resources Information Center

    Yanik, Huseyin Bahadir; Flores, Alfinio

    2009-01-01

    This article describes the development of knowledge and understanding of translations of Jeff, a prospective elementary teacher, during a teaching experiment that also included other rigid transformations. His initial conceptions of translations and other rigid transformations were characterized as undefined motions of a single object. He…

  7. 21 CFR 874.4680 - Bronchoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (flexible or rigid) and accessories. (a) Identification. A bronchoscope (flexible or rigid) and accessories... bronchoscope and is intended to examine or treat the larynx and tracheobronchial tree. It is typically used...

  8. Thin structured rigid body for acoustic absorption

    NASA Astrophysics Data System (ADS)

    Starkey, T. A.; Smith, J. D.; Hibbins, A. P.; Sambles, J. R.; Rance, H. J.

    2017-01-01

    We present a thin acoustic metamaterial absorber, comprised of only rigid metal and air, that gives rise to near unity absorption of airborne sound on resonance. This simple, easily fabricated, robust structure comprising a perforated metal plate separated from a rigid wall by a deeply subwavelength channel of air is an ideal candidate for a sound absorbing panel. The strong absorption in the system is attributed to the thermo-viscous losses arising from a sound wave guided between the plate and the wall, defining the subwavelength channel.

  9. Associative memory through rigid origami

    NASA Astrophysics Data System (ADS)

    Murugan, Arvind; Brenner, Michael

    2015-03-01

    Mechanisms such as Miura Ori have proven useful in diverse contexts since they have only one degree of freedom that is easily controlled. We combine the theory of rigid origami and associative memory in frustrated neural networks to create structures that can ``learn'' multiple generic folding mechanisms and yet can be robustly controlled. We show that such rigid origami structures can ``recall'' a specific learned mechanism when induced by a physical impulse that only need resemble the desired mechanism (i.e. robust recall through association). Such associative memory in matter, seen before in self-assembly, arises due to a balance between local promiscuity (i.e., many local degrees of freedom) and global frustration which minimizes interference between different learned behaviors. Origami with associative memory can lead to a new class of deployable structures and kinetic architectures with multiple context-dependent behaviors.

  10. Rigid external maxillary distraction and rhinoplasty for pyknodysostosis.

    PubMed

    Varol, Altan; Sabuncuoglu, Fidan Alakus; Sencimen, Metin; Akcam, Timur; Olmez, Hüseyin; Basa, Selçuk

    2011-05-01

    This article reports the treatment of an 33-year-old female patient with pyknodysostosis by rigid external distraction II midface distraction system. The patient with pyknodysostosis described in this report had severe midfacial hypoplasia. Correction of this by use of routine orthognathic surgery would require osteosynthesis and bone grafting. Risk of infection and/or nonunion after such a surgical procedure was considered too great, and therefore the possibility of treatment by distraction osteogenesis of the maxilla was evaluated. The rigid external distraction II midface distraction system was used to relocate the hypoplastic maxilla at anterior-inferior projection. Distraction osteogenesis should be considered as the primary reconstructive method for maxillofacial deformities in patients with sclerosing bone dysplasias, since this is the second reported case treated successfully with rigid external distraction.

  11. IFACEwat: the interfacial water-implemented re-ranking algorithm to improve the discrimination of near native structures for protein rigid docking

    PubMed Central

    2014-01-01

    . Conclusions With the inclusion of interfacial water, the IFACEwat improves mostly results of the initial rigid docking, especially for Antigen/Antibody complexes. The improvement is achieved by explicitly taking into account the contribution of water during the protein interactions, which was ignored or not fully presented by the initial rigid docking and other re-ranking techniques. In addition, the IFACEwat maintains sufficient computational efficiency of the initial docking algorithm, yet improves the ranks as well as the number of the near native structures found. As our implementation so far targeted to improve the results of ZDOCK3.0.2, and particularly for the Antigen/Antibody complexes, it is expected in the near future that more implementations will be conducted to be applicable for other initial rigid docking algorithms. PMID:25521441

  12. Sufficient Forecasting Using Factor Models

    PubMed Central

    Fan, Jianqing; Xue, Lingzhou; Yao, Jiawei

    2017-01-01

    We consider forecasting a single time series when there is a large number of predictors and a possible nonlinear effect. The dimensionality was first reduced via a high-dimensional (approximate) factor model implemented by the principal component analysis. Using the extracted factors, we develop a novel forecasting method called the sufficient forecasting, which provides a set of sufficient predictive indices, inferred from high-dimensional predictors, to deliver additional predictive power. The projected principal component analysis will be employed to enhance the accuracy of inferred factors when a semi-parametric (approximate) factor model is assumed. Our method is also applicable to cross-sectional sufficient regression using extracted factors. The connection between the sufficient forecasting and the deep learning architecture is explicitly stated. The sufficient forecasting correctly estimates projection indices of the underlying factors even in the presence of a nonparametric forecasting function. The proposed method extends the sufficient dimension reduction to high-dimensional regimes by condensing the cross-sectional information through factor models. We derive asymptotic properties for the estimate of the central subspace spanned by these projection directions as well as the estimates of the sufficient predictive indices. We further show that the natural method of running multiple regression of target on estimated factors yields a linear estimate that actually falls into this central subspace. Our method and theory allow the number of predictors to be larger than the number of observations. We finally demonstrate that the sufficient forecasting improves upon the linear forecasting in both simulation studies and an empirical study of forecasting macroeconomic variables. PMID:29731537

  13. Discriminating Rigid from Nonrigid Motion

    DTIC Science & Technology

    1989-07-31

    motion can be given a three-dimensional interpretation using a constraint of rigidity. Kruppa’s result and others (Faugeras & Maybank , 1989; Huang...Experimental Psychology: Human Perception and Performance, 10, 1-11. Faugeras, 0., & Maybank , S. (1989). Motion from point matches: multiplicity of

  14. Elasticity of Relativistic Rigid Bodies?

    NASA Astrophysics Data System (ADS)

    Smarandache, Florentin

    2013-10-01

    In the classical Twin Paradox, according to the Special Theory of Relativity, when the traveling twin blasts off from the Earth to a relative velocity v =√{/3 } 2 c with respect to the Earth, his measuring stick and other physical objects in the direction of relative motion shrink to half their lengths. How is that possible in the real physical world to have let's say a rigid rocket shrinking to half and then later elongated back to normal as an elastic material when it stops? What is the explanation for the traveler's measuring stick and other physical objects, in effect, return to the same length to their original length in the Stay-At-Home, but there is no record of their having shrunk? If it's a rigid (not elastic) object, how can it shrink and then elongate back to normal? It might get broken in such situation.

  15. Hydrodynamics of a flexible plate between pitching rigid plates

    NASA Astrophysics Data System (ADS)

    Kim, Junyoung; Kim, Daegyoum

    2017-11-01

    The dynamics of a flexible plate have been studied as a model problem in swimming and flying of animals and fluid-structure interaction of plants and flags. Motivated by fish schooling and an array of sea grasses, we investigate the dynamics of a flexible plate closely placed between two pitching rigid plates. In most studies on passive deformation of the flexible plate, the plate is immersed in a uniform flow or a wavy flow. However, in this study, the flexible plate experiences periodic deformation by the oscillatory flow generated by the prescribed pitching motion of the rigid plates. In our model, the pitching axes of the rigid plates and the clamping position of the flexible plate are aligned on the same line. The flexible plate shows various responses depending on length and pitching frequency of rigid plates, thickness of a flexible plate, and free-stream velocity. To find the effect of each variable on the response of the flexible plate, amplitude of a trailing edge and modal contribution of a flapping motion are compared, and flow structure around the flexible plate is examined.

  16. NONUNIFORM FOURIER TRANSFORMS FOR RIGID-BODY AND MULTI-DIMENSIONAL ROTATIONAL CORRELATIONS

    PubMed Central

    BAJAJ, CHANDRAJIT; BAUER, BENEDIKT; BETTADAPURA, RADHAKRISHNA; VOLLRATH, ANTJE

    2013-01-01

    The task of evaluating correlations is central to computational structural biology. The rigid-body correlation problem seeks the rigid-body transformation (R, t), R ∈ SO(3), t ∈ ℝ3 that maximizes the correlation between a pair of input scalar-valued functions representing molecular structures. Exhaustive solutions to the rigid-body correlation problem take advantage of the fast Fourier transform to achieve a speedup either with respect to the sought translation or rotation. We present PFcorr, a new exhaustive solution, based on the non-equispaced SO(3) Fourier transform, to the rigid-body correlation problem; unlike previous solutions, ours achieves a combination of translational and rotational speedups without requiring equispaced grids. PFcorr can be straightforwardly applied to a variety of problems in protein structure prediction and refinement that involve correlations under rigid-body motions of the protein. Additionally, we show how it applies, along with an appropriate flexibility model, to analogs of the above problems in which the flexibility of the protein is relevant. PMID:24379643

  17. Correlation of impression removal force with elastomeric impression material rigidity and hardness.

    PubMed

    Walker, Mary P; Alderman, Nick; Petrie, Cynthia S; Melander, Jennifer; McGuire, Jacob

    2013-07-01

    Difficult impression removal has been linked to high rigidity and hardness of elastomeric impression materials. In response to this concern, manufacturers have reformulated their materials to reduce rigidity and hardness to decrease removal difficulty; however, the relationship between impression removal and rigidity or hardness has not been evaluated. The purpose of this study was to determine if there is a positive correlation between impression removal difficulty and rigidity or hardness of current elastomeric impression materials. Light- and medium-body polyether (PE), vinylpolysiloxane (VPS), and hybrid vinyl polyether siloxane (VPES) impression materials were tested (n = 5 for each material/consistency/test method). Rigidity (elastic modulus) was measured via tensile testing of dumbbell-shaped specimens (Die C, ASTM D412). Shore A hardness was measured using disc specimens according to ASTM D2240-05 test specifications. Impressions were also made of a custom stainless steel model using a custom metal tray that could be attached to a universal tester to measure associated removal force. Within each impression material consistency, one-factor ANOVA and Tukey's post hoc analyses (α = 0.05) were used to compare rigidity, hardness, and removal force of the three types of impression materials. A Pearson's correlation (α = 0.05) was used to evaluate the association between impression removal force and rigidity or hardness. With medium-body materials, VPS exhibited significantly higher (p ≤ 0.05) rigidity and hardness than VPES or PE, while PE impressions required significantly higher (p ≤ 0.05) removal force than VPS or VPES impressions. With light-body materials, VPS again demonstrated significantly higher (p ≤ 0.05) hardness than VPES or PE, while the rigidity of the light-body materials did not significantly differ between materials (p > 0.05); however, just as with the medium-body materials, light-body PE impressions required significantly higher (p

  18. Rigidity of the magic pentagram game

    NASA Astrophysics Data System (ADS)

    Kalev, Amir; Miller, Carl A.

    2018-01-01

    A game is rigid if a near-optimal score guarantees, under the sole assumption of the validity of quantum mechanics, that the players are using an approximately unique quantum strategy. Rigidity has a vital role in quantum cryptography as it permits a strictly classical user to trust behavior in the quantum realm. This property can be traced back as far as 1998 (Mayers and Yao) and has been proved for multiple classes of games. In this paper we prove ridigity for the magic pentagram game, a simple binary constraint satisfaction game involving two players, five clauses and ten variables. We show that all near-optimal strategies for the pentagram game are approximately equivalent to a unique strategy involving real Pauli measurements on three maximally-entangled qubit pairs.

  19. Rigidity of the magic pentagram game.

    PubMed

    Kalev, Amir; Miller, Carl A

    2018-01-01

    A game is rigid if a near-optimal score guarantees, under the sole assumption of the validity of quantum mechanics, that the players are using an approximately unique quantum strategy. Rigidity has a vital role in quantum cryptography as it permits a strictly classical user to trust behavior in the quantum realm. This property can be traced back as far as 1998 (Mayers and Yao) and has been proved for multiple classes of games. In this paper we prove ridigity for the magic pentagram game, a simple binary constraint satisfaction game involving two players, five clauses and ten variables. We show that all near-optimal strategies for the pentagram game are approximately equivalent to a unique strategy involving real Pauli measurements on three maximally-entangled qubit pairs.

  20. Elastic properties of rigid fiber-reinforced composites

    NASA Astrophysics Data System (ADS)

    Chen, J.; Thorpe, M. F.; Davis, L. C.

    1995-05-01

    We study the elastic properties of rigid fiber-reinforced composites with perfect bonding between fibers and matrix, and also with sliding boundary conditions. In the dilute region, there exists an exact analytical solution. Around the rigidity threshold we find the elastic moduli and Poisson's ratio by decomposing the deformation into a compression mode and a rotation mode. For perfect bonding, both modes are important, whereas only the compression mode is operative for sliding boundary conditions. We employ the digital-image-based method and a finite element analysis to perform computer simulations which confirm our analytical predictions.

  1. Non-rigid alignment in electron tomography in materials science.

    PubMed

    Printemps, Tony; Bernier, Nicolas; Bleuet, Pierre; Mula, Guido; Hervé, Lionel

    2016-09-01

    Electron tomography is a key technique that enables the visualization of an object in three dimensions with a resolution of about a nanometre. High-quality 3D reconstruction is possible thanks to the latest compressed sensing algorithms and/or better alignment and preprocessing of the 2D projections. Rigid alignment of 2D projections is routine in electron tomography. However, it cannot correct misalignments induced by (i) deformations of the sample due to radiation damage or (ii) drifting of the sample during the acquisition of an image in scanning transmission electron microscope mode. In both cases, those misalignments can give rise to artefacts in the reconstruction. We propose a simple-to-implement non-rigid alignment technique to correct those artefacts. This technique is particularly suited for needle-shaped samples in materials science. It is initiated by a rigid alignment of the projections and it is then followed by several rigid alignments of different parts of the projections. Piecewise linear deformations are applied to each projection to force them to simultaneously satisfy the rigid alignments of the different parts. The efficiency of this technique is demonstrated on three samples, an intermetallic sample with deformation misalignments due to a high electron dose typical to spectroscopic electron tomography, a porous silicon sample with an extremely thin end particularly sensitive to electron beam and another porous silicon sample that was drifting during image acquisitions. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

  2. Enhanced rigid-bond restraints

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

    Thorn, Andrea; Dittrich, Birger; Sheldrick, George M., E-mail: gsheldr@shelx.uni-ac.gwdg.de

    2012-07-01

    An extension is proposed to the rigid-bond description of atomic thermal motion in crystals. The rigid-bond model [Hirshfeld (1976 ▶). Acta Cryst. A32, 239–244] states that the mean-square displacements of two atoms are equal in the direction of the bond joining them. This criterion is widely used for verification (as intended by Hirshfeld) and also as a restraint in structure refinement as suggested by Rollett [Crystallographic Computing (1970 ▶), edited by F. R. Ahmed et al., pp. 167–181. Copenhagen: Munksgaard]. By reformulating this condition, so that the relative motion of the two atoms is required to be perpendicular to themore » bond, the number of restraints that can be applied per anisotropic atom is increased from about one to about three. Application of this condition to 1,3-distances in addition to the 1,2-distances means that on average just over six restraints can be applied to the six anisotropic displacement parameters of each atom. This concept is tested against very high resolution data of a small peptide and employed as a restraint for protein refinement at more modest resolution (e.g. 1.7 Å)« less

  3. Design requirements for rigid printed wiring boards and assemblies. NASA Handbook

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The NASA requirements for assuring reliable rigid printed wiring board design are prescribed. Basic considerations necessary to assure reliable rigid printed wiring board design are described and incorporated.

  4. [Subacute worsening of rigidity in a patient with Parkinson disease].

    PubMed

    Bekkelund, Svein Ivar; Lilleng, Hallvard; Arntzen, Kjell Arne

    2008-09-25

    In this paper we report a patient with Parkinson's disease (PD) presenting with subacute motor symptoms, especially rigidity. The 75-year-old man had relatively moderate PD for 12 years, which was treated with levodopa until he developed marked rigidity. The rigidity became worse, with prolonged off-periods, despite treatment with increased doses of levodopa. At the time of hospitalization he was unable to walk independently, but the clinical neurological examination only revealed aggravation of parkinsonian signs. MRI of the brain showed an intracerebral lesion, which was later confirmed as glioblastoma multiforme. The main feature was onset of marked rigidity a few weeks before severe tumour-specific symptoms developed, but spasticity or hyperreflexia were neither reported at the time of symptom exacerbation nor during hospitalization. This case demonstrates the importance of considering other underlying neurological disease in parkinsonian patients presenting with rapid progression of parkinsonian symptoms.

  5. 21 CFR 874.4760 - Nasopharyngoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... made of materials such as stainless steel and flexible plastic. This generic type of device includes..., salpingoscope, flexible foreign body claw, flexible biopsy forceps, rigid biopsy curette, flexible biospy brush, rigid biopsy forceps and flexible biopsy curette, but excludes the fiberoptic light source and carrier...

  6. 21 CFR 874.4760 - Nasopharyngoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... made of materials such as stainless steel and flexible plastic. This generic type of device includes..., salpingoscope, flexible foreign body claw, flexible biopsy forceps, rigid biopsy curette, flexible biospy brush, rigid biopsy forceps and flexible biopsy curette, but excludes the fiberoptic light source and carrier...

  7. Operative rigid bronchoscopy: indications, basic techniques and results.

    PubMed

    Petrella, Francesco; Borri, Alessandro; Casiraghi, Monica; Cavaliere, Sergio; Donghi, Stefano; Galetta, Domenico; Gasparri, Roberto; Guarize, Juliana; Pardolesi, Alessandro; Solli, Piergiorgio; Tessitore, Adele; Venturino, Marco; Veronesi, Giulia; Spaggiari, Lorenzo

    2014-05-27

    Palliative airway treatments are essential to improve quality and length of life in lung cancer patients with central airway obstruction. Rigid bronchoscopy has proved to be an excellent tool to provide airway access and control in this cohort of patients. The main indication for rigid bronchoscopy in adult bronchology remains central airway obstruction due to neoplastic or non-neoplastic disease. We routinely use negative pressure ventilation (NPV) under general anaesthesia to prevent intraoperative apnoea and respiratory acidosis. This procedure allows opioid sparing, a shorter recovery time and avoids manually assisted ventilation, thereby reducing the amount of oxygen needed, while maintaining optimal surgical conditions. The major indication for NPV rigid bronchoscopy at our institution has been airway obstruction by neoplastic tracheobronchial tissue, mainly treated by laser-assisted mechanical dissection. When strictly necessary, we use silicone stents for neoplastic or cicatricial strictures, reserving metal stents to cover tracheo-oesophageal fistulae. NPV rigid bronchoscopy is an excellent tool for the endoscopic treatment of locally advanced tumours of the lung, especially when patients have exhausted the conventional therapeutic resources. Laser-assisted mechanical resection and stent placement are the most effective procedures for preserving quality of life in patients with advanced stage cancer. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-thoracic Surgery. All rights reserved.

  8. Accuracy limit of rigid 3-point water models

    NASA Astrophysics Data System (ADS)

    Izadi, Saeed; Onufriev, Alexey V.

    2016-08-01

    Classical 3-point rigid water models are most widely used due to their computational efficiency. Recently, we introduced a new approach to constructing classical rigid water models [S. Izadi et al., J. Phys. Chem. Lett. 5, 3863 (2014)], which permits a virtually exhaustive search for globally optimal model parameters in the sub-space that is most relevant to the electrostatic properties of the water molecule in liquid phase. Here we apply the approach to develop a 3-point Optimal Point Charge (OPC3) water model. OPC3 is significantly more accurate than the commonly used water models of same class (TIP3P and SPCE) in reproducing a comprehensive set of liquid bulk properties, over a wide range of temperatures. Beyond bulk properties, we show that OPC3 predicts the intrinsic charge hydration asymmetry (CHA) of water — a characteristic dependence of hydration free energy on the sign of the solute charge — in very close agreement with experiment. Two other recent 3-point rigid water models, TIP3PFB and H2ODC, each developed by its own, completely different optimization method, approach the global accuracy optimum represented by OPC3 in both the parameter space and accuracy of bulk properties. Thus, we argue that an accuracy limit of practical 3-point rigid non-polarizable models has effectively been reached; remaining accuracy issues are discussed.

  9. Non-Rigid Structure Estimation in Trajectory Space from Monocular Vision

    PubMed Central

    Wang, Yaming; Tong, Lingling; Jiang, Mingfeng; Zheng, Junbao

    2015-01-01

    In this paper, the problem of non-rigid structure estimation in trajectory space from monocular vision is investigated. Similar to the Point Trajectory Approach (PTA), based on characteristic points’ trajectories described by a predefined Discrete Cosine Transform (DCT) basis, the structure matrix was also calculated by using a factorization method. To further optimize the non-rigid structure estimation from monocular vision, the rank minimization problem about structure matrix is proposed to implement the non-rigid structure estimation by introducing the basic low-rank condition. Moreover, the Accelerated Proximal Gradient (APG) algorithm is proposed to solve the rank minimization problem, and the initial structure matrix calculated by the PTA method is optimized. The APG algorithm can converge to efficient solutions quickly and lessen the reconstruction error obviously. The reconstruction results of real image sequences indicate that the proposed approach runs reliably, and effectively improves the accuracy of non-rigid structure estimation from monocular vision. PMID:26473863

  10. Optimal matrix rigidity for stress fiber polarization in stem cells

    PubMed Central

    Rehfeldt, F.; Brown, A. E. X.; Discher, D. E.; Safran, S. A.

    2010-01-01

    The shape and differentiation of human mesenchymal stem cells is especially sensitive to the rigidity of their environment; the physical mechanisms involved are unknown. A theoretical model and experiments demonstrate here that the polarization/alignment of stress-fibers within stem cells is a non-monotonic function of matrix rigidity. We treat the cell as an active elastic inclusion in a surrounding matrix whose polarizability, unlike dead matter, depends on the feedback of cellular forces that develop in response to matrix stresses. The theory correctly predicts the monotonic increase of the cellular forces with the matrix rigidity and the alignment of stress-fibers parallel to the long axis of cells. We show that the anisotropy of this alignment depends non-monotonically on matrix rigidity and demonstrate it experimentally by quantifying the orientational distribution of stress-fibers in stem cells. These findings offer a first physical insight for the dependence of stem cell differentiation on tissue elasticity. PMID:20563235

  11. Verification of the Rigidity of the Coulomb Field in Motion

    NASA Astrophysics Data System (ADS)

    Blinov, S. V.; Bulyzhenkov, I. É.

    2018-06-01

    Laplace, analyzing the stability of the Solar System, was the first to calculate that the velocity of the motion of force fields can significantly exceed the velocity of light waves. In electrodynamics, the Coulomb field should rigidly accompany its source for instantaneous force action in distant regions. Such rigid motion was recently inferred from experiments at the Frascati Beam Test Facility with short beams of relativistic electrons. The comments of the authors on their observations are at odds with the comments of theoreticians on retarded potentials, which motivates a detailed study of the positions of both sides. Predictions of measurements, based on the Lienard-Wiechert potentials, are used to propose an unambiguous scheme for testing the rigidity of the Coulomb field. Realization of the proposed experimental scheme could independently refute or support the assertions of the Italian physicists regarding the rigid motion of Coulomb fields and likewise the nondual field approach to macroscopic reality.

  12. Service life evaluation of rigid explosive transfer lines

    NASA Technical Reports Server (NTRS)

    Bement, L. J.; Kayser, E. G.; Schimmel, M. L.

    1983-01-01

    This paper describes a joint Army/NASA-sponsored research program on the service life evaluation of rigid explosive transfer lines. These transfer lines are used to initiate emergency crew escape functions on a wide variety of military and NASA aircraft. The purpose of this program was to determine quantitatively the effects of service, age, and degradation on rigid explosive transfer lines to allow responsible, conservative, service life determination. More than 800 transfer lines were removed from the U.S. Army AH-1G and AH-1S, the U.S. Air Force B-1 and F-111, and the U.S. Navy F-14 aircraft for testing. The results indicated that the lines were not adversely affected by age, service, or a repeat of the thermal qualification tests on full-service lines. Extension of the service life of rigid explosive transfer lines should be considered, since considerable cost savings could be realized with no measurable decrease in system reliability.

  13. Fire and ecotoxicological aspects of polyurethane rigid foam.

    PubMed

    Wittbecker, F W; Giersig, M

    2001-01-01

    The main characteristics of fire effluents from polyurethane (PUR) foams are comparable to those from natural materials like wood, cork, or wool. This similarity has been demonstrated by comparative data from analytical and toxicological studies. It is therefore presumed that effluents of these materials present similar hazards to human beings and the environment. In almost all fires, dioxins can be found in the smoke and residues. In fires involving PURs, relevant quantities of halogenated dioxins or furans are not to be expected; this has been confirmed by investigations under controlled laboratory conditions. The insulation properties of rigid PUR foam contribute significantly to environmental protection and the conservation of resources. A number of methods for reusing and recycling PUR rigid foam waste have been developed and realized in practise. The possibilities range from reusing the material itself, generating liquid raw materials, and thermal recycling, even for (H)CFC-containing PUR rigid foams, by cocombustion in suitable plants.

  14. Fluid-Structure Interactions with Flexible and Rigid Bodies

    NASA Astrophysics Data System (ADS)

    Daily, David Jesse

    Fluid structure interactions occur to some extent in nearly every type of fluid flow. Understanding how structures interact with fluids and visa-versa is of vital importance in many engineering applications. The purpose of this research is to explore how fluids interact with flexible and rigid structures. A computational model was used to model the fluid structure interactions of vibrating synthetic vocal folds. The model simulated the coupling of the fluid and solid domains using a fluid-structure interface boundary condition. The fluid domain used a slightly compressible flow solver to allow for the possibility of acoustic coupling with the subglottal geometry and vibration of the vocal fold model. As the subglottis lengthened, the frequency of vibration decreased until a new acoustic mode could form in the subglottis. Synthetic aperture particle image velocimetry (SAPIV) is a three-dimensional particle tracking technique. SAPIV was used to image the jet of air that emerges from vibrating human vocal folds (glottal jet) during phonation. The three-dimensional reconstruction of the glottal jet found faint evidence of flow characteristics seen in previous research, such as axis-switching, but did not have sufficient resolution to detect small features. SAPIV was further applied to reconstruct the smaller flow characteristics of the glottal jet of vibrating synthetic vocal folds. Two- and four-layer synthetic vocal fold models were used to determine how the glottal jet from the synthetic models compared to the glottal jet from excised human vocal folds. The two- and four-layer models clearly exhibited axis-switching which has been seen in other 3D analyses of the glottal jet. Cavitation in a quiescent fluid can break a rigid structure such as a glass bottle. A new cavitation number was derived to include acceleration and pressure head at cavitation onset. A cavitation stick was used to validate the cavitation number by filling it with different depths and hitting

  15. Frontal Tasks and Behavior in Rigid or Tremor-Dominant Parkinson Disease.

    PubMed

    Moretti, Rita; Milner, Vera; Caruso, Paola; Gazzin, Silvia; Rumiati, Raffaella

    2017-08-01

    Parkinson disease (PD) is not an unambiguous entity, and there is a general consensus for the statement that an akinetic-rigid dominant type of presentation has a worse prognosis, in the follow-up. The aim of our study was to examine the differences in frontal tasks and behavior, in 2 PD naive groups: the rigid and the tremor-dominant types of presentation, according to motor scores. Our study has showed some important differences in frontal tasks and in behavior, performing more apathy, aggressiveness, and irritability in the rigid type, and more depression and anxiety in the tremor-dominant type. The former group causes the caregiver more distress and has a very rapid disease progression. It can be argued that rigid type PD presentation needs specific dedicated cares and more strong clinical attention.

  16. Method to estimate center of rigidity using vibration recordings

    USGS Publications Warehouse

    Safak, Erdal; Çelebi, Mehmet

    1990-01-01

    A method to estimate the center of rigidity of buildings by using vibration recordings is presented. The method is based on the criterion that the coherence of translational motions with the rotational motion is minimum at the center of rigidity. Since the coherence is a function of frequency, a gross but frequency-independent measure of the coherency is defined as the integral of the coherence function over the frequency. The center of rigidity is determined by minimizing this integral. The formulation is given for two-dimensional motions. Two examples are presented for the method; a rectangular building with ambient-vibration recordings, and a triangular building with earthquake-vibration recordings. Although the examples given are for buildings, the method can be applied to any structure with two-dimensional motions.

  17. Experimental method for determination of bending and torsional rigidities of advanced composite laminates

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

    Maeda, Takenori

    1995-11-01

    This paper presents an experimental method for the determination of the bending and torsional rigidities of advanced fiber composite laminates with the aid of laser holographic interferometry. The proposed method consists of a four-point bending test and a resonance test. The bending rigidity ratio (D{sub 12}/D{sub 22}) can be determined from the fringe patterns of the four-point bending test. The bending rigidities (D{sub 11} and D{sub 22}) and the torsional rigidity (D{sub 66}) are calculated from the natural frequencies of cantilever plates of the resonance test. The test specimens are carbon/epoxy cross-ply laminates. The adequacy of the experimental method ismore » confirmed by comparing the measured rigidities with the theoretical values obtained from classical lamination theory (CLT) by using the measured tensile properties. The results show that the present method can be used to evaluate the rigidities of orthotropic laminates with reasonably good accuracy.« less

  18. Effect of Heliox on Respiratory Outcomes during Rigid Bronchoscopy in Term Lambs.

    PubMed

    Sowder, Justin C; Dahl, Mar Janna; Zuspan, Kaitlin R; Albertine, Kurt H; Null, Donald M; Barneck, Mitchell D; Grimmer, J Fredrik

    2018-03-01

    Objective To (1) compare physiologic changes during rigid bronchoscopy during spontaneous and mechanical ventilation and (2) evaluate the efficacy of a helium-oxygen (heliox) gas mixture as compared with room air during rigid bronchoscopy. Study Design Crossover animal study evaluating physiologic parameters during rigid bronchoscopy. Outcomes were compared with predicted computational fluid analysis. Setting Simulated ventilation via computational fluid dynamics analysis and term lambs undergoing rigid bronchoscopy. Methods Respiratory and physiologic outcomes were analyzed in a lamb model simulating bronchoscopy during foreign body aspiration to compare heliox with room air. The main outcome measures were blood oxygen saturation, heart rate, blood pressure, partial pressure of oxygen, and partial pressure of carbon dioxide. Computational fluid dynamics analysis was performed with SOLIDWORKS within a rigid pediatric bronchoscope during simulated ventilation comparing heliox with room air. Results For room air, lambs desaturated within 3 minutes during mechanical ventilation versus normal oxygen saturation during spontaneous ventilation ( P = .01). No improvement in respiratory outcomes was seen between heliox and room air during mechanical ventilation. Computational fluid dynamics analysis demonstrates increased turbulence within size 3.5 bronchoscopes when comparing heliox and room air. Meaningful comparisons could not be made due to the intolerance of the lambs to heliox in vivo. Conclusion During mechanical ventilation on room air, lambs desaturate more quickly during rigid bronchoscopy on settings that should be adequate. Heliox does not improve ventilation during rigid bronchoscopy.

  19. Deformable image registration for adaptive radiotherapy with guaranteed local rigidity constraints.

    PubMed

    König, Lars; Derksen, Alexander; Papenberg, Nils; Haas, Benjamin

    2016-09-20

    Deformable image registration (DIR) is a key component in many radiotherapy applications. However, often resulting deformations are not satisfying, since varying deformation properties of different anatomical regions are not considered. To improve the plausibility of DIR in adaptive radiotherapy in the male pelvic area, this work integrates a local rigidity deformation model into a DIR algorithm. A DIR framework is extended by constraints, enforcing locally rigid deformation behavior for arbitrary delineated structures. The approach restricts those structures to rigid deformations, while surrounding tissue is still allowed to deform elastically. The algorithm is tested on ten CT/CBCT male pelvis datasets with active rigidity constraints on bones and prostate and compared to the Varian SmartAdapt deformable registration (VSA) on delineations of bladder, prostate and bones. The approach with no rigid structures (REG0) obtains an average dice similarity coefficient (DSC) of 0.87 ± 0.06 and a Hausdorff-Distance (HD) of 8.74 ± 5.95 mm. The new approach with rigid bones (REG1) yields a DSC of 0.87 ± 0.07, HD 8.91 ± 5.89 mm. Rigid deformation of bones and prostate (REG2) obtains 0.87 ± 0.06, HD 8.73 ± 6.01 mm, while VSA yields a DSC of 0.86 ± 0.07, HD 10.22 ± 6.62 mm. No deformation grid foldings are observed for REG0 and REG1 in 7 of 10 cases; for REG2 in 8 of 10 cases, with no grid foldings in prostate, an average of 0.08 % in bladder (REG2: no foldings) and 0.01 % inside the body contour. VSA exhibits grid foldings in each case, with an average percentage of 1.81 % for prostate, 1.74 % for bladder and 0.12 % for the body contour. While REG1 and REG2 keep bones rigid, elastic bone deformations are observed with REG0 and VSA. An average runtime of 26.2 s was achieved with REG1; 31.1 s with REG2, compared to 10.5 s with REG0 and 10.7 s with VMS. With accuracy in the range of VSA, the new approach with constraints delivers physically more plausible deformations in

  20. 46 CFR 131.860 - Rigid liferafts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., over each entrance to each raft, in letters and numbers at least 102 millimeters (4 inches) high and in a color contrasting to that of the raft. This number must— (1) Be the number of persons the rigid...

  1. Activity-induced collapse and reexpansion of rigid polymers

    NASA Astrophysics Data System (ADS)

    Harder, J.; Valeriani, C.; Cacciuto, A.

    2014-12-01

    We study the elastic properties of a rigid filament in a bath of self-propelled particles. We find that while fully flexible filaments swell monotonically upon increasing the strength of the propelling force, rigid filaments soften for moderate activities, collapse into metastable hairpins for intermediate strengths, and eventually reexpand when the strength of the activity of the surrounding fluid is large. This collapse and reexpansion of the filament with the bath activity is reminiscent of the behavior observed in polyelectrolytes in the presence of different concentrations of multivalent salt.

  2. Coherent states for the quantum complete rigid rotor

    NASA Astrophysics Data System (ADS)

    Fontanari, Daniele; Sadovskií, Dmitrií A.

    2018-07-01

    Motivated by the possibility to describe orientations of quantum triaxial rigid rotors, such as molecules, with respect to both internal (body-fixed) and external (laboratory) frames, we go through the theory of coherent states and design the appropriate family of coherent states on T∗ SO(3) , the classical phase space of the freely rotating rigid body (the Euler top). We pay particular attention to the resolution of identity property in order to establish the explicit relation between the parameters of the coherent states and classical phase-space variables, actions and angles.

  3. A DNA Origami Mechanical Device for the Regulation of Microcosmic Structural Rigidity.

    PubMed

    Wan, Neng; Hong, Zhouping; Wang, Huading; Fu, Xin; Zhang, Ziyue; Li, Chao; Xia, Han; Fang, Yan; Li, Maoteng; Zhan, Yi; Yang, Xiangliang

    2017-11-01

    DNA origami makes it feasible to fabricate a tremendous number of DNA nanostructures with various geometries, dimensions, and functionalities. Moreover, an increasing amount of research on DNA nanostructures is focused on biological and biomedical applications. Here, the reversible regulation of microcosmic structural rigidity is accomplished using a DNA origami device in vitro. The designed DNA origami monomer is composed of an internal central axis and an external sliding tube. Due to the external tube sliding, the device transforms between flexible and rigid states. By transporting the device into the liposome, the conformational change of the origami device induces a structural change in the liposome. The results obtained demonstrate that the programmed DNA origami device can be applied to regulate the microcosmic structural rigidity of liposomes. Because microcosmic structural rigidity is important to cell proliferation and function, the results obtained potentially provide a foundation for the regulation of cell microcosmic structural rigidity using DNA nanostructures. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. The effects of nail rigidity on fracture healing in rats with osteoporosis

    PubMed Central

    Sha, Mo; Fu, Jun; Li, Jing; Fan Yuan, Chao; Shi, Lei; Jun Li, Shu

    2009-01-01

    Background and purpose Stress shielding from rigid internal fixation may lead to refracture after removal of the osteosynthesis material. We investigated the effect of a low-rigidity (Ti-24Nb-4Zr-7.9Sn) intramedullary nail regarding stress shielding and bone healing of osteoporotic fractures in the rat. Methods 40 female Sprague-Dawley rats, aged 3 months, were divided into the following groups: sham-operation (SHAM) (n = 10), ovariectomized (OVX) (n = 10) and OVX-fracture (n = 20). 10 SHAM rats and 10 OVX rats were killed after 12 weeks to provide biomechanical data. Ovariectomy was performed 12 weeks before fracturing both femurs in 20 rats. The left fracture was stabilized with a high-rigidity titanium alloy pin (Ti-6Al-4V; elastic modulus 110 GPa) and the right with a low-rigidity (Ti-24Nb-4Zr-7.9Sn; elastic modulus 33 GPa). The bony calluses were examined by micro-CT at 6 and 12 weeks after fracture, bone volume (BV) and total volume (TV) were determined at the callus region (ROI1) and the total femur (ROI2). Subsequently, the bones were tested mechanically by a three-point bending test. Results In the low-rigidity group, TV (ROI1) increased at 6 weeks, but BV (ROI1), BV (ROI2) were similar but maximum load increased. At 12 weeks, the maximum load and also BV (ROI1, ROI2) were increased in the low-rigidity group. Interpretation The low-rigidity nail manufactured from Ti-24Nb-4Zr-7.9Sn showed better external callus formation, seemed to reduce effects of stress shielding, and reduced bone resorption better than the stiffer nail. The low-rigidity nail was strong enough to maintain alignment of the fracture in the osteoporotic rat model without delayed union. PMID:19297794

  5. Botulinum toxin in myotonia congenita: it does not help against rigidity and pain.

    PubMed

    Dressler, Dirk; Adib Saberi, Fereshte

    2014-05-01

    Botulinum toxin (BT) is a potent local muscle relaxant with analgetic properties. Myotonia congenita (MC) is a genetic disorder producing muscle rigidity and pain. BT injected into the trapezius produced mild paresis, but no effect on rigidity and pain. There were no signs of systemic effects. Lack of BT efficacy on MC rigidity confirms its origin from muscle membrane dysfunction rather than from inappropriate neuromuscular activation. Lack of BT efficacy on pain could be caused by lack of anti-rigidity effect. It could also be due to separate non-muscular pain mechanisms unresponsive to BT.

  6. Calculating ensemble averaged descriptions of protein rigidity without sampling.

    PubMed

    González, Luis C; Wang, Hui; Livesay, Dennis R; Jacobs, Donald J

    2012-01-01

    Previous works have demonstrated that protein rigidity is related to thermodynamic stability, especially under conditions that favor formation of native structure. Mechanical network rigidity properties of a single conformation are efficiently calculated using the integer body-bar Pebble Game (PG) algorithm. However, thermodynamic properties require averaging over many samples from the ensemble of accessible conformations to accurately account for fluctuations in network topology. We have developed a mean field Virtual Pebble Game (VPG) that represents the ensemble of networks by a single effective network. That is, all possible number of distance constraints (or bars) that can form between a pair of rigid bodies is replaced by the average number. The resulting effective network is viewed as having weighted edges, where the weight of an edge quantifies its capacity to absorb degrees of freedom. The VPG is interpreted as a flow problem on this effective network, which eliminates the need to sample. Across a nonredundant dataset of 272 protein structures, we apply the VPG to proteins for the first time. Our results show numerically and visually that the rigidity characterizations of the VPG accurately reflect the ensemble averaged [Formula: see text] properties. This result positions the VPG as an efficient alternative to understand the mechanical role that chemical interactions play in maintaining protein stability.

  7. Characterizations of linear sufficient statistics

    NASA Technical Reports Server (NTRS)

    Peters, B. C., Jr.; Reoner, R.; Decell, H. P., Jr.

    1977-01-01

    A surjective bounded linear operator T from a Banach space X to a Banach space Y must be a sufficient statistic for a dominated family of probability measures defined on the Borel sets of X. These results were applied, so that they characterize linear sufficient statistics for families of the exponential type, including as special cases the Wishart and multivariate normal distributions. The latter result was used to establish precisely which procedures for sampling from a normal population had the property that the sample mean was a sufficient statistic.

  8. Robust non-rigid registration algorithm based on local affine registration

    NASA Astrophysics Data System (ADS)

    Wu, Liyang; Xiong, Lei; Du, Shaoyi; Bi, Duyan; Fang, Ting; Liu, Kun; Wu, Dongpeng

    2018-04-01

    Aiming at the problem that the traditional point set non-rigid registration algorithm has low precision and slow convergence speed for complex local deformation data, this paper proposes a robust non-rigid registration algorithm based on local affine registration. The algorithm uses a hierarchical iterative method to complete the point set non-rigid registration from coarse to fine. In each iteration, the sub data point sets and sub model point sets are divided and the shape control points of each sub point set are updated. Then we use the control point guided affine ICP algorithm to solve the local affine transformation between the corresponding sub point sets. Next, the local affine transformation obtained by the previous step is used to update the sub data point sets and their shape control point sets. When the algorithm reaches the maximum iteration layer K, the loop ends and outputs the updated sub data point sets. Experimental results demonstrate that the accuracy and convergence of our algorithm are greatly improved compared with the traditional point set non-rigid registration algorithms.

  9. Cosmic ray proton spectra at low rigidities

    NASA Technical Reports Server (NTRS)

    Seo, E. S.; Ormes, J. F.; Streitmatter, R. E.; Lloyd-Evans, J.; Jones, W. V.

    1990-01-01

    The cosmic ray proton rigidity spectra have been investigated with data collected in the Low Energy Antiproton (LEAP) balloon flight experiment flown from Prince Albert, Canada in 1987. The LEAP apparatus was designed to measure antiprotons using a superconducting magnet spectrometer with ancillary scintillator, time-of-flight, and liquid Cherenkov detectors. After reaching float altitude the balloon drifted south and west to higher geomagnetic cutoffs. The effect of the changing geomagnetic cutoff on the observed spectra was observed during analysis of the proton data along the balloon trajectory. This is the first measurement of the primary and splash albedo spectra over a wide rigidity range (few hundred MV to about 100 GV) with a single instrument.

  10. SU-E-J-225: Quantitative Evaluation of Rigid and Non-Rigid Motion of Liver Tumors Using Stereo Imaging During SBRT

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

    Xu, Q; Hanna, G; Kubicek, G

    2014-06-01

    Purpose: To quantitatively evaluate rigid and nonrigid motion of liver tumors based on fiducial tracking in 3D by stereo imaging during CyberKnife SBRT. Methods: Twenty-five liver patients previously treated with three-fractions of SBRT were retrospectively recruited in this study. During treatment, the 3D locations of fiducials were reported by the CyberKnife system after two orthogonal kV X-ray images were taken and further validated by geometry derivations. A total of 5004 pairs of X-ray images acquired during the course of treatment for all the patients, were analyzed. For rigid motion, the rotational angles and translational shifts by aligning 3D fiducial groupsmore » in different image pairs after least-square fitting were reported. For nonrigid motion, the relative interfractional tumor shape variations were reported and correlated to the sum of inter-fiducial distances. The individual fiducial displacements were also reported after rigid corrections and without angle corrections. Results: The relative tumor volume variation indicated by the inter-fiducial distances demonstrated an increasing trend in the second (101.6±3.4%) and third fraction (101.2±5.6%) among most patients. The cause could be possibly due to radiation-induced edema. For all the patients, the translational shift was 8.1±5.7 mm, with shifts in LR, AP and SI were 2.1±2.4 mm, 2.8±2.9 mm and 6.7±5.1 mm, respectively. The greatest translation shift occurred in SI, mainly due the breathing motion of diaphragm The rotational angles were 1.1±1.7°, 1.9±2.6° and 1.6±2.2°, in roll, pitch, and yaw, respectively. The 3D fiducial displacement with rigid corrections were 0.2±0.2 mm and increased to 0.6±0.3 mm without rotational corrections. Conclusion: The fiducial locations in 3D can be precisely reconstructed from CyberKnife stereo imaging system during treatment. The fiducials provide close estimation of both rigid and nonrigid motion of .liver tumors. The reported data could be

  11. Flow properties and hydrodynamic interactions of rigid spherical microswimmers

    NASA Astrophysics Data System (ADS)

    Adhyapak, Tapan Chandra; Jabbari-Farouji, Sara

    2017-11-01

    We analyze a minimal model for a rigid spherical microswimmer and explore the consequences of its extended surface on the interplay between its self-propulsion and flow properties. The model is the first order representation of microswimmers, such as bacteria and algae, with rigid bodies and flexible propelling appendages. The flow field of such a microswimmer at finite distances significantly differs from that of a point-force (Stokeslet) dipole. For a suspension of microswimmers, we derive the grand mobility matrix that connects the motion of an individual swimmer to the active and passive forces and torques acting on all the swimmers. Our investigation of the mobility tensors reveals that hydrodynamic interactions among rigid-bodied microswimmers differ considerably from those among the corresponding point-force dipoles. Our results are relevant for the study of collective behavior of hydrodynamically interacting microswimmers by means of Stokesian dynamics simulations at moderate concentrations.

  12. Matrix Rigidity Regulates Cancer Cell Growth and Cellular Phenotype

    PubMed Central

    Tilghman, Robert W.; Cowan, Catharine R.; Mih, Justin D.; Koryakina, Yulia; Gioeli, Daniel; Slack-Davis, Jill K.; Blackman, Brett R.; Tschumperlin, Daniel J.; Parsons, J. Thomas

    2010-01-01

    Background The mechanical properties of the extracellular matrix have an important role in cell growth and differentiation. However, it is unclear as to what extent cancer cells respond to changes in the mechanical properties (rigidity/stiffness) of the microenvironment and how this response varies among cancer cell lines. Methodology/Principal Findings In this study we used a recently developed 96-well plate system that arrays extracellular matrix-conjugated polyacrylamide gels that increase in stiffness by at least 50-fold across the plate. This plate was used to determine how changes in the rigidity of the extracellular matrix modulate the biological properties of tumor cells. The cell lines tested fall into one of two categories based on their proliferation on substrates of differing stiffness: “rigidity dependent” (those which show an increase in cell growth as extracellular rigidity is increased), and “rigidity independent” (those which grow equally on both soft and stiff substrates). Cells which grew poorly on soft gels also showed decreased spreading and migration under these conditions. More importantly, seeding the cell lines into the lungs of nude mice revealed that the ability of cells to grow on soft gels in vitro correlated with their ability to grow in a soft tissue environment in vivo. The lung carcinoma line A549 responded to culture on soft gels by expressing the differentiated epithelial marker E-cadherin and decreasing the expression of the mesenchymal transcription factor Slug. Conclusions/Significance These observations suggest that the mechanical properties of the matrix environment play a significant role in regulating the proliferation and the morphological properties of cancer cells. Further, the multiwell format of the soft-plate assay is a useful and effective adjunct to established 3-dimensional cell culture models. PMID:20886123

  13. Brownian dynamics of confined rigid bodies

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

    Delong, Steven; Balboa Usabiaga, Florencio; Donev, Aleksandar, E-mail: donev@courant.nyu.edu

    2015-10-14

    We introduce numerical methods for simulating the diffusive motion of rigid bodies of arbitrary shape immersed in a viscous fluid. We parameterize the orientation of the bodies using normalized quaternions, which are numerically robust, space efficient, and easy to accumulate. We construct a system of overdamped Langevin equations in the quaternion representation that accounts for hydrodynamic effects, preserves the unit-norm constraint on the quaternion, and is time reversible with respect to the Gibbs-Boltzmann distribution at equilibrium. We introduce two schemes for temporal integration of the overdamped Langevin equations of motion, one based on the Fixman midpoint method and the othermore » based on a random finite difference approach, both of which ensure that the correct stochastic drift term is captured in a computationally efficient way. We study several examples of rigid colloidal particles diffusing near a no-slip boundary and demonstrate the importance of the choice of tracking point on the measured translational mean square displacement (MSD). We examine the average short-time as well as the long-time quasi-two-dimensional diffusion coefficient of a rigid particle sedimented near a bottom wall due to gravity. For several particle shapes, we find a choice of tracking point that makes the MSD essentially linear with time, allowing us to estimate the long-time diffusion coefficient efficiently using a Monte Carlo method. However, in general, such a special choice of tracking point does not exist, and numerical techniques for simulating long trajectories, such as the ones we introduce here, are necessary to study diffusion on long time scales.« less

  14. Apparatus for integrating a rigid structure into a flexible wall of an inflatable structure

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J. (Inventor); Patterson, Ross M. (Inventor); Spexarth, Gary R. (Inventor)

    2009-01-01

    For an inflatable structure having a flexible outer shell or wall structure having a flexible restraint layer comprising interwoven, load-bearing straps, apparatus for integrating one or more substantially rigid members into the flexible shell. For each rigid member, a corresponding opening is formed through the flexible shell for receiving the rigid member. A plurality of connection devices are mounted on the rigid member for receiving respective ones of the load-bearing straps. In one embodiment, the connection devices comprise inner connecting mechanisms and outer connecting mechanisms, the inner and outer connecting mechanisms being mounted on the substantially rigid structure and spaced along a peripheral edge portion of the structure in an interleafed array in which respective outer connecting mechanisms are interposed between adjacent pairs of inner connecting mechanisms, the outer connecting mechanisms projecting outwardly from the peripheral edge portion of the substantially rigid structure beyond the adjacent inner connecting mechanisms to form a staggered array of connecting mechanisms extending along the panel structure edge portion. In one embodiment, the inner and outer connecting mechanisms form part of an integrated, structure rotatably mounted on the rigid member peripheral edge portion.

  15. Non-rigid Reconstruction of Casting Process with Temperature Feature

    NASA Astrophysics Data System (ADS)

    Lin, Jinhua; Wang, Yanjie; Li, Xin; Wang, Ying; Wang, Lu

    2017-09-01

    Off-line reconstruction of rigid scene has made a great progress in the past decade. However, the on-line reconstruction of non-rigid scene is still a very challenging task. The casting process is a non-rigid reconstruction problem, it is a high-dynamic molding process lacking of geometric features. In order to reconstruct the casting process robustly, an on-line fusion strategy is proposed for dynamic reconstruction of casting process. Firstly, the geometric and flowing feature of casting are parameterized in manner of TSDF (truncated signed distance field) which is a volumetric block, parameterized casting guarantees real-time tracking and optimal deformation of casting process. Secondly, data structure of the volume grid is extended to have temperature value, the temperature interpolation function is build to generate the temperature of each voxel. This data structure allows for dynamic tracking of temperature of casting during deformation stages. Then, the sparse RGB features is extracted from casting scene to search correspondence between geometric representation and depth constraint. The extracted color data guarantees robust tracking of flowing motion of casting. Finally, the optimal deformation of the target space is transformed into a nonlinear regular variational optimization problem. This optimization step achieves smooth and optimal deformation of casting process. The experimental results show that the proposed method can reconstruct the casting process robustly and reduce drift in the process of non-rigid reconstruction of casting.

  16. Extracting a Purely Non-rigid Deformation Field of a Single Structure

    NASA Astrophysics Data System (ADS)

    Demirci, Stefanie; Manstad-Hulaas, Frode; Navab, Nassir

    During endovascular aortic repair (EVAR) treatment, the aortic shape is subject to severe deformation that is imposed by medical instruments such as guide wires, catheters, and the stent graft. The problem definition of deformable registration of images covering the entire abdominal region, however, is highly ill-posed. We present a new method for extracting the deformation of an aneurysmatic aorta. The outline of the procedure includes initial rigid alignment of two abdominal scans, segmentation of abdominal vessel trees, and automatic reduction of their centerline structures to one specified region of interest around the aorta. Our non-rigid registration procedure then only computes local non-rigid deformation and leaves out all remaining global rigid transformations. In order to evaluate our method, experiments for the extraction of aortic deformation fields are conducted on 15 patient datasets from endovascular aortic repair (EVAR) treatment. A visual assessment of the registration results were performed by two vascular surgeons and one interventional radiologist who are all experts in EVAR procedures.

  17. Method for identification of rigid domains and hinge residues in proteins based on exhaustive enumeration.

    PubMed

    Sim, Jaehyun; Sim, Jun; Park, Eunsung; Lee, Julian

    2015-06-01

    Many proteins undergo large-scale motions where relatively rigid domains move against each other. The identification of rigid domains, as well as the hinge residues important for their relative movements, is important for various applications including flexible docking simulations. In this work, we develop a method for protein rigid domain identification based on an exhaustive enumeration of maximal rigid domains, the rigid domains not fully contained within other domains. The computation is performed by mapping the problem to that of finding maximal cliques in a graph. A minimal set of rigid domains are then selected, which cover most of the protein with minimal overlap. In contrast to the results of existing methods that partition a protein into non-overlapping domains using approximate algorithms, the rigid domains obtained from exact enumeration naturally contain overlapping regions, which correspond to the hinges of the inter-domain bending motion. The performance of the algorithm is demonstrated on several proteins. © 2015 Wiley Periodicals, Inc.

  18. The Estimation of a Rigid Body Motion in the Presence of Noise.

    DTIC Science & Technology

    1987-07-31

    Rigid Body Motion in the Presence of Noise 12. PERSONAL AUTHOR(S) 1S. AYOFDREPRTy 13b.e ad COVRE C4. 10AOUTE OF FUNPING NUBERSlAE...8217, .,_, .,,.. .\\ ..: ., : ’ *-: ,:,.,,. .’ 4 /. .’.’ ’, ’ ,. 9) 7 TRACT The problem of estimating a rigid body motion from two noisy images of an...SI ... ... Cs . I ,-’ ’".’ 1 -, ED 1, D:;.;i,1q L HARVARD UNIVERSITY DzPAILTMNT OP STATIMCS THE ESTIMATION OF A RIGID BODY MOTION IN THE

  19. Rigid bronchoscopy and silicone stents in the management of central airway obstruction

    PubMed Central

    Yarmus, Lonny

    2015-01-01

    The field of interventional pulmonology has grown significantly over the past several decades now including the diagnosis and therapeutic treatment of complex airway disease. Rigid bronchoscopy is an invaluable tool in the diagnosis and management of several malignant and non-malignant causes of central airway obstruction (CAO) and has become integral after the inception of airway stenting. The management of CAO can be a complicated endeavor with significant risks making the understanding of basic rigid bronchoscopy techniques, ablative technologies, anesthetic care and stenting of utmost importance in the care of these complex patients. This review article will focus on the history of rigid bronchoscopy, the technical aspects of performing a rigid bronchoscopy as well as the use of silicone stents their indications, complications and placement techniques. PMID:26807283

  20. Rigid porous filter

    DOEpatents

    Chiang, Ta-Kuan; Straub, Douglas L.; Dennis, Richard A.

    2000-01-01

    The present invention involves a porous rigid filter including a plurality of concentric filtration elements having internal flow passages and forming external flow passages there between. The present invention also involves a pressure vessel containing the filter for the removal of particulates from high pressure particulate containing gases, and further involves a method for using the filter to remove such particulates. The present filter has the advantage of requiring fewer filter elements due to the high surface area-to-volume ratio provided by the filter, requires a reduced pressure vessel size, and exhibits enhanced mechanical design properties, improved cleaning properties, configuration options, modularity and ease of fabrication.

  1. The effect of rigid and non-rigid connections between implants and teeth on biological and technical complications: a systematic review and a meta-analysis.

    PubMed

    Tsaousoglou, Phoebus; Michalakis, Konstantinos; Kang, Kiho; Weber, Hans-Peter; Sculean, Anton

    2017-07-01

    To assess survival, as well as technical and biological complication rates of partial fixed dental prostheses (FDPs) supported by implants and teeth. An electronic Medline search was conducted to identify articles, published in dental journals from January 1980 to August 2015, reporting on partial FDPs supported by implants and teeth. The search terms were categorized into four groups comprising the PICO question. Manual searches of published full-text articles and related reviews were also performed. The initial database search produced 3587 relevant titles. Three hundred and eighty-six articles were retrieved for abstract review, while 39 articles were selected for full-text review. A total of 10 studies were selected for inclusion. Overall survival rate for implants ranged between 90% and 100%, after follow-up periods with a mean range of 18-120 months. The survival of the abutment teeth was 94.1-100%, while the prostheses survival was 85-100% for the same time period. The most frequent complications were "periapical lesions" (11.53%). The most frequent technical complication was "porcelain occlusal fracture" (16.6%), followed by "screw loosening" (15%). According to the meta-analysis, no intrusion was noted on the rigid connection group, while five teeth (8.19%) were intruded in the non-rigid connection group [95% CI (0.013-0.151)]. The tooth-implant FDP seems to be a possible alternative to an implant-supported FDP. There is limited evidence that rigid connection between teeth and implants presents better results when compared with the non-rigid one. The major drawback of non-rigidly connected FDPs is tooth intrusion. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. NoRMCorre: An online algorithm for piecewise rigid motion correction of calcium imaging data.

    PubMed

    Pnevmatikakis, Eftychios A; Giovannucci, Andrea

    2017-11-01

    Motion correction is a challenging pre-processing problem that arises early in the analysis pipeline of calcium imaging data sequences. The motion artifacts in two-photon microscopy recordings can be non-rigid, arising from the finite time of raster scanning and non-uniform deformations of the brain medium. We introduce an algorithm for fast Non-Rigid Motion Correction (NoRMCorre) based on template matching. NoRMCorre operates by splitting the field of view (FOV) into overlapping spatial patches along all directions. The patches are registered at a sub-pixel resolution for rigid translation against a regularly updated template. The estimated alignments are subsequently up-sampled to create a smooth motion field for each frame that can efficiently approximate non-rigid artifacts in a piecewise-rigid manner. Existing approaches either do not scale well in terms of computational performance or are targeted to non-rigid artifacts arising just from the finite speed of raster scanning, and thus cannot correct for non-rigid motion observable in datasets from a large FOV. NoRMCorre can be run in an online mode resulting in comparable to or even faster than real time motion registration of streaming data. We evaluate its performance with simple yet intuitive metrics and compare against other non-rigid registration methods on simulated data and in vivo two-photon calcium imaging datasets. Open source Matlab and Python code is also made available. The proposed method and accompanying code can be useful for solving large scale image registration problems in calcium imaging, especially in the presence of non-rigid deformations. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

  3. Pressure-release versus rigid reflector for extracorporeal shockwave lithotripsy.

    PubMed

    Loske, Achim M; Prieto, Fernando E

    2002-06-01

    To evaluate the advantages and disadvantages of using a pressure-release reflector instead of a rigid reflector to concentrate shockwaves for extracorporeal shockwave lithotripsy (SWL). As in all electrohydraulic lithotripters, shockwaves were generated by electrical breakdown of water between two electrodes, located at the focus (F1) closest to a paraellipsoidal reflector. A pressure-release reflector, made out of polyurethane foam, was constructed and tested on a research lithotripter using kidney stone models. Fragmentation data and pressure measurements were compared with those of a conventional rigid reflector tested on the same device. The weight of stone model fragments remaining after shockwave exposure was less with the pressure-release reflector after screening through a 3.0 x 3.0-mm mesh. The residual fragment weight was less with the rigid reflector using 1.0 x 1.0- and 0.6 x 0.6-mm meshes. Pressure-release reflectors may maintain acceptable stone fragmentation while offering improved patient safety and should be considered for SWL.

  4. Dimensional Metrology of Non-rigid Parts Without Specialized Inspection Fixtures =

    NASA Astrophysics Data System (ADS)

    Sabri, Vahid

    Quality control is an important factor for manufacturing companies looking to prosper in an era of globalization, market pressures and technological advances. Functionality and product quality cannot be guaranteed without this important aspect. Manufactured parts have deviations from their nominal (CAD) shape caused by the manufacturing process. Thus, geometric inspection is a very important element in the quality control of mechanical parts. We will focus here on the geometric inspection of non-rigid (flexible) parts which are widely used in the aeronautic and automotive industries. Non-rigid parts can have different forms in a free-state condition compared with their nominal models due to residual stress and gravity loads. To solve this problem, dedicated inspection fixtures are generally used in industry to compensate for the displacement of such parts for simulating the use state in order to perform geometric inspections. These fixtures and the installation and inspection processes are expensive and time-consuming. Our aim in this thesis is therefore to develop an inspection method which eliminates the need for specialized fixtures. This is done by acquiring a point cloud from the part in a free-state condition using a contactless measuring device such as optical scanning and comparing it with the CAD model for the deviation identification. Using a non-rigid registration method and finite element analysis, we numerically inspect the profile of a non-rigid part. To do so, a simulated displacement is performed using an improved definition of displacement boundary conditions for simulating unfixed parts. In addition, we propose a numerical method for dimensional metrology of non-rigid parts in a free-state condition based on the arc length measurement by calculating the geodesic distance using the Fast Marching Method (FMM). In this thesis, we apply our developed methods on industrial non-rigid parts with free-form surfaces simulated with different types of

  5. Multiscale multiphysics and multidomain models—Flexibility and rigidity

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

    Xia, Kelin; Opron, Kristopher; Wei, Guo-Wei, E-mail: wei@math.msu.edu

    The emerging complexity of large macromolecules has led to challenges in their full scale theoretical description and computer simulation. Multiscale multiphysics and multidomain models have been introduced to reduce the number of degrees of freedom while maintaining modeling accuracy and achieving computational efficiency. A total energy functional is constructed to put energies for polar and nonpolar solvation, chemical potential, fluid flow, molecular mechanics, and elastic dynamics on an equal footing. The variational principle is utilized to derive coupled governing equations for the above mentioned multiphysical descriptions. Among these governing equations is the Poisson-Boltzmann equation which describes continuum electrostatics with atomicmore » charges. The present work introduces the theory of continuum elasticity with atomic rigidity (CEWAR). The essence of CEWAR is to formulate the shear modulus as a continuous function of atomic rigidity. As a result, the dynamics complexity of a macromolecular system is separated from its static complexity so that the more time-consuming dynamics is handled with continuum elasticity theory, while the less time-consuming static analysis is pursued with atomic approaches. We propose a simple method, flexibility-rigidity index (FRI), to analyze macromolecular flexibility and rigidity in atomic detail. The construction of FRI relies on the fundamental assumption that protein functions, such as flexibility, rigidity, and energy, are entirely determined by the structure of the protein and its environment, although the structure is in turn determined by all the interactions. As such, the FRI measures the topological connectivity of protein atoms or residues and characterizes the geometric compactness of the protein structure. As a consequence, the FRI does not resort to the interaction Hamiltonian and bypasses matrix diagonalization, which underpins most other flexibility analysis methods. FRI's computational complexity

  6. Damping of quasi-two-dimensional internal wave attractors by rigid-wall friction

    NASA Astrophysics Data System (ADS)

    Beckebanze, F.; Brouzet, C.; Sibgatullin, I. N.; Maas, L. R. M.

    2018-04-01

    The reflection of internal gravity waves at sloping boundaries leads to focusing or defocusing. In closed domains, focusing typically dominates and projects the wave energy onto 'wave attractors'. For small-amplitude internal waves, the projection of energy onto higher wave numbers by geometric focusing can be balanced by viscous dissipation at high wave numbers. Contrary to what was previously suggested, viscous dissipation in interior shear layers may not be sufficient to explain the experiments on wave attractors in the classical quasi-2D trapezoidal laboratory set-ups. Applying standard boundary layer theory, we provide an elaborate description of the viscous dissipation in the interior shear layer, as well as at the rigid boundaries. Our analysis shows that even if the thin lateral Stokes boundary layers consist of no more than 1% of the wall-to-wall distance, dissipation by lateral walls dominates at intermediate wave numbers. Our extended model for the spectrum of 3D wave attractors in equilibrium closes the gap between observations and theory by Hazewinkel et al. (2008).

  7. The influence of joint rigidity on impact efficiency and ball velocity in football kicking.

    PubMed

    Peacock, James C A; Ball, Kevin

    2018-04-11

    Executing any skill with efficiency is important for performance. In football kicking, conflicting and non-significant results have existed between reducing ankle plantarflexion during foot-ball contact with impact efficiency, making it unclear as to its importance as a coaching instruction. The aims of this study were to first validate a mechanical kicking machine with a non-rigid ankle, and secondly compare a rigid to a non-rigid ankle during the impact phase of football kicking. Measures of foot-ball contact for ten trials per ankle configuration were calculated from data recorded at 4000 Hz and compared. The non-rigid ankle was characterised by initial dorsiflexion followed by plantarflexion for the remainder of impact, and based on similarities to punt and instep kicking, was considered valid. Impact efficiency (foot-to-ball speed ratio) was greater for the rigid ankle (rigid = 1.16 ± 0.02; non-rigid = 1.10 ± 0.01; p < 0.001). The rigid ankle was characterised by significantly greater effective mass and significantly less energy losses. Increasing rigidity allowed a greater portion of mass from the shank to be used during the collision. As the ankle remained in plantarflexion at impact end, stored elastic energy was not converted to ball velocity and was considered lost. Increasing rigidity is beneficial for increasing impact efficiency, and therefore ball velocity. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. A rigid and weathered ice shell on Titan.

    PubMed

    Hemingway, D; Nimmo, F; Zebker, H; Iess, L

    2013-08-29

    Several lines of evidence suggest that Saturn's largest moon, Titan, has a global subsurface ocean beneath an outer ice shell 50 to 200 kilometres thick. If convection is occurring, the rigid portion of the shell is expected to be thin; similarly, a weak, isostatically compensated shell has been proposed to explain the observed topography. Here we report a strong inverse correlation between gravity and topography at long wavelengths that are not dominated by tides and rotation. We argue that negative gravity anomalies (mass deficits) produced by crustal thickening at the base of the ice shell overwhelm positive gravity anomalies (mass excesses) produced by the small surface topography, giving rise to this inverse correlation. We show that this situation requires a substantially rigid ice shell with an elastic thickness exceeding 40 kilometres, and hundreds of metres of surface erosion and deposition, consistent with recent estimates from local features. Our results are therefore not compatible with a geologically active, low-rigidity ice shell. After extrapolating to wavelengths that are controlled by tides and rotation, we suggest that Titan's moment of inertia may be even higher (that is, Titan may be even less centrally condensed) than is currently thought.

  9. Learning intervention-induced deformations for non-rigid MR-CT registration and electrode localization in epilepsy patients

    PubMed Central

    Onofrey, John A.; Staib, Lawrence H.; Papademetris, Xenophon

    2015-01-01

    This paper describes a framework for learning a statistical model of non-rigid deformations induced by interventional procedures. We make use of this learned model to perform constrained non-rigid registration of pre-procedural and post-procedural imaging. We demonstrate results applying this framework to non-rigidly register post-surgical computed tomography (CT) brain images to pre-surgical magnetic resonance images (MRIs) of epilepsy patients who had intra-cranial electroencephalography electrodes surgically implanted. Deformations caused by this surgical procedure, imaging artifacts caused by the electrodes, and the use of multi-modal imaging data make non-rigid registration challenging. Our results show that the use of our proposed framework to constrain the non-rigid registration process results in significantly improved and more robust registration performance compared to using standard rigid and non-rigid registration methods. PMID:26900569

  10. The Influence of Mechanical Parameters on Dielectric Characteristics of Rigid Electrical Insulating Materials

    NASA Astrophysics Data System (ADS)

    Buică, G.; Antonov, A. E.; Beiu, C.; Dobra, R.; Risteiu, M.

    2018-06-01

    Rigid electrical insulating materials are used in the manufacture of work equipment with electric safety function, being mainly intended for use in the energy sector. The paper presents the results of the research on the identification of the technical and safety requirements for rigid electrical insulating materials that are part of the electrical insulating work equipment. The paper aims to show the behaviour of rigid electrical insulating materials under the influence of mechanical risk factors, in order to check the functionality and to ensure the safety function for the entire life time. There were tested rigid electrical insulating equipment designed to be used as safety means in electrical power stations and overhead power lines.

  11. Small Intestinal Submucosa Plug for Closure of Dilated Nephrostomy Tracts: A Pilot Study in Swine

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

    Kakizawa, Hideyaki; Conlin, M. J.; Pavcnik, Dusan, E-mail: pavcnikd@ohsu.edu

    2010-06-15

    The aim of this study was to evaluate efficacy of a plug made of small intestinal submucosa (SIS) for closure of dilated nephrostomy tract in the kidney after nephroscopy. Ten kidneys in 5 swine had nephrostomy tracts dilated up to 8 mm. The SIS plug was placed into the dilated renal cortex under nephroscopic control. Follow-up arteriograms, retrograde pyelograms, and macroscopic and histologic studies at 24 h (n = 4), 6 weeks (n = 2), and 3 months (n = 4) were performed to evaluate the efficacy of the plug. The SIS plug effectively closed the dilated nephrostomy tract. Follow-upmore » studies showed minimal changes of the kidneys, except for 1 small infarction, regarding inflammatory and foreign-body reactions and progressive scarring of the SIS. SIS plug is effective for occlusion of dilated nephrostomy tract after nephroscopy. Its efficacy should be compared with other therapeutic options.« less

  12. The effects of rigid motions on elastic network model force constants

    PubMed Central

    Lezon, Timothy R.

    2012-01-01

    Elastic network models provide an efficient way to quickly calculate protein global dynamics from experimentally determined structures. The model’s single parameter, its force constant, determines the physical extent of equilibrium fluctuations. The values of force constants can be calculated by fitting to experimental data, but the results depend on the type of experimental data used. Here we investigate the differences between calculated values of force constants _t to data from NMR and X-ray structures. We find that X-ray B factors carry the signature of rigid-body motions, to the extent that B factors can be almost entirely accounted for by rigid motions alone. When fitting to more refined anisotropic temperature factors, the contributions of rigid motions are significantly reduced, indicating that the large contribution of rigid motions to B factors is a result of over-fitting. No correlation is found between force constants fit to NMR data and those fit to X-ray data, possibly due to the inability of NMR data to accurately capture protein dynamics. PMID:22228562

  13. The effects of rigid motions on elastic network model force constants.

    PubMed

    Lezon, Timothy R

    2012-04-01

    Elastic network models provide an efficient way to quickly calculate protein global dynamics from experimentally determined structures. The model's single parameter, its force constant, determines the physical extent of equilibrium fluctuations. The values of force constants can be calculated by fitting to experimental data, but the results depend on the type of experimental data used. Here, we investigate the differences between calculated values of force constants and data from NMR and X-ray structures. We find that X-ray B factors carry the signature of rigid-body motions, to the extent that B factors can be almost entirely accounted for by rigid motions alone. When fitting to more refined anisotropic temperature factors, the contributions of rigid motions are significantly reduced, indicating that the large contribution of rigid motions to B factors is a result of over-fitting. No correlation is found between force constants fit to NMR data and those fit to X-ray data, possibly due to the inability of NMR data to accurately capture protein dynamics. Copyright © 2011 Wiley Periodicals, Inc.

  14. Deployment, Foam Rigidization, and Structural Characterization of Inflatable Thin-Film Booms

    NASA Technical Reports Server (NTRS)

    Schnell, Andrew R.; Leigh, Larry M., Jr.; Tinker, Michael L.; McConnaughey, Paul R. (Technical Monitor)

    2002-01-01

    Detailed investigation of the construction, packaging/deployment, foam rigidization, and structural characterization of polyimide film inflatable booms is described. These structures have considerable potential for use in space with solar concentrators, solar sails, space power systems including solar arrays, and other future missions. Numerous thin-film booms or struts were successfully constructed, inflated, injected with foam, and rigidized. Both solid-section and annular test articles were fabricated, using Kapton polyimide film, various adhesives, Styrofoam end plugs, and polyurethane pressurized foam. Numerous inflation/deployment experiments were conducted and compared to computer simulations using the MSC/DYTRAN code. Finite element models were developed for several foam-rigidized struts and compared to model test results. Several problems encountered in the construction, deployment, and foam injection/rigidization process are described. Areas of difficulty included inadequate adhesive strength, cracking of the film arid leakage, excessive bending of the structure during deployment, problems with foam distribution and curing properties, and control of foam leakage following injection into the structure. Many of these problems were overcome in the course of the research.

  15. Structures of mesophilic and extremophilic citrate synthases reveal rigidity and flexibility for function.

    PubMed

    Wells, Stephen A; Crennell, Susan J; Danson, Michael J

    2014-10-01

    Citrate synthase (CS) catalyses the entry of carbon into the citric acid cycle and is highly-conserved structurally across the tree of life. Crystal structures of dimeric CSs are known in both "open" and "closed" forms, which differ by a substantial domain motion that closes the substrate-binding clefts. We explore both the static rigidity and the dynamic flexibility of CS structures from mesophilic and extremophilic organisms from all three evolutionary domains. The computational expense of this wide-ranging exploration is kept to a minimum by the use of rigidity analysis and rapid all-atom simulations of flexible motion, combining geometric simulation and elastic network modeling. CS structures from thermophiles display increased structural rigidity compared with the mesophilic enzyme. A CS structure from a psychrophile, stabilized by strong ionic interactions, appears to display likewise increased rigidity in conventional rigidity analysis; however, a novel modified analysis, taking into account the weakening of the hydrophobic effect at low temperatures, shows a more appropriate decreased rigidity. These rigidity variations do not, however, affect the character of the flexible dynamics, which are well conserved across all the structures studied. Simulation trajectories not only duplicate the crystallographically observed symmetric open-to-closed transitions, but also identify motions describing a previously unidentified antisymmetric functional motion. This antisymmetric motion would not be directly observed in crystallography but is revealed as an intrinsic property of the CS structure by modeling of flexible motion. This suggests that the functional motion closing the binding clefts in CS may be independent rather than symmetric and cooperative. © 2014 Wiley Periodicals, Inc.

  16. Topology-Preserving Rigid Transformation of 2D Digital Images.

    PubMed

    Ngo, Phuc; Passat, Nicolas; Kenmochi, Yukiko; Talbot, Hugues

    2014-02-01

    We provide conditions under which 2D digital images preserve their topological properties under rigid transformations. We consider the two most common digital topology models, namely dual adjacency and well-composedness. This paper leads to the proposal of optimal preprocessing strategies that ensure the topological invariance of images under arbitrary rigid transformations. These results and methods are proved to be valid for various kinds of images (binary, gray-level, label), thus providing generic and efficient tools, which can be used in particular in the context of image registration and warping.

  17. Aerial ultrasound source with a circular vibrating plate attached to a rigid circumferential wall

    NASA Astrophysics Data System (ADS)

    Kuratomi, Ryo; Asami, Takuya; Miura, Hikaru

    2018-07-01

    We fabricate a transverse vibrating plate attached to a rigid wall integrated at the circumference of a circular vibrating plate that allows a strong sound wave field to be formed in the area encoded by the vibrating plate and rigid wall by installing a wall such as a reflective plate on the rigid wall. The design method for the circular vibrating plate attached to a rigid circumferential wall is investigated. A method of forming a strong standing wave field in an enclosed area constructed with a vibrating plate, cylindrical reflective plate, and parallel reflective plate is developed.

  18. Emotional rigidity negatively impacts remission from anxiety and recovery of well-being.

    PubMed

    Wiltgen, Anika; Shepard, Christopher; Smith, Ryan; Fowler, J Christopher

    2018-08-15

    Emotional rigidity is described in clinical literature as a significant barrier to recovery; however, few there are few empirical measures of the construct. The current study had two aims: Study 1 aimed to identify latent factors that may bear on the construct of emotional rigidity while Study 2 assessed the potential impact of the latent factor(s) on anxiety remission rates and well-being. This study utilized data from 2472 adult inpatients (1176 females and 1296 males) with severe psychopathology. Study 1 utilized exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) to identify latent factors of emotional rigidity. Study 2 utilized hierarchical logistic regression analyses to assess the relationships among emotional rigidity factors and anxiety remission and well-being recovery at discharge. Study 1 yielded a two-factor solution identified in EFA was confirmed with CFA. Factor 1 consisted of neuroticism, experiential avoidance, non-acceptance of emotions, impaired goal-directed behavior, impulse control difficulties and limited access to emotion regulation strategies when experiencing negative emotions. Factor 2 consisted of lack of emotional awareness and lack of emotional clarity when experiencing negative emotions. Results of Study 2 indicated higher scores on Factor 1 was associated with lower remission rates from anxiety and poorer well-being upon discharge. Factor 2 was not predictive of outcome. Emotional rigidity appears to be a latent construct that negatively impacts remission rates from anxiety. Limitations of the present study include its retrospective design, and inefficient methods of assessing emotional rigidity. Copyright © 2018. Published by Elsevier B.V.

  19. Flow dynamics in pediatric rigid bronchoscopes using computer-aided design modeling software.

    PubMed

    Barneck, Mitchell D; Webb, J Taylor; Robinson, Ryan E; Grimmer, J Fredrik

    2016-08-01

    Observed complications during rigid bronchoscopy, including hypercarbia and hypoxemia, prompted us to assess how well rigid bronchoscopes serve as an airway device. We performed computer-aided design flow analysis of pediatric rigid bronchoscopes to gain insight into flow dynamics. We made accurate three-dimensional computer models of pediatric rigid bronchoscopes and endotracheal tubes. SOLIDWORKS (Dassault Systemes, Vélizy-Villacoublay, France) flow analysis software was used to analyze fluid dynamics during pressure-controlled and volume-controlled ventilation. Flow analysis was performed on rigid bronchoscopes and similar outer diameter endotracheal tubes comparing resistance, flow, and turbulence during two ventilation modalities and in common surgical scenarios. Increased turbulent flow was observed in bronchoscopes compared to more laminar flow in endotracheal tubes of similar outer diameter. Flow analysis displayed higher resistances in all pediatric bronchoscope sizes except one (3.0 bronchoscope) compared to similar-sized endotracheal tubes. Loss of adequate ventilation was observed if the bronchoscope was not assembled correctly or if increased peak inspiratory pressures were needed. Anesthesia flow to the patient was reduced by 63% during telescope insertion. Flow analysis illustrates increased turbulent flow and increased airflow resistance in all but one size of pediatric bronchoscopes compared to endotracheal tubes. This increased turbulence and resistance, along with the unanticipated gas distal exit pattern, may contribute to the documented hypercarbia and hypoxemia during procedures. These findings may explain why hypoxemia and hypercarbia are commonly observed during rigid bronchoscopy, especially when positive pressure ventilation is needed. NA Laryngoscope, 126:1940-1945, 2016. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

  20. Modeling the Flexural Rigidity of Rod Photoreceptors

    PubMed Central

    Haeri, Mohammad; Knox, Barry E.; Ahmadi, Aphrodite

    2013-01-01

    In vertebrate eyes, the rod photoreceptor has a modified cilium with an extended cylindrical structure specialized for phototransduction called the outer segment (OS). The OS has numerous stacked membrane disks and can bend or break when subjected to mechanical forces. The OS exhibits axial structural variation, with extended bands composed of a few hundred membrane disks whose thickness is diurnally modulated. Using high-resolution confocal microscopy, we have observed OS flexing and disruption in live transgenic Xenopus rods. Based on the experimental observations, we introduce a coarse-grained model of OS mechanical rigidity using elasticity theory, representing the axial OS banding explicitly via a spring-bead model. We calculate a bending stiffness of ∼105 nN⋅μm2, which is seven orders-of-magnitude larger than that of typical cilia and flagella. This bending stiffness has a quadratic relation to OS radius, so that thinner OS have lower fragility. Furthermore, we find that increasing the spatial frequency of axial OS banding decreases OS rigidity, reducing its fragility. Moreover, the model predicts a tendency for OS to break in bands with higher spring number density, analogous to the experimental observation that transgenic rods tended to break preferentially in bands of high fluorescence. We discuss how pathological alterations of disk membrane properties by mutant proteins may lead to increased OS rigidity and thus increased breakage, ultimately contributing to retinal degeneration. PMID:23442852

  1. The role of rigid vs. dynamic instrumentation for stabilization of the degenerative lumbosacral spine.

    PubMed

    Korovessis, Panagiotis; Papazisis, Zisis; Lambiris, Elias

    2002-01-01

    This is a prospective comparative randomised study to compare the immediately postoperative effects of a rigid versus dynamic instrumentation for degenerative spine disease and stenosis on the standing sagittal lumbar spine alignment and to investigate if a dynamic spine system can replace the commonly used rigid systems in order to avoid the above mentioned disadvantages of rigid fixation. 15 randomly selected patients received the rigid instrumentation SCS and an equal number of randomly selected patients the dynamic TWINFLEX device for spinal stenosis associated degenerative lumbar disease. The age of the patients, who received rigid and dynamic instrumentation was 65 +/- 9 years and 62 +/- 10 years respectively. All patients had standing spine radiographs preoperatively and three months postoperatively. The parameters that were measured and compared pre- to postoperatively were: lumbar lordosis (L1-S1), total lumbar lordosis (T12-S1), sacral tilt, distal lordosis (L4-S1), intervertebral angulation, vertebral inclination and disc index. The instrumented levels in the spines that received rigid and dynamic instrumentation were 3.5 +/- 0.53 and 3 +/- 0.7 respectively. The instrumented levels from L3 to L5 were 23, the lumbosacral junction was instrumented in 3 patients of group A and in 4 patients of group B. Lumbar lordosis did not significantly change postoperatively, while total lordosis was significantly (P=0.04) increased in the patients who received the rigid instrumentation, while it was significantly (P=0.012) decreased in the group B. Intervertebral angulation of the non-instrumented level L1-L2 was increased in the group A (P=0.01), while the dynamic instrumentation increased (P=0.02) the intervertebral inclination of the adjacent level L2-L3, immediately above the uppermost instrumented level. Distal lordosis and sacral tilt did not change in any patient in both groups. Both instrumentations did not change the lateral vertebral inclination of L1 to L5

  2. Absorption of a rigid frame porous layer with periodic circular inclusions backed by a periodic grating.

    PubMed

    Groby, J-P; Duclos, A; Dazel, O; Boeckx, L; Lauriks, W

    2011-05-01

    The acoustic properties of a periodic rigid frame porous layer with multiple irregularities in the rigid backing and embedded rigid circular inclusions are investigated theoretically and numerically. The theoretical representation of the sound field in the structure is obtained using a combination of multipole method that accounts for the periodic inclusions and multi-modal method that accounts for the multiple irregularities of the rigid backing. The theoretical model is validated against a finite element method. The predictions show that the acoustic response of this structure exhibits quasi-total, high absorption peaks at low frequencies which are below the frequency of the quarter-wavelength resonance typical for a flat homogeneous porous layer backed by a rigid plate. This result is explained by excitation of additional modes in the porous layer and by a complex interaction between various acoustic modes. These modes relate to the resonances associated with the presence of a profiled rigid backing and rigid inclusions in the porous layer.

  3. Green waste cooking oil-based rigid polyurethane foam

    NASA Astrophysics Data System (ADS)

    Enderus, N. F.; Tahir, S. M.

    2017-11-01

    Polyurethane is a versatile polymer traditionally prepared using petroleum-based raw material. Petroleum, however, is a non-renewable material and polyurethane produced was found to be non-biodegradable. In quest for a more environmentally friendly alternative, wastecooking oil, a highly abundant domestic waste with easily derivatized structure, is a viable candidate to replace petroleum. In this study,an investigation to determine physical and chemical properties of rigid polyurethane (PU) foam from waste cooking oil (WCO) was carried out. WCO was first adsorbed by using coconut husk activated carbon adsorbent prior to be used for polyol synthesis. The purified WCO was then used to synthesize polyol via transesterification reaction to yield alcohol groups in the WCO chains structure. Finally, the WCO-based polyol was used to prepare rigid PU foam. The optimum formulation for PU formation was found to be 90 polyol: 60 glycerol: 54 water: 40 diethanolamine: 23 diisocyanate. The rigid PU foam has density of 208.4 kg/m3 with maximum compressive strength and capability to receive load at 0.03 MPa and 0.09 kN, respectively. WCO-based PU can potentially be used to replace petroleum-based PU as house construction materials such as insulation panels.

  4. Towards accurate modeling of noncovalent interactions for protein rigidity analysis.

    PubMed

    Fox, Naomi; Streinu, Ileana

    2013-01-01

    Protein rigidity analysis is an efficient computational method for extracting flexibility information from static, X-ray crystallography protein data. Atoms and bonds are modeled as a mechanical structure and analyzed with a fast graph-based algorithm, producing a decomposition of the flexible molecule into interconnected rigid clusters. The result depends critically on noncovalent atomic interactions, primarily on how hydrogen bonds and hydrophobic interactions are computed and modeled. Ongoing research points to the stringent need for benchmarking rigidity analysis software systems, towards the goal of increasing their accuracy and validating their results, either against each other and against biologically relevant (functional) parameters. We propose two new methods for modeling hydrogen bonds and hydrophobic interactions that more accurately reflect a mechanical model, without being computationally more intensive. We evaluate them using a novel scoring method, based on the B-cubed score from the information retrieval literature, which measures how well two cluster decompositions match. To evaluate the modeling accuracy of KINARI, our pebble-game rigidity analysis system, we use a benchmark data set of 20 proteins, each with multiple distinct conformations deposited in the Protein Data Bank. Cluster decompositions for them were previously determined with the RigidFinder method from Gerstein's lab and validated against experimental data. When KINARI's default tuning parameters are used, an improvement of the B-cubed score over a crude baseline is observed in 30% of this data. With our new modeling options, improvements were observed in over 70% of the proteins in this data set. We investigate the sensitivity of the cluster decomposition score with case studies on pyruvate phosphate dikinase and calmodulin. To substantially improve the accuracy of protein rigidity analysis systems, thorough benchmarking must be performed on all current systems and future

  5. Towards accurate modeling of noncovalent interactions for protein rigidity analysis

    PubMed Central

    2013-01-01

    Background Protein rigidity analysis is an efficient computational method for extracting flexibility information from static, X-ray crystallography protein data. Atoms and bonds are modeled as a mechanical structure and analyzed with a fast graph-based algorithm, producing a decomposition of the flexible molecule into interconnected rigid clusters. The result depends critically on noncovalent atomic interactions, primarily on how hydrogen bonds and hydrophobic interactions are computed and modeled. Ongoing research points to the stringent need for benchmarking rigidity analysis software systems, towards the goal of increasing their accuracy and validating their results, either against each other and against biologically relevant (functional) parameters. We propose two new methods for modeling hydrogen bonds and hydrophobic interactions that more accurately reflect a mechanical model, without being computationally more intensive. We evaluate them using a novel scoring method, based on the B-cubed score from the information retrieval literature, which measures how well two cluster decompositions match. Results To evaluate the modeling accuracy of KINARI, our pebble-game rigidity analysis system, we use a benchmark data set of 20 proteins, each with multiple distinct conformations deposited in the Protein Data Bank. Cluster decompositions for them were previously determined with the RigidFinder method from Gerstein's lab and validated against experimental data. When KINARI's default tuning parameters are used, an improvement of the B-cubed score over a crude baseline is observed in 30% of this data. With our new modeling options, improvements were observed in over 70% of the proteins in this data set. We investigate the sensitivity of the cluster decomposition score with case studies on pyruvate phosphate dikinase and calmodulin. Conclusion To substantially improve the accuracy of protein rigidity analysis systems, thorough benchmarking must be performed on all

  6. The ISOMAX Magnetic Rigidity Spectrometer

    NASA Astrophysics Data System (ADS)

    Hams, Thomas

    1999-08-01

    The Isotope Magnet Experiment, (ISOMAX), is a balloon-borne superconducting magnetic spectrometer with a time-of-flight system and aerogel Cherenkov counters. Its purpose is to measure the isotopic composition of the light elements (3 < Z < 8) in the cosmic radiation. Particle mass is derived from a velocity vs. magnetic rigidity (momentum/charge) technique. The experiment had its first flight in August 1998. The precision magnetic spectrometer uses advanced drift-chamber tracking and a large, high-field, superconducting magnet. The drift-chamber system consists of three chambers with 24 layers of hexagonal drift cells (16 bending, 8 non-bending) and a vertical extent of 1.4 m. Pure CO2 gas is used. The magnet is a split-pair design with 79 cm diameter coils and a separation of 80 cm. During the 1998 flight, the central field was 0.8 T (60% of the full design field). Presented are results from flight data, for a range of incident particle Z, on the spatial resolution and efficiency of the tracking system, and on the maximum detectable rigidity (MDR) of the spectrometer. For in-flight data, spatial resolutions of 54 mm for Z=2 and 45 mm for Z=4 are obtained. An MDR of 970 GV/c is achieved for Z=2.

  7. Understanding Behavioural Rigidity in Autism Spectrum Conditions: The Role of Intentional Control

    ERIC Educational Resources Information Center

    Poljac, Edita; Hoofs, Vincent; Princen, Myrthe M.; Poljac, Ervin

    2017-01-01

    Although behavioural rigidity belongs to the core symptoms of autism spectrum conditions, little is known about its underlying cognitive mechanisms. The current study investigated the role of intentional control mechanisms in behavioural rigidity in autism. Autistic individuals and their matched controls were instructed to repeatedly choose…

  8. Multiscale multiphysics and multidomain models—Flexibility and rigidity

    PubMed Central

    Xia, Kelin; Opron, Kristopher; Wei, Guo-Wei

    2013-01-01

    The emerging complexity of large macromolecules has led to challenges in their full scale theoretical description and computer simulation. Multiscale multiphysics and multidomain models have been introduced to reduce the number of degrees of freedom while maintaining modeling accuracy and achieving computational efficiency. A total energy functional is constructed to put energies for polar and nonpolar solvation, chemical potential, fluid flow, molecular mechanics, and elastic dynamics on an equal footing. The variational principle is utilized to derive coupled governing equations for the above mentioned multiphysical descriptions. Among these governing equations is the Poisson-Boltzmann equation which describes continuum electrostatics with atomic charges. The present work introduces the theory of continuum elasticity with atomic rigidity (CEWAR). The essence of CEWAR is to formulate the shear modulus as a continuous function of atomic rigidity. As a result, the dynamics complexity of a macromolecular system is separated from its static complexity so that the more time-consuming dynamics is handled with continuum elasticity theory, while the less time-consuming static analysis is pursued with atomic approaches. We propose a simple method, flexibility-rigidity index (FRI), to analyze macromolecular flexibility and rigidity in atomic detail. The construction of FRI relies on the fundamental assumption that protein functions, such as flexibility, rigidity, and energy, are entirely determined by the structure of the protein and its environment, although the structure is in turn determined by all the interactions. As such, the FRI measures the topological connectivity of protein atoms or residues and characterizes the geometric compactness of the protein structure. As a consequence, the FRI does not resort to the interaction Hamiltonian and bypasses matrix diagonalization, which underpins most other flexibility analysis methods. FRI's computational complexity is of

  9. Cosmic Rays In The Magnetosphere, 2. Apparent Cut-off Rigidities and Coupling Functions

    NASA Astrophysics Data System (ADS)

    Dorman, L. I.; Danilova, O. A.; Iucci, N.; Parisi, M.; Ptitsyna, N. G.; Tyasto, M. I.; Villoresi, G.

    We calculate the apparent cut-off rigidities along the survey Italy-Antarctica-Italy** on the basis of results of Danilova et al. (2001) on trajectory calculations for inclined cut- off rigidities at eight azimuths (through 45?) and five zeniths angles (through 15?) along the survey. For calculations of apparent cut-off rigidities we use also the infor- mation on integral multiplicities of secondary neutrons in dependence of zenith angle of incident primary cosmic ray particles, as theoretically computed. This information is based on the theoretical calculations of meson-nuclear cascades for primary protons with different rigidities arriving to the EarthSs atmosphere at different zenith angles (Dorman and Pakhomov, 1979). These results have been checked and normalized by using coupling functions obtained in the same survey [Dorman et al. (2000)]. The determined apparent cut-off rigidities have been compared with results obtained by Clem et al. (1997) and with those used by Dorman et al. (2000) computed by using vertical cut-off rigidities, for trajectories especially calculated for the survey. On the basis of the apparent cut-off rigidities along the latitude survey, the coupling functions for neutron monitor and bare neutron counters found by Dorman et al. (2000) are now determined more accurately. **Survey realized with logistic and financial support of the Italian Antarctic Program (PNRA) and with the co-operation of IFSI-CNR. REFERENCES: Clem, J.M., et al. J. Geophys. Res., 102, 26,919 (1997). Danilova, O.A., et al., Latitude survey in December 1996-March 1997, 1. Cut-off rigidities for different azimuth and zenith angles, Paper ST13, This issue (2001) Dorman L.I. and Pakhomov N.I., "The dependence of the integral generation multiplicity of neutron component at various depths in the atmosphere on zenith angle on primary particle in- cidence". Proc. 16-th ICRC, Kyoto, 4, 416-420 (1979) Dorman, L.I., et al., J. Geophys. Res. 105 , 21,047 (2000).

  10. Rigid spine reinforced polymer microelectrode array probe and method of fabrication

    DOEpatents

    Tabada, Phillipe; Pannu, Satinderpall S

    2014-05-27

    A rigid spine-reinforced microelectrode array probe and fabrication method. The probe includes a flexible elongated probe body with conductive lines enclosed within a polymeric material. The conductive lines connect microelectrodes found near an insertion end of the probe to respective leads at a connector end of the probe. The probe also includes a rigid spine, such as made from titanium, fixedly attached to the probe body to structurally reinforce the probe body and enable the typically flexible probe body to penetrate and be inserted into tissue, such as neural tissue. By attaching or otherwise fabricating the rigid spine to connect to only an insertion section of the probe body, an integrally connected cable section of the probe body may remain flexible.

  11. Electromagnetic Scattering by Fully Ordered and Quasi-Random Rigid Particulate Samples

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.; Dlugach, Janna M.; Mackowski, Daniel W.

    2016-01-01

    In this paper we have analyzed circumstances under which a rigid particulate sample can behave optically as a true discrete random medium consisting of particles randomly moving relative to each other during measurement. To this end, we applied the numerically exact superposition T-matrix method to model far-field scattering characteristics of fully ordered and quasi-randomly arranged rigid multiparticle groups in fixed and random orientations. We have shown that, in and of itself, averaging optical observables over movements of a rigid sample as a whole is insufficient unless it is combined with a quasi-random arrangement of the constituent particles in the sample. Otherwise, certain scattering effects typical of discrete random media (including some manifestations of coherent backscattering) may not be accurately replicated.

  12. Parameter Optimization of Pseudo-Rigid-Body Models of MRI-Actuated Catheters

    PubMed Central

    Greigarn, Tipakorn; Liu, Taoming; Çavuşoğlu, M. Cenk

    2016-01-01

    Simulation and control of a system containing compliant mechanisms such as cardiac catheters often incur high computational costs. One way to reduce the costs is to approximate the mechanisms with Pseudo-Rigid-Body Models (PRBMs). A PRBM generally consists of rigid links connected by spring-loaded revolute joints. The lengths of the rigid links and the stiffnesses of the springs are usually chosen to minimize the tip deflection differences between the PRBM and the compliant mechanism. In most applications, only the relationship between end load and tip deflection is considered. This is obviously not applicable for MRI-actuated catheters which is actuated by the coils attached to the body. This paper generalizes PRBM parameter optimization to include loading and reference points along the body. PMID:28261009

  13. Mitral stenosis due to pannus overgrowth after rigid ring annuloplasty.

    PubMed

    Oda, Takeshi; Kato, Seiya; Tayama, Eiki; Fukunaga, Shuji; Akashi, Hidetoshi; Aoyagi, Shigeaki

    2010-03-01

    Although mitral stenosis (MS) due to pannus overgrowth after mitral valve repair for rheumatic mitral regurgitation (MR) is not uncommon, it is extremely rare in relation to non-rheumatic mitral regurgitation. Whilst it has been suggested that the rigid annuloplasty ring induces pannus overgrowth in the same manner as the flexible ring, to date only in cases using the flexible ring has pannus formation been confirmed by a pathological examination after redo surgery. The case is described of a woman who had undergone mitral valve repair using a 28 mm rigid ring three years previously because of non-rheumatic MR, and subsequently suffered from MS due to pannus formation over the annuloplasty ring. To the present authors' knowledge, this is the first report of MS due to pannus formation after mitral valve repair using a rigid annuloplasty ring to treat non-rheumatic MR documented at reoperation.

  14. Authoritarianism, cognitive rigidity, and the processing of ambiguous visual information.

    PubMed

    Duncan, Lauren E; Peterson, Bill E

    2014-01-01

    Intolerance of ambiguity and cognitive rigidity are unifying aspects of authoritarianism as defined by Adorno, Frenkel-Brunswik, Levinson, and Sanford (1982/1950), who hypothesized that authoritarians view the world in absolute terms (e.g., good or evil). Past studies have documented the relationship between authoritarianism and intolerance of ambiguity and rigidity. Frenkel-Brunswik (1949) hypothesized that this desire for absolutism was rooted in perceptual processes. We present a study with three samples that directly tests the relationship between right wing authoritarianism (RWA) and the processing of ideologically neutral but ambiguous visual stimuli. As hypothesized, in all three samples we found that RWA was related to the slower processing of visual information that required participants to recategorize objects. In a fourth sample, RWA was unrelated to speed of processing visual information that did not require recategorization. Overall, results suggest a relationship between RWA and rigidity in categorization.

  15. Enhancement in Elastic Bending Rigidity of Polymer Loaded Reverse Microemulsions.

    PubMed

    Geethu, P M; Yadav, Indresh; Aswal, Vinod K; Satapathy, Dillip K

    2017-11-14

    Elastic bending rigidity of the surfactant shell is a crucial parameter which determines the phase behavior and stability of microemulsion droplets. For water-in-oil reverse microemulsions stabilized by AOT (sodium 1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate) surfactant, the elastic bending rigidity is close to thermal energy at room temperature (k B T) and can be modified by the presence of hydrophilic polymers. Here, we explore the influence of two polymers polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP), both having nearly same size (radius of gyration, R g ) but different dipole moment, on elastic bending rigidity of water-AOT-n-decane reverse microemulsions via estimating the percolation temperatures (T P ) and droplet radii using dielectric relaxation spectroscopy (DRS) and small-angle neutron scattering (SANS) techniques. Notably, an increase in T P is observed on introducing PEG and PVP polymers and is attributed to the adsorption of polymer chains onto the surfactant monolayer. The stability of the droplet phase of microemulsion after the incorporation of PEG and PVP polymers is confirmed by contrast matching SANS experiments. An enhancement in elastic bending rigidity of AOT surfactant shell amounting to ∼46% is observed upon incorporation of PVP into the droplet core, whereas for PEG addition, a smaller increase of about 17% is recorded. We conjecture that the considerable increase in elastic bending rigidity of the surfactant monolayer upon introducing PVP is because of the strong ion-dipole interaction between anionic AOT and dipoles present along the PVP polymer chains. Scaling exponents extracted from the temperature dependent electrical conductivity measurements and the frequency dependent scaling of conductivity at percolation indicate the dynamic nature of percolation for both pure and polymer loaded reverse microemulsions. The decrease in activation energy of percolation upon incorporating PEG and PVP polymer molecules also

  16. Optical detection of nanometric thermal fluctuations to measure the stiffness of rigid superparamagnetic microrods

    PubMed Central

    Wang, Yuan

    2017-01-01

    The rigidity of numerous biological filaments and crafted microrods has been conveniently deduced from the analysis of their thermal fluctuations. However, the difficulty of measuring nanometric displacements with an optical microscope has so far limited such studies to sufficiently flexible rods, of which the persistence length (Lp) rarely exceeds 1 m at room temperature. Here, we demonstrate the possibility to probe 10-fold stiffer rods by a combination of superresolutive optical methods and a statistical analysis of the data based on a recent theoretical model that predicts the amplitude of the fluctuations at any location of the rod [Benetatos P, Frey E (2003) Phys Rev E Stat Nonlin Soft Matter Phys 67(5):051108]. Using this approach, we report measures of Lp up to 0.5 km. We obtained these measurements on recently designed superparamagnetic ∼40-μm-long microrods containing iron-oxide nanoparticles connected by a polymer mesh. Using their magnetic properties, we provide an alternative proof of validity of these thermal measurements: For each individual studied rod, we performed a second measure of its rigidity by deflecting it with a uniform magnetic field. The agreement between the thermal and the magnetoelastic measures was realized with more than a decade of values of Lp from 5.1 m to 129 m, corresponding to a bending modulus ranging from 2.2 to 54 (×10−20 Jm). Despite the apparent homogeneity of the analyzed microrods, their Young modulus follows a broad distribution from 1.9 MPa to 59 MPa and up to 200 MPa, depending on the size of the nanoparticles. PMID:28228530

  17. Learned Non-Rigid Object Motion is a View-Invariant Cue to Recognizing Novel Objects

    PubMed Central

    Chuang, Lewis L.; Vuong, Quoc C.; Bülthoff, Heinrich H.

    2012-01-01

    There is evidence that observers use learned object motion to recognize objects. For instance, studies have shown that reversing the learned direction in which a rigid object rotated in depth impaired recognition accuracy. This motion reversal can be achieved by playing animation sequences of moving objects in reverse frame order. In the current study, we used this sequence-reversal manipulation to investigate whether observers encode the motion of dynamic objects in visual memory, and whether such dynamic representations are encoded in a way that is dependent on the viewing conditions. Participants first learned dynamic novel objects, presented as animation sequences. Following learning, they were then tested on their ability to recognize these learned objects when their animation sequence was shown in the same sequence order as during learning or in the reverse sequence order. In Experiment 1, we found that non-rigid motion contributed to recognition performance; that is, sequence-reversal decreased sensitivity across different tasks. In subsequent experiments, we tested the recognition of non-rigidly deforming (Experiment 2) and rigidly rotating (Experiment 3) objects across novel viewpoints. Recognition performance was affected by viewpoint changes for both experiments. Learned non-rigid motion continued to contribute to recognition performance and this benefit was the same across all viewpoint changes. By comparison, learned rigid motion did not contribute to recognition performance. These results suggest that non-rigid motion provides a source of information for recognizing dynamic objects, which is not affected by changes to viewpoint. PMID:22661939

  18. Settling dynamics of asymmetric rigid fibers

    Treesearch

    E.J. Tozzi; C Tim Scott; David Vahey; D.J. Klingenberg

    2011-01-01

    The three-dimensional motion of asymmetric rigid fibers settling under gravity in a quiescent fluid was experimentally measured using a pair of cameras located on a movable platform. The particle motion typically consisted of an initial transient after which the particle approached a steady rate of rotation about an axis parallel to the acceleration of gravity, with...

  19. Stretchy Proteins on Stretchy Substrates: The Important Elements of Integrin-Mediated Rigidity Sensing

    PubMed Central

    Moore, Simon W.; Roca-Cusachs, Pere; Sheetz, Michael P.

    2013-01-01

    Matrix and tissue rigidity guides many cellular processes, including the differentiation of stem cells and the migration of cells in health and disease. Cells actively and transiently test rigidity using mechanisms limited by inherent physical parameters that include the strength of extracellular attachments, the pulling capacity on these attachments, and the sensitivity of the mechanotransduction system. Here we focus on rigidity sensing mediated through the integrin family of extracellular matrix receptors and linked proteins, and discuss the evidence supporting these proteins as mechanosensors. PMID:20708583

  20. Calculations of critical micelle concentration by dissipative particle dynamics simulations: the role of chain rigidity.

    PubMed

    Lee, Ming-Tsung; Vishnyakov, Aleksey; Neimark, Alexander V

    2013-09-05

    Micelle formation in surfactant solutions is a self-assembly process governed by complex interplay of solvent-mediated interactions between hydrophilic and hydrophobic groups, which are commonly called heads and tails. However, the head-tail repulsion is not the only factor affecting the micelle formation. For the first time, we present a systematic study of the effect of chain rigidity on critical micelle concentration and micelle size, which is performed with the dissipative particle dynamics simulation method. Rigidity of the coarse-grained surfactant molecule was controlled by the harmonic bonds set between the second-neighbor beads. Compared to flexible molecules with the nearest-neighbor bonds being the only type of bonded interactions, rigid molecules exhibited a lower critical micelle concentration and formed larger and better-defined micelles. By varying the strength of head-tail repulsion and the chain rigidity, we constructed two-dimensional diagrams presenting how the critical micelle concentration and aggregation number depend on these parameters. We found that the solutions of flexible and rigid molecules that exhibited approximately the same critical micelle concentration could differ substantially in the micelle size and shape depending on the chain rigidity. With the increase of surfactant concentration, primary micelles of more rigid molecules were found less keen to agglomeration and formation of nonspherical aggregates characteristic of flexible molecules.

  1. Matching multiple rigid domain decompositions of proteins

    PubMed Central

    Flynn, Emily; Streinu, Ileana

    2017-01-01

    We describe efficient methods for consistently coloring and visualizing collections of rigid cluster decompositions obtained from variations of a protein structure, and lay the foundation for more complex setups that may involve different computational and experimental methods. The focus here is on three biological applications: the conceptually simpler problems of visualizing results of dilution and mutation analyses, and the more complex task of matching decompositions of multiple NMR models of the same protein. Implemented into the KINARI web server application, the improved visualization techniques give useful information about protein folding cores, help examining the effect of mutations on protein flexibility and function, and provide insights into the structural motions of PDB proteins solved with solution NMR. These tools have been developed with the goal of improving and validating rigidity analysis as a credible coarse-grained model capturing essential information about a protein’s slow motions near the native state. PMID:28141528

  2. Pediatric mandibular fractures treated by rigid internal fixation.

    PubMed

    Wong, G B

    1993-09-01

    Mandibular fractures in the pediatric patient population are relatively uncommon. These patients present with their own unique treatment requirements. Most fractures have been treated conservatively by dental splints. Closed reduction techniques with maxillomandibular fixation (MMF) in very young children can pose several concerns, including cooperation, compliance and adequate nutritional intake. Rigid internal fixation of unstable mandibular fractures using miniplates and screws circumvents the need for MMF and allows immediate jaw mobilization. At major pediatric trauma institutions, there has been an increasing trend toward the use of this treatment when open reduction is necessary. This article presents a report of a five-year-old child who presented with bilateral mandibular fractures and was treated by rigid internal fixation and immediate mandibular mobilization.

  3. Stresses in Circular Plates with Rigid Elements

    NASA Astrophysics Data System (ADS)

    Velikanov, N. L.; Koryagin, S. I.; Sharkov, O. V.

    2018-05-01

    Calculations of residual stress fields are carried out by numerical and static methods, using the flat cross-section hypothesis. The failure of metal when exposed to residual stresses is, in most cases, brittle. The presence in the engineering structures of rigid elements often leads to the crack initiation and structure failure. This is due to the fact that rigid elements under the influence of external stresses are stress concentrators. In addition, if these elements are fixed by welding, the residual welding stresses can lead to an increase in stress concentration and, ultimately, to failure. The development of design schemes for such structures is a very urgent task for complex technical systems. To determine the stresses in a circular plate with a welded circular rigid insert under the influence of an external load, one can use the solution of the plane stress problem for annular plates in polar coordinates. The polar coordinates of the points are the polar radius and the polar angle, and the stress state is determined by normal radial stresses, tangential and shearing stresses. The use of the above mentioned design schemes, formulas, will allow more accurate determination of residual stresses in annular welded structures. This will help to establish the most likely directions of failure and take measures at the stages of designing, manufacturing and repairing engineering structures to prevent these failures. However, it must be taken into account that the external load, the presence of insulation can lead to a change in the residual stress field.

  4. An Interface for Specifying Rigid-Body Motions for CFD Applications

    NASA Technical Reports Server (NTRS)

    Murman, Scott M.; Chan, William; Aftosmis, Michael; Meakin, Robert L.; Kwak, Dochan (Technical Monitor)

    2003-01-01

    An interface for specifying rigid-body motions for CFD applications is presented. This interface provides a means of describing a component hierarchy in a geometric configuration, as well as the motion (prescribed or six-degree-of-freedom) associated with any component. The interface consists of a general set of datatypes, along with rules for their interaction, and is designed to be flexible in order to evolve as future needs dictate. The specification is currently implemented with an XML file format which is portable across platforms and applications. The motion specification is capable of describing general rigid body motions, and eliminates the need to write and compile new code within the application software for each dynamic configuration, allowing client software to automate dynamic simulations. The interface is integrated with a GUI tool which allows rigid body motions to be prescribed and verified interactively, promoting access to non-expert users. Illustrative examples, as well as the raw XML source of the file specifications, are included.

  5. Heat Transfer Measurement and Modeling in Rigid High-Temperature Reusable Surface Insulation Tiles

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Knutson, Jeffrey R.; Cunnington, George R.

    2011-01-01

    Heat transfer in rigid reusable surface insulations was investigated. Steady-state thermal conductivity measurements in a vacuum were used to determine the combined contribution of radiation and solid conduction components of heat transfer. Thermal conductivity measurements at higher pressures were then used to estimate the effective insulation characteristic length for gas conduction modeling. The thermal conductivity of the insulation can then be estimated at any temperature and pressure in any gaseous media. The methodology was validated by comparing estimated thermal conductivities with published data on a rigid high-temperature silica reusable surface insulation tile. The methodology was also applied to the alumina enhanced thermal barrier tiles. Thermal contact resistance for thermal conductivity measurements on rigid tiles was also investigated. A technique was developed to effectively eliminate thermal contact resistance on the rigid tile s cold-side surface for the thermal conductivity measurements.

  6. Phosphorescence and Energy Transfer in Rigid Solutions.

    ERIC Educational Resources Information Center

    Enciso, E.; Cabello, A.

    1980-01-01

    Describes an experiment which illustrates the general aspects of intermolecular energy transfer between triplet states in rigid solutions of organic compounds solved in an ethanol-ether mixture. Measurements of quenching and energy transfer processes are made using the chemicals of benzophenone and naphthalene. (CS)

  7. A rigidity transition and glassy dynamics in a model for confluent 3D tissues

    NASA Astrophysics Data System (ADS)

    Merkel, Matthias; Manning, M. Lisa

    The origin of rigidity in disordered materials is an outstanding open problem in statistical physics. Recently, a new type of rigidity transition was discovered in a family of models for 2D biological tissues, but the mechanisms responsible for rigidity remain unclear. This is not just a statistical physics problem, but also relevant for embryonic development, cancer growth, and wound healing. To gain insight into this rigidity transition and make new predictions about biological bulk tissues, we have developed a fully 3D self-propelled Voronoi (SPV) model. The model takes into account shape, elasticity, and self-propelled motion of the individual cells. We find that in the absence of self-propulsion, this model exhibits a rigidity transition that is controlled by a dimensionless model parameter describing the preferred cell shape, with an accompanying structural order parameter. In the presence of self-propulsion, the rigidity transition appears as a glass-like transition featuring caging and aging effects. Given the similarities between this transition and jamming in particulate solids, it is natural to ask if the two transitions are related. By comparing statistics of Voronoi geometries, we show the transitions are surprisingly close but demonstrably distinct. Furthermore, an index theorem used to identify topologically protected mechanical modes in jammed systems can be extended to these vertex-type models. In our model, residual stresses govern the transition and enter the index theorem in a different way compared to jammed particles, suggesting the origin of rigidity may be different between the two.

  8. Changes in E-cadherin rigidity sensing regulate cell adhesion.

    PubMed

    Collins, Caitlin; Denisin, Aleksandra K; Pruitt, Beth L; Nelson, W James

    2017-07-18

    Mechanical cues are sensed and transduced by cell adhesion complexes to regulate diverse cell behaviors. Extracellular matrix (ECM) rigidity sensing by integrin adhesions has been well studied, but rigidity sensing by cadherins during cell adhesion is largely unexplored. Using mechanically tunable polyacrylamide (PA) gels functionalized with the extracellular domain of E-cadherin (Ecad-Fc), we showed that E-cadherin-dependent epithelial cell adhesion was sensitive to changes in PA gel elastic modulus that produced striking differences in cell morphology, actin organization, and membrane dynamics. Traction force microscopy (TFM) revealed that cells produced the greatest tractions at the cell periphery, where distinct types of actin-based membrane protrusions formed. Cells responded to substrate rigidity by reorganizing the distribution and size of high-traction-stress regions at the cell periphery. Differences in adhesion and protrusion dynamics were mediated by balancing the activities of specific signaling molecules. Cell adhesion to a 30-kPa Ecad-Fc PA gel required Cdc42- and formin-dependent filopodia formation, whereas adhesion to a 60-kPa Ecad-Fc PA gel induced Arp2/3-dependent lamellipodial protrusions. A quantitative 3D cell-cell adhesion assay and live cell imaging of cell-cell contact formation revealed that inhibition of Cdc42, formin, and Arp2/3 activities blocked the initiation, but not the maintenance of established cell-cell adhesions. These results indicate that the same signaling molecules activated by E-cadherin rigidity sensing on PA gels contribute to actin organization and membrane dynamics during cell-cell adhesion. We hypothesize that a transition in the stiffness of E-cadherin homotypic interactions regulates actin and membrane dynamics during initial stages of cell-cell adhesion.

  9. Changes in E-cadherin rigidity sensing regulate cell adhesion

    PubMed Central

    Collins, Caitlin; Pruitt, Beth L.; Nelson, W. James

    2017-01-01

    Mechanical cues are sensed and transduced by cell adhesion complexes to regulate diverse cell behaviors. Extracellular matrix (ECM) rigidity sensing by integrin adhesions has been well studied, but rigidity sensing by cadherins during cell adhesion is largely unexplored. Using mechanically tunable polyacrylamide (PA) gels functionalized with the extracellular domain of E-cadherin (Ecad-Fc), we showed that E-cadherin–dependent epithelial cell adhesion was sensitive to changes in PA gel elastic modulus that produced striking differences in cell morphology, actin organization, and membrane dynamics. Traction force microscopy (TFM) revealed that cells produced the greatest tractions at the cell periphery, where distinct types of actin-based membrane protrusions formed. Cells responded to substrate rigidity by reorganizing the distribution and size of high-traction-stress regions at the cell periphery. Differences in adhesion and protrusion dynamics were mediated by balancing the activities of specific signaling molecules. Cell adhesion to a 30-kPa Ecad-Fc PA gel required Cdc42- and formin-dependent filopodia formation, whereas adhesion to a 60-kPa Ecad-Fc PA gel induced Arp2/3-dependent lamellipodial protrusions. A quantitative 3D cell–cell adhesion assay and live cell imaging of cell–cell contact formation revealed that inhibition of Cdc42, formin, and Arp2/3 activities blocked the initiation, but not the maintenance of established cell–cell adhesions. These results indicate that the same signaling molecules activated by E-cadherin rigidity sensing on PA gels contribute to actin organization and membrane dynamics during cell–cell adhesion. We hypothesize that a transition in the stiffness of E-cadherin homotypic interactions regulates actin and membrane dynamics during initial stages of cell–cell adhesion. PMID:28674019

  10. Water vapor permeability of the rigid-shelled gecko egg.

    PubMed

    Andrews, Robin M

    2012-07-01

    The vast majority of squamate reptiles (lizards and snakes) produce parchment-shelled eggs that absorb water during incubation, and thus increase in mass, volume, and surface area. In contrast, females from a single monophyletic lineage of gekkotan lizards produce rigid-shelled eggs. These eggs are functionally comparable to those of birds, that is, at oviposition, eggs contain all the water needed for development, and their mass decreases during incubation via the diffusion of water vapor through the shell. I determined patterns of water loss and shell permeability to water vapor from oviposition to hatching for the rigid-shelled eggs of the gekkonid Chrondrodactylus turneri and compared permeability of C. turneri eggs to those of birds and other squamates. Chrondrodactylus turneri eggs incubated at 28.5°C and 40% relative humidity (RH) decreased in mass by 14% over the course of a 68-day incubation period. The rate of water loss varied during incubation; egg mass decreased rapidly during the first 8 days of incubation, declined at a low constant rate during the next 35 days, and then decreased rapidly during the final 25 days of incubation. Overall permeability was 0.17 mg/day/kPa/cm(2) . Percent water loss of rigid-shelled gecko eggs during incubation is similar to that exhibited by birds, but water vapor permeability is about one-third that of bird eggs and several orders of magnitude lower than that of parchment-shelled squamate eggs. In general, the water economy of their eggs may be associated with the adaptive radiation of the rigid-shelled sphaerodactylid, phyllodactylid, and gekkonid geckos. © 2012 WILEY PERIODICALS, INC.

  11. Prediction-based sampled-data H∞ controller design for attitude stabilisation of a rigid spacecraft with disturbances

    NASA Astrophysics Data System (ADS)

    Zhu, Baolong; Zhang, Zhiping; Zhou, Ding; Ma, Jie; Li, Shunli

    2017-08-01

    This paper investigates the H∞ control problem of the attitude stabilisation of a rigid spacecraft with external disturbances using prediction-based sampled-data control strategy. Aiming to achieve a 'virtual' closed-loop system, a type of parameterised sampled-data controller is designed by introducing a prediction mechanism. The resultant closed-loop system is equivalent to a hybrid system featured by a continuous-time and an impulsive differential system. By using a time-varying Lyapunov functional, a generalised bounded real lemma (GBRL) is first established for a kind of impulsive differential system. Based on this GBRL and Lyapunov functional approach, a sufficient condition is derived to guarantee the closed-loop system to be asymptotically stable and to achieve a prescribed H∞ performance. In addition, the controller parameter tuning is cast into a convex optimisation problem. Simulation and comparative results are provided to illustrate the effectiveness of the developed control scheme.

  12. A relativistic generalisation of rigid motions

    NASA Astrophysics Data System (ADS)

    Llosa, J.; Molina, A.; Soler, D.

    2012-07-01

    A weaker substitute for the too restrictive class of Born-rigid motions is proposed, which we call radar-holonomic motions. The definition is expressed as a set of differential equations. Integrability conditions and Cauchy problem are studied. We finally obtain an example of a radar-holonomic congruence containing a given worldline with a given value of the rotation on this line.

  13. Rigid Residue Scan Simulations Systematically Reveal Residue Entropic Roles in Protein Allostery

    PubMed Central

    Liu, Jin

    2016-01-01

    Intra-protein information is transmitted over distances via allosteric processes. This ubiquitous protein process allows for protein function changes due to ligand binding events. Understanding protein allostery is essential to understanding protein functions. In this study, allostery in the second PDZ domain (PDZ2) in the human PTP1E protein is examined as model system to advance a recently developed rigid residue scan method combining with configurational entropy calculation and principal component analysis. The contributions from individual residues to whole-protein dynamics and allostery were systematically assessed via rigid body simulations of both unbound and ligand-bound states of the protein. The entropic contributions of individual residues to whole-protein dynamics were evaluated based on covariance-based correlation analysis of all simulations. The changes of overall protein entropy when individual residues being held rigid support that the rigidity/flexibility equilibrium in protein structure is governed by the La Châtelier’s principle of chemical equilibrium. Key residues of PDZ2 allostery were identified with good agreement with NMR studies of the same protein bound to the same peptide. On the other hand, the change of entropic contribution from each residue upon perturbation revealed intrinsic differences among all the residues. The quasi-harmonic and principal component analyses of simulations without rigid residue perturbation showed a coherent allosteric mode from unbound and bound states, respectively. The projection of simulations with rigid residue perturbation onto coherent allosteric modes demonstrated the intrinsic shifting of ensemble distributions supporting the population-shift theory of protein allostery. Overall, the study presented here provides a robust and systematic approach to estimate the contribution of individual residue internal motion to overall protein dynamics and allostery. PMID:27115535

  14. Virtual rigid body: a new optical tracking paradigm in image-guided interventions

    NASA Astrophysics Data System (ADS)

    Cheng, Alexis; Lee, David S.; Deshmukh, Nishikant; Boctor, Emad M.

    2015-03-01

    Tracking technology is often necessary for image-guided surgical interventions. Optical tracking is one the options, but it suffers from line of sight and workspace limitations. Optical tracking is accomplished by attaching a rigid body marker, having a pattern for pose detection, onto a tool or device. A larger rigid body results in more accurate tracking, but at the same time large size limits its usage in a crowded surgical workspace. This work presents a prototype of a novel optical tracking method using a virtual rigid body (VRB). We define the VRB as a 3D rigid body marker in the form of pattern on a surface generated from a light source. Its pose can be recovered by observing the projected pattern with a stereo-camera system. The rigid body's size is no longer physically limited as we can manufacture small size light sources. Conventional optical tracking also requires line of sight to the rigid body. VRB overcomes these limitations by detecting a pattern projected onto the surface. We can project the pattern onto a region of interest, allowing the pattern to always be in the view of the optical tracker. This helps to decrease the occurrence of occlusions. This manuscript describes the method and results compared with conventional optical tracking in an experiment setup using known motions. The experiments are done using an optical tracker and a linear-stage, resulting in targeting errors of 0.38mm+/-0.28mm with our method compared to 0.23mm+/-0.22mm with conventional optical markers. Another experiment that replaced the linear stage with a robot arm resulted in rotational errors of 0.50+/-0.31° and 2.68+/-2.20° and the translation errors of 0.18+/-0.10 mm and 0.03+/-0.02 mm respectively.

  15. Acoustic radiation efficiency of a periodically corrugated rigid piston

    NASA Astrophysics Data System (ADS)

    Estrada, Héctor; Uris, Antonio; Meseguer, Francisco

    2012-09-01

    The radiation of sound by a periodically corrugated rigid piston is explored using theoretical and numerical approaches and compared with the radiation of flat rigid piston. The depth and the period of the corrugation are considered to be comparable with the wavelength in the surrounding fluid. Radiation enhancement is predicted due to cavity resonances and coherent diffraction. In addition, broad regions of low radiation efficiency are observed. Both effects could have an impact in acoustic transducers technology, either to increase the piston radiated power or to create a source of evanescent acoustic waves. The possibilities offered by this strategy in the nonlinear acoustic regime are also briefly discussed.

  16. Analysis of electric vehicle extended range misalignment based on rigid-flexible dynamics

    NASA Astrophysics Data System (ADS)

    Xu, Xiaowei; Lv, Mingliang; Chen, Zibo; Ji, Wei; Gao, Ruiceng

    2017-04-01

    The safety of the extended range electric vehicle is seriously affected by the misalignment fault. Therefore, this paper analyzed the electric vehicle extended range misalignment based on rigid-flexible dynamics. Through comprehensively applied the hybrid modeling of rigid-flexible and the method of fault diagnosis of machinery and equipment comprehensively, it established a extender hybrid rigid flexible mechanical model by means of the software ADAMS and ANSYS. By setting the relevant parameters to simulate the misalignment of shafting, the failure phenomenon, the spectrum analysis and the evolution rules were analyzed. It concluded that 0.5th and 1 harmonics are considered as the characteristic parameters of misalignment diagnostics for electric vehicle extended range.

  17. Hydrodynamic lubrication of rigid nonconformal contacts in combined rolling and normal motion

    NASA Technical Reports Server (NTRS)

    Ghosh, M. K.; Hamrock, B. J.; Brewe, D. E.

    1984-01-01

    A numerical solution to the problem of hydrodynamic lubrication of rigid point contacts with an isoviscous, incompressible lubricant was obtained. The hydrodynamic load-carrying capacity under unsteady (or dynamic) conditions arising from the combined effects of squeeze motion superposed upon the entraining motion was determined for both normal approach and separation. Superposed normal motion considerably increases net load-carrying capacity during normal approach and substantially reduces net load-carrying capacity during separation. Geometry was also found to have a significant influence on the dynamic load-carrying capacity. The ratio of dynamic to steady state load-carrying capacity increases with increasing geometry parameter for normal approach and decreases during separation. The cavitation (film rupture) boundary is also influenced significantly by the normal motion, moving downstream during approach and upstream during separation. For sufficiently high normal separation velocity the rupture boundary may even move upstream of the minimum-film-thickness position. Sixty-three cases were used to derive a functional relationship for the ratio of the dynamic to steady state load-carrying capacity in terms of the dimensionless normal velocity parameter (incorporating normal velocity, entraining velocity, and film thickness) and the geometry parameter.

  18. Hydrodynamic lubrication of rigid nonconformal contacts in combined rolling and normal motion

    NASA Technical Reports Server (NTRS)

    Ghosh, M. K.; Hamrock, B. J.; Brewe, D.

    1985-01-01

    A numerical solution to the problem of hydrodynamic lubrication of rigid point contacts with an isoviscous, incompressible lubricant was obtained. The hydrodynamic load-carrying capacity under unsteady (or dynamic) conditions arising from the combined effects of squeeze motion superposed upon the entraining motion was determined for both normal approach and separation. Superposed normal motion considerably increases net load-carrying capacity during normal approach and substantially reduces net load-carrying capacity during separation. Geometry was also found to have a significant influence on the dynamic load-carrying capacity. The ratio of dynamic to steady state load-carrying capacity increases with increasing geometry parameter for normal approach and decreases during separation. The cavitation (film rupture) boundary is also influenced significantly by the normal motion, moving downstream during approach and upstream during separation. For sufficiently high normal separation velocity the rupture boundary may even move upstream of the minimum-film-thickness position. Sixty-three cases were used to derive a functional relationship for the ratio of the dynamic to steady state load-carrying capacity in terms of the dimensionless normal velocity parameter (incorporating normal velocity, entraining velocity, and film thickness) and the geometry parameter.

  19. Condensin confers the longitudinal rigidity of chromosomes.

    PubMed

    Houlard, Martin; Godwin, Jonathan; Metson, Jean; Lee, Jibak; Hirano, Tatsuya; Nasmyth, Kim

    2015-06-01

    In addition to inter-chromatid cohesion, mitotic and meiotic chromatids must have three physical properties: compaction into 'threads' roughly co-linear with their DNA sequence, intra-chromatid cohesion determining their rigidity, and a mechanism to promote sister chromatid disentanglement. A fundamental issue in chromosome biology is whether a single molecular process accounts for all three features. There is universal agreement that a pair of Smc-kleisin complexes called condensin I and II facilitate sister chromatid disentanglement, but whether they also confer thread formation or longitudinal rigidity is either controversial or has never been directly addressed respectively. We show here that condensin II (beta-kleisin) has an essential role in all three processes during meiosis I in mouse oocytes and that its function overlaps with that of condensin I (gamma-kleisin), which is otherwise redundant. Pre-assembled meiotic bivalents unravel when condensin is inactivated by TEV cleavage, proving that it actually holds chromatin fibres together.

  20. Origami-Inspired Folding of Thick, Rigid Panels

    NASA Technical Reports Server (NTRS)

    Trease, Brian P.; Thomson, Mark W.; Sigel, Deborah A.; Walkemeyer, Phillip E.; Zirbel, Shannon; Howell, Larry; Lang, Robert

    2014-01-01

    To achieve power of 250 kW or greater, a large compression ratio of stowed-to-deployed area is needed. Origami folding patterns were used to inspire the folding of a solar array to achieve synchronous deployment; however, origami models are generally created for near-zero-thickness material. Panel thickness is one of the main challenges of origami-inspired design. Three origami-inspired folding techniques (flasher, square twist, and map fold) were created with rigid panels and hinges. Hinge components are added to the model to enable folding of thick, rigid materials. Origami models are created assuming zero (or near zero) thickness. When a material with finite thickness is used, the panels are required to bend around an increasingly thick fold as they move away from the center of the model. The two approaches for dealing with material thickness are to use membrane hinges to connect the panels, or to add panel hinges, or hinges of the same thickness, at an appropriate width to enable folding.

  1. Bifunctional role of leucine 300 of firefly luciferase in structural rigidity.

    PubMed

    Yousefi, Farzad; Ataei, Farangis; Mortazavi, Mojtaba; Hosseinkhani, Saman

    2017-08-01

    Firefly luciferase is susceptible to thermal inactivation, thereby its intracellular half-life decreased. Previous reports indicated that L 300 R mutation (LRR mutant) in E 354 R/Arg 356 double mutant (ERR mutant) from Lampyris turkestanicus luciferase has increased its thermal stability and rigidity through induction of some ionic bonds with Asp 270 and 271. Disruption of the deduced ionic bonds in an ultra-rigid mutant of firefly luciferase did not reverse the flexibility of the protein. In this study, we investigated the effects of this residue to find the truth behind an extraordinary increase in thermal stability and rigidity of luciferase after replacement of leucine 300 by arginine based on previous reports. For this purpose, L 300 R, L 300 K and L 300 E mutations were performed to compare the effects of these mutations on the native firefly luciferase. In spite of increase of intrinsic fluorescence of the mutants a slight increase in thermostability and retention of kinetic properties was observed. Based on our results, we can conclude that L 300 R mutation in LRR mutant accompanying with alteration in a flexible loop (352-359) increased thermostability and rigidity of luciferase. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Photogeneration of Charge Carriers in Bilayer Assemblies of Conjugated Rigid-Rod Polymers

    DTIC Science & Technology

    1994-07-08

    photoinduced electron transfer and exciplex formation at the bilayer interface. Thus photocarrier generation on photoexcitation of the conjugated rigid...rod polymers in the bilayer occurs by photoinduced electron transfer, forming intermolecular exciplexes which dissociate efficiently in electric field...photogeneration, conjugated rigid-rod polymers, is. MACI COD bilayer assemblies, electron transfer, exciplexes . 11. SEOJUTY CLASUICA 10. 51(11MIE CLASSIMIAVION

  3. Statistical Analysis of Bending Rigidity Coefficient Determined Using Fluorescence-Based Flicker-Noise Spectroscopy.

    PubMed

    Doskocz, Joanna; Drabik, Dominik; Chodaczek, Grzegorz; Przybyło, Magdalena; Langner, Marek

    2018-06-01

    Bending rigidity coefficient describes propensity of a lipid bilayer to deform. In order to measure the parameter experimentally using flickering noise spectroscopy, the microscopic imaging is required, which necessitates the application of giant unilamellar vesicles (GUV) lipid bilayer model. The major difficulty associated with the application of the model is the statistical character of GUV population with respect to their size and the homogeneity of lipid bilayer composition, if a mixture of lipids is used. In the paper, the bending rigidity coefficient was measured using the fluorescence-enhanced flicker-noise spectroscopy. In the paper, the bending rigidity coefficient was determined for large populations of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine vesicles. The quantity of obtained experimental data allows to perform statistical analysis aiming at the identification of the distribution, which is the most appropriate for the calculation of the value of the membrane bending rigidity coefficient. It has been demonstrated that the bending rigidity coefficient is characterized by an asymmetrical distribution, which is well approximated with the gamma distribution. Since there are no biophysical reasons for that we propose to use the difference between normal and gamma fits as a measure of the homogeneity of vesicle population. In addition, the effect of a fluorescent label and types of instrumental setups on determined values has been tested. Obtained results show that the value of the bending rigidity coefficient does not depend on the type of a fluorescent label nor on the type of microscope used.

  4. Substrate rigidity regulates Ca2+ oscillation via RhoA pathway in stem cells

    PubMed Central

    Kim, Tae-Jin; Seong, Jihye; Ouyang, Mingxing; Sun, Jie; Lu, Shaoying; Hong, Jun Pyu; Wang, Ning; Wang, Yingxiao

    2008-01-01

    Substrate rigidity plays crucial roles in regulating cellular functions, such as cell spreading, traction forces, and stem cell differentiation. However, it is not clear how substrate rigidity influences early cell signaling events such as calcium in living cells. Using highly-sensitive Ca2+ biosensors based on fluorescence resonance energy transfer (FRET), we investigated the molecular mechanism by which substrate rigidity affects calcium signaling in human mesenchymal stem cells (HMSCs). Spontaneous Ca2+ oscillations were observed inside the cytoplasm and the endoplasmic reticulum (ER) using the FRET biosensors targeted at subcellular locations in cells plated on rigid dishes. Lowering the substrate stiffness to 1 kPa significantly inhibited both the magnitudes and frequencies of the cytoplasmic Ca2+ oscillation in comparison to stiffer or rigid substrate. This Ca2+ oscillation was shown to be dependent on ROCK, a downstream effector molecule of RhoA, but independent of actin filaments, microtubules, myosin light chain kinase, or myosin activity. Lysophosphatidic acid, which activates RhoA, also inhibited the frequency of the Ca2+ oscillation. Consistently, either a constitutive active mutant of RhoA (RhoA-V14) or a dominant negative mutant of RhoA (RhoA-N19) inhibited the Ca2+ oscillation. Further experiments revealed that HMSCs cultured on gels with low elastic moduli displayed low RhoA activities. Therefore, our results demonstrate that RhoA and its downstream molecule ROCK may mediate the substrate rigidity-regulated Ca2+ oscillation, which determines the physiological functions of HMSCs. PMID:18844232

  5. Torsionally rigid support apparatus for marine seismic transducer

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

    Myers, W.J.; Cole, J.H.

    1989-11-14

    This patent describes apparatus for supporting a marine seismic transducer from a vessel. It comprises: an elongated substantially rigid towing arm; a connector means for connecting the transducer to a lower end of the towing arm; a swivel member which is secured to the vessel and is pivotable about a generally horizontal first axis transverse to a length of the vessel; and a support means for pivotally connecting an upper end of the towing arm to the swivel member. The support means being pivotal relative to the swivel member about a second axis transverse to a longitudinal axis of themore » towing arm. The support means being substantially rigid so as to prevent any substantial rotation of the towing arm about its the longitudinal axis.« less

  6. Aspects concerning verification methods and rigidity increment of complex technological systems

    NASA Astrophysics Data System (ADS)

    Casian, M.

    2016-11-01

    Any technological process and technology aims a quality and precise product, something almost impossible without high rigidity machine tools, equipment and components. Therefore, from the design phase, it is very important to create structures and machines with high stiffness characteristics. At the same time, increasing the stiffness should not raise the material costs. Searching this midpoint between high rigidity and minimum expenses leads to investigations and checks in structural components through various methods and techniques and sometimes quite advanced methods. In order to highlight some aspects concerning the significance of the mechanical equipment rigidity, the finite element method and an analytical method based on the use Mathcad software were used, by taking into consideration a subassembly of a grinding machine. Graphical representations were elaborated, offering a more complete image about the stresses and deformations able to affect the considered mechanical subassembly.

  7. Nonlinear vibration of an axially loaded beam carrying rigid bodies

    NASA Astrophysics Data System (ADS)

    Barry, O.

    2016-12-01

    This paper investigates the nonlinear vibration due to mid-plane stretching of an axially loaded simply supported beam carrying multiple rigid masses. Explicit expressions and closed form solutions of both linear and nonlinear analysis of the present vibration problem are presented for the first time. The validity of the analytical model is demonstrated using finite element analysis and via comparison with the result in the literature. Parametric studies are conducted to examine how the nonlinear frequency and frequency response curve are affected by tension, rotational inertia, and number of intermediate rigid bodies.

  8. Shear-induced rigidity in athermal materials

    NASA Astrophysics Data System (ADS)

    Chakraborty, Bulbul; Sarkar, Sumantra

    2014-03-01

    In this talk, we present a minimal model of rigidity and plastic failure in solids whose rigidity emerges directly as a result of applied stresses. Examples include shear-jamming (SJ) in dry grains and discontinuous shear thickening (DST) of dense non-Brownian suspensions. Both SJ and DST states are examples of non-equilibrium, self-assembled structures that have evolved to support the load that created them. These are strongly-interacting systems where the interactions arise primarily from the strict constraints of force and torque balance at the local and global scales. Our model is based on a reciprocal-space picture that strictly enforces the local and global constraints, and is, therefore, best suited to capturing the strong correlations in these non-equilibrium systems. The reciprocal space is a tiling whose edges represent contact forces, and whose faces represent grains. A separation of scale between force fluctuations and displacements of grains is used to represent the positional disorder as quenched randomness on variables in the reciprocal space. Comparing theoretical results to experiments, we will argue that the packing fraction controls the strength of the quenched disorder. Sumantra Sarkar et al, Phys. Rev. Lett. 111, 068301 (2013)

  9. The proton and helium rigidity spectra from 10 to 50 GV

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Cleghorn, T.; Lacy, J. L.; Zipse, J. E.; Daniel, R. R.; Golden, R. L.; Stephens, S. A.

    1978-01-01

    A magnet spectrometer flown from Palestine, Texas, (September 15, 1976) has produced measurements on 150,000 protons and 20,000 helium nuclei covering the rigidity range 10-50 GV. In this interval, the proton spectrum has been fitted to a power law with a spectral index of 2.51 + or - 0.03. Similarly, the helium-nuclei rigidity spectrum can be represented as a power law with an index of 2.61 + or - 0.03.

  10. A geometrically controlled rigidity transition in a model for confluent 3D tissues

    NASA Astrophysics Data System (ADS)

    Merkel, Matthias; Manning, M. Lisa

    2018-02-01

    The origin of rigidity in disordered materials is an outstanding open problem in statistical physics. Previously, a class of 2D cellular models has been shown to undergo a rigidity transition controlled by a mechanical parameter that specifies cell shapes. Here, we generalize this model to 3D and find a rigidity transition that is similarly controlled by the preferred surface area S 0: the model is solid-like below a dimensionless surface area of {s}0\\equiv {S}0/{\\bar{V}}2/3≈ 5.413 with \\bar{V} being the average cell volume, and fluid-like above this value. We demonstrate that, unlike jamming in soft spheres, residual stresses are necessary to create rigidity. These stresses occur precisely when cells are unable to obtain their desired geometry, and we conjecture that there is a well-defined minimal surface area possible for disordered cellular structures. We show that the behavior of this minimal surface induces a linear scaling of the shear modulus with the control parameter at the transition point, which is different from the scaling observed in particulate matter. The existence of such a minimal surface may be relevant for biological tissues and foams, and helps explain why cell shapes are a good structural order parameter for rigidity transitions in biological tissues.

  11. Connect-disconnect coupling for preadjusted rigid shafts

    NASA Technical Reports Server (NTRS)

    Bajkowski, F. W.; Holmberg, A.

    1969-01-01

    Coupling device enables a rigid shaft to be connected to or disconnected from a fixed base without disturbing the point of adjustment of the shaft in a socket or causing the shaft to rotate. The coupling consists of an externally threaded, internally slotted boss extending from the fixed base.

  12. Rigid polyurethane and kenaf core composite foams

    USDA-ARS?s Scientific Manuscript database

    Rigid polyurethane foams are valuable in many construction applications. Kenaf is a bast fiber plant where the surface stem skin provides bast fibers whose strength-to-weight ratio competes with glass fiber. The higher volume product of the kenaf core is an under-investigated area in composite appli...

  13. The treatment of loss of penile rigidity associated with Peyronie's disease.

    PubMed

    Krane, R J

    1996-01-01

    Patients with Peyronie's Disease on occasion present with loss of rigid erections. A full evaluation is required to determine the presence or absence of arterial insufficiency or corporal veno-occlusive dysfunction. Treatment for these patients include intracavernosal pharmacotherapy, a vacuum/constrictor device, venous ligation surgery or a penile prosthesis. Whatever the therapeutic approach, the angulation produced by the Peyronie's plaque must be taken into account. Patients with Peyronie's Disease will present to their physicians with a variety of clinical scenarios. They may merely be concerned with the presence of an asymptomatic penile plaque and will simply require reassurance. More typically, however, penile curvature, pain, and/or difficulty with sexual relations will prompt the desire for medical advice. Treatment of penile pain which usually abates with time and attempts at non surgically treating the Peyronies plaque will not be discussed in this paper. Patients with penile plaque and curvature present in three distinct ways: a. penile rigidity preserved and the ability to continue sexual relations; b, penile rigidity preserved and the inability to continue with sexual relations because of significant angulation; c. the inability to have rigid erections. The patient who is able to continue sexual relations with preserved penile rigidity and the lack of significant penile angulation requires no treatment. However, the patient who has lost his ability to have sexual relations because of significant angulation is a candidate for penile straightening surgery (e.g. graft) (1, 11). It is the last group of patients. Namely those who are not able to maintain penile rigidity because of their Peyronie's Disease that will be addressed in this paper. Patients who present with impotence (i.e. loss of penile rigidity) and Peyronie's disease should be evaluated in a similar manner as patients who present with erectile dysfunction and do not have Peyronie's Disease

  14. Hippo/YAP-mediated rigidity-dependent motor neuron differentiation of human pluripotent stem cells

    NASA Astrophysics Data System (ADS)

    Sun, Yubing; Yong, Koh Meng Aw; Villa-Diaz, Luis G.; Zhang, Xiaoli; Chen, Weiqiang; Philson, Renee; Weng, Shinuo; Xu, Haoxing; Krebsbach, Paul H.; Fu, Jianping

    2014-06-01

    Our understanding of the intrinsic mechanosensitive properties of human pluripotent stem cells (hPSCs), in particular the effects that the physical microenvironment has on their differentiation, remains elusive. Here, we show that neural induction and caudalization of hPSCs can be accelerated by using a synthetic microengineered substrate system consisting of poly(dimethylsiloxane) micropost arrays (PMAs) with tunable mechanical rigidities. The purity and yield of functional motor neurons derived from hPSCs within 23 days of culture using soft PMAs were improved more than fourfold and tenfold, respectively, compared with coverslips or rigid PMAs. Mechanistic studies revealed a multi-targeted mechanotransductive process involving Smad phosphorylation and nucleocytoplasmic shuttling, regulated by rigidity-dependent Hippo/YAP activities and actomyosin cytoskeleton integrity and contractility. Our findings suggest that substrate rigidity is an important biophysical cue influencing neural induction and subtype specification, and that microengineered substrates can thus serve as a promising platform for large-scale culture of hPSCs.

  15. Methadone-induced rigid-chest syndrome after substantial overdose.

    PubMed

    Lynch, Robert E; Hack, Richard A

    2010-07-01

    We report here the case of an infant who developed life-threatening rigid-chest syndrome after receiving an accidental overdose of methadone. The child responded to narcotic reversal. Pediatric physicians should be aware of this possible complication.

  16. Blind source separation based on time-frequency morphological characteristics for rigid acoustic scattering by underwater objects

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Li, Xiukun

    2016-06-01

    Separation of the components of rigid acoustic scattering by underwater objects is essential in obtaining the structural characteristics of such objects. To overcome the problem of rigid structures appearing to have the same spectral structure in the time domain, time-frequency Blind Source Separation (BSS) can be used in combination with image morphology to separate the rigid scattering components of different objects. Based on a highlight model, the separation of the rigid scattering structure of objects with time-frequency distribution is deduced. Using a morphological filter, different characteristics in a Wigner-Ville Distribution (WVD) observed for single auto term and cross terms can be simplified to remove any cross-term interference. By selecting time and frequency points of the auto terms signal, the accuracy of BSS can be improved. An experimental simulation has been used, with changes in the pulse width of the transmitted signal, the relative amplitude and the time delay parameter, in order to analyzing the feasibility of this new method. Simulation results show that the new method is not only able to separate rigid scattering components, but can also separate the components when elastic scattering and rigid scattering exist at the same time. Experimental results confirm that the new method can be used in separating the rigid scattering structure of underwater objects.

  17. Model-based registration of multi-rigid-body for augmented reality

    NASA Astrophysics Data System (ADS)

    Ikeda, Sei; Hori, Hajime; Imura, Masataka; Manabe, Yoshitsugu; Chihara, Kunihiro

    2009-02-01

    Geometric registration between a virtual object and the real space is the most basic problem in augmented reality. Model-based tracking methods allow us to estimate three-dimensional (3-D) position and orientation of a real object by using a textured 3-D model instead of visual marker. However, it is difficult to apply existing model-based tracking methods to the objects that have movable parts such as a display of a mobile phone, because these methods suppose a single, rigid-body model. In this research, we propose a novel model-based registration method for multi rigid-body objects. For each frame, the 3-D models of each rigid part of the object are first rendered according to estimated motion and transformation from the previous frame. Second, control points are determined by detecting the edges of the rendered image and sampling pixels on these edges. Motion and transformation are then simultaneously calculated from distances between the edges and the control points. The validity of the proposed method is demonstrated through experiments using synthetic videos.

  18. Nonlinear mechanics of non-rigid origami: an efficient computational approach

    NASA Astrophysics Data System (ADS)

    Liu, K.; Paulino, G. H.

    2017-10-01

    Origami-inspired designs possess attractive applications to science and engineering (e.g. deployable, self-assembling, adaptable systems). The special geometric arrangement of panels and creases gives rise to unique mechanical properties of origami, such as reconfigurability, making origami designs well suited for tunable structures. Although often being ignored, origami structures exhibit additional soft modes beyond rigid folding due to the flexibility of thin sheets that further influence their behaviour. Actual behaviour of origami structures usually involves significant geometric nonlinearity, which amplifies the influence of additional soft modes. To investigate the nonlinear mechanics of origami structures with deformable panels, we present a structural engineering approach for simulating the nonlinear response of non-rigid origami structures. In this paper, we propose a fully nonlinear, displacement-based implicit formulation for performing static/quasi-static analyses of non-rigid origami structures based on `bar-and-hinge' models. The formulation itself leads to an efficient and robust numerical implementation. Agreement between real models and numerical simulations demonstrates the ability of the proposed approach to capture key features of origami behaviour.

  19. Nonlinear mechanics of non-rigid origami: an efficient computational approach.

    PubMed

    Liu, K; Paulino, G H

    2017-10-01

    Origami-inspired designs possess attractive applications to science and engineering (e.g. deployable, self-assembling, adaptable systems). The special geometric arrangement of panels and creases gives rise to unique mechanical properties of origami, such as reconfigurability, making origami designs well suited for tunable structures. Although often being ignored, origami structures exhibit additional soft modes beyond rigid folding due to the flexibility of thin sheets that further influence their behaviour. Actual behaviour of origami structures usually involves significant geometric nonlinearity, which amplifies the influence of additional soft modes. To investigate the nonlinear mechanics of origami structures with deformable panels, we present a structural engineering approach for simulating the nonlinear response of non-rigid origami structures. In this paper, we propose a fully nonlinear, displacement-based implicit formulation for performing static/quasi-static analyses of non-rigid origami structures based on 'bar-and-hinge' models. The formulation itself leads to an efficient and robust numerical implementation. Agreement between real models and numerical simulations demonstrates the ability of the proposed approach to capture key features of origami behaviour.

  20. Peeling flexible beams in viscous fluids: Rigidity and extensional compliance

    NASA Astrophysics Data System (ADS)

    Dhong, Charles; Fréchette, Joëlle

    2017-01-01

    We describe small angle peeling measurements in completely submerged environments to study the coupling between viscous forces and the mechanical properties of the plates being peeled. During the experiments, the plates resist motion because of lubrication forces while van der Waals forces between the plates and the static surface are negligible. In particular, we study the role played by flexural rigidity in the force-displacement curves and in the energy release rate. We show that the coupling between the viscous forces and the flexural rigidity of the plates dictates the shape and magnitude of the force-displacement curves. We develop simple scaling relationships that combine the lubrication forces with an Euler-Bernoulli beam to extract how the peak force and energy release rates depend on the ratio between rigidity and viscosity, and show good agreement between the predictions and experimental results. We also show that increasing the extensional compliance leads to a decrease in both the force-displacement curve and in the energy release rate. We then demonstrate that this reduction can be interpreted in terms of a stress decay length.

  1. Rheology of multiphase polymer systems using novel "melt rigidity" evaluation approach

    NASA Astrophysics Data System (ADS)

    Kracalik, Milan

    2015-04-01

    Multiphase polymer systems like blends, composites and nanocomposites exhibit complex rheological behaviour due to physical and also possibly chemical interactions between individual phases. Up to now, rheology of heterogeneous polymer systems has been usually described by evaluation of viscosity curve (shear thinning phenomenon), storage modulus curve (formation of secondary plateau) or plotting information about damping behaviour (e.g. Van Gurp-Palmen-plot). On the contrary to evaluation of damping behaviour, "melt rigidity" approach has been introduced for description of physical network of rigid particles in polymer matrix as relation of ∫G'/∫G" over specific frequency range. This approach has been experimentally proved for polymer nanocomposites in order to compare shear flow characteristics with elongational flow field. In this contribution, LDPE-clay nanocomposites with different dispersion grades (physical networks) have been prepared and characterized by both conventional as well as novel "melt rigidity" approach.

  2. Network rigidity and properties of SiO2 and GeO2 glasses under pressure.

    PubMed

    Trachenko, Kostya; Dove, Martin T; Brazhkin, Vadim; El'kin, F S

    2004-09-24

    We report in situ studies of SiO2 glass under pressure and find that temperature-induced densification takes place in a pressure window. To explain this effect, we study how rigidity of glasses changes under pressure, with rigidity percolation affecting the dynamics of local relaxation events. We link rigidity percolation in glasses to other effects, including a large increase of crystallization temperature and logarithmic relaxation under pressure.

  3. Flexible band versus rigid ring annuloplasty for tricuspid regurgitation: a systematic review and meta-analysis.

    PubMed

    Wang, Nelson; Phan, Steven; Tian, David H; Yan, Tristan D; Phan, Kevin

    2017-05-01

    Up to 20% of patients have pre-discharge residual moderate to severe tricuspid regurgitation (TR) after tricuspid repair. Reoperations for recurrent TR carry high mortality rates, which emphasizes the importance of identifying the optimal technique for the surgical management of TR. The present study is a systematic review and meta-analysis that aims to compare short and long term survival and freedom from TR of flexible band ring versus rigid ring for annuloplasty of TR. We conducted a systematic review and meta-analysis of comparative studies to evaluate these procedures. A systematic search of the literature was performed from six electronic databases. Pooled meta-analysis was conducted using odds ratio (OR) and weighted mean difference (WMD). The rates of in-hospital mortality were not different between the two groups, with cumulative rates of 6.9% for flexible band and 7.3% for rigid ring (OR: 0.92; 95% CI: 0.49-1.71). Rates of stroke were also similar with 1.7% of flexible band and 1.3% of rigid rings suffering a perioperative stroke (OR: 1.29; 95% CI: 0.74-2.23). Rigid ring had significantly better freedom from grade ≥2 TR at 5 years (OR: 0.44; 95% CI: 0.20-0.99) and overall (P=0.005). There was no significant difference in overall rates of reoperation (P=0.232) and survival (P=0.086) between flexible band and rigid ring. Both rigid ring and flexible band offer acceptable outcomes for the treatment of TR. Compared to flexible band, rates of TR are stable after rigid ring annuloplasty and long term freedom from TR are superior for rigid ring devices. Large prospective randomized trials are required in order to validate these findings and assess for improvements in patient survival.

  4. A Life Cycle Cost Analysis of Rigid Pavements

    DOT National Transportation Integrated Search

    1999-09-01

    The Texas Department of Transportation (TxDOT)commissioned a research project in 1996, summarized here, to promote life cycle cost analysis of rigid pavements throughout the TxDOT districts by developing a uniform methodology for performing life cycl...

  5. Dielectric elastomer bending tube actuators with rigid electrode structures

    NASA Astrophysics Data System (ADS)

    Wehrheim, F.; Schlaak, H. F.; Meyer, J.-U.

    2010-04-01

    The common approach for dielectric elastomer actuators (DEA) is based on the assumption that compliant electrodes are a fundamental design requirement. For tube-like applications compliant electrodes cause a change of the actuator diameter during actuation and would require additional support-structures. Focused on thinwalled actuator-tube geometries room consumption and radial stabilityr epresent crucial criteria. Following the ambition of maximum functional integration, the concept of using a rigid electrode structure arises. This structure realizes both, actuation and support characteristics. The intended rigid electrode structure is based on a stacked DEA with a non-compressible dielectric. Byactu ation, the displaced dielectric causes an overlap. This overlap serves as an indicator for geometrical limitations and has been used to extract design rules regarding the electrode size, electrode distance and maximum electrode travel. Bycons idering the strain in anydir ection, the mechanical efficiencyhas been used to define further design aspects. To verifyt he theoretic analysis, a test for determination of the compressive stress-strain-characteristics has been applied for different electrode setups. As result the geometrydep ending elastic pressure module has been formulated by implementation of a shape factor. The presented investigations consider exclusive the static behavior of a DEA-setup with rigid electrodes.

  6. Orangutans (Pongo spp.) may prefer tools with rigid properties to flimsy tools.

    PubMed

    Walkup, Kristina R; Shumaker, Robert W; Pruetz, Jill D

    2010-11-01

    Preference for tools with either rigid or flexible properties was explored in orangutans (Pongo spp.) through an extension of D. J. Povinelli, J. E. Reaux, and L. A. Theall's (2000) flimsy-tool problem. Three captive orangutans were presented with three unfamiliar pairs of tools to solve a novel problem. Although each orangutan has spontaneously used tools in the past, the tools presented in this study were novel to the apes. Each pair of tools contained one tool with rigid properties (functional) and one tool with flimsy properties (nonfunctional). Solving the problem required selection of a rigid tool to retrieve a food reward. The functional tool was selected in nearly all trials. Moreover, two of the orangutans demonstrated this within the first test trials with each of the three tool types. Although further research is required to test this statistically, it suggests either a preexisting preference for rigid tools or comprehension of the relevant features required in a tool to solve the task. The results of this study demonstrate that orangutans can recognize, or learn to recognize, relevant tool properties and can choose an appropriate tool to solve a problem. (PsycINFO Database Record (c) 2010 APA, all rights reserved).

  7. Geomagnetic Cutoff Rigidity Computer Program: Theory, Software Description and Example

    NASA Technical Reports Server (NTRS)

    Smart, D. F.; Shea, M. A.

    2001-01-01

    The access of charged particles to the earth from space through the geomagnetic field has been of interest since the discovery of the cosmic radiation. The early cosmic ray measurements found that cosmic ray intensity was ordered by the magnetic latitude and the concept of cutoff rigidity was developed. The pioneering work of Stoermer resulted in the theory of particle motion in the geomagnetic field, but the fundamental mathematical equations developed have 'no solution in closed form'. This difficulty has forced researchers to use the 'brute force' technique of numerical integration of individual trajectories to ascertain the behavior of trajectory families or groups. This requires that many of the trajectories must be traced in order to determine what energy (or rigidity) a charged particle must have to penetrate the magnetic field and arrive at a specified position. It turned out the cutoff rigidity was not a simple quantity but had many unanticipated complexities that required many hundreds if not thousands of individual trajectory calculations to solve. The accurate calculation of particle trajectories in the earth's magnetic field is a fundamental problem that limited the efficient utilization of cosmic ray measurements during the early years of cosmic ray research. As the power of computers has improved over the decades, the numerical integration procedure has grown more tractable, and magnetic field models of increasing accuracy and complexity have been utilized. This report is documentation of a general FORTRAN computer program to trace the trajectory of a charged particle of a specified rigidity from a specified position and direction through a model of the geomagnetic field.

  8. Observation of the Identical Rigidity Dependence of He, C, and O Cosmic Rays at High Rigidities by the Alpha Magnetic Spectrometer on the International Space Station

    NASA Astrophysics Data System (ADS)

    Aguilar, M.; Ali Cavasonza, L.; Alpat, B.; Ambrosi, G.; Arruda, L.; Attig, N.; Aupetit, S.; Azzarello, P.; Bachlechner, A.; Barao, F.; Barrau, A.; Barrin, L.; Bartoloni, A.; Basara, L.; Başeǧmez-du Pree, S.; Battarbee, M.; Battiston, R.; Becker, U.; Behlmann, M.; Beischer, B.; Berdugo, J.; Bertucci, B.; Bindel, K. F.; Bindi, V.; de Boer, W.; Bollweg, K.; Bonnivard, V.; Borgia, B.; Boschini, M. J.; Bourquin, M.; Bueno, E. F.; Burger, J.; Burger, W. J.; Cadoux, F.; Cai, X. D.; Capell, M.; Caroff, S.; Casaus, J.; Castellini, G.; Cervelli, F.; Chae, M. J.; Chang, Y. H.; Chen, A. I.; Chen, G. M.; Chen, H. S.; Cheng, L.; Chou, H. Y.; Choumilov, E.; Choutko, V.; Chung, C. H.; Clark, C.; Clavero, R.; Coignet, G.; Consolandi, C.; Contin, A.; Corti, C.; Creus, W.; Crispoltoni, M.; Cui, Z.; Dadzie, K.; Dai, Y. M.; Datta, A.; Delgado, C.; Della Torre, S.; Demakov, O.; Demirköz, M. B.; Derome, L.; Di Falco, S.; Dimiccoli, F.; Díaz, C.; von Doetinchem, P.; Dong, F.; Donnini, F.; Duranti, M.; D'Urso, D.; Egorov, A.; Eline, A.; Eronen, T.; Feng, J.; Fiandrini, E.; Fisher, P.; Formato, V.; Galaktionov, Y.; Gallucci, G.; García-López, R. J.; Gargiulo, C.; Gast, H.; Gebauer, I.; Gervasi, M.; Ghelfi, A.; Giovacchini, F.; Gómez-Coral, D. M.; Gong, J.; Goy, C.; Grabski, V.; Grandi, D.; Graziani, M.; Guo, K. H.; Haino, S.; Han, K. C.; He, Z. H.; Heil, M.; Hoffman, J.; Hsieh, T. H.; Huang, H.; Huang, Z. C.; Huh, C.; Incagli, M.; Ionica, M.; Jang, W. Y.; Jia, Yi; Jinchi, H.; Kang, S. C.; Kanishev, K.; Khiali, B.; Kim, G. N.; Kim, K. S.; Kirn, Th.; Konak, C.; Kounina, O.; Kounine, A.; Koutsenko, V.; Kulemzin, A.; La Vacca, G.; Laudi, E.; Laurenti, G.; Lazzizzera, I.; Lebedev, A.; Lee, H. T.; Lee, S. C.; Leluc, C.; Li, H. S.; Li, J. Q.; Li, Q.; Li, T. X.; Li, Y.; Li, Z. H.; Li, Z. Y.; Lim, S.; Lin, C. H.; Lipari, P.; Lippert, T.; Liu, D.; Liu, Hu; Lordello, V. D.; Lu, S. Q.; Lu, Y. S.; Luebelsmeyer, K.; Luo, F.; Luo, J. Z.; Lyu, S. S.; Machate, F.; Mañá, C.; Marín, J.; Martin, T.; Martínez, G.; Masi, N.; Maurin, D.; Menchaca-Rocha, A.; Meng, Q.; Mikuni, V. M.; Mo, D. C.; Mott, P.; Nelson, T.; Ni, J. Q.; Nikonov, N.; Nozzoli, F.; Oliva, A.; Orcinha, M.; Palmonari, F.; Palomares, C.; Paniccia, M.; Pauluzzi, M.; Pensotti, S.; Perrina, C.; Phan, H. D.; Picot-Clemente, N.; Pilo, F.; Pizzolotto, C.; Plyaskin, V.; Pohl, M.; Poireau, V.; Quadrani, L.; Qi, X. M.; Qin, X.; Qu, Z. Y.; Räihä, T.; Rancoita, P. G.; Rapin, D.; Ricol, J. S.; Rosier-Lees, S.; Rozhkov, A.; Rozza, D.; Sagdeev, R.; Schael, S.; Schmidt, S. M.; Schulz von Dratzig, A.; Schwering, G.; Seo, E. S.; Shan, B. S.; Shi, J. Y.; Siedenburg, T.; Son, D.; Song, J. W.; Tacconi, M.; Tang, X. W.; Tang, Z. C.; Tescaro, D.; Ting, Samuel C. C.; Ting, S. M.; Tomassetti, N.; Torsti, J.; Türkoǧlu, C.; Urban, T.; Vagelli, V.; Valente, E.; Valtonen, E.; Vázquez Acosta, M.; Vecchi, M.; Velasco, M.; Vialle, J. P.; Vitale, V.; Vitillo, S.; Wang, L. Q.; Wang, N. H.; Wang, Q. L.; Wang, X.; Wang, X. Q.; Wang, Z. X.; Wei, C. C.; Weng, Z. L.; Whitman, K.; Wu, H.; Wu, X.; Xiong, R. Q.; Xu, W.; Yan, Q.; Yang, J.; Yang, M.; Yang, Y.; Yi, H.; Yu, Y. J.; Yu, Z. Q.; Zannoni, M.; Zeissler, S.; Zhang, C.; Zhang, F.; Zhang, J.; Zhang, J. H.; Zhang, S. W.; Zhang, Z.; Zheng, Z. M.; Zhuang, H. L.; Zhukov, V.; Zichichi, A.; Zimmermann, N.; Zuccon, P.; AMS Collaboration

    2017-12-01

    We report the observation of new properties of primary cosmic rays He, C, and O measured in the rigidity (momentum/charge) range 2 GV to 3 TV with 90 ×106 helium, 8.4 ×106 carbon, and 7.0 ×106 oxygen nuclei collected by the Alpha Magnetic Spectrometer (AMS) during the first five years of operation. Above 60 GV, these three spectra have identical rigidity dependence. They all deviate from a single power law above 200 GV and harden in an identical way.

  9. An adaptive model approach for quantitative wrist rigidity evaluation during deep brain stimulation surgery.

    PubMed

    Assis, Sofia; Costa, Pedro; Rosas, Maria Jose; Vaz, Rui; Silva Cunha, Joao Paulo

    2016-08-01

    Intraoperative evaluation of the efficacy of Deep Brain Stimulation includes evaluation of the effect on rigidity. A subjective semi-quantitative scale is used, dependent on the examiner perception and experience. A system was proposed previously, aiming to tackle this subjectivity, using quantitative data and providing real-time feedback of the computed rigidity reduction, hence supporting the physician decision. This system comprised of a gyroscope-based motion sensor in a textile band, placed in the patients hand, which communicated its measurements to a laptop. The latter computed a signal descriptor from the angular velocity of the hand during wrist flexion in DBS surgery. The first approach relied on using a general rigidity reduction model, regardless of the initial severity of the symptom. Thus, to enhance the performance of the previously presented system, we aimed to develop models for high and low baseline rigidity, according to the examiner assessment before any stimulation. This would allow a more patient-oriented approach. Additionally, usability was improved by having in situ processing in a smartphone, instead of a computer. Such system has shown to be reliable, presenting an accuracy of 82.0% and a mean error of 3.4%. Relatively to previous results, the performance was similar, further supporting the importance of considering the cogwheel rigidity to better infer about the reduction in rigidity. Overall, we present a simple, wearable, mobile system, suitable for intra-operatory conditions during DBS, supporting a physician in decision-making when setting stimulation parameters.

  10. Nonlinear optical properties of rigid-rod polymers

    NASA Technical Reports Server (NTRS)

    Trimmer, Mark S.; Wang, Ying

    1992-01-01

    The purpose of this research project was to integrate enhanced third order nonlinear optical (NLO) properties, especially high x(exp (3)) (greater than 10(exp -8) esu), into Maxdem's novel conjugated rigid-rod polymers while retaining their desirable processing, mechanical, and thermal properties. This work primarily involved synthetic approaches to optimized materials.

  11. Study of sealing practices for rigid pavement joints.

    DOT National Transportation Integrated Search

    1971-01-01

    The joint sealing materials and the rigid pavement joint sealing practices employed by Virginia and other highway agencies were studied. The studies showed that Virginia's sealant and joint designs were in need of updating and that higher quality pou...

  12. Tin monochalcogenide heterostructures as mechanically rigid infrared band gap semiconductors

    NASA Astrophysics Data System (ADS)

    Özçelik, V. Ongun; Fathi, Mohammad; Azadani, Javad G.; Low, Tony

    2018-05-01

    Based on first-principles density functional calculations, we show that SnS and SnSe layers can form mechanically rigid heterostructures with the constituent puckered or buckled monolayers. Due to the strong interlayer coupling, the electronic wave functions of the conduction and valence band edges are delocalized across the heterostructure. The resultant band gaps of the heterostructures reside in the infrared region. With strain engineering, the heterostructure band gap undergoes a transition from indirect to direct in the puckered phase. Our results show that there is a direct correlation between the electronic wave function and the mechanical rigidity of the layered heterostructure.

  13. Tolman lengths and rigidity constants of multicomponent fluids: Fundamental theory and numerical examples

    NASA Astrophysics Data System (ADS)

    Aasen, Ailo; Blokhuis, Edgar M.; Wilhelmsen, Øivind

    2018-05-01

    The curvature dependence of the surface tension can be described by the Tolman length (first-order correction) and the rigidity constants (second-order corrections) through the Helfrich expansion. We present and explain the general theory for this dependence for multicomponent fluids and calculate the Tolman length and rigidity constants for a hexane-heptane mixture by use of square gradient theory. We show that the Tolman length of multicomponent fluids is independent of the choice of dividing surface and present simple formulae that capture the change in the rigidity constants for different choices of dividing surface. For multicomponent fluids, the Tolman length, the rigidity constants, and the accuracy of the Helfrich expansion depend on the choice of path in composition and pressure space along which droplets and bubbles are considered. For the hexane-heptane mixture, we find that the most accurate choice of path is the direction of constant liquid-phase composition. For this path, the Tolman length and rigidity constants are nearly linear in the mole fraction of the liquid phase, and the Helfrich expansion represents the surface tension of hexane-heptane droplets and bubbles within 0.1% down to radii of 3 nm. The presented framework is applicable to a wide range of fluid mixtures and can be used to accurately represent the surface tension of nanoscopic bubbles and droplets.

  14. Computing the Free Energy along a Reaction Coordinate Using Rigid Body Dynamics.

    PubMed

    Tao, Peng; Sodt, Alexander J; Shao, Yihan; König, Gerhard; Brooks, Bernard R

    2014-10-14

    The calculations of potential of mean force along complex chemical reactions or rare events pathways are of great interest because of their importance for many areas in chemistry, molecular biology, and material science. The major difficulty for free energy calculations comes from the great computational cost for adequate sampling of the system in high-energy regions, especially close to the reaction transition state. Here, we present a method, called FEG-RBD, in which the free energy gradients were obtained from rigid body dynamics simulations. Then the free energy gradients were integrated along a reference reaction pathway to calculate free energy profiles. In a given system, the reaction coordinates defining a subset of atoms (e.g., a solute, or the quantum mechanics (QM) region of a quantum mechanics/molecular mechanics simulation) are selected to form a rigid body during the simulation. The first-order derivatives (gradients) of the free energy with respect to the reaction coordinates are obtained through the integration of constraint forces within the rigid body. Each structure along the reference reaction path is separately subjected to such a rigid body simulation. The individual free energy gradients are integrated along the reference pathway to obtain the free energy profile. Test cases provided demonstrate both the strengths and weaknesses of the FEG-RBD method. The most significant benefit of this method comes from the fast convergence rate of the free energy gradient using rigid-body constraints instead of restraints. A correction to the free energy due to approximate relaxation of the rigid-body constraint is estimated and discussed. A comparison with umbrella sampling using a simple test case revealed the improved sampling efficiency of FEG-RBD by a factor of 4 on average. The enhanced efficiency makes this method effective for calculating the free energy of complex chemical reactions when the reaction coordinate can be unambiguously defined by a

  15. Computing the Free Energy along a Reaction Coordinate Using Rigid Body Dynamics

    PubMed Central

    2015-01-01

    The calculations of potential of mean force along complex chemical reactions or rare events pathways are of great interest because of their importance for many areas in chemistry, molecular biology, and material science. The major difficulty for free energy calculations comes from the great computational cost for adequate sampling of the system in high-energy regions, especially close to the reaction transition state. Here, we present a method, called FEG-RBD, in which the free energy gradients were obtained from rigid body dynamics simulations. Then the free energy gradients were integrated along a reference reaction pathway to calculate free energy profiles. In a given system, the reaction coordinates defining a subset of atoms (e.g., a solute, or the quantum mechanics (QM) region of a quantum mechanics/molecular mechanics simulation) are selected to form a rigid body during the simulation. The first-order derivatives (gradients) of the free energy with respect to the reaction coordinates are obtained through the integration of constraint forces within the rigid body. Each structure along the reference reaction path is separately subjected to such a rigid body simulation. The individual free energy gradients are integrated along the reference pathway to obtain the free energy profile. Test cases provided demonstrate both the strengths and weaknesses of the FEG-RBD method. The most significant benefit of this method comes from the fast convergence rate of the free energy gradient using rigid-body constraints instead of restraints. A correction to the free energy due to approximate relaxation of the rigid-body constraint is estimated and discussed. A comparison with umbrella sampling using a simple test case revealed the improved sampling efficiency of FEG-RBD by a factor of 4 on average. The enhanced efficiency makes this method effective for calculating the free energy of complex chemical reactions when the reaction coordinate can be unambiguously defined by a

  16. Measurement of dowel bar response in rigid pavement

    DOT National Transportation Integrated Search

    1999-01-01

    The effectiveness of load transfer between adjacent slabs is an important component of long term rigid pavement performance. When load transfer is minimal or non-existent, concrete slabs must carry the full weight of truck axles across their entire l...

  17. Miniscrew biomechanics: Guidelines for the use of rigid indirect anchorage mechanics.

    PubMed

    Baumgaertel, Sebastian; Jones, Clark L; Unal, Mustafa

    2017-09-01

    Indirect anchorage is an established form of anchorage provided by orthodontic miniscrews. Although there are different ways to set up the mechanics, rigid indirect anchorage offers the greatest biomechanical versatility but is more difficult to install than conventional, nonrigid indirect anchorage or direct anchorage. The purpose of this article was to introduce readers to the concept of rigid indirect anchorage and provide guidelines as to its use. Copyright © 2017 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  18. Thermal Noise Limit in Frequency Stabilization of Lasers with Rigid Cavities

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Kemery, Amy; Camp, Jordan

    2005-01-01

    We evaluated thermal noise (Brownian motion) in a rigid reference cavity Used for frequency stabilization of lasers, based on the mechanical loss of cavity materials and the numerical analysis of the mirror-spacer mechanics with the direct application of the fluctuation dissipation theorem. This noise sets a fundamental limit for the frequency stability achieved with a rigid frequency-reference cavity of order 1 Hz/rtHz at 10mHz at room temperature. This level coincides with the world-highest level stabilization results.

  19. Advanced Pavement Design: Finite Element Modeling for Rigid Pavement Joints, Report II: Model Development

    DOT National Transportation Integrated Search

    1998-03-01

    The contribution of a cement-stabilized base course to the strength of the rigid pavement structure is poorly understood. The objective of this research was to obtain data on the response of the rigid pavement slab-joint-foundation system by conducti...

  20. MASPROP- MASS PROPERTIES OF A RIGID STRUCTURE

    NASA Technical Reports Server (NTRS)

    Hull, R. A.

    1994-01-01

    The computer program MASPROP was developed to rapidly calculate the mass properties of complex rigid structural systems. This program's basic premise is that complex systems can be adequately described by a combination of basic elementary structural shapes. Thirteen widely used basic structural shapes are available in this program. They are as follows: Discrete Mass, Cylinder, Truncated Cone, Torus, Beam (arbitrary cross section), Circular Rod (arbitrary cross section), Spherical Segment, Sphere, Hemisphere, Parallelepiped, Swept Trapezoidal Panel, Symmetric Trapezoidal Panels, and a Curved Rectangular Panel. MASPROP provides a designer with a simple technique that requires minimal input to calculate the mass properties of a complex rigid structure and should be useful in any situation where one needs to calculate the center of gravity and moments of inertia of a complex structure. Rigid body analysis is used to calculate mass properties. Mass properties are calculated about component axes that have been rotated to be parallel to the system coordinate axes. Then the system center of gravity is calculated and the mass properties are transferred to axes through the system center of gravity by using the parallel axis theorem. System weight, moments of inertia about the system origin, and the products of inertia about the system center of mass are calculated and printed. From the information about the system center of mass the principal axes of the system and the moments of inertia about them are calculated and printed. The only input required is simple geometric data describing the size and location of each element and the respective material density or weight of each element. This program is written in FORTRAN for execution on a CDC 6000 series computer with a central memory requirement of approximately 62K (octal) of 60 bit words. The development of this program was completed in 1978.

  1. Rigidity Sensing Explained by Active Matter Theory

    PubMed Central

    Marcq, Philippe; Yoshinaga, Natsuhiko; Prost, Jacques

    2011-01-01

    The magnitude of traction forces exerted by living animal cells on their environment is a monotonically increasing and approximately sigmoidal function of the stiffness of the external medium. We rationalize this observation using active matter theory, and propose that adaptation to substrate rigidity results from an interplay between passive elasticity and active contractility. PMID:21943439

  2. Adsorption of asymmetric rigid rods or heteronuclear diatomic moleculeson homogeneous surfaces

    NASA Astrophysics Data System (ADS)

    Engl, W.; Courbin, L.; Panizza, P.

    2004-10-01

    We treat the adsorption on homogeneous surfaces of asymmetric rigid rods (like for instance heteronuclear diatomic molecules). We show that the n→0 vector spin formalism is well suited to describe such a problem. We establish an isomorphism between the coupling constants of the magnetic Hamiltonian and the adsorption parameters of the rigid rods. By solving this Hamiltonian within a mean-field approximation, we obtain analytical expressions for the densities of the different rod’s configurations, both isotherm and isobar adsorptions curves. The most probable configurations of the molecules (normal or parallel to the surface) which depends on temperature and energy parameters are summarized in a diagram. We derive that the variation of Qv , the heat of adsorption at constant volume, with the temperature is a direct signature of the adsorbed molecules configuration change. We show that this formalism can be generalized to more complicated problems such as for instance the adsorption of symmetric and asymmetric rigid rods mixtures in the presence or not of interactions.

  3. Compliant mechanism road bicycle brake: a rigid-body replacement case study

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

    Olsen, Brian M; Howell, Larry L; Magleby, Spencer P

    2011-01-19

    The design of high-performance bicycle brakes is complicated by the competing design objectives of increased performance and low weight. But this challenge also provides a good case study to demonstrate the design of compliant mechanisms to replace current rigid-link mechanisms. This paper briefly reviews current road brake designs, demonstrates the use of rigid-body replacement synthesis to design a compliant mechanism, and illustrates the combination of compliant mechanism design tools. The resulting concept was generated from the modified dual-pivot brake design and is a partially compliant mechanism where one pin has the dual role of a joint and a mounting pin.more » The pseudo-rigid-body model, finite element analysis, and optimization algorithms are used to generate design dimensions, and designs are considered for both titanium and E-glass flexures. The resulting design has the potential of reducing the part count and overall weight while maintaining a performance similar to the benchmark.« less

  4. Bending of an Aspirated Pin During Rigid Bronchoscopy: Safeguards and Pitfalls.

    PubMed

    Elsayed, Abdelrahman A A; Mansour, Albaraa A; Amin, Ahmed A A; Ahmed, Mohsen S M

    2018-04-13

    Pin aspiration is a common problem in Muslim countries, where many women wear veils (hijab). This condition is usually treated using either a rigid or a flexible bronchoscope, and yet occasionally requires surgical approach. Pin bending may be necessary to extract impacted pins during the therapeutic rigid bronchoscopy. Medical records of patients who had pins extracted with a bending technique during the period from January 2012 to December 2016 in 1 institution were analyzed. Information on intraoperative and postoperative complications was collected. Between 2012 and 2016, 315 rigid bronchoscopies were performed for pin extraction; in 38 cases, bending of the pin was required for the extraction because they were in a position that did not allow simple extraction. The procedure was successful in cases and there were no major complications. The extraction of visible, distally located or impacted pins can be safely performed by experienced bronchoscopists using the bending technique. Some safeguards and pitfalls must be noted to ensure maximum safety.

  5. Observation of the Identical Rigidity Dependence of He, C, and O Cosmic Rays at High Rigidities by the Alpha Magnetic Spectrometer on the International Space Station.

    PubMed

    Aguilar, M; Ali Cavasonza, L; Alpat, B; Ambrosi, G; Arruda, L; Attig, N; Aupetit, S; Azzarello, P; Bachlechner, A; Barao, F; Barrau, A; Barrin, L; Bartoloni, A; Basara, L; Başeğmez-du Pree, S; Battarbee, M; Battiston, R; Becker, U; Behlmann, M; Beischer, B; Berdugo, J; Bertucci, B; Bindel, K F; Bindi, V; de Boer, W; Bollweg, K; Bonnivard, V; Borgia, B; Boschini, M J; Bourquin, M; Bueno, E F; Burger, J; Burger, W J; Cadoux, F; Cai, X D; Capell, M; Caroff, S; Casaus, J; Castellini, G; Cervelli, F; Chae, M J; Chang, Y H; Chen, A I; Chen, G M; Chen, H S; Cheng, L; Chou, H Y; Choumilov, E; Choutko, V; Chung, C H; Clark, C; Clavero, R; Coignet, G; Consolandi, C; Contin, A; Corti, C; Creus, W; Crispoltoni, M; Cui, Z; Dadzie, K; Dai, Y M; Datta, A; Delgado, C; Della Torre, S; Demakov, O; Demirköz, M B; Derome, L; Di Falco, S; Dimiccoli, F; Díaz, C; von Doetinchem, P; Dong, F; Donnini, F; Duranti, M; D'Urso, D; Egorov, A; Eline, A; Eronen, T; Feng, J; Fiandrini, E; Fisher, P; Formato, V; Galaktionov, Y; Gallucci, G; García-López, R J; Gargiulo, C; Gast, H; Gebauer, I; Gervasi, M; Ghelfi, A; Giovacchini, F; Gómez-Coral, D M; Gong, J; Goy, C; Grabski, V; Grandi, D; Graziani, M; Guo, K H; Haino, S; Han, K C; He, Z H; Heil, M; Hoffman, J; Hsieh, T H; Huang, H; Huang, Z C; Huh, C; Incagli, M; Ionica, M; Jang, W Y; Jia, Yi; Jinchi, H; Kang, S C; Kanishev, K; Khiali, B; Kim, G N; Kim, K S; Kirn, Th; Konak, C; Kounina, O; Kounine, A; Koutsenko, V; Kulemzin, A; La Vacca, G; Laudi, E; Laurenti, G; Lazzizzera, I; Lebedev, A; Lee, H T; Lee, S C; Leluc, C; Li, H S; Li, J Q; Li, Q; Li, T X; Li, Y; Li, Z H; Li, Z Y; Lim, S; Lin, C H; Lipari, P; Lippert, T; Liu, D; Liu, Hu; Lordello, V D; Lu, S Q; Lu, Y S; Luebelsmeyer, K; Luo, F; Luo, J Z; Lyu, S S; Machate, F; Mañá, C; Marín, J; Martin, T; Martínez, G; Masi, N; Maurin, D; Menchaca-Rocha, A; Meng, Q; Mikuni, V M; Mo, D C; Mott, P; Nelson, T; Ni, J Q; Nikonov, N; Nozzoli, F; Oliva, A; Orcinha, M; Palmonari, F; Palomares, C; Paniccia, M; Pauluzzi, M; Pensotti, S; Perrina, C; Phan, H D; Picot-Clemente, N; Pilo, F; Pizzolotto, C; Plyaskin, V; Pohl, M; Poireau, V; Quadrani, L; Qi, X M; Qin, X; Qu, Z Y; Räihä, T; Rancoita, P G; Rapin, D; Ricol, J S; Rosier-Lees, S; Rozhkov, A; Rozza, D; Sagdeev, R; Schael, S; Schmidt, S M; Schulz von Dratzig, A; Schwering, G; Seo, E S; Shan, B S; Shi, J Y; Siedenburg, T; Son, D; Song, J W; Tacconi, M; Tang, X W; Tang, Z C; Tescaro, D; Ting, Samuel C C; Ting, S M; Tomassetti, N; Torsti, J; Türkoğlu, C; Urban, T; Vagelli, V; Valente, E; Valtonen, E; Vázquez Acosta, M; Vecchi, M; Velasco, M; Vialle, J P; Vitale, V; Vitillo, S; Wang, L Q; Wang, N H; Wang, Q L; Wang, X; Wang, X Q; Wang, Z X; Wei, C C; Weng, Z L; Whitman, K; Wu, H; Wu, X; Xiong, R Q; Xu, W; Yan, Q; Yang, J; Yang, M; Yang, Y; Yi, H; Yu, Y J; Yu, Z Q; Zannoni, M; Zeissler, S; Zhang, C; Zhang, F; Zhang, J; Zhang, J H; Zhang, S W; Zhang, Z; Zheng, Z M; Zhuang, H L; Zhukov, V; Zichichi, A; Zimmermann, N; Zuccon, P

    2017-12-22

    We report the observation of new properties of primary cosmic rays He, C, and O measured in the rigidity (momentum/charge) range 2 GV to 3 TV with 90×10^{6} helium, 8.4×10^{6} carbon, and 7.0×10^{6} oxygen nuclei collected by the Alpha Magnetic Spectrometer (AMS) during the first five years of operation. Above 60 GV, these three spectra have identical rigidity dependence. They all deviate from a single power law above 200 GV and harden in an identical way.

  6. Fractal rigidity in migraine

    NASA Astrophysics Data System (ADS)

    Latka, Miroslaw; Glaubic-Latka, Marta; Latka, Dariusz; West, Bruce J.

    2004-04-01

    We study the middle cerebral artery blood flow velocity (MCAfv) in humans using transcranial Doppler ultrasonography (TCD). Scaling properties of time series of the axial flow velocity averaged over a cardiac beat interval may be characterized by two exponents. The short time scaling exponent (STSE) determines the statistical properties of fluctuations of blood flow velocities in short-time intervals while the Hurst exponent describes the long-term fractal properties. In many migraineurs the value of the STSE is significantly reduced and may approach that of the Hurst exponent. This change in dynamical properties reflects the significant loss of short-term adaptability and the overall hyperexcitability of the underlying cerebral blood flow control system. We call this effect fractal rigidity.

  7. Rigid collapsible dish structure

    NASA Technical Reports Server (NTRS)

    Palmer, William B. (Inventor); Giebler, Martin M. (Inventor)

    1982-01-01

    A collapsible dish structure composed of a plurality of rows of rigid radial petal assemblies concentric with the axis of the dish. The petal assemblies consist of a center petal and two side petals, the center petal hinged on an axis tangent to a circle concentric with the axis of the dish and the side petals hinged to the center petal at their mating edge. The center petal is foldable inwardly and the side petals rotate about their hinges such that the collapsed dish structure occupies a much smaller volume than the deployed dish. Means of controlling the shape of the dish to compensate for differential expansion of the deployed dish are also provided.

  8. Deformable image registration with local rigidity constraints for cone-beam CT-guided spine surgery

    NASA Astrophysics Data System (ADS)

    Reaungamornrat, S.; Wang, A. S.; Uneri, A.; Otake, Y.; Khanna, A. J.; Siewerdsen, J. H.

    2014-07-01

    Image-guided spine surgery (IGSS) is associated with reduced co-morbidity and improved surgical outcome. However, precise localization of target anatomy and adjacent nerves and vessels relative to planning information (e.g., device trajectories) can be challenged by anatomical deformation. Rigid registration alone fails to account for deformation associated with changes in spine curvature, and conventional deformable registration fails to account for rigidity of the vertebrae, causing unrealistic distortions in the registered image that can confound high-precision surgery. We developed and evaluated a deformable registration method capable of preserving rigidity of bones while resolving the deformation of surrounding soft tissue. The method aligns preoperative CT to intraoperative cone-beam CT (CBCT) using free-form deformation (FFD) with constraints on rigid body motion imposed according to a simple intensity threshold of bone intensities. The constraints enforced three properties of a rigid transformation—namely, constraints on affinity (AC), orthogonality (OC), and properness (PC). The method also incorporated an injectivity constraint (IC) to preserve topology. Physical experiments involving phantoms, an ovine spine, and a human cadaver as well as digital simulations were performed to evaluate the sensitivity to registration parameters, preservation of rigid body morphology, and overall registration accuracy of constrained FFD in comparison to conventional unconstrained FFD (uFFD) and Demons registration. FFD with orthogonality and injectivity constraints (denoted FFD+OC+IC) demonstrated improved performance compared to uFFD and Demons. Affinity and properness constraints offered little or no additional improvement. The FFD+OC+IC method preserved rigid body morphology at near-ideal values of zero dilatation ({ D} = 0.05, compared to 0.39 and 0.56 for uFFD and Demons, respectively) and shear ({ S} = 0.08, compared to 0.36 and 0.44 for uFFD and Demons

  9. Handedness in shearing auxetics creates rigid and compliant structures

    NASA Astrophysics Data System (ADS)

    Lipton, Jeffrey Ian; MacCurdy, Robert; Manchester, Zachary; Chin, Lillian; Cellucci, Daniel; Rus, Daniela

    2018-05-01

    In nature, repeated base units produce handed structures that selectively bond to make rigid or compliant materials. Auxetic tilings are scale-independent frameworks made from repeated unit cells that expand under tension. We discovered how to produce handedness in auxetic unit cells that shear as they expand by changing the symmetries and alignments of auxetic tilings. Using the symmetry and alignment rules that we developed, we made handed shearing auxetics that tile planes, cylinders, and spheres. By compositing the handed shearing auxetics in a manner inspired by keratin and collagen, we produce both compliant structures that expand while twisting and deployable structures that can rigidly lock. This work opens up new possibilities in designing chemical frameworks, medical devices like stents, robotic systems, and deployable engineering structures.

  10. 40 CFR 156.146 - Residue removal instructions for nonrefillable containers-rigid containers with dilutable...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... product packaged in a rigid nonrefillable container must include the following residue removal... dilutable pesticide product packaged in rigid nonrefillable containers must include one of the following sets of instructions. (1) For liquid dilutable pesticide products in containers small enough to shake...

  11. Uncertain dynamic analysis for rigid-flexible mechanisms with random geometry and material properties

    NASA Astrophysics Data System (ADS)

    Wu, Jinglai; Luo, Zhen; Zhang, Nong; Zhang, Yunqing; Walker, Paul D.

    2017-02-01

    This paper proposes an uncertain modelling and computational method to analyze dynamic responses of rigid-flexible multibody systems (or mechanisms) with random geometry and material properties. Firstly, the deterministic model for the rigid-flexible multibody system is built with the absolute node coordinate formula (ANCF), in which the flexible parts are modeled by using ANCF elements, while the rigid parts are described by ANCF reference nodes (ANCF-RNs). Secondly, uncertainty for the geometry of rigid parts is expressed as uniform random variables, while the uncertainty for the material properties of flexible parts is modeled as a continuous random field, which is further discretized to Gaussian random variables using a series expansion method. Finally, a non-intrusive numerical method is developed to solve the dynamic equations of systems involving both types of random variables, which systematically integrates the deterministic generalized-α solver with Latin Hypercube sampling (LHS) and Polynomial Chaos (PC) expansion. The benchmark slider-crank mechanism is used as a numerical example to demonstrate the characteristics of the proposed method.

  12. Rigidity of poly-L-glutamic acid scaffolds: Influence of secondary and supramolecular structure

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

    Nickels, Jonathan D.; Perticaroli, Stefania; Ehlers, Georg

    Poly-L-glutamic acid (PGA) is a widely used biomaterial, with applications ranging from drug delivery and biological glues to food products and as a tissue engineering scaffold. A biodegradable material with flexible conjugation functional groups, tunable secondary structure, and mechanical properties, PGA has potential as a tunable matrix material in mechanobiology. Some recent studies in proteins connecting dynamics, nanometer length scale rigidity, and secondary structure suggest a new point of view from which to analyze and develop this promising material. Our paper characterizes the structure, topology, and rigidity properties of PGA prepared with different molecular weights and secondary structures through variousmore » techniques including scanning electron microscopy, FTIR, light, and neutron scattering spectroscopy. On the length scale of a few nanometers, rigidity is determined by hydrogen bonding interactions in the presence of neutral species and by electrostatic interactions when the polypeptide is negatively charged. Finally, when probed over hundreds of nanometers, the rigidity of these materials is modified by long range intermolecular interactions that are introduced by the supramolecular structure.« less

  13. Weak completions, bornologies and rigid cohomology

    NASA Astrophysics Data System (ADS)

    Cortiñas, Guillermo; Cuntz, Joachim; Meyer, Ralf; Tamme, Georg

    2018-07-01

    Let V be a complete discrete valuation ring with residue field k of positive characteristic and with fraction field K of characteristic 0. We clarify the analysis behind the Monsky-Washnitzer completion of a commutative V-algebra using completions of bornological V-algebras. This leads us to a functorial chain complex for a finitely generated commutative algebra over the residue field k that computes its rigid cohomology in the sense of Berthelot.

  14. Numerical Simulation of Dry Granular Flow Impacting a Rigid Wall Using the Discrete Element Method

    PubMed Central

    Wu, Fengyuan; Fan, Yunyun; Liang, Li; Wang, Chao

    2016-01-01

    This paper presents a clump model based on Discrete Element Method. The clump model was more close to the real particle than a spherical particle. Numerical simulations of several tests of dry granular flow impacting a rigid wall flowing in an inclined chute have been achieved. Five clump models with different sphericity have been used in the simulations. By comparing the simulation results with the experimental results of normal force on the rigid wall, a clump model with better sphericity was selected to complete the following numerical simulation analysis and discussion. The calculation results of normal force showed good agreement with the experimental results, which verify the effectiveness of the clump model. Then, total normal force and bending moment of the rigid wall and motion process of the granular flow were further analyzed. Finally, comparison analysis of the numerical simulations using the clump model with different grain composition was obtained. By observing normal force on the rigid wall and distribution of particle size at the front of the rigid wall at the final state, the effect of grain composition on the force of the rigid wall has been revealed. It mainly showed that, with the increase of the particle size, the peak force at the retaining wall also increase. The result can provide a basis for the research of relevant disaster and the design of protective structures. PMID:27513661

  15. Gaussian Curvature as an Identifier of Shell Rigidity

    NASA Astrophysics Data System (ADS)

    Harutyunyan, Davit

    2017-11-01

    In the paper we deal with shells with non-zero Gaussian curvature. We derive sharp Korn's first (linear geometric rigidity estimate) and second inequalities on that kind of shell for zero or periodic Dirichlet, Neumann, and Robin type boundary conditions. We prove that if the Gaussian curvature is positive, then the optimal constant in the first Korn inequality scales like h, and if the Gaussian curvature is negative, then the Korn constant scales like h 4/3, where h is the thickness of the shell. These results have a classical flavour in continuum mechanics, in particular shell theory. The Korn first inequalities are the linear version of the famous geometric rigidity estimate by Friesecke et al. for plates in Arch Ration Mech Anal 180(2):183-236, 2006 (where they show that the Korn constant in the nonlinear Korn's first inequality scales like h 2), extended to shells with nonzero curvature. We also recover the uniform Korn-Poincaré inequality proven for "boundary-less" shells by Lewicka and Müller in Annales de l'Institute Henri Poincare (C) Non Linear Anal 28(3):443-469, 2011 in the setting of our problem. The new estimates can also be applied to find the scaling law for the critical buckling load of the shell under in-plane loads as well as to derive energy scaling laws in the pre-buckled regime. The exponents 1 and 4/3 in the present work appear for the first time in any sharp geometric rigidity estimate.

  16. Herbal Prescriptions and Medicinal Herbs for Parkinson-Related Rigidity in Korean Medicine: Identification of Candidates Using Text Mining.

    PubMed

    Park, So Hyun; Hwang, Min Seob; Park, Hye Jin; Shin, Hwa Kyoung; Baek, Jin Ung; Choi, Byung Tae

    2018-03-27

    Dongeuibogam (DongYiBaoGian), one of the most important books in Korean medicine, comprises a comprehensive summary of all traditional medicines of North-East Asia before the 17th century. This medicinal literature was mined to establish a list of candidate herbs to treat Parkinson-related rigidity. A systematic search for terms describing Parkinson-related rigidity and candidate prescriptions for the treatment of Parkinson-related rigidity in the Dongeuibogam was performed. A high-frequency medicinal herb combination group and candidates for the treatment of Parkinson-related rigidity were also selected through an analysis of medicinal herb combination frequencies. The existing literature pertaining to the potential effects of candidate herbs for Parkinson-related rigidity was reviewed. Ten medicinal herb candidates for the treatment of Parkinson-related rigidity were selected, and their respective precedent studies were analyzed.

  17. Bacterial Flagella as a Model Rigid Rod of Tunable Shape

    NASA Astrophysics Data System (ADS)

    Schwenger, Walter; Yardimci, Sevim; Gibaud, Thomas; Snow, Henry; Urbach, Jeff; Dogic, Zvonimir

    In this research, we study the physical properties of suspensions of bacterial flagella from Salmonella typhimurium prepared in a variety of rigid polymorphic shapes. Flagella act as a rigid colloidal particle that can exhibit non-trivial geometry including helices of varying dimensions, straight rods, or a combination of the two in the same filament. By controlling the conditions in which flagella are prepared, the polymorphic shape assumed by the filament can be controlled. Utilizing different polymorphic shapes, we combine results from optical microscopy observations of single filaments with bulk rheological measurements to help understand the role that constituent colloidal geometry plays in complex bulk behavior.

  18. Thermal Noise Limit in Frequency Stabilization of Lasers with Rigid Cavities

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Kemery, Amy; Camp, Jordan

    2004-01-01

    We evaluated thermal noise (Brownian motion) in a rigid reference cavity used for frequency stabilization of lasers, based on the mechanical loss of cavity materials and the numerical analysis of the mirror-spacer mechanics with t.he direct application of the fluctuation dissipation theorem. This noise sets a fundamental limit for the frequency stability achieved with a rigid frequency- reference cavity of order 1 Hz/square root Hz(0.01 Hz/square root Hz) at 10 mHz (100 Hz) at room temperature. This level coincides with the world-highest level stabilization results.

  19. A rigid disc for protection of exposed blood vessels during negative pressure wound therapy.

    PubMed

    Anesäter, Erik; Borgquist, Ola; Torbrand, Christian; Roupé, K Markus; Ingemansson, Richard; Lindstedt, Sandra; Malmsjö, Malin

    2013-02-01

    There are increasing reports of serious complications and deaths associated with negative pressure wound therapy (NPWT). Bleeding may occur when NPWT is applied to a wound with exposed blood vessels. Inserting a rigid disc in the wound may protect these structures. The authors examined the effects of rigid discs on wound bed tissue pressure and blood flow through a large blood vessel in the wound bed during NPWT. Wounds were created over the femoral artery in the groin of 8 pigs. Rigid discs were inserted. Wound bed pressures and arterial blood flow were measured during NPWT. Pressure transduction to the wound bed was similar for control wounds and wounds with discs. Blood flow through the femoral artery decreased in control wounds. When a disc was inserted, the blood flow was restored. NPWT causes hypoperfusion in the wound bed tissue, presumably as a result of mechanical deformation. The insertion of a rigid barrier alleviates this effect and restores blood flow.

  20. Effect of chain rigidity on network architecture and deformation behavior of glassy polymer networks

    NASA Astrophysics Data System (ADS)

    Knowles, Kyler Reser

    Processing carbon fiber composite laminates creates molecular-level strains in the thermoset matrix upon curing and cooling which can lead to failures such as geometry deformations, micro-cracking, and other issues. It is known strain creation is attributed to the significant volume and physical state changes undergone by the polymer matrix throughout the curing process, though storage and relaxation of cure-induced strains remain poorly understood. This dissertation establishes two approaches to address the issue. The first establishes testing methods to simultaneously measure key volumetric properties of a carbon fiber composite laminate and its polymer matrix. The second approach considers the rigidity of the polymer matrix in regards to strain storage and relaxation mechanisms which ultimately control composite performance throughout manufacturing and use. Through the use of a non-contact, full-field strain measurement technique known as digital image correlation (DIC), we describe and implement useful experiments which quantify matrix and composite parameters necessary for simulation efforts and failure models. The methods are compared to more traditional techniques and show excellent correlation. Further, we established relationships which represent matrix-fiber compatibility in regards to critical processing constraints. The second approach involves a systematic study of epoxy-amine networks which are chemically-similar but differ in chain segment rigidity. Prior research has investigated the isomer effect of glassy polymers, showing sizeable differences in thermal, volumetric, physical, and mechanical properties. This work builds on these themes and shows the apparent isomer effect is rather an effect of chain rigidity. Indeed, it was found that structurally-dissimilar polymer networks exhibit very similar properties as a consequence of their shared average network rigidity. Differences in chain packing, as a consequence of chain rigidity, were shown to

  1. Rigid Plate Fixation Versus Wire Cerclage for Sternotomy After Cardiac Surgery: A Meta-Analysis.

    PubMed

    Tam, Derrick Y; Nedadur, Rashmi; Yu, Monica; Yanagawa, Bobby; Fremes, Stephen E; Friedrich, Jan O

    2018-03-22

    Traditionally, wire cerclage has been used to reapproximate the sternum after sternotomy. Recent evidence suggests that rigid plate fixation for sternal closure may reduce the risk of sternal complications. The Medline and Embase databases were searched from inception to February 2017 for studies that compared rigid plate fixation with wire cerclage for cardiac surgery patients undergoing sternotomy. Random effects meta-analysis compared rates of sternal complications (primary outcome, defined as deep or superficial sternal wound infection, or sternal instability), early mortality, and length of stay (secondary outcomes). Three randomized controlled trials (n = 427) and five unadjusted observational studies (n = 1,025) met inclusion criteria. There was no significant difference in sternal complications with rigid plate fixation at a median of 6 months' follow-up (incidence rate ratio 0.51, 95% confidence interval [CI]: 0.20 to 1.29, p = 0.15) overall, but a decrease when including only patients at high risk for sternal complications (incidence rate ratio 0.23, 95% CI: 0.06 to 0.89, p = 0.03; two observational studies). Perioperative mortality was reduced favoring rigid plate fixation (relative risk 0.40, 95% CI: 0.28 to 0.97, p = 0.04; four observational studies and one randomized controlled trial). Length of stay was similar overall (mean difference -0.77 days, 95% CI: -1.65 to +0.12, p = 0.09), but significantly reduced with rigid plate fixation in the observational studies (mean difference -1.34 days, 95% CI: -2.05 to -0.63, p = 0.0002). This meta-analysis, driven by the results of unmatched observational studies, suggests that rigid plate fixation may lead to reduced sternal complications in patients at high risk for such events, improved perioperative survival, and decreased hospital length of stay. More randomized controlled trials are required to confirm the potential benefits of rigid plate fixation for primary sternotomy closure. Copyright

  2. Method for making one-container rigid foam

    DOEpatents

    Aubert, James H.

    2005-04-12

    A method of making a one-container foam by dissolving a polymer in liquified gas at a pressure greater than the vapor pressure of the liquified gas and than rapidly decreasing the pressure within approximately 60 seconds to foam a foam. The foam can be rigid and also have adhesive properties. The liquified gas used is CF₃ l or mixtures thereof.

  3. Synthesis of rigid polyurethane foams from phosphorylated biopolyols.

    PubMed

    de Haro, Juan Carlos; López-Pedrajas, Daniel; Pérez, Ángel; Rodríguez, Juan Francisco; Carmona, Manuel

    2017-08-18

    Renewable resources are playing a key role on the synthesis of biodegradable polyols. Moreover, the incorporation of covalently linked additives is increasing in importance in the polyurethane (PU) market. In this work, previously epoxidized grape seed oil and methyl oleate were transformed into phosphorylated biopolyols through an acid-catalyzed ring-opening hydrolysis in the presence of H 3 PO 4 . The formation of phosphate polyesters was confirmed by FT-IR and 31 P-NMR. However, the synthesis of a high-quality PU rigid foam was not possible using exclusively these polyols attending to their low hydroxyl value. In that way, different rigid PU foams were prepared from the phosphorylated biopolyols and the commercial polyol Alcupol R4520. It was observed that phosphorylated biopolyols can be incorporated up to a 57 wt.% in the PU synthesis without significant structural changes with respect to the commercial foam. Finally, thermogravimetric and EDAX analyses revealed an improvement of thermal stability by the formation of a protective phosphorocarbonaceous char layer.

  4. Conformational rigidity in a lattice model of proteins.

    PubMed

    Collet, Olivier

    2003-06-01

    It is shown in this paper that some simulations of protein folding in lattice models, which use an incorrect implementation of the Monte Carlo algorithm, do not converge towards thermal equilibrium. I developed a rigorous treatment for protein folding simulation on a lattice model relying on the introduction of a parameter standing for the rigidity of the conformations. Its properties are discussed and its role during the folding process is elucidated. The calculation of thermal properties of small chains living on a two-dimensional lattice is performed and a Bortz-Kalos-Lebowitz scheme is implemented in the presented method in order to study kinetics of chains at very low temperature. The coefficients of the Arrhenius law obtained with this algorithm are found to be in excellent agreement with the value of the main potential barrier of the system. Finally, a scenario of the mechanisms, including the rigidity parameters, that guide a protein towards its native structure, at medium temperature, is given.

  5. Lubrication of rigid ellipsida solids

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1982-01-01

    The influence of geometry on the isothermal hydrodynamic film separating two rigid solids was investigated. The minimum film thickness is derived for fully flooded conjunctions by using the Reynolds boundary conditions. It was found that the minimum film thickness had the same speed, viscosity, and load dependence as Kapitza' classical solution. However, the incorporation of Reynolds boundary conditions resulted in an additional geometry effect. Solutions using the parabolic film approximation are compared by using the exact expression for the film in the analysis. Contour plots are known that indicate in detail the pressure developed between the solids.

  6. On the aerodynamic characteristics of hovering rigid and flexible hawkmoth-like wings

    NASA Astrophysics Data System (ADS)

    Lua, K. B.; Lai, K. C.; Lim, T. T.; Yeo, K. S.

    2010-12-01

    Insect wings are subjected to fluid, inertia and gravitational forces during flapping flight. Owing to their limited rigidity, they bent under the influence of these forces. Numerical study by Hamamoto et al. (Adv Robot 21(1-2):1-21, 2007) showed that a flexible wing is able to generate almost as much lift as a rigid wing during flapping. In this paper, we take a closer look at the relationship between wing flexibility (or stiffness) and aerodynamic force generation in flapping hovering flight. The experimental study was conducted in two stages. The first stage consisted of detailed force measurement and flow visualization of a rigid hawkmoth-like wing undergoing hovering hawkmoth flapping motion and simple harmonic flapping motion, with the aim of establishing a benchmark database for the second stage, which involved hawkmoth-like wing of different flexibility performing the same flapping motions. Hawkmoth motion was conducted at Re = 7,254 and reduced frequency of 0.26, while simple harmonic flapping motion at Re = 7,800 and 11,700, and reduced frequency of 0.25. Results show that aerodynamic force generation on the rigid wing is governed primarily by the combined effect of wing acceleration and leading edge vortex generated on the upper surface of the wing, while the remnants of the wake vortices generated from the previous stroke play only a minor role. Our results from the flexible wing study, while generally supportive of the finding by Hamamoto et al. (Adv Robot 21(1-2):1-21, 2007), also reveal the existence of a critical stiffness constant, below which lift coefficient deteriorates significantly. This finding suggests that although using flexible wing in micro air vehicle application may be beneficial in term of lightweight, too much flexibility can lead to deterioration in flapping performance in terms of aerodynamic force generation. The results further show that wings with stiffness constant above the critical value can deliver mean lift coefficient

  7. Absolute rigidity spectrum of protons and helium nuclei above 10 GV/c

    NASA Technical Reports Server (NTRS)

    Golden, R. L.; Horan, S.; Kimbell, B.; Badhwar, G. D.; Lacy, J. L.; Zipse, J. E.; Daniel, R. R.; Stephens, S. A.

    1985-01-01

    Proton and helium nuclei differential spectra were gathered with a balloon borne magnet spectrometer. The data were fitted to the assumption that the differential flux can be represented by a power law in rigidity. In the rigidity range 10 to 25 GV/c the spectral indices were found to be -(2.74 plus or minus 0.04) for protons and -(2.71 plus or minus 0.05) for helium nuclei. A brief discussion is given by systematic errors.

  8. Doppler ultrasound compatible plastic material for use in rigid flow models.

    PubMed

    Wong, Emily Y; Thorne, Meghan L; Nikolov, Hristo N; Poepping, Tamie L; Holdsworth, David W

    2008-11-01

    A technique for the rapid but accurate fabrication of multiple flow phantoms with variations in vascular geometry would be desirable in the investigation of carotid atherosclerosis. This study demonstrates the feasibility and efficacy of implementing numerically controlled direct-machining of vascular geometries into Doppler ultrasound (DUS)-compatible plastic for the easy fabrication of DUS flow phantoms. Candidate plastics were tested for longitudinal speed of sound (SoS) and acoustic attenuation at the diagnostic frequency of 5 MHz. Teflon was found to have the most appropriate SoS (1376 +/- 40 m s(-1) compared with 1540 m s(-1) in soft tissue) and thus was selected to construct a carotid bifurcation flow model with moderate eccentric stenosis. The vessel geometry was machined directly into Teflon using a numerically controlled milling technique. Geometric accuracy of the phantom lumen was verified using nondestructive micro-computed tomography. Although Teflon displayed a higher attenuation coefficient than other tested materials, Doppler data acquired in the Teflon flow model indicated that sufficient signal power was delivered throughout the depth of the vessel and provided comparable velocity profiles to that obtained in the tissue-mimicking phantom. Our results indicate that Teflon provides the best combination of machinability and DUS compatibility, making it an appropriate choice for the fabrication of rigid DUS flow models using a direct-machining method.

  9. Numerical algorithm for rigid body position estimation using the quaternion approach

    NASA Astrophysics Data System (ADS)

    Zigic, Miodrag; Grahovac, Nenad

    2017-11-01

    This paper deals with rigid body attitude estimation on the basis of the data obtained from an inertial measurement unit mounted on the body. The aim of this work is to present the numerical algorithm, which can be easily applied to the wide class of problems concerning rigid body positioning, arising in aerospace and marine engineering, or in increasingly popular robotic systems and unmanned aerial vehicles. Following the considerations of kinematics of rigid bodies, the relations between accelerations of different points of the body are given. A rotation matrix is formed using the quaternion approach to avoid singularities. We present numerical procedures for determination of the absolute accelerations of the center of mass and of an arbitrary point of the body expressed in the inertial reference frame, as well as its attitude. An application of the algorithm to the example of a heavy symmetrical gyroscope is presented, where input data for the numerical procedure are obtained from the solution of differential equations of motion, instead of using sensor measurements.

  10. Effects of semi-rigid arch-support orthotics: an investigation with potential ergonomic implications.

    PubMed

    Kelaher, D; Mirka, G A; Dudziak, K Q

    2000-10-01

    For many years, arch-support orthotics have been prescribed for individuals with discomfort and/or abnormal skeletal alignments in the structures of the lower extremity. Recently there has been an increased interest in promoting semi-rigid orthotics as an ergonomic aid for asymptomatic workers who must stand all day at their workplace. A laboratory study was performed to assess the biomechanical impact of prefabricated semi-rigid orthotics on asymptomatic individuals. Ten subjects wore semi-rigid arch-support orthotics (experimental condition) for two months and flexible polyurethane/Sorbothane shoe inserts (control condition) for two months. Throughout this 18-week testing period, the subjects returned to the lab to perform a battery of assessment tests at regularly scheduled intervals. These tests examined subject strength, standing posture, stability, fatigue effects, and body part discomfort. The results of this study showed no significant changes in the strength, posture, or stability as a function of insert type. The subjects reported a reduction in low-back discomfort along with an increase in foot discomfort during a fatiguing exertion task while wearing the semi-rigid orthotics as compared to the control condition.

  11. Dynamic analysis of a system of hinge-connected rigid bodies with nonrigid appendages. [equations of motion

    NASA Technical Reports Server (NTRS)

    Likins, P. W.

    1974-01-01

    Equations of motion are derived for use in simulating a spacecraft or other complex electromechanical system amenable to idealization as a set of hinge-connected rigid bodies of tree topology, with rigid axisymmetric rotors and nonrigid appendages attached to each rigid body in the set. In conjunction with a previously published report on finite-element appendage vibration equations, this report provides a complete minimum-dimension formulation suitable for generic programming for digital computer numerical integration.

  12. The Rigid Pavement Database: Overview and Data Collection Plan

    DOT National Transportation Integrated Search

    1998-06-01

    The rigid pavement (RP) database contains historical distress data obtained from more than 400 continuously reinforced concrete pavements(CRCP) and jointed concrete pavements (JCP) across the state of Texas. Data collection efforts began in 1974 and ...

  13. Three-Axis Time-Optimal Attitude Maneuvers of a Rigid-Body

    NASA Astrophysics Data System (ADS)

    Wang, Xijing; Li, Jisheng

    With the development trends for modern satellites towards macro-scale and micro-scale, new demands are requested for its attitude adjustment. Precise pointing control and rapid maneuvering capabilities have long been part of many space missions. While the development of computer technology enables new optimal algorithms being used continuously, a powerful tool for solving problem is provided. Many papers about attitude adjustment have been published, the configurations of the spacecraft are considered rigid body with flexible parts or gyrostate-type systems. The object function always include minimum time or minimum fuel. During earlier satellite missions, the attitude acquisition was achieved by using the momentum ex change devices, performed by a sequential single-axis slewing strategy. Recently, the simultaneous three-axis minimum-time maneuver(reorientation) problems have been studied by many researchers. It is important to research the minimum-time maneuver of a rigid spacecraft within onboard power limits, because of potential space application such as surveying multiple targets in space and academic value. The minimum-time maneuver of a rigid spacecraft is a basic problem because the solutions for maneuvering flexible spacecraft are based on the solution to the rigid body slew problem. A new method for the open-loop solution for a rigid spacecraft maneuver is presented. Having neglected all perturbation torque, the necessary conditions of spacecraft from one state to another state can be determined. There is difference between single-axis with multi-axis. For single- axis analytical solution is possible and the switching line passing through the state-space origin belongs to parabolic. For multi-axis, it is impossible to get analytical solution due to the dynamic coupling between the axes and must be solved numerically. Proved by modern research, Euler axis rotations are quasi-time-optimal in general. On the basis of minimum value principles, a research for

  14. Self-sufficiency, free trade and safety.

    PubMed

    Rautonen, Jukka

    2010-01-01

    The relationship between free trade, self-sufficiency and safety of blood and blood components has been a perennial discussion topic in the blood service community. Traditionally, national self-sufficiency has been perceived as the ultimate goal that would also maximize safety. However, very few countries are, or can be, truly self-sufficient when self-sufficiency is understood correctly to encompass the whole value chain from the blood donor to the finished product. This is most striking when plasma derived medicines are considered. Free trade of blood products, or competition, as such can have a negative or positive effect on blood safety. Further, free trade of equipment and reagents and several plasma medicines is actually necessary to meet the domestic demand for blood and blood derivatives in most countries. Opposing free trade due to dogmatic reasons is not in the best interest of any country and will be especially harmful for the developing world. Competition between blood services in the USA has been present for decades. The more than threefold differences in blood product prices between European blood services indicate that competition is long overdue in Europe, too. This competition should be welcomed but carefully and proactively regulated to avoid putting safe and secure blood supply at risk. Copyright 2009 The International Association for Biologicals. Published by Elsevier Ltd. All rights reserved.

  15. Development of semi-rigid cables for low temperature superconducting detectors

    NASA Astrophysics Data System (ADS)

    Kushino, Akihiro; Kasai, Soichi

    We are developing semi-rigid cables for accurate readout of superconducting radiation/particle detectors and other low temperature experiments. The center conductor with a diameter of 0.86 mm is separated with seamless metal outer conductor by dielectric material, polytetrafluoroethylene. We used various metal materials with low thermal conductivity for the electrical conductors such as stainless-steel, cupro-nickel, brass, beryllium-copper, phosphor-bronze, niobium-titanium, and niobium. In addition to the conventional semi-rigid cables, low-pass-filter type cables were manufactured and evaluated to cut the high frequency noise into superconducting detectors. We measured their low thermal conductance and attenuation property up to 10 GHz below the liquid helium temperature.

  16. Rigid aromatic linking moiety in cationic lipids for enhanced gene transfection efficiency.

    PubMed

    Wang, Bing; Zhao, Rui-Mo; Zhang, Ji; Liu, Yan-Hong; Huang, Zheng; Yu, Qing-Ying; Yu, Xiao-Qi

    2017-08-18

    Although numerous cationic lipids have been developed as non-viral gene vectors, the structure-activity relationship (SAR) of these materials remains unclear and needs further investigation. In this work, a series of lysine-derived cationic lipids containing linkages with different rigidity were designed and synthesized. SAR studies showed that lipids with rigid aromatic linkage could promote the formation of tight liposomes and enhance DNA condensation, which is essential for the gene delivery process. These lipids could give much higher transfection efficiency than those containing more flexible aliphatic linkage in various cell lines. Moreover, the rigid aromatic linkage also affords the material higher serum tolerance ability. Flow cytometry assay revealed that the target lipids have good cellular uptake, while confocal microscopy observation showed weaker endosome escape than Lipofectamine 2000. To solve such problem and further increase the transfection efficiency, some lysosomotropic reagents were used to improve the endosome escape of lipoplex. As expected, higher transfection efficiency than Lipofectamine 2000 could be obtained via this strategy. Cytotoxicity assay showed that these lipids have lower toxicity in various cell lines than Lipofectamine 2000, suggesting their potential for further application. This work demonstrates that a rigid aromatic linkage might distinctly improve the gene transfection abilities of cationic lipids and affords information to construct safe and efficient gene vector towards practical application. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  17. Synthesis of a controller for stabilizing the motion of a rigid body about a fixed point

    NASA Astrophysics Data System (ADS)

    Zabolotnov, Yu. M.; Lobanov, A. A.

    2017-05-01

    A method for the approximate design of an optimal controller for stabilizing the motion of a rigid body about a fixed point is considered. It is assumed that rigid body motion is nearly the motion in the classical Lagrange case. The method is based on the common use of the Bellman dynamic programming principle and the averagingmethod. The latter is used to solve theHamilton-Jacobi-Bellman equation approximately, which permits synthesizing the controller. The proposed method for controller design can be used in many problems close to the problem of motion of the Lagrange top (the motion of a rigid body in the atmosphere, the motion of a rigid body fastened to a cable in deployment of the orbital cable system, etc.).

  18. Grasping rigid objects in zero-g

    NASA Astrophysics Data System (ADS)

    Anderson, Greg D.

    1993-12-01

    The extra vehicular activity helper/retriever (EVAHR) is a prototype for an autonomous free- flying robotic astronaut helper. The ability to grasp a moving object is a fundamental skill required for any autonomous free-flyer. This paper discusses an algorithm that couples resolved acceleration control with potential field based obstacle avoidance to enable a manipulator to track and capture a rigid object in (imperfect) zero-g while avoiding joint limits, singular configurations, and unintentional impacts between the manipulator and the environment.

  19. Efficacy of combining flexible and rigid ureteroscopy for transurethral lithotripsy.

    PubMed

    Shigemura, Katsumi; Yasufuku, Tomihiko; Yamashita, Masuo; Arakawa, Soichi; Fujisawa, Masato

    2010-08-23

    Transurethral lithotripsy (TUL) is a common procedure in urology. However, controversy persists about how to deal with stones pushed up into kidney from the ureter during the procedure of TUL. This study investigated the efficacy of combining flexible ureteroscopy and rigid ureteroscopy for pushed-up stones into kidney during TUL. Fotry-one patients underwent TUL by a single surgeon from July 2007 to May 2009. Eight cases resulted in pushed-up stones during operation or involved existing kidney stones. We used a Zero-tip or Litho Catch Basket catheter and a flexible ureteroscope to carry these stones in kidney down into the ureter where the rigid ureteroscope could then reach and handle the stone for lithotripsy or being taken away. A Lithoclast system was used for lithotripsy. Five cases involved stones pushed up during surgery and 3 cases involved stones already in the kidney in detail. We pulled the stones down into the ureter in all cases and successfully completed lithotripsy or removed the stone, thus avoiding the performance of additional extracorporeal shock wave lithotripsy (ESWL). In conclusions, combined use of flexible ureteroscopy and rigid ureteroscopy for upper urinary tract stones pushed up into the kidney during TUL or renal stones could be useful for avoiding additional ESWL.

  20. Non-rigid ultrasound image registration using generalized relaxation labeling process

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Ha; Seong, Yeong Kyeong; Park, MoonHo; Woo, Kyoung-Gu; Ku, Jeonghun; Park, Hee-Jun

    2013-03-01

    This research proposes a novel non-rigid registration method for ultrasound images. The most predominant anatomical features in medical images are tissue boundaries, which appear as edges. In ultrasound images, however, other features can be identified as well due to the specular reflections that appear as bright lines superimposed on the ideal edge location. In this work, an image's local phase information (via the frequency domain) is used to find the ideal edge location. The generalized relaxation labeling process is then formulated to align the feature points extracted from the ideal edge location. In this work, the original relaxation labeling method was generalized by taking n compatibility coefficient values to improve non-rigid registration performance. This contextual information combined with a relaxation labeling process is used to search for a correspondence. Then the transformation is calculated by the thin plate spline (TPS) model. These two processes are iterated until the optimal correspondence and transformation are found. We have tested our proposed method and the state-of-the-art algorithms with synthetic data and bladder ultrasound images of in vivo human subjects. Experiments show that the proposed method improves registration performance significantly, as compared to other state-of-the-art non-rigid registration algorithms.

  1. Cell movement is guided by the rigidity of the substrate

    NASA Technical Reports Server (NTRS)

    Lo, C. M.; Wang, H. B.; Dembo, M.; Wang, Y. L.

    2000-01-01

    Directional cell locomotion is critical in many physiological processes, including morphogenesis, the immune response, and wound healing. It is well known that in these processes cell movements can be guided by gradients of various chemical signals. In this study, we demonstrate that cell movement can also be guided by purely physical interactions at the cell-substrate interface. We cultured National Institutes of Health 3T3 fibroblasts on flexible polyacrylamide sheets coated with type I collagen. A transition in rigidity was introduced in the central region of the sheet by a discontinuity in the concentration of the bis-acrylamide cross-linker. Cells approaching the transition region from the soft side could easily migrate across the boundary, with a concurrent increase in spreading area and traction forces. In contrast, cells migrating from the stiff side turned around or retracted as they reached the boundary. We call this apparent preference for a stiff substrate "durotaxis." In addition to substrate rigidity, we discovered that cell movement could also be guided by manipulating the flexible substrate to produce mechanical strains in the front or rear of a polarized cell. We conclude that changes in tissue rigidity and strain could play an important controlling role in a number of normal and pathological processes involving cell locomotion.

  2. Technical characteristics of rigid sprayed PUR and PIR foams used in construction industry

    NASA Astrophysics Data System (ADS)

    Gravit, Marina; Kuleshin, Aleksey; Khametgalieva, Elina; Karakozova, Irina

    2017-10-01

    The article describes the distinctive properties of rigid polyurethane foam and polyisocyanurate (PUR and PIR). A brief review of the research was carried out on their modification with an objective to improve the thermal insulation properties and reducing the combustibility. A comparative analysis of the technical characteristics of rigid PUR and PIR foams of various manufacturers is presented. The problems of the state of the market for the production of polyurethane foam and polyisocyanurate in Russia have been marked. It is established that the further development of the fabrication technology of heat-insulating sprayed rigid PUR and PIR foams requires uniformity of technical characteristics of original components and finished products. Moreover, it requires the creation of unified information base for raw materials and auxiliary materials used in the production of PUR and PIR foam.

  3. Crack identification for rigid pavements using unmanned aerial vehicles

    NASA Astrophysics Data System (ADS)

    Bahaddin Ersoz, Ahmet; Pekcan, Onur; Teke, Turker

    2017-09-01

    Pavement condition assessment is an essential piece of modern pavement management systems as rehabilitation strategies are planned based upon its outcomes. For proper evaluation of existing pavements, they must be continuously and effectively monitored using practical means. Conventionally, truck-based pavement monitoring systems have been in-use in assessing the remaining life of in-service pavements. Although such systems produce accurate results, their use can be expensive and data processing can be time consuming, which make them infeasible considering the demand for quick pavement evaluation. To overcome such problems, Unmanned Aerial Vehicles (UAVs) can be used as an alternative as they are relatively cheaper and easier-to-use. In this study, we propose a UAV based pavement crack identification system for monitoring rigid pavements’ existing conditions. The system consists of recently introduced image processing algorithms used together with conventional machine learning techniques, both of which are used to perform detection of cracks on rigid pavements’ surface and their classification. Through image processing, the distinct features of labelled crack bodies are first obtained from the UAV based images and then used for training of a Support Vector Machine (SVM) model. The performance of the developed SVM model was assessed with a field study performed along a rigid pavement exposed to low traffic and serious temperature changes. Available cracks were classified using the UAV based system and obtained results indicate it ensures a good alternative solution for pavement monitoring applications.

  4. Swimming of an assembly of rigid spheres at low Reynolds number.

    PubMed

    Felderhof, B U

    2014-11-01

    A matrix formulation is derived for the calculation of the swimming speed and the power required for swimming of an assembly of rigid spheres immersed in a viscous fluid of infinite extent. The spheres may have arbitrary radii and may interact with elastic forces. The analysis is based on the Stokes mobility matrix of the set of spheres, defined in low Reynolds number hydrodynamics. For small amplitude, swimming optimization of the swimming speed at given power leads to an eigenvalue problem. The method allows straightforward calculation of the swimming performance of structures modeled as assemblies of interacting rigid spheres.

  5. Effectiveness of transverse grooves in rigid pavement

    NASA Astrophysics Data System (ADS)

    Gurney, G. F.; Bryden, J. E.

    1982-10-01

    Transverse grooves were installed at 11 intersection approaches on worn rigid pavement to reduce a high rate of wet road accidents. In most cases, accident reductions were experienced only at intersections with multiple negative operational characteristics, including higher approach speeds, limited sight distances, and frequent vehicle stopping for turns or stop signs. Intersections with no more than one negative characteristic generally did not benefit from grooving.

  6. Rigidity sensing explained by active matter theory.

    PubMed

    Marcq, Philippe; Yoshinaga, Natsuhiko; Prost, Jacques

    2011-09-21

    The magnitude of traction forces exerted by living animal cells on their environment is a monotonically increasing and approximately sigmoidal function of the stiffness of the external medium. We rationalize this observation using active matter theory, and propose that adaptation to substrate rigidity results from an interplay between passive elasticity and active contractility. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  7. Perioperative Brain Shift and Deep Brain Stimulating Electrode Deformation Analysis: Implications for rigid and non-rigid devices

    PubMed Central

    Sillay, Karl A.; Kumbier, L. M.; Ross, C.; Brady, M.; Alexander, A.; Gupta, A.; Adluru, N.; Miranpuri, G. S.; Williams, J. C.

    2016-01-01

    Deep brain stimulation (DBS) efficacy is related to optimal electrode placement. Several authors have quantified brain shift related to surgical targeting; yet, few reports document and discuss the effects of brain shift after insertion. Objective: To quantify brain shift and electrode displacement after device insertion. Twelve patients were retrospectively reviewed, and one post-operative MRI and one time-delayed CT were obtained for each patient and their implanted electrodes modeled in 3D. Two competing methods were employed to measure the electrode tip location and deviation from the prototypical linear implant after the resolution of acute surgical changes, such as brain shift and pneumocephalus. In the interim between surgery and a pneumocephalus free postoperative scan, electrode deviation was documented in all patients and all electrodes. Significant shift of the electrode tip was identified in rostral, anterior, and medial directions (p < 0.05). Shift was greatest in the rostral direction, measuring an average of 1.41 mm. Brain shift and subsequent electrode displacement occurs in patients after DBS surgery with the reversal of intraoperative brain shift. Rostral displacement is on the order of the height of one DBS contact. Further investigation into the time course of intraoperative brain shift and its potential effects on procedures performed with rigid and non-rigid devices in supine and semi-sitting surgical positions is needed. PMID:23010803

  8. [Quantitative measurement of axial rigidity, functional status and health-related quality of life in patients with Parkinson's disease].

    PubMed

    Cano de la Cuerda, Roberto; Vela, Lydia; Miangolarra-Page, Juan Carlos; Macías-Macías, Yolanda; Muñoz-Hellín, Elena

    2010-08-16

    Rigidity is a cardinal symptom of Parkinson's disease (PD). Clinically, rigidity is usually assessed by passively flexing and extending a patient's limb. Few studies have assessed rigidity in trunk muscles in PD patients. To develop an objective measurement to quantify trunk rigidity in PD patients, and to examine its relationship with disease severity using the Hoehn and Yahr staging score (HY) and the Unified Parkinson's Disease Rating Scale III (UPDRS-III), disease duration, functional status with the Schwab & England activities of daily living scale and health related quality of life (HRQoL) was assessed with the European Quality of Life-5 Dimensions and Parkinson's Disease Questionnaire-39 items (PDQ-39). An isokinetic dynamometer Biodex System 3 was employed to assess trunk rigidity in 36 PD patients. Passive trunk flexion and extension at 3 angular velocities, 30 degrees/s, 45 degrees/s and 60 degrees /s were applied and resistive torques were recorded as trunk flexor and extensors rigidity. Significant correlations between trunk flexors-extensors tone and HY staging score, UPDRS-III, disease duration and functional status at 30 degrees/s, 45 degrees/s and 60 degrees/s were obtained. Trunk rigidity was correlated with the HRQoL assessed with the PDQ-39. Our results suggest that the 30 degrees/s, 45 degrees/s and 60 degrees/s angular velocities of this objective method was valid to assess trunk rigidity and was correlated with disease severity, disease duration, functional status and HRQoL in PD patients.

  9. Electrical conductivity of rigid polyurethane foam at high temperature

    NASA Astrophysics Data System (ADS)

    Johnson, R. T., Jr.

    1982-08-01

    The electrical conductivity of rigid polyurethane foam, used for electronic encapsulation, was measured during thermal decomposition to 3400 C. At higher temperatures the conductance continues to increase. With pressure loaded electrical leads, sample softening results in eventual contact between electrodes which produces electrical shorting. Air and nitrogen environments show no significant dependence of the conductivity on the atmosphere over the temperature range. The insulating characteristics of polyurethane foam below approx. 2700 C are similar to those for silicone based materials used for electronic case housings and are better than those for phenolics. At higher temperatures (greater than or equal to 2700 C) the phenolics appear to be better insulators to approx. 5000 C and the silicones to approx. 6000 C. It is concluded that the Sylgard 184/GMB encapsulant is a significantly better insulator at high temperature than the rigid polyurethane foam.

  10. Dense granular flow around a rigid or flexible intruder

    NASA Astrophysics Data System (ADS)

    Kolb, Evelyne; Adda-Bedia, Mokhtar

    2012-02-01

    We experimentally studied the flow of a dense granular material around an obstacle (rigid cylinder or flexible plate) placed in a 2 dimensional confined cell at a packing fraction near the 2D jamming threshold. In the case of the rigid obstacle, the displacement field of grains as well as the drag force experienced by the obstacle were simultaneously recorded and a parametric study was done by changing the cell size, the intruder diameter or the packing fraction. The drag force experienced by the intruder and the formation of a wake behind the obstacle were very sensitive to the approach to jamming. The same experimental set-up was adapted to a flexible intruder and coupling between the granular flow and fibre deflexion were imaged. The deformation of the fibre could be compared with theoretical predictions from elastica.

  11. Working toward Self-Sufficiency.

    ERIC Educational Resources Information Center

    Caplan, Nathan

    1985-01-01

    Upon arrival in the United States, the Southeast Asian "Boat People" faced a multitude of problems that would seem to have hindered their achieving economic self-sufficiency. Nonetheless, by the time of a 1982 research study which interviewed nearly 1,400 refugee households, 25 percent of all the households in the sample had achieved…

  12. 39 CFR 491.3 - Sufficient legal form.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Sufficient legal form. 491.3 Section 491.3 Postal... AND THE POSTAL RATE COMMISSION § 491.3 Sufficient legal form. No document purporting to garnish... is legal process in the nature of garnishment; that it is issued by a court of competent jurisdiction...

  13. 39 CFR 491.3 - Sufficient legal form.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 39 Postal Service 1 2014-07-01 2014-07-01 false Sufficient legal form. 491.3 Section 491.3 Postal... AND THE POSTAL RATE COMMISSION § 491.3 Sufficient legal form. No document purporting to garnish... is legal process in the nature of garnishment; that it is issued by a court of competent jurisdiction...

  14. 27 CFR 25.174 - Bond not sufficient.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bond not sufficient. 25.174 Section 25.174 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Tax on Beer Prepayment of Tax § 25.174 Bond not sufficient. When the...

  15. 27 CFR 25.174 - Bond not sufficient.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Bond not sufficient. 25.174 Section 25.174 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL BEER Tax on Beer Prepayment of Tax § 25.174 Bond not sufficient. When the...

  16. 27 CFR 25.174 - Bond not sufficient.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Bond not sufficient. 25.174 Section 25.174 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL BEER Tax on Beer Prepayment of Tax § 25.174 Bond not sufficient. When the...

  17. 27 CFR 25.174 - Bond not sufficient.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Bond not sufficient. 25.174 Section 25.174 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Tax on Beer Prepayment of Tax § 25.174 Bond not sufficient. When the...

  18. 27 CFR 25.174 - Bond not sufficient.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Bond not sufficient. 25.174 Section 25.174 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS BEER Tax on Beer Prepayment of Tax § 25.174 Bond not sufficient. When the...

  19. When is Testing Sufficient

    NASA Technical Reports Server (NTRS)

    Rosenberg, Linda H.; Arthur, James D.; Stapko, Ruth K.; Davani, Darush

    1999-01-01

    The Software Assurance Technology Center (SATC) at NASA Goddard Space Flight Center has been investigating how projects can determine when sufficient testing has been completed. For most projects, schedules are underestimated, and the last phase of the software development, testing, must be decreased. Two questions are frequently asked: "To what extent is the software error-free? " and "How much time and effort is required to detect and remove the remaining errors? " Clearly, neither question can be answered with absolute certainty. Nonetheless, the ability to answer these questions with some acceptable level of confidence is highly desirable. First, knowing the extent to which a product is error-free, we can judge when it is time to terminate testing. Secondly, if errors are judged to be present, we can perform a cost/benefit trade-off analysis to estimate when the software will be ready for use and at what cost. This paper explains the efforts of the SATC to help projects determine what is sufficient testing and when is the most cost-effective time to stop testing.

  20. Unevenness of Sliding Surface of Overhead Rigid Conductor Lines and Method for Reducing Unevenness

    NASA Astrophysics Data System (ADS)

    Aboshi, Mitsuo; Shimizu, Masashi

    Rigid conductor lines are used in many subways, because the use of such conductor lines reduces the risk of accidents and because less space is required for their installation. However, as the unevenness of the sliding surface of the rigid conductor lines significantly influences the fluctuations in the contact force between pantographs and contact lines, it is necessary to decrease the unevenness at the construction as well as the maintenance stages. In order to investigate the installation accuracy of overhead rigid conductor lines, we have developed a device that accurately and continuously measures the unevenness of the sliding surface. By using this measuring device, we have confirmed that the unevenness of the sliding surface depends on various factors such as the sag between the support points, the deformation of the aluminum base or the conductive rail in the case of a long wavelength, the slight sagging unevenness between the bolts of the long ear, the undulating wear etc. This paper describes the actual unevenness conditions and the technical methods for decreasing the unevenness of the sliding surface of overhead rigid conductor lines.

  1. Communication: Rotational excitation of HCl by H: Rigid rotor vs. reactive approaches

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

    Lique, François, E-mail: francois.lique@univ-lehavre.fr

    2015-06-28

    We report fully quantum time-independent calculations of cross sections for the collisional excitation of HCl by H, an astrophysically relevant process. Our calculations are based on the Bian-Werner ClH{sub 2} potential energy surface and include the possibility of HCl destruction through reactive collisions. The strongest collision-induced rotational HCl transitions are those with Δj = 1, and the magnitude of the HCl-H inelastic cross sections is of the same order of magnitude as the HCl-H{sub 2} ones. Results of exact calculations, i.e., including the reactive channels, are compared to pure inelastic calculations based on the rigid rotor approximation. A very goodmore » agreement is found between the two approaches over the whole energy range 10–3000 cm{sup −1}. At the highest collisional energies, where the reaction takes place, the rigid rotor approach slightly overestimates the cross sections, as expected. Hence, the rigid rotor approach is found to be reliable at interstellar temperatures.« less

  2. Vertical bending strength and torsional rigidity analysis of formula student car chassis

    NASA Astrophysics Data System (ADS)

    Hazimi, Hashfi; Ubaidillah, Setiyawan, Adi Eka Putra; Ramdhani, Hanief Cahya; Saputra, Murnanda Zaesy; Imaduddin, Fitrian

    2018-02-01

    Formula Society of Automotive Engineers (FSAE) is a competition for students to construct formula student car. One of an essential part of a formula student car is its chassis. Chassis is an internal vehicle frame which holds all another part of the vehicle and secures the driver. The team have to design their chassis and tests their design to achieve the best chassis that fulfill the regulation. This paper contains chassis design from Bengawan FSAE Team and some FEA tests to find out the Tensile Strength, Torsional Rigidity, and Von Misses Stress of Formula SAE car. Torsional rigidity was found by applying the static torsional test. The results from torsional rigidity test are a maximum deformation of 9.9512 mm with 1.7064 safety factor, and 35.935 MPa maximum Von Misses Stress. Moreover, then the result of the vertical bending strength test is 8.1214 mm max deformation with safety factor 4.2717, and 29.226 MPa maximum Von Misses Stress.

  3. Rigid High Temperature Heat-Shrinkable Polyimide Tubes with Functionality as Reducer Couplings

    PubMed Central

    Kong, Deyan; Xiao, Xinli

    2017-01-01

    Flexible and semi-rigid heat-shrinkable tubes (HSTs) have been used in thousands of applications, and here rigid high temperature HSTs are reported for the first time. These rigid HSTs are prepared with shape memory polyimides possessing glass transition temperatures (Tgs) from 182 to 295 °C, and the relationships between Tg and their molecular structures are studied. The polyimide HSTs (PIHSTs) can fix expanded diameters and shrink back to original diameters very well, and the mechanisms of their heat-shrinkage performance are discussed. Their differences from commercially available HSTs in heat-shrinkage are also analyzed. They can withstand low temperature of −196 °C, much lower than those of other HSTs. The PIHSTs can also connect subjects of different sizes by heat-shrinkage and then fix them upon cooling like reducer couplings, and the possible mechanisms of their reducer coupling effect are analyzed. With their unique characteristics, PIHSTs will expand the application areas of HSTs enormously. PMID:28317905

  4. Soft cast versus rigid cast for treatment of distal radius buckle fractures in children.

    PubMed

    Witney-Lagen, Caroline; Smith, Christine; Walsh, Graham

    2013-04-01

    Buckle fractures are extremely common and their optimum management is still under debate. This study aimed to ascertain whether buckle fractures of the distal radius can be safely and effectively treated in soft cast with only a single orthopaedic outpatient clinic appointment. A total of 232 children with buckle fractures of the distal radius were included in the study. 111 children with 112 distal radius fractures were treated in full rigid cast and 121 children with 123 fractures were treated with soft cast. The rigid cast children attended outpatient clinic for removal of cast at 3 weeks. Soft casts were removed by parents unwinding the cast at home after 3 weeks. Follow-up was conducted prospectively by telephone questionnaire at an average of 6 weeks post-injury. Outcome data were available for 117 children treated in soft cast and for 102 children treated in rigid cast. The most common mechanism of injury was a fall sustained from standing or running, followed by falls from bikes and then trampoline accidents. Overall, both groups recovered well. Overall satisfaction with the outcome of treatment was 97.4% in soft cast and 95.2% in rigid cast. Casts were reported as comfortable by 95.7% in soft cast and 93.3% in rigid cast. Cast changes were required for 6.8% of soft casts and 11.5% of rigid casts. The most frequent cause for changing rigid casts was getting the cast wet. None of the improved scores seen in the soft cast group were statistically significant. No re-fractures were seen in either group. Nearly all (94.9%) children in soft cast did bathe, shower or swim in their cast. Parents of both groups preferred treatment with soft cast (p < 0.001). Reasons given for preferring the soft cast included the ability to get the cast wet, avoidance of the plaster saw and not having to take time off work to attend a follow-up visit for cast removal. Buckle fractures of the distal radius can be safely and effectively treated in soft cast with only a single

  5. Analyses performed using the rigid pavement database in Texas.

    DOT National Transportation Integrated Search

    2004-04-01

    This report is the fifth out of six reports prepared for Research Project 0-1778 TxDOT Rigid Pavement : Database, conducted by the Center for Transportation Research (CTR) of the University of Texas at Austin : and funded by the Texas Departmen...

  6. Initial experience using the rigid forceps technique to remove wall-embedded IVC filters.

    PubMed

    Avery, Allan; Stephens, Maximilian; Redmond, Kendal; Harper, John

    2015-06-01

    Severely tilted and embedded inferior vena cava (IVC) filters remain the most challenging IVC filters to remove. Heavy endothelialisation over the filter hook can prevent engagement with standard snare and cone recovery techniques. The rigid forceps technique offers a way to dissect the endothelial cap and reliably retrieve severely tilted and embedded filters. By developing this technique, failed IVC retrieval rates can be significantly reduced and the optimum safety profile offered by temporary filters can be achieved. We present our initial experience with the rigid forceps technique described by Stavropoulos et al. for removing wall-embedded IVC filters. We retrospectively reviewed the medical imaging and patient records of all patients who underwent a rigid forceps filter removal over a 22-month period across two tertiary referral institutions. The rigid forceps technique had a success rate of 85% (11/13) for IVC filter removals. All filters in the series showed evidence of filter tilt and embedding of the filter hook into the IVC wall. Average filter tilt from the Z-axis was 19 degrees (range 8-56). Filters observed in the case study were either Bard G2X (n = 6) or Cook Celect (n = 7). Average filter dwell time was 421 days (range 47-1053). There were no major complications observed. The rigid forceps technique can be readily emulated and is a safe and effective technique to remove severely tilted and embedded IVC filters. The development of this technique across both institutions has increased the successful filter removal rate, with perceived benefits to the safety profile of our IVC filter programme. © 2015 The Royal Australian and New Zealand College of Radiologists.

  7. Can deformation of a polymer film with a rigid coating model geophysical processes?

    NASA Astrophysics Data System (ADS)

    Volynskii, A. L.; Bazhenov, S. L.

    2007-12-01

    The structural and mechanical behavior of polymer films with a thin rigid coating is analyzed. The behavior of such systems under applied stress is accompanied by the formation of a regular wavy surface relief and by regular fragmentation of the coating. The above phenomena are shown to be universal. Both phenomena (stress-induced development of a regular wavy surface relief and regular fragmentation of the coating) are provided by the specific features of mechanical stress transfer from a compliant soft support to a rigid thin coating. The above phenomena are associated with a specific structure of the system, which is referred to as “a rigid coating on a soft substratum” system (RCSS). Surface microrelief in RCSS systems is similar to the ocean floor relief in the vicinity of mid-oceanic ridges. Thus, the complex system composed of a young oceanic crust and upper Earth's mantle may be considered as typically “a solid coating on a soft substratum” system. Specific features of the ocean floor relief are analyzed in terms of the approach advanced for the description of the structural mechanical behavior of polymer films with a rigid coating. This analysis allowed to estimate the strength of an ocean floor.

  8. Neural targets for relieving parkinsonian rigidity and bradykinesia with pallidal deep brain stimulation

    PubMed Central

    Zhang, Jianyu; Ghosh, Debabrata; McIntyre, Cameron C.; Vitek, Jerrold L.

    2012-01-01

    Clinical evidence has suggested that subtle changes in deep brain stimulation (DBS) settings can have differential effects on bradykinesia and rigidity in patients with Parkinson's disease. In this study, we first investigated the degree of improvement in bradykinesia and rigidity during targeted globus pallidus DBS in three 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated rhesus macaques. Behavioral outcomes of DBS were then coupled with detailed, subject-specific computational models of neurons in the globus pallidus internus (GPi), globus pallidus externus (GPe), and internal capsule (IC) to determine which neuronal pathways when modulated with high-frequency electrical stimulation best correlate with improvement in motor symptoms. The modeling results support the hypothesis that multiple neuronal pathways can underlie the therapeutic effect of DBS on parkinsonian bradykinesia and rigidity. Across all three subjects, improvements in rigidity correlated most strongly with spread of neuronal activation into IC, driving a small percentage of fibers within this tract (<10% on average). The most robust effect on bradykinesia resulted from stimulating a combination of sensorimotor axonal projections within the GP, specifically at the site of the medial medullary lamina. Thus the beneficial effects of pallidal DBS for parkinsonian symptoms may occur from multiple targets within and near the target nucleus. PMID:22514292

  9. The Role of Rigidity in Adaptive and Maladaptive Families Assessed by FACES IV: The Points of View of Adolescents.

    PubMed

    Everri, Marina; Mancini, Tiziana; Fruggeri, Laura

    Previous studies using Olson's Circumplex Model and FACES IV, the self-report assessing family functioning, did not clarify the role of rigidity, a dimension of this model. Rigidity emerged as ambiguous: it was considered either as a functional or as a dysfunctional dimension. Building upon the results of previous studies, we provided a contribution intended to disambiguate the role of rigidity considering adolescents' perceptions and using a non-a priori classification analysis. 320 Italian adolescents (13-21 years) participated in this study and responded to a questionnaire containing scales of the study variables. A latent class analysis was performed to identify the association of rigidity with the other dimensions of Olson's model and with indicators of adaptive family functioning in adolescence: parental monitoring and family satisfaction. We found six clusters corresponding to family typologies and having different levels of functioning. Rigidity emerged as adaptive in the typologies named rigidly balanced and flexibly oscillating; it was associated with positive dimensions of family functioning, i.e. flexibility, cohesion, parental monitoring, and high levels of family satisfaction. Differently, when rigidity was associated with disengagement, low cohesion and flexibility, and lack of parental supervision, emerged as maladaptive. This was the case of two typologies: the rigidly disengaged and the chaotically disengaged. Adolescents of these families reported the lowest levels of satisfaction. In the two last typologies, the flexibly chaotic and the cohesively disorganized, rigidity indicated a mid-range functionality as these families were characterized by emotional connectedness but lack of containment. Clinical implications are discussed.

  10. Tidal Evolution of Asteroidal Binaries. Ruled by Viscosity. Ignorant of Rigidity.

    NASA Astrophysics Data System (ADS)

    Efroimsky, Michael

    2015-10-01

    This is a pilot paper serving as a launching pad for study of orbital and spin evolution of binary asteroids. The rate of tidal evolution of asteroidal binaries is defined by the dynamical Love numbers kl divided by quality factors Q. Common in the literature is the (oftentimes illegitimate) approximation of the dynamical Love numbers with their static counterparts. Since the static Love numbers are, approximately, proportional to the inverse rigidity, this renders a popular fallacy that the tidal evolution rate is determined by the product of the rigidity by the quality factor: {k}l/Q\\propto 1/(μ Q). In reality, the dynamical Love numbers depend on the tidal frequency and all rheological parameters of the tidally perturbed body (not just rigidity). We demonstrate that in asteroidal binaries the rigidity of their components plays virtually no role in tidal friction and tidal lagging, and thereby has almost no influence on the intensity of tidal interactions (tidal torques, tidal dissipation, tidally induced changes of the orbit). A key quantity that overwhelmingly determines the tidal evolution is a product of the effective viscosity η by the tidal frequency χ . The functional form of the torque’s dependence on this product depends on who wins in the competition between viscosity and self-gravitation. Hence a quantitative criterion, to distinguish between two regimes. For higher values of η χ , we get {k}l/Q\\propto 1/(η χ ), {while} for lower values we obtain {k}l/Q\\propto η χ . Our study rests on an assumption that asteroids can be treated as Maxwell bodies. Applicable to rigid rocks at low frequencies, this approximation is used here also for rubble piles, due to the lack of a better model. In the future, as we learn more about mechanics of granular mixtures in a weak gravity field, we may have to amend the tidal theory with other rheological parameters, ones that do not show up in the description of viscoelastic bodies. This line of study provides

  11. Biomechanical Effects of a Dynamic Topping off Instrumentation in a Long Rigid Pedicle Screw Construct.

    PubMed

    Reichl, Michael; Kueny, Rebecca A; Danyali, Reza; Obid, Peter; Übeyli, Hüseyin; Püschel, Klaus; Morlock, Michael M; Huber, Gerd; Niemeyer, Thomas; Richter, Alexander

    2017-05-01

    Biomechanical ex vivo study. To determine if topping off instrumentation can reduce the hypermobility in the adjacent segments when compared with the classic rigid spinal instrumentation. Long rigid instrumentation might increase the mechanical load in the adjacent segments, the resulting hypermobility, and the risk for adjacent segment disease. Topping off instrumentation intends to reduce the hypermobility at the adjacent level by more evenly distributing segmental motion and, thereby, potentially mitigating adjacent level disease. Eight human spines (Th12-L5) were divided into 2 groups. In the rigid group, a 3-segment metal rod instrumentation (L2-L5) was performed. The hybrid group included a 2-segment metal rod instrumentation (L3-L5) with a dynamic topping off instrumentation (L2-L3). Each specimen was tested consecutively in 3 different configurations: native (N=8), 2-segment rod instrumentation (L3-L5, N=8), 3-segment instrumentation (rigid: N=4, hybrid: N=4). For each configuration the range of motion (ROM) of the whole spine and each level was measured by a motion capture system during 5 cycles of extension-flexion (angle controlled to ±5 degrees, 0.1 Hz frequency, no preload). In comparison with the intact spine, both the rigid 3-segment instrumentation and the hybrid instrumentation significantly reduced the ROM in the instrumented segments (L2-L5) while increasing the movement in the adjacent segment L1-L2 (P=0.002, η=0.82) and in Th12-L1 (P<0.001, η=0.90). There were no ROM differences between the rigid and hybrid instrumentation in all segments. Introducing the dynamic topping off did not impart any significant difference in the segmental motion when compared with the rigid instrumentation. Therefore, the current biomechanical study could not show a benefit of using this specific topping off instrumentation to solve the problem of adjacent segment disease.

  12. Rigidity-patterned polyelectrolyte films to control myoblast cell adhesion and spatial organization

    PubMed Central

    Monge, Claire; Saha, Naresh; Boudou, Thomas; Pózos-Vásquez, Cuauhtemoc; Dulong, Virginie; Glinel, Karine; Picart, Catherine

    2014-01-01

    In vivo, cells are sensitive to the stiffness of their micro-environment and especially to the spatial organization of the stiffness. In vitro studies of this phenomenon can help to better understand the mechanisms of the cell response to spatial variations of the matrix stiffness. In this work, we design polelyelectrolyte multilayer films made of poly(L-lysine) and a photo-reactive hyaluronan derivative. These films can be photo-crosslinked through a photomask to create spatial patterns of rigidity. Quartz substrates incorporating a chromium mask are prepared to expose selectively the film to UV light (in a physiological buffer), without any direct contact between the photomask and the soft film. We show that these micropatterns are chemically homogeneous and flat, without any preferential adsorption of adhesive proteins. Three groups of pattern geometries differing by their shape (circles or lines), size (form 2 to 100 μm) or interspacing distance between the motifs are used to study the adhesion and spatial organization of myoblast cells. On large circular micropatterns, the cells form large assemblies that are confined to the stiffest parts. Conversely, when the size of the rigidity patterns is subcellular, the cells respond by forming protrusions. Finally, on linear micropatterns of rigidity, myoblasts align and their nuclei drastically elongate in specific conditions. These results pave the way for the study of the different steps of myoblast fusion in response to matrix rigidity in well-defined geometrical conditions. PMID:25100929

  13. Attitude output feedback control for rigid spacecraft with finite-time convergence.

    PubMed

    Hu, Qinglei; Niu, Guanglin

    2017-09-01

    The main problem addressed is the quaternion-based attitude stabilization control of rigid spacecraft without angular velocity measurements in the presence of external disturbances and reaction wheel friction as well. As a stepping stone, an angular velocity observer is proposed for the attitude control of a rigid body in the absence of angular velocity measurements. The observer design ensures finite-time convergence of angular velocity state estimation errors irrespective of the control torque or the initial attitude state of the spacecraft. Then, a novel finite-time control law is employed as the controller in which the estimate of the angular velocity is used directly. It is then shown that the observer and the controlled system form a cascaded structure, which allows the application of the finite-time stability theory of cascaded systems to prove the finite-time stability of the closed-loop system. A rigorous analysis of the proposed formulation is provided and numerical simulation studies are presented to help illustrate the effectiveness of the angular-velocity observer for rigid spacecraft attitude control. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  14. Large-Eddy-Simulation of a flow over a submerged rigid canopy

    NASA Astrophysics Data System (ADS)

    Monti, Alessandro; Omidyeganeh, Mohammad; Pinelli, Alfredo

    2017-11-01

    We have performed a wall-resolved Large-Eddy-Simulation of flow over a shallow submerged rigid canopy (H / h = 4 ; H and h are the open channel and the canopy heights respectively) in a transitional/dense regime (Nepf ARFM 44, 2011), at low Reynolds number (Reb =Ubulk H / ν = 6000). An immersed boundary method (Favier et al. JCP 261, 2013) has been adopted to represent filamentous rigid elements of the canopy. The presence of the permeable and porous canopy induces a typical inflection point in the mean velocity profile, depicting two separated and developed layers, outer boundary layer and in-canopy uniform flow. The aim of the work is to explore and unravel the mechanisms of the interaction between the fluid flow and the rigid canopy by identifying the physical parameters that govern the mixing mechanisms within the different flow layers and by exploring the impact of the sweep/ejection events at the canopy edge. The results show that the flow is characterised by large scale stream- and span-wise vortices and regions of different dynamics that affect also the filamentous layer, hence the mixing mechanisms.

  15. Apparent negative mass in QCM sensors due to punctual rigid loading

    NASA Astrophysics Data System (ADS)

    Castro, P.; Resa, P.; Elvira, L.

    2012-12-01

    Quartz Crystal Microbalances (QCM) are highly sensitive piezoelectric sensors able to detect very small loads attached to them. These devices are widely employed in many applications including process control and industrial and environmental monitoring. Mass loading is usually related to frequency shift by the well-known Sauerbrey's equation, valid for thin rigid homogeneous films. However, a significant deviation from this equation can occur when the mass is not uniformly distributed over the surface. Whereas the effects of a thin film on a QCM have been thoroughly studied, there are relatively few results on punctual loads, even though particles are usually deposited randomly and non-uniformly on the resonator surface. In this work, we have studied the effect of punctual rigid loading on the resonant frequency shift of a QCM sensor, both experimentally and using finite element method (FEM). The FEM numerical analysis was done using COMSOL software, 3D modeling a linear elastic piezoelectric solid and introducing the properties of an AT-cut quartz crystal. It is shown that a punctual rigid mass deposition on the surface of a QCM sensor can lead to positive shifts of resonance frequency, contrary to Sauerbrey's equation.

  16. Multifocal rigid gas permeable contact lenses with reduced halo

    NASA Astrophysics Data System (ADS)

    ben Yaish, Shai; Zlotnik, Alex; Limon, Ofer; Lahav Yacouel, Karen; Doron, Ravid; Zalevsky, Zeev

    2014-05-01

    In this communication we present the first dispensing medical trial in which we successfully report on testing of novel extended depth of focus rigid gas permeable (RGP) contact lenses having reduced halo and distinct focal peaks for near and far distance vision.

  17. High precision NC lathe feeding system rigid-flexible coupling model reduction technology

    NASA Astrophysics Data System (ADS)

    Xuan, He; Hua, Qingsong; Cheng, Lianjun; Zhang, Hongxin; Zhao, Qinghai; Mao, Xinkai

    2017-08-01

    This paper proposes the use of dynamic substructure method of reduction of order to achieve effective reduction of feed system for high precision NC lathe feeding system rigid-flexible coupling model, namely the use of ADAMS to establish the rigid flexible coupling simulation model of high precision NC lathe, and then the vibration simulation of the period by using the FD 3D damper is very effective for feed system of bolt connection reduction of multi degree of freedom model. The vibration simulation calculation is more accurate, more quickly.

  18. The Effect of Soft and Rigid Cervical Collars on Head and Neck Immobilization in Healthy Subjects.

    PubMed

    Barati, Kourosh; Arazpour, Mokhtar; Vameghi, Roshanak; Abdoli, Ali; Farmani, Farzad

    2017-06-01

    Whiplash injury is a prevalent and often destructive injury of the cervical column, which can lead to serious neck pain. Many approaches have been suggested for the treatment of whiplash injury, including anti-inflammatory drugs, manipulation, supervised exercise, and cervical collars. Cervical collars are generally divided into two groups: soft and rigid collars. The present study aimed to compare the effect of soft and rigid cervical collars on immobilizing head and neck motion. Many studies have investigated the effect of collars on neck motion. Rigid collars have been shown to provide more immobilization in the sagittal and transverse planes compared with soft collars. However, according to some studies, soft and rigid collars provide the same range of motion in the frontal plane. Twenty-nine healthy subjects aged 18-26 participated in this study. Data were collected using a three-dimensional motion analysis system and six infrared cameras. Eight markers, weighing 4.4 g and thickened 2 cm 2 were used to record kinematic data. According to the normality of the data, a paired t -test was used for statistical analyses. The level of significance was set at α=0.01. All motion significantly decreased when subjects used soft collars ( p <0.01). According to the obtained data, flexion and lateral rotation experienced the maximum (39%) and minimum (11%) immobilization in all six motions using soft collars. Rigid collars caused maximum immobilization in flexion (59%) and minimum immobilization in the lateral rotation (18%) and limited all motion much more than the soft collar. This study showed that different cervical collars have different effects on neck motion. Rigid and soft cervical collars used in the present study limited the neck motion in both directions. Rigid collars contributed to significantly more immobilization in all directions.

  19. Misperceptions of angular velocities influence the perception of rigidity in the kinetic depth effect

    NASA Technical Reports Server (NTRS)

    Domini, F.; Caudek, C.; Proffitt, D. R.; Kaiser, M. K. (Principal Investigator)

    1997-01-01

    Accuracy in discriminating rigid from nonrigid motion was investigated for orthographic projections of three-dimension rotating objects. In 3 experiments the hypothesis that magnitudes of angular velocity are misperceived in the kinetic depth effect was tested, and in 4 other experiments the hypothesis that misperceiving angular velocities leads to misperceiving rigidity was tested. The principal findings were (a) the magnitude of perceived angular velocity is derived heuristically as a function of a property of the first-order optic flow called deformation and (b) perceptual performance in discriminating rigid from nonrigid motion is accurate in cases when the variability of the deformations of the individual triplets of points of the stimulus displays favors this interpretation and not accurate in other cases.

  20. Misperceptions of angular velocities influence the perception of rigidity in the kinetic depth effect.

    PubMed

    Domini, F; Caudek, C; Proffitt, D R

    1997-08-01

    Accuracy in discriminating rigid from nonrigid motion was investigated for orthographic projections of three-dimension rotating objects. In 3 experiments the hypothesis that magnitudes of angular velocity are misperceived in the kinetic depth effect was tested, and in 4 other experiments the hypothesis that misperceiving angular velocities leads to misperceiving rigidity was tested. The principal findings were (a) the magnitude of perceived angular velocity is derived heuristically as a function of a property of the first-order optic flow called deformation and (b) perceptual performance in discriminating rigid from nonrigid motion is accurate in cases when the variability of the deformations of the individual triplets of points of the stimulus displays favors this interpretation and not accurate in other cases.

  1. New Langevin and gradient thermostats for rigid body dynamics.

    PubMed

    Davidchack, R L; Ouldridge, T E; Tretyakov, M V

    2015-04-14

    We introduce two new thermostats, one of Langevin type and one of gradient (Brownian) type, for rigid body dynamics. We formulate rotation using the quaternion representation of angular coordinates; both thermostats preserve the unit length of quaternions. The Langevin thermostat also ensures that the conjugate angular momenta stay within the tangent space of the quaternion coordinates, as required by the Hamiltonian dynamics of rigid bodies. We have constructed three geometric numerical integrators for the Langevin thermostat and one for the gradient thermostat. The numerical integrators reflect key properties of the thermostats themselves. Namely, they all preserve the unit length of quaternions, automatically, without the need of a projection onto the unit sphere. The Langevin integrators also ensure that the angular momenta remain within the tangent space of the quaternion coordinates. The Langevin integrators are quasi-symplectic and of weak order two. The numerical method for the gradient thermostat is of weak order one. Its construction exploits ideas of Lie-group type integrators for differential equations on manifolds. We numerically compare the discretization errors of the Langevin integrators, as well as the efficiency of the gradient integrator compared to the Langevin ones when used in the simulation of rigid TIP4P water model with smoothly truncated electrostatic interactions. We observe that the gradient integrator is computationally less efficient than the Langevin integrators. We also compare the relative accuracy of the Langevin integrators in evaluating various static quantities and give recommendations as to the choice of an appropriate integrator.

  2. Cohomological rigidity of manifolds defined by 3-dimensional polytopes

    NASA Astrophysics Data System (ADS)

    Buchstaber, V. M.; Erokhovets, N. Yu.; Masuda, M.; Panov, T. E.; Park, S.

    2017-04-01

    A family of closed manifolds is said to be cohomologically rigid if a cohomology ring isomorphism implies a diffeomorphism for any two manifolds in the family. Cohomological rigidity is established here for large families of 3-dimensional and 6-dimensional manifolds defined by 3-dimensional polytopes. The class \\mathscr{P} of 3-dimensional combinatorial simple polytopes P different from tetrahedra and without facets forming 3- and 4-belts is studied. This class includes mathematical fullerenes, that is, simple 3- polytopes with only 5-gonal and 6-gonal facets. By a theorem of Pogorelov, any polytope in \\mathscr{P} admits in Lobachevsky 3-space a right-angled realisation which is unique up to isometry. Our families of smooth manifolds are associated with polytopes in the class \\mathscr{P}. The first family consists of 3-dimensional small covers of polytopes in \\mathscr{P}, or equivalently, hyperbolic 3-manifolds of Löbell type. The second family consists of 6-dimensional quasitoric manifolds over polytopes in \\mathscr{P}. Our main result is that both families are cohomologically rigid, that is, two manifolds M and M' from either family are diffeomorphic if and only if their cohomology rings are isomorphic. It is also proved that if M and M' are diffeomorphic, then their corresponding polytopes P and P' are combinatorially equivalent. These results are intertwined with classical subjects in geometry and topology such as the combinatorics of 3-polytopes, the Four Colour Theorem, aspherical manifolds, a diffeomorphism classification of 6-manifolds, and invariance of Pontryagin classes. The proofs use techniques of toric topology. Bibliography: 69 titles.

  3. Applications of rigid and flexible GRIN-endoscopes

    NASA Astrophysics Data System (ADS)

    Schenkl, Selma; Ehlers, Alexander; Riemann, Iris; Messerschmidt, Bernhard; Bückle, Rainer; König, Karsten

    2007-02-01

    Multiphoton autofluorescence imaging became an important technique for minimal invasive examination of cells in biological tissue. Rigid and flexible endoscopes based on gradient index lenses (GRIN-lenses) extend this minimalinvasive technique to deep lying cell layers, inner body and specimens, difficult to access. In the rigid endoscope, a GRIN-lens overcomes the limited depth range, given by the working distance of the microscope objective. The focus of the conventional laser scanning tomography is reproduced tens of millimeters in the specimen under study by the GRIN-lens (diameter 1.8 and 3 μm). We will present images of fluorescent beads, proteins cells and skin tissue, as well as first in vivo measurements on human skin. The autofluorescence signal stems from the endogenous fluorophore elastin and SHG from collagen. The flexible endoscope dispenses completely the need of a microscope next to the specimen of interest. The excitation laser pulses is delivered via a well-characterized photonic crystal fiber and subsequently focused by a newly designed GRIN-lens system. The fluorescence, also transferred by a fiber is detected by a PMT detector. We will show the excellent imaging qualities of a newly developed GRIN-lens system with high-resolution images of proteins, cells and plant tissue and give an out-look on multiphoton endoscopy.

  4. Glycerol in micellar confinement with tunable rigidity

    NASA Astrophysics Data System (ADS)

    Lannert, Michael; Müller, Allyn; Gouirand, Emmanuel; Talluto, Vincenzo; Rosenstihl, Markus; Walther, Thomas; Stühn, Bernd; Blochowicz, Thomas; Vogel, Michael

    2016-12-01

    We investigate the glassy dynamics of glycerol in the confinement of a microemulsion system, which is stable on cooling down to the glass transition of its components. By changing the composition, we vary the viscosity of the matrix, while keeping the confining geometry intact, as is demonstrated by small angle X-ray scattering. By means of 2H NMR, differential scanning calorimetry, and triplet solvation dynamics we, thus, probe the dynamics of glycerol in confinements of varying rigidity. 2H NMR results show that, at higher temperatures, the dynamics of confined glycerol is unchanged compared to bulk behavior, while the reorientation of glycerol molecules becomes significantly faster than in the bulk in the deeply supercooled regime. However, comparison of different 2H NMR findings with data from calorimetry and solvation dynamics reveals that this acceleration is not due to the changed structural relaxation of glycerol, but rather due to the rotational motion of essentially rigid glycerol droplets or of aggregates of such droplets in a more fluid matrix. Thus, independent of the matrix mobility, the glycerol dynamics remains unchanged except for the smallest droplets, where an increase of Tg and, thus, a slowdown of the structural relaxation is observed even in a fluid matrix.

  5. Rigidity in vacuum under conformal symmetry

    NASA Astrophysics Data System (ADS)

    Galloway, Gregory J.; Vega, Carlos

    2018-04-01

    Motivated in part by Eardley et al. (Commun Math Phys 106(1):137-158, 1986), in this note we obtain a rigidity result for globally hyperbolic vacuum spacetimes in arbitrary dimension that admit a timelike conformal Killing vector field. Specifically, we show that if M is a Ricci flat, timelike geodesically complete spacetime with compact Cauchy surfaces that admits a timelike conformal Killing field X, then M must split as a metric product, and X must be Killing. This gives a partial proof of the Bartnik splitting conjecture in the vacuum setting.

  6. A boundary integral approach to the scattering of nonplanar acoustic waves by rigid bodies

    NASA Technical Reports Server (NTRS)

    Gallman, Judith M.; Myers, M. K.; Farassat, F.

    1990-01-01

    The acoustic scattering of an incident wave by a rigid body can be described by a singular Fredholm integral equation of the second kind. This equation is derived by solving the wave equation using generalized function theory, Green's function for the wave equation in unbounded space, and the acoustic boundary condition for a perfectly rigid body. This paper will discuss the derivation of the wave equation, its reformulation as a boundary integral equation, and the solution of the integral equation by the Galerkin method. The accuracy of the Galerkin method can be assessed by applying the technique outlined in the paper to reproduce the known pressure fields that are due to various point sources. From the analysis of these simpler cases, the accuracy of the Galerkin solution can be inferred for the scattered pressure field caused by the incidence of a dipole field on a rigid sphere. The solution by the Galerkin technique can then be applied to such problems as a dipole model of a propeller whose pressure field is incident on a rigid cylinder. This is the groundwork for modeling the scattering of rotating blade noise by airplane fuselages.

  7. Stiffness-generated rigid-body mode shapes for Lanczos eigensolution with SUPORT DOF by way of a MSC/NASTRAN DMAP alter

    NASA Technical Reports Server (NTRS)

    Abdallah, Ayman A.; Barnett, Alan R.; Widrick, Timothy W.; Manella, Richard T.; Miller, Robert P.

    1994-01-01

    When using all MSC/NASTRAN eigensolution methods except Lanczos, the analyst can replace the coupled system rigid-body modes calculated within DMAP module READ with mass orthogonalized and normalized rigid-body modes generated from the system stiffness. This option is invoked by defining MSC/NASTRAN r-set degrees of freedom via the SUPORT bulk data card. The newly calculated modes are required if the rigid-body modes calculated by the eigensolver are not 'clean' due to numerical roundoffs in the solution. When performing transient structural dynamic load analysis, the numerical roundoffs can result in inaccurate rigid-body accelerations which affect steady-state responses. Unfortunately, when using the Lanczos method and defining r-set degrees of freedom, the rigid-body modes calculated within DMAP module REIGL are retained. To overcome this limitation and to allow MSC/NASTRAN to handle SUPORT degrees of freedom identically for all eigensolvers, a DMAP Alter has been written which replaces Lanczos-calculated rigid-body modes with stiffness-generated rigid-body modes. The newly generated rigid-body modes are normalized with respect to the system mass and orthogonalized using the Gram-Schmidt technique. This algorithm has been implemented as an enhancement to an existing coupled loads methodology.

  8. [Doppler ultrasound evaluation of aortic insufficiency using half-pressure time. Absence of arterial rigidity influence].

    PubMed

    Kalotka-Bratek, H; Drobinski, G; Klimczak, K; Busquet, P; Fraysse, J B; Bejean-Lebuisson, A; Grosgogeat, Y

    1989-02-01

    In 20 patients with pure aortic regurgitation we studied the relationship between the severity of regurgitation, as assessed haemodynamically by the percentage of leakage (%L), and the half-pressure (T 1/2 P) and half-velocity (T 1/2 V) times, as obtained from doppler aortic blood velocity curves, taking into account the rigidity of the systemic vascular circuit characterized by the pressure wave propagation velocity (PWPV). The systemic arterial circuit was supple in 14 patients (PWPV less than 7.5 m/sec) and rigid in 6 patients (PWPV greater than 7.5 m/sec). The regression slopes between %L and T 1/2 P and between %L and T 1/2 V were calculated with their confidence limits in the 14 patients with supple arteries. The 6 patients with rigid arteries fitted into this nomogram, thus demonstrating that systemic arterial rigidity makes no difference in the relationship between %L and doppler indices. The half-velocity and half-pressure times measured by doppler ultrasound were acquired from a velocity signal directly determined by the aortic regurgitation, without any detectable effect of vascular circuit rigidity. Being equivalent by nature to the signal decrease time constant, they are independent of the absolute protodiastolic value of diastolic pressure gradient or blood flow velocity. For this reason these two doppler parameters are reliable to evaluate the severity of aortic regurgitation.

  9. [Non-rigid medical image registration based on mutual information and thin-plate spline].

    PubMed

    Cao, Guo-gang; Luo, Li-min

    2009-01-01

    To get precise and complete details, the contrast in different images is needed in medical diagnosis and computer assisted treatment. The image registration is the basis of contrast, but the regular rigid registration does not satisfy the clinic requirements. A non-rigid medical image registration method based on mutual information and thin-plate spline was present. Firstly, registering two images globally based on mutual information; secondly, dividing reference image and global-registered image into blocks and registering them; then getting the thin-plate spline transformation according to the shift of blocks' center; finally, applying the transformation to the global-registered image. The results show that the method is more precise than the global rigid registration based on mutual information and it reduces the complexity of getting control points and satisfy the clinic requirements better by getting control points of the thin-plate transformation automatically.

  10. Rigid Body Modes Influence On Microvibration Analysis-Application To Swarm

    NASA Astrophysics Data System (ADS)

    Laduree, G.; Fransen, S.; Baldesi, G.; Pflieger, I.

    2012-07-01

    Microvibrations are defined as low level mechanical disturbances affecting payload performance, generated by mobile parts or mechanism operating on-board the spacecraft, like momentum or reaction wheels, pointing mechanism, cryo-coolers or thrusters. The disturbances caused by these sources are transmitted through the spacecraft structure and excite modes of that structure or elements of the payload impacting its performance (e.g. Line of sight rotations inducing some image quality degradation). The dynamic interaction between these three elements (noise source, spacecraft structure and sensitive receiver) makes the microvibration prediction a delicate problem. Microvibration sources are generally of concern in the frequency range from a few Hz to 1000 Hz. However, in some specific cases, high stability at lower frequencies might be requested. This is the case of the SWARM mission, whose objectives are to provide the best ever survey of the geomagnetic field and its temporal evolution as well as supplementary information for studying the interaction of the magnetic field with other physical quantities describing the Earth system (e.g. ocean circulation). Among its instruments, SWARM is embarking a very sensitive 6-axis accelerometer in the low frequency range (10-8 m/s2 or rad/s2 between 10-4 and 0.1 Hz) located at its Centre of Gravity and an Absolute Scalar Magnetometer located at the tip of a boom far from the spacecraft body. The ASM performs its measurements by rotating an alternative magnetic field around its main axis thanks to a piezo-electric motor. This repeated disturbance might generate some pollution of the accelerometer science data. The objective of this work is to focus on the interaction of the rigid body mode calculation method with the elastic contribution of the normal modes excited by the noise source frequency content. It has indeed been reported in the past that NASTRAN Lanczos rigid body modes may lead to inaccurate rigid-body accelerations

  11. Astronaut mass measurement using linear acceleration method and the effect of body non-rigidity

    NASA Astrophysics Data System (ADS)

    Yan, Hui; Li, LuMing; Hu, ChunHua; Chen, Hao; Hao, HongWei

    2011-04-01

    Astronaut's body mass is an essential factor of health monitoring in space. The latest mass measurement device for the International Space Station (ISS) has employed a linear acceleration method. The principle of this method is that the device generates a constant pulling force, and the astronaut is accelerated on a parallelogram motion guide which rotates at a large radius to achieve a nearly linear trajectory. The acceleration is calculated by regression analysis of the displacement versus time trajectory and the body mass is calculated by using the formula m= F/ a. However, in actual flight, the device is instable that the deviation between runs could be 6-7 kg. This paper considers the body non-rigidity as the major cause of error and instability and analyzes the effects of body non-rigidity from different aspects. Body non-rigidity makes the acceleration of the center of mass (C.M.) oscillate and fall behind the point where force is applied. Actual acceleration curves showed that the overall effect of body non-rigidity is an oscillation at about 7 Hz and a deviation of about 25%. To enhance body rigidity, better body restraints were introduced and a prototype based on linear acceleration method was built. Measurement experiment was carried out on ground on an air table. Three human subjects weighing 60-70 kg were measured. The average variance was 0.04 kg and the average measurement error was 0.4%. This study will provide reference for future development of China's own mass measurement device.

  12. Rigid zeolite containing polyurethane foams

    DOEpatents

    Frost, Charles B.

    1985-01-01

    A closed cell rigid polyurethane foam has been prepared which contains up to about 60% by weight of molecular sieves capable of sorbing molecules with effective critical diameters of up to about 10 .ANG.. The molecular sieve component of the foam can be preloaded with catalysts or with reactive compounds that can be released upon activation of the foam to control and complete crosslinking after the foam is formed. The foam can also be loaded with water or other flame-retarding agents, after completion. Up to about 50% of the weight of the isocyanate component of the foam can be replaced by polyimide resin precursors for incorporation into the final polymeric network.

  13. Rigid zeolite containing polyurethane foams

    DOEpatents

    Frost, C.B.

    1984-05-18

    A closed cell rigid polyurethane foam has been prepared which contains up to about 60% by weight of molecular sieves capable of sorbing molecules with effective critical diameters of up to about 10 A. The molecular sieve component of the foam can be preloaded with catalysts or with reactive compounds that can be released upon activation of the foam to control and complete crosslinking after the foam is formed. The foam can also be loaded with water or other flame-retarding agents, after completion. Up to about 50% of the weight of the isocyanate component of the foam can be replaced by polyimide resin precursors for incorporation into the final polymeric network.

  14. A study of a rigid frame highway bridge in Virginia.

    DOT National Transportation Integrated Search

    1975-01-01

    This report describes the experimental and analytical study of a rigid frame highway bridge conducted under the auspices of the Federal Highway Administration and the Virginia Highway & Transportation Research Council. Data collected during the exper...

  15. Template-Based 3D Reconstruction of Non-rigid Deformable Object from Monocular Video

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Peng, Xiaodong; Zhou, Wugen; Liu, Bo; Gerndt, Andreas

    2018-06-01

    In this paper, we propose a template-based 3D surface reconstruction system of non-rigid deformable objects from monocular video sequence. Firstly, we generate a semi-dense template of the target object with structure from motion method using a subsequence video. This video can be captured by rigid moving camera orienting the static target object or by a static camera observing the rigid moving target object. Then, with the reference template mesh as input and based on the framework of classical template-based methods, we solve an energy minimization problem to get the correspondence between the template and every frame to get the time-varying mesh to present the deformation of objects. The energy terms combine photometric cost, temporal and spatial smoothness cost as well as as-rigid-as-possible cost which can enable elastic deformation. In this paper, an easy and controllable solution to generate the semi-dense template for complex objects is presented. Besides, we use an effective iterative Schur based linear solver for the energy minimization problem. The experimental evaluation presents qualitative deformation objects reconstruction results with real sequences. Compare against the results with other templates as input, the reconstructions based on our template have more accurate and detailed results for certain regions. The experimental results show that the linear solver we used performs better efficiency compared to traditional conjugate gradient based solver.

  16. Mat-like flexible thermoelectric system based on rigid inorganic bulk materials

    NASA Astrophysics Data System (ADS)

    Park, Hwanjoo; Kim, Donggyu; Eom, Yoomin; Wijethunge, Dimuthu; Hwang, Junphil; Kim, Hoon; Kim, Woochul

    2017-12-01

    This paper reports on a mat-like flexible thermoelectric system (FTES) based on rigid inorganic bulk materials, i.e. Bi-Te compounds. Inorganic bulk materials exhibit higher thermoelectric performance and can create a larger temperature drop due to their considerable height compared with organics and printable inorganics, meaning the FTES can produce an impressive power output. We show that the FTES, wherein both a thermoelectric module and a heat sink are integrated, is flexible enough to be adapted to any irregularly shaped surface. In the FTES, p- and n-type legs composed of a thermoelectric module are placed inside holders, which are connected to one another using flexible wires. Powered by a portable battery, the FTES was used to refrigerate human skin. As a result, a temperature drop of approximately 4 K was experimentally demonstrated, which humans felt as ‘cold’ or ‘very cold’, based on analysis. This indicates the feasibility of using the proposed FTES to control the temperature of the human body, even when using a portable battery. This was also applied to body heat harvesting. The FTES generated approximately 88 µW of power, which is sufficient to operate most wearable and/or implantable sensors. Our analysis based on human thermoregulatory modeling indicates that both refrigeration and power generation capacity can be further enhanced by improving the thermal contact between the FTES and human skin. The FTES shows potential for wearable refrigeration and body heat harvesting.

  17. Attitude dynamics simulation subroutines for systems of hinge-connected rigid bodies with nonrigid appendages

    NASA Technical Reports Server (NTRS)

    Fleischer, G. E.; Likins, P. W.

    1975-01-01

    Three computer subroutines designed to solve the vector-dyadic differential equations of rotational motion for systems that may be idealized as a collection of hinge-connected rigid bodies assembled in a tree topology, with an optional flexible appendage attached to each body are reported. Deformations of the appendages are mathematically represented by modal coordinates and are assumed small. Within these constraints, the subroutines provide equation solutions for (1) the most general case of unrestricted hinge rotations, with appendage base bodies nominally rotating at a constant speed, (2) the case of unrestricted hinge rotations between rigid bodies, with the restriction that those rigid bodies carrying appendages are nominally nonspinning, and (3) the case of small hinge rotations and nominally nonrotating appendages. Sample problems and their solutions are presented to illustrate the utility of the computer programs.

  18. Development and evaluation of thin semi-rigid cables for superconducting detectors

    NASA Astrophysics Data System (ADS)

    Kasai, Soichi; Kushino, Akihiro

    2015-03-01

    We are developing semi-rigid cables for accurate readout of superconducting radiation/particle detectors and other low temperature experiments. The center conductor with a diameter of 0.86 mm is separated with seamless metal outer conductor by dielectric material, polytetrafluoroethylene. We used various metal materials with low thermal conductivity for the electrical conductors such as stainless-steel, cupro-nickel, brass, beryllium-copper, phosphor-bronze, niobium-titanium, and niobium. In addition to the conventional semi-rigid cables, low-pass-filter-type cables were manufactured and evaluated to cut the high frequency noise into superconducting detectors. We measured their low thermal conductance and attenuation property up to 10GHz below the liquid helium temperature.

  19. Designing heavy metal oxide glasses with threshold properties from network rigidity

    NASA Astrophysics Data System (ADS)

    Chakraborty, Shibalik; Boolchand, P.; Malki, M.; Micoulaut, M.

    2014-01-01

    Here, we show that a new class of glasses composed of heavy metal oxides involving transition metals (V2O5-TeO2) can surprisingly be designed from very basic tools using topology and rigidity of their underlying molecular networks. When investigated as a function of composition, such glasses display abrupt changes in network packing and enthalpy of relaxation at Tg, underscoring presence of flexible to rigid elastic phase transitions. We find that these elastic phases are fully consistent with polaronic nature of electronic conductivity at high V2O5 content. Such observations have new implications for designing electronic glasses which differ from the traditional amorphous electrolytes having only mobile ions as charge carriers.

  20. Parameters estimation of sandwich beam model with rigid polyurethane foam core

    NASA Astrophysics Data System (ADS)

    Barbieri, Nilson; Barbieri, Renato; Winikes, Luiz Carlos

    2010-02-01

    In this work, the physical parameters of sandwich beams made with the association of hot-rolled steel, Polyurethane rigid foam and High Impact Polystyrene, used for the assembly of household refrigerators and food freezers are estimated using measured and numeric frequency response functions (FRFs). The mathematical models are obtained using the finite element method (FEM) and the Timoshenko beam theory. The physical parameters are estimated using the amplitude correlation coefficient and genetic algorithm (GA). The experimental data are obtained using the impact hammer and four accelerometers displaced along the sample (cantilevered beam). The parameters estimated are Young's modulus and the loss factor of the Polyurethane rigid foam and the High Impact Polystyrene.

  1. Designing heavy metal oxide glasses with threshold properties from network rigidity.

    PubMed

    Chakraborty, Shibalik; Boolchand, P; Malki, M; Micoulaut, M

    2014-01-07

    Here, we show that a new class of glasses composed of heavy metal oxides involving transition metals (V2O5-TeO2) can surprisingly be designed from very basic tools using topology and rigidity of their underlying molecular networks. When investigated as a function of composition, such glasses display abrupt changes in network packing and enthalpy of relaxation at Tg, underscoring presence of flexible to rigid elastic phase transitions. We find that these elastic phases are fully consistent with polaronic nature of electronic conductivity at high V2O5 content. Such observations have new implications for designing electronic glasses which differ from the traditional amorphous electrolytes having only mobile ions as charge carriers.

  2. Rigid indented cylindrical cathode for X-ray tube

    DOEpatents

    Hudgens, Claude R.

    1985-01-01

    A cathode assembly for a vacuum tube includes a wire filament, a straight bular anode parallel to and surrounding the wire filament, and insulating spacers for rigidly fastening the filament with respect to the anode, and with one side of the anode indented or flattened such that only one portion of the anode is heated to emitting temperatures by the filament.

  3. Dynamic Non-Rigid Objects Reconstruction with a Single RGB-D Sensor

    PubMed Central

    Zuo, Xinxin; Du, Chao; Wang, Runxiao; Zheng, Jiangbin; Yang, Ruigang

    2018-01-01

    This paper deals with the 3D reconstruction problem for dynamic non-rigid objects with a single RGB-D sensor. It is a challenging task as we consider the almost inevitable accumulation error issue in some previous sequential fusion methods and also the possible failure of surface tracking in a long sequence. Therefore, we propose a global non-rigid registration framework and tackle the drifting problem via an explicit loop closure. Our novel scheme starts with a fusion step to get multiple partial scans from the input sequence, followed by a pairwise non-rigid registration and loop detection step to obtain correspondences between neighboring partial pieces and those pieces that form a loop. Then, we perform a global registration procedure to align all those pieces together into a consistent canonical space as guided by those matches that we have established. Finally, our proposed model-update step helps fixing potential misalignments that still exist after the global registration. Both geometric and appearance constraints are enforced during our alignment; therefore, we are able to get the recovered model with accurate geometry as well as high fidelity color maps for the mesh. Experiments on both synthetic and various real datasets have demonstrated the capability of our approach to reconstruct complete and watertight deformable objects. PMID:29547562

  4. Mental set and creative thought in social conflict: threat rigidity versus motivated focus.

    PubMed

    De Dreu, Carsten K W; Nijstad, Bernard A

    2008-09-01

    According to the traditional threat-rigidity reasoning, people in social conflict will be less flexible, less creative, more narrow-minded, and more rigid in their thinking when they adopt a conflict rather than a cooperation mental set. The authors propose and test an alternative, motivated focus account that better fits existing evidence. The authors report experimental results inconsistent with a threat-rigidity account, but supporting the idea that people focus their cognitive resources on conflict-related material more when in a conflict rather than a cooperation mental set: Disputants with a conflict (cooperation) set have broader (smaller) and more (less) inclusive cognitive categories when the domain of thought is (un)related to conflict (Experiment 1a-1b). Furthermore, they generate more, and more original competition tactics (Experiments 2-4), especially when they have low rather than high need for cognitive closure. Implications for conflict theory, for motivated information processing, and creativity research are discussed.

  5. Vertical dimensional stability and rigidity of occlusal registration materials.

    PubMed

    Walker, Mary P; Wu, Edis; Heckman, M Elizabeth; Alderman, Nicholas

    2009-01-01

    Dimensionally accurate occlusal registration records are essential for restorative dentistry; moreover, since records are not used immediately or may be used more than once, the registration material should exhibit accuracy over time (a concept known as dimensional stability). It has been speculated that materials with increased hardness or rigidity should produce more accurate registration records due to an increased resistance to distortion. This study compared the rigidity and associated dimensional accuracy of a recently marketed bisacrylic occlusal registration material and a vinyl polysiloxane (VPS). Maxillary and mandibular typodont arches were mounted on a plasterless articulator from which teeth No. 3, 13, and 15 had been removed to simulate edentulous spaces. After preparing teeth No. 2, 4, 12, and 14 as bridge abutments, the remaining teeth were equilibrated selectively to produce even anterior contact. Four digital photographs were taken to make vertical interarch measurements at four locations (teeth No. 3, 7, 10, and 14). Following initial photos (controls), 10 interocclusal records were made using each registration material, with material placed only in the segments in which teeth were prepared. The records were used for mounting the maxillary arch against the mandibular arch after 48, 72, and 120 hours. There were significant effects on vertical dimensional change related to arch location, material, and mounting time. Both materials demonstrated significantly larger posterior vertical openings than anterior vertical openings, while the bisacrylate produced a larger posterior opening than VPS at 48 and 72 hours and a larger anterior opening at all mounting times. There also was a significant difference in hardness/rigidity due to material and measurement time; at all measurement times, bisacrylate exhibited a significantly higher hardness number.

  6. Rigid Facial Motion Influences Featural, But Not Holistic, Face Processing

    PubMed Central

    Xiao, Naiqi; Quinn, Paul C.; Ge, Liezhong; Lee, Kang

    2012-01-01

    We report three experiments in which we investigated the effect of rigid facial motion on face processing. Specifically, we used the face composite effect to examine whether rigid facial motion influences primarily featural or holistic processing of faces. In Experiments 1, 2, and 3, participants were first familiarized with dynamic displays in which a target face turned from one side to another; then at test, participants judged whether the top half of a composite face (the top half of the target face aligned or misaligned with the bottom half of a foil face) belonged to the target face. We compared performance in the dynamic condition to various static control conditions in Experiments 1, 2, and 3, which differed from each other in terms of the display order of the multiple static images or the inter stimulus interval (ISI) between the images. We found that the size of the face composite effect in the dynamic condition was significantly smaller than that in the static conditions. In other words, the dynamic face display influenced participants to process the target faces in a part-based manner and consequently their recognition of the upper portion of the composite face at test became less interfered with by the aligned lower part of the foil face. The findings from the present experiments provide the strongest evidence to date to suggest that the rigid facial motion mainly influences facial featural, but not holistic, processing. PMID:22342561

  7. Effect of Ion Rigidity on Physical Properties of Ionic Liquids Studied by Molecular Dynamics Simulation.

    PubMed

    Ramírez-González, Pedro E; Ren, Gan; Saielli, Giacomo; Wang, Yanting

    2016-06-30

    In this work, we have performed molecular dynamics (MD) simulations to compare the structural and dynamical properties of three ionic liquids (ILs), 1-ethyl-3-methyl-imidazolium tetrafluorborate ([EMI(+)][BF4(-)]), 1,1'-dimethyl-4,4'-bipyridinium bis(tetrafluorborate) ([VIO(2+)][BF4(-)]2), and 1,1'-dimethyl-4,4'-bipyridinium bis(trifluoromethylsulfonyl)imide (bistriflimide in short) ([VIO(2+)][Tf2N(-)]2), aiming to discover the influence of ion rigidity on the physical properties of ILs. [VIO(2+)] is more rigid than [EMI(+)], and [BF4(-)] is more rigid than [Tf2N(-)]. [VIO(2+)][BF4(-)]2 has an anion distribution different from the other two by the higher and sharper peaks in the cation-anion radial distribution functions, reflecting a close-packed local structure of anions around cations. [VIO(2+)][BF4(-)]2 and [VIO(2+)][Tf2N(-)]2 have similar dynamics much slower than [EMI(+)][BF4(-)], and [VIO(2+)][Tf2N(-)]2 shows a more isotropic molecular distribution than [VIO(2+)][BF4(-)]2 and [EMI(+)][BF4(-)]. Additionally, we have simulated two modified viologen-based ILs to reinforce our interpretations. We conclude from the above simulation results that the rigidity of anions influences the alignment of cations and that the rigidity of cations shows a large obstacle to their rotational capacity. Moreover, we have observed a slower diffusion of [VIO(2+)][BF4(-)]2 due to the electrostatic correlations, which stabilizes the ion-cage effect.

  8. 13. VIEW OF CAUSEWAY, LOOKING EAST, PROFILING DETAILS OF RIGID ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. VIEW OF CAUSEWAY, LOOKING EAST, PROFILING DETAILS OF RIGID FRAME SPAN OVER CANAL STREET, AND SHOWING STEEL RIBS AND FLOOR BEANS ENCASED IN CONCRETE - Notre Dame Bridge, Spanning Merrimack River on Bridge Street, Manchester, Hillsborough County, NH

  9. Real-time motion compensated patient positioning and non-rigid deformation estimation using 4-D shape priors.

    PubMed

    Wasza, Jakob; Bauer, Sebastian; Hornegger, Joachim

    2012-01-01

    Over the last years, range imaging (RI) techniques have been proposed for patient positioning and respiration analysis in motion compensation. Yet, current RI based approaches for patient positioning employ rigid-body transformations, thus neglecting free-form deformations induced by respiratory motion. Furthermore, RI based respiration analysis relies on non-rigid registration techniques with run-times of several seconds. In this paper we propose a real-time framework based on RI to perform respiratory motion compensated positioning and non-rigid surface deformation estimation in a joint manner. The core of our method are pre-procedurally obtained 4-D shape priors that drive the intra-procedural alignment of the patient to the reference state, simultaneously yielding a rigid-body table transformation and a free-form deformation accounting for respiratory motion. We show that our method outperforms conventional alignment strategies by a factor of 3.0 and 2.3 in the rotation and translation accuracy, respectively. Using a GPU based implementation, we achieve run-times of 40 ms.

  10. Ion-conduction and rigidity/flexibility of glasses

    NASA Astrophysics Data System (ADS)

    Novita, D. I.; Boolchand, P.; Malki, M.; Micoulaut, M.

    2007-03-01

    The (AgI)x(AgPO3)1-x solid electrolyte glass system has been examined extensively although a consensus on the increase of electrical conductivity with x data has been elusive. Here we show that the variability of the data is likely due to water contamination. Our work is on specifically prepared dry samples which display glass transition temperatures Tg(x) that are at least 50 to 100 C higher than those reported hitherto. In Raman scattering the frequency of the P-Ot bonds in PO4 tetrahedra of long chains is found to systematically red-shift with increasing x, and to display thresholds near x= xc(1) =0.095(3)(stress-transition) and x =xc(2) = 0.379(5)(rigidity transition). Calorimetric measurements show a reversibility window in the 0.09 < x < 0.38 range. Room temperature electrical conductivity, σ(x), increases with x to display thresholds near xc(1) and xc(2), and a logarithmic increase at x> xc(2) with a power-law μ = 1.78(10) that is in good agreement with theoretical predictions^1. Properties of flexibility and rigidity of backbones commonplace in covalent systems^2 is a concept that extends to solid electrolyte glasses as well. ^1Richard Zallen, Physics of Amorphous Solids ^2 P. Boolchand et al. Phil. Mag 85, 3823 (2005)

  11. Rapid maxillary distraction protocol utilizing the halo distraction system and rigid internal fixation.

    PubMed

    Baker, Stephen B; Reid, Russell R; Burkey, Brooke; Bartlett, Scott P

    2007-09-01

    To shorten head frame wear time associated with external halo distraction (HD), we have adapted a protocol for maxillary distraction with the halo system that integrates plate fixation. All patients had a history of cleft lip and/or palate and maxillary retrusion > or = 8 mm. Five patients treated with this protocol and followed for at least 1 year were included in this study. The protocol included a 3-day latency period, variable maxillary distraction, and removal of the halo device with simultaneous rigid internal fixation. Two patients had a variable period of maxillomandibular fixation (MMF), which maintained the maxillary advancement and idealized intercuspal position while permitting further callus maturation. Cephalographs were obtained preoperatively, immediately following distractor removal, and 1 year after rigid internal fixation. The mean age at time of surgery was 18.7 years. The maxillary deficiency ranged from 8 to 15 mm (mean = 10.6 mm). All five patients demonstrated excellent occlusion. Cephalometric analysis 1-year post rigid internal fixation revealed minimal (<1 mm) skeletal relapse. Rapid maxillary distraction followed by MMF to maintain maxillary advancement may reduce halo device wear to 1 to 2 weeks. MMF optimizes occlusion by forcing the maxillary teeth into maximal intercuspal position. Rigid fixation is not only associated with less long-term relapse compared to nonrigid forms of fixation, but also minimizes the incidence of nonunion. This treatment protocol provides the advancement possible with distraction osteogenesis and the accuracy of orthognathic surgery, thereby minimizing external head frame wear.

  12. CRP - VD Tube & Closure -  Unit Non-Reclosable Packaging Rigid

    EPA Pesticide Factsheets

    This is a unit-dose non-reclosable rigid package. The package consists of a tube and a closure that is permanently attached to the tube neck. The package is opened by pushing down on the closure and simultaneously turning it counterclockwise.

  13. Quantum angular momentum diffusion of rigid bodies

    NASA Astrophysics Data System (ADS)

    Papendell, Birthe; Stickler, Benjamin A.; Hornberger, Klaus

    2017-12-01

    We show how to describe the diffusion of the quantized angular momentum vector of an arbitrarily shaped rigid rotor as induced by its collisional interaction with an environment. We present the general form of the Lindblad-type master equation and relate it to the orientational decoherence of an asymmetric nanoparticle in the limit of small anisotropies. The corresponding diffusion coefficients are derived for gas particles scattering off large molecules and for ambient photons scattering off dielectric particles, using the elastic scattering amplitudes.

  14. Muscular MRI-based algorithm to differentiate inherited myopathies presenting with spinal rigidity.

    PubMed

    Tordjman, Mickael; Dabaj, Ivana; Laforet, Pascal; Felter, Adrien; Ferreiro, Ana; Biyoukar, Moustafa; Law-Ye, Bruno; Zanoteli, Edmar; Castiglioni, Claudia; Rendu, John; Beroud, Christophe; Chamouni, Alexandre; Richard, Pascale; Mompoint, Dominique; Quijano-Roy, Susana; Carlier, Robert-Yves

    2018-05-25

    Inherited myopathies are major causes of muscle atrophy and are often characterized by rigid spine syndrome, a clinical feature designating patients with early spinal contractures. We aim to present a decision algorithm based on muscular whole body magnetic resonance imaging (mWB-MRI) as a unique tool to orientate the diagnosis of each inherited myopathy long before the genetically confirmed diagnosis. This multicentre retrospective study enrolled 79 patients from referral centres in France, Brazil and Chile. The patients underwent 1.5-T or 3-T mWB-MRI. The protocol comprised STIR and T1 sequences in axial and coronal planes, from head to toe. All images were analyzed manually by multiple raters. Fatty muscle replacement was evaluated on mWB-MRI using both the Mercuri scale and statistical comparison based on the percentage of affected muscle. Between February 2005 and December 2015, 76 patients with genetically confirmed inherited myopathy were included. They were affected by Pompe disease or harbored mutations in RYR1, Collagen VI, LMNA, SEPN1, LAMA2 and MYH7 genes. Each myopathy had a specific pattern of affected muscles recognizable on mWB-MRI. This allowed us to create a novel decision algorithm for patients with rigid spine syndrome by segregating these signs. This algorithm was validated by five external evaluators on a cohort of seven patients with a diagnostic accuracy of 94.3% compared with the genetic diagnosis. We provide a novel decision algorithm based on muscle fat replacement graded on mWB-MRI that allows diagnosis and differentiation of inherited myopathies presenting with spinal rigidity. • Inherited myopathies are rare, diagnosis is challenging and genetic tests require specialized centres and often take years. • Inherited myopathies are often characterized by spinal rigidity. • Whole body magnetic resonance imaging is a unique tool to orientate the diagnosis of each inherited myopathy presenting with spinal rigidity. • Each inherited

  15. Flexural rigidity of the Basin and Range-Colorado Plateau-Rocky Mountain transition from coherence analysis of gravity and topography

    NASA Technical Reports Server (NTRS)

    Lowery, Anthony R.; Smith, Robert B.

    1994-01-01

    Stochastic inversion for flexural loads and flexural rigidity of the continental elastic layer can be accomplished most effectively by using the coherence of gravity and topography. However, the spatial resolution of coherence analysis has been limited by use of two-dimensional periodogram spectra from very large (greater than 10(exp 5)sq km) windows that generally include multiple tectonic features. Using a two-dimensional spectral estimator based on the maximum entropy method, the spatial resolution of flexural proerties can be enhanced by a factor of 4 or more, enabling more detailed analysis at the scale of individual tectonic features. This new approach is used to map the spatial variation of flexural rigidity along the Basin and Range transition to the Colorado Plateau and Middle Rocky Mountains physiographic provinces. Large variations in flexural isostatic responses are found, with rigidities ranging from as low as 8.7 x 10(exp 20) N m (elastic thickness (T(sub e) = 4.6 km) in the Basin and Range to as high as 4.1 x 10(exp 24) N m T(sub e) = 77 km) in the Middle Rocky Mountains. These results compare favorably woith independent determinations of flexural rigidity in the region. Areas of low flexural rigidity correlate strongly with areas of high surface heat flow, as is expected from the contingence of flexural rigidity on a temperature-dependent flow law. Also, late Cenozoic normal faults with large displacements are found primarily in area of low flexural rigidity region. The highest flexural rigidity is found within the Archean Wyoming craton, where evidence suggests that deeply rooted cratonic lithosphere may play a role in determining the distribution of tectonism at the surface.

  16. A rigidly rotating magnetosphere model for circumstellar emission from magnetic OB stars

    NASA Astrophysics Data System (ADS)

    Townsend, R. H. D.; Owocki, S. P.

    2005-02-01

    We present a semi-analytical approach for modelling circumstellar emission from rotating hot stars with a strong dipole magnetic field tilted at an arbitrary angle to the rotation axis. By assuming the rigid-field limit in which material driven (e.g. in a wind outflow) from the star is forced to remain in strict rigid-body corotation, we are able to solve for the effective centrifugal-plus-gravitational potential along each field line, and thereby identify the location of potential minima where material is prone to accumulate. Applying basic scalings for the surface mass flux of a radiatively driven stellar wind, we calculate the circumstellar density distribution that obtains once ejected plasma settles into hydrostatic stratification along field lines. The resulting accumulation surface resembles a rigidly rotating, warped disc, tilted such that its average surface normal lies between the rotation and magnetic axes. Using a simple model of the plasma emissivity, we calculate time-resolved synthetic line spectra for the disc. Initial comparisons show an encouraging level of correspondence with the observed rotational phase variations of Balmer-line emission profiles from magnetic Bp stars such as σ Ori E.

  17. Total absorption peak by use of a rigid frame porous layer backed by a rigid multi-irregularities grating.

    PubMed

    Groby, J-P; Lauriks, W; Vigran, T E

    2010-05-01

    The acoustic properties of a low resistivity porous layer backed by a rigid plate containing periodic rectangular irregularities, creating a multicomponent diffraction gratings, are investigated. Numerical and experimental results show that the structure possesses a total absorption peak at the frequency of the modified mode of the layer, when designed as proposed in the article. These results are explained by an analysis of the acoustic response of the whole structure and especially by the modal analysis of the configuration. When more than one irregularity per spatial period is considered, additional higher frequency peaks are observed.

  18. Partners in Self-Sufficiency Guidebook.

    ERIC Educational Resources Information Center

    Department of Housing and Urban Development, Washington, DC. Office of Policy Development and Research.

    This guidebook is for community leaders who are implementing the Federal Partners in Self-Sufficiency (PS-S) program, a community-based approach to service delivery that helps families get off welfare. The program offers a comprehensive package of services including housing, education, child care, transportation, counseling, and job training and…

  19. Matrix Rigidity Regulates Cancer Cell Growth by Modulating Cellular Metabolism and Protein Synthesis

    PubMed Central

    Tilghman, Robert W.; Blais, Edik M.; Cowan, Catharine R.; Sherman, Nicholas E.; Grigera, Pablo R.; Jeffery, Erin D.; Fox, Jay W.; Blackman, Brett R.; Tschumperlin, Daniel J.; Papin, Jason A.; Parsons, J. Thomas

    2012-01-01

    Background Tumor cells in vivo encounter diverse types of microenvironments both at the site of the primary tumor and at sites of distant metastases. Understanding how the various mechanical properties of these microenvironments affect the biology of tumor cells during disease progression is critical in identifying molecular targets for cancer therapy. Methodology/Principal Findings This study uses flexible polyacrylamide gels as substrates for cell growth in conjunction with a novel proteomic approach to identify the properties of rigidity-dependent cancer cell lines that contribute to their differential growth on soft and rigid substrates. Compared to cells growing on more rigid/stiff substrates (>10,000 Pa), cells on soft substrates (150–300 Pa) exhibited a longer cell cycle, due predominantly to an extension of the G1 phase of the cell cycle, and were metabolically less active, showing decreased levels of intracellular ATP and a marked reduction in protein synthesis. Using stable isotope labeling of amino acids in culture (SILAC) and mass spectrometry, we measured the rates of protein synthesis of over 1200 cellular proteins under growth conditions on soft and rigid/stiff substrates. We identified cellular proteins whose syntheses were either preferentially inhibited or preserved on soft matrices. The former category included proteins that regulate cytoskeletal structures (e.g., tubulins) and glycolysis (e.g., phosphofructokinase-1), whereas the latter category included proteins that regulate key metabolic pathways required for survival, e.g., nicotinamide phosphoribosyltransferase, a regulator of the NAD salvage pathway. Conclusions/Significance The cellular properties of rigidity-dependent cancer cells growing on soft matrices are reminiscent of the properties of dormant cancer cells, e.g., slow growth rate and reduced metabolism. We suggest that the use of relatively soft gels as cell culture substrates would allow molecular pathways to be studied under

  20. Three dimensional modeling of rigid pavement : executive summary, February 1995.

    DOT National Transportation Integrated Search

    1995-02-17

    A finite-element program has been developed to model the response of rigid pavement to both static loads and temperature changes. The program is fully three-dimensional and incorporates not only the common twenty-node brick element but also a thin in...

  1. Three-dimensional modeling of rigid pavement : final report, September 1995.

    DOT National Transportation Integrated Search

    1995-02-17

    A finite-element program has been developed to model the response of rigid pavement to both static loads and temperature changes. The program is fully three-dimensional and incorporates not only the common twenty-node brick element but also a thin in...

  2. 21 CFR 164.120 - Shelled nuts in rigid or semirigid containers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION TREE NUT AND PEANUT PRODUCTS Requirements for Specific Standardized Tree Nut and Peanut Products § 164.120 Shelled nuts in rigid or semirigid containers. (a)-(b...

  3. 21 CFR 164.120 - Shelled nuts in rigid or semirigid containers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION TREE NUT AND PEANUT PRODUCTS Requirements for Specific Standardized Tree Nut and Peanut Products § 164.120 Shelled nuts in rigid or semirigid containers. (a)-(b...

  4. 21 CFR 164.120 - Shelled nuts in rigid or semirigid containers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION TREE NUT AND PEANUT PRODUCTS Requirements for Specific Standardized Tree Nut and Peanut Products § 164.120 Shelled nuts in rigid or semirigid containers. (a)-(b...

  5. 21 CFR 164.120 - Shelled nuts in rigid or semirigid containers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION TREE NUT AND PEANUT PRODUCTS Requirements for Specific Standardized Tree Nut and Peanut Products § 164.120 Shelled nuts in rigid or semirigid containers. (a)-(b...

  6. 21 CFR 164.120 - Shelled nuts in rigid or semirigid containers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION TREE NUT AND PEANUT PRODUCTS Requirements for Specific Standardized Tree Nut and Peanut Products § 164.120 Shelled nuts in rigid or semirigid containers. (a)-(b...

  7. How soft is that pillow? The perceptual localization of the hand and the haptic assessment of contact rigidity.

    PubMed

    Pressman, Assaf; Karniel, Amir; Mussa-Ivaldi, Ferdinando A

    2011-04-27

    A new haptic illusion is described, in which the location of the mobile object affects the perception of its rigidity. There is theoretical and experimental support for the notion that limb position sense results from the brain combining ongoing sensory information with expectations arising from prior experience. How does this probabilistic state information affect one's tactile perception of the environment mechanics? In a simple estimation process, human subjects were asked to report the relative rigidity of two simulated virtual objects. One of the objects remained fixed in space and had various coefficients of stiffness. The other virtual object had constant stiffness but moved with respect to the subjects. Earlier work suggested that the perception of an object's rigidity is consistent with a process of regression between the contact force and the perceived amount of penetration inside the object's boundary. The amount of penetration perceived by the subject was affected by varying the position of the object. This, in turn, had a predictable effect on the perceived rigidity of the contact. Subjects' reports on the relative rigidity of the object are best accounted for by a probabilistic model in which the perceived boundary of the object is estimated based on its current location and on past observations. Therefore, the perception of contact rigidity is accounted for by a stochastic process of state estimation underlying proprioceptive localization of the hand.

  8. Reduction of stresses on buried rigid highway structures using the imperfect ditch method and expanded polysterene : geofoam.

    DOT National Transportation Integrated Search

    2009-01-01

    This study provides strong evidences from both numerical model analysis and in-situ test data to indicate that geofoam is an ideal elasto-plastic material to reduce vertical load on top of rigid culvert resting on a rigid foundation. The load on the ...

  9. Fast calibration of electromagnetically tracked oblique-viewing rigid endoscopes.

    PubMed

    Liu, Xinyang; Rice, Christina E; Shekhar, Raj

    2017-10-01

    The oblique-viewing (i.e., angled) rigid endoscope is a commonly used tool in conventional endoscopic surgeries. The relative rotation between its two moveable parts, the telescope and the camera head, creates a rotation offset between the actual and the projection of an object in the camera image. A calibration method tailored to compensate such offset is needed. We developed a fast calibration method for oblique-viewing rigid endoscopes suitable for clinical use. In contrast to prior approaches based on optical tracking, we used electromagnetic (EM) tracking as the external tracking hardware to improve compactness and practicality. Two EM sensors were mounted on the telescope and the camera head, respectively, with considerations to minimize EM tracking errors. Single-image calibration was incorporated into the method, and a sterilizable plate, laser-marked with the calibration pattern, was also developed. Furthermore, we proposed a general algorithm to estimate the rotation center in the camera image. Formulas for updating the camera matrix in terms of clockwise and counterclockwise rotations were also developed. The proposed calibration method was validated using a conventional [Formula: see text], 5-mm laparoscope. Freehand calibrations were performed using the proposed method, and the calibration time averaged 2 min and 8 s. The calibration accuracy was evaluated in a simulated clinical setting with several surgical tools present in the magnetic field of EM tracking. The root-mean-square re-projection error averaged 4.9 pixel (range 2.4-8.5 pixel, with image resolution of [Formula: see text] for rotation angles ranged from [Formula: see text] to [Formula: see text]. We developed a method for fast and accurate calibration of oblique-viewing rigid endoscopes. The method was also designed to be performed in the operating room and will therefore support clinical translation of many emerging endoscopic computer-assisted surgical systems.

  10. Numerical study of rigid and flexible wing shapes in hover

    NASA Astrophysics Data System (ADS)

    Shahzad, Aamer; Tian, Fang-Bao; Young, John; Lai, Joseph C. S.

    2017-04-01

    This study is focused on evaluating the aerodynamic performance of rigid and isotropic flexible wing shapes defined by the radius of the first moment of wing area ({\\bar{r}}1) at Reynolds number of 6000. An immersed boundary method was used to solve the 3D, viscous, incompressible Navier-Stokes equations, and coupled with an in-house non-linear finite element solver for fluid structure interaction simulations. Numerical simulations of flexible {\\bar{r}}1=0.43,0.53{and}0.63 wing shapes performed with a single degree of freedom flapping shows that thrust and peak lift coefficients increase with {\\bar{r}}1. Higher thrust in the {\\bar{r}}1=0.63 wing is attributed to the large induced pitch angle, and higher peak lift (compared to the rigid counterpart) results from an increase in the stroke amplitude and spanwise deformation of the wing that anchors the leading edge vortex.

  11. Global tectonic reconstructions with continuously deforming and evolving rigid plates

    NASA Astrophysics Data System (ADS)

    Gurnis, Michael; Yang, Ting; Cannon, John; Turner, Mark; Williams, Simon; Flament, Nicolas; Müller, R. Dietmar

    2018-07-01

    Traditional plate reconstruction methodologies do not allow for plate deformation to be considered. Here we present software to construct and visualize global tectonic reconstructions with deforming plates within the context of rigid plates. Both deforming and rigid plates are defined by continuously evolving polygons. The deforming regions are tessellated with triangular meshes such that either strain rate or cumulative strain can be followed. The finite strain history, crustal thickness and stretching factor of points within the deformation zones are tracked as Lagrangian points. Integrating these tools within the interactive platform GPlates enables specialized users to build and refine deforming plate models and integrate them with other models in time and space. We demonstrate the integrated platform with regional reconstructions of Cenozoic western North America, the Mesozoic South American Atlantic margin, and Cenozoic southeast Asia, embedded within global reconstructions, using different data and reconstruction strategies.

  12. Probing the limits of the rigid-intensity-shift model in differential-phase-contrast scanning transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Clark, L.; Brown, H. G.; Paganin, D. M.; Morgan, M. J.; Matsumoto, T.; Shibata, N.; Petersen, T. C.; Findlay, S. D.

    2018-04-01

    The rigid-intensity-shift model of differential-phase-contrast imaging assumes that the phase gradient imposed on the transmitted probe by the sample causes the diffraction pattern intensity to shift rigidly by an amount proportional to that phase gradient. This behavior is seldom realized exactly in practice. Through a combination of experimental results, analytical modeling and numerical calculations, using as case studies electron microscope imaging of the built-in electric field in a p-n junction and nanoscale domains in a magnetic alloy, we explore the breakdown of rigid-intensity-shift behavior and how this depends on the magnitude of the phase gradient and the relative scale of features in the phase profile and the probe size. We present guidelines as to when the rigid-intensity-shift model can be applied for quantitative phase reconstruction using segmented detectors, and propose probe-shaping strategies to further improve the accuracy.

  13. Reductions in the diurnal rigidity of anxiety predict treatment outcome in cognitive behavioral therapy for generalized anxiety disorder.

    PubMed

    Fisher, Aaron J; Newman, Michelle G

    2016-04-01

    Generalized anxiety disorder (GAD) is a chronic and disabling disorder which is characterized by worrisome mentation about future outcomes. Because the evocative stimuli in GAD are largely internally derived, the feared outcomes contained in worry episodes can be invoked--and responded to--regardless of external context. We hypothesized that individuals with GAD would be entrained to internally-regulated, fixed patterns of anxiety on a day-to-day basis and that successful therapeutic intervention would serve to mitigate this entrainment. Thus, the present study examined the constructs of flexibility and rigidity as they apply to the daily fluctuation of anxious symptoms in individuals with GAD. We aimed to demonstrate that an apparently variable system can be conceptualized as rigid when the variability maps onto stable and predictable periodic oscillations. Sixty-nine individuals completed cognitive-behavioral treatment for GAD. Average age was 36.62 years (SD = 11.56), and participants were mostly Caucasian (89.5%) and female (68.4%). Daily-diary data indicating level of anxiety on a 0 to 100-point scale and collected four times per day were subjected to spectral analysis in order to determine the spectral power attributable to daily oscillations--which was related to the degree of rigidity in daily anxiety. Diurnal rigidity decreased throughout therapy and the degree to which rigidity was reduced significantly predicted reliable change at post-treatment. Thus, symptom rigidity can be conceptualized as stable periodic fluctuation and is discernible from other metrics of volatility in repeated measures data. Moreover, diurnal rigidity is significantly reduced during treatment, facilitating flexible responding to environmental demands. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Cunnington, George R.; Knutson, Jeffrey R.

    2012-01-01

    Combined radiation and conduction heat transfer through a high-temperature, high-porosity, rigid multiple-fiber fibrous insulation was modeled using a thermal model previously used to model heat transfer in flexible single-fiber fibrous insulation. The rigid insulation studied was alumina enhanced thermal barrier (AETB) at densities between 130 and 260 kilograms per cubic meter. The model consists of using the diffusion approximation for radiation heat transfer, a semi-empirical solid conduction model, and a standard gas conduction model. The relevant parameters needed for the heat transfer model were estimated from steady-state thermal measurements in nitrogen gas at various temperatures and environmental pressures. The heat transfer modeling methodology was evaluated by comparison with standard thermal conductivity measurements, and steady-state thermal measurements in helium and carbon dioxide gases. The heat transfer model is applicable over the temperature range of 300 to 1360 K, pressure range of 0.133 to 101.3 x 10(exp 3) Pa, and over the insulation density range of 130 to 260 kilograms per cubic meter in various gaseous environments.

  15. Measurement of Spindle Rigidity by using a Magnet Loader

    NASA Astrophysics Data System (ADS)

    Yamazaki, Taku; Matsubara, Atsushi; Fujita, Tomoya; Muraki, Toshiyuki; Asano, Kohei; Kawashima, Kazuyuki

    The static rigidity of a rotating spindle in the radial direction is investigated in this research. A magnetic loading device (magnet loader) has been developed for the measurement. The magnet loader, which has coils and iron cores, generates the electromagnetic force and attracts a dummy tool attached to the spindle. However, the eddy current is generated in the dummy tool with the spindle rotation and reduces the attractive force at high spindle speed. In order to understand the magnetic flux and eddy current in the dummy tool, the electromagnetic field analysis by FEM was carried out. Grooves on the attraction surface of the dummy tool were designed to cut the eddy current flow. The dimension of the groove were decided based on the FEM analysis, and the designed tool were manufactured and tested. The test result shows that the designed tool successfully reduces the eddy current and recovers the attractive force. By using the magnet loader and the grooved tool, the spindle rigidity can be measured when the spindle rotates with a speed up to 10,000 min-1.

  16. New Forms of BRST Symmetry in Rigid Rotor

    NASA Astrophysics Data System (ADS)

    Rai, Sumit Kumar; Mandal, Bhabani Prasad

    We derive the different forms of BRST symmetry by using the Batalin-Fradkin-Vilkovisky formalism in a rigid rotor. The so-called "dual-BRST" symmetry is obtained from the usual BRST symmetry by making a canonical transformation in the ghost sector. On the other hand, a canonical transformation in the sector involving Lagrange multiplier and its corresponding momentum leads to a new form of BRST as well as dual-BRST symmetry.

  17. Bio-based rigid polyurethane foam from liquefied products of wood in the presence of polyhydric alcohols

    Treesearch

    Zhifeng Zheng; Hui Pan; Yuanbo Huang; Chung Y. Hse

    2011-01-01

    Rigid polyurethane foams were prepared from the liquefied wood polyols, which was obtained by the liquefaction of southern pine wood in the presence of polyhydric alcohols with sulfuric acid catalyst by using microwave-assistant as an energy source. The properties of liquefied biomass-based polyols and the rigid polyurethane foams were investigated. The results...

  18. Knowledge-In-Action: An Example with Rigid Body Motion

    ERIC Educational Resources Information Center

    Da Costa, Sayonara Salvador Cabral; Moreira, Marco Antonio

    2005-01-01

    This paper reports the analysis of the resolution of a paper-and-pencil problem, by eight undergraduate students majoring in engineering (six) and physics (two) at the Pontifcia Universidade Catlica do Rio Grande do Sul, in Porto Alegre, Brazil. The problem concerns kinetics of a rigid body, and the analysis was done in the light of Johnson-Lairds…

  19. The rigidity and mobility of screw dislocations in a thin film

    NASA Astrophysics Data System (ADS)

    Wang, Fei

    2018-07-01

    An equation of screw dislocations in a thin film is derived for arbitrary boundary conditions. The boundary conditions can be the free surface, the fixed surface or the gradient loading imposed on the surface. The new equation makes it possible to study changes in the dislocation structure under various gradient stress applied to the surface. The rigidity and mobility of screw dislocations in a thin film are explored by using the equation. It is found that the screw dislocation core in a thin film is like a Hookean body with a specific shear stress applied to the surface. Free-surface effects on the Peierls stress are investigated and compared with previous studies. An abnormal behavior of the Peierls stress of screw dislocations in a soft-inclusion film between two rigid films is predicted theoretically.

  20. Topological classification of the Goryachev integrable case in rigid body dynamics

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

    Nikolaenko, S S

    2016-01-31

    A topological analysis of the Goryachev integrable case in rigid body dynamics is made on the basis of the Fomenko-Zieschang theory. The invariants (marked molecules) which are obtained give a complete description, from the standpoint of Liouville classification, of the systems of Goryachev type on various level sets of the energy. It turns out that on appropriate energy levels the Goryachev case is Liouville equivalent to many classical integrable systems and, in particular, the Joukowski, Clebsch, Sokolov and Kovalevskaya-Yehia cases in rigid body dynamics, as well as to some integrable billiards in plane domains bounded by confocal quadrics -- in othermore » words, the foliations given by the closures of generic solutions of these systems have the same structure. Bibliography: 15 titles.« less

  1. Head-on collision of normal shock waves with rigid porous materials

    NASA Astrophysics Data System (ADS)

    Levy, A.; Ben-Dor, G.; Skews, B. W.; Sorek, S.

    1993-08-01

    The head-on collision of a planar shock wave with a rigid porous material has been investigated experimentally in a 75 mm × 75 mm shock tube. The experimental study indicated that unlike the reflection from a flexible porous material (e.g., polyurethane foam) where the transmitted compression waves do not converge to a sharp shock wave, in the case of a rigid porous material (e.g., alumina) the transmitted compression waves do converge to a sharp shock wave, which decays as it propagates along the porous material. In addition to this major difference, many other differences were observed. They are outlined in the following sections. Based on these observations a suggestion modifying the phenomenology of the reflection/interaction process in the case a porous material with large permeability is proposed.

  2. Nonlinear activity of acoustically driven gas bubble near a rigid boundary

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

    Maksimov, Alexey

    2015-10-28

    The presence of a boundary can produce considerable changes in the oscillation amplitude of the bubble and its scattered echo. The present study fills a gap in the literature, in that it is concerned theoretically with the bubble activity at relatively small distances from the rigid boundary. It was shown that the bi-spherical coordinates provide separation of variables and are more suitable for analysis of the dynamics of these constrained bubbles. Explicit formulas have been derived which describe the dependence of the bubble emission near a rigid wall on its size and the separation distance between the bubble and themore » boundary. As applications, time reversal technique for gas leakage detection and radiation forces that are induced by an acoustic wave on a constrained bubble were analyzed.« less

  3. Deformable registration for image-guided spine surgery: preserving rigid body vertebral morphology in free-form transformations

    NASA Astrophysics Data System (ADS)

    Reaungamornrat, S.; Wang, A. S.; Uneri, A.; Otake, Y.; Zhao, Z.; Khanna, A. J.; Siewerdsen, J. H.

    2014-03-01

    Purpose: Deformable registration of preoperative and intraoperative images facilitates accurate localization of target and critical anatomy in image-guided spine surgery. However, conventional deformable registration fails to preserve the morphology of rigid bone anatomy and can impart distortions that confound high-precision intervention. We propose a constrained registration method that preserves rigid morphology while allowing deformation of surrounding soft tissues. Method: The registration method aligns preoperative 3D CT to intraoperative cone-beam CT (CBCT) using free-form deformation (FFD) with penalties on rigid body motion imposed according to a simple intensity threshold. The penalties enforced 3 properties of a rigid transformation - namely, constraints on affinity (AC), orthogonality (OC), and properness (PC). The method also incorporated an injectivity constraint (IC) to preserve topology. Physical experiments (involving phantoms, an ovine spine, and a human cadaver) as well as digital simulations were performed to evaluate the sensitivity to registration parameters, preservation of rigid body morphology, and overall registration accuracy of constrained FFD in comparison to conventional unconstrained FFD (denoted uFFD) and Demons registration. Result: FFD with orthogonality and injectivity constraints (denoted FFD+OC+IC) demonstrated improved performance compared to uFFD and Demons. Affinity and properness constraints offered little or no additional improvement. The FFD+OC+IC method preserved rigid body morphology at near-ideal values of zero dilatation (D = 0.05, compared to 0.39 and 0.56 for uFFD and Demons, respectively) and shear (S = 0.08, compared to 0.36 and 0.44 for uFFD and Demons, respectively). Target registration error (TRE) was similarly improved for FFD+OC+IC (0.7 mm), compared to 1.4 and 1.8 mm for uFFD and Demons. Results were validated in human cadaver studies using CT and CBCT images, with FFD+OC+IC providing excellent preservation

  4. A rigid and thermally stable all ceramic optical support bench assembly for the LSST Camera

    NASA Astrophysics Data System (ADS)

    Kroedel, Matthias; Langton, J. Brian; Wahl, Bill

    2017-09-01

    This paper will present the ceramic design, fabrication and metrology results and assembly plan of the LSST camera optical bench structure which is using the unique manufacturing features of the HB-Cesic technology. The optical bench assembly consists of a rigid "Grid" fabrication supporting individual raft plates mounting sensor assemblies by way of a rigid kinematic support system to meet extreme stringent requirements for focal plane planarity and stability.

  5. Motion of a Rigid Body in a Special Lorentz Gas: Loss of Memory Effect

    NASA Astrophysics Data System (ADS)

    Koike, Kai

    2018-06-01

    Linear motion of a rigid body in a special kind of Lorentz gas is mathematically analyzed. The rigid body moves against gas drag according to Newton's equation. The gas model is a special Lorentz gas consisting of gas molecules and background obstacles, which was introduced in Tsuji and Aoki (J Stat Phys 146:620-645, 2012). The specular boundary condition is imposed on the resulting kinetic equation. This study complements the numerical study by Tsuji and Aoki cited above—although the setting in this paper is slightly different from theirs, qualitatively the same asymptotic behavior is proved: The velocity V(t) of the rigid body decays exponentially if the obstacles undergo thermal motion; if the obstacles are motionless, then the velocity V(t) decays algebraically with a rate t^{- 5} independent of the spatial dimension. This demonstrates the idea that interaction of the molecules with the background obstacles destroys the memory effect due to recollision.

  6. Introducing a Rigid Loop Structure from Deer into Mouse Prion Protein Increases Its Propensity for Misfolding In Vitro

    PubMed Central

    Kyle, Leah M.; John, Theodore R.; Schätzl, Hermann M.; Lewis, Randolph V.

    2013-01-01

    Prion diseases are fatal neurodegenerative disorders characterized by misfolding of the cellular prion protein (PrPc) into the disease-associated isoform (PrPSc) that has increased β-sheet content and partial resistance to proteolytic digestion. Prion diseases from different mammalian species have varying propensities for transmission upon exposure of an uninfected host to the infectious agent. Chronic Wasting Disease (CWD) is a highly transmissible prion disease that affects free ranging and farmed populations of cervids including deer, elk and moose, as well as other mammals in experimental settings. The molecular mechanisms allowing CWD to maintain comparatively high transmission rates have not been determined. Previous work has identified a unique structural feature in cervid PrP, a rigid loop between β-sheet 2 and α-helix 2 on the surface of the protein. This study was designed to test the hypothesis that the rigid loop has a direct influence on the misfolding process. The rigid loop was introduced into murine PrP as the result of two amino acid substitutions: S170N and N174T. Wild-type and rigid loop murine PrP were expressed in E. coli and purified. Misfolding propensity was compared for the two proteins using biochemical techniques and cell free misfolding and conversion systems. Murine PrP with a rigid loop misfolded in cell free systems with greater propensity than wild type murine PrP. In a lipid-based conversion assay, rigid loop PrP converted to a PK resistant, aggregated isoform at lower concentrations than wild-type PrP. Using both proteins as substrates in real time quaking-induced conversion, rigid loop PrP adopted a misfolded isoform more readily than wild type PrP. Taken together, these findings may help explain the high transmission rates observed for CWD within cervids. PMID:23825561

  7. Review of Intrathecal Baclofen Therapy for Spastic and Rigidity Disorders

    ERIC Educational Resources Information Center

    Obringer, S. John; Coffey, Kenneth M.

    2002-01-01

    Intrathecal baclofen therapy, a treatment for cerebral palsy and other spastic and rigidity disorders, is showing promise as an effective intervention. This article synthesizes both the medical and rehabilitation conceptual literature to update educators and related service providers as to the efficacy of this intervention. Implications for…

  8. How soft is that pillow? The perceptual localization of the hand and the haptic assessment of contact rigidity

    PubMed Central

    Pressman, Assaf; Karniel, Amir; Mussa-Ivaldi, Ferdinando A.

    2011-01-01

    A new haptic illusion is described, in which the location of the mobile object affects the perception of its rigidity. There is theoretical and experimental support to the notion that limb position sense results from the brain combining ongoing sensory information with expectations arising from prior experience. How does this probabilistic state information affect one’s tactile perception of the environment mechanics? In a simple estimation process human subjects were asked to report the relative rigidity of two simulated virtual objects. One of the objects remained fixed in space and had various coefficients of stiffness. The other virtual object had constant stiffness but moved with respect to the subjects. Earlier work suggested that the perception of an object’s rigidity is consistent with a process of regression between the contact force and the perceived amount of penetration inside the object’s boundary. The amount of penetration perceived by the subject was affected by varying the position of the object. This, in turn, had a predictable effect on the perceived rigidity of the contact. Subjects’ reports on the relative rigidity of the object are best accounted for by a probabilistic model in which the perceived boundary of the object is estimated based on its current location and on its past observations. Therefore, the perception of contact rigidity is accounted for by a stochastic process of state estimation underlying proprioceptive localization of the hand. PMID:21525300

  9. Performance of Cracked and Seated Rigid Airport Pavements.

    DTIC Science & Technology

    1987-04-01

    situ properties of the cracked PCC material and of the uncracked PCC. Additionally, a visual condition survey of the pavements under investigation was...the overall pavement evaluation effort. Results of the NDT testing program were used to determine the in-situ properties of the cracked PCC material ...combined with the NDT deflection basin slopes, led to the conclusion that the cracked and seated PCC layer is behaving as a semi-rigid material . 45 OVERLAY

  10. Plane stress problems using hysteretic rigid body spring network models

    NASA Astrophysics Data System (ADS)

    Christos, Sofianos D.; Vlasis, Koumousis K.

    2017-10-01

    In this work, a discrete numerical scheme is presented capable of modeling the hysteretic behavior of 2D structures. Rigid Body Spring Network (RBSN) models that were first proposed by Kawai (Nucl Eng Des 48(1):29-207, 1978) are extended to account for hysteretic elastoplastic behavior. Discretization is based on Voronoi tessellation, as proposed specifically for RBSN models to ensure uniformity. As a result, the structure is discretized into convex polygons that form the discrete rigid bodies of the model. These are connected with three zero length, i.e., single-node springs in the middle of their common facets. The springs follow the smooth hysteretic Bouc-Wen model which efficiently incorporates classical plasticity with no direct reference to a yield surface. Numerical results for both static and dynamic loadings are presented, which validate the proposed simplified spring-mass formulation. In addition, they verify the model's applicability on determining primarily the displacement field and plastic zones compared to the standard elastoplastic finite element method.

  11. Soft-rigid interaction mechanism towards a lobster-inspired hybrid actuator

    NASA Astrophysics Data System (ADS)

    Chen, Yaohui; Wan, Fang; Wu, Tong; Song, Chaoyang

    2018-01-01

    Soft pneumatic actuators (SPAs) are intrinsically light-weight, compliant and therefore ideal to directly interact with humans and be implemented into wearable robotic devices. However, they also pose new challenges in describing and sensing their continuous deformation. In this paper, we propose a hybrid actuator design with bio-inspirations from the lobsters, which can generate reconfigurable bending movements through the internal soft chamber interacting with the external rigid shells. This design with joint and link structures enables us to exactly track its bending configurations that previously posed a significant challenge to soft robots. Analytic models are developed to illustrate the soft-rigid interaction mechanism with experimental validation. A robotic glove using hybrid actuators to assist grasping is assembled to illustrate their potentials in safe human-robot interactions. Considering all the design merits, our work presents a practical approach to the design of next-generation robots capable of achieving both good accuracy and compliance.

  12. Influence of RNA Strand Rigidity on Polyion Complex Formation with Block Catiomers.

    PubMed

    Hayashi, Kotaro; Chaya, Hiroyuki; Fukushima, Shigeto; Watanabe, Sumiyo; Takemoto, Hiroyasu; Osada, Kensuke; Nishiyama, Nobuhiro; Miyata, Kanjiro; Kataoka, Kazunori

    2016-03-01

    Polyion complexes (b-PICs) are prepared by mixing single- or double-stranded oligo RNA (aniomer) with poly(ethylene glycol)-b-poly(L-lysine) (PEG-PLL) (block catiomer) to clarify the effect of aniomer chain rigidity on association behaviors at varying concentrations. Here, a 21-mer single-stranded RNA (ssRNA) (persistence length: 1.0 nm) and a 21-mer double-stranded RNA (small interfering RNA, siRNA) (persistence length: 62 nm) are compared. Both oligo RNAs form a minimal charge-neutralized ionomer pair with a single PEG-PLL chain, termed unit b-PIC (uPIC), at low concentrations (<≈ 0.01 mg mL(-1)). Above the critical association concentration (≈ 0.01 mg mL(-1)), ssRNA b-PICs form secondary associates, PIC micelles, with sizes up to 30-70 nm, while no such multimolecular assembly is observed for siRNA b-PICs. The entropy gain associated with the formation of a segregated PIC phase in the multimolecular PIC micelles may not be large enough for rigid siRNA strands to compensate with appreciably high steric repulsion derived from PEG chains. Chain rigidity appears to be a critical parameter in polyion complex association. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. RELATIONSHIP BETWEEN RIGIDITY OF EXTERNAL FIXATOR AND NUMBER OF PINS: COMPUTER ANALYSIS USING FINITE ELEMENTS

    PubMed Central

    Sternick, Marcelo Back; Dallacosta, Darlan; Bento, Daniela Águida; do Reis, Marcelo Lemos

    2015-01-01

    Objective: To analyze the rigidity of a platform-type external fixator assembly, according to different numbers of pins on each clamp. Methods: Computer simulation on a large-sized Cromus dynamic external fixator (Baumer SA) was performed using a finite element method, in accordance with the standard ASTM F1541. The models were generated with approximately 450,000 quadratic tetrahedral elements. Assemblies with two, three and four Schanz pins of 5.5 mm in diameter in each clamp were compared. Every model was subjected to a maximum force of 200 N, divided into 10 sub-steps. For the components, the behavior of the material was assumed to be linear, elastic, isotropic and homogeneous. For each model, the rigidity of the assembly and the Von Mises stress distribution were evaluated. Results: The rigidity of the system was 307.6 N/mm for two pins, 369.0 N/mm for three and 437.9 N/mm for four. Conclusion: The results showed that four Schanz pins in each clamp promoted rigidity that was 19% greater than in the configuration with three pins and 42% greater than with two pins. Higher tension occurred in configurations with fewer pins. In the models analyzed, the maximum tension occurred on the surface of the pin, close to the fixation area. PMID:27047879

  14. Prediction of air blast mitigation in an array of rigid obstacles using smoothed particle hydrodynamics

    NASA Astrophysics Data System (ADS)

    Prasanna Kumar, S. S.; Patnaik, B. S. V.; Ramamurthi, K.

    2018-04-01

    The mitigation of blast waves propagating in air and interacting with rigid barriers and obstacles is numerically investigated using the mesh-free smoothed particle hydrodynamics method. A novel virtual boundary particle procedure with a skewed gradient wall boundary treatment is applied at the interfaces between air and rigid bodies. This procedure is validated with closed-form solutions for strong and weak shock reflection from rigid surfaces, supersonic flows over a wedge, formation of reflected, transverse, and Mach stem shocks, and also earlier experiments on interaction of a blast wave with concrete blocks. The mitigation of the overpressure and impulse transmitted to the protected structure due to an array of rigid obstacles of different shapes placed in the path of the blast wave is thereafter determined and discussed in the context of the existing experimental and numerical studies. It is shown that blockages having the shape of a right facing triangle or square placed in tandem or staggered provide better mitigation. The influence of the distance between the blockage array and protected structure is assessed, and the incorporation of a gap in the blockages is shown to improve the mitigation. The mechanisms responsible for the attenuation of air blast are identified through the simulations.

  15. Development of mass production type rigid polyurethane foam for LNG carrier using ozone depletion free blowing agent

    NASA Astrophysics Data System (ADS)

    Lee, Yeongbeom; Baek, Kye Hyun; Choe, Kunhyung; Han, Chonghun

    2016-12-01

    Nowadays the price of natural gas has become higher and the efficiency of propulsion system of liquefied natural gas (LNG) carriers has improved. Due to these trends, required boil-off rate (BOR) for LNG carrier has been lowered from 0.15%/day to 0.12%/day for conventional LNG carriers with sizes between 125,000 m3 and 170,000 m3. This requirement of BOR can be satisfied by using a rigid polyurethane foam (PUF) blown by 1,1-dichloro-1-fluoroethane (HCFC-141b) as an insulator. However, ozone depletion potential (ODP) of HCFC-141b requires alternative blowing agents with zero ODP such as hydroflurocarbons (HFCs) because of tougher environmental regulations. This paper introduces use of HFCs and additives to enhance properties of rigid PUFs under a mass production environment. Among the additives, perfluoroalkane (PFA) reduces thermal conductivity down to 12% and increases compressive strength up to 15% of a rigid PUF prepared in a laboratory scale. Based on this result, a mass production type rigid PUF is manufactured and is evaluated for BOR, mechanical strengths over operation temperature range, and thermal shock stability for LNG carriers. The BOR of the manufactured rigid PUF is below 0.12%/day, which satisfies the recent BOR specification for LNG carriers. The other required properties are also met the specifications for a conventional LNG carrier. Consequently, it is expected that the results in this paper will bring low BOR (<0.12%/day) LNG carries with rigid PUFs using ODP free blowing agents and contribute environmental protection through saving energy and preserving the ozone layer in the stratosphere.

  16. Large-deflection theory for end compression of long rectangular plates rigidly clamped along two edges

    NASA Technical Reports Server (NTRS)

    Levy, Samuel; Krupen, Philip

    1943-01-01

    The von Karman equations for flat plates are solved beyond the buckling load up to edge strains equal to eight time the buckling strain, for the extreme case of rigid clamping along the edges parallel to the load. Deflections, bending stresses, and membrane stresses are given as a function of end compressive load. The theoretical values of effective width are compared with the values derived for simple support along the edges parallel to the load. The increases in effective width due to rigid clamping drops from about 20 percent near the buckling strain to about 8 percent at an edge strain equal to eight times the buckling strain. Experimental values of effective width in the elastic range reported in NACA Technical Note No. 684 are between the theoretical curves for the extremes of simple support and rigid clamping.

  17. Hierarchical and successive approximate registration of the non-rigid medical image based on thin-plate splines

    NASA Astrophysics Data System (ADS)

    Hu, Jinyan; Li, Li; Yang, Yunfeng

    2017-06-01

    The hierarchical and successive approximate registration method of non-rigid medical image based on the thin-plate splines is proposed in the paper. There are two major novelties in the proposed method. First, the hierarchical registration based on Wavelet transform is used. The approximate image of Wavelet transform is selected as the registered object. Second, the successive approximation registration method is used to accomplish the non-rigid medical images registration, i.e. the local regions of the couple images are registered roughly based on the thin-plate splines, then, the current rough registration result is selected as the object to be registered in the following registration procedure. Experiments show that the proposed method is effective in the registration process of the non-rigid medical images.

  18. 21 CFR 874.4710 - Esophagoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... disease, or to remove foreign bodies from the esophagus. When inserted, the device extends from the area.... 874.4710 Section 874.4710 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... generic type of device includes the flexible foreign body claw, flexible biopsy forceps, rigid biopsy...

  19. 21 CFR 874.4710 - Esophagoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... disease, or to remove foreign bodies from the esophagus. When inserted, the device extends from the area.... 874.4710 Section 874.4710 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... generic type of device includes the flexible foreign body claw, flexible biopsy forceps, rigid biopsy...

  20. 21 CFR 874.4710 - Esophagoscope (flexible or rigid) and accessories.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... disease, or to remove foreign bodies from the esophagus. When inserted, the device extends from the area.... 874.4710 Section 874.4710 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... generic type of device includes the flexible foreign body claw, flexible biopsy forceps, rigid biopsy...

  1. Enhanced enzyme kinetic stability by increasing rigidity within the active site.

    PubMed

    Xie, Yuan; An, Jiao; Yang, Guangyu; Wu, Geng; Zhang, Yong; Cui, Li; Feng, Yan

    2014-03-14

    Enzyme stability is an important issue for protein engineers. Understanding how rigidity in the active site affects protein kinetic stability will provide new insight into enzyme stabilization. In this study, we demonstrated enhanced kinetic stability of Candida antarctica lipase B (CalB) by mutating the structurally flexible residues within the active site. Six residues within 10 Å of the catalytic Ser(105) residue with a high B factor were selected for iterative saturation mutagenesis. After screening 2200 colonies, we obtained the D223G/L278M mutant, which exhibited a 13-fold increase in half-life at 48 °C and a 12 °C higher T50(15), the temperature at which enzyme activity is reduced to 50% after a 15-min heat treatment. Further characterization showed that global unfolding resistance against both thermal and chemical denaturation also improved. Analysis of the crystal structures of wild-type CalB and the D223G/L278M mutant revealed that the latter formed an extra main chain hydrogen bond network with seven structurally coupled residues within the flexible α10 helix that are primarily involved in forming the active site. Further investigation of the relative B factor profile and molecular dynamics simulation confirmed that the enhanced rigidity decreased fluctuation of the active site residues at high temperature. These results indicate that enhancing the rigidity of the flexible segment within the active site may provide an efficient method for improving enzyme kinetic stability.

  2. CONTROL TECHNOLOGY OVERVIEW REPORT: CFC (CHLOROFLUOROCARBON) EMISSIONS FROM RIGID FOAM MANUFACTURING

    EPA Science Inventory

    The report estimates total chlorofluorocarbon (CFC) emissions from the various rigid foam manufacturing processes and from the foam products themselves, and examines potential methods for reducing these emissions. Options studied include replacement of CFC-blown products with alt...

  3. Sterility maintenance study: Dynamic evaluation of sterilized rigid containers and wrapped instrument trays to prevent bacterial ingress.

    PubMed

    Shaffer, Harry L; Harnish, Delbert A; McDonald, Michael; Vernon, Reid A; Heimbuch, Brian K

    2015-12-01

    Sterilized packaging systems are designed to maintain the sterility of surgical instruments and devices from the time of sterilization until use. This study evaluated the effectiveness of rigid containers versus wrapped instrument trays, sterilized using North American sterilization protocols, to maintain a sterile internal environment poststerilization when challenged with aerosolized bacteria under dynamic environmental conditions. Using a custom aerosol chamber, 111 rigid containers of various durations of use (unused, used <5 years, used 5-9 years) and 161 wrapped trays using 3 grades of sterilization wrap were challenged with ~10(2) colony-forming units per liter of air containing aerosolized Micrococcus luteus with a count median particle size of 1 μm, while simultaneously experiencing air volume exchanges due to vacuum cycles-two 1-psi cycles, three 0.7-psi cycles, and three 0.4-psi cycles-to simulate air exchange events occurring during the sterilization, transportation, and storage of sterilized instrument trays in health care facilities. Of 111 rigid containers tested, 97 (87%) demonstrated bacterial ingress into the container. Of 161 wrapped trays, 0 (0%) demonstrated bacterial ingress into the tray. Contamination rates of rigid containers increased significantly with increasing duration of use. In this study using a dynamic bacterial aerosol challenge, sterilized wrapped trays demonstrated significantly greater protection than sterilized rigid containers against the ingress of airborne bacteria. Copyright © 2015. Published by Elsevier Inc.

  4. Experimental analysis of internal rigid fixation osteosynthesis performed with titanium bone screw and plate systems.

    PubMed

    Righi, E; Carta, M; Bruzzone, A A; Lonardo, P M; Marinaro, E; Pastorino, A

    1996-02-01

    The authors report the results of an experimental analysis performed on titanium miniplates and screws in order to gain a better understanding of dynamic forces in internal rigid fixation. Ten segments of bovine scapula were prepared. Osteotomies were carried out along the minor axis, following which five were fixed with four hole straight miniplates and the other five with six hole double-Y miniplates. Each sample was fastened in a special clamp adapted to a tension test machine and shearing force was applied. Force versus time was recorded and the 50 bone fragments were examined by a pathologist. On the basis of the test results, two simple computer models were developed. No significant difference was evident between the mechanical and computed tests. The most critical sections were located near the hole proximal to the osteotomy and the microscopic findings confirmed this. On the basis of the experimental results, the authors propose a new plate design in which the area subject to most stress, proximal to the bone section, would be of miniplate thickness, the distal aspect being thinner as in a microplate. It is suggested that this design would provide sufficient stability and a high degree of anatomical adjustment of the system.

  5. Role of sufficient phosphorus in biodiesel production from diatom Phaeodactylum tricornutum.

    PubMed

    Yu, Shi-Jin; Shen, Xiao-Fei; Ge, Huo-Qing; Zheng, Hang; Chu, Fei-Fei; Hu, Hao; Zeng, Raymond J

    2016-08-01

    In order to study the role of sufficient phosphorus (P) in biodiesel production by microalgae, Phaeodactylum tricornutum were cultivated in six different media treatments with combination of nitrogen (N) sufficiency/deprivation and phosphorus sufficiency/limitation/deprivation. Profiles of N and P, biomass, and fatty acids (FAs) content and compositions were measured during a 7-day cultivation period. The results showed that the FA content in microalgae biomass was promoted by P deprivation. However, statistical analysis showed that FA productivity had no significant difference (p = 0.63, >0.05) under the treatments of N deprivation with P sufficiency (N-P) and N deprivation with P deprivation (N-P-), indicating P sufficiency in N deprivation medium has little effect on increasing biodiesel productivity from P. triornutum. It was also found that the P absorption in N-P medium was 1.41 times higher than that in N sufficiency and P sufficiency (NP) medium. N deprivation with P limitation (N-P-l) was the optimal treatment for producing biodiesel from P. triornutum because of both the highest FA productivity and good biodiesel quality.

  6. Coherent distributions for the rigid rotator

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

    Grigorescu, Marius

    2016-06-15

    Coherent solutions of the classical Liouville equation for the rigid rotator are presented as positive phase-space distributions localized on the Lagrangian submanifolds of Hamilton-Jacobi theory. These solutions become Wigner-type quasiprobability distributions by a formal discretization of the left-invariant vector fields from their Fourier transform in angular momentum. The results are consistent with the usual quantization of the anisotropic rotator, but the expected value of the Hamiltonian contains a finite “zero point” energy term. It is shown that during the time when a quasiprobability distribution evolves according to the Liouville equation, the related quantum wave function should satisfy the time-dependent Schrödingermore » equation.« less

  7. Absence of bacterial colonization of the airways after therapeutic rigid bronchoscopy without stenting.

    PubMed

    Noppen, M; Piérard, D; Meysman, M; Herreweghe, R V; Vincken, W

    2000-12-01

    Following airway stenting, bacterial colonization of the airways with potentially pathogenic micro-organisms occurs within 4 weeks after treatment in the majority of patients. The objective of this study was to prospectively investigate whether nonstenting therapeutic rigid bronchoscopy (using laser, cryotherapy, mechanical dilatation or debridement) is followed by airway colonization or infection. Protected specimen brush sampling of the central airways and quantitative culture were performed immediately prior to, and 4 weeks after nonstenting therapeutic rigid bronchoscopy in 20 consecutive patients with central airway lesions. Prior to therapeutic bronchoscopy, airway colonization/infection was present in nine of 20 (45%) patients. In these nine patients, 10 different potential pathogens were identified: Streptococcus pneumoniae (four cases), Pseudomonas aeruginosa (three), Haemophilus influenzae (two), and Serratia marcescens (one). Eight of these nine patients had a history of postobstructive infections, of which three were currently being treated with antibiotics. Four weeks following therapeutic bronchoscopy, airway colonization/infection was present in five of 20 (25%) patients, each of whom had airway colonization/infection prior to bronchoscopy. In three of these five patients, the same organisms were found 4 weeks after bronchoscopy as at baseline bronchoscopy. In two of five patients new organisms were identified: one case of Streptococcus viridans and one case of Haemophilus parainfluenzae, both considered to be nonpathogens. In four of nine patients with airway colonization/infection prior to bronchoscopy, the airways were clear of micro-organisms after the procedure. The authors conclude that: 1) nonstenting therapeutic rigid bronchoscopy is not complicated by airway colonization or infection by new potential pathogens; and 2) therapeutic rigid bronchoscopy led to clearing of airway colonization/infection in almost half of the patients studied.

  8. Minimal sufficient positive-operator valued measure on a separable Hilbert space

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

    Kuramochi, Yui, E-mail: kuramochi.yui.22c@st.kyoto-u.ac.jp

    We introduce a concept of a minimal sufficient positive-operator valued measure (POVM), which is the least redundant POVM among the POVMs that have the equivalent information about the measured quantum system. Assuming the system Hilbert space to be separable, we show that for a given POVM, a sufficient statistic called a Lehmann-Scheffé-Bahadur statistic induces a minimal sufficient POVM. We also show that every POVM has an equivalent minimal sufficient POVM and that such a minimal sufficient POVM is unique up to relabeling neglecting null sets. We apply these results to discrete POVMs and information conservation conditions proposed by the author.

  9. High temperature electrical conductivity of rigid polyurethane foam

    NASA Astrophysics Data System (ADS)

    Johnson, R. T., Jr.

    1984-03-01

    The temperature dependence of the electrical conductivity of three rigid polyurethane foams prepared using different formulations was measured to approx. 320 C. The materials exhibit similar conductivity characteristics, showing a pronounced increase in conductivity with increasing temperature. The insulating characteristics to approx. 200 C are better than that for phenolic materials (glass fabric reinforced), and are similar to those for silicone materials (glass microsphere reinforced). At higher temperatures (500 to 600 C), the phenolics and silicones are better insulators.

  10. Gas-induced friction and diffusion of rigid rotors

    NASA Astrophysics Data System (ADS)

    Martinetz, Lukas; Hornberger, Klaus; Stickler, Benjamin A.

    2018-05-01

    We derive the Boltzmann equation for the rotranslational dynamics of an arbitrary convex rigid body in a rarefied gas. It yields as a limiting case the Fokker-Planck equation accounting for friction, diffusion, and nonconservative drift forces and torques. We provide the rotranslational friction and diffusion tensors for specular and diffuse reflection off particles with spherical, cylindrical, and cuboidal shape, and show that the theory describes thermalization, photophoresis, and the inverse Magnus effect in the free molecular regime.

  11. Oscillations of manometric tubular springs with rigid end

    NASA Astrophysics Data System (ADS)

    Cherentsov, D. A.; Pirogov, S. P.; Dorofeev, S. M.; Ryabova, Y. S.

    2018-05-01

    The paper presents a mathematical model of attenuating oscillations of manometric tubular springs (MTS) taking into account the rigid tip. The dynamic MTS model is presented in the form of a thin-walled curved rod oscillating in the plane of curvature of the central axis. Equations for MTS oscillations are obtained in accordance with the d’Alembert principle in projections onto the normal and tangential. The Bubnov-Galerkin method is used to solve the equations obtained.

  12. A new pre-loaded beam geometric stiffness matrix with full rigid body capabilities

    NASA Astrophysics Data System (ADS)

    Bosela, P. A.; Fertis, D. G.; Shaker, F. J.

    1992-09-01

    Space structures, such as the Space Station solar arrays, must be extremely light-weight, flexible structures. Accurate prediction of the natural frequencies and mode shapes is essential for determining the structural adequacy of components, and designing a controls system. The tension pre-load in the 'blanket' of photovoltaic solar collectors, and the free/free boundary conditions of a structure in space, causes serious reservations on the use of standard finite element techniques of solution. In particular, a phenomenon known as 'grounding', or false stiffening, of the stiffness matrix occurs during rigid body rotation. The authors have previously shown that the grounding phenomenon is caused by a lack of rigid body rotational capability, and is typical in beam geometric stiffness matrices formulated by others, including those which contain higher order effects. The cause of the problem was identified as the force imbalance inherent in the formulations. In this paper, the authors develop a beam geometric stiffness matrix for a directed force problem, and show that the resultant global stiffness matrix contains complete rigid body mode capabilities, and performs very well in the diagonalization methodology customarily used in dynamic analysis.

  13. 49 CFR 178.925 - Standards for rigid plastic Large Packagings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... manufacture of the tested design type, retesting may be omitted if changes in the carbon black content, the... or chemical properties of the material of construction. (3) No used material other than production residues or regrind from the same manufacturing process may be used in the manufacture of rigid plastic...

  14. Cosmic ray intensity variations at primary rigidities near 1900 GV

    NASA Technical Reports Server (NTRS)

    Lee, Y. W.; Mackeown, P. K.; Ng, L. K.

    1985-01-01

    Preliminary analysis of an experiment monitoring cosmic ray muons yields a first sidereal harmonic amplitude for rigidities around 1900 GV of (7.95 + or - 3.97) 10 to the 0.001 power at 5.1 + or - 1.9h right ascention. A significant anti-sidereal first harmonic is, however, also seen.

  15. Graph rigidity, cyclic belief propagation, and point pattern matching.

    PubMed

    McAuley, Julian J; Caetano, Tibério S; Barbosa, Marconi S

    2008-11-01

    A recent paper [1] proposed a provably optimal polynomial time method for performing near-isometric point pattern matching by means of exact probabilistic inference in a chordal graphical model. Its fundamental result is that the chordal graph in question is shown to be globally rigid, implying that exact inference provides the same matching solution as exact inference in a complete graphical model. This implies that the algorithm is optimal when there is no noise in the point patterns. In this paper, we present a new graph that is also globally rigid but has an advantage over the graph proposed in [1]: Its maximal clique size is smaller, rendering inference significantly more efficient. However, this graph is not chordal, and thus, standard Junction Tree algorithms cannot be directly applied. Nevertheless, we show that loopy belief propagation in such a graph converges to the optimal solution. This allows us to retain the optimality guarantee in the noiseless case, while substantially reducing both memory requirements and processing time. Our experimental results show that the accuracy of the proposed solution is indistinguishable from that in [1] when there is noise in the point patterns.

  16. Rigid spherical particles in highly turbulent Taylor-Couette flow

    NASA Astrophysics Data System (ADS)

    Bakhuis, Dennis; Verschoof, Ruben A.; Mathai, Varghese; Huisman, Sander G.; Lohse, Detlef; Sun, Chao

    2016-11-01

    Many industrial and maritime processes are subject to enormous frictional losses. Reducing these losses even slightly will already lead to large financial and environmental benefits. The understanding of the underlying physical mechanism of frictional drag reduction is still limited, for example, in bubbly drag reduction there is an ongoing debate whether deformability and bubble size are the key parameters. In this experimental study we report high precision torque measurements using rigid non-deformable spherical particles in highly turbulent Taylor-Couette flow with Reynolds numbers up to 2 ×106 . The particles are made of polystyrene with an average density of 1.036 g cm-3 and three different diameters: 8mm, 4mm, and 1.5mm. Particle volume fractions of up to 6% were used. By varying the particle diameter, density ratio of the particles and the working fluid, and volume fraction of the particles, the effect on the torque is compared to the single phase case. These systematic measurements show that adding rigid spherical particles only results in very minor drag reduction. This work is financially supported by Netherlands Organisation for Scientific Research (NWO) by VIDI Grant Number 13477.

  17. A numerical method for simulations of rigid fiber suspensions

    NASA Astrophysics Data System (ADS)

    Tornberg, Anna-Karin; Gustavsson, Katarina

    2006-06-01

    In this paper, we present a numerical method designed to simulate the challenging problem of the dynamics of slender fibers immersed in an incompressible fluid. Specifically, we consider microscopic, rigid fibers, that sediment due to gravity. Such fibers make up the micro-structure of many suspensions for which the macroscopic dynamics are not well understood. Our numerical algorithm is based on a non-local slender body approximation that yields a system of coupled integral equations, relating the forces exerted on the fibers to their velocities, which takes into account the hydrodynamic interactions of the fluid and the fibers. The system is closed by imposing the constraints of rigid body motions. The fact that the fibers are straight have been further exploited in the design of the numerical method, expanding the force on Legendre polynomials to take advantage of the specific mathematical structure of a finite-part integral operator, as well as introducing analytical quadrature in a manner possible only for straight fibers. We have carefully treated issues of accuracy, and present convergence results for all numerical parameters before we finally discuss the results from simulations including a larger number of fibers.

  18. Normalized inverse characterization of sound absorbing rigid porous media.

    PubMed

    Zieliński, Tomasz G

    2015-06-01

    This paper presents a methodology for the inverse characterization of sound absorbing rigid porous media, based on standard measurements of the surface acoustic impedance of a porous sample. The model parameters need to be normalized to have a robust identification procedure which fits the model-predicted impedance curves with the measured ones. Such a normalization provides a substitute set of dimensionless (normalized) parameters unambiguously related to the original model parameters. Moreover, two scaling frequencies are introduced, however, they are not additional parameters and for different, yet reasonable, assumptions of their values, the identification procedure should eventually lead to the same solution. The proposed identification technique uses measured and computed impedance curves for a porous sample not only in the standard configuration, that is, set to the rigid termination piston in an impedance tube, but also with air gaps of known thicknesses between the sample and the piston. Therefore, all necessary analytical formulas for sound propagation in double-layered media are provided. The methodology is illustrated by one numerical test and by two examples based on the experimental measurements of the acoustic impedance and absorption of porous ceramic samples of different thicknesses and a sample of polyurethane foam.

  19. Photophysical properties and photoisomerization processes of Methyl Red embedded in rigid polymer

    NASA Astrophysics Data System (ADS)

    Lee, Geon Joon; Kim, Dongho; Lee, Minyung

    1995-01-01

    The photophysical properties of Methyl Red molecules embedded in a poly(methyl methacrylate) (PMMA) matrix were investigated with photoinduced absorption, absorption kinetics, steady-state, and time-resolved luminescence spectroscopy. The excited singlet (S1) state lifetimes for trans and cis isomers of Methyl Red in PMMA at room temperature have been measured as 35 and 420 ps, respectively. The excited triplet (T1) state energy level and its lifetime at 77 K were also obtained. A slow trans-cis isomerization process having a time constant of a few hundred seconds was observed for the illuminated Methyl Red in rigid polymer. Based on measured photophysical properties and dynamic processes, an energy-level diagram for Methyl Red molecules in rigid polymer is introduced to explain these observations.

  20. Crack Initiation and Growth in Rigid Polymeric Closed-Cell Foam Cryogenic Applications

    NASA Technical Reports Server (NTRS)

    Sayyah, Tarek; Steeve, Brian; Wells, Doug

    2006-01-01

    Cryogenic vessels, such as the Space Shuttle External Tank, are often insulated with closed-cell foam because of its low thermal conductivity. The coefficient of thermal expansion mismatch between the foam and metallic substrate places the foam under a biaxial tension gradient through the foam thickness. The total foam thickness affects the slope of the stress gradient and is considered a significant contributor to the initiation of subsurface cracks. Rigid polymeric foams are brittle in nature and any subsurface cracks tend to propagate a finite distance toward the surface. This presentation investigates the relationship between foam thickness and crack initiation and subsequent crack growth, using linear elastic fracture mechanics, in a rigid polymeric closed-cell foam through analysis and comparison with experimental results.

  1. Effects of Perforation on Rigid PU Foam Plates: Acoustic and Mechanical Properties.

    PubMed

    Lin, Jia-Horng; Chuang, Yu-Chun; Li, Ting-Ting; Huang, Chen-Hung; Huang, Chien-Lin; Chen, Yueh-Sheng; Lou, Ching-Wen

    2016-12-09

    Factories today are equipped with diverse mechanical equipment in response to rapid technological and industrial developments. Industrial areas located near residential neighborhoods cause massive environmental problems. In particular, noise pollution results in physical and psychological discomfort, and is a seen as invisible and inevitable problem. Thus, noise reduction is a critical and urgent matter. In this study, rigid polyurethane (PU) foam plates undergo perforation using a tapping machine. The mechanical and acoustic properties of these perforated plates as related to perforation rate and perforation depth are evaluated in terms of compression strength, drop-weight impact strength, and sound absorption coefficient. Experimental results indicate that applying the perforation process endows the rigid PU foaming plates with greater load absorption and better sound absorption at medium and high frequencies.

  2. Application of the integral manifold method to the analysis of the spatial motion of a rigid body fixed to a cable

    NASA Astrophysics Data System (ADS)

    Zabolotnov, Yu. M.

    2016-07-01

    We analyze the spatial motion of a rigid body fixed to a cable about its center of mass when the orbital cable system is unrolling. The analysis is based on the integral manifold method, which permits separating the rigid body motion into the slow and fast components. The motion of the rigid body is studied in the case of slow variations in the cable tension force and under the action of various disturbances.We estimate the influence of the static and dynamic asymmetry of the rigid body on its spatial motion about the cable fixation point. An example of the analysis of the rigid body motion when the orbital cable system is unrolling is given for a special program of variations in the cable tension force. The conditions of applicability of the integral manifold method are analyzed.

  3. How do heterogeneities in single cell rigidity influence the mechanical behavior at the tissue level?

    NASA Astrophysics Data System (ADS)

    Bi, Dapeng; Wetzel, Franziska; Fritsch, Anatol; Marchetti, M. Cristina; Manning, M. Lisa; Kaes, Josef

    It has been long recognized that solid tumor tissues are mechanically more rigid than surrounding healthy tissues. However recent experiments have shown that in primary tumor samples from patients with mammary and cervix carcinomas, cells exhibit a broad distribution of rigidities, with a higher fraction of softer and more contractile cells compared to normal tissues. This gives rise to a paradox: does softness emerge from adaptation to mechanical and chemical cues in the external microenvironment, or are soft cells already present inside a primary solid tumor? Motivated by these observations, we study a model of dense tissues that incorporates the experimental data for cell stiffness variations to reveal that, surprisingly, tumors with a significant fraction of very soft cells can still remain rigid. Moreover, in tissues with the observed distributions of cell stiffnesses, softer cells spontaneously self-organize into lines or streams, possibly facilitating cancer metastasis.

  4. SU-G-BRA-14: Dose in a Rigidly Moving Phantom with Jaw and MLC Compensation

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

    Chao, E; Lucas, D

    Purpose: To validate dose calculation for a rigidly moving object with jaw motion and MLC shifts to compensate for the motion in a TomoTherapy™ treatment delivery. Methods: An off-line version of the TomoTherapy dose calculator was extended to perform dose calculations for rigidly moving objects. A variety of motion traces were added to treatment delivery plans, along with corresponding jaw compensation and MLC shift compensation profiles. Jaw compensation profiles were calculated by shifting the jaws such that the center of the treatment beam moved by an amount equal to the motion in the longitudinal direction. Similarly, MLC compensation profiles weremore » calculated by shifting the MLC leaves by an amount that most closely matched the motion in the transverse direction. The same jaw and MLC compensation profiles were used during simulated treatment deliveries on a TomoTherapy system, and film measurements were obtained in a rigidly moving phantom. Results: The off-line TomoTherapy dose calculator accurately predicted dose profiles for a rigidly moving phantom along with jaw motion and MLC shifts to compensate for the motion. Calculations matched film measurements to within 2%/1 mm. Jaw and MLC compensation substantially reduced the discrepancy between the delivered dose distribution and the calculated dose with no motion. For axial motion, the compensated dose matched the no-motion dose within 2%/1mm. For transverse motion, the dose matched within 2%/3mm (approximately half the width of an MLC leaf). Conclusion: The off-line TomoTherapy dose calculator accurately computes dose delivered to a rigidly moving object, and accurately models the impact of moving the jaws and shifting the MLC leaf patterns to compensate for the motion. Jaw tracking and MLC leaf shifting can effectively compensate for the dosimetric impact of motion during a TomoTherapy treatment delivery.« less

  5. The management of amputations of the leg using a new rigid foam plaster for prosthetic fitting.

    PubMed

    Hölter, W; Echterhoff, M; Blömer, A; Verfürden, H

    1980-01-01

    This paper describes the use of a rigid polyurethane foam to construct a stump socket for immediate or early prosthetic fitting in 15 patients with amputation through the leg. The foam plaster is poured into a prepared cotton sleeve, with a zip incorporated, and rolled out to a layer 4 mm thick. The filled sleeve is put around the stump and the zip closed, moulding the sleeve firmly to the stump. The closed sleeve hardens into a rigid polyurethane shell within 20 min. Aferwards the skeletal prosthetic components are fixed with the same rigid foam. The polyurethane foam socket is quickly and cleanly prepared, only one third of the weight of a plaster of Paris cast and is easily removed by means of the zip, allowing access to the stump.

  6. Effects of dielectric inhomogeneity on electrostatic twist rigidity of a helical biomolecule in Debye-Hückel regime

    NASA Astrophysics Data System (ADS)

    Rezaie-Dereshgi, Amir; Mohammad-Rafiee, Farshid

    2018-04-01

    The electrostatic interactions play a crucial role in biological systems. Here we consider an impermeable dielectric molecule in the solvent with a different dielectric constant. The electrostatic free energy in the problem is studied in the Debye-Hückel regime using the analytical Green function that is calculated in the paper. Using this electrostatic free energy, we study the electrostatic contribution to the twist rigidity of a double stranded helical molecule such as a DNA and an actin filament. The dependence of the electrostatic twist rigidity of the molecule to the dielectric inhomogeneity, structural parameters, and the salt concentration is studied. It is shown that, depending on the parameters, the electrostatic twist rigidity could be positive or negative.

  7. The relation between disparity and velocity signals of rigidly moving objects constrains depth order perception.

    PubMed

    Di Luca, Massimiliano; Domini, Fulvio; Caudek, Corrado

    2007-05-01

    In two experiments, observers were asked to judge the relative depth of a probe and one or two flanker dots. In Experiment 1, we found that such judgments were influenced by the properties of adjacent image regions, that is, by the amount of angular rotation of a surrounding cloud of dots. In Experiment 2, we found that the properties of the adjacent image regions affected the precision of the observers' judgments. With only the probe and the flanker dots presented in isolation, the precision of observers' judgments was much lower than when probe and the flanker dots were surrounded by a rigidly-connected cloud of dots. Conversely, a non-rigid rotation of the surrounding dots was detrimental to the precision of visual performance. These data can be accounted for by the Intrinsic Constraint model [Domini, F., Caudek, C., & Tassinari, H. (2006). Stereo and motion information are not independently processed by the visual system. Vision Research, 46, 1707-1723], which incorporates the mutual constraints relating disparity and motion signals. The present investigation does not show that the rigidity constraint affects the visual interpretation of motion information alone. Rather, our results show that perceptual performance is affected by the linear relation between disparity and velocity signals, when both depth-cues are present and the distal object is, in fact, rigid.

  8. Accurate free and forced rotational motions of rigid Venus

    NASA Astrophysics Data System (ADS)

    Cottereau, L.; Souchay, J.; Aljbaae, S.

    2010-06-01

    Context. The precise and accurate modelling of a terrestrial planet like Venus is an exciting and challenging topic, all the more interesting because it can be compared with that of Earth for which such a modelling has already been achieved at the milli-arcsecond level. Aims: We aim to complete a previous study, by determining the polhody at the milli-arcsecond level, i.e. the torque-free motion of the angular momentum axis of a rigid Venus in a body-fixed frame, as well as the nutation of its third axis of figure in space, which is fundamental from an observational point of view. Methods: We use the same theoretical framework as Kinoshita (1977, Celest. Mech., 15, 277) did to determine the precession-nutation motion of a rigid Earth. It is based on a representation of the rotation of a rigid Venus, with the help of Andoyer variables and a set of canonical equations in Hamiltonian formalism. Results: In a first part we computed the polhody, we showed that this motion is highly elliptical, with a very long period of 525 cy compared with 430 d for the Earth. This is due to the very small dynamical flattening of Venus in comparison with our planet. In a second part we precisely computed the Oppolzer terms, which allow us to represent the motion in space of the third Venus figure axis with respect to the Venus angular momentum axis under the influence of the solar gravitational torque. We determined the corresponding tables of the nutation coefficients of the third figure axis both in longitude and in obliquity due to the Sun, which are of the same order of amplitude as for the Earth. We showed that the nutation coefficients for the third figure axis are significantly different from those of the angular momentum axis on the contrary of the Earth. Our analytical results have been validated by a numerical integration, which revealed the indirect planetary effects.

  9. Rigidity of complete generic shrinking Ricci solitons

    NASA Astrophysics Data System (ADS)

    Chu, Yawei; Zhou, Jundong; Wang, Xue

    2018-01-01

    Let (Mn , g , X) be a complete generic shrinking Ricci soliton of dimension n ≥ 3. In this paper, by employing curvature inequalities, the formula of X-Laplacian for the norm square of the trace-free curvature tensor, the weak maximum principle and the estimate of the scalar curvature of (Mn , g) , we prove some rigidity results for (Mn , g , X) . In particular, it is showed that (Mn , g , X) is isometric to Rn or a finite quotient of Sn under a pointwise pinching condition. Moreover, we establish several optimal inequalities and classify those shrinking solitons for equalities.

  10. A soft-rigid contact model of MPM for granular flow impact on retaining structures

    NASA Astrophysics Data System (ADS)

    Li, Xinpo; Xie, Yanfang; Gutierrez, Marte

    2018-02-01

    Protective measures against hazards associated with rapid debris avalanches include a variety of retaining structures such as rock/boulder fences, gabions, earthfill barriers and retaining walls. However, the development of analytical and numerical methods for the rational assessment of impact force generated by granular flows is still a challenge. In this work, a soft-rigid contact model is built under the coding framework of MPM which is a hybrid method with Eulerian-Lagrangian description. The soft bodies are discretized into particles (material points), and the rigid bodies are presented by rigid node-based surfaces. Coulomb friction model is used to implement the modeled contact mechanics, and a velocity-dependent friction coefficient is coupled into the model. Simulations of a physical experiment show that the peak and residual value of impact forces are well captured by the MPM model. An idealized scenario of debris avalanche flow down a hillslope and impacting on a retaining wall are analyzed using the MPM model. The calculated forces can provide a quantitative estimate from which mound design could proceed for practical implementation in the field.

  11. Robust group-wise rigid registration of point sets using t-mixture model

    NASA Astrophysics Data System (ADS)

    Ravikumar, Nishant; Gooya, Ali; Frangi, Alejandro F.; Taylor, Zeike A.

    2016-03-01

    A probabilistic framework for robust, group-wise rigid alignment of point-sets using a mixture of Students t-distribution especially when the point sets are of varying lengths, are corrupted by an unknown degree of outliers or in the presence of missing data. Medical images (in particular magnetic resonance (MR) images), their segmentations and consequently point-sets generated from these are highly susceptible to corruption by outliers. This poses a problem for robust correspondence estimation and accurate alignment of shapes, necessary for training statistical shape models (SSMs). To address these issues, this study proposes to use a t-mixture model (TMM), to approximate the underlying joint probability density of a group of similar shapes and align them to a common reference frame. The heavy-tailed nature of t-distributions provides a more robust registration framework in comparison to state of the art algorithms. Significant reduction in alignment errors is achieved in the presence of outliers, using the proposed TMM-based group-wise rigid registration method, in comparison to its Gaussian mixture model (GMM) counterparts. The proposed TMM-framework is compared with a group-wise variant of the well-known Coherent Point Drift (CPD) algorithm and two other group-wise methods using GMMs, using both synthetic and real data sets. Rigid alignment errors for groups of shapes are quantified using the Hausdorff distance (HD) and quadratic surface distance (QSD) metrics.

  12. Vision-based stress estimation model for steel frame structures with rigid links

    NASA Astrophysics Data System (ADS)

    Park, Hyo Seon; Park, Jun Su; Oh, Byung Kwan

    2017-07-01

    This paper presents a stress estimation model for the safety evaluation of steel frame structures with rigid links using a vision-based monitoring system. In this model, the deformed shape of a structure under external loads is estimated via displacements measured by a motion capture system (MCS), which is a non-contact displacement measurement device. During the estimation of the deformed shape, the effective lengths of the rigid link ranges in the frame structure are identified. The radius of the curvature of the structural member to be monitored is calculated using the estimated deformed shape and is employed to estimate stress. Using MCS in the presented model, the safety of a structure can be assessed gauge-freely. In addition, because the stress is directly extracted from the radius of the curvature obtained from the measured deformed shape, information on the loadings and boundary conditions of the structure are not required. Furthermore, the model, which includes the identification of the effective lengths of the rigid links, can consider the influences of the stiffness of the connection and support on the deformation in the stress estimation. To verify the applicability of the presented model, static loading tests for a steel frame specimen were conducted. By comparing the stress estimated by the model with the measured stress, the validity of the model was confirmed.

  13. Noncovalent Interactions in the Asymmetric Synthesis of Rigid, Conjugated Helical Structures

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

    Miyasaka, Makoto; Pink, Maren; Rajca, Suchada

    Tetrakis({beta}-trithiophene) 1 folds into a helical conformation (RRR) that facilitates double ring annelation, with high diastereoselectivity and modest enantioselectivity, to provide bis[7]helicene 2 (MRM). This rigid, helically locked structure has enhanced chiroptical properties similar to the corresponding [15]helicene.

  14. Pink frilly dresses and the avoidance of all things "girly": children's appearance rigidity and cognitive theories of gender development.

    PubMed

    Halim, May Ling; Ruble, Diane N; Tamis-LeMonda, Catherine S; Zosuls, Kristina M; Lurye, Leah E; Greulich, Faith K

    2014-04-01

    Many young children pass through a stage of gender appearance rigidity; girls insist on wearing dresses, often pink and frilly, whereas boys refuse to wear anything with a hint of femininity. In 2 studies, we investigated the prevalence of this apparent hallmark of early gender development and its relation to children's growing identification with a gender category. Study 1a examined the prevalence of this behavior and whether it would exhibit a developmental pattern of rigidity followed by flexibility, consistent with past research on identity-related cognitions. Interviews with 76 White, middle-class parents and their 3- to 6-year-old children revealed that about two thirds of parents of 3- and 4-year-old girls and almost half (44%) of parents of 5- and 6-year-old boys reported that their children had exhibited a period of rigidity in their gender-related appearance behavior. Appearance rigidity was not related to parents' preferences for their children's gender-typed clothing. Study 1b examined whether cognitive theories of identity development could shed light on gender appearance rigidity. The more important and positive children considered their gender and the more children understood that gender categories remain stable over time (gender stability), the more likely children were to wear gender-typed outfits. In Study 2, we extended this research to a more diverse population and found that gender appearance rigidity was also prevalent in 267 4-year-old children in the United States from African American, Chinese, Dominican, and Mexican immigrant low-income backgrounds. Results suggest that rigid gender-related appearance behavior can be seen among young children from different backgrounds and might reflect early developing cognitions about gender identity. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  15. Rigid fixation improves outcomes of spinal fusion for C1-C2 instability in children with skeletal dysplasias.

    PubMed

    Helenius, Ilkka; Crawford, Haemish; Sponseller, Paul D; Odent, Thierry; Bernstein, Robert M; Stans, Anthony A; Hedequist, Daniel; Phillips, Jonathan H

    2015-02-04

    Upper cervical instability is common in many skeletal dysplasias, and surgical treatment can be difficult because of small, fragile osseous elements. In this study of children with skeletal dysplasia and upper cervical instability, we compared fusion rates and complications between (1) patients treated with no instrumentation or with wiring techniques and (2) those who underwent rigid cervical spine instrumentation. We also sought to characterize the presentation and common parameters of upper cervical instability in this population. A multicenter study identified twenty-eight children with skeletal dysplasia who underwent surgery from 2000 through 2011 for C1-C2 instability and were followed for a minimum of two years. Fourteen children were treated with no instrumentation or with instrumentation with wires or cables (nonrigid-fixation group) and fourteen were treated with screws (or hooks) and rods (rigid-fixation group). All patients received autograft, and twenty (twelve in the nonrigid group and eight in the rigid group) were treated with a halo-body jacket. Fourteen children had C1-C2 fusion, and fourteen had occipitocervical fusion. Eleven (39%) underwent spinal cord decompression. The nonunion rate was significantly higher in the nonrigid-fixation group (six of fourteen) than in the rigid-fixation group (zero of fourteen; p = 0.0057). Complications, including nonunion, occurred in nine patients in the nonrigid group and one patient in the rigid group. However, two of the complications in the nonrigid-fixation group were vertebral artery bleeding episodes that actually occurred during an attempt at rigid fixation (the fixation was subsequently done with wiring). No new neurologic deficits were observed. Five of the seven children with a preoperative neurologic deficit showed at least partial recovery, with significant improvement in the Japanese Orthopaedic Association upper-extremity score (p = 0.047). The nonunion rate is relatively high after patients

  16. Error analysis of analytic solutions for self-excited near-symmetric rigid bodies - A numerical study

    NASA Technical Reports Server (NTRS)

    Kia, T.; Longuski, J. M.

    1984-01-01

    Analytic error bounds are presented for the solutions of approximate models for self-excited near-symmetric rigid bodies. The error bounds are developed for analytic solutions to Euler's equations of motion. The results are applied to obtain a simplified analytic solution for Eulerian rates and angles. The results of a sample application of the range and error bound expressions for the case of the Galileo spacecraft experiencing transverse torques demonstrate the use of the bounds in analyses of rigid body spin change maneuvers.

  17. A rigid lamb syndrome in sheep in Rhodesia.

    PubMed

    Rudert, C P; Lawrence, J A; Foggin, C; Barlow, R M

    1978-04-29

    A syndrome characterised by the birth of lambs with varying degrees of rigidity of the limbs and spine has been encountered on several occasions in Rhodesia. Outbreaks have occurred in autumn-born lambs from Dorper ewes grazing heavily fertilised Star grass cv No 2 (Cynodon aethiopicus) pastures. The condition appears to be exacerbated by the application of sulphur to the pasture and is partly prevented by the administration of selenium and vitamin E to the ewes before lambing. The aetiology is unknown.

  18. Attitude stabilization of a rigid spacecraft using two momentum wheel actuators

    NASA Technical Reports Server (NTRS)

    Krishnan, Hariharan; Mcclamroch, N. Harris; Reyhanoglu, Mahmut

    1993-01-01

    It is well known that three momentum wheel actuators can be used to control the attitude of a rigid spacecraft and that arbitrary reorientation maneuvers of the spacecraft can be accomplished using smooth feedback. If failure of one of the momentum wheel actuators occurs, it is demonstrated that two momentum wheel actuators can be used to control the attitude of a rigid spacecraft and that arbitrary reorientation maneuvers of the spacecraft can be accomplished. Although the complete spacecraft equations are not controllable, the spacecraft equations are small time locally controllable in a reduced nonlinear sense. The reduced spacecraft dynamics cannot be asymptotically stabilized to any equilibrium attitude using a time-variant continuous feedback control law, but discontinuous feedback control strategies are constructed which stabilize any equilibrium attitude of the spacecraft in finite time. Consequently, reorientation of the spacecraft can be accomplished using discontinuous feedback control.

  19. Analytic analysis of auxetic metamaterials through analogy with rigid link systems

    NASA Astrophysics Data System (ADS)

    Rayneau-Kirkhope, Daniel; Zhang, Chengzhao; Theran, Louis; Dias, Marcelo A.

    2018-02-01

    In recent years, many structural motifs have been designed with the aim of creating auxetic metamaterials. One area of particular interest in this subject is the creation of auxetic material properties through elastic instability. Such metamaterials switch from conventional behaviour to an auxetic response for loads greater than some threshold value. This paper develops a novel methodology in the analysis of auxetic metamaterials which exhibit elastic instability through analogy with rigid link lattice systems. The results of our analytic approach are confirmed by finite-element simulations for both the onset of elastic instability and post-buckling behaviour including Poisson's ratio. The method gives insight into the relationships between mechanisms within lattices and their mechanical behaviour; as such, it has the potential to allow existing knowledge of rigid link lattices with auxetic paths to be used in the design of future buckling-induced auxetic metamaterials.

  20. The modern history and evolution of percutaneous nephrolithotomy.

    PubMed

    Patel, Sutchin R; Nakada, Stephen Y

    2015-02-01

    Serendipity, innovative physicians, evolving techniques for renal access, and improvements in equipment and radiology led to the evolution of percutaneous nephrolithotomy (PCNL). We searched urology texts and the literature for sources pertaining to the history and development of PCNL. In 1941, Rupel and Brown performed the first nephroscopy when a rigid cystoscope was passed into the kidney following open surgery. Willard Goodwin, in 1955, while trying to perform a renal arteriogram, placed a needle into the collecting system of a hydronephrotic kidney and performed the first antegrade nephrostogram. He left a tube to drain the kidney, thereby placing the first nephrostomy tube. By 1976, Fernström and Johansson were the first to describe a technique for extracting renal calculi through a percutaneous nephrostomy under radiological control. In 1978, Arthur Smith, would describe the first antegrade stent placement when he introduced a Gibbons stent through a percutaneous nephrostomy in a patient with a reimplanted ureter. Dr. Smith would coin the term "endourology" to describe closed, controlled manipulation of the genitourinary tract. His collaboration with Kurt Amplatz, an interventional radiologist and medical inventor, would lead to numerous innovations that would further advance PCNL. In the 1980s the process of renal access and tract dilation was improved upon and the use of a rigid cystoscope was replaced by offset nephroscopes with a large straight working channel. Radiographic innovations, including improvements in fluoroscopy would further aid in renal access. The development of various lithotripsy devices and the introduction of the holmium laser improved the efficiency of stone fragmentation and clearance. The increased clinical experience and utilization of PCNL would lead to the characterization of stone-free rates and complications for the procedure. Serendipity, innovations in renal access, optics, radiology, and improvements in lithotripsy all

  1. Jets from pulsed-ultrasound-induced cavitation bubbles near a rigid boundary

    NASA Astrophysics Data System (ADS)

    Brujan, Emil-Alexandru

    2017-06-01

    The dynamics of cavitation bubbles, generated from short (microsecond) pulses of ultrasound and situated near a rigid boundary, are investigated numerically. The temporal development of the bubble shape, bubble migration, formation of the liquid jet during bubble collapse, and the kinetic energy of the jet are investigated as a function of the distance between bubble and boundary. During collapse, the bubble migrates towards the boundary and the liquid jet reaches a maximum velocity between 80 m s-1 and 120 m s-1, depending on the distance between bubble and boundary. The conversion of bubble energy to kinetic energy of the jet ranges from 16% to 23%. When the bubble is situated in close proximity to the boundary, the liquid jet impacts the boundary with its maximum velocity, resulting in an impact pressure of the order of tens of MPa. The rapid expansion of the bubble, the impact of the liquid jet onto the nearby boundary material, and the high pressure developed inside the bubble at its minimum volume can all contribute to the boundary material damage. The high pressure developed during the impact of the liquid jet onto the biological material and the shearing forces acting on the material surface as a consequence of the radial flow of the jet outward from the impact site are the main damage mechanisms of rigid biological materials. The results are discussed with respect to cavitation damage of rigid biological materials, such as disintegration of renal stones and calcified tissue and collateral effects in pulsed ultrasound surgery.

  2. Effects of rigid fixation on the growing neurocranium of immature rabbits.

    PubMed

    Sanus, Galip Zihni; Tanriverdi, Taner; Kacira, Tibet; Jackson, Ian T

    2007-03-01

    The improved intraoperative long-term skeletal stability achieved with rigid fixation techniques has led to their widespread popularity and application. However, experimental studies have revealed some drawbacks related to metallic implants and long-term results of clinical studies, especially in pediatric patients, has confirmed the results of experimental studies. Our aim in this experimental study using an infant rabbit model is to answer the following question: "Does short-term skeletal stability cause long-term growth inhibition?" Forty, 9-day-old New Zealand white albino rabbits were divided into four groups: 1) experimental, n=6: plated across the right coronal suture and two screws on each side of the left coronal suture; 2) re-operation, n=6: the same materials as group I were placed, and only the plate was removed at the end of 1 month; 3) sham, n=6: sham control with simulated surgery and two screws on each side of the left coronal suture; 4) control, n=2: no operation. The animals were killed 6 months after microplate application, and the skulls were evaluated both grossly and cephalometrically. Gross examination showed that the plates and the screws were covered by bony overgrowth and caused bony irregularity and regional bone degeneration. The parietal bones on the plated sides became striated and lost their concave shape. Cephalometric analysis demonstrated overt mastoid tip deviation toward, or shortening of cranionasal length on, the side with rigid fixation. We conclude from our study that rigid fixation during skeletal development causes growth retardation and should not be used in the growing child.

  3. Improving the Perception of Self-Sufficiency towards Creative Drama

    ERIC Educational Resources Information Center

    Pekdogan, Serpil; Korkmaz, Halil Ibrahim

    2016-01-01

    The purpose of this study is to investigate the effects of a Creative Drama Based Perception of Self-sufficiency Skills Training Program on 2nd grade bachelor degree students' (who are attending a preschool teacher training program) perception of self-sufficiency. This is a quasi-experimental study. Totally 50 students were equally divided into…

  4. Conformational Rigidity and Protein Dynamics at Distinct Timescales Regulate PTP1B Activity and Allostery.

    PubMed

    Choy, Meng S; Li, Yang; Machado, Luciana E S F; Kunze, Micha B A; Connors, Christopher R; Wei, Xingyu; Lindorff-Larsen, Kresten; Page, Rebecca; Peti, Wolfgang

    2017-02-16

    Protein function originates from a cooperation of structural rigidity, dynamics at different timescales, and allostery. However, how these three pillars of protein function are integrated is still only poorly understood. Here we show how these pillars are connected in Protein Tyrosine Phosphatase 1B (PTP1B), a drug target for diabetes and cancer that catalyzes the dephosphorylation of numerous substrates in essential signaling pathways. By combining new experimental and computational data on WT-PTP1B and ≥10 PTP1B variants in multiple states, we discovered a fundamental and evolutionarily conserved CH/π switch that is critical for positioning the catalytically important WPD loop. Furthermore, our data show that PTP1B uses conformational and dynamic allostery to regulate its activity. This shows that both conformational rigidity and dynamics are essential for controlling protein activity. This connection between rigidity and dynamics at different timescales is likely a hallmark of all enzyme function. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Skin wrinkles and rigidity in early postmenopausal women vary by race/ethnicity: baseline characteristics of the skin ancillary study of the KEEPS trial.

    PubMed

    Wolff, Erin; Pal, Lubna; Altun, Tugba; Madankumar, Rajeevi; Freeman, Ruth; Amin, Hussein; Harman, Mitch; Santoro, Nanette; Taylor, Hugh S

    2011-02-01

    To characterize skin wrinkles and rigidity in recently menopausal women. Baseline assessment of participants before randomization to study drug. Multicenter trial, university medical centers. Recently menopausal participants enrolled in the Kronos Early Estrogen Prevention Study (KEEPS). Skin wrinkles were assessed at 11 locations on the face and neck using the Lemperle wrinkle scale. Skin rigidity was assessed at the forehead and cheek using a durometer. Skin wrinkles and rigidity were compared among race/ethnic groups. Skin wrinkles and rigidity were correlated with age, time since menopause, weight, and body mass index (BMI). In early menopausal women, wrinkles, but not skin rigidity, vary significantly among races, where black women have the lowest wrinkle scores. In white women, chronological age was significantly correlated with worsening skin wrinkles, but not with rigidity. Skin rigidity correlated with increasing length of time since menopause, however, only in the white subgroup. In the combined study group, increasing weight was associated with less skin wrinkling. Skin characteristics of recently menopausal women are not well studied. Ethnic differences in skin characteristics are widely accepted, but poorly described. In recently menopausal women not using hormone therapy (HT), significant racial differences in skin wrinkling and rigidity exist. Continued study of the KEEPS population will provide evidence of the effects of HT on the skin aging process in early menopausal women. Copyright © 2011 American Society for Reproductive Medicine. All rights reserved.

  6. Awake craniotomy using electromagnetic navigation technology without rigid pin fixation.

    PubMed

    Morsy, Ahmed A; Ng, Wai Hoe

    2015-11-01

    We report our institutional experience using an electromagnetic navigation system, without rigid head fixation, for awake craniotomy patients. The StealthStation® S7 AxiEM™ navigation system (Medtronic, Inc.) was used for this technique. Detailed preoperative clinical and neuropsychological evaluations, patient education and contrast-enhanced MRI (thickness 1.5mm) were performed for each patient. The AxiEM Mobile Emitter was typically placed in a holder, which was mounted to the operating room table, and a non-invasive patient tracker was used as the patient reference device. A monitored conscious sedation technique was used in all awake craniotomy patients, and the AxiEM Navigation Pointer was used for navigation during the procedure. This offers the same accuracy as optical navigation, but without head pin fixation or interference with intraoperative neurophysiological techniques and surgical instruments. The application of the electromagnetic neuronavigation technology without rigid head fixation during an awake craniotomy is accurate, and offers superior patient comfort. It is recommended as an effective adjunctive technique for the conduct of awake surgery. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. A Soft Gripper with Rigidity Tunable Elastomer Strips as Ligaments.

    PubMed

    Nasab, Amir Mohammadi; Sabzehzar, Amin; Tatari, Milad; Majidi, Carmel; Shan, Wanliang

    2017-12-01

    Like their natural counterparts, soft bioinspired robots capable of actively tuning their mechanical rigidity can rapidly transition between a broad range of motor tasks-from lifting heavy loads to dexterous manipulation of delicate objects. Reversible rigidity tuning also enables soft robot actuators to reroute their internal loading and alter their mode of deformation in response to intrinsic activation. In this study, we demonstrate this principle with a three-fingered pneumatic gripper that contains "programmable" ligaments that change stiffness when activated with electrical current. The ligaments are composed of a conductive, thermoplastic elastomer composite that reversibly softens under resistive heating. Depending on which ligaments are activated, the gripper will bend inward to pick up an object, bend laterally to twist it, and bend outward to release it. All of the gripper motions are generated with a single pneumatic source of pressure. An activation-deactivation cycle can be completed within 15 s. The ability to incorporate electrically programmable ligaments in a pneumatic or hydraulic actuator has the potential to enhance versatility and reduce dependency on tubing and valves.

  8. Non-rigid image registration using a statistical spline deformation model.

    PubMed

    Loeckx, Dirk; Maes, Frederik; Vandermeulen, Dirk; Suetens, Paul

    2003-07-01

    We propose a statistical spline deformation model (SSDM) as a method to solve non-rigid image registration. Within this model, the deformation is expressed using a statistically trained B-spline deformation mesh. The model is trained by principal component analysis of a training set. This approach allows to reduce the number of degrees of freedom needed for non-rigid registration by only retaining the most significant modes of variation observed in the training set. User-defined transformation components, like affine modes, are merged with the principal components into a unified framework. Optimization proceeds along the transformation components rather then along the individual spline coefficients. The concept of SSDM's is applied to the temporal registration of thorax CR-images using pattern intensity as the registration measure. Our results show that, using 30 training pairs, a reduction of 33% is possible in the number of degrees of freedom without deterioration of the result. The same accuracy as without SSDM's is still achieved after a reduction up to 66% of the degrees of freedom.

  9. ENERGETIC PARTICLE ANISOTROPIES AT THE HELIOSPHERIC BOUNDARY. II. TRANSIENT FEATURES AND RIGIDITY DEPENDENCE

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

    Florinski, V.; Roux, J. A. le; Stone, E. C.

    In the preceding paper, we showed that large second-order anisotropies of heliospheric ions measured by the Voyager 1 space probe during the August 2012 boundary crossing event could be explained by a magnetic shear across the heliopause preventing particles streaming along the magnetic field from escaping the inner heliosheath. According to Stone et al., the penetration distance of heliospheric ions into the outer heliosheath had a strong dependence on the particle’s Larmor radius. By comparing hydrogen, helium, and oxygen ions with the same energy per nucleon, these authors argued that this effect must be attributed to larger cyclotron radii ofmore » heavier species rather than differences in velocity. We propose that gradient drift in a nonuniform magnetic field was the cause of both the large second-order anisotropies and the spatial differentiation based on the ion’s rigidity. A latitudinal gradient of magnetic field strength of about 10% per AU between 2012.7 and 2012.9 could have provided drift motion sufficient to match both LECP and CRS Voyager 1 observations. We explain the transient intensity dropout observed prior to the heliocliff using flux tube structures embedded in the heliosheath and magnetically connected to interstellar space. Finally, this paper reports a new indirect measurement of the plasma radial velocity at the heliopause on the basis of the time difference between two cosmic-ray telescopes measuring the same intensity dropout.« less

  10. Sufficient conditions for uniqueness of the weak value

    NASA Astrophysics Data System (ADS)

    Dressel, J.; Jordan, A. N.

    2012-01-01

    We review and clarify the sufficient conditions for uniquely defining the generalized weak value as the weak limit of a conditioned average using the contextual values formalism introduced in Dressel, Agarwal and Jordan (2010 Phys. Rev. Lett. 104 240401). We also respond to criticism of our work by Parrott (arXiv:1105.4188v1) concerning a proposed counter-example to the uniqueness of the definition of the generalized weak value. The counter-example does not satisfy our prescription in the case of an underspecified measurement context. We show that when the contextual values formalism is properly applied to this example, a natural interpretation of the measurement emerges and the unique definition in the weak limit holds. We also prove a theorem regarding the uniqueness of the definition under our sufficient conditions for the general case. Finally, a second proposed counter-example by Parrott (arXiv:1105.4188v6) is shown not to satisfy the sufficiency conditions for the provided theorem.

  11. Reassessing Rogers' necessary and sufficient conditions of change.

    PubMed

    Watson, Jeanne C

    2007-09-01

    This article reviews the impact of Carl Rogers' postulate about the necessary and sufficient conditions of therapeutic change on the field of psychotherapy. It is proposed that his article (see record 2007-14630-002) made an impact in two ways; first, by acting as a spur to researchers to identify the active ingredients of therapeutic change; and, second, by providing guidelines for therapeutic practice. The role of the necessary and sufficient conditions in process-experiential therapy, an emotion-focused therapy for individuals, and their limitations in terms of research and practice are discussed. It is proposed that although the conditions are necessary and important in promoting clients' affect regulation, they do not take sufficient account of other moderating variables that affect clients' response to treatment and may need to be balanced with more structured interventions. Notwithstanding, Rogers highlighted a way of interacting with clients that is generally acknowledged as essential to effective psychotherapy practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved).

  12. Temperature Coefficient of the Modulus of Rigidity of Aircraft Instrument Diaphragm and Spring Materials

    NASA Technical Reports Server (NTRS)

    Brombacher, W G; Melton, E R

    1931-01-01

    Experimental data are presented on the variation of the modulus of rigidity in the temperature range -20 to +50 degrees C. of a number of metals which are of possible use for elastic elements for aircraft and other instruments. The methods of the torsional pendulum was used to determine the modulus of rigidity and its temperature coefficient for aluminum, duralumin, monel metal, brass, phosphor bronze, coin silver, nickel silver, three high carbon steels, and three alloy steels. It was observed that tensile stress affected the values of the modulus by amounts of 1 per cent or less.

  13. Mutual potential between two rigid bodies with arbitrary shapes and mass distributions

    NASA Astrophysics Data System (ADS)

    Hou, Xiyun; Scheeres, Daniel J.; Xin, Xiaosheng

    2017-03-01

    Formulae to compute the mutual potential, force, and torque between two rigid bodies are given. These formulae are expressed in Cartesian coordinates using inertia integrals. They are valid for rigid bodies with arbitrary shapes and mass distributions. By using recursive relations, these formulae can be easily implemented on computers. Comparisons with previous studies show their superiority in computation speed. Using the algorithm as a tool, the planar problem of two ellipsoids is studied. Generally, potential truncated at the second order is good enough for a qualitative description of the mutual dynamics. However, for ellipsoids with very large non-spherical terms, higher order terms of the potential should be considered, at the cost of a higher computational cost. Explicit formulae of the potential truncated to the fourth order are given.

  14. Efficient swimming of an assembly of rigid spheres at low Reynolds number.

    PubMed

    Felderhof, B U

    2015-08-01

    The swimming of an assembly of rigid spheres immersed in a viscous fluid of infinite extent is studied in low-Reynolds-number hydrodynamics. The instantaneous swimming velocity and rate of dissipation are expressed in terms of the time-dependent displacements of sphere centers about their collective motion. For small-amplitude swimming with periodically oscillating displacements, optimization of the mean swimming speed at given mean power leads to an eigenvalue problem involving a velocity matrix and a power matrix. The corresponding optimal stroke permits generalization to large-amplitude motion in a model of spheres with harmonic interactions and corresponding actuating forces. The method allows straightforward calculation of the swimming performance of structures modeled as assemblies of interacting rigid spheres. A model of three collinear spheres with motion along the common axis is studied as an example.

  15. Effects of Perforation on Rigid PU Foam Plates: Acoustic and Mechanical Properties

    PubMed Central

    Lin, Jia-Horng; Chuang, Yu-Chun; Li, Ting-Ting; Huang, Chen-Hung; Huang, Chien-Lin; Chen, Yueh-Sheng; Lou, Ching-Wen

    2016-01-01

    Factories today are equipped with diverse mechanical equipment in response to rapid technological and industrial developments. Industrial areas located near residential neighborhoods cause massive environmental problems. In particular, noise pollution results in physical and psychological discomfort, and is a seen as invisible and inevitable problem. Thus, noise reduction is a critical and urgent matter. In this study, rigid polyurethane (PU) foam plates undergo perforation using a tapping machine. The mechanical and acoustic properties of these perforated plates as related to perforation rate and perforation depth are evaluated in terms of compression strength, drop-weight impact strength, and sound absorption coefficient. Experimental results indicate that applying the perforation process endows the rigid PU foaming plates with greater load absorption and better sound absorption at medium and high frequencies. PMID:28774119

  16. A control approach for robots with flexible links and rigid end-effectors

    NASA Technical Reports Server (NTRS)

    Barbieri, Enrique; Ozguner, Umit

    1989-01-01

    Multiarm flexible robots with dexterous end effectors are currently being considered in such tasks as satellite retrieval, servicing and repair where a two phase problem can be identified: Phase 1, robot positioning in space; Phase 2, object retrieval. Some issues in Phase 1 regarding modelling and control strategies for a robotic system comprised of along flexible arm and a rigid three-link end effector are presented. The control objective is to maintain the last (rigid) link stationary in space in the presence of an additive disturbance caused by the flexible energy in the first link after a positioning maneuver has been accomplished. Several configuration strategies can be considered, and optimal decentralized servocompensators can be designed. Preliminary computer simulations are included for a simple proportional controller to illustrate the approach.

  17. Rigid Gas Permeable Contact Lens as a Vision-Sparing Tool in Children After Traumatic Corneal Laceration.

    PubMed

    Elseht, Rabab Mohamed; Nagy, Khaled Ahmed

    2018-05-01

    To evaluate the clinical value of rigid gas permeable contact lenses in children after traumatic corneal scarring. This comparative study included 15 children (age range: 5.7 to 14 years; mean ± standard deviation = 9.4 ± 2.9 years) with corneal scars and best corrected visual acuity (BCVA) of worse than 20/20, history of penetrating ocular trauma, and/or cataract extraction. All children were advised to wear spherical rigid gas permeable contact lenses for 6 months with a special regimen. Visual acuity was compared before and after fitting. The total and anterior surface aberrations of all children were measured using a corneal topographer before and after treatment. There was a significant improvement in the BCVA after wearing rigid gas permeable contact lenses compared to spectacle visual acuity (P = .001). There was also significant improvement of the keratometric astigmatism (P = .001) and corneal aberrations such as higher order aberrations (P = .008), lower order aberrations, root mean square, and point spread function (P = .001). The optical performance of rigid gas permeable contact lenses has been demonstrated to be effective in the visual rehabilitation of children with traumatic corneal lacerations. Corneal topography was an objective tool for detecting optical disorders. [J Pediatr Ophthalmol Strabismus. 2018;55(3):178-181.]. Copyright 2018, SLACK Incorporated.

  18. Stress analysis of the haunch region in a rigid frame bridge.

    DOT National Transportation Integrated Search

    1977-01-01

    The purpose of this study was to obtain an understanding of the behavior and stress distribution in the haunch region of a rigid frame highway bridge. A finite element model of the haunch of the bridge was developed to permit the prediction of stress...

  19. Water dynamics in rigid ionomer networks.

    PubMed

    Osti, N C; Etampawala, T N; Shrestha, U M; Aryal, D; Tyagi, M; Diallo, S O; Mamontov, E; Cornelius, C J; Perahia, D

    2016-12-14

    The dynamics of water within ionic polymer networks formed by sulfonated poly(phenylene) (SPP), as revealed by quasi-elastic neutron scattering (QENS), is presented. These polymers are distinguished from other ionic macromolecules by their rigidity and therefore in their network structure. QENS measurements as a function of temperature as the fraction of ionic groups and humidity were varied have shown that the polymer molecules are immobile while absorbed water molecules remain dynamic. The water molecules occupy multiple sites, either bound or loosely constrained, and bounce between the two. With increasing temperature and hydration levels, the system becomes more dynamic. Water molecules remain mobile even at subzero temperatures, illustrating the applicability of the SPP membrane for selective transport over a broad temperature range.

  20. Assessing sufficiency of thermal riverscapes for resilient ...

    EPA Pesticide Factsheets

    Resilient salmon populations require river networks that provide water temperature regimes sufficient to support a diversity of salmonid life histories across space and time. Efforts to protect, enhance and restore watershed thermal regimes for salmon may target specific locations and features within stream networks hypothesized to provide disproportionately high-value functional resilience to salmon populations. These include relatively small-scale features such as thermal refuges, and larger-scale features such as entire watersheds or aquifers that support thermal regimes buffered from local climatic conditions. Quantifying the value of both small and large scale thermal features to salmon populations has been challenged by both the difficulty of mapping thermal regimes at sufficient spatial and temporal resolutions, and integrating thermal regimes into population models. We attempt to address these challenges by using newly-available datasets and modeling approaches to link thermal regimes to salmon populations across scales. We will describe an individual-based modeling approach for assessing sufficiency of thermal refuges for migrating salmon and steelhead in large rivers, as well as a population modeling approach for assessing large-scale climate refugia for salmon in the Pacific Northwest. Many rivers and streams in the Pacific Northwest are currently listed as impaired under the Clean Water Act as a result of high summer water temperatures. Adverse effec