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Sample records for rigid nephroscopy sufficient

  1. Laparoscopic - assisted transpyelic rigid nephroscopy - simple alternative when flexible ureteroscopy is not available

    PubMed Central

    Tobias-Machado, Marcos; Hidaka, Alexandre Kiyoshi; Nunes-Silva, Igor; Chagas, Carlos Alberto; Leal, Leandro Correa; Pompeo, Antonio Carlos Lima

    2016-01-01

    ABSTRACT Introduction: In special situations such as malrotated or ectopic kidneys and UPJ stenosis treatment of renal lithiasis can be challenging. In these rare cases laparoscopy can be indicated. Objective: Describe the Laparoscopic-assisted rigid nephroscopy performed via transpyelic approach and report the feasibility. Patients and methods: We present two cases of caliceal lithiasis. The first is a patient that ESWL and previous percutaneous lithotripsy have failed, with pelvic kidney where laparoscopic dissection of renal pelvis was carried out followed by nephroscopy utilizing the 30 Fr rigid nephroscope to remove the calculus. Ideal angle between the major axis of renal pelvis and the rigid nephroscope to allow success with this technique was 60-90 grades. In the second case, the kidney had a dilated infundibulum. Results: The operative time was 180 minutes for both procedures. No significant blood loss or perioperative complications occurred. The bladder catheter was removed in the postoperative day 1 and Penrose drain on day 2 when patients were discharged. The convalescence was completed after 3 weeks. Patients were stone free without symptons in one year of follow-up. Conclusions: Laparoscopic-assisted rigid nephroscopy performed via tranpyelic approach can be done safely with proper patient selection and adherence to standard laparoscopic surgical principles. This approach is an alternative in cases where flexible endoscope is not available and when standard procedure is unlikely to produce a stone-free status. PMID:27564304

  2. Laparoscopic Stone Surgery With the Aid of Flexible Nephroscopy

    PubMed Central

    Jung, Jae Hyun; Cho, Sung Yong; Jeong, Chang Wook; Jeong, Hyeon; Son, Hwancheol; Woo, Seung Hyo; Kim, Dae Kyung; Min, Sun-Ho; Oh, Seung-June; Kim, Hyeon-Hoe

    2014-01-01

    Purpose To report the outcome of laparoscopic pyelo- and ureterolithotomies with the aid of flexible nephroscopy. Materials and Methods A retrospective analysis was performed in 71 patients with complex renal stones or large and impacted proximal ureteral stones. Patients underwent laparoscopic pyelo- or ureterolithotomies with or without the removal of small residual stones by use of flexible nephroscopy between July 2005 and July 2010. Operative success was defined as no residual stones in the intravenous pyelogram at 12 weeks postoperatively. Perioperative results and surgical outcomes were analyzed. Results The patients' mean age was 54.7±13.7 years, and 53 males (74.6%) and 18 females (25.4%) were included. The mean maximal stone size was 19.4±9.4 mm. A total of 47 cases were complex renal stones and 24 cases were impacted ureteral stones. Mean operative time was 139.0±63.7 minutes. Stones were completely removed in 61 cases (85.9%), and no further ancillary treatment was needed for clinically insignificant residual fragments in 7 cases (9.9%). For complex renal stones, the complete stone-free rate and clinically significant stone-free rate were 80.9% and 93.6%, respectively. Multivariate analysis showed that the use of flexible nephroscopy for complex renal stones can reduce the risk of residual stones. A major complication occurred in one case, in which open conversion was performed. Conclusions Laparoscopic stone surgery is a safe and minimally invasive procedure with a high success rate, especially with the aid of flexible nephroscopy, and is not associated with procedure-specific complications. PMID:25045447

  3. Laparoscopic stone surgery with the aid of flexible nephroscopy.

    PubMed

    Jung, Jae Hyun; Cho, Sung Yong; Jeong, Chang Wook; Jeong, Hyeon; Son, Hwancheol; Woo, Seung Hyo; Kim, Dae Kyung; Min, Sun-Ho; Oh, Seung-June; Kim, Hyeon-Hoe; Lee, Seung Bae

    2014-07-01

    To report the outcome of laparoscopic pyelo- and ureterolithotomies with the aid of flexible nephroscopy. A retrospective analysis was performed in 71 patients with complex renal stones or large and impacted proximal ureteral stones. Patients underwent laparoscopic pyelo- or ureterolithotomies with or without the removal of small residual stones by use of flexible nephroscopy between July 2005 and July 2010. Operative success was defined as no residual stones in the intravenous pyelogram at 12 weeks postoperatively. Perioperative results and surgical outcomes were analyzed. The patients' mean age was 54.7±13.7 years, and 53 males (74.6%) and 18 females (25.4%) were included. The mean maximal stone size was 19.4±9.4 mm. A total of 47 cases were complex renal stones and 24 cases were impacted ureteral stones. Mean operative time was 139.0±63.7 minutes. Stones were completely removed in 61 cases (85.9%), and no further ancillary treatment was needed for clinically insignificant residual fragments in 7 cases (9.9%). For complex renal stones, the complete stone-free rate and clinically significant stone-free rate were 80.9% and 93.6%, respectively. Multivariate analysis showed that the use of flexible nephroscopy for complex renal stones can reduce the risk of residual stones. A major complication occurred in one case, in which open conversion was performed. Laparoscopic stone surgery is a safe and minimally invasive procedure with a high success rate, especially with the aid of flexible nephroscopy, and is not associated with procedure-specific complications.

  4. Rigid-only versus combined rigid and flexible percutaneous nephrolithotomy: a systematic review.

    PubMed

    Cracco, Cecilia M; Knoll, Thomas; Liatsikos, Evangelos N; Osther, Palle J; Smith, Arthur D; Scarpa, Roberto M; Scoffone, Cesare M

    2017-08-01

    Percutaneous nephrolithotomy (PNL) is usually performed worldwide with a rigid-only antegrade approach. Daily practice suggests that adding flexible nephroscopy and/or ureteroscopy to conventional rigid PNL might improve its efficacy and safety, but available evidence is weak. Appraisal of reliable outcomes of such PNL techniques would better guide intraoperative choices and optimize surgical results. Therefore, our objective was to systematically review relevant literature comparing the outcomes of rigid-only PNL and combined flexible PNLs (adding flexible nephroscopy and/or flexible ureteroscopy) for the treatment of large and/or complex upper urinary tract calculi, with regard to efficacy and safety. Ovid MedLine, PubMed, Scopus and Web of Science databases were searched in August 2016 to identify relevant studies. Article selection was performed according to the Preferred Reporting Items for Systematic Review and Meta-analysis criteria. Six articles reporting on 666 patients were included: two randomized controlled trials, two retrospective comparative studies and two case series ≥50 patients (one prospective and one retrospective). A narrative synthesis of minor evidences was also prepared. The adjunct of flexible nephroscopy and/or ureteroscopy provided better stone-free rates (range 86.7-96.97%), through a single percutaneous access most of the times and in any position, reducing the need for second-look procedures. Safety of the combined flexible procedures was improved to a variable degree, with a consensual reduction of the mean hospital stay (range 5.1-7 days). The current evidence suggests that patients with large and/or complex urolithiasis might benefit from the adjunct of flexible nephroscopy and/or ureteroscopy to rigid PNL.

  5. 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.

  6. Laparoscopic Pyeloplasty and Flexible Nephroscopy: Simultaneous Treatment of Ureteroplevic Junction Obstruction and Nephrolithiasis

    PubMed Central

    Ball, Adam J.; Patel, Vipul R.; Wong, Carson

    2004-01-01

    Background and Objective: Ureteropelvic junction obstruction and concomitant calculus disease may coexist. Therapeutic controversy exists regarding their ideal management. We report our use of flexible nephroscopy during laparoscopic pyeloplasty for caliceal stone removal. Methods: From August 1998 through May 2002, 50 laparoscopic pyeloplasties were performed. Seven patients had documented ureteropelvic junction obstruction and ipsilateral nephrolithiasis. Preoperative stone burden and location were assessed. After pyelotomy, a 16 Fr flexible endoscope was passed through the uppermost trocar under direct laparoscopic guidance into the collecting system. Stone extraction was performed with a 2.4 Fr Nitinol basket. Postoperative imaging was assessed. Results: Complete stone-free status confirmed by postoperative imaging was achieved in 6 of 7 patients. The longest individual stone diameter ranged from 4 mm to 13 mm (mean, 10.3 mm), and an average of 2.5 stones per patient was removed (range, 1 to 4 stones). Neither intraoperative fluoroscopy nor lithotripsy was required. No intraoperative or delayed complications were noted during a mean follow-up of 8.5 months (range, 2 to 17 months). Conclusions: Laparoscopic pyeloplasty and concomitant flexible nephroscopy with basket extraction is a simple, attractive alternative for the simultaneous treatment of ureteropelvic junction obstruction presenting with coexisting nephrolithiasis. It appears more efficacious when the stone number is limited and diameters measure from 5 mm to 20 mm. PMID:15347108

  7. Abdominal rigidity

    MedlinePlus

    Rigidity of the abdomen ... is a sore area inside the belly or abdomen, the pain will get worse when a hand ... Causes can include: Abscess inside the abdomen Appendicitis ... small intestine, large bowel, or gallbladder ( gastrointestinal ...

  8. Rotating rigid motion in general relativity

    SciTech Connect

    Mason, D.P.; Pooe, C.A.

    1987-11-01

    Kinematic and dynamic expressions are derived for the Lie derivative of vorticity along a particle world line in a rigid motion. It is found that the evolution of vorticity in a rigid motion is governed by the electric part of the Weyl tensor. Necessary and sufficient kinematic and dynamic conditions are established for a rotating rigid motion to be isometric.

  9. Birationally rigid Fano fibrations

    NASA Astrophysics Data System (ADS)

    Pukhlikov, A. V.

    2000-06-01

    We prove the birational superrigidity of a general Fano fibration \\pi\\colon V\\to\\mathbf P^1 whose fibre is a Fano hypersurface W_M\\subset\\mathbf P^M of index 1. If the fibration is sufficiently twisted over the base \\mathbf P^1, then V has no other structure of a fibration into rationally connected varieties. We also formulate and discuss conjectures on birational rigidity for a large class of Fano varieties and Fano fibrations over a base of arbitrary dimension.

  10. 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...

  11. 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...

  12. Rigid particulate matter sensor

    SciTech Connect

    Hall, Matthew

    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.

  13. Self-Sufficiency Resources.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

    These instructional materials were developed as a supplement to the "Alaska State Model Curriculum in Renewable Natural Resources/Agriculture." The topics covered focus on competencies from the curriculum for which materials were not readily available to Alaskan teachers and provide information that may not be sufficiently covered by…

  14. 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.

  15. 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.

  16. Colonoscope flexural rigidity measurement.

    PubMed

    Wehrmeyer, J A; Barthel, J A; Roth, J P; Saifuddin, T

    1998-07-01

    A testing device is developed that determines the stiffness, or flexural rigidity, of an endoscope at specific locations down its length by subjecting it to a compressive axial force, a situation similar to the actual forces applied to the endoscope during a clinical procedure. The endoscope is made to deform in a similar fashion to a slender buckled column and the force causing this deformation is related to the flexural rigidity using column buckling theory. A direct relationship between the critical load needed to cause buckling and the square of column length L is demonstrated experimentally and is expected theoretically, giving confidence in the application of column buckling theory to endoscope testing. Additional confidence in the validity of the column buckling test results is obtained by their similarity to data obtained by subjecting the endoscope to a transverse load, determining deflection, and modelling the endoscope as a bent elastic beam. Several makes and models of endoscopes were tested, with flexural rigidity values typically ranging between 160 to 240 Ncm2. The effect of a metal stiffener inserted in an endoscope's accessory channel is quantified, as is the change in flexural rigidity down the insertion shaft of a graded-stiffness endoscope. Significant differences in flexural rigidity were obtained between identical endoscopes, each sharing similar usage histories, indicating the need for flexural rigidity measurements for each individual endoscope of a particular model line, though a more extensive study is required to reliably determine scope-to-scope stiffness variations for a particular model line.

  17. Characterizations of linear sufficient statistics

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    A necessary and sufficient condition is developed such that there exists a continous linear sufficient statistic T for a dominated collection of totally finite measures defined on the Borel field generated by the open sets of a Banach space X. In particular, corollary necessary and sufficient conditions are given so that there exists a rank K linear sufficient statistic T for any finite collection of probability measures having n-variate normal densities. In this case a simple calculation, involving only the population means and covariances, determines the smallest integer K for which there exists a rank K linear sufficient statistic T (as well as an associated statistic T itself).

  18. Rigid molecular foams

    SciTech Connect

    Steckle, W.P. Jr.; Mitchell, M.A.; Aspen, P.G.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Organic analogues to inorganic zeolites would be a significant step forward in engineered porous materials and would provide advantages in range, selectivity, tailorability, and processing. Rigid molecular foams or {open_quotes}organic zeolites{close_quotes} would not be crystalline materials and could be tailored over a broader range of pore sizes and volumes. A novel process for preparing hypercrosslinked polymeric foams has been developed via a Friedel-Crafts polycondensation reaction. A series of rigid hypercrosslinked foams have been prepared using simple rigid polyaromatic hydrocarbons including benzene, biphenyl, m-terphenyl, diphenylmethane, and polystyrene, with dichloroxylene (DCX) as the pore size. After drying the foams are robust and rigid. Densities of the resulting foams can range from 0.15 g/cc to 0.75 g/cc. Nitrogen adsorption studies have shown that by judiciously selecting monomers and the crosslinking agent along with the level of crosslinking and the cure time of the resulting gel, the pore size, pore size distribution, and the total surface area of the foam can be tailored. Surface areas range from 160 to 1,200 m{sup 2}/g with pore sizes ranging from 6 {angstrom} to 2,000 {angstrom}.

  19. Rigid lenses: an overview.

    PubMed

    Bayshore, C A

    1979-03-01

    New gas permeable rigid contact lens materials, by allowing direct transmission of oxygen, provide significant advantages over PMMA. Edema resulting from oxygen deprivation with PMMA lenses is eliminated and comfort is increased. Three types of gas permeable materials are described: CAB, silicone, and a combination of CAB and silicone.

  20. Electrostatics of Rigid Polyelectrolytes

    SciTech Connect

    Wong, G.C.L.

    2009-06-04

    The organization of rigid biological polyelectrolytes by multivalent ions and macroions are important for many fundamental problems in biology and biomedicine, such as cytoskeletal regulation and antimicrobial sequestration in cystic fibrosis. These polyelectrolytes have been used as model systems for understanding electrostatics in complex fluids. Here, we review some recent results in theory, simulations, and experiments.

  1. Obituary--rigid contact lenses.

    PubMed

    Efron, Nathan

    2010-10-01

    Scleral and corneal rigid lenses represented 100 per cent of the contact lens market immediately prior to the invention of soft lenses in the mid-1960s. In the United Kingdom today, rigid lenses comprise 2 per cent of all new lens fits. Low rates of rigid lens fitting are also apparent in 27 other countries which have recently been surveyed. Thus, the 1998 prediction of the author that rigid lenses--also referred to as 'rigid gas permeable' (RGP) lenses or 'gas permeable' (GP) lenses--would be obsolete by the year 2010 has essentially turned out to be correct. In this obituary, the author offers 10 reasons for the demise of rigid lens fitting: initial rigid lens discomfort; intractable rigid lens-induced corneal and lid pathology; extensive soft lens advertising; superior soft lens fitting logistics; lack of rigid lens training opportunities; redundancy of the rigid lens 'problem solver' function; improved soft toric and bifocal/varifocal lenses; limited uptake of orthokeratology; lack of investment in rigid lenses; and the emergence of aberration control soft lenses. Rigid lenses are now being fitted by a minority of practitioners with specialist skills/training. Certainly, rigid lenses can no longer be considered as a mainstream form of contact lens correction. May their dear souls (bulk properties) rest in peace.

  2. How rigid are viruses

    NASA Astrophysics Data System (ADS)

    Hartschuh, R. D.; Wargacki, S. P.; Xiong, H.; Neiswinger, J.; Kisliuk, A.; Sihn, S.; Ward, V.; Vaia, R. A.; Sokolov, A. P.

    2008-08-01

    Viruses have traditionally been studied as pathogens, but in recent years they have been adapted for applications ranging from drug delivery and gene therapy to nanotechnology, photonics, and electronics. Although the structures of many viruses are known, most of their biophysical properties remain largely unexplored. Using Brillouin light scattering, we analyzed the mechanical rigidity, intervirion coupling, and vibrational eigenmodes of Wiseana iridovirus (WIV). We identified phonon modes propagating through the viral assemblies as well as the localized vibrational eigenmode of individual viruses. The measurements indicate a Young’s modulus of ˜7GPa for single virus particles and their assemblies, surprisingly high for “soft” materials. Mechanical modeling confirms that the DNA core dominates the WIV rigidity. The results also indicate a peculiar mechanical coupling during self-assembly of WIV particles.

  3. Dynamic rigidity transition

    NASA Astrophysics Data System (ADS)

    Åström, J. A.; Latva-Kokko, M.; Timonen, J.

    2003-01-01

    An inflated closed loop (or membrane) is used to demonstrate a dynamic rigidity transition that occurs when impact energy is added to the loop in static equilibrium at zero temperature. The only relevant parameter in this transition is the ratio of the energy needed to collapse the loop and the impact energy. When this ratio is below a threshold value close to unity, the loop collapses into a high-entropy floppy state, and it does not return to the rigid state unless the impact energy can escape. The internal oscillations are in the floppy state dominated by 1/f2 noise. When the ratio is above the threshold, the loop does not collapse, and the internal oscillations resulting from the impact are dominated by the eigenfrequencies of the stretched membrane. In this state, the loop can bounce for a long time. It is still an open question whether bouncing will eventually vanish or whether a stationary bouncing state will be reached. The dynamic transition between the floppy and the rigid state is discontinuous.

  4. 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.

  5. Number Rigidity in Superhomogeneous Random Point Fields

    NASA Astrophysics Data System (ADS)

    Ghosh, Subhro; Lebowitz, Joel

    2017-02-01

    We give sufficient conditions for the number rigidity of a large class of point processes in dimension d=1 and 2, based on the decay of correlations. Number rigidity implies that the probability distribution of the number of particles in a bounded domain Λ subset R^d, conditional on the configuration on Λ ^\\complement , is concentrated on a single integer N_Λ . Our conditions are: (a) ρ _1(x)= - int _{R^d} ρ _tr^{(2)}(x,y) dy for all x, where ρ _1 and ρ _tr^{(2)} are the intensity and the truncated pair correlation function resp., and (b)|ρ _tr^{(2)}(x,y)| is bounded by C_1[|x-y|+1]^{-2} in d=1 and by C_2[|x-y|+1]^{-(4+ɛ)} in d=2. Condition (a) covers a wide class of processes, including translation invariant or periodic point process on R^d, d=1,2, that are superhomogeneous or hyperuniform (that is the variance of the number of particles in a bounded domain Ω subset R^d grows slower than the volume of Ω ). It also covers determinantal point processes having a projection kernel. Our conditions for number rigidity are satisfied by all known processes with number rigidity in d=1,2. We also observe, in the light of the results of [26], that no such criteria exist in d>2.

  6. Spinal osteotomies for rigid deformities.

    PubMed

    Gupta, Munish C; Kebaish, Khalid; Blondel, Benjamin; Klineberg, Eric

    2013-04-01

    Various osteotomies are useful in making a rigid deformity flexible enough for realignment in coronal and sagittal plane. This article defines the osteotomies and their usefulness in treatment of specific rigid deformities. The pedicle subtraction osteotomy and vertebral column resection used in treating rigid deformities are described in detail. Copyright © 2013 Elsevier Inc. All rights reserved.

  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. 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.

  9. 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…

  10. 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.

  11. Repulsive Casimir force: Sufficient conditions

    SciTech Connect

    Rosa, Luigi; Lambrecht, Astrid

    2010-09-15

    In this paper the Casimir energy of two parallel plates made by materials of different penetration depth and no medium in between is derived. We study the Casimir force density and derive analytical constraints on the two penetration depths which are sufficient conditions to ensure repulsion. Compared to other methods our approach needs no specific model for dielectric or magnetic material properties and constitutes a complementary analysis.

  12. Origin of rigidity in athermal materials

    NASA Astrophysics Data System (ADS)

    Sarkar, Sumantra

    Solids are distinguished from fluids by their ability to resist shear. In traditional solids, the resistance to shear is associated with the emergence of broken translational symmetry as exhibited by a non-uniform density pattern, which results from either minimizing the energy cost or maximizing the entropy or both. In this thesis, we focus on a special class of materials where this paradigm is challenged. We argue that the observation of rigidity in dry granular materials, a representative system, is a collective process controlled solely by few constraints, e.g., the boundary stresses, the constraint of force and torque balance, and the positivity of contact forces. We have shown that these constraints lead to a broken translational symmetry in a dual space of heights (loop forces) which leads to the observed rigidity (jamming) in such a system. We investigate the structure and behavior of the dual space through a geometrical construction as the system evolves towards the rigidity transition, commonly known as jamming. In that context, we explore the role of friction in jamming and establish the equivalence of real space and stress space description. We conclude that the role of real space geometry is negligible, and a stress only description is sufficient to understand the phenomenology of jamming. In the second half of the thesis, we develop a phenomenological model of the shear induced rigidity in athermal materials. Recent studies of athermal systems such as dry grains and dense, non-Brownian suspensions have shown that shear can lead to solidification through the process of shear jamming in grains and discontinuous shear thickening in suspensions. The similarities observed between these two distinct phenomena suggest that the physical processes leading to shear-induced rigidity in athermal materials are universal. We present a non-equilibrium statistical mechanics model, which exhibits the phenomenology of these shear-driven transitions: shear jamming and

  13. 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.

  14. 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.

  15. International rigid contact lens prescribing.

    PubMed

    Efron, Nathan; Morgan, Philip B; Helland, Magne; Itoi, Motozumi; Jones, Deborah; Nichols, Jason J; van der Worp, Eef; Woods, Craig A

    2010-06-01

    Rigid lenses have been fitted less since the introduction of soft lenses nearly 40 years ago. Data that we have gathered from annual contact lens fitting surveys conducted in Australia, Canada, Japan, the Netherlands, Norway, the UK and the USA between 2000 and 2008 facilitate an accurate characterization of the pattern of the decline of rigid lens fitting during the first decade of this century. There is a trend for rigid lenses to be utilized primarily for refitting those patients who are already successful rigid lens wearers-most typically older females being refit with higher Dk materials. Rigid lenses are generally fitted on a full-time basis (four or more days of wear per week) without a planned replacement schedule. Orthokeratology is especially popular in the Netherlands, but is seldom prescribed in the other countries surveyed.

  16. Axial penile rigidity: determinants and relation to hemodynamic parameters.

    PubMed

    Goldstein, I; Udelson, D

    1998-05-01

    Erectile dysfunction may be defined in terms of axial penile rigidity, the physical property that enables the erection to be utilized as a penetration tool during sexual activity. Erectile dysfunction occurs when inadequate axial penile rigidity results in buckling of the penile column when subjected to axial compressive loading situations during vaginal intromission. New multi-disciplinary engineering studies of penile hemodynamic and structural dynamic relationships are reviewed concerning the determinants of axial penile rigidity. Axial penile rigidity develops as a continuum during the increases in intracavernosal pressure and volume changes from the flaccid state and is influenced by intracavernosal pressure, penile tissue mechanical properties and penile geometry. Two penile tissue mechanical properties are especially relevant; cavernosal maximum volume at relatively low intracavernosal pressure, and tunical distensibility, the relative volume of the fully erect to completely flaccid pendulous penis. Two penile geometric properties are critical; the penile aspect ratio, defined as the diameter to length ratio of the pendulous penis, and the magnitude of the flaccid penile diameter. Clinically measured values of axial buckling forces in patients undergoing dynamic pharmacocavernosometry strongly correlated to theoretic-based analytic derived magnitudes of axial penile rigidity based on these above pressure, tissue and geometric determinants. Since axial penile rigidity is not exclusively dependent upon intracavernosal pressure, patients with normal erectile hemodynamics may be erroneously labelled as having psychogenic dysfunction where their true pathophysiology may be related to abnormal penile tissue properties and/or penile geometric factors. Similarly, some patients may claim sufficient rigidity for penetration, but have abnormal hemodynamic erectile function studies. They may have uniquely advantageous tissue mechanical and/or geometric properties. More

  17. The structure of rigid functions

    NASA Astrophysics Data System (ADS)

    Balka, Richárd; Elekes, Márton

    2008-09-01

    A function is called vertically rigid if graph(cf) is isometric to graph(f) for all c[not equal to]0. We prove Jankovic's conjecture by showing that a continuous function is vertically rigid if and only if it is of the form a+bx or a+bekx (). We answer the question of Cain, Clark and Rose by showing that there exists a Borel measurable vertically rigid function which is not of the above form. We discuss the Lebesgue and Baire measurable case, consider functions bounded on some interval and functions with at least one point of continuity. We also introduce horizontally rigid functions, and show that a certain structure theorem can be proved without assuming any regularity.

  18. Energy Strategic Planning & Sufficiency Project

    SciTech Connect

    Retziaff, Greg

    2005-03-30

    This report provides information regarding options available, their advantages and disadvantages, and the costs for pursuing activities to advance Smith River Rancheria toward an energy program that reduces their energy costs, allows greater self-sufficiency and stimulates economic development and employment opportunities within and around the reservation. The primary subjects addressed in this report are as follows: (1) Baseline Assessment of Current Energy Costs--An evaluation of the historical energy costs for Smith River was conducted to identify the costs for each component of their energy supply to better assess changes that can be considered for energy cost reductions. (2) Research Viable Energy Options--This includes a general description of many power generation technologies and identification of their relative costs, advantages and disadvantages. Through this research the generation technology options that are most suited for this application were identified. (3) Project Development Considerations--The basic steps and associated challenges of developing a generation project utilizing the selected technologies are identified and discussed. This included items like selling to third parties, wheeling, electrical interconnections, fuel supply, permitting, standby power, and transmission studies. (4) Energy Conservation--The myriad of federal, state and utility programs offered for low-income weatherization and utility bill payment assistance are identified, their qualification requirements discussed, and the subsequent benefits outlined. (5) Establishing an Energy Organization--The report includes a high level discussion of formation of a utility to serve the Tribal membership. The value or advantages of such action is discussed along with some of the challenges. (6) Training--Training opportunities available to the Tribal membership are identified.

  19. Specifying spacecraft flexible appendage rigidity

    NASA Technical Reports Server (NTRS)

    Seltzer, S. M.; Shelton, H. L.

    1977-01-01

    As a method for specifying the required degree of rigidity of spacecraft flexible appendages, an analytical technique is proposed for establishing values for the frequency, damping ratio, and modal gain (deflection) of the first several bending modes. The shortcomings of the technique result from the limitations associated with the order of the equations that can be handled practically. An iterative method is prescribed for handling a system whose structural flexibility is described by more than one normal mode. The analytical technique is applied to specifying solar panel rigidity constraints for the NASA Space Telescope. The traditional nonanalytic procedure for specifying the required degree of rigidity of spacecraft flexible appendages has been to set a lower limit below which bending mode frequencies may not lie.

  20. 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

  1. Rigidly foldable origami gadgets and tessellations.

    PubMed

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

    2015-09-01

    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.

  2. Rigid gas permeable extended wear.

    PubMed

    Maehara, J R; Kastl, P R

    1994-04-01

    We have reviewed the pertinent literature on rigid gas permeable (RGP) extended wear contact lenses, and we discuss the benefits and adverse reactions of this contact lens modality, drawing conclusions from reviewed studies. We suggest parameters for success with these lenses and guidelines for the prevention of adverse reactions.

  3. 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.

  4. Torsional rigidity, isospectrality and quantum graphs

    NASA Astrophysics Data System (ADS)

    Colladay, Don; Kaganovskiy, Leon; McDonald, Patrick

    2017-01-01

    We study torsional rigidity for graph and quantum graph analogs of well-known pairs of isospectral non-isometric planar domains. We prove that such isospectral pairs are distinguished by torsional rigidity.

  5. Rigidity spectrum of Forbush decrease

    NASA Technical Reports Server (NTRS)

    Sakakibara, S.; Munakata, K.; Nagashima, K.

    1985-01-01

    Using data from neutron monitors and muon telescopes at surface and underground stations, the average rigidity spectrum of Forbush decreases (Fds) during the period of 1978-1982 were obtained. Thirty eight Ed-events are classified into two groups Hard Fd and Soft Fd according to size of Fd at Sakashita station. It is found that a spectral form of fractional-power type (P to the-gamma sub 1 (P+P sub c) to the -gamma sub2) is more suitable for the present purpose than that of power-exponential type or of power type with an upper limiting rigidity. The best fitted spectrum of fractional-power type is expressed by gamma sub1 = 0.37, gamma sub2 = 0.89 and P subc = 10 GV for Hard Fd and gamma sub1 = 0.77, gamma sub2 = 1.02 and P sub c - 14GV for Soft Fd.

  6. 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.

  7. Rigidly connected magnetic lines: twisting and winding of magnetic lines

    NASA Astrophysics Data System (ADS)

    Prasad, G.

    2017-10-01

    The dynamical process of magnetic flux variation in a fluid's stream tube is described by constructing 1+1+ (2) decomposition of the gradient of fluid's 4-velocity. The necessary and sufficient conditions are obtained for a spacelike congruence to be a congruence of rigidly connected spacelike curves. The evolution of magnetic flux in a magnetic tube is explored under the assumptions that magnetic lines are rigidly connected and the chemical potential of the fluid is constant along a magnetic tube. The interplay between magnetic and stream tubes is demonstrated. It is shown that the growth of magnetic energy in a magnetic tube cannot exceed to that of a stream tube. It is found that the proper time variation of twist of magnetic lines is caused by gravitation inside a neutron star if magnetic lines are rigidly connected and charge neutrality condition holds. Helmholtz-like magnetic vorticity flux conservation in a magnetic tube constituted by rigidly connected geodetic magnetic lines is derived under the assumption that the charge neutrality condition holds. It is shown that the winding of frozen-in poloidal magnetic field due to differential rotation requires meridional circulation in an axisymmetric stationary hydromagnetic configuration.

  8. 46 CFR 131.860 - Rigid liferafts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... for, as shown on its nameplate. (d) The rigid liferaft must be marked with the words “SOLAS A pack” or... 46 Shipping 4 2011-10-01 2011-10-01 false Rigid liferafts. 131.860 Section 131.860 Shipping COAST... Equipment and Emergency Equipment § 131.860 Rigid liferafts. (a) The following must be plainly marked or...

  9. 46 CFR 131.860 - Rigid liferafts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... for, as shown on its nameplate. (d) The rigid liferaft must be marked with the words “SOLAS A pack” or... 46 Shipping 4 2012-10-01 2012-10-01 false Rigid liferafts. 131.860 Section 131.860 Shipping COAST... Equipment and Emergency Equipment § 131.860 Rigid liferafts. (a) The following must be plainly marked or...

  10. 46 CFR 131.860 - Rigid liferafts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... for, as shown on its nameplate. (d) The rigid liferaft must be marked with the words “SOLAS A pack” or... 46 Shipping 4 2014-10-01 2014-10-01 false Rigid liferafts. 131.860 Section 131.860 Shipping COAST... Equipment and Emergency Equipment § 131.860 Rigid liferafts. (a) The following must be plainly marked or...

  11. 46 CFR 131.860 - Rigid liferafts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... for, as shown on its nameplate. (d) The rigid liferaft must be marked with the words “SOLAS A pack” or... 46 Shipping 4 2013-10-01 2013-10-01 false Rigid liferafts. 131.860 Section 131.860 Shipping COAST... Equipment and Emergency Equipment § 131.860 Rigid liferafts. (a) The following must be plainly marked or...

  12. 46 CFR 131.860 - Rigid liferafts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... for, as shown on its nameplate. (d) The rigid liferaft must be marked with the words “SOLAS A pack” or... 46 Shipping 4 2010-10-01 2010-10-01 false Rigid liferafts. 131.860 Section 131.860 Shipping COAST... Equipment and Emergency Equipment § 131.860 Rigid liferafts. (a) The following must be plainly marked or...

  13. Rigidity of complete noncompact bach-flat n-manifolds

    NASA Astrophysics Data System (ADS)

    Chu, Yawei; Feng, Pinghua

    2012-11-01

    Let (Mn,g) be a complete noncompact Bach-flat n-manifold with the positive Yamabe constant and constant scalar curvature. Assume that the L2-norm of the trace-free Riemannian curvature tensor R∘m is finite. In this paper, we prove that (Mn,g) is a constant curvature space if the L-norm of R∘m is sufficiently small. Moreover, we get a gap theorem for (Mn,g) with positive scalar curvature. This can be viewed as a generalization of our earlier results of 4-dimensional Bach-flat manifolds with constant scalar curvature R≥0 [Y.W. Chu, A rigidity theorem for complete noncompact Bach-flat manifolds, J. Geom. Phys. 61 (2011) 516-521]. Furthermore, when n>9, we derive a rigidity result for R<0.

  14. Volunteers for Refugee Self-Sufficiency.

    ERIC Educational Resources Information Center

    Phoenix Union High School District, AZ.

    The Volunteers for Refugee Self-Sufficiency (V-FoRSS) uses volunteers to meet the self-sufficiency needs of the refugee community in Phoenix, Arizona. The majority of the volunteers with V-FoRSS are home outreach tutors who provide English as a second language (ESL) and social adjustment skills instruction to adult Indochinese refugees. Classes…

  15. Some existence and sufficient conditions of optimality

    NASA Technical Reports Server (NTRS)

    Assefi, T.

    1976-01-01

    The role of the existence and sufficiency conditions in the field of optimal control was briefly described. The existence theorems are discussed for general nonlinear systems. However, the sufficiency conditions pertain to "nearly" linear systems with integral convex costs. Moreover, a brief discussion of linear systems with multiple-cost functions is presented.

  16. Rigid separator lead acid batteries

    SciTech Connect

    Cannone, A.G.; Salkind, A.J.; Stempin, J.L.; Wexell, D.R.

    1996-11-01

    Lead acid cells assembled with extruded separators displayed relatively uniform capacity and voltage parameters through 100{sup +} cycles of charge/discharge. This contrasts to failure of control cells with glass mat separators after 60 cycles. The mullite/alumina separators with 50, 60, and 70% porosity separators appear suitable for both flooded and sealed lead acid cell applications. The advantages of the rigid ceramic separators over fiber mat materials are in the uniformity of capacity and voltage, the ease of cell assembly, and the probability that firm stacking pressure on the active material will yield greater cycle life, especially at elevated temperatures.

  17. 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.

  18. 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.

  19. 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.

  20. Rigidity and Smoothness of Motion.

    DTIC Science & Technology

    1987-11-01

    N-AMP 555 RIGIDITY NAM SMOOTNNESS OF NOTION(U) HNSSRCNUJSETTS INST in1 OF TECH CAMRIDE ARTIFICIAL INTELLIGENCE LN S ULA ET AL. NOV 67 RI-M-909 NSSR4...8217.* .% , ./_ %_I MASSACIHUSETTS INSTITUTE OF TECHNOLOGY ARIIl"I(’IAL ITELlIGENCE LABORATOtRY Lr) A.. .Me mo 9,0,9. November, 19S7UI) ;1TI CD.’ ELU...Artificid Intelligenco Labo- ratory of the Massachusotts In.,titute of lchnolo -. 1upport fi r the lab- oratorys artificial intelligence ro.-oarch i

  1. Redundant causation from a sufficient cause perspective.

    PubMed

    Gatto, Nicolle M; Campbell, Ulka B

    2010-08-02

    Sufficient causes of disease are redundant when an individual acquires the components of two or more sufficient causes. In this circumstance, the individual still would have become diseased even if one of the sufficient causes had not been acquired. In the context of a study, when any individuals acquire components of more than one sufficient cause over the observation period, the etiologic effect of the exposure (defined as the absolute or relative difference between the proportion of the exposed who develop the disease by the end of the study period and the proportion of those individuals who would have developed the disease at the moment they did even in the absence of the exposure) may be underestimated. Even in the absence of confounding and bias, the observed effect estimate represents only a subset of the etiologic effect. This underestimation occurs regardless of the measure of effect used.To some extent, redundancy of sufficient causes is always present, and under some circumstances, it may make a true cause of disease appear to be not causal. This problem is particularly relevant when the researcher's goal is to characterize the universe of sufficient causes of the disease, identify risk factors for targeted interventions, or construct causal diagrams. In this paper, we use the sufficient component cause model and the disease response type framework to show how redundant causation arises and the factors that determine the extent of its impact on epidemiologic effect measures.

  2. Experimental test of induced rigidity

    NASA Astrophysics Data System (ADS)

    Fincher, Curtis R.; Gochanour, Craig R.

    1987-02-01

    Recent theoretical models for the nematic phase of semiflexible polymer chains predict a strong coupling between order and the conformational degrees of freedom of the chain. The presence of order in the nematic phase results in a strong preference for linear or rod-like conformations over flexible, random coil conformations. This conformational selection or induced rigidity is predicted to be general phenomenon associated with semiflexible chains. We have tested these predictions using a soluble polydiacetylene (4BCMU) as a probe. The 4BCMU chain undergoes a conformational transition (rod-coil) as a function of temperature in toluene which is accompanied by a large change in optical properties allowing the conformational transition to be followed spectroscopically in extremely dilute solutions. 4BCMU is miscible with both isotropic and nematic solutions of poly-(n-hexyl isocyanate) in toluene. If current models of induced rigidity are accurate, there should be a large shift in the transition temperature for the 4BCMU transition in nematic poly-(n-hexyl isocyanate) solutions. Experimentally we find no shift in the transition for nematic solutions when compared to dilute isotropic solutions. Possible explanations for the discrepancy between theory and experiment are discussed.

  3. Small Moving Rigid Body into a Viscous Incompressible Fluid

    NASA Astrophysics Data System (ADS)

    Lacave, Christophe; Takahashi, Takéo

    2017-03-01

    We consider a single disk moving under the influence of a two dimensional viscous fluid and we study the asymptotic as the size of the solid tends to zero. If the density of the solid is independent of ɛ, the energy equality is not sufficient to obtain a uniform estimate for the solid velocity. This will be achieved thanks to the optimal L p - L q decay estimates of the semigroup associated to the fluid-rigid body system and to a fixed point argument. Next, we will deduce the convergence to the solution of the Navier-Stokes equations in R2.

  4. Energy self-sufficiency for Hawaii

    SciTech Connect

    Shupe, J.W.

    1982-06-11

    Currently, Hawaii is almost totally dependent for energy on imported oil. The island state has a wide variety of renewable energy resources, however, and for the past decade has supported the development of these resources as substitutes for seaborne petroleum. Sufficient progress has been made to date in commercializing a number of these alternative energy sources to give cause for optimism that Hawaii will be able to achieve energy self-sufficiency with its indigenous renewable resources.

  5. The rigid Horowitz-Myers conjecture

    NASA Astrophysics Data System (ADS)

    Woolgar, Eric

    2017-03-01

    The new positive energy conjecture was first formulated by Horowitz and Myers in the late 1990s to probe for a possible extended, nonsupersymmetric AdS/CFT correspondence. We consider a version formulated for complete, asymptotically Poincaré-Einstein Riemannian metrics ( M, g) with bounded scalar curvature R ≥ - n( n - 1) and with no (inner) boundary except possibly a finite union of compact, totally geodesic hypersurfaces (horizons). This version then asserts that any such ( M, g) must have mass not less than a certain bound which is realized as the mass m 0 of a metric g 0 induced on a time-symmetric slice of a spacetime called an AdS soliton. This conjecture remains unproved, having so far resisted standard techniques. Little is known other than that the conjecture is true for metrics which are sufficiently small perturbations of g 0. We pose another test for the conjecture. We assume its validity and attempt to prove as a corollary the corresponding scalar curvature rigidity statement, which is that g 0 is the unique asymptotically Poincaré-Einstein metric with mass m 0 obeying R ≥ - n( n - 1). Were a second such metric g 1 not isometric to g 0 to exist, it then may well admit perturbations of lower mass, contradicting the assumed validity of the conjecture. We find enough rigidity to show that the minimum mass metric must be static Einstein, so the problem is reduced to that of static uniqueness. When n = 3 the manifold must be isometric to a time-symmetric slice of an AdS soliton spacetime, or must have a non-compact horizon. En route we study the mass aspect, obtaining and generalizing known results: (i) we relate the mass aspect of static metrics to the holographic energy density, (ii) we obtain the conformal invariance of the mass aspect when the bulk dimension is odd, and (iii) we show the vanishing of the mass aspect for negative Einstein manifolds with Einstein conformal boundary.

  6. 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.

  7. Unbiased rigid registration using transfer functions

    NASA Astrophysics Data System (ADS)

    Hahn, Dieter A.; Hornegger, Joachim; Bautz, Werner; Kuwert, Torsten; Roemer, Wolfgang

    2005-04-01

    The evaluation of tumor growth as regression under therapy is an important clinical issue. Rigid registration of sequentially acquired 3D-images has proven its value for this purpose. Existing approaches to rigid image registration use the whole volume for the estimation of the rigid transform. Non-rigid soft tissue deformation, however, will imply a bias to the registration result, because local deformations cannot be modeled by rigid transforms. Anatomical substructures, like bones or teeth, are not affected by these deformations, but follow a rigid transform. This important observation is incorporated in the proposed registration algorithm. The selection of anatomical substructure is done by manual interaction of medical experts adjusting the transfer function of the volume rendering software. The parameters of the transfer function are used to identify the voxels that are considered for registration. A rigid transform is estimated by a quaternion gradient descent algorithm based on the intensity values of the specified tissue classes. Commonly used voxel intensity measures are adjusted to the modified registration algorithm. The contribution describes the mathematical framework of the proposed registration method and its implementation in a commercial software package. The experimental evaluation includes the discussion of different similarity measures, the comparison of the proposed method to established rigid registration techniques and the evaluation of the efficiency of the new method. We conclude with the discussion of potential medical applications of the proposed registration algorithm.

  8. The Personality Characteristics of the Rigid Learner.

    ERIC Educational Resources Information Center

    Dean, Raymond S.; Garabedian, A. Alexander

    1981-01-01

    Investigated personality dimensions concomitant with learner's cognitive rigidity. Results indicated the personality dimensions of tenseness, compulsivity, group dependency, absent-mindedness, sensitivity, and emotional stability explained 36 percent of the variability in subjects' increasing levels of cognitive rigidity. Showed a pervasive use of…

  9. Weak rigidity in the PPN formalism

    SciTech Connect

    del Olmo, V.; Olivert, J.

    1987-04-01

    The influence of the concept of weakly rigid almost-thermodynamic material schemes on the classical deformations is analyzed. The methods of the PPN approximation are considered. In this formalism, the equations that characterize the weak rigidity are expressed. As a consequence of that, an increase of two orders of magnitude in the strain rate tensor is obtained.

  10. Rigid fibrous ceramics for entry systems

    NASA Technical Reports Server (NTRS)

    Banas, Ronald P.

    1993-01-01

    The topics addressed are: (1) high payoff areas with reusable surface insulation; (2) technology opportunities/gap; (3) coatings for rigid fibrous ceramics; (4) challenges for reusable rigid fibrous ceramics - Lunar/Mars aerobraking heatshield; (5) comparison of LI-900 and HTP properties; and (6) comparison of microstructures.

  11. 21 CFR 868.5540 - Rigid laryngoscope.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid laryngoscope. 868.5540 Section 868.5540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5540 Rigid laryngoscope. (a) Identification....

  12. 21 CFR 868.5540 - Rigid laryngoscope.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rigid laryngoscope. 868.5540 Section 868.5540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5540 Rigid laryngoscope. (a) Identification. A...

  13. 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....

  14. 21 CFR 882.1020 - Rigidity analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 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....

  15. 21 CFR 882.1020 - Rigidity analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 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....

  16. 21 CFR 882.1020 - Rigidity analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 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....

  17. 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....

  18. Sufficient criterion for separability of bipartite states

    SciTech Connect

    Ha, Kil-Chan

    2010-07-15

    We observe a convex subset of the set of all M x N separable states. On the basis of this observation, we give an alternative sufficient condition for separability of bipartite states. This criterion gives rise to a family of quantum channels which are entanglement breaking.

  19. Energy self-sufficiency for the UK

    SciTech Connect

    Cornell, M.; Belgrave, R.

    1985-01-01

    This book calls for more public debate about the criteria against which government and state industries take decisions on energy matters. It argues that there is a case for seeking to maintain levels of between 50% and 80% self sufficiency in energy.

  20. Professional Development for Professionals: Beyond Sufficiency Learning

    ERIC Educational Resources Information Center

    Murphy, Gerald A.; Calway, Bruce A.

    2008-01-01

    We question the current role of professional associations in developing a culture of learning beyond a sufficiency or competency level. This brings into question the underlying philosophy of Professional Standards legislation. This legislation mandates continuing professional development for professionals without stating what should be achieved…

  1. Behavioral Interventions to Advance Self-Sufficiency

    ERIC Educational Resources Information Center

    MDRC, 2017

    2017-01-01

    As the first major effort to use a behavioral economics lens to examine human services programs that serve poor and vulnerable families in the United States, the Behavioral Interventions to Advance Self-Sufficiency (BIAS) project demonstrated the value of applying behavioral insights to improve the efficacy of human services programs. The BIAS…

  2. ON A SUFFICIENT CONDITION FOR ABSOLUTE CONTINUITY.

    DTIC Science & Technology

    The formulation of a condition which yields absolute continuity when combined with continuity and bounded variation is the problem considered in the...Briefly, the formulation is achieved through a discussion which develops a proof by contradiction of a sufficiently theorem for absolute continuity which uses in its hypothesis the condition of continuity and bounded variation .

  3. 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.

  4. Are better conductors more rigid?

    NASA Astrophysics Data System (ADS)

    Eom, Young-Ho; Jeong, Hawoong; Orland, Henri; Yi, Juyeon

    2006-10-01

    The variation of the bending stiffness of various materials is studied from the point of view of the electronic band characteristics. As far as the electronically generated bending stiffness κe (which we refer to as electro-stiffness) is concerned, the relevant factors are the orbital overlap t, the gap width u between the valence band and the conduction band, and the electron filling fraction γ. A perturbative calculation leads to the approximate expression κe ~ t2/√u2 + t2. This shows that materials with a large overlap and narrow band gap should be stiffer. The electro-stiffness also depends on the electron filling-fraction. We find that κe(γ) <= κe(1/2). These kinds of behavior are confirmed by numerical calculations. In addition, we study the variation in the projected length of flexible molecules under a voltage bias. The nonlinear variation of the bending rigidity is shown to give rise to a length contraction or dilation, depending on the voltage bias.

  5. Aggregation dynamics of rigid polyelectrolytes

    NASA Astrophysics Data System (ADS)

    Tom, Anvy Moly; Rajesh, R.; Vemparala, Satyavani

    2016-01-01

    Similarly charged polyelectrolytes are known to attract each other and aggregate into bundles when the charge density of the polymers exceeds a critical value that depends on the valency of the counterions. The dynamics of aggregation of such rigid polyelectrolytes are studied using large scale molecular dynamics simulations. We find that the morphology of the aggregates depends on the value of the charge density of the polymers. For values close to the critical value, the shape of the aggregates is cylindrical with height equal to the length of a single polyelectrolyte chain. However, for larger values of charge, the linear extent of the aggregates increases as more and more polymers aggregate. In both the cases, we show that the number of aggregates decrease with time as power laws with exponents that are not numerically distinguishable from each other and are independent of charge density of the polymers, valency of the counterions, density, and length of the polyelectrolyte chain. We model the aggregation dynamics using the Smoluchowski coagulation equation with kernels determined from the molecular dynamics simulations and justify the numerically obtained value of the exponent. Our results suggest that once counterions condense, effective interactions between polyelectrolyte chains short-ranged and the aggregation of polyelectrolytes are diffusion-limited.

  6. 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

  7. 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

  8. [Vitamin sufficiency of young basketball players].

    PubMed

    Vrzhesinskaia, O A; Pereverzeva, O G; Beketova, N A; Isaeva, V A; Kharitonchik, L A; Kodentsova, V M; Martinchik, A N; Baturin, A K

    2004-01-01

    The investigation of vitamin sufficiency of young basket-ball players 14-16 years old (17 girls and 14 boys) has been carried out 59-77 per cent of the children had the deficiency of B group vitamins, 24-54 per cent--vitamin E insufficiency, most of them (82-100 per cent)--deficit of carotenoids while they were sufficiently vitamins C and A supplied. The girls were supplied with vitamins better than boys. There was no one adequately supplied with all vitamins among boys while 12 per cent of girls had adequately sufficiency. The girls had deficit of 1-2 vitamins more often whereas the combined insufficiency of 3-4 vitamins took place in 1.8-2.3 fold more frequently among boys. Daily intake of multivitamin containing 10 vitamins in daily recommended doses, lipoic acid, methionin and 9 minerals by boys lead to their blood plasma vitamin C, E, B-2 and beta-carotene level increase. Vitamin C insufficiency disappeared. Deficit of beta-carotene and vitamin B-6 became 1.5 fold rarely, vitamin B-2--2 fold, vitamin E--6 fold. Thus daily intake of recommended doses of vitamins eliminates biochemical signs of vitamin deficiency.

  9. Pharmacological targeting of membrane rigidity: implications on cancer cell migration and invasion

    NASA Astrophysics Data System (ADS)

    Braig, Simone; Schmidt, B. U. Sebastian; Stoiber, Katharina; Händel, Chris; Möhn, Till; Werz, Oliver; Müller, Rolf; Zahler, Stefan; Koeberle, Andreas; Käs, Josef A.; Vollmar, Angelika M.

    2015-08-01

    The invasive potential of cancer cells strongly depends on cellular stiffness, a physical quantity that is not only regulated by the mechanical impact of the cytoskeleton but also influenced by the membrane rigidity. To analyze the specific role of membrane rigidity in cancer progression, we treated cancer cells with the Acetyl-CoA carboxylase inhibitor Soraphen A and revealed an alteration of the phospholipidome via mass spectrometry. Migration, invasion, and cell death assays were employed to relate this alteration to functional consequences, and a decrease of migration and invasion without significant impact on cell death has been recorded. Fourier fluctuation analysis of giant plasma membrane vesicles showed that Soraphen A increases membrane rigidity of carcinoma cell membranes. Mechanical measurements of the creep deformation response of whole intact cells were performed using the optical stretcher. The increase in membrane rigidity was observed in one cell line without changing the creep deformation response indicating no restructuring of the cytoskeleton. These data indicate that the increase of membrane rigidity alone is sufficient to inhibit invasiveness of cancer cells, thus disclosing the eminent role of membrane rigidity in migratory processes.

  10. Some pathophysiological aspects of the parkinsonian rigidity.

    PubMed

    Delwaide, P J; Sabbatino, M; Delwaide, C

    1986-01-01

    The neurophysiological mechanisms explaining parkinsonian rigidity are still poorly understood. Its reflex nature is well established but the peripheral afferents causing it are likely multiple and not restricted to IA afferents. Few modifications appear in spinal cord reflex mechanisms and are limited to some interneurones (reciprocal inhibition and flexor reflex). At present, the most plausible explanation of rigidity relies on hyperactivity in long loop reflex pathways relaying in the brain.

  11. 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.

  12. Metrology of Non-Rigid Objects

    SciTech Connect

    Blaedel, K L; Smith, D W; Claudet, A A; Kasper, E P; Patterson, S R

    2002-01-01

    Dimensional characterization of non-rigid parts presents many challenges. For example, when a non-rigid part is mounted in an inspection apparatus the effects of fixturing constraints cause significant deformation of the part. If the part is not used in normal service with the same load conditions as during inspection, the dimensional characteristics in service will deviate from the reported values during inspection. Further, the solution of designing specialized fixturing to duplicate ''as-installed'' conditions does not fully resolve the problem because each inspection requires its own methodology. The goal of this project is to formulate the research problem and propose a method of assessing the dimensional characteristics of non-rigid parts. The measured dimension of a rigid component is traceable at some level of confidence to a single source (NIST in the USA). Hence the measurement of one component of an assembly can be related to the measurement of another component of that assembly. There is no generalized analog to this pedigreed process for dimensionally characterizing non-rigid bodies. For example, a measurement made on a sheet-metal automobile fender is heavily influenced by how it is held during the measurement making it difficult to determine how well that fender will assemble to the rest of the (non-rigid) car body. This problem is often overcome for specific manufacturing problems by constructing rigid fixtures that over-constrain the non-rigid parts to be assembled and then performing the dimensional measurement of the contour of each component to check whether each meets specification. Note that such inspection measurements will yield only an approximation to the assembled shape, which is a function of both the geometry and the compliance of the component parts of the assembly. As a result, non-rigid components are more difficult to specify and inspect and therefore are more difficult to purchase from outside vendors compared to rigid components

  13. Metrology of Non-Rigid Objects

    SciTech Connect

    Blaedel, K; Swift, D; Claudet, A; Kasper, E; Patterson, S

    2002-01-01

    Dimensional characterization of non-rigid parts presents many challenges. For example, when a non-rigid part is mounted in an inspection apparatus the effects of fixturing constraints are significant. If the part is not used in normal service with the same load conditions as during inspection, the dimensional characteristics will deviate from reported values. Further, the solution of designing specialized fixturing to duplicate ''as-installed'' conditions does not fully resolve the problem because each inspection requires its own methodology. The goal of this project is to formulate the research problem and propose a method of assessing the dimensional characteristics of non-rigid parts. The measured dimension of a rigid component is traceable at some level of confidence to a single source (NIST in the USA). Hence the measurement of one component of an assembly can be related to the measurement of another component of that assembly. There is no generalized analog to this pedigreed process for dimensionally characterizing non-rigid bodies. For example, a measurement made on a sheet-metal automobile fender is heavily influenced by how it is held during the measurement making it difficult to determine how well that fender will assemble to the rest of the (non-rigid) car body. This problem is often overcome for specific manufacturing problems by constructing rigid fixtures that over-constrain the non-rigid parts to be assembled and then performing the dimensional measurement of the contour of each component to check whether each meets specification. Note that such inspection measurements will yield only an approximation to the assembled shape, which is a function of both the geometry and the compliance of the component parts of the assembly. As a result, non-rigid components are more difficult to specify and inspect and therefore are more difficult to purchase from outside vendors compared to rigid components. The problems are compounded as the requirements come to

  14. Nonmagnetic rigid and flexible outer sheath with pneumatic interlocking mechanism for minimally invasive surgical approach.

    PubMed

    Yamashita, Hiromasa; Zuo, Siyang; Masamune, Ken; Liao, Hongen; Dohi, Takeyoshi

    2009-01-01

    We developed a nonmagnetic rigid and flexible outer sheath with pneumatic interlocking mechanism using flexible toothed links and a wire-driven bending distal end. The outer sheath can be switched between rigid and flexible modes easily depending on surgical scenes, and the angle of its distal end can be controlled by three nylon wires. All components of flexible parts are made of MRI-compatible nonmagnetic plastics. We manufactured the device with 300-mm long, 16-mm outer diameter, 7-mm inner diameter and 90-mm bending distal end. Holding power of the device in rigid mode was maximum 3.6 N, which was sufficient for surgical tasks in body cavity. In vivo experiment using a swine, our device performed smooth insertion of a flexible endoscope and a biopsy forceps into reverse side of the liver, intestines and spleen with a curved path. In conclusion, our device shows availability of secure approach of surgical instruments into deep cavity.

  15. Rigidity Dependence of Cosmic Ray Modulation

    NASA Astrophysics Data System (ADS)

    Agarwal Mishra, Rekha; Mishra, Rajesh Kumar

    2012-07-01

    The various observed harmonics of the cosmic ray variation may be understood on a unified basis if the free space cosmic ray anisotropy is non-sinusoidal in form. The major objective of this paper is to study the first three harmonics of cosmic ray intensity on geo-magnetically quiet days over the period 1965-1990 for Deep River, Goose Bay and Tokyo neutron monitoring stations. The amplitude of first harmonic remains high for Deep River having low cutoff rigidity as compared to Tokyo neutron monitor having high cutoff rigidity on quiet days. The diurnal amplitude significantly decreases in 1987 at Deep River and in 1986 at Tokyo during solar activity minimum years. The diurnal time of maximum significantly shifts to an earlier time as compared to the corotational direction at both the stations having different cutoff rigidities. The time of maximum for first harmonic significantly shifts towards later hours and for second harmonic it shifts towards earlier hours at low cutoff rigidity station i.e. Deep River as compared to the high cut off rigidity station i.e. Tokyo on quiet days. The amplitude of second/third harmonics shows a good positive correlation with solar wind velocity, while the others (i.e. amplitude and phase) have no significant correlation on quiet days. The solar wind velocity significantly remains in the range 350 to 425 km/s i.e. being nearly average on quiet days. The amplitude and direction of the anisotropy on quiet days are weakly dependent on high-speed solar wind streams for these neutron monitoring stations of low and high cutoff rigidity threshold. Keywords: cosmic ray, cut off rigidity, quiet days, harmonics.

  16. Patient comfort during flexible and rigid cystourethroscopy

    PubMed Central

    Zdrojowy, Romuald; Wojciechowska, Joanna; Kościelska, Katarzyna; Dembowski, Janusz; Matuszewski, Michał; Tupikowski, Krzysztof; Małkiewicz, Bartosz; Kołodziej, Anna

    2016-01-01

    Introduction Cystourethroscopy (CS) is an endoscopic method used to visualize the urethra and the bladder. Aim In this study, we prospectively evaluated pain in men undergoing cyclic cystoscopic assessment with rigid and flexible instruments after transurethral resection of bladder tumor (TURB). Material and methods One hundred and twenty male patients who were under surveillance after a TURB procedure due to urothelial cell carcinoma and who had undergone at least one rigid cystourethroscopy in the past were enrolled in the trial. Patients were prospectively randomized to age-matched groups for flexible (group F) or rigid (group R) CS. Patient's comfort was evaluated on an 11-grade scale, ranging from 0 (free from pain) to 10 points (unbearable pain). Results The patients described the pain during the previous rigid CS as ranging from 4 to 10 (mean: 6.8) in group F and from 0 to 10 (mean: 5.8) in group R. Group R patients described the pain during the current rigid CS as ranging from 0 to 10 (mean: 5.7). No mean change in the grade was observed between the two pain descriptions (no change 11 patients, weaker pain 25 patients, stronger pain 24 patients, gamma 0.51, p < 0.0001). Group F described the pain as 1 to 5 (mean: 2.1). In the case of flexible CS the pain experience was greatly lowered compared to the previous rigid CS. All flexible CS patients reported lowered pain (by 1 to 9 grades). Patients’ age did not influence the comfort of the flexible CS or the change in pain level. Conclusions Flexible CS is better tolerated than rigid cystoscopy by male patients regardless of patients’ age. PMID:27458489

  17. Patient comfort during flexible and rigid cystourethroscopy.

    PubMed

    Krajewski, Wojciech; Zdrojowy, Romuald; Wojciechowska, Joanna; Kościelska, Katarzyna; Dembowski, Janusz; Matuszewski, Michał; Tupikowski, Krzysztof; Małkiewicz, Bartosz; Kołodziej, Anna

    2016-01-01

    Cystourethroscopy (CS) is an endoscopic method used to visualize the urethra and the bladder. In this study, we prospectively evaluated pain in men undergoing cyclic cystoscopic assessment with rigid and flexible instruments after transurethral resection of bladder tumor (TURB). One hundred and twenty male patients who were under surveillance after a TURB procedure due to urothelial cell carcinoma and who had undergone at least one rigid cystourethroscopy in the past were enrolled in the trial. Patients were prospectively randomized to age-matched groups for flexible (group F) or rigid (group R) CS. Patient's comfort was evaluated on an 11-grade scale, ranging from 0 (free from pain) to 10 points (unbearable pain). The patients described the pain during the previous rigid CS as ranging from 4 to 10 (mean: 6.8) in group F and from 0 to 10 (mean: 5.8) in group R. Group R patients described the pain during the current rigid CS as ranging from 0 to 10 (mean: 5.7). No mean change in the grade was observed between the two pain descriptions (no change 11 patients, weaker pain 25 patients, stronger pain 24 patients, gamma 0.51, p < 0.0001). Group F described the pain as 1 to 5 (mean: 2.1). In the case of flexible CS the pain experience was greatly lowered compared to the previous rigid CS. All flexible CS patients reported lowered pain (by 1 to 9 grades). Patients' age did not influence the comfort of the flexible CS or the change in pain level. Flexible CS is better tolerated than rigid cystoscopy by male patients regardless of patients' age.

  18. 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).

  19. 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...

  20. 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...

  1. 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...

  2. 21 CFR 876.3630 - Penile rigidity implant.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Penile rigidity implant. 876.3630 Section 876.3630...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Prosthetic Devices § 876.3630 Penile rigidity implant. (a) Identification. A penile rigidity implant is a device that consists of a pair of semi-rigid rods implanted in the...

  3. 21 CFR 876.3630 - Penile rigidity implant.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Penile rigidity implant. 876.3630 Section 876.3630...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Prosthetic Devices § 876.3630 Penile rigidity implant. (a) Identification. A penile rigidity implant is a device that consists of a pair of semi-rigid rods implanted in the...

  4. 21 CFR 876.3630 - Penile rigidity implant.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Penile rigidity implant. 876.3630 Section 876.3630...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Prosthetic Devices § 876.3630 Penile rigidity implant. (a) Identification. A penile rigidity implant is a device that consists of a pair of semi-rigid rods implanted in the...

  5. Crystal structure prediction of rigid molecules.

    PubMed

    Elking, Dennis M; Fusti-Molnar, Laszlo; Nichols, Anthony

    2016-08-01

    A non-polarizable force field based on atomic multipoles fit to reproduce experimental crystal properties and ab initio gas-phase dimers is described. The Ewald method is used to calculate both long-range electrostatic and 1/r(6) dispersion energies of crystals. The dispersion energy of a crystal calculated by a cutoff method is shown to converge slowly to the exact Ewald result. A method for constraining space-group symmetry during unit-cell optimization is derived. Results for locally optimizing 4427 unit cells including volume, cell parameters, unit-cell r.m.s.d. and CPU timings are given for both flexible and rigid molecule optimization. An algorithm for randomly generating rigid molecule crystals is described. Using the correct experimentally determined space group, the average and maximum number of random crystals needed to find the correct experimental structure is given for 2440 rigid single component crystals. The force field energy rank of the correct experimental structure is presented for the same set of 2440 rigid single component crystals assuming the correct space group. A complete crystal prediction is performed for two rigid molecules by searching over the 32 most probable space groups.

  6. Rigidity loss in disordered network materials

    NASA Astrophysics Data System (ADS)

    Ellenbroek, Wouter G.; Hagh, Varda F.; Kumar, Avishek; Thorpe, M. F.; van Hecke, Martin

    Weakly jammed sphere packings show a very peculiar elasticity, with a ratio of compression modulus to shear modulus that diverges as the number of contacts approaches the minimum required for rigidity. Creating artificial isotropic network materials with this property is a challenge: so far, the least elaborate way to generate them is to actually simulate weakly compressed repulsive spheres. The next steps in designing such networks hinge upon a solid understanding of what properties of the sphere-packing derived network are essential for its elasticity. We elucidate the topological aspects of this question by comparing the rigidity transition in these networks to that in other random spring network models, including the common bond-diluted triangular net and a self-stress-free variant of that. We use the pebble game algorithm for identifying rigid clusters in mechanical networks to demonstrate that the marginally rigid state in sphere packings is perfectly isostatic everywhere, and the addition or removal of a single bond creates a globally stressed or globally floppy network, respectively. By contrast, the other classes of random network random networks show a more localized response to addition and removal of bonds, and, correspondingly, a more gradual rigidity transition.

  7. Sufficient symmetry conditions for Topological Quantum Order.

    PubMed

    Nussinov, Zohar; Ortiz, Gerardo

    2009-10-06

    We prove sufficient conditions for Topological Quantum Order at zero and finite temperatures. The crux of the proof hinges on the existence of low-dimensional Gauge-Like Symmetries, thus providing a unifying framework based on a symmetry principle. These symmetries may be actual invariances of the system, or may emerge in the low-energy sector. Prominent examples of Topological Quantum Order display Gauge-Like Symmetries. New systems exhibiting such symmetries include Hamiltonians depicting orbital-dependent spin exchange and Jahn-Teller effects in transition metal orbital compounds, short-range frustrated Klein spin models, and p+ip superconducting arrays. We analyze the physical consequences of Gauge-Like Symmetries (including topological terms and charges) and show the insufficiency of the energy spectrum, topological entanglement entropy, maximal string correlators, and fractionalization in establishing Topological Quantum Order. General symmetry considerations illustrate that not withstanding spectral gaps, thermal fluctuations may impose restrictions on suggested quantum computing schemes. Our results allow us to go beyond standard topological field theories and engineer systems with Topological Quantum Order.

  8. Sufficient trial size to inform clinical practice

    PubMed Central

    Manski, Charles F.; Tetenov, Aleksey

    2016-01-01

    Medical research has evolved conventions for choosing sample size in randomized clinical trials that rest on the theory of hypothesis testing. Bayesian statisticians have argued that trials should be designed to maximize subjective expected utility in settings of clinical interest. This perspective is compelling given a credible prior distribution on treatment response, but there is rarely consensus on what the subjective prior beliefs should be. We use Wald’s frequentist statistical decision theory to study design of trials under ambiguity. We show that ε-optimal rules exist when trials have large enough sample size. An ε-optimal rule has expected welfare within ε of the welfare of the best treatment in every state of nature. Equivalently, it has maximum regret no larger than ε. We consider trials that draw predetermined numbers of subjects at random within groups stratified by covariates and treatments. We report exact results for the special case of two treatments and binary outcomes. We give simple sufficient conditions on sample sizes that ensure existence of ε-optimal treatment rules when there are multiple treatments and outcomes are bounded. These conditions are obtained by application of Hoeffding large deviations inequalities to evaluate the performance of empirical success rules. PMID:27601679

  9. Generic Rigidity for Circle Diffeomorphisms with Breaks

    NASA Astrophysics Data System (ADS)

    Kocić, Saša

    2016-06-01

    We prove that {C^r}-smooth ({r > 2}) circle diffeomorphisms with a break, i.e., circle diffeomorphisms with a single singular point where the derivative has a jump discontinuity, are generically, i.e., for almost all irrational rotation numbers, not {C^{1+\\varepsilon}}-rigid, for any {\\varepsilon > 0}. This result complements our recent proof, joint with Khanin (Geom Funct Anal 24:2002-2028, 2014), that such maps are generically {C^1}-rigid. It stands in remarkable contrast to the result of Yoccoz (Ann Sci Ec Norm Sup 17:333-361, 1984) that {C^r}-smooth circle diffeomorphisms are generically {C^{r-1-κ}}-rigid, for any {κ > 0}.

  10. Quantum mechanics of a generalised rigid body

    NASA Astrophysics Data System (ADS)

    Gripaios, Ben; Sutherland, Dave

    2016-05-01

    We consider the quantum version of Arnold’s generalisation of a rigid body in classical mechanics. Thus, we quantise the motion on an arbitrary Lie group manifold of a particle whose classical trajectories correspond to the geodesics of any one-sided-invariant metric. We show how the derivation of the spectrum of energy eigenstates can be simplified by making use of automorphisms of the Lie algebra and (for groups of type I) by methods of harmonic analysis. We show how the method can be extended to cosets, generalising the linear rigid rotor. As examples, we consider all connected and simply connected Lie groups up to dimension 3. This includes the universal cover of the archetypical rigid body, along with a number of new exactly solvable models. We also discuss a possible application to the topical problem of quantising a perfect fluid.

  11. 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.

  12. Rigid occlusive titanium barriers for alveolar bone augmentation: two reports with 24-month follow-up

    PubMed Central

    Engelke, Wilfried; Deccó, Oscar; Cura, Andrea C; Borie, Eduardo; Beltrán, Víctor

    2014-01-01

    Titanium barriers have been used for guided bone regeneration in preclinical and preliminary clinical reports as a possible alternative to bone grafting. In two cases with lateral bone defects, rigid titanium barriers were used to provide a secluded space in conjunction with bone substitutes. Sufficient lateral bone volume was generated for implant placement, and no complications were observed during 2 years of follow up. In conclusion, space-making stiff titanium barriers may be applied successfully for lateral alveolar crest augmentation. PMID:24955200

  13. 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.

  14. Rigid spine syndrome and fatal cardiomyopathy.

    PubMed Central

    Colver, A F; Steer, C R; Godman, M J; Uttley, W S

    1981-01-01

    A 7 1/2-year-old girl had the clinical features of the rigid spine syndrome of Dubowitz. Muscle biopsy showed a predominance of type 2 fibres with neither myopathic features nor an increase in connective tissue. In addition, she had a hypertrophic cardiomyopathy with which she presented in heart failure and from which she died suddenly one month later. The association of rigid spine syndrome with cardiomyopathy has not been reported previously. Images Fig. 1 Fig. 2 Fig. 3 PMID:7193439

  15. Kinematic problem of rigid body orientation control

    NASA Astrophysics Data System (ADS)

    Plotnikov, P. K.; Sergeev, A. N.; Chelnokov, Iu. N.

    1991-10-01

    The problem of reducing a coordinate system linked with a rigid body to a reference coordinate system rotating with a specified (programmed) angular velocity is analyzed using a kinematic formulation. The mathematic model of motion includes kinematic equations of the angular motion of a rigid body in nonnormalized quaternions; used as the controls are projections of the absolute angular velocity of body rotation to the coordinate axes. Two kinds of correction are proposed which represent quaternion analogs of the positional and integral corrections. Linear error equations for the orientation control system are obtained for the types of correction proposed here.

  16. On Saturnian cosmic ray cutoff rigidities

    NASA Astrophysics Data System (ADS)

    Sauer, H. H.

    1980-03-01

    It has been determined that Saturn possesses a relatively pure dipolar magnetic field through magnetometer measurements made by Ness et al. (1979, private comm.) and Smith et al. (1979). The paper briefly outlines the dipole geomagnetic cutoff theory and demonstrates the scaling required for its applicability to energetic particle measurements in the vicinity of Saturn. Since the cutoff rigidity is a function of viewing direction, the effective cutoff rigidity must be determined as an integration over the finite viewing angle of a physical detector.

  17. Rigid and semi rigid polyurethane resins: A structural investigation using DMA, SAXS and Le Bail method

    NASA Astrophysics Data System (ADS)

    Trovati, Graziella; Sanches, Edgar A.; de Souza, Sérgio M.; dos Santos, Amanda L.; Neto, Salvador C.; Mascarenhas, Yvonne P.; Chierice, Gilberto O.

    2014-10-01

    Two different types of polyurethane (PU) resins were synthesized with pre-polymer/polyol (-NCO/-OH) mass proportions of 1:1 (Rigid PU) and 1:1.5 (Semi rigid PU). Based on the results from Dynamic Mechanical Analysis (DMA), rigid PU showed a higher Storage Modulus (E‧) which may be related to the macromolecules crosslinking process. In contrast, the greater Loss Modulus (E″) in semi rigid PU was related to the greater ability to dissipate energy, suggesting that the change in polyol/pre-polymer ratio promotes structural changes in PU resins. Le Bail method was performed with a triclinic crystal structure (for rigid PU, a = 4.9117 (2) Å, b = 8.1103 (2) Å, c = 19.7224 (2) Å, α = 116.2831 (2)°, β = 125.4058 (2)° and γ = 83.6960 (2)°). Average crystallite size was found in the range of 26 (1) Å for rigid PU and somewhat smaller around 20 (1) Å for semi rigid PU. The Guinier radii of gyration (Rg) and the maximum particle sizes (Dmax) were calculated based on Small Angle X-ray Scattering (SAXS) curves. Two different values for Radii of gyration (Rg) were calculated, one obtained from Guinier’s plot using the program Microcal Origin 7.5 (RgORIGIN) and other from the pair-distance distribution function (p(r)) calculation, using the GNOM (RgGNOM) program package The possible highest values of (RgORIGIN) were obtained from Guinier’s curves. For rigid and semi rigid PU resins, the (RgORIGIN) values were, respectively, (320 ± 1) and (260 ± 1) Å. The average radii of gyration (RgGNOM) were obtained from the calculated pair-distance distribution function (p(r)). For rigid and semi rigid PU resins, the RgGNOM values were, respectively, (95 ± 1) Å and (86 ± 1) Å. Dmax values were obtained from the p(r) and ranged from (330 ± 3) Å to (260 ± 3) Å for rigid and semi rigid PU, respectively. Kratky curves showed that less organized systems were produced when the polyol amount was increased.

  18. Energy Strategic Planning & Self-Sufficiency Project

    SciTech Connect

    Greg Retzlaff

    2005-03-30

    This report provides information regarding options available, their advantages and disadvantages, and the costs for pursuing activities to advance Smith River Rancheria toward an energy program that reduces their energy costs, allows greater self-sufficiency and stimulates economic development and employment opportunities within and around the reservation. The primary subjects addressed in this report are as follow: (1) Baseline Assessment of Current Energy Costs--An evaluation of the historical energy costs for Smith River was conducted to identify the costs for each component of their energy supply to better assess changes that can be considered for energy cost reductions. (2) Research Viable Energy Options--This includes a general description of many power generation technologies and identification of their relative costs, advantages and disadvantages. Through this research the generation technology options that are most suited for this application were identified. (3) Project Development Considerations--The basic steps and associated challenges of developing a generation project utilizing the selected technologies are identified and discussed. This included items like selling to third parties, wheeling, electrical interconnections, fuel supply, permitting, standby power, and transmission studies. (4) Energy Conservation--The myriad of federal, state and utility programs offered for low-income weatherization and utility bill payment assistance are identified, their qualification requirements discussed, and the subsequent benefits outlined. (5) Establishing an Energy Organization--The report includes a high level discussion of formation of a utility to serve the Tribal membership. The value or advantages of such action is discussed along with some of the challenges. (6) Training--Training opportunities available to the Tribal membership are identified.

  19. Multiple-Purpose Rigid Foam Insulation

    NASA Technical Reports Server (NTRS)

    Liu, Matthew T.

    1989-01-01

    Plastic foam promises to serve as multiple-purpose thermal insulation. Material is rigid, closed-cell, thermally stable foam or urethane-modified isocyanate. Made by reacting polyol mixture with polymeric diphenyl methane disocyanate in presence of catalyst and flurocarbon blowing agent. Properties customized for particular application by adjusting proportions of ingredients in polyol mixture.

  20. Flexible scaffolding made of rigid BARs.

    PubMed

    Frolov, Vadim A; Zimmerberg, Joshua

    2008-03-07

    Crescent-shaped BAR domains are generic actors in the creation of membrane curvature. In this issue, Frost et al. (2008) reveal how collective twisting of rigid F-BAR domains on a soft membrane surface may lead to different membrane curvatures.

  1. Adjustable Optical Mount Is More Rigid

    NASA Technical Reports Server (NTRS)

    Asbury, Bill G.; Coombs, David S.; Jones, Irby W.; Moore, Alvah S., Jr.

    1994-01-01

    Improved mount for lens or mirror in laser offers rigidity similar to that of nonadjustable optical mount. In comparison with older adjustable optical mounts, this one less susceptible to movements and distortions caused by vibrations and by thermal expansions and contractions. Mount contains neither adjustment rods (which grow or shrink as temperature varies) nor springs (which transmit vibrations to mounted optic).

  2. Plastic flow around rigid spherical inclusions

    NASA Technical Reports Server (NTRS)

    Ruoff, A. L.; Nelson, D. A., Jr.

    1974-01-01

    The extent of plastic flow in a spherical solid (assumed to be homogeneous and elastically and plastically isotropic), surrounding a concentric rigid sphere was calculated as a function of applied external pressure. The applied pressure necessary to cause plastic deformation throughout the solid was obtained.

  3. 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...

  4. Analysis and Modeling of Rigid Microswimmers

    NASA Astrophysics Data System (ADS)

    Meshkati, Farshad

    In this thesis, we investigate magnetically actuated rigid microswimmers based on analytical and numerical schemes. These swimming micro-robots have medical applications such as drug delivery and in vivo diagnostics. Our model employs the method of regularized Stokeslets to faithfully incorporate the low-Reynolds-number hydrodynamics of arbitrary rigid geometries. We show how these magnetized swimmers can be actuated and controlled by externally rotating uniform magnetic fields. Our model predicts the swimming characteristics such as speed and direction. We show how to determine the dynamic stability of steadily rotating microswimmers. First, we address what is the simplest geometry capable of swimming. We illustrate that, despite the common belief that rigid microswimmers need to be chiral to be able to cause propulsion, a simple achiral 3-bead geometry can exhibit appreciable propulsion and controllability. We generalize this to explain the minimum geometric requirements for rigid rotating propulsion based on a symmetry analysis. Next, we investigate the implications of the stability analysis on the control of the 3-bead swimmer. We show that by adjusting the angle between the magnetic field and its rotation, one can control the existence of multiple stable rotation modes, leading to control of swimming direction and speed.

  5. Quantification of the UPDRS Rigidity Scale.

    PubMed

    Patrick, S K; Denington, A A; Gauthier, M J; Gillard, D M; Prochazka, A

    2001-03-01

    In the clinical setting, parkinsonian rigidity is assessed using subjective rating scales such as that of the Unified Parkinson's Disease Rating System (UPDRS). However, such scales are susceptible to problems of sensitivity and reliability. Here, we evaluate the reliability and validity of a device designed to quantify parkinsonian rigidity at the elbow and the wrist. The method essentially quantifies the clinical examination and employs small sensors to monitor forces and angular displacements imposed by the clinician onto the limb segment distal to the joint being evaluated. Force and displacement data are used to calculate elastic and viscous stiffnesses and their vectorial sum, mechanical impedance. Interexaminer agreement of measures of mechanical impedance in subjects with Parkinson's disease was comparable to that of clinical UPDRS scores. Examiners tended to overrate rigidity on the UPDRS scale during reinforcement manoeuvres. Mechanical impedance was nonlinearly related to UPDRS ratings of rigidity at the elbow and wrist; characterization of such relationships allows interpretation of impedance measurements in terms of the clinical rating scales.

  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. Rigid rod anchored to infinite membrane.

    PubMed

    Guo, Kunkun; Qiu, Feng; Zhang, Hongdong; Yang, Yuliang

    2005-08-15

    We investigate the shape deformation of an infinite membrane anchored by a rigid rod. The density profile of the rod is calculated by the self-consistent-field theory and the shape of the membrane is predicted by the Helfrich membrane elasticity theory [W. Helfrich, Z. Naturforsch. 28c, 693 (1973)]. It is found that the membrane bends away from the rigid rod when the interaction between the rod and the membrane is repulsive or weakly attractive (adsorption). However, the pulled height of the membrane at first increases and then decreases with the increase of the adsorption strength. Compared to a Gaussian chain with the same length, the rigid rod covers much larger area of the membrane, whereas exerts less local entropic pressure on the membrane. An evident gap is found between the membrane and the rigid rod because the membrane's curvature has to be continuous. These behaviors are compared with that of the flexible-polymer-anchored membranes studied by previous Monte Carlo simulations and theoretical analysis. It is straightforward to extend this method to more complicated and real biological systems, such as infinite membrane/multiple chains, protein inclusion, or systems with phase separation.

  8. 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)

  9. 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...

  10. Geophysical Consequences of Icy Satellite Rigidity

    NASA Astrophysics Data System (ADS)

    Nimmo, Francis

    2006-09-01

    The interior structures of icy satellites are typically deduced by measuring J2 from flybys, and then using the hydrostatic assumption (i.e. zero rigidity) to deduce the polar moment of inertia. While this technique works well for the Earth, it fails dismally for Mars and the Moon. The recent detection of regional gravity anomalies on Ganymede [1] suggests loads supported by elastic stresses. Thus, the use of the hydrostatic assumption to derive structures for cold, icy bodies like Callisto [2] or Mimas should be treated with great caution [3]. The rigidity of icy satellites is important for at least three other reasons. Firstly, it controls (via the Love number k2) the degree of tidal heating experienced. For equal Love numbers, Enceladus and Europa would experience very similar diurnal tidal amplitudes. However, because Enceladus has a smaller radius it is likely to behave in a more rigid fashion than Europa, resulting in less tidal heating. Conventional (diurnal) tidal generation of the observed heat flux at Enceladus' south pole [4] requires Q/k2 of order 100, implying a relatively soft interior. Secondly, satellite rigidity controls both the magnitude of loads which are potentially capable of causing satellite reorientation, and the size of the opposing fossil bulge [5]. Finally, the near-surface rigidity (elastic thickness) influences, and may be deduced from, observations of the scale and morphology of surface tectonic features [6]. [1] Palguta et al. Icarus 180, 428-441, 2006 [2] Anderson et al. Icarus 153, 157-161, 2001 [3] McKinnon Icarus 130, 540-543, 1997 [4] Spencer et al., Science 311, 1401-1405, 2006 [5] Nimmo and Pappalardo, Nature 441, 614-616, 2006 [6] Nimmo and Schenk, J. Struct. Geol. in press.

  11. Rigid Cluster Decomposition Reveals Criticality in Frictional Jamming

    NASA Astrophysics Data System (ADS)

    Henkes, Silke; Quint, David A.; Fily, Yaouen; Schwarz, J. M.

    2016-01-01

    We study the nature of the frictional jamming transition within the framework of rigidity percolation theory. Slowly sheared frictional packings are decomposed into rigid clusters and floppy regions with a generalization of the pebble game including frictional contacts. Our method suggests a second-order transition controlled by the emergence of a system-spanning rigid cluster accompanied by a critical cluster size distribution. Rigid clusters also correlate with common measures of rigidity. We contrast this result with frictionless jamming, where the rigid cluster size distribution is noncritical.

  12. Antiplane SH-deformations near a surface rigid foundation above a subsurface rigid circular tunnel

    NASA Astrophysics Data System (ADS)

    Lee, V. W.; Manoogian, M. E.; Chen, S.

    2002-06-01

    The problem on the dynamic response of a rigid embedded foundation in the presence of an underground rigid tunnel and subjected to excitation of incident anti-plane SH waves is analyzed. By using the exact analytical solution for the two-dimensional SH-wave propagation in and around both the surface rigid foundation and subsurface rigid tunnel, those aspects of the resulting ground motions that are of special interest and importance for seismic resistant design in earthquake analyses have been examined. The computed amplitudes of the resulting periodic ground motions display a very complicated wave-interference between the surface foundation and underground tunnel that lead to observed standing wave patterns, together with abrupt changes in the wave amplitudes and large amplification of the incident motions.

  13. Development of laser ruler in rigid laryngoscope.

    PubMed

    Lee, Young-Ok; Kim, Byoung-Chul; Lee, Jung-Hoon; Lee, Jin-Choon; Lee, Byung-Joo; Wang, Soo-Geun; Ro, Jung-Hoon; Jeon, Gye-Rok; Shin, Bum-Joo

    2011-12-01

    The objective of this study was to develop a new device that provides a simple, noninvasive method of measuring accurate lesion size while using an endoscope. We developed a rigid laryngoscope with a built-in laser-ruler using a one-light emitting diode and an acrylic plate. The invention incorporates a built-in laser diode that projects an auto-parallel beam into the optical path of the rigid laryngoscope to form two spots in the field of view. While the interspot distance remains consistent despite changes in focal plane, magnification, or viewing angle of the laryngoscope, projection to an uneven surface introduces certain variations in the shape, and size of the spots, and the distance between the two spots. The device enables a laryngologist to easily measure the distance between landmarks, as well as the change in real size, and the progressive change of vocal fold lesions in an outpatient setting.

  14. 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.

  15. Progressive encephalomyelitis with rigidity and myoclonus

    PubMed Central

    Turner, M.R.; Irani, S.R.; Leite, M.I.; Nithi, K.; Vincent, A.

    2011-01-01

    Background: The syndrome of progressive encephalopathy with limb rigidity has been historically termed progressive encephalomyelitis with rigidity and myoclonus (PERM) or stiff-person syndrome plus. Methods: The case is presented of a previously healthy 28-year-old man with a rapidly fatal form of PERM developing over 2 months. Results: Serum antibodies to both NMDA receptors (NMDAR) and glycine receptors (GlyR) were detected postmortem, and examination of the brain confirmed an autoimmune encephalomyelitis, with particular involvement of hippocampal pyramidal and cerebellar Purkinje cells and relative sparing of the neocortex. No evidence for an underlying systemic neoplasm was found. Conclusion: This case displayed not only the clinical features of PERM, previously associated with GlyR antibodies, but also some of the features associated with NMDAR antibodies. This unusual combination of antibodies may be responsible for the particularly progressive course and sudden death. PMID:21775733

  16. Design of Overlays for Rigid Airport Pavements

    DTIC Science & Technology

    1988-04-01

    Renture, A., and Mindess , S. 1986. "The Effect of Concrete Strength on Crack Patterns," Cement and Concrete Research,_ Vol 16, Pergamon Press Ltd...34 Miscellaneous Paper S-74-30, US Army Engineer Waterways Experiment Station, Vicksburg, Miss. 22. Harr, M. E. 1977 . Mechanics of Particulate Media...of Civil -. Engineers, New York. 33. Hutchinson, R., and Vedros, P. 1977 . "Performance of Heavy-Load Port- land Cement Concrete (Rigid) Airfield

  17. Rigid plastic collars for marking geese

    USGS Publications Warehouse

    Ballou, R.M.; Martin, F.W.

    1964-01-01

    Rigid plastic collars of one to three colors proved useful for recognition of individual Canada geese (Branta canadensis). The collars did not seem to affect the behavior of the geese, and there was little mortality caused by their use. In good light, bright colors are visible through a 20-power spotting scope for more than 1 mile. Retention of collars was about 90 percent for 1 year and more than 80 percent for 2 years.

  18. Criteria for Hull-Machinery Rigidity Compatibility,

    DTIC Science & Technology

    1981-05-01

    articulated double-reduction gear design permits a * greater variety of arrangements with essentially the same rotating parts by rolling the pinion and...Additional intercostal girders are to be fitted within the double bottom to ensure the satisfactory distribution of the weight and the rigidity of the...and 124 arranged to distribute the loads effectively into the adjacent structure. Extra intercostal girders, effect- ively attached, are to be fitted

  19. Modular Habitats Comprising Rigid and Inflatable Modules

    NASA Technical Reports Server (NTRS)

    Kennedy, Kriss J.

    2010-01-01

    Modular, lightweight, fully equipped buildings comprising hybrids of rigid and inflatable structures can be assembled on Earth and then transported to and deployed on the Moon for use as habitats. Modified versions of these buildings could also prove useful on Earth as shelters that can be rapidly and easily erected in emergency situations and/or extreme environments: examples include shelters for hurricane relief and for Antarctic exploration.

  20. Rigid gas-permeable lens problem solving.

    PubMed

    Bennett, E S; Egan, D J

    1986-07-01

    The introduction of high oxygen-permeable rigid lenses for daily wear has provided practitioners with an excellent alternative to other available lens materials. However, compromise in material properties may, in fact, result in lens-induced complications. This paper describes eight such "typical" problems including a treatment plan and possible alternative methods of treatment. A comprehensive summary table is provided for reference use by practitioners.

  1. Optimizing Simulated Trajectories Of Rigid Bodies

    NASA Technical Reports Server (NTRS)

    Brauer, Garry L.; Olson, David W.; Stevenson, Robert

    1989-01-01

    6D POST is general-purpose, six-degree-of-freedom computer program for optimization of simulated trajectories of rigid bodies. Direct extension of three-degree-of-freedom POST program. 6D POST program models trajectory of powered or unpowered vehicle operating at or near rotating planet. Used to solve variety of performance, guidance, and flight-control problems for atmospheric and orbital vehicles. Written in FORTRAN 77 and FORTRAN V.

  2. 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.

  3. TLP rigid riser; A case study

    SciTech Connect

    Rooney, P.P.; Engebretsen, K.B. ); Pettersen, D.J. )

    1992-03-01

    This paper summarizes tension-leg platform (TLP) rigid riser design considerations and presents results of TLP riser analysis for a production/injection riser in the North Sea. Analysis methods, design criteria, and design optimization are addressed. The riser is designed for 300-m water depth in compliance with Norwegian regulations. Emphasis is placed on application of the regulations and quantitative comparison of alternative methods for analysis of fatigue and extremes.

  4. The Structure and Rigidity of Network Glasses

    NASA Astrophysics Data System (ADS)

    Thorpe, M. F.; Jacobs, D. J.; DjordjeviĆ, B. R.

    The following sections are included: * Introduction * Continuous Random Networks * Hand-built CRN models * Computer-built CRN models * Guttman model * Wooten-Weaire method * Constraint Counting * Generic Rigidity Percolation * The pebble game * Two dimensional central force networks * Three dimensional bond bending networks * Surface Floppy Modes * Basic counting techniques * Problems with periodic boundary conditions * Experiments * Bulk materials * Correction for dangling bonds * Silicate networks * Summary * Acknowledgments * References

  5. Infinitesimal rigidity of hyperquadrics in semi-Euclidean space

    NASA Astrophysics Data System (ADS)

    Shin, An Sook; Kim, Hobum; Han, Hyelim

    2016-12-01

    In this paper, we show that hyperquadrics are infinitesimally rigid in a semi-Euclidean space. We also show that hypersurfaces of hyperquadrics cut by hyperplanes not passing through the origin are infinitesimally rigid in the hyperquadrics, whereas those cut by hyperplanes through the origin are not infinitesimally rigid in hyperquadrics. Furthermore, we prove that any hypersurface in a semi-Euclidean space containing some open subset of a hyperplane is not infinitesimally rigid.

  6. 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... Deformable Barrier § 587.18 Dimensions of fixed rigid barrier. (a) The fixed rigid barrier has a mass of not less than 7 × 104 kg (154,324 lb). (b) The height of the fixed rigid barrier is at least as high as the...

  7. 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... Deformable Barrier § 587.18 Dimensions of fixed rigid barrier. (a) The fixed rigid barrier has a mass of not less than 7 × 104 kg (154,324 lb). (b) The height of the fixed rigid barrier is at least as high as the...

  8. Stability for the Lens Rigidity Problem

    NASA Astrophysics Data System (ADS)

    Bao, Gang; Zhang, Hai

    2017-09-01

    Let g be a Riemannian metric for R^d ({d ≥q 3}) which differs from the Euclidean metric only in a smooth and strictly convex bounded domain M. The lens rigidity problem is concerned with recovering the metric g inside M from the corresponding lens relation on the boundary {partial M}. In this paper, the stability of the lens rigidity problem is investigated for metrics which are a priori close to a given non-trapping metric satisfying the "strong fold-regular" condition. A metric g is called strong fold-regular if for each point {x\\in M}, there exists a set of geodesics passing through x whose conormal bundle covers {T^*xM}. Moreover, these geodesics contain either no conjugate points or only fold conjugate points with a non-degeneracy condition. Examples of strong fold-regular metrics are constructed. Our main result gives the first stability result for the lens rigidity problem in the case of anisotropic metrics which allow conjugate points. The approach is based on the study of the linearized inverse problem of recovering a metric from its induced geodesic flow, which is a weighted geodesic X-ray transform problem for symmetric 2-tensor fields. A key ingredient is to show that the kernel of the X-ray transform on symmetric solenoidal 2-tensor fields is of finite dimension. It remains open whether the kernel space is trivial or not.

  9. Pulling rigid bodies through granular material

    NASA Astrophysics Data System (ADS)

    Kubik, Ryan; Dressaire, Emilie

    2016-11-01

    The need for anchoring systems in granular materials such as sand is present in the marine transportation industry, e.g. to layout moorings, keep vessels and docks fixed in bodies of water, build oil rigs, etc. The holding power of an anchor is associated with the force exerted by the granular media. Empirical evidence indicates that the holding power depends on the size and shape of the anchoring structure. In this model study, we use a two-dimensional geometry in which a rigid body is pulled through a granular media at constant velocity to determine the drag and lift forces exerted by a granular medium on a moving object. The method allows measuring the drag force and recording the trajectory of the rigid object through the sand. We systematically vary the size and geometry of the rigid body, the properties of the granular medium and the extraction speed. For different initial positions of a cylindrical object pulled horizontally through the medium, we record large variations in magnitude of the drag and a significant lift force that pulls the object out of the sand.

  10. Geometric simulation of structures containing rigid units

    NASA Astrophysics Data System (ADS)

    Wells, Stephen

    2005-03-01

    Much insight into the behaviour of the framework silicates can be obtained from the Rigid Unit model. I review results from geometric analyses [1] of framework structures, quantifying the significance of rigid unit motion in thermal disorder and in defect accomodation, and from a method of simulation [2,3] based on a whole-body `geometric potential' rather than on interatomic potentials. I show the application of the geometric potential to the symmetry-constrained generation of hypothetical zeolite frameworks [4], and to the rapid generation of protein conformations using insights from rigid cluster decomposition [5]. 1. Wells, Dove and Tucker, Journal of Applied Crystallography, 37:536--544 (2004). 2. G.D. Gatta and S.A. Wells, Phys. Chem. Min. 31:1--10 (2004). 3. A. Sartbaeva, S. A. Wells, S. A. T. Redfern, J. Phys.: Condens. Matter 16, 8173 (2004) 4. M. M. J. Treacy, I. Rivin, E. Balkovsky, K. H. Randall and M. D. Foster, Micropor. Mesopor. Mater. 74, 121-132 (2004). 5. M.F. Thorpe, Ming Lei, A.J. Rader, Donald J. Jacobs, and Leslie A. Kuhn, Journal of Molecular Graphics and Modelling 19, 1:60 - 69, (2001).

  11. Defining optical distortion in rigid endoscopes.

    PubMed

    Abel, Eric; Fotiadis, Nikolaos; Miah, Mohammed; White, Paul

    2015-03-01

    To describe lens and perspective distortion using new measures that have practical meaning to the surgeon, and to apply these measures to show the extent of optical distortion in rigid endoscopes used in endoscopic sinus surgery. Laboratory measurements on rigid endoscopes. Barrel and perspective distortion were measured in 4-mm diameter 0°, 30°, 45°, and 70° rigid sinus endoscopes. Images of square grids were obtained with the endoscopes aligned in a specially constructed test rig. The terms relative size (RS) and relative distance (RD) were introduced to describe size and distance errors; and the term relative angle (RA) was used for assessing perspective errors. All the endoscopes exhibited similar barrel distortion. RS of the image at the periphery was 52%; RD was 80%. For RA values of 30°, 45°, and 70°, RS values were 77%, 58%, and 32%, respectively. Objects at the edge of the surgical field appear significantly more distant than suggested by their screen position. Perspective distortion occurs, unless RA = 0°. Barrel distortion of the lens helped to offset the effects of perspective distortion. Optical distortion can be quantified and understood using straightforward definitions. High levels of distortion are common, particularly due to perspective distortion, which is dependent on RA but independent of barrel distortion and the viewing angle of the endoscope. © 2014 The American Laryngological, Rhinological and Otological Society, Inc.

  12. Origin of rigidity in dry granular solids.

    PubMed

    Sarkar, Sumantra; Bi, Dapeng; Zhang, Jie; Behringer, R P; Chakraborty, Bulbul

    2013-08-09

    Solids are distinguished from fluids by their ability to resist shear. In traditional solids, the resistance to shear is associated with the emergence of broken translational symmetry as exhibited by a nonuniform density pattern. In this work, we focus on the emergence of shear rigidity in a class of solids where this paradigm is challenged. Dry granular materials have no energetically or entropically preferred density modulations. We show that, in contrast to traditional solids, the emergence of shear rigidity in these granular solids is a collective process, which is controlled solely by boundary forces, the constraints of force and torque balance, and the positivity of the contact forces. We develop a theoretical framework based on these constraints, which connects rigidity to broken translational symmetry in the space of forces, not positions of grains. We apply our theory to experimentally generated shear-jammed states and show that these states are indeed characterized by a persistent, non-uniform density modulation in force space, which emerges at the shear-jamming transition.

  13. Origin of Rigidity in Dry Granular Solids

    NASA Astrophysics Data System (ADS)

    Sarkar, Sumantra; Bi, Dapeng; Zhang, Jie; Behringer, R. P.; Chakraborty, Bulbul

    2013-08-01

    Solids are distinguished from fluids by their ability to resist shear. In traditional solids, the resistance to shear is associated with the emergence of broken translational symmetry as exhibited by a nonuniform density pattern. In this work, we focus on the emergence of shear rigidity in a class of solids where this paradigm is challenged. Dry granular materials have no energetically or entropically preferred density modulations. We show that, in contrast to traditional solids, the emergence of shear rigidity in these granular solids is a collective process, which is controlled solely by boundary forces, the constraints of force and torque balance, and the positivity of the contact forces. We develop a theoretical framework based on these constraints, which connects rigidity to broken translational symmetry in the space of forces, not positions of grains. We apply our theory to experimentally generated shear-jammed states and show that these states are indeed characterized by a persistent, non-uniform density modulation in force space, which emerges at the shear-jamming transition.

  14. "Sufficient health" as perceived by Thai villagers: A qualitative study.

    PubMed

    Arpanantikul, Manee; Phuphaibul, Rutja; Khuwatsumrit, Kusuma

    2017-01-05

    Globalization has led to the rapid modernization of Thai villagers' traditional lifestyle, with significant consequential changes in health. The integration of the sufficiency economy philosophy with health - a concept known as "sufficient health" - can improve health and wellbeing; however, little is known of the actual meaning of "sufficient health." This qualitative study explored the meaning of sufficient health as perceived by Thai villagers. Data were collected from 122 villagers living in a rural Thai community and analyzed using content analysis. The findings revealed five themes reflecting the meaning of sufficient health: being healthy and not having an illness, having regular health check-ups, performing self-care, living sufficiently, and avoiding risks. Understanding the meaning attributed to sufficient health can help nurses provide appropriate health care for villagers while retaining concern and respect for their cultural backgrounds. Importantly, providing opportunities to villagers to participate in health activities could help them recognize and sustain sufficient health.

  15. 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...

  16. 49 CFR 587.18 - Dimensions of fixed rigid barrier.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 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...

  17. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 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...

  18. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 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...

  19. 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...

  20. 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...

  1. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 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...

  2. 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...

  3. A Cognitive Developmental Model of Rigidity in Senescence.

    ERIC Educational Resources Information Center

    Lapsley, Daniel K.; Enright, Robert D.

    1983-01-01

    The rigidity construct is reinterpreted in terms of the cognitive developmental approach. A review reveals both cognitive and developmental themes, with an emphasis on the structural and operational properties of rigidity. Notes weaknesses of previous approaches to rigidity and discusses implications and predictions from the proposed model.…

  4. A Cognitive Developmental Model of Rigidity in Senescence.

    ERIC Educational Resources Information Center

    Lapsley, Daniel K.; Enright, Robert D.

    1983-01-01

    The rigidity construct is reinterpreted in terms of the cognitive developmental approach. A review reveals both cognitive and developmental themes, with an emphasis on the structural and operational properties of rigidity. Notes weaknesses of previous approaches to rigidity and discusses implications and predictions from the proposed model.…

  5. The limitations of using vertical cutoff rigidities determined from the IGRF magnetic field models for computing aircraft radiation dose.

    PubMed

    Smart, D F; Shea, M A

    2003-01-01

    Vertical cutoff rigidities derived from the International Geomagnetic Reference Fields (IGRF) are normally used to compute the radiation dose at a specific location and to organize the radiation dose measurements acquired at aircraft altitudes. This paper presents some of the usually ignored limits on the accuracy of the vertical cutoff rigidity models and describes some of the computational artifacts present in these models. It is noted that recent aircraft surveys of the radiation dose experienced along specific flight paths is sufficiently precise that the secular variation of the geomagnetic field is observable.

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

    SciTech Connect

    Usabiaga, Florencio Balboa; Kallemov, Bakytzhan; Delmotte, Blaise; Bhalla, Amneet Pal Singh; Griffith, Boyce E.; Donev, Aleksandar

    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 number 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, leading to

  8. 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

  9. 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.

  10. Fitting of aspheric high gas-permeable rigid contact lenses to scarred corneas.

    PubMed

    Kok, J H; Smulders, F; van Mil, C

    1991-08-15

    Scarring of the cornea often results in an irregular corneal surface, which causes scattering in light perception. Therefore, the impaired visual acuity cannot be adequately corrected by spectacles in most cases. In this study, high oxygen-transmissible aspheric rigid lenses were fitted, with computer assistance, in 26 scarred eyes of 23 consecutive patients. In 15 of 26 eyes (57.7%), a successful fitting with good vision, no complications, and a sufficiently long wearing time was accomplished. The main lens-related complications included fluorescein-staining epithelial defects in five of 26 eyes (19.2%) and epithelial edema in two of 26 eyes (7.7%). Computer-aided fitting was of limited value because keratometer readings were not measurable in 50% of the cases. The results of this study indicate that the application of high oxygen-transmissible aspheric rigid contact lenses may obviate corneal surgery.

  11. 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.

  12. 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.

  13. Brownian dynamics of confined rigid bodies

    SciTech Connect

    Delong, Steven; Balboa Usabiaga, Florencio; Donev, Aleksandar

    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 other 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.

  14. Brownian dynamics of confined rigid bodies.

    PubMed

    Delong, Steven; Balboa Usabiaga, Florencio; Donev, Aleksandar

    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 other 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.

  15. Brownian dynamics of confined rigid bodies

    NASA Astrophysics Data System (ADS)

    Delong, Steven; Balboa Usabiaga, Florencio; Donev, Aleksandar

    2015-10-01

    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 other 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.

  16. Mechanical Characterization of Rigid Polyurethane Foams

    SciTech Connect

    Lu, Wei-Yang

    2014-12-01

    Foam materials are used to protect sensitive components from impact loading. In order to predict and simulate the foam performance under various loading conditions, a validated foam model is needed and the mechanical properties of foams need to be characterized. Uniaxial compression and tension tests were conducted for different densities of foams under various temperatures and loading rates. Crush stress, tensile strength, and elastic modulus were obtained. A newly developed confined compression experiment provided data for investigating the foam flow direction. A biaxial tension experiment was also developed to explore the damage surface of a rigid polyurethane foam.

  17. Counterion-Induced Attraction between Rigid Polyelectrolytes

    SciTech Connect

    Gro Bruinsma, R.F.; Gro Mashl, R.J.; Gelbart, W.M.

    1997-03-01

    We report on results of long-time Brownian-dynamics simulations of electrostatic interactions between two rigid polyelectrolyte rods. We find that the interaction can be both repulsive, as obtained from mean-field theory, and attractive. The onset of attraction depends not only on the fixed charge density of the rod, but also on its radius. The attractive force is found to be due to the development of positional correlations between the counterions condensed on the two rods, for which we propose a simple analytical model. {copyright} {ital 1997} {ital The American Physical Society}

  18. The High Rigidity Spectrometer for FRIB

    NASA Astrophysics Data System (ADS)

    Baumann, T.

    2016-06-01

    The High Rigidity Spectrometer (HRS) is being developed to make optimum use of the fast rare-isotope beams that will be available at the Facility for Rare-Isotope Beams (FRIB) and will be the key experimental tool to study the most exotic, neutron-rich nuclei. The HRS will accommodate detector systems for charged particles, neutrons, and gamma rays. This will enable coincidence measurements of reaction products that stem from a variety of reactions such as knockout, breakup, charge exchange or Coulomb excitation. First-order ion optical studies are under way and this paper will offer some details on the current design ideas.

  19. A rigid porous filter and filtration method

    SciTech Connect

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

    1998-12-01

    The present invention involves a porous rigid filter comprising 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 particulate from high pressure particulate containing gases, and further involves a method for using the filter to remove such particulate. 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.

  20. Diffraction of sound by nearly rigid barriers

    NASA Technical Reports Server (NTRS)

    Hadden, W. J., Jr.; Pierce, A. D.

    1976-01-01

    The diffraction of sound by barriers with surfaces of large, but finite, acoustic impedance was analyzed. Idealized source-barrier-receiver configurations in which the barriers may be considered as semi-infinite wedges are discussed. Particular attention is given to situations in which the source and receiver are at large distances from the tip of the wedge. The expression for the acoustic pressure in this limiting case is compared with the results of Pierce's analysis of diffraction by a rigid wedge. An expression for the insertion loss of a finite impedance barrier is compared with insertion loss formulas which are used extensively in selecting or designing barriers for noise control.

  1. Laminarization of Turbulent Boundary Layer on Flexible and Rigid Surfaces

    NASA Technical Reports Server (NTRS)

    Maestrello, Lucio

    2001-01-01

    An investigation of the control of turbulent boundary layer flow over flexible and rigid surfaces downstream of a concave-convex geometry has been made. The concave-convex curvature induces centrifugal forces and a pressure gradient on the growth of the turbulent boundary layer. The favorable gradient is not sufficient to overcome the unfavorable; thus, the net effect is a destabilizing, of the flow into Gortler instabilities. This study shows that control of the turbulent boundary layer and structural loading can be successfully achieved by using localized surface heating because the subsequent cooling and geometrical shaping downstream over a favorable pressure gradient is effective in laminarization of the turbulence. Wires embedded in a thermally insulated substrate provide surface heating. The laminarized velocity profile adjusts to a lower Reynolds number, and the structure responds to a lower loading. In the laminarization, the turbulent energy is dissipated by molecular transport by both viscous and conductivity mechanisms. Laminarization reduces spanwise vorticity because of the longitudinal cooling gradient of the sublayer profile. The results demonstrate that the curvature-induced mean pressure gradient enhances the receptivity of the flow to localized surface heating, a potentially viable mechanism to laminarize turbulent boundary layer flow; thus, the flow reduces the response of the flexible structure and the resultant sound radiation.

  2. 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.

  3. Analytical study of rigidized fibrous materials

    NASA Technical Reports Server (NTRS)

    Rosen, B. W.; Bagchi, D.; Kibler, J. J.

    1974-01-01

    Insulation systems composed of micrometer-sized fibers bonded together with small amounts of binder have been developed for aerospace applications. The materials have a very high volid content and low density and can be characterized as a rigidized network of fibers randomly oriented in three-dimensional space. Analytical models suitable for the evaluation of the mechanical behavior of rigidized fibrous materials have been developed. The models treat the material as a space frame structure and includes the effects of joint fixity and fiber curvature. The geometrical and material property variabilities are represented by a number of trusses oriented in five planes. Each truss may have different material and geometric properties. Techniques have been developed to describe the continuous material property and geometry functions as a series of descrete quantities that can be used to describe each of the trusses in the model. Parametric studies were performed to show the influence of material variables on the mechanical behavior of the material. Results of calculations show good agreement with measured properties.

  4. Rigidity of triskelion arms and clathrin nets.

    PubMed Central

    Jin, A J; Nossal, R

    2000-01-01

    Statistical analysis is applied to a set of electron micrographic images (Kocsis, E., B. L. Trus, C. J. Steer, M. E. Bisher, and A. C. Steven. 1991. J. Struct. Biol. 107:6-14), from which quantitative measures are obtained to support the notion that the three arms of a triskelion have statistically identical properties and exhibit independent structural fluctuations. Additionally, a study of local contour fluctuations, which indicates that the elastic properties of a triskelion arm are approximately constant over the entire arm length, is used along with a small deformation statistical mechanics theory to derive an effective, average flexural rigidity for the arms. This result is used to estimate the bending energy necessary to deform a clathrin patch, and comparison is made with the deformation energy of an equivalent area of non-clathrin-coated membrane. We estimate that the rigidity of the clathrin lattice is at least comparable to that of a typical membrane. Hence, the natural curvature of a clathrin cage can stabilize, and perhaps propel, the formation of intracellular coated vesicles. PMID:10692308

  5. Magnetic Control of Rigid Achiral Microswimmers

    NASA Astrophysics Data System (ADS)

    Cheang, U.; Meshkati, Farshad; Fu, Henry; Kim, Minjun

    2013-11-01

    We report control of rigid achiral microswimmers in low Reynolds number environments. A rotating magnetic field was used to actuate the microswimmers wirelessly by rotating the microswimmers, which produces propulsion. Previous magnetically actuated microswimmers in bulk fluids have been designed with either flexibility or chiral geometry; we show that simpler geometries with neither flexibility nor chirality can produce propulsion. The microswimmer consists of three magnetic beads conjugated using avidin-biotin linkages into an arc formation. We designed a magnetic field generator consisting of electromagnetic coils arranged in an approximate Helmholtz configuration. A highspeed camera provided realtime imaging of the microswimmers' motion in a PDMS chamber. The rigidity of the microswimmer was characterized by tracking the position of the individual beads and calculating their relative distances. As a function of field strength and rotation frequency, we observed changes in the rotational axis of the microswimmers and the corresponding effects on their velocities. The achiral microswimmers exhibited active propulsion and were controllable in both speed and direction, which demonstrates the possibility for future biomedical applications such as drug delivery.

  6. Vertebral Column Resection for Rigid Spinal Deformity

    PubMed Central

    Laratta, Joseph L.; Petridis, Petros; Shillingford, Jamal N.; Lehman, Ronald A.; Lenke, Lawrence G.

    2017-01-01

    Study Design: Broad narrative review. Objective: To review the evolution, operative technique, outcomes, and complications associated with posterior vertebral column resection. Methods: A literature review of posterior vertebral column resection was performed. The authors’ surgical technique is outlined in detail. The authors’ experience and the literature regarding vertebral column resection are discussed at length. Results: Treatment of severe, rigid coronal and/or sagittal malalignment with posterior vertebral column resection results in approximately 50–70% correction depending on the type of deformity. Surgical site infection rates range from 2.9% to 9.7%. Transient and permanent neurologic injury rates range from 0% to 13.8% and 0% to 6.3%, respectively. Although there are significant variations in EBL throughout the literature, it can be minimized by utilizing tranexamic acid intraoperatively. Conclusion: The ability to correct a rigid deformity in the spine relies on osteotomies. Each osteotomy is associated with a particular magnitude of correction at a single level. Posterior vertebral column resection is the most powerful posterior osteotomy method providing a successful correction of fixed complex deformities. Despite meticulous surgical technique and precision, this robust osteotomy technique can be associated with significant morbidity even in the most experienced hands. PMID:28660112

  7. Understanding rigid body motion in arbitrary dimensions

    NASA Astrophysics Data System (ADS)

    Leyvraz, Francois

    2015-05-01

    Why would anyone wish to generalize the already unappetizing subject of rigid body motion to an arbitrary number of dimensions? At first sight, the subject seems to be both repellent and superfluous. The author will try to argue that an approach involving no specific three-dimensional constructs is actually easier to grasp than the traditional approach and might thus be generally useful to understand rigid body motion both in three dimensions and in the general case. Specific differences between the viewpoint suggested here and the usual one include the following: here angular velocities are systematically treated as antisymmetric matrices, a symmetric tensor I quite different from the moment of inertia tensor plays a central role, whereas the latter is shown to be a far more complex object, namely a tensor of rank four. A straightforward way to define it is given. The Euler equation is derived and the use of Noether’s theorem to obtain conserved quantities is illustrated. Finally the equations of motion for a heavy top as well as for two bodies linked by a spherical joint are derived to display the simplicity and the power of the method.

  8. Vertebral Column Resection for Rigid Spinal Deformity.

    PubMed

    Saifi, Comron; Laratta, Joseph L; Petridis, Petros; Shillingford, Jamal N; Lehman, Ronald A; Lenke, Lawrence G

    2017-05-01

    Broad narrative review. To review the evolution, operative technique, outcomes, and complications associated with posterior vertebral column resection. A literature review of posterior vertebral column resection was performed. The authors' surgical technique is outlined in detail. The authors' experience and the literature regarding vertebral column resection are discussed at length. Treatment of severe, rigid coronal and/or sagittal malalignment with posterior vertebral column resection results in approximately 50-70% correction depending on the type of deformity. Surgical site infection rates range from 2.9% to 9.7%. Transient and permanent neurologic injury rates range from 0% to 13.8% and 0% to 6.3%, respectively. Although there are significant variations in EBL throughout the literature, it can be minimized by utilizing tranexamic acid intraoperatively. The ability to correct a rigid deformity in the spine relies on osteotomies. Each osteotomy is associated with a particular magnitude of correction at a single level. Posterior vertebral column resection is the most powerful posterior osteotomy method providing a successful correction of fixed complex deformities. Despite meticulous surgical technique and precision, this robust osteotomy technique can be associated with significant morbidity even in the most experienced hands.

  9. 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.

  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. Birationally rigid varieties with a pencil of Fano double covers. II

    NASA Astrophysics Data System (ADS)

    Pukhlikov, A. V.

    2004-12-01

    The study of the birational geometry of Fano fibrations \\pi\\colon V\\to\\mathbb P^1 whose fibres are Fano double hypersurfaces of index 1 is continued. Birational rigidity is proved for the majority of families of this type, which do not satisfy the condition of sufficient twistedness over the base (in particular, this means that there exist no other structures of a fibration into rationally connected varieties) and the groups of birational self-maps are computed. The principal components of the method of maximal singularities are considerably improved, chiefly the techniques of counting multiplicities for fibrations V/\\mathbb P^1 into Fano varieties over the line.

  13. Elastic image registration via rigid object motion induced deformation

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaofen; Udupa, Jayaram K.; Hirsch, Bruce E.

    2011-03-01

    In this paper, we estimate the deformations induced on soft tissues by the rigid independent movements of hard objects and create an admixture of rigid and elastic adaptive image registration transformations. By automatically segmenting and independently estimating the movement of rigid objects in 3D images, we can maintain rigidity in bones and hard tissues while appropriately deforming soft tissues. We tested our algorithms on 20 pairs of 3D MRI datasets pertaining to a kinematic study of the flexibility of the ankle complex of normal feet as well as ankles affected by abnormalities in foot architecture and ligament injuries. The results show that elastic image registration via rigid object-induced deformation outperforms purely rigid and purely nonrigid approaches.

  14. 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.

  15. 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

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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…

  2. Rigid and Flexible Pavement Aircraft Tie-Downs

    DTIC Science & Technology

    2010-05-01

    AFRL-RX-TY-TR-2010-0093 RIGID AND FLEXIBLE PAVEMENT AIRCRAFT TIE-DOWNS Christopher Jackson and Athar Saeed Applied Research Associates...MAR-2010 Rigid and Flexible Pavement Aircraft Tie-Downs FA4819-09-C-0028 62102F 4915 D1 4915D14E *Jackson, Christopher J.; *Saeed, Athar; **Lackey...tie-downs, although additional testing is necessary before recommending this option. rigid pavement aircraft tie-downs, flexible pavement aircraft

  3. Static friction between rigid fractal surfaces

    NASA Astrophysics Data System (ADS)

    Alonso-Marroquin, Fernando; Huang, Pengyu; Hanaor, Dorian A. H.; Flores-Johnson, E. A.; Proust, Gwénaëlle; Gan, Yixiang; Shen, Luming

    2015-09-01

    Using spheropolygon-based simulations and contact slope analysis, we investigate the effects of surface topography and atomic scale friction on the macroscopically observed friction between rigid blocks with fractal surface structures. From our mathematical derivation, the angle of macroscopic friction is the result of the sum of the angle of atomic friction and the slope angle between the contact surfaces. The latter is obtained from the determination of all possible contact slopes between the two surface profiles through an alternative signature function. Our theory is validated through numerical simulations of spheropolygons with fractal Koch surfaces and is applied to the description of frictional properties of Weierstrass-Mandelbrot surfaces. The agreement between simulations and theory suggests that for interpreting macroscopic frictional behavior, the descriptors of surface morphology should be defined from the signature function rather than from the slopes of the contacting surfaces.

  4. Turbulence closure modeling near rigid boundaries

    NASA Technical Reports Server (NTRS)

    Durbin, Paul A.

    1991-01-01

    The near-wall region plays an essential role in turbulent boundary layers: it is a region of high shear; the peak rate of production and peak intensity of turbulence occurs there; and the peak rate of dissipation occurs right at the wall. Nevertheless, this region has received less attention from modelers than have more nearly homogeneous flows. One reason for this is that when the boundary layer is near equilibrium, experimental data can be used to prescribe the flow in the wall layer. Another reason is that most turbulence models are developed under assumptions of near homogeneity. This is a poor approximation in the wall region. A single-point moment closure model for the strongly non-homogeneous A turbulent flow near a rigid boundary is developed.

  5. Discrete Time Crystals: Rigidity, Criticality, and Realizations

    NASA Astrophysics Data System (ADS)

    Yao, N. Y.; Potter, A. C.; Potirniche, I.-D.; Vishwanath, A.

    2017-01-01

    Despite being forbidden in equilibrium, spontaneous breaking of time translation symmetry can occur in periodically driven, Floquet systems with discrete time-translation symmetry. The period of the resulting discrete time crystal is quantized to an integer multiple of the drive period, arising from a combination of collective synchronization and many body localization. Here, we consider a simple model for a one-dimensional discrete time crystal which explicitly reveals the rigidity of the emergent oscillations as the drive is varied. We numerically map out its phase diagram and compute the properties of the dynamical phase transition where the time crystal melts into a trivial Floquet insulator. Moreover, we demonstrate that the model can be realized with current experimental technologies and propose a blueprint based upon a one dimensional chain of trapped ions. Using experimental parameters (featuring long-range interactions), we identify the phase boundaries of the ion-time-crystal and propose a measurable signature of the symmetry breaking phase transition.

  6. Rigidity Loss in Disordered Systems: Three Scenarios

    NASA Astrophysics Data System (ADS)

    Ellenbroek, Wouter G.; Hagh, Varda F.; Kumar, Avishek; Thorpe, M. F.; van Hecke, Martin

    2015-04-01

    We reveal significant qualitative differences in the rigidity transition of three types of disordered network materials: randomly diluted spring networks, jammed sphere packings, and stress-relieved networks that are diluted using a protocol that avoids the appearance of floppy regions. The marginal state of jammed and stress-relieved networks are globally isostatic, while marginal randomly diluted networks show both overconstrained and underconstrained regions. When a single bond is added to or removed from these isostatic systems, jammed networks become globally overconstrained or floppy, whereas the effect on stress-relieved networks is more local and limited. These differences are also reflected in the linear elastic properties and point to the highly effective and unusual role of global self-organization in jammed sphere packings.

  7. Supramolecular Synthons: Will Giant Rigid Superspheres Do?

    PubMed Central

    2016-01-01

    For the first time, the concept of supramolecular synthons was applied to giant rigid superspheres based on pentaphosphaferrocene [CpRFe(η5-P5)] (R = Me, Et) and Cu(I) halides, which reach 2.1–3.0 nm in diameter. Two supramolecular synthons, σ–π and π–π, are discovered based on halogen···CpR and Cp*···Cp* specific interactions, respectively. The geometry of the synthons is reproducible in a series of crystal structures of various supramolecules. The σ–π synthon alone is realized more frequently for Br-containing superspheres. A combination of the σ–π and π–π synthons is more typical for Cl-containing supramolecules. Each supramolecule can bear up to nine synthons to give mostly 2D and 3D architectures. PMID:27081373

  8. Static friction between rigid fractal surfaces.

    PubMed

    Alonso-Marroquin, Fernando; Huang, Pengyu; Hanaor, Dorian A H; Flores-Johnson, E A; Proust, Gwénaëlle; Gan, Yixiang; Shen, Luming

    2015-09-01

    Using spheropolygon-based simulations and contact slope analysis, we investigate the effects of surface topography and atomic scale friction on the macroscopically observed friction between rigid blocks with fractal surface structures. From our mathematical derivation, the angle of macroscopic friction is the result of the sum of the angle of atomic friction and the slope angle between the contact surfaces. The latter is obtained from the determination of all possible contact slopes between the two surface profiles through an alternative signature function. Our theory is validated through numerical simulations of spheropolygons with fractal Koch surfaces and is applied to the description of frictional properties of Weierstrass-Mandelbrot surfaces. The agreement between simulations and theory suggests that for interpreting macroscopic frictional behavior, the descriptors of surface morphology should be defined from the signature function rather than from the slopes of the contacting surfaces.

  9. Water dynamics in rigid ionomer networks

    NASA Astrophysics Data System (ADS)

    Osti, N. C.; Etampawala, T. N.; Shrestha, U. M.; Aryal, D.; Tyagi, M.; Diallo, S. O.; Mamontov, E.; Cornelius, C. J.; Perahia, D.

    2016-12-01

    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.

  10. [Use of rigid gas permeable contact lenses].

    PubMed

    Habela, M

    1992-01-01

    By application of contact lenses destined for a extended wearing, for preservation of a normal structure and metabolism of the cornea a considerable permeability of the contact lens for oxygen is necessary (Dk/L 75-80). The actually most popular in the world soft contact lenses have no such parameters. The application of rigid lenses produced from materials of high permeability for oxygen enables the extended wearing without substantial disturbances of the corneal metabolism. The paper presents a new generation of fluoro-silicone acrylates used for the production of contact lenses permeable for oxygen. Discussed are the problems connected with the adjusting of these lenses, their tolerance and influence on the corneal metabolism.

  11. Acoustic propagation in a rigid torus

    NASA Technical Reports Server (NTRS)

    El-Raheb, M.; Wagner, P.

    1982-01-01

    The acoustic propagation in a rigid torus is analyzed using a Green's function method. Three types of surface elements are developed; a flat quadrilateral element used in modeling polygonal cavities, a curved conical element appropriate for surfaces with one curvature, and a toroidal element developed for such doubly curved surfaces as the torus. Curved elements are necessary since the acoustic pressure is sensitive to slope discontinuities between consecutive surface elements especially near cavity resonances. The acoustic characteristics of the torus are compared to those of a bend of square cross section for a frequency range that includes the transverse acoustic resonance. Two equivalences between the different sections are tested; the first conserves curvature and cross-sectional dimension while the second matches transverse resonance and duct volume. The second equivalence accurately matches the acoustic characteristics of the torus up to the cutoff frequency corresponding to a mode with two circumferential waves.

  12. Non-rigid precession of magnetic stars

    NASA Astrophysics Data System (ADS)

    Lander, S. K.; Jones, D. I.

    2017-06-01

    Stars are, generically, rotating and magnetized objects with a misalignment between their magnetic and rotation axes. Since a magnetic field induces a permanent distortion to its host, it provides effective rigidity even to a fluid star, leading to bulk stellar motion that resembles free precession. This bulk motion is, however, accompanied by induced interior velocity and magnetic field perturbations, which are oscillatory on the precession time-scale. Extending previous work, we show that these quantities are described by a set of second-order perturbation equations featuring cross-terms scaling with the product of the magnetic and centrifugal distortions to the star. For the case of a background toroidal field, we reduce these to a set of differential equations in radial functions, and find a method for their solution. The resulting magnetic field and velocity perturbations show complex multipolar structure and are strongest towards the centre of the star.

  13. Rigid body constrained noisy point pattern matching.

    PubMed

    Morgera, S D; Cheong, P C

    1995-01-01

    Noisy pattern matching problems arise in many areas, e.g., computational vision, robotics, guidance and control, stereophotogrammetry, astronomy, genetics, and high-energy physics. Least-squares pattern matching over the Euclidean space E(n) for unordered sets of cardinalities p and q is commonly formulated as a combinatorial optimization problem having complexity p(p-1)...(p-q+1), q=/rigid motion constraints, which often apply. The method reduces the complexity to l(21).n(4)+l(12).p(3), where l(12) and l(21) are the number of iterations required by steepest-ascent and singular value decomposition (SVD)-based procedures, respectively.

  14. Hybrid Flexible and Rigid Ceramic Insulation

    NASA Technical Reports Server (NTRS)

    Rasky, Daniel J. (Inventor); Kourtides, Demetrius A. (Inventor)

    1996-01-01

    A method is provided for closing out the edges of a flexible ceramic insulation member including inner and outer mold line covering layers. A rigid, segmented, ceramic frame is placed round the edges of the insulation member and exposed edges of the inner and outer mold line covering layers are affixed to the ceramic frame. In one embodiment wherein the covering layers comprise fabrics, the outer fabric is bonded to the top surface and to grooved portion of the side surface of the frame. In another embodiment wherein the outer cover layer comprises a metallic foil, clips on the edges of the frame are used to engage foil extensions. The ceramic frame is coated with a high emittance densifier coating.

  15. Discrete Time Crystals: Rigidity, Criticality, and Realizations.

    PubMed

    Yao, N Y; Potter, A C; Potirniche, I-D; Vishwanath, A

    2017-01-20

    Despite being forbidden in equilibrium, spontaneous breaking of time translation symmetry can occur in periodically driven, Floquet systems with discrete time-translation symmetry. The period of the resulting discrete time crystal is quantized to an integer multiple of the drive period, arising from a combination of collective synchronization and many body localization. Here, we consider a simple model for a one-dimensional discrete time crystal which explicitly reveals the rigidity of the emergent oscillations as the drive is varied. We numerically map out its phase diagram and compute the properties of the dynamical phase transition where the time crystal melts into a trivial Floquet insulator. Moreover, we demonstrate that the model can be realized with current experimental technologies and propose a blueprint based upon a one dimensional chain of trapped ions. Using experimental parameters (featuring long-range interactions), we identify the phase boundaries of the ion-time-crystal and propose a measurable signature of the symmetry breaking phase transition.

  16. Advanced Rigid Ablative Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Feldman, J. D.; Gasch, M. J.; Poteet, C. C.; Szalai, Christine

    2012-01-01

    With the gradual increase in robotic rover sophistication and the desire for humans to explore the solar system, the need for reentry systems to deliver large payloads into planetary atmospheres is looming. Heritage ablative Thermal Protection Systems (TPS) using Viking or Pathfinder era materials are at or near their performance limits and will be inadequate for many future missions. Significant advances in TPS materials technology are needed in order to enable susequent human exploration missions. This paper summarizes some recent progress at NASA in developing families of advanced rigid ablative TPS that could be used for thermal protection in planetary entry missions. In particular, the effort focuses on technologies required to land heavy masses on Mars to facilitate exploration.

  17. Foam inflated rigidized structures for space applications

    NASA Astrophysics Data System (ADS)

    Lester, D. M.; Warner, M. J.; Blair, M.

    1993-11-01

    Large lightweight stowable structures that can be deployed in space without astronaut extra vehicular activity are vital to expanding space exploration and utilization. To meet this challenge Foam Inflated Rigidized (FIR) structures have been developed by Thiokol Corporation on the Air Forces's Gossamer Baggie Torus program. In this paper the development, proof of concept demonstration of an eight foot diameter octagonal torus, and design application of this technology for structural elements to stabilize the solar collector of a solar thermal rocket are discussed. A FIR structure uses foam to inflate and pre-stress a resin impregnated fabric skin. The predeployed foam used was a solvent swelled polymer that foams immediately when exposed to vacuum due to rapid solvent loss. This property allows a very simple deployment mechanism to be used in erecting these structures. Once inflated, the skin resin is cured using the available ultraviolet radiation. By using high strength and stiffness fiber materials a stiff, strong lightweight structure was produced.

  18. 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.

  19. Coherent distributions for the rigid rotator

    SciTech Connect

    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 Schrödinger equation.

  20. Secondary cavitation in a rigid tube

    NASA Astrophysics Data System (ADS)

    Ji, Chen; Li, Bo; Zou, Jun

    2017-08-01

    The oscillation of a single spark-generated bubble in a rigid tube is studied experimentally, with the help of a high-speed camera and a hydrophone. The non-dimensional collapse position XF is divided into three regimes, according to the various phenomena after the first oscillation period T1. In an asymmetric regime, secondary cavitation is observed. Both the axial position and the oscillation period of the secondary cavitation show a linear correlation with the first bubble. The period ratio k is independent of the relative bubble size L1* but is affected by the tube diameter Dt. In a symmetric regime, the secondary cavitation is much weaker and unrepeatable. The rebound bubble is strengthened in this regime, and the rebound ratio kr is independent of both L1* and Dt. A mechanism of reflected rarefaction wave is proposed to explain the position relation between the first and secondary cavities, and the energy partition in different regimes is discussed.

  1. Modeling Decomposition of Unconfined Rigid Polyurethane Foam

    SciTech Connect

    HOBBS,MICHAEL L.; ERICKSON,KENNETH L.; CHU,TZE YAO

    1999-11-08

    The decomposition of unconfined rigid polyurethane foam has been modeled by a kinetic bond-breaking scheme describing degradation of a primary polymer and formation of a thermally stable secondary polymer. The bond-breaking scheme is resolved using percolation theory to describe evolving polymer fragments. The polymer fragments vaporize according to individual vapor pressures. Kinetic parameters for the model were obtained from Thermal Gravimetric Analysis (TGA). The chemical structure of the foam was determined from the preparation techniques and ingredients used to synthesize the foam. Scale-up effects were investigated by simulating the response of an incident heat flux of 25 W/cm{sup 2} on a partially confined 8.8-cm diameter by 15-cm long right circular cylinder of foam that contained an encapsulated component. Predictions of center, midradial, and component temperatures, as well as regression of the foam surface, were in agreement with measurements using thermocouples and X-ray imaging.

  2. Modeling Decomposition of Unconfined Rigid Polyurethane Foam

    SciTech Connect

    CHU,TZE YAO; ERICKSON,KENNETH L.; HOBBS,MICHAEL L.

    1999-11-01

    The decomposition of unconfined rigid polyurethane foam has been modeled by a kinetic bond-breaking scheme describing degradation of a primary polymer and formation of a thermally stable secondary polymer. The bond-breaking scheme is resolved using percolation theory to describe evolving polymer fragments. The polymer fragments vaporize according to individual vapor pressures. Kinetic parameters for the model were obtained from Thermal Gravimetric Analysis (TGA). The chemical structure of the foam was determined from the preparation techniques and ingredients used to synthesize the foam. Scale-up effects were investigated by simulating the response of an incident heat flux of 25 W/cm{sup 2} on a partially confined 8.8-cm diameter by 15-cm long right circular cylinder of foam which contained an encapsulated component. Predictions of center, midradial, and component temperatures, as well as regression of the foam surface, were in agreement with measurements using thermocouples and X-ray imaging.

  3. Cast articulation accuracy using rigid cast stabilization.

    PubMed

    Gunderson, Ronald Bruce; Siegel, Sharon Crane

    2002-06-01

    This study evaluated the positional accuracy of casts articulated on a semi-adjustable articulator, with and without rigid cast stabilization using either laboratory plaster or mounting plaster. A reference articulation of melamine casts in maximum articulation was established and recorded in the horizontal and vertical dimensions using a verification device. The same casts were subsequently remounted 24 times using either laboratory plaster or mounting plaster. Half of the articulations from each group were stabilized using detachable mounting rods and sticky wax, and half were hand-articulated without stabilization, for a total of 6 articulations in each of 4 test groups. The resulting spatial positions established on the articulator were compared to the initial reference position on the verification device grid. Means and standard deviations of the absolute values of the horizontal and vertical displacement for each group were determined separately and compared using a one-way anaylsis of variance. Significant differences (p <0.05) were identified using Tukey's honestly significant difference multiple comparison test. Mean vertical mandibular cast displacement ranged from 0.26 +/-0.21mm for stabilized casts mounted with laboratory plaster to 1.58 +/-0.32 mm for unstabilized casts mounted with mounting plaster. For each mounting material, significantly less vertical displacement (p <0.001) was observed with the mandibular cast stabilized before mounting. The cast mounted with laboratory plaster exhibited horizontal displacement (0.87 +/-0.29 mm) that was significantly greater than the remaining groups (p <0.001), which did not differ from each other. Rigid stabilization of the mandibular to maxillary cast during mounting with laboratory and mounting plaster improved articulation accuracy. Copyright 2002 by The American College of Prosthodontists.

  4. A kidney deformation model for use in non-rigid registration during image-guided surgery

    NASA Astrophysics Data System (ADS)

    Ong, Rowena E.; Herrell, S. Duke, III; Miga, Michael I.; Galloway, Robert L., Jr.

    2008-03-01

    In order to facilitate the removal of tumors during partial nephrectomies, an image-guided surgery system may be useful. This system would require a registration of the physical kidney to a pre-operative image volume; however, it is unclear whether a rigid registration would be sufficient. One possible source of non-rigid deformation is the clamping of the renal artery during surgery and the subsequent loss of pressure as the kidney is punctured and blood loss occurs. To explore this issue, a model of kidney deformation due to loss of perfusion and pressure was developed based on Biot's consolidation model. The model was tested on two resected porcine kidneys in which the renal artery and vein were clamped. CT image volumes of the kidney were obtained before and after the deformation caused unclamping, and fiducial markers embedded on the kidney surface allowed the deformation to be tracked. The accuracy of the kidney model was accessed by calculating the model error at the fiducial locations and using image similarity measures. Preliminary results indicate that the model may be useful in a non-rigid registration scheme; however, further refinements to the model may be necessary to better simulate the deformation due to loss of perfusion and pressure.

  5. Conformational analysis of tripeptides: a molecular dynamics study of rigid and non-rigid tripeptides

    NASA Astrophysics Data System (ADS)

    Shibata, John; Mochel, Mark

    2006-03-01

    Molecular dynamics simulations have been performed on different tripeptides classified as structurally rigid and non-rigid (1). The simulations were run using the OPLS-AA force field (2) with and without explicit solvent. Two modeling programs, Tinker (3) and Macromodel (4), were used to simulate the dynamics. The accessible conformations were analyzed using Ramachandran plots of the dihedral angles. The results of this study are compared to the rigidity classification scheme (1), and differences in the results using explicit solvent and a continuum solvent model are noted. (1) Anishetty, S., Pennathur, G., Anishetty, R. BMC Structural Biology 2:9 (2002). Available from http://www.biomedcentral.com/1472-6807/2/9. (2) Jorgensen, W. L., Maxwell, D. S., Tirado-Rives, J. J. Am. Chem. Soc. 118, 11225 (1996). (3) Dudek, M. J., Ramnarayan, K., Ponder, J. W. J. Comput. Chem. 19, 548 (1996). Available from http://dasher.wustl.edu/tinker. (4) Mohamadi, F., Richards, N. G. J., Guida, W. C., Liskamp, R., Lipton, M., Caufield, C., Chang, G., Hendrickson, T., Still, W. C. J. Comput. Chem. 11, 440 (1990).

  6. Integrated power and attitude control of a rigid satellite with onboard magnetic bearing suspended rigid flywheels

    NASA Astrophysics Data System (ADS)

    Kim, Yeonkyu

    2003-10-01

    A system of differential equations governing the translational and rotational motion of a system model consisting of a rigid satellite and multiple MB suspended rigid flywheels in general configuration is developed. Flywheel modules are contained in a housing rigidly mounted on the satellite and floated by an active MB suspension system, therefore each flywheel module has six degrees of freedom (DOF) as well as the satellite module. Equations of motion for the satellite and flywheels are naturally coupled and the satellite rotational motion and translational motion are coupled. A nonlinear state feedback tracking control law, which is globally asymptotically stable, is developed following a Lyapunov stability theory for integrated power and attitude control using the MB suspended flywheels. The stability, robustness, and tracking and disturbance rejection performance of the present control law with respect to initial attitude error, system modeling error, an imbalance disturbance, is demonstrated by case studies. The satellite departure motion equation derived from the definition of the angular velocity error and the system dynamics equations is presented. Application study of existing power tracking algorithm with this control law shows perfect power tracking for both power charging from and power delivery to the satellite operations and the power tracking can be performed simultaneously with and independent of the attitude control function.

  7. 29 CFR 4041.48 - Sufficient plans; notice requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... TERMINATIONS TERMINATION OF SINGLE-EMPLOYER PLANS Distress Termination Process § 4041.48 Sufficient plans... distributed in the form of a nonconsensual lump sum; and (ii) The PBGC. (2) Spin-off/termination transactions...

  8. 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…

  9. [Unilateral abolition of parkinsonian rigidity after subthalamic nucleus hemorrhage].

    PubMed

    Yamada, A; Takeuchi, H; Miki, H

    1992-08-01

    A 63-year-old man with parkinsonism suddenly developed a right hemiballism, and the CT showed a hematoma of the left subthalamic nucleus. After the ballistic movement had disappeared, muscular rigidity improved on the right. This case suggests that excessive output from the subthalamic nucleus to the internal segment of globus pallidus plays a critical role in the pathophysiology of parkinsonian rigidity.

  10. 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...

  11. 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…

  12. 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…

  13. 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...

  14. 21 CFR 876.3630 - Penile rigidity implant.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 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...

  15. International challenges of self-sufficiency in blood products.

    PubMed

    Dhingra, N

    2013-05-01

    To face known and emerging threats to public health, all countries have to overcome the challenges of providing sufficient supplies of blood and blood products of the highest quality and safety. Unfortunately, self-sufficiency is not yet a reality in many countries. In 2011, experts from WHO addressed the urgent need to establish strategies and mechanisms for achieving this goal. A summary of these recommendations is further discussed. Copyright © 2013 N. Dhingra. Published by Elsevier SAS.. All rights reserved.

  16. 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

  17. Constructors, Sufficient Completeness, and Deadlock Freedom of Rewrite Theories

    NASA Astrophysics Data System (ADS)

    Rocha, Camilo; Meseguer, José

    Sufficient completeness has been throughly studied for equational specifications, where function symbols are classified into constructors and defined symbols. But what should sufficient completeness mean for a rewrite theory R = (Σ,E,R) with equations E and non-equational rules R describing concurrent transitions in a system? This work argues that a rewrite theory naturally has two notions of constructor: the usual one for its equations E, and a different one for its rules R. The sufficient completeness of constructors for the rules R turns out to be intimately related with deadlock freedom, i.e., R has no deadlocks outside the constructors for R. The relation between these two notions is studied in the setting of unconditional order-sorted rewrite theories. Sufficient conditions are given allowing the automatic checking of sufficient completeness, deadlock freedom, and other related properties, by propositional tree automata modulo equational axioms such as associativity, commutativity, and identity. They are used to extend the Maude Sufficient Completeness Checker from the checking of equational theories to that of both equational and rewrite theories. Finally, the usefulness of the proposed notion of constructors in proving inductive theorems about the reachability rewrite relation →_R associated to a rewrite theory R (and also about the joinability relation downarrow_R) is both characterized and illustrated with an example.

  18. Determination of the rigidity scale of the Alpha Magnetic Spectrometer

    NASA Astrophysics Data System (ADS)

    Berdugo, J.; Choutko, V.; Delgado, C.; Yan, Q.

    2017-10-01

    The Alpha Magnetic Spectrometer (AMS) experiment aboard the International Space Station has been collecting data since May 2011. The AMS silicon tracker accurately determines the trajectory of charged particles. Together with the magnet, it measures the rigidity (momentum per unit charge) of cosmic rays in the range from ∼0.5 GV to several TV. The precise knowledge of the rigidity scale is of critical importance to the physics goals of the experiment. The method to establish the tracker rigidity scale by using electron and positron events is presented. It allowed validation of the tracker alignment and estimation of the potential rigidity scale shifts. Using 5 years of AMS data, the tracker rigidity scale was measured with an accuracy of ±0.030(stat) ±0.017(sys) TV-1, limited mostly by available positron statistics.

  19. Rigidity sensing and adaptation through regulation of integrin types

    PubMed Central

    Elosegui-Artola, Alberto; Bazellières, Elsa; Allen, Michael D.; Andreu, Ion; Oria, Roger; Sunyer, Raimon; Gomm, Jennifer J.; Marshall, John F.; Jones, J. Louise; Trepat, Xavier; Roca-Cusachs, Pere

    2014-01-01

    Tissue rigidity regulates processes in development, cancer and wound healing. However, how cells detect rigidity, and thereby modulate their behaviour, remains unknown. Here, we show that sensing and adaptation to matrix rigidity in breast myoepithelial cells is determined by the bond dynamics of different integrin types. Cell binding to fibronectin through either α5β1 integrins (constitutively expressed) or αvβ6 integrins (selectively expressed in cancer and development) adapts force generation, actin flow, and integrin recruitment to rigidities associated with healthy or malignant tissue, respectively. In vitro experiments and theoretical modelling further demonstrate that this behaviour is explained by the different binding and unbinding rates of both integrin types to fibronectin. Moreover, rigidity sensing through differences in integrin bond dynamics applies both when integrins bind separately and when they compete for binding to fibronectin. PMID:24793358

  20. Flower Constellations as rigid objects in space

    NASA Astrophysics Data System (ADS)

    Mortari, Daniele

    2006-08-01

    This paper summarizes the findings and the research status on Flower Constellations, a novel and revolutionary way to design satellite constellations that has been discovered and proposed at Texas A&M University. The theory of Flower Constellations is a natural consequence of the theory of compatible (or resonant) orbits. The most surprising aspect of the Flower Constellations is that the satellite distribution identifies the edges of rotating figures whose shapes are time invariant. The complex synchronized dynamics of the satellites preserves the shape of a space object. The whole Flower Constellation is an axial-symmetric rigid object in space that is spinning with prescribed angular velocity. The shape of this object can be deformed by playing with the Flower Constellation design parameters, and the object's axis of symmetry can be set to point to any inertial direction. In particular, when the axis of symmetry is aligned with the Earth's spin axis, the J2 linear-dominant effect is identical for all the orbits. In this case, the J2 effect deforms the object shape while preserving the axial-symmetry.

  1. Coiling of elastic rods on rigid substrates

    PubMed Central

    Jawed, Mohammad K.; Da, Fang; Joo, Jungseock; Grinspun, Eitan; Reis, Pedro M.

    2014-01-01

    We investigate the deployment of a thin elastic rod onto a rigid substrate and study the resulting coiling patterns. In our approach, we combine precision model experiments, scaling analyses, and computer simulations toward developing predictive understanding of the coiling process. Both cases of deposition onto static and moving substrates are considered. We construct phase diagrams for the possible coiling patterns and characterize them as a function of the geometric and material properties of the rod, as well as the height and relative speeds of deployment. The modes selected and their characteristic length scales are found to arise from a complex interplay between gravitational, bending, and twisting energies of the rod, coupled to the geometric nonlinearities intrinsic to the large deformations. We give particular emphasis to the first sinusoidal mode of instability, which we find to be consistent with a Hopf bifurcation, and analyze the meandering wavelength and amplitude. Throughout, we systematically vary natural curvature of the rod as a control parameter, which has a qualitative and quantitative effect on the pattern formation, above a critical value that we determine. The universality conferred by the prominent role of geometry in the deformation modes of the rod suggests using the gained understanding as design guidelines, in the original applications that motivated the study. PMID:25267649

  2. The rigidity of three flavor quark matter

    SciTech Connect

    Sharma, Rishi; Mannarelli, Massimo

    2008-01-01

    Cold three flavor quark matter at large (but not asymptotically large) densities may exist in a crystalline color superconducting phase. These phases are characterized by a gap parameter {Delta} that varies periodieally in space, forming a crystal structure. A Ginzburg-Landau expansion in {Delta} shows that two crystal structures based on cubic symetry are particularly favorable, and may be the ground state of matter at densities present in neutron star cores. We derive the effective action for the phonon fields that describe space-and time-dependent fluctuations of the crystal structure formed by {Delta}, and obtain the shear modulus from the coefficients of the spatial derivative terms. Within a Ginzburg-Landau approximation, we find shear moduli which are 20 to 1000 times larger than those of neutron star crusts. This phase ofmatter is thus more rigid than any known material in the universe, but at the same time the crystalline color superconducting phase is also superftuid. These properties raise the possibility that the presence of this phase within neutron stars may have distinct implications for their phenomenology. For example, (some) pulsar glitches may originate in crystalline superconducting neutron star cores.

  3. Inflatable Tubular Structures Rigidized with Foams

    NASA Technical Reports Server (NTRS)

    Tinker, Michael L.; Schnell, Andrew R.

    2010-01-01

    Inflatable tubular structures that have annular cross sections rigidized with foams, and the means of erecting such structures in the field, are undergoing development. Although the development effort has focused on lightweight structural booms to be transported in compact form and deployed in outer space, the principles of design and fabrication are also potentially applicable to terrestrial structures, including components of ultralightweight aircraft, lightweight storage buildings and shelters, lightweight insulation, and sales displays. The use of foams to deploy and harden inflatable structures was first proposed as early as the 1960s, and has been investigated in recent years by NASA, the U.S. Air Force Research Laboratory, industry, and academia. In cases of deployable booms, most of the investigation in recent years has focused on solid cross sections, because they can be constructed relatively easily. However, solid-section foam-filled booms can be much too heavy for some applications. In contrast, booms with annular cross sections according to the present innovation can be tailored to obtain desired combinations of stiffness and weight through choice of diameters, wall thicknesses, and foam densities. By far the most compelling advantage afforded by this innovation is the possibility of drastically reducing weights while retaining or increasing the stiffnesses, relative to comparable booms that have solid foamfilled cross sections. A typical boom according to this innovation includes inner and outer polyimide film sleeves to contain foam that is injected between them during deployment.

  4. Rigid multipodal platforms for metal surfaces

    PubMed Central

    Valášek, Michal; Lindner, Marcin

    2016-01-01

    Summary In this review the recent progress in molecular platforms that form rigid and well-defined contact to a metal surface are discussed. Most of the presented examples have at least three anchoring units in order to control the spatial arrangement of the protruding molecular subunit. Another interesting feature is the lateral orientation of these foot structures which, depending on the particular application, is equally important as the spatial arrangement of the molecules. The numerous approaches towards assembling and organizing functional molecules into specific architectures on metal substrates are reviewed here. Particular attention is paid to variations of both, the core structures and the anchoring groups. Furthermore, the analytical methods enabling the investigation of individual molecules as well as monomolecular layers of ordered platform structures are summarized. The presented multipodal platforms bearing several anchoring groups form considerably more stable molecule–metal contacts than corresponding monopodal analogues and exhibit an enlarged separation of the functional molecules due to the increased footprint, as well as restrict tilting of the functional termini with respect to the metal surface. These platforms are thus ideally suited to tune important properties of the molecule–metal interface. On a single-molecule level, several of these platforms enable the control over the arrangement of the protruding rod-type molecular structures (e.g., molecular wires, switches, rotors, sensors) with respect to the surface of the substrate. PMID:27335731

  5. Kernel Non-Rigid Structure from Motion

    PubMed Central

    Gotardo, Paulo F. U.; Martinez, Aleix M.

    2013-01-01

    Non-rigid structure from motion (NRSFM) is a difficult, underconstrained problem in computer vision. The standard approach in NRSFM constrains 3D shape deformation using a linear combination of K basis shapes; the solution is then obtained as the low-rank factorization of an input observation matrix. An important but overlooked problem with this approach is that non-linear deformations are often observed; these deformations lead to a weakened low-rank constraint due to the need to use additional basis shapes to linearly model points that move along curves. Here, we demonstrate how the kernel trick can be applied in standard NRSFM. As a result, we model complex, deformable 3D shapes as the outputs of a non-linear mapping whose inputs are points within a low-dimensional shape space. This approach is flexible and can use different kernels to build different non-linear models. Using the kernel trick, our model complements the low-rank constraint by capturing non-linear relationships in the shape coefficients of the linear model. The net effect can be seen as using non-linear dimensionality reduction to further compress the (shape) space of possible solutions. PMID:24002226

  6. Heat transfer in suspensions of rigid particles

    NASA Astrophysics Data System (ADS)

    Brandt, Luca; Niazi Ardekani, Mehdi; Abouali, Omid

    2016-11-01

    We study the heat transfer in laminar Couette flow of suspensions of rigid neutrally buoyant particles by means of numerical simulations. An Immersed Boundary Method is coupled with a VOF approach to simulate the heat transfer in the fluid and solid phase, enabling us to fully resolve the heat diffusion. First, we consider spherical particles and show that the proposed algorithm is able to reproduce the correlations between heat flux across the channel, the particle volume fraction and the heat diffusivity obtained in laboratory experiments and recently proposed in the literature, results valid in the limit of vanishing inertia. We then investigate the role of inertia on the heat transfer and show an increase of the suspension diffusivity at finite particle Reynolds numbers. Finally, we vary the relativity diffusivity of the fluid and solid phase and investigate its effect on the effective heat flux across the channel. The data are analyzed by considering the ensemble averaged energy equation and decomposing the heat flux in 4 different contributions, related to diffusion in the solid and fluid phase, and the correlations between wall-normal velocity and temperature fluctuations. Results for non-spherical particles will be examined before the meeting. Supported by the European Research Council Grant No. ERC-2013- CoG-616186, TRITOS. The authors acknowledge computer time provided by SNIC (Swedish National Infrastructure for Computing).

  7. Flow past 2-D Hemispherical Rigid Canopies

    NASA Astrophysics Data System (ADS)

    Carnasciali, Maria-Isabel

    2013-11-01

    The flow past a 2-dimensional rigid hemispherical shape is investigated using PIV. Flow field measurements and images were generated with the use of a Thermoflow® apparatus. Results of this study are compared to prior work (APS DFD 2012 Session E9.00003) which employed CFD to investigate the flow in the near wake of hemispherical parachutes. The various sized gaps/open areas were positioned at distinct locations. The work presented here is part of a larger research project to investigate flow fields in deceleration devices and parachutes. Understanding the pitch-stability of parachutes is essential for accurate design and implementation of these deceleration devices but they present a difficult system to analyze. The flexibility of the parachute fabric results in large variations in the parachute geometry leading to complex fluid-structure interactions. Such flow, combined with flow through gaps and open areas, has been postulated to shed alternating vortices causing pitching/oscillations of the canopy. The results presented provide some insight into which geometric features affect vortex shedding and may enable the redesign of the baseline parachute to minimize instabilities.

  8. Modeling decomposition of rigid polyurethane foam

    SciTech Connect

    Hobbs, M.L.

    1998-01-01

    Rigid polyurethane foams are used as encapsulants to isolate and support thermally sensitive components within weapon systems. When exposed to abnormal thermal environments, such as fire, the polyurethane foam decomposes to form products having a wide distribution of molecular weights and can dominate the overall thermal response of the system. Decomposing foams have either been ignored by assuming the foam is not present, or have been empirically modeled by changing physical properties, such as thermal conductivity or emissivity, based on a prescribed decomposition temperature. The hypothesis addressed in the current work is that improved predictions of polyurethane foam degradation can be realized by using a more fundamental decomposition model based on chemical structure and vapor-liquid equilibrium, rather than merely fitting the data by changing physical properties at a prescribed decomposition temperature. The polyurethane decomposition model is founded on bond breaking of the primary polymer and formation of a secondary polymer which subsequently decomposes at high temperature. The bond breaking scheme is resolved using percolation theory to describe evolving polymer fragments. The polymer fragments vaporize according to individual vapor pressures. Kinetic parameters for the model were obtained from Thermal Gravimetric Analysis (TGA) from a single nonisothermal experiment with a heating rate of 20 C/min. Model predictions compare reasonably well with a separate nonisothermal TGA weight loss experiment with a heating rate of 200 C/min.

  9. Rigidity of microtubules is increased by stabilizing agents

    PubMed Central

    1995-01-01

    Microtubules are rigid polymers that contribute to the static mechanical properties of cells. Because microtubules are dynamic structures whose polymerization is regulated during changes in cell shape, we have asked whether the mechanical properties of microtubules might also be modulated. We measured the flexural rigidity, or bending stiffness, of individual microtubules under a number of different conditions that affect the stability of microtubules against depolymerization. The flexural rigidity of microtubules polymerized with the slowly hydrolyzable nucleotide analogue guanylyl-(alpha, beta)- methylene-diphosphonate was 62 +/- 9 x 10(-24) Nm2 (weighted mean +/- SEM); that of microtubules stabilized with tau protein was 34 +/- 3 x 10(-24) Nm2; and that of microtubules stabilized with the antimitotic drug taxol was 32 +/- 2 x 10(-24) Nm2. For comparison, microtubules that were capped to prevent depolymerization, but were not otherwise stabilized, had a flexural rigidity of 26 +/- 2 x 10(-24) Nm2. Decreasing the temperature from 37 degrees C to approximately 25 degrees C, a condition that makes microtubules less stable, decreased the stiffness of taxol-stabilized microtubules by one-third. We thus find that the more stable a microtubule, the higher its flexural rigidity. This raises the possibility that microtubule rigidity may be regulated in vivo. In addition, the high rigidity of an unstabilized, GDP-containing microtubule suggests that a large amount of energy could be stored as mechanical strain energy in the protein lattice for subsequent force generation during microtubule depolymerization. PMID:7642706

  10. Dynamic spindle reflexes and the rigidity of Parkinsonism.

    PubMed

    McLellan, D L

    1973-06-01

    The effects of stimulating the reflex arc from dynamic spindle endings were examined in patients with the rigidity of Parkinsonism and in control subjects. The arc was activated phasically by a tendon tap and by electrical stimulation in 15 patients. The effect of reinforcement by Jendrassik's manoeuvre was observed. The response to phasic activation indicated central facilitation of the reflex loop in the patients with Parkinsonism, with a concurrent decrease in fusimotor drive to dynamic spindles. These abnormalities could not be correlated with the severity of the patients' rigidity, and they did not alter when the rigidity was reduced by levodopa. The effect of activating dynamic spindle endings tonically by vibration at 50 Hz was also examined. The reflex contraction of the biceps and triceps muscles in response to vibration was found to be increased in 24 patients with rigidity compared with 24 control subjects. Patients with severe rigidity developed a more powerful contraction in response to vibration than patients with mild rigidity. The response to vibration was reduced by treatment with levodopa but the amount of this reduction could not be correlated with changes in the patients' rigidity.

  11. Acute rigid gas permeable contact lens intolerance.

    PubMed

    Jackson, A J; Wolsley, C; Briggs, J L; Frazer, D G

    2001-01-01

    Rigid gas permeable (RGP) and polymethylmethacrylate (PMMA) lens wearers occasionally report episodes of acute intolerance which is experienced upon lens insertion. In this paper, we report two cases of such intolerance in which the probable cause was contact lens inversion. We also present the results of a study in which a custom-built calibrated strain gauge was used to measure the force in Newtons (N), required to invert RGP lenses [oxygen permeability, or Dk, values between 30 and 90 x 10(-11) (cm2/s) (mlO2/ml x mmHg)] and PMMA lenses of different spherical back vertex powers (+/-3.00 D, 9.00 D). Significantly, less force was required to invert minus powered lenses (17.5 +/- 4.8 N) than plus powered lenses (31.7 +/- 7 .4 N), irrespective of the material. PMMA lenses required more force to induce inversion than that required to invert RGP lenses. Lenses with a Dk of 90 required only two thirds of the force (20.0 +/- 5.8 N) required to cause inversion compared to PMMA lenses (32.9 +/- 11.0 N). High powered PMMA lenses were found to be more likely to fracture on inversion than any other lenses tested. The force required to return negatively powered lenses to their original shape, once inverted, was less than 25% of that initially required to induce inversion. Plus powered lenses either reverted to their original form spontaneously, or required less than 3% of the original inversion force to do so. It was concluded that practitioners should consider inversion as a possible reason for otherwise unexplained, acute RGP contact lens intolerance experienced upon lens insertion. The reason why inversion has eluded so many, as a possible cause of intolerance, is likely to be because minimal force is required to return those lenses, which do not crack or fracture, to their original shape.

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

    PubMed Central

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

    2016-01-01

    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 αvβ3 or α5β1 integrins, we show that αVβ3 integrins permit the spreading of keratocytes but are not sufficient for polarization and rigidity sensing that require the engagement of α5β1 integrins. Our study demonstrates a matrix rigidity-dependent regulation of the directional persistence in motile keratocytes and refines the role of αvβ3 and α5β1 integrins in the molecular clutch model. PMID:27678055

  13. 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 αvβ3 or α5β1 integrins, we show that αVβ3 integrins permit the spreading of keratocytes but are not sufficient for polarization and rigidity sensing that require the engagement of α5β1 integrins. Our study demonstrates a matrix rigidity-dependent regulation of the directional persistence in motile keratocytes and refines the role of αvβ3 and α5β1 integrins in the molecular clutch model.

  14. Semi-Rigid Thoracoscopic Punch Biopsy Using a Hybrid Knife with a High-Pressure Water Jet for the Diagnosis of Pleural Effusions.

    PubMed

    Yin, Yan; Eberhardt, Ralf; Wang, Xiao-Bo; Wang, Qiu-Yue; Kang, Jian; Herth, Felix J F; Hou, Gang

    2016-01-01

    Semi-rigid thoracoscopy is an important technique in the definitive diagnosis of pleural diseases with high diagnostic sensitivity and specificity. Obtaining adequate samples from thickened pleura is the most important limitation of semi-rigid thoracoscopy with a standard flexible forceps (SFF) compared with rigid thoracoscopy, especially in patients with mesothelioma or benign fibrothorax. Developing a convenient, efficient and safe biopsy technique to obtain sufficient samples from such patients is a key topic in semi-rigid thoracoscopy. The hybrid knife (HK) is an innovative design fusing high-pressure water injection and a conventional diathermic knife that can allow for the safe resection of a larger lesion during gastrointestinal endoscopic dissection. Here, we describe 3 patients with unexplained pleural effusion who underwent pleural biopsy using an HK to investigate the potential use of the HK as a new pleural biopsy device in semi-rigid thoracoscopy when pleural lesions are difficult to biopsy using an SFF. The biopsies were obtained successfully by HK, and the diagnosis followed. The sizes of the biopsies collected by HK are larger than those collected by SFF. No complications were observed. Electrocautery biopsy using an HK during semi-rigid thoracoscopy has great potential for diagnosing consistent abnormal pleuras, which are difficult to biopsy with an SFF. © 2016 S. Karger AG, Basel.

  15. Quantification is Neither Necessary Nor Sufficient for Measurement

    NASA Astrophysics Data System (ADS)

    Mari, Luca; Maul, Andrew; Torres Irribarra, David; Wilson, Mark

    2013-09-01

    Being an infrastructural, widespread activity, measurement is laden with stereotypes. Some of these concern the role of measurement in the relation between quality and quantity. In particular, it is sometimes argued or assumed that quantification is necessary for measurement; it is also sometimes argued or assumed that quantification is sufficient for or synonymous with measurement. To assess the validity of these positions the concepts of measurement and quantitative evaluation should be independently defined and their relationship analyzed. We contend that the defining characteristic of measurement should be the structure of the process, not a feature of its results. Under this perspective, quantitative evaluation is neither sufficient nor necessary for measurement.

  16. Stochastic modeling of uncertain mass characteristics in rigid body dynamics

    NASA Astrophysics Data System (ADS)

    Richter, Lanae A.; Mignolet, Marc P.

    2017-03-01

    This paper focuses on the formulation, assessment, and application of a modeling strategy of uncertainty on the mass characteristics of rigid bodies, i.e. mass, position of center of mass, and inertia tensor. These characteristics are regrouped into a 4×4 matrix the elements of which are represented as random variables with joint probability density function derived following the maximum entropy framework. This stochastic model is first shown to satisfy all properties expected of the mass and tensor of inertia of rigid bodies. Its usefulness and computational efficiency are next demonstrated on the behavior of a rigid body in pure rotation exhibiting significant uncertainty in mass distribution.

  17. Fabrication of rigid microstructures with thiol-ene-based soft lithography for continuous-flow cell lysis.

    PubMed

    Burke, Jeffrey M; Pandit, Kunal R; Goertz, John P; White, Ian M

    2014-09-01

    In this work, we introduce a method for the soft-lithography-based fabrication of rigid microstructures and a new, simple bonding technique for use as a continuous-flow cell lysis device. While on-chip cell lysis techniques have been reported previously, these techniques generally require a long on-chip residence time, and thus cannot be performed in a rapid, continuous-flow manner. Microstructured microfluidic devices can perform mechanical lysis of cells, enabling continuous-flow lysis; however, rigid silicon-based devices require complex and expensive fabrication of each device, while polydimethylsiloxane (PMDS), the most common material used for soft lithography fabrication, is not rigid and expands under the pressures required, resulting in poor lysis performance. Here, we demonstrate the fabrication of microfluidic microstructures from off-stoichiometry thiol-ene (OSTE) polymer using soft-lithography replica molding combined with a post-assembly cure for easy bonding. With finite element simulations, we show that the rigid microstructures generate an energy dissipation rate of nearly 10(7), which is sufficient for continuous-flow cell lysis. Correspondingly, with the OSTE device we achieve lysis of highly deformable MDA-MB-231 breast cancer cells at a rate of 85%, while a comparable PDMS device leads to a lysis rate of only 40%.

  18. Comparative costs of flexible package cells and rigid cells for lithium-ionhybrid electric vehicle batteries.

    SciTech Connect

    Nelson, P. A.; Jansen, A. N.

    2006-11-28

    We conducted a design study to compare the manufacturing costs at a level of 100,000 hybrid vehicle batteries per year for flexible package (Flex) cells and for rigid aluminum container (Rigid) cells. Initially, the Rigid cells were considered to have welded closures and to be deep-drawn containers of about the same shape as the Flex cells. As the study progressed, the method of fabricating and sealing the Rigid cells was expanded to include lower cost options including double seaming and other mechanically fastened closures with polymer sealants. Both types of batteries were designed with positive electrodes containing Li(Ni{sub 1/3}Co{sub 1/3}Mn{sub 1/3})O{sub 2} and graphite negative electrodes. The use of a different combination of lithium-ion electrodes would have little effect on the difference in costs for the two types of cells. We found that 20-Ah cells could be designed with excellent performance and heat rejection capabilities for either type of cell. Many parts in the design of the Flex cells are identical or nearly identical to those of the Rigid Cell, so for these features there would be no difference in the cost of manufacturing the two types of batteries. We judged the performance, size and weight of the batteries to be sufficiently similar that the batteries would have the same value for their application. Some of the design features of the Flex cells were markedly different than those of the deep-drawn and welded Rigid cells and would result in significant cost savings. Fabrication and processing steps for which the Flex cells appear to have a cost advantage over these Rigid cells are (1) container fabrication and sealing, (2) terminal fabrication and sealing, and (3) intercell connections. The costs of providing cooling channels adjacent to the cells and for module and battery hardware appear to favor Rigid cell batteries slightly. Overall, Flex cell batteries appear to have an advantage of about $1.20-$3.70 per cell for a 25-kW Battery of 20

  19. Optimisation of grolishing freeform surfaces with rigid and semi-rigid tools

    NASA Astrophysics Data System (ADS)

    Yu, Guoyu; Wu, Hsing-Yu; Walker, David; Zheng, Xiao; Li, Hongyu; Dunn, Christina; Gray, Caroline

    2016-07-01

    After the formal acceptance of our fabrication of E-ELT segments, we aim to further accelerate the mass production by introducing an intermediate grolishing procedure using industrial robots, reducing the total process time by this much faster and parallel link. In this paper, we have presented research outputs on tool design, tool path generation, study of mismatch between rigid, semi-rigid tool and aspheric surface. It is indicated that the generation of mid-spatial frequency is proportional to the grit size and misfit between work piece and tool surfaces. Using a Non-Newtonian material tool with a spindle speed of 30 rpm has successfully reduce the mid-spatial error. The optimization of process parameters involve the study the combination effects of the above factors. These optimized parameters will result in a lookup table for reference of given input surface quality. Future work may include the higher spindle speed for grolishing with non- Newtonian tool looking for potential applications regarding to form correction, higher removal rate and edge control.

  20. Liquid sloshing in rigid cylindrical container with multiple rigid annular baffles: Free vibration

    NASA Astrophysics Data System (ADS)

    Wang, J. D.; Lo, S. H.; Zhou, D.

    2012-10-01

    A semi-analytical approach is presented to obtain the natural frequencies and vibration modes of ideal liquid sloshing in a rigid partially liquid-filled cylindrical container with multiple rigid annular baffles of the same inner radius. The complicated liquid domain is divided into several simple sub-domains so that the liquid velocity potential in each liquid sub-domain is of class C1 with continuity boundary conditions. Based on the superposition principle, the analytical solutions of the liquid velocity potential corresponding to each liquid sub-domain are obtained by means of the method of separation of variables. The eigenfrequency equation is obtained by expanding the free surface condition and the artificial interface conditions into the Fourier series in the liquid height direction and the Bessel series in the radial direction. Stable and fast numerical computations are observed by the convergence study. Excellent agreements have been achieved in the comparison of results obtained by the proposed approach with those given by finite element software ADINA. The natural frequencies and mode shapes versus the position, the inner radius and the number of the annular baffles are discussed in detail.

  1. Minimal sufficient statistical experiments on von Neumann algebras

    NASA Astrophysics Data System (ADS)

    Kuramochi, Yui

    2017-06-01

    A statistical experiment on a von Neumann algebra is a parametrized family of normal states on the algebra. This paper introduces the concept of minimal sufficiency for statistical experiments in such operator algebraic situations. We define equivalence relations of statistical experiments indexed by a common parameter set by completely positive or Schwarz coarse-graining and show that any statistical experiment is equivalent to a minimal sufficient statistical experiment unique up to normal isomorphism of outcome algebras. We also establish the relationship between the minimal sufficiency condition for a statistical experiment in this paper and those for subalgebra. These concepts and results are applied to the concatenation relation for completely positive channels with general input and outcome von Neumann algebras. In the case of the quantum-classical channel corresponding to the positive-operator valued measure (POVM), we prove the equivalence of the minimal sufficient condition previously proposed by the author and that in this paper. We also give a characterization of the discreteness of a POVM up to postprocessing equivalence in terms of the corresponding quantum-classical channel.

  2. Leadership, the Logic of Sufficiency and the Sustainability of Education

    ERIC Educational Resources Information Center

    Bottery, Mike

    2012-01-01

    The notion of sufficiency has not yet entered mainstream educational thinking, and it still has to make its mark upon educational leadership. However, a number of related concepts--particularly those of sustainability and complexity theory--are beginning to be noticed. This article examines these two concepts and uses them to critique the…

  3. The Indochinese in America: Progress Towards Self Sufficiency.

    ERIC Educational Resources Information Center

    Finck, John

    Despite suspicion in some quarters that refugee resettlement has been unduly expensive, evidence indicates that the Indochinese have made steady progress toward self-sufficiency. The majority of Hmong refugees in Providence, Rhode Island, for example, which has been "heavily impacted" by the large number of Indochinese who have become…

  4. Intellectual Freedom and Economic Sufficiency as Educational Entitlements.

    ERIC Educational Resources Information Center

    Morse, Jane Fowler

    2001-01-01

    Using the theories of John Stuart Mill and Karl Marx, this article supports the educational entitlements of intellectual freedom and economic sufficiency. Explores these issues in reference to their implications for teaching, the teaching profession and its training. Concludes that ideas cannot be controlled by the interests of the dominant class.…

  5. Necessary and sufficient elastic stability conditions in various crystal systems

    NASA Astrophysics Data System (ADS)

    Mouhat, Félix; Coudert, François-Xavier

    2014-12-01

    While the Born elastic stability criteria are well known for cubic crystals, there is some confusion in the literature about the form they should take for lower-symmetry crystal classes. Here we present closed form necessary and sufficient conditions for elastic stability in all crystal classes, as a concise and pedagogical reference to stability criteria in noncubic materials.

  6. Leadership, the Logic of Sufficiency and the Sustainability of Education

    ERIC Educational Resources Information Center

    Bottery, Mike

    2012-01-01

    The notion of sufficiency has not yet entered mainstream educational thinking, and it still has to make its mark upon educational leadership. However, a number of related concepts--particularly those of sustainability and complexity theory--are beginning to be noticed. This article examines these two concepts and uses them to critique the…

  7. 39 CFR 3030.20 - Sufficiency of information.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Sufficiency of information. 3030.20 Section 3030.20 Postal Service POSTAL REGULATORY COMMISSION PERSONNEL RULES FOR COMPLAINTS Supplemental..., either require the complainant and/or the Postal Service to provide additional information as deemed...

  8. Towards a Sufficient Theory of Transition in Cognitive Development.

    ERIC Educational Resources Information Center

    Wallace, J. G.

    The work reported aims at the construction of a sufficient theory of transition in cognitive development. The method of theory construction employed is computer simulation of cognitive process. The core of the model of transition presented comprises self-modification processes that, as a result of continuously monitoring an exhaustive record of…

  9. Intellectual Freedom and Economic Sufficiency as Educational Entitlements.

    ERIC Educational Resources Information Center

    Morse, Jane Fowler

    2001-01-01

    Using the theories of John Stuart Mill and Karl Marx, this article supports the educational entitlements of intellectual freedom and economic sufficiency. Explores these issues in reference to their implications for teaching, the teaching profession and its training. Concludes that ideas cannot be controlled by the interests of the dominant class.…

  10. 19 CFR 351.203 - Determination of sufficiency of petition.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 3 2011-04-01 2011-04-01 false Determination of sufficiency of petition. 351.203 Section 351.203 Customs Duties INTERNATIONAL TRADE ADMINISTRATION, DEPARTMENT OF COMMERCE ANTIDUMPING AND... the Act, unless such domestic producer demonstrates to the Secretary's satisfaction that its...

  11. Online Learning in Higher Education: Necessary and Sufficient Conditions

    ERIC Educational Resources Information Center

    Lim, Cher Ping

    2005-01-01

    The spectacular development of information and communication technologies through the Internet has provided opportunities for students to explore the virtual world of information. In this article, the author discusses the necessary and sufficient conditions for successful online learning in educational institutions. The necessary conditions…

  12. Increasing urban water self-sufficiency: new era, new challenges.

    PubMed

    Rygaard, Martin; Binning, Philip J; Albrechtsen, Hans-Jørgen

    2011-01-01

    Urban water supplies are traditionally based on limited freshwater resources located outside the cities. However, a range of concepts and techniques to exploit alternative water resources has gained ground as water demands begin to exceed the freshwater available to cities. Based on 113 cases and 15 in-depth case studies, solutions used to increase water self-sufficiency in urban areas are analyzed. The main drivers for increased self-sufficiency were identified to be direct and indirect lack of water, constrained infrastructure, high quality water demands and commercial and institutional pressures. Case studies demonstrate increases in self-sufficiency ratios to as much as 80% with contributions from recycled water, seawater desalination and rainwater collection. The introduction of alternative water resources raises several challenges: energy requirements vary by more than a factor of ten amongst the alternative techniques, wastewater reclamation can lead to the appearance of trace contaminants in drinking water, and changes to the drinking water system can meet tough resistance from the public. Public water-supply managers aim to achieve a high level of reliability and stability. We conclude that despite the challenges, self-sufficiency concepts in combination with conventional water resources are already helping to reach this goal.

  13. Is the Supply of Mathematics and Science Teachers Sufficient?

    ERIC Educational Resources Information Center

    Ingersoll, Richard M.; Perda, David

    2010-01-01

    This study seeks to empirically ground the debate over mathematics and science teacher shortages and evaluate the extent to which there is, or is not, sufficient supply of teachers in these fields. The authors' analyses of nationally representative data from multiple sources show that math and science are the fields most difficult to staff, but…

  14. 24 CFR 242.2 - Program financial self-sufficiency.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... HOUSING AND URBAN DEVELOPMENT MORTGAGE AND LOAN INSURANCE PROGRAMS UNDER NATIONAL HOUSING ACT AND OTHER AUTHORITIES MORTGAGE INSURANCE FOR HOSPITALS General Eligibility Requirements § 242.2 Program financial self... self-sufficiency and actuarial soundness; i.e., to avoid mortgage defaults and claims for insurance...

  15. Test-Taking Strategies and the Self-Sufficient Learner.

    ERIC Educational Resources Information Center

    Annis, Linda Ferrill

    This paper outlines recommended test-taking strategies for the self-sufficient learner based on research in cognitive psychology. The theoretical model used is the information-processing approach involving the three essential steps of paying attention, encoding, and framing associative linkages for the new material. Preparing for examinations is…

  16. Necessary and Sufficient Condition for Quantum State-Independent Contextuality.

    PubMed

    Cabello, Adán; Kleinmann, Matthias; Budroni, Costantino

    2015-06-26

    We solve the problem of whether a set of quantum tests reveals state-independent contextuality and use this result to identify the simplest set of the minimal dimension. We also show that identifying state-independent contextuality graphs [R. Ramanathan and P. Horodecki, Phys. Rev. Lett. 112, 040404 (2014)] is not sufficient for revealing state-independent contextuality.

  17. 40 CFR 350.13 - Sufficiency of assertions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Section 350.13 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SUPERFUND, EMERGENCY... discoverable through reverse engineering. To support this conclusion, the facts asserted must show that... environmental releases. (b) The sufficiency of the trade secrecy claim shall be decided entirely upon the...

  18. 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

  19. An Inexpensive Torsional Pendulum Apparatus for Rigidity Modulus Measurement.

    ERIC Educational Resources Information Center

    Tyagi, S.; Lord, A. E., Jr.

    1979-01-01

    Described is an easy to assemble, and inexpensive, torsional pendulum which gives an accuracy of measurement of the modulus of rigidity, G, comparable to the accuracy obtained with the more expensive commercially available student models. (Author/GA)

  20. Flash-fire propensity of rigid foam insulation

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Murphy, R. M.

    1978-01-01

    Twelve samples of rigid foam insulation were evaluated for flash-fire propensity, using the USF flash-fire screening test method. These materials exhibited little or no flash-fire propensity under these particular test conditions.

  1. New design concepts for permeable rigid contact lenses.

    PubMed

    Williams, C E

    1979-03-01

    Gas permeable rigid lens materials offer the opportunity to reevaluate contact lens design. This paper presents the rationale and procedures followed in the development of a design concept for the Polycon lens material.

  2. The role of rigidity in controlling material failure

    NASA Astrophysics Data System (ADS)

    Driscoll, Michelle M.; Gin-ge Chen, Bryan; Beuman, Thomas H.; Ulrich, Stephan; Nagel, Sidney R.; Vitelli, Vincenzo

    2016-09-01

    We investigate how material rigidity acts as a key control parameter for the failure of solids under stress. In both experiments and simulations, we demonstrate that material failure can be continuously tuned by varying the underlying rigidity of the material while holding the amount of disorder constant. As the rigidity transition is approached, failure due to the application of uniaxial stress evolves from brittle cracking to system-spanning diffuse breaking. This evolution in failure behavior can be parameterized by the width of the crack. As a system becomes more and more floppy, this crack width increases until it saturates at the system size. Thus, the spatial extent of the failure zone can be used as a direct probe for material rigidity.

  3. The role of rigidity in controlling material failure

    PubMed Central

    Driscoll, Michelle M.; Chen, Bryan Gin-ge; Beuman, Thomas H.; Ulrich, Stephan; Nagel, Sidney R.; Vitelli, Vincenzo

    2016-01-01

    We investigate how material rigidity acts as a key control parameter for the failure of solids under stress. In both experiments and simulations, we demonstrate that material failure can be continuously tuned by varying the underlying rigidity of the material while holding the amount of disorder constant. As the rigidity transition is approached, failure due to the application of uniaxial stress evolves from brittle cracking to system-spanning diffuse breaking. This evolution in failure behavior can be parameterized by the width of the crack. As a system becomes more and more floppy, this crack width increases until it saturates at the system size. Thus, the spatial extent of the failure zone can be used as a direct probe for material rigidity. PMID:27621463

  4. Adaptivity demonstration of inflatable rigidized integrated structures (IRIS)

    NASA Astrophysics Data System (ADS)

    Natori, M. C.; Higuchi, Ken; Sekine, Koji; Okazaki, Kakuma

    1995-10-01

    An inflatable rigidized integrated structure (IRIS), which is composed of membrane elements and cable networks, and whose structural accuracy is decided by mainly cable networks, has various design adaptivity, since it is a high performance deployable structure for future space applications. In order to keep some stiffness after deployment, materials of membrane are assumed to be rigidized in space, and sometimes the cable network is also rigidized. The concept can cover various structural elements and structure systems. The accuracy analysis of reflector surface constrained by inside hard points and the manufacturing of a simple reflector model is introduced. Test results of rigidized cable columns to show many variations of IRIS to be feasible are also reported.

  5. Detail, north span, from east, showing concrete "rainbow" arch rigidly ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail, north span, from east, showing concrete "rainbow" arch rigidly fixed at center pier and north abutment, and hangers linking arch rib and bridge deck - Horner Street Bridge, Horner Street over Stonycreek River, Johnstown, Cambria County, PA

  6. Rigid polyvinyl chloride/wood-flour composites and their foams

    NASA Astrophysics Data System (ADS)

    Mengeloglu, Fatih

    The effects of impact modifier types (crosslinked vs. uncrosslinked) and addition levels on the mechanical properties of rigid PVC/wood-fiber composites were examined. With the proper choice of modifier type and concentration, the impact strength of rigid PVC/wood-fiber composites can be significantly improved without degrading the tensile properties. Foaming is an effective method for reducing the density and brittleness of polymers. The experimental results indicated that impact modification (crosslinked and uncrosslinked modifiers) accelerated the rate of gas loss during foaming process, which impeded the growth of nucleated cells. Consequently, impact modifiers are an unnecessary ingredient in the formulation of foamed neat rigid PVC and rigid PVC/wood-flour composites. Since the batch foaming process used to generate cellular foamed structures in the composites is not likely to be implemented in the industrial production of foams because it is not cost-effective, the manufacture of PVC/wood-flour composite foams in an extrusion process needs to be investigated. The foamability of rigid PVC/wood-flour composites using moisture present in the wood flour as the foaming agent was investigated using a central composite design (CCD) experiment. It was determined that wood flour moisture could be used effectively as the foaming agent in the production of rigid PVC/wood-flour composite foams. Finally, mechanical property characterizations of extrusion-foamed rigid PVC/wood-flour composites were done. Extrusion foaming reduced the density and the brittleness of the composites, but also caused a reduction in the tensile strength and modulus of the rigid PVC/wood-flour composites. This study suggested that depending on the application, the problems associated with the rigid PVC/wood-flour composite products; high density, brittleness and low impact resistance can be overcome by adopting impact modification and/or extrusion foaming. Since impact modification improves the

  7. 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.

  8. Synthesis of giant rigid pi-conjugated dendrimers.

    PubMed

    Jiang, Yang; Lu, Yi-Xuan; Cui, Yu-Xin; Zhou, Qi-Feng; Ma, Yuguo; Pei, Jian

    2007-10-25

    A novel family of giant pi-conjugated dendrimers (G0, G1, and G2) solely constructed by 5,5,10,10,15,15-hexahexyltruxene units has been developed in a convergent manner through a Suzuki cross-coupling reaction. The overall yields to such large rigid conjugated dendrimers are quite satisfying. The structures and purity of these nanosize rigid dendrimers are verified by 1H and 13C NMR, MALDI-TOF MS, and elemental analysis.

  9. Rigid fire-resistant foams for walls and floors

    NASA Technical Reports Server (NTRS)

    Gagliani, J.; Lee, R.; Sorathia, U. A. K.; Wilcoxson, A. L.

    1981-01-01

    Previous techniques for fabricating rigid fire-resistant polyimide foams by compressing already-foamed precursor have been supplanted by one-step constrained-rise process. Precursor mixed with reinforcing fillers is placed between rigid substrates that constrain expansion of foam as it is heated by microwave energy. Process works for both liquid and powder precursors and can also be adapted to attach woven fiberglass skins at same time prcursor is being foamed.

  10. Rigid fire-resistant foams for walls and floors

    NASA Technical Reports Server (NTRS)

    Gagliani, J.; Lee, R.; Sorathia, U. A. K.; Wilcoxson, A. L.

    1981-01-01

    Previous techniques for fabricating rigid fire-resistant polyimide foams by compressing already-foamed precursor have been supplanted by one-step constrained-rise process. Precursor mixed with reinforcing fillers is placed between rigid substrates that constrain expansion of foam as it is heated by microwave energy. Process works for both liquid and powder precursors and can also be adapted to attach woven fiberglass skins at same time prcursor is being foamed.

  11. Stochastic finite element applications in rigid pavement performance

    NASA Astrophysics Data System (ADS)

    Attoh-Okine, Nii O.

    1999-05-01

    Rigid pavement structures have uncertainties and variability in their structural layers and components. These variations and uncertainties are seldomly included in performance assessment and evaluation in pavement systems. This paper proposes to use Stochastic Finite Element Method (SFEM) in rigid pavement faulting and load transfer efficiency. The SFEM uses random parameters, as stochastic process namely random fields. These random fields are characterized, quantitatively by spatial functions of statistical moment like the mean, variance and covariance.

  12. Modeling the Collision with Friction of Rigid Bodies

    NASA Astrophysics Data System (ADS)

    Zabuga, A. G.

    2016-09-01

    Different models of a perfectly inelastic collision of rigid bodies in plane motion are compared. Formulas for the impact impulses are derived for the Kane-Levinson-Whittaker model based on the kinematic restitution factor, the Routh model based on the kinetic restitution factor, and the Stronge model based on the energy restitution factor. It is shown that these formulas coincide if the collision of rough rigid bodies in plane motion is perfectly inelastic

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

    PubMed

    Izutani, Hironori; Nakamura, Teruya; Kawachi, Kanji

    2010-12-31

    We review and compare our experience with tricuspid ring annuloplasty between usage of the Cosgrove-Edwards flexible band and the MC(3) 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.

  14. Rigid-motion-invariant classification of 3-D textures.

    PubMed

    Jain, Saurabh; Papadakis, Manos; Upadhyay, Sanat; Azencott, Robert

    2012-05-01

    This paper studies the problem of 3-D rigid-motion-invariant texture discrimination for discrete 3-D textures that are spatially homogeneous by modeling them as stationary Gaussian random fields. The latter property and our formulation of a 3-D rigid motion of a texture reduce the problem to the study of 3-D rotations of discrete textures. We formally develop the concept of 3-D texture rotations in the 3-D digital domain. We use this novel concept to define a "distance" between 3-D textures that remains invariant under all 3-D rigid motions of the texture. This concept of "distance" can be used for a monoscale or a multiscale 3-D rigid-motion-invariant testing of the statistical similarity of the 3-D textures. To compute the "distance" between any two rotations R(1) and R(2) of two given 3-D textures, we use the Kullback-Leibler divergence between 3-D Gaussian Markov random fields fitted to the rotated texture data. Then, the 3-D rigid-motion-invariant texture distance is the integral average, with respect to the Haar measure of the group SO(3), of all of these divergences when rotations R(1) and R(2) vary throughout SO(3). We also present an algorithm enabling the computation of the proposed 3-D rigid-motion-invariant texture distance as well as rules for 3-D rigid-motion-invariant texture discrimination/classification and experimental results demonstrating the capabilities of the proposed 3-D rigid-motion texture discrimination rules when applied in a multiscale setting, even on very general 3-D texture models.

  15. Irreversible Enthalpic Relaxation of Rigid Amorphous Fraction in Isotactic Polystyrene

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Cebe, Peggy

    2004-03-01

    The crystalline, rigid amorphous, and mobile amorphous fractions in isotactic polystyrene (iPS) were studied using: 1. quasi-isothermal temperature-modulated differential scanning calorimetry (TMDSC) (i.e., with step-wise increase of temperature), and 2. regular TMDSC (i.e., with constant rate of temperature increase). The crystal fraction was determined from wide angle X-ray scattering and endotherm analysis; mobile amorphous fraction was determined from heat capacity measurements at the glass transition. The validity of a three-phase model for iPS (comprising crystals, mobile and rigid amorphous fractions) is confirmed by heat capacity measurements made during quasi-isothermal cold crystallization. At the same time, we prove the rigid amorphous fraction to be established at the crystallization temperature and not during subsequent cooling. The rigid amorphous fraction is thus stable below the crystallization temperature Tc, and relaxes at a temperature Ta, between Tc and the melting point of the lowest melting crystals. Upon relaxing, the rigid amorphous fraction undergoes a phase transition to mobile amorphous fraction. For cold-crystallized iPS the relaxation of the rigid amorphous fraction is found to be an enthalpy involved, non-reversible relaxation occurring before the melting of the crystals.

  16. Non-rigid registration using higher-order mutual information

    NASA Astrophysics Data System (ADS)

    Rueckert, D.; Clarkson, M. J.; Hill, D. L. G.; Hawkes, D. J.

    2000-03-01

    Non-rigid registration of multi-modality images is an important tool for assessing temporal and structural changesbetween images. For rigid registration, voxel similarity measures like mutual information have been shown to alignimages from different modalities accurately and robustly. For non-rigid registration, mutual information can besensitive to local variations of intensity which in MR images may be caused by RF inhomogeneity. The reasonfor the sensitivity of mutual information towards intensity variations stems from the fact that mutual informationignores any spatial information. In this paper we propose an extension of the mutual information framework whichincorporates spatial information about higher-order image structure into the registration process and has the potentialto improve the accuracy and robustness of non-rigid registration in the presence of intensity variations. We haveapplied the non-rigid registration algorithm to a number of simulated MR brain images of a digital phantom whichhave been degraded by a simulated intensity shading and a known deformation. In addition, we have applied thealgorithm for the non-rigid registration of eight pre- and post-operative brain MR images which were acquired withan interventional MR scanner and therefore have substantial intensity shading due to RF field inhomogeneities. Inall cases the second-order estimate of mutual information leads to robust and accurate registration.

  17. The coupling VIV analysis of SCRs with rigid swing

    NASA Astrophysics Data System (ADS)

    Liu, Juan; Huang, Weiping

    2015-08-01

    With the development of deepwater oil and gas exploration, Steel Catenary Risers (SCRs) become preferred risers for resource production, import and export. Vortex induced vibration (VIV) is the key problem encountered in the design of SCRs. In this study, a new model, the rigid swing model, is proposed based on the consideration of large curvature of SCRs. The sag bend of SCRs is assumed as a rigid swing system around the axis from the hanging point to the touch down point (TDP) in the model. The torque, produced by the lift force and the swing vector, provides the driving torque for the swing system, and the weight of SCRs provides the restoring torque. The simulated response of rigid swing is coupled with bending vibration, and then the coupling VIV model of SCRs is studied in consideration of bending vibration and rigid motion. The calculated results indicate that the rigid swing has a magnitude equal to that of bending vibration, and the rigid motion affects the dynamic response of SCRs and can not be neglected in the VIV analysis.

  18. Retinal flow is sufficient for steering during observer rotation

    NASA Technical Reports Server (NTRS)

    Li, Li; Warren, William H Jr

    2002-01-01

    How do people control locomotion while their eyes are simultaneously rotating? A previous study found that during simulated rotation, they can perceive a straight path of self-motion from the retinal flow pattern, despite conflicting extraretinal information, on the basis of dense motion parallax and reference objects. Here we report that the same information is sufficient for active control ofjoystick steering. Participants steered toward a target in displays that simulated a pursuit eye movement. Steering was highly inaccurate with a textured ground plane (motion parallax alone), but quite accurate when an array of posts was added (motion parallax plus reference objects). This result is consistent with the theory that instantaneous heading is determined from motion parallax, and the path of self-motion is determined by updating heading relative to environmental objects. Retinal flow is thus sufficient for both perceiving self-motion and controlling self-motion with a joystick; extraretinal and positional information can also contribute, but are not necessary.

  19. Efficiency, sufficiency, and recent change in Newfoundland subsistence horticulture

    SciTech Connect

    Omohundro, J.T.

    1986-09-01

    Traditional Newfoundland horticulture has been a subordinate and compensatory element of the subsistence sphere in a plural economy centered on fishing. Criticized as inefficient and ruinous to the land, this tuber-rootbrassica gardening has in fact been a valuable contribution to diet, is relatively efficient, and compensates for the inadequacies of land and weather. Field data from the Great Northern Peninsula, where some traditional practices persist, demonstrate that the practices conserve time and labor, and substitute massive applications of materials to assure a yield sufficient for household needs. The inefficiency in the tradition may be understood as a response to the constraints upon household labor and follows a kind of Leibig's law of the minimum. Recent changes in gardening practices reveal the dynamics of horticulture in the household's mixed economic strategy. As cash and land have become more common, they have been used to further reduce time while maintaining sufficiency.

  20. Entrepreneurship by any other name: self-sufficiency versus innovation.

    PubMed

    Parker Harris, Sarah; Caldwell, Kate; Renko, Maija

    2014-01-01

    Entrepreneurship has been promoted as an innovative strategy to address the employment of people with disabilities. Research has predominantly focused on the self-sufficiency aspect without fully integrating entrepreneurship literature in the areas of theory, systems change, and demonstration projects. Subsequently there are gaps in services, policies, and research in this field that, in turn, have limited our understanding of the support needs and barriers or facilitators of entrepreneurs with disabilities. A thorough analysis of the literature in these areas led to the development of two core concepts that need to be addressed in integrating entrepreneurship into disability employment research and policy: clarity in operational definitions and better disability statistics and outcome measures. This article interrogates existing research and policy efforts in this regard to argue for a necessary shift in the field from focusing on entrepreneurship as self-sufficiency to understanding entrepreneurship as innovation.

  1. Retinal flow is sufficient for steering during observer rotation

    NASA Technical Reports Server (NTRS)

    Li, Li; Warren, William H Jr

    2002-01-01

    How do people control locomotion while their eyes are simultaneously rotating? A previous study found that during simulated rotation, they can perceive a straight path of self-motion from the retinal flow pattern, despite conflicting extraretinal information, on the basis of dense motion parallax and reference objects. Here we report that the same information is sufficient for active control ofjoystick steering. Participants steered toward a target in displays that simulated a pursuit eye movement. Steering was highly inaccurate with a textured ground plane (motion parallax alone), but quite accurate when an array of posts was added (motion parallax plus reference objects). This result is consistent with the theory that instantaneous heading is determined from motion parallax, and the path of self-motion is determined by updating heading relative to environmental objects. Retinal flow is thus sufficient for both perceiving self-motion and controlling self-motion with a joystick; extraretinal and positional information can also contribute, but are not necessary.

  2. 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).

  3. Predictive sufficiency and the use of stored internal state

    NASA Technical Reports Server (NTRS)

    Musliner, David J.; Durfee, Edmund H.; Shin, Kang G.

    1994-01-01

    In all embedded computing systems, some delay exists between sensing and acting. By choosing an action based on sensed data, a system is essentially predicting that there will be no significant changes in the world during this delay. However, the dynamic and uncertain nature of the real world can make these predictions incorrect, and thus, a system may execute inappropriate actions. Making systems more reactive by decreasing the gap between sensing and action leaves less time for predictions to err, but still provides no principled assurance that they will be correct. Using the concept of predictive sufficiency described in this paper, a system can prove that its predictions are valid, and that it will never execute inappropriate actions. In the context of our CIRCA system, we also show how predictive sufficiency allows a system to guarantee worst-case response times to changes in its environment. Using predictive sufficiency, CIRCA is able to build real-time reactive control plans which provide a sound basis for performance guarantees that are unavailable with other reactive systems.

  4. Sufficient dimension reduction via squared-loss mutual information estimation.

    PubMed

    Suzuki, Taiji; Sugiyama, Masashi

    2013-03-01

    The goal of sufficient dimension reduction in supervised learning is to find the low-dimensional subspace of input features that contains all of the information about the output values that the input features possess. In this letter, we propose a novel sufficient dimension-reduction method using a squared-loss variant of mutual information as a dependency measure. We apply a density-ratio estimator for approximating squared-loss mutual information that is formulated as a minimum contrast estimator on parametric or nonparametric models. Since cross-validation is available for choosing an appropriate model, our method does not require any prespecified structure on the underlying distributions. We elucidate the asymptotic bias of our estimator on parametric models and the asymptotic convergence rate on nonparametric models. The convergence analysis utilizes the uniform tail-bound of a U-process, and the convergence rate is characterized by the bracketing entropy of the model. We then develop a natural gradient algorithm on the Grassmann manifold for sufficient subspace search. The analytic formula of our estimator allows us to compute the gradient efficiently. Numerical experiments show that the proposed method compares favorably with existing dimension-reduction approaches on artificial and benchmark data sets.

  5. Molecular Rigidity in Dry and Hydrated Onion Cell Walls.

    PubMed

    Ha, M. A.; Apperley, D. C.; Jarvis, M. C.

    1997-10-01

    Solid-state nuclear magnetic resonance relaxation experiments can provide information on the rigidity of individual molecules within a complex structure such as a cell wall, and thus show how each polymer can potentially contribute to the rigidity of the whole structure. We measured the proton magnetic relaxation parameters T2 (spin-spin) and T1p (spin-lattice) through the 13C-nuclear magnetic resonance spectra of dry and hydrated cell walls from onion (Allium cepa L.) bulbs. Dry cell walls behaved as rigid solids. The form of their T2 decay curves varied on a continuum between Gaussian, as in crystalline solids, and exponential, as in more mobile materials. The degree of molecular mobility that could be inferred from the T2 and T1p decay patterns was consistent with a crystalline state for cellulose and a glassy state for dry pectins. The theory of composite materials may be applied to explain the rigidity of dry onion cell walls in terms of their components. Hydration made little difference to the rigidity of cellulose and most of the xyloglucan shared this rigidity, but the pectic fraction became much more mobile. Therefore, the cellulose/xyloglucan microfibrils behaved as solid rods, and the most significant physical distinction within the hydrated cell wall was between the microfibrils and the predominantly pectic matrix. A minor xyloglucan fraction was much more mobile than the microfibrils and probably corresponded to cross-links between them. Away from the microfibrils, pectins expanded upon hydration into a nonhomogeneous, but much softer, almost-liquid gel. These data are consistent with a model for the stress-bearing hydrated cell wall in which pectins provide limited stiffness across the thickness of the wall, whereas the cross-linked microfibril network provides much greater rigidity in other directions.

  6. Applying a potential across a biomembrane: electrostatic contribution to the bending rigidity and membrane instability.

    PubMed

    Ambjörnsson, Tobias; Lomholt, Michael A; Hansen, Per Lyngs

    2007-05-01

    We investigate the effect on biomembrane mechanical properties due to the presence an external potential for a nonconductive incompressible membrane surrounded by different electrolytes. By solving the Debye-Hückel and Laplace equations for the electrostatic potential and using the relevant stress-tensor we find (1) in the small screening length limit, where the Debye screening length is smaller than the distance between the electrodes, the screening certifies that all electrostatic interactions are short range and the major effect of the applied potential is to decrease the membrane tension and increase the bending rigidity; explicit expressions for electrostatic contribution to the tension and bending rigidity are derived as a function of the applied potential, the Debye screening lengths, and the dielectric constants of the membrane and the solvents. For sufficiently large voltages the negative contribution to the tension is expected to cause a membrane stretching instability. (2) For the dielectric limit, i.e., no salt (and small wave vectors compared to the distance between the electrodes), when the dielectric constant on the two sides are different the applied potential induces an effective (unscreened) membrane charge density, whose long-range interaction is expected to lead to a membrane undulation instability.

  7. Theoretical evaluation of rigid baffles in the 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. This analysis employs both two and three dimensional combustor models characterized by concentrated combustion sources at the chamber injector and a constant Mach number nozzle. An eigenfunction-matching method is used to solve the linearized partial differential equations describing the unsteady flow field for both models. Boundary layer corrections to this unsteady flow are in a mechanical energy dissipation model to evaluate viscous and turbulence effects within the flow. An integral instability relationship is then employed to predict the decay rate of the oscillations. Results of this analysis agree qualitatively with experimental observations and 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, oscillation amplitude, baffle configuration, and oscillation mode is examined.

  8. Hybrid rigid/soft and biologic/synthetic materials: polymers grafted onto cellulose microcrystals.

    PubMed

    Harrisson, Simon; Drisko, Glenna L; Malmström, Eva; Hult, Anders; Wooley, Karen L

    2011-04-11

    Rigid nanoscale polymer rods were prepared by grafting preformed amine-terminated poly(styrene) and poly(tert-butyl acrylate) onto oxidized cellulose microcrystals. Low polydispersity polymers, grown using atom transfer radical polymerization, were characterized and purified prior to cellulose attachment. Oxidation of the cellulose microcrystal led to the formation of carboxylic acids on the surface of the microcrystals. Covalent attachment of the polymers onto the cellulose microcrystals was achieved via a carbodiimide-mediated amidation reaction. The length and diameter of the polymer-cellulose composites increased upon surface modification. Typically, polymer-cellulose composites are synthesized by a grafting-from method because it can be difficult to obtain sufficient graft density using a grafting-to preparation. However, the composites reported here comprised 60-64% grafted polymer by mass. This degree of grafting-to allowed the composite to form stable suspensions in organic solvents.

  9. 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.

  10. 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.

  11. 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.

  12. Sound scattering by rigid oblate spheroids, with implication to pressure gradient microphones

    NASA Technical Reports Server (NTRS)

    Maciulaitis, A.; Seiner, J.; Norum, T. D.

    1976-01-01

    The frequency limit below which sound scattering by a microphone body is sufficiently small to permit accurate pressure gradient measurements was determined. The sound pressure was measured at various points on the surface of a rigid oblate spheroid illuminated by spherical waves generated by a point source at a large distance from the spheroid, insuring an essentially plane sound field. The measurements were made with small pressure microphones flush mounted from the inside of the spheroid model. Numerical solutions were obtained for a variety of spheroid shapes, including that of the experimental model. Very good agreement was achieved between the experimental and theoretical results. It was found that scattering effects are insignificant if the ratio of the major circumference of the spheroid to the wavelength of the incident sound is less than about 0.7, this number being dependent upon the shape of the spheroid. This finding can be utilized in the design of pressure gradient microphones.

  13. 21 CFR 886.5918 - Rigid gas permeable contact lens care products.

    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 care products... contact lens care products. (a) Identification. A rigid gas permeable contact lens care product is a... rigid gas permeable contact lens. This includes all solutions and tablets used together with rigid...

  14. 21 CFR 886.5918 - Rigid gas permeable contact lens care products.

    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 care products... contact lens care products. (a) Identification. A rigid gas permeable contact lens care product is a... rigid gas permeable contact lens. This includes all solutions and tablets used together with rigid...

  15. 21 CFR 886.5918 - Rigid gas permeable contact lens care products.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Rigid gas permeable contact lens care products... contact lens care products. (a) Identification. A rigid gas permeable contact lens care product is a... rigid gas permeable contact lens. This includes all solutions and tablets used together with rigid...

  16. 21 CFR 886.5918 - Rigid gas permeable contact lens care products.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Rigid gas permeable contact lens care products... contact lens care products. (a) Identification. A rigid gas permeable contact lens care product is a... rigid gas permeable contact lens. This includes all solutions and tablets used together with rigid...

  17. 21 CFR 886.5918 - Rigid gas permeable contact lens care products.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Rigid gas permeable contact lens care products... contact lens care products. (a) Identification. A rigid gas permeable contact lens care product is a... rigid gas permeable contact lens. This includes all solutions and tablets used together with rigid...

  18. Jamming graphs: A local approach to global mechanical rigidity

    NASA Astrophysics Data System (ADS)

    Lopez, Jorge H.; Cao, L.; Schwarz, J. M.

    2013-12-01

    We revisit the concept of minimal rigidity as applied to frictionless, repulsive soft sphere packings in two dimensions with the introduction of the jamming graph. Minimal rigidity is a purely combinatorial property encoded via Laman's theorem in two dimensions. It constrains the global, average coordination number of the graph, for example. However, minimal rigidity does not address the geometry of local mechanical stability. The jamming graph contains both properties of global mechanical stability at the onset of jamming and local mechanical stability. We demonstrate how jamming graphs can be constructed using local moves via the Henneberg construction such that these graphs fall under the jurisdiction of correlated percolation. We then probe how jamming graphs destabilize, or become unjammed, by deleting a bond and computing the resulting rigid cluster distribution. We also study how the system restabilizes with the addition of new contacts and how a jamming graph with extra (redundant) contacts destabilizes. The latter endeavor allows us to probe a disk packing in the rigid phase and uncover a potentially new diverging length scale associated with the random deletion of contacts as compared to the study of cut-out (or frozen-in) subsystems.

  19. Unified Creep Plasticity Damage (UCPD) Model for Rigid Polyurethane Foams.

    SciTech Connect

    Neilsen, Michael K.; Lu, Wei-Yang; Scherzinger, William M.; Hinnerichs, Terry D.; Lo, Chi S.

    2015-06-01

    Numerous experiments were performed to characterize the mechanical response of several different rigid polyurethane foams (FR3712, PMDI10, PMDI20, and TufFoam35) to large deformation. In these experiments, the effects of load path, loading rate, and temperature were investigated. Results from these experiments indicated that rigid polyurethane foams exhibit significant volumetric and deviatoric plasticity when they are compressed. Rigid polyurethane foams were also found to be very strain-rate and temperature dependent. These foams are also rather brittle and crack when loaded to small strains in tension or to larger strains in compression. Thus, a new Unified Creep Plasticity Damage (UCPD) model was developed and implemented into SIERRA with the name Foam Damage to describe the mechanical response of these foams to large deformation at a variety of temperatures and strain rates. This report includes a description of recent experiments and experimental findings. Next, development of a UCPD model for rigid, polyurethane foams is described. Selection of material parameters for a variety of rigid polyurethane foams is then discussed and finite element simulations with the new UCPD model are compared with experimental results to show behavior that can be captured with this model.

  20. Enhancement of parkinsonian rigidity with contralateral hand activation

    PubMed Central

    Powell, Douglas; Hanson, Nicholas; Threlkeld, A. Joseph; Fang, Xiang; Xia, Ruiping

    2011-01-01

    Objective Quantify the enhancement of parkinsonian rigidity associated with a contralateral activation maneuver. Methods Twelve subjects with PD and eight controls participated in the study protocol. Subjects’ tested hand was displaced by a servo-motor throughout wrist flexion and extension motions of 60° without and with a concurrent gripping activation in the contralateral hand, referred to as passive and active conditions, respectively. Subjects with PD were tested in both OFF-Med and ON-Med states. Rigidity was quantified by integrating torque with position during both flexion and extension (torque resistance). ANOVA was performed to assess the effect of contralateral activation on rigidity. Results PD patients had significantly (0.038) enhanced torque resistance in OFF-Med compared to healthy controls and ON-MED. In the Active condition, differences in torque resistance were magnified (p=0.002). Medication substantially reduced differences in torque resistance between controls and PD patients in the passive and active conditions. Conclusions A contralateral activation maneuver substantially increases rigidity in patients with PD, specifically the OFF-MED state. Rigidity is reduced with the application of dopaminergic medication, even with the presence of a contralateral activation maneuver. Significance These data support the use of a contralateral activation maneuver as a tool in the diagnosis of PD. PMID:21330199

  1. Packing density of rigid aggregates is independent of scale

    PubMed Central

    Zangmeister, Christopher D.; Radney, James G.; Dockery, Lance T.; Young, Jessica T.; Ma, Xiaofei; You, Rian; Zachariah, Michael R.

    2014-01-01

    Large planetary seedlings, comets, microscale pharmaceuticals, and nanoscale soot particles are made from rigid, aggregated subunits that are compacted under low compression into larger structures spanning over 10 orders of magnitude in dimensional space. Here, we demonstrate that the packing density (θf) of compacted rigid aggregates is independent of spatial scale for systems under weak compaction. The θf of rigid aggregated structures across six orders of magnitude were measured using nanoscale spherical soot aerosol composed of aggregates with ∼17-nm monomeric subunits and aggregates made from uniform monomeric 6-mm spherical subunits at the macroscale. We find θf = 0.36 ± 0.02 at both dimensions. These values are remarkably similar to θf observed for comet nuclei and measured values of other rigid aggregated systems across a wide variety of spatial and formative conditions. We present a packing model that incorporates the aggregate morphology and show that θf is independent of both monomer and aggregate size. These observations suggest that the θf of rigid aggregates subject to weak compaction forces is independent of spatial dimension across varied formative conditions. PMID:24927577

  2. Barriers to cooperation aid ideological rigidity and threaten societal collapse.

    PubMed

    Jusup, Marko; Matsuo, Tadasu; Iwasa, Yoh

    2014-05-01

    Understanding the factors that promote, disrupt, or shape the nature of cooperation is one of the main tasks of evolutionary biology. Here, we focus on attitudes and beliefs supportive of in-group favoritism and strict adherence to moral consensus, collectively known as ideological rigidity, that have been linked with both ends of the political spectrum. The presence among the political right and the left is likely to make ideological rigidity a major determinant of the political discourse with an important social function. To better understand this function, we equip the indirect reciprocity framework--widely used to explain evaluation-mediated social cooperation--with multiple stylized value systems, each corresponding to the different degree of ideological rigidity. By running game theoretical simulations, we observe the competitive evolution of these systems, map conditions that lead to more ideologically rigid societies, and identify potentially disastrous outcomes. In particular, we uncover that barriers to cooperation aid ideological rigidity. The society may even polarize to the extent where social parasites overrun the population and cause the complete collapse of the social structure. These results have implications for lawmakers globally, warning against restrictive or protectionist policies.

  3. A critique of vorticity analysis using rigid clasts

    NASA Astrophysics Data System (ADS)

    Li, Changcheng; Jiang, Dazhi

    2011-03-01

    Estimating the kinematic vorticity numbers from rock fabrics presents many problems. In this paper we use numerical modeling to investigate the reliability of those widely-used vorticity analysis methods using rigid clasts. We use very simple flows (steady state, homogeneous, and having monoclinic symmetry) to represent plane-straining zones and transpressional zones and assume that the rotation of rigid clasts perfectly obeys the theory of Jeffery (1922, Proceedings of the Royal Society of London A102, 161-179). These are assumptions made in current vorticity analysis using rigid clasts. Even with these simple assumptions, our modeling shows that the current methods have intrinsic uncertainties so large that it is pointless to use the estimated vorticity numbers to constrain shear zone boundary conditions and kinematics. It is perfectly consistent with numerical modeling results if the currently reported vorticity numbers estimated from rigid clasts (in the range of 0.50-0.85) are all interpreted as being from natural shear zones with close-to-simple-shearing flows. The large uncertainties arise because the motion of rigid clasts is intrinsically a three dimensional problem.

  4. Maintain rigid structures in Verlet based cartesian molecular dynamics simulations.

    PubMed

    Tao, Peng; Wu, Xiongwu; Brooks, Bernard R

    2012-10-07

    An algorithm is presented to maintain rigid structures in Verlet based cartesian molecular dynamics (MD) simulations. After each unconstrained MD step, the coordinates of selected particles are corrected to maintain rigid structures through an iterative procedure of rotation matrix computation. This algorithm, named as SHAPE and implemented in CHARMM program suite, avoids the calculations of Lagrange multipliers, so that the complexity of computation does not increase with the number of particles in a rigid structure. The implementation of this algorithm does not require significant modification of propagation integrator, and can be plugged into any cartesian based MD integration scheme. A unique feature of the SHAPE method is that it is interchangeable with SHAKE for any object that can be constrained as a rigid structure using multiple SHAKE constraints. Unlike SHAKE, the SHAPE method can be applied to large linear (with three or more centers) and planar (with four or more centers) rigid bodies. Numerical tests with four model systems including two proteins demonstrate that the accuracy and reliability of the SHAPE method are comparable to the SHAKE method, but with much more applicability and efficiency.

  5. 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.

  6. Barriers to Cooperation Aid Ideological Rigidity and Threaten Societal Collapse

    PubMed Central

    Jusup, Marko; Matsuo, Tadasu; Iwasa, Yoh

    2014-01-01

    Understanding the factors that promote, disrupt, or shape the nature of cooperation is one of the main tasks of evolutionary biology. Here, we focus on attitudes and beliefs supportive of in-group favoritism and strict adherence to moral consensus, collectively known as ideological rigidity, that have been linked with both ends of the political spectrum. The presence among the political right and the left is likely to make ideological rigidity a major determinant of the political discourse with an important social function. To better understand this function, we equip the indirect reciprocity framework – widely used to explain evaluation-mediated social cooperation – with multiple stylized value systems, each corresponding to the different degree of ideological rigidity. By running game theoretical simulations, we observe the competitive evolution of these systems, map conditions that lead to more ideologically rigid societies, and identify potentially disastrous outcomes. In particular, we uncover that barriers to cooperation aid ideological rigidity. The society may even polarize to the extent where social parasites overrun the population and cause the complete collapse of the social structure. These results have implications for lawmakers globally, warning against restrictive or protectionist policies. PMID:24809975

  7. Interaction between a flexible filament and a downstream rigid body

    NASA Astrophysics Data System (ADS)

    Tian, Fang-Bao; Luo, Haoxiang; Zhu, Luoding; Lu, Xi-Yun

    2010-08-01

    A filament flapping in the bow wake of a rigid body is considered in order to study the hydrodynamic interaction between flexible and rigid bodies in tandem arrangement. Both numerical and experimental methods are adopted to analyze the motion of the filament, and the drag force on both bodies is computed. It is shown that the results largely depend on the gap between the two objects and the Reynolds number. The flexible body may have larger vibration amplitude but meanwhile experience a reduced drag force. On the other hand, the trailing rigid body enjoys a drag reduction. The qualitative behavior of the filament is independent of the filament’s length and mass ratio or the shape of the rigid body for the parameter regime considered. The result is in contrast with the interaction between two rigid or two flexible objects in tandem arrangement, and it may provide a physical insight into the understanding of the aquatic animals swimming in the bow wake of ships or staying in the bow wake of stationary structures.

  8. Interaction between a flexible filament and a downstream rigid body.

    PubMed

    Tian, Fang-Bao; Luo, Haoxiang; Zhu, Luoding; Lu, Xi-Yun

    2010-08-01

    A filament flapping in the bow wake of a rigid body is considered in order to study the hydrodynamic interaction between flexible and rigid bodies in tandem arrangement. Both numerical and experimental methods are adopted to analyze the motion of the filament, and the drag force on both bodies is computed. It is shown that the results largely depend on the gap between the two objects and the Reynolds number. The flexible body may have larger vibration amplitude but meanwhile experience a reduced drag force. On the other hand, the trailing rigid body enjoys a drag reduction. The qualitative behavior of the filament is independent of the filament's length and mass ratio or the shape of the rigid body for the parameter regime considered. The result is in contrast with the interaction between two rigid or two flexible objects in tandem arrangement, and it may provide a physical insight into the understanding of the aquatic animals swimming in the bow wake of ships or staying in the bow wake of stationary structures.

  9. AOP: An R Package For Sufficient Causal Analysis in Pathway ...

    EPA Pesticide Factsheets

    Summary: How can I quickly find the key events in a pathway that I need to monitor to predict that a/an beneficial/adverse event/outcome will occur? This is a key question when using signaling pathways for drug/chemical screening in pharma-cology, toxicology and risk assessment. By identifying these sufficient causal key events, we have fewer events to monitor for a pathway, thereby decreasing assay costs and time, while maximizing the value of the information. I have developed the “aop” package which uses backdoor analysis of causal net-works to identify these minimal sets of key events that are suf-ficient for making causal predictions. Availability and Implementation: The source and binary are available online through the Bioconductor project (http://www.bioconductor.org/) as an R package titled “aop”. The R/Bioconductor package runs within the R statistical envi-ronment. The package has functions that can take pathways (as directed graphs) formatted as a Cytoscape JSON file as input, or pathways can be represented as directed graphs us-ing the R/Bioconductor “graph” package. The “aop” package has functions that can perform backdoor analysis to identify the minimal set of key events for making causal predictions.Contact: burgoon.lyle@epa.gov This paper describes an R/Bioconductor package that was developed to facilitate the identification of key events within an AOP that are the minimal set of sufficient key events that need to be tested/monit

  10. AOP: An R Package For Sufficient Causal Analysis in Pathway ...

    EPA Pesticide Factsheets

    Summary: How can I quickly find the key events in a pathway that I need to monitor to predict that a/an beneficial/adverse event/outcome will occur? This is a key question when using signaling pathways for drug/chemical screening in pharma-cology, toxicology and risk assessment. By identifying these sufficient causal key events, we have fewer events to monitor for a pathway, thereby decreasing assay costs and time, while maximizing the value of the information. I have developed the “aop” package which uses backdoor analysis of causal net-works to identify these minimal sets of key events that are suf-ficient for making causal predictions. Availability and Implementation: The source and binary are available online through the Bioconductor project (http://www.bioconductor.org/) as an R package titled “aop”. The R/Bioconductor package runs within the R statistical envi-ronment. The package has functions that can take pathways (as directed graphs) formatted as a Cytoscape JSON file as input, or pathways can be represented as directed graphs us-ing the R/Bioconductor “graph” package. The “aop” package has functions that can perform backdoor analysis to identify the minimal set of key events for making causal predictions.Contact: burgoon.lyle@epa.gov This paper describes an R/Bioconductor package that was developed to facilitate the identification of key events within an AOP that are the minimal set of sufficient key events that need to be tested/monit

  11. 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.

  12. Detecting necessary and sufficient parts for assembling a functional weapon

    NASA Astrophysics Data System (ADS)

    Hempelmann, Christian F.; Solomon, Divya; Arslan, Abdullah N.; Attardo, Salvatore; Blount, Grady P.; Adkins, Tracy; Sirakov, Nikolay M.

    2017-05-01

    Continuing our previous research to visually extract and visually and conceptually match weapons, this study develops a method to determine whether a set of weapon parts visually extracted from images taken from different scenes can be assembled as a firing weapon. This new approach identifies potential weapons in the ontology via tracing detected necessary and sufficient parts through their meronymic relation to the whole weapon. A fast algorithm for identifying potential weapons that can be assembled from a given set of detected parts is presented.

  13. Sufficient conditions for a memory-kernel master equation

    NASA Astrophysics Data System (ADS)

    Chruściński, Dariusz; Kossakowski, Andrzej

    2016-08-01

    We derive sufficient conditions for the memory-kernel governing nonlocal master equation which guarantee a legitimate (completely positive and trace-preserving) dynamical map. It turns out that these conditions provide natural parametrizations of the dynamical map being a generalization of the Markovian semigroup. This parametrization is defined by the so-called legitimate pair—monotonic quantum operation and completely positive map—and it is shown that such a class of maps covers almost all known examples from the Markovian semigroup, the semi-Markov evolution, up to collision models and their generalization.

  14. Technology for human self-sufficiency in space

    NASA Technical Reports Server (NTRS)

    Anderson, John L.

    1988-01-01

    A proposed Pathfinder program would determine the critical human and technology requirements for human self-sufficiency and productivity on manned and long-duration missions to the moon and Mars. Human health would require countermeasures against weightlessness, protection from space radiation and habitats conducive to psychological well-being. Life support systems would need regeneration of expendable resources, power systems for plant life support and processing; and microbial contaminant control. Operational performance requirements include extravehicular activities suit, interactive systems for shared control between humans and computers, and human-centered semi-autonomous systems.

  15. Geometric derivations of minimal sets of sufficient multiview constraints

    USGS Publications Warehouse

    Thomas, Orrin H.; Oshel, Edward R.

    2012-01-01

    Geometric interpretations of four of the most common determinant formulations of multiview constraints are given, showing that they all enforce the same geometry and that all of the forms commonly in use in the machine vision community are a subset of a more general form. Generalising the work of Yi Ma yields a new general 2 x 2 determinant trilinear and 3 x 3 determinant quadlinear. Geometric descriptions of degenerate multiview constraints are given, showing that it is necessary, but insufficient, that the determinant equals zero. Understanding the degeneracies leads naturally into proofs for minimum sufficient sets of bilinear, trilinear and quadlinear constraints for arbitrary numbers of conjugate observations.

  16. Insulin secretion abnormalities in exocrine pancreatic sufficient cystic fibrosis patients.

    PubMed

    Wooldridge, Jamie L; Szczesniak, Rhonda D; Fenchel, Matthew C; Elder, Deborah A

    2015-11-01

    The aim of this study is to assess insulin secretion in pediatric cystic fibrosis (CF) patients with exocrine pancreatic sufficiency. Glucose and insulin responses during an oral glucose tolerance test (OGTT) were measured in 146 CF patients. Patients were divided into exocrine sufficient (CF-PS) and insufficient (CF-PI) groups based on pancreatic enzyme usage and fecal elastase. A reference group included healthy, non-diabetic subjects. All CF groups showed reduced insulin secretion as measured by insulinogenic index. The CF-PS patients had normal glucose tolerance. There was a direct correlation between BMI z-score and insulin area under the curve. Patients with CF have reduced insulin secretion during an OGTT regardless of exocrine pancreatic status. The abnormal insulin secretion in all CF patients may predispose them for glucose intolerance, particularly when challenged by inflammation, infection, or nutritional deficiency. In addition, the diminished insulin secretion may contribute to increased catabolism. Lastly, the CF-related diabetes (CFRD) screening guidelines should be followed by all CF patients regardless of pancreatic status. Copyright © 2015 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

  17. Insulin Secretion Abnormalities in Exocrine Pancreatic Sufficient Cystic Fibrosis Patients

    PubMed Central

    Wooldridge, Jamie L.; Szczesniak, Rhonda D.; Fenchel, Matthew C.; Elder, Deborah A.

    2015-01-01

    BACKGROUND To assess insulin secretion in pediatric cystic fibrosis (CF) patients with exocrine pancreatic sufficiency. METHODS Glucose and insulin responses during an oral glucose tolerance test (OGTT) were measured in 146 CF patients. Patients were divided into exocrine sufficient (CF-PS) and insufficient (CF-PI) groups based on pancreatic enzyme usage and fecal elastase. A reference group included healthy, non-diabetic subjects. RESULTS All CF groups showed reduced insulin secretion as measured by insulinogenic index. The CF-PS patients had normal glucose tolerance. There was direct correlation between BMI z-score and insulin area under the curve. CONCLUSION Patients with CF have reduced insulin secretion during an OGTT regardless of exocrine pancreatic status. The abnormal insulin secretion in all CF patients may predispose them for glucose intolerance, particularly when challenged by inflammation, infection, or nutritional deficiency. In addition, the diminished insulin secretion may contribute to increased catabolism. Lastly, the CF-related diabetes (CFRD) screening guidelines should be followed by all CF patients regardless of pancreatic status. PMID:25754095

  18. Sequences sufficient for programming imprinted germline DNA methylation defined.

    PubMed

    Park, Yoon Jung; Herman, Herry; Gao, Ying; Lindroth, Anders M; Hu, Benjamin Y; Murphy, Patrick J; Putnam, James R; Soloway, Paul D

    2012-01-01

    Epigenetic marks are fundamental to normal development, but little is known about signals that dictate their placement. Insights have been provided by studies of imprinted loci in mammals, where monoallelic expression is epigenetically controlled. Imprinted expression is regulated by DNA methylation programmed during gametogenesis in a sex-specific manner and maintained after fertilization. At Rasgrf1 in mouse, paternal-specific DNA methylation on a differential methylation domain (DMD) requires downstream tandem repeats. The DMD and repeats constitute a binary switch regulating paternal-specific expression. Here, we define sequences sufficient for imprinted methylation using two transgenic mouse lines: One carries the entire Rasgrf1 cluster (RC); the second carries only the DMD and repeats (DR) from Rasgrf1. The RC transgene recapitulated all aspects of imprinting seen at the endogenous locus. DR underwent proper DNA methylation establishment in sperm and erasure in oocytes, indicating the DMD and repeats are sufficient to program imprinted DNA methylation in germlines. Both transgenes produce a DMD-spanning pit-RNA, previously shown to be necessary for imprinted DNA methylation at the endogenous locus. We show that when pit-RNA expression is controlled by the repeats, it regulates DNA methylation in cis only and not in trans. Interestingly, pedigree history dictated whether established DR methylation patterns were maintained after fertilization. When DR was paternally transmitted followed by maternal transmission, the unmethylated state that was properly established in the female germlines could not be maintained. This provides a model for transgenerational epigenetic inheritance in mice.

  19. Efficient computation of root mean square deviations under rigid transformations.

    PubMed

    Hildebrandt, Anna K; Dietzen, Matthias; Lengauer, Thomas; Lenhof, Hans-Peter; Althaus, Ernst; Hildebrandt, Andreas

    2014-04-15

    The computation of root mean square deviations (RMSD) is an important step in many bioinformatics applications. If approached naively, each RMSD computation takes time linear in the number of atoms. In addition, a careful implementation is required to achieve numerical stability, which further increases runtimes. In practice, the structural variations under consideration are often induced by rigid transformations of the protein, or are at least dominated by a rigid component. In this work, we show how RMSD values resulting from rigid transformations can be computed in constant time from the protein's covariance matrix, which can be precomputed in linear time. As a typical application scenario is protein clustering, we will also show how the Ward-distance which is popular in this field can be reduced to RMSD evaluations, yielding a constant time approach for their computation. Copyright © 2014 Wiley Periodicals, Inc.

  20. 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.

  1. Method to estimate center of rigidity using vibration recordings

    USGS Publications Warehouse

    Safak, Erdal; Celebi, 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.

  2. 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.

  3. Development of probabilistic rigid pavement design methodologies for military airfields

    NASA Astrophysics Data System (ADS)

    Witczak, M. W.; Uzan, J.; Johnson, M.

    1983-12-01

    The current Corps of Engineers design procedures for rigid airfield pavements is based on the Westergaard free edge stress slab theory, and a proposed procedure is based on the multilayer elastic theory. These two design procedures have been expanded to airfield pavement designs expressed in probabilistic and reliability terms. Further developments were required in these procedures to make the analysis more practicable. Two major investigations were conducted: (1) Evaluation and use of the composite modulus of elasticity for layers beneath the rigid pavement, and (2) Evaluation of the maximum tensile stress at the bottom of the slab for different aircraft types. Derivations obtained from the investigation of the composite modulus and maximum tensile stress are reported and are included in computer programs for probabilistic/reliability analysis of rigid pavements. The approximate closed form (Taylor series expansion) is utilized. Example runs of the computer program are presented.

  4. 1/f noise and very high spectral rigidity

    NASA Astrophysics Data System (ADS)

    Relaño, A.; Retamosa, J.; Faleiro, E.; Molina, R. A.; Zuker, A. P.

    2006-02-01

    It was recently pointed out that the spectral fluctuations of quantum systems are formally analogous to discrete time series, and therefore their structure can be characterized by the power spectrum of the signal. Moreover, it is found that the power spectrum of chaotic spectra displays a 1/f behavior, while that of regular systems follows a 1/f2 law. This analogy provides a link between the concepts of spectral rigidity and antipersistence. Trying to get a deeper understanding of this relationship, we have studied the correlation structure of spectra with high spectral rigidity. Using an appropriate family of random Hamiltonians, we increase the spectral rigidity up to hindering completely the spectral fluctuations. Analyzing the long range correlation structure a neat power law 1/f has been found for all the spectra, along the whole process. Therefore, 1/f noise is the characteristic fingerprint of a transition that, preserving the scale-free correlation structure, hinders completely the fluctuations of the spectrum.

  5. Fibroblast motility on substrates with different rigidities: modeling approach

    NASA Astrophysics Data System (ADS)

    Gracheva, Maria; Dokukina, Irina

    2009-03-01

    We develop a discrete model for cell locomotion on substrates with different rigidities and simulate experiments described in Lo, Wang, Dembo, Wang (2000) ``Cell movement is guided by the rigidity of the substrate'', Biophys. J. 79: 144-152. In these experiments fibroblasts were planted on a substrate with a step rigidity and showed preference for locomotion over stiffer side of the substrate when approaches the boundary between the soft and the stiff sides of the substrate. The model reproduces experimentally observed behavior of fibroblasts. In particular, we are able to show with our model how cell characteristics (such as cell length, shape, area and speed) change during cell crawling through the ``soft-stiff'' substrate boundary. Also, our model suggests the temporary increase of both cell speed and area in that very moment when cell leaves soft side of substrate.

  6. Toxicity evaluation and hazard review for Rigid Foam

    SciTech Connect

    Archuleta, M.M.; Stocum, W.E.

    1994-02-01

    Rigid Foam is a chemical delay foam used to completely encapsulate an object or to block access to an area. Prior studies have indicated that the final foam product is essentially non-toxic. The purpose of this study was to evaluate and summarize the current chemical and toxicological data available on the components of Rigid Foam and to update the information available on the toxicity of the final Rigid Foam product. Since the possibility exists for a partial deployment of Rigid Foam where only one of the components is released, this study also examined the toxicity of its chemical constituents. Rigid Foam is composed of an {open_quotes}A{close_quotes} and {open_quotes}B{close_quotes} Component. The {open_quotes}A{close_quotes} component is primarily a polymeric isocyanate and the {open_quotes}B{close_quotes} component is a mixture of polyols. In addition to the primary constituents, dichlorodifluoromethane and trichlorofluoromethane are present as blowing agents along with catalysts and silicone surfactants necessary for foaming. The pre-deployed {open_quotes}A{close_quotes} and {open_quotes}B{close_quotes} components are stored in separate vessels and are brought together in static mixing nozzles for dispersal. The results of this evaluation indicate that a completely deployed Rigid Foam under normal conditions is essentially non-toxic as determined previously. However, in the event of a partial deployment or deployment of an individual component directly at an unprotected individual, the degree of hazard is increased due to the toxic and corrosive nature of the individual constituents. The health hazard would depend on the properties of the material to which the person was exposed.

  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. 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.

  9. Superior cell penetration by a rigid and anisotropic synthetic protein.

    PubMed

    Nakayama, Norihisa; Hagiwara, Kyoji; Ito, Yoshihiro; Ijiro, Kuniharu; Osada, Yoshihito; Sano, Ken-Ichi

    2015-03-10

    Molecules with structural anisotropy and rigidity, such as asbestos, demonstrate high cell-penetrating activity but also high toxicity. Here we synthesize a biodegradable, rigid, and fibrous artificial protein, CCPC 140, as a potential vehicle for cellular delivery. CCPC 140 penetrated 100% of cells tested in vitro, even at a concentration of 3.1 nM-superior to previously reported cell-penetrating peptides. The effects of cell-strain-dependency and aspect ratio on the cell-penetrating activity of CCPC 140 were also investigated.

  10. 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.

  11. Shear-induced rigidity in spider silk glands

    NASA Astrophysics Data System (ADS)

    Koski, Kristie J.; McKiernan, Keri; Akhenblit, Paul; Yarger, Jeffery L.

    2012-09-01

    We measure the elastic stiffnesses of the concentrated viscous protein solution of the dehydrated Nephila clavipes major ampullate gland with Brillouin light scattering. The glandular material shows no rigidity but possesses a tensile stiffness similar to that of spider silk. We show, however, that with application of a simple static shear, the mechanical properties of the spider gland protein mixture can be altered irreversibly, lowering symmetry and enabling shear waves to be supported, thus, giving rise to rigidity and yielding elastic properties similar to those of the naturally spun (i.e., dynamically sheared) silk.

  12. The Rigid-Flexible System Dynamics Model of Highline Cable

    NASA Astrophysics Data System (ADS)

    Xing, Daoqi; Li, Nan; Zhang, Shiyun

    The paper researches rigid flexible system dynamics model of the rope, and used it to simulate sealift Highline based on the multi-body dynamics theory. Meanwhile the paper simulated to the sea dry cargo replenishment of transverse process, then gain the conclusion that the rigid flexible dynamic model get in the paper is more close to the Caucasus, and the dynamic calculation results closer to the actual situation, through the analysis of simulation results, and combined with the actual situation in the Caucasus the structure of overhead cable.

  13. Buffers affect the bending rigidity of model lipid membranes.

    PubMed

    Bouvrais, Hélène; Duelund, Lars; Ipsen, John H

    2014-01-14

    In biophysical and biochemical studies of lipid bilayers the influence of the used buffer is often ignored or assumed to be negligible on membrane structure, elasticity, or physical properties. However, we here present experimental evidence, through bending rigidity measurements performed on giant vesicles, of a more complex behavior, where the buffering molecules may considerably affect the bending rigidity of phosphatidylcholine bilayers. Furthermore, a synergistic effect on the bending modulus is observed in the presence of both salt and buffer molecules, which serves as a warning to experimentalists in the data interpretation of their studies, since typical lipid bilayer studies contain buffer and ion molecules.

  14. Lyapunov instability of rigid diatomic molecules in three dimensions.

    PubMed

    Shin, Y H; Ihm, D C; Lee, E K

    2001-10-01

    We study the Lyapunov instability of a three-dimensional fluid composed of rigid diatomic molecules by molecular dynamics simulation. We use center-of-mass coordinates and angular variables for the configurational space variables. The spectra of Lyapunov exponents are obtained for 32 rigid diatomic molecules interacting through the Weeks-Chandler-Andersen potential for various bond lengths and densities. We show the general trends and characteristic features of the spectra of the Lyapunov exponents, and discuss the different contributions between translational and rotational degrees of freedom depending on the density and the bond length from the calculation of the projection of a certain subspace of the tangent space vectors.

  15. Tracking Non-rigid Structures in Computer Simulations

    SciTech Connect

    Gezahegne, A; Kamath, C

    2008-01-10

    A key challenge in tracking moving objects is the correspondence problem, that is, the correct propagation of object labels from one time step to another. This is especially true when the objects are non-rigid structures, changing shape, and merging and splitting over time. In this work, we describe a general approach to tracking thousands of non-rigid structures in an image sequence. We show how we can minimize memory requirements and generate accurate results while working with only two frames of the sequence at a time. We demonstrate our results using data from computer simulations of a fluimix problem.

  16. Lyapunov instability of rigid diatomic molecules in three dimensions

    NASA Astrophysics Data System (ADS)

    Shin, Young-Han; Ihm, Dong-Chul; Lee, Eok-Kyun

    2001-10-01

    We study the Lyapunov instability of a three-dimensional fluid composed of rigid diatomic molecules by molecular dynamics simulation. We use center-of-mass coordinates and angular variables for the configurational space variables. The spectra of Lyapunov exponents are obtained for 32 rigid diatomic molecules interacting through the Weeks-Chandler-Andersen potential for various bond lengths and densities. We show the general trends and characteristic features of the spectra of the Lyapunov exponents, and discuss the different contributions between translational and rotational degrees of freedom depending on the density and the bond length from the calculation of the projection of a certain subspace of the tangent space vectors.

  17. Enhanced motility of a microswimmer in rigid and elastic confinement.

    PubMed

    Ledesma-Aguilar, Rodrigo; Yeomans, Julia M

    2013-09-27

    We analyze the effect of confining rigid and elastic boundaries on the motility of a model dipolar microswimmer. Flexible boundaries are deformed by the velocity field of the swimmer in such a way that the motility of both extensile and contractile swimmers is enhanced. The magnitude of the increase in swimming velocity is controlled by the ratio of the swimmer-advection and elastic time scales, and the dipole moment of the swimmer. We explain our results by considering swimming between inclined rigid boundaries.

  18. Enhanced Motility of a Microswimmer in Rigid and Elastic Confinement

    NASA Astrophysics Data System (ADS)

    Ledesma-Aguilar, Rodrigo; Yeomans, Julia M.

    2013-09-01

    We analyze the effect of confining rigid and elastic boundaries on the motility of a model dipolar microswimmer. Flexible boundaries are deformed by the velocity field of the swimmer in such a way that the motility of both extensile and contractile swimmers is enhanced. The magnitude of the increase in swimming velocity is controlled by the ratio of the swimmer-advection and elastic time scales, and the dipole moment of the swimmer. We explain our results by considering swimming between inclined rigid boundaries.

  19. Drag reduction characteristics of small amplitude rigid surface waves

    NASA Technical Reports Server (NTRS)

    Cary, A. M., Jr.; Weinstein, L. M.; Bushnell, D. M.

    1980-01-01

    The possibility of reducing drag by using rigid, wavy surfaces is investigated both analytically and experimentally. Although pressure drag for rigid sine-wave surfaces can be predicted empirically, viscous drag for even shallow waves was poorly predicted by state-of-the-art turbulent boundary layer calculation procedures. Calculations for the effects of geometric and fluid variables on total wave drag are presented under the philosophy that trends will be nearly correct even though levels are probably incorrect. Experiments by the present authors indicate that a total drag reduction with wavy walls is possible.

  20. Shape optimization of rigid inclusions for elastic plates with cracks

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Viktor

    2016-06-01

    In the paper, we consider an optimal control problem of finding the most safe rigid inclusion shapes in elastic plates with cracks from the viewpoint of the Griffith rupture criterion. We make use of a general Kirchhoff-Love plate model with both vertical and horizontal displacements, and nonpenetration conditions are fulfilled on the crack faces. The dependence of the first derivative of the energy functional with respect to the crack length on regular shape perturbations of the rigid inclusion is analyzed. It is shown that there exists a solution of the optimal control problem.

  1. Fifty years of progress in geomagnetic cutoff rigidity determinations

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

    This paper is a review of the progress made in geomagnetic cutoff rigidity calculations over the past 50 years. Determinations of cosmic ray trajectories, and hence cutoff rigidities, using digital computers began in 1956 and progressed slowly until 1962 when McCracken developed an efficient computer program to determine cosmic ray trajectories in a high degree simulation of the geomagnetic field. The application of this cosmic ray trajectory technique was limited by the available computer power. As computers became faster it was possible to determine vertical cutoff rigidity values for cosmic ray stations and coarse world grids; however, the computational effort required was formidable for the computers of the 1960s. Since most cosmic ray experiments were conducted on the surface of the Earth, the vertical cutoff rigidity was adopted as a standard reference value. The effective cutoff value derived from trajectory calculations appeared to be adequate for ordering cosmic ray data from latitude surveys. As the geomagnetic field evolution became more apparent, it was found necessary to update the world grid of cutoff rigidity values using more accurate descriptions of the geomagnetic field. In the 1970s and 1980s it became possible to do experimental verification of the accuracy of these cosmic ray cutoff determinations and also to design experiments based on these cutoff rigidity calculations. The extensive trajectory calculations done in conjunction with the HEAO-3 satellite and a comparison between these experimental measurements and the trajectory calculations verified the Störmer theory prediction regarding angular cutoff variations and also confirmed that the structure of the first order penumbra is very stable and could be used for isotope separation. Contemporary work in improving cutoff rigidities seems to be concentrating on utilizing improved magnetospheric models in an effort to determine more accurate geomagnetic cutoff values. When using geomagnetic

  2. A Three-Dimensional Nonsingular Simulation of Rigid Manipulators

    DTIC Science & Technology

    1988-09-01

    Verbos September 1988 Thesis Advisor: D. Smith Approved for public release; distribution is unlimited. JT IC T".LEcTE 0 89 1 04",026 Unclassified...Simulation of Rigid Manipulators 12 Personal Author(s) Robert M. Verbos 13a Type of Report 13b Time Covered 14 Date of Report (year, month,day) 15 Page Count...Dimensional Nonsingular Simulation of Rigid Manipulators by Robert M. Verbos Lieutenant, United States Navy B.E.E., Villanova University, 1981 Submitted in

  3. 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

  4. Sufficient conditions for thermal rectification in general graded materials.

    PubMed

    Pereira, Emmanuel

    2011-03-01

    We address a fundamental problem for the advance of phononics: the search of a feasible thermal diode. We establish sufficient conditions for the existence of thermal rectification in general graded materials. By starting from simple assumptions satisfied by the usual anharmonic models that describe heat conduction in solids, we derive an expression for the rectification. The analytical formula shows how to increase the rectification, and the conditions to avoid its decay with the system size, a problem present in the recurrent model of diodes given by the sequential coupling of two or three different parts. Moreover, for these graded systems, we show that the regimes of nondecaying rectification and of normal conductivity do not overlap. Our results indicate the graded systems as optimal materials for a thermal diode, the basic component of several devices of phononics.

  5. Commentary: is the paradigm for humiliation sufficiently complex?

    PubMed

    Altshul, Victor A

    2010-01-01

    The authors Torres and Bergner present a simple, elegant paradigm for understanding the phenomenon of humiliation. They suggest it may have universal applicability and may be of heuristic value for clinicians and policy-makers involved in forensic and social arenas. They offer case examples to illustrate its utility. It is open to question, however, whether the paradigm is sufficiently complex to encompass all the variables in actual situations. In real life, the evolution of humiliation is a highly complicated, often messy process that takes place over time and often results in intense feelings of humiliation in more than one person, often affecting several persons. The authors' examples are reexamined from alternate assumptions about what may have happened in each case. An additional case example illustrates a high degree of interpersonal complexity, suggesting that actual situations may be too unwieldy to allow for simple analysis by the paradigm.

  6. Variational necessary and sufficient stability conditions for inviscid shear flow

    PubMed Central

    Hirota, M.; Morrison, P. J.; Hattori, Y.

    2014-01-01

    A necessary and sufficient condition for linear stability of inviscid parallel shear flow is formulated by developing a novel variational principle, where the velocity profile is assumed to be monotonic and analytic. It is shown that unstable eigenvalues of Rayleigh's equation (which is a non-self-adjoint eigenvalue problem) can be associated with positive eigenvalues of a certain self-adjoint operator. The stability is therefore determined by maximizing a quadratic form, which is theoretically and numerically more tractable than directly solving Rayleigh's equation. This variational stability criterion is based on the understanding of Kreĭn signature for continuous spectra and is applicable to other stability problems of infinite-dimensional Hamiltonian systems. PMID:25484600

  7. [Vitamin-antioxidant sufficiency of winter sports athletes].

    PubMed

    Beketova, N A; Kosheleva, O V; Pereverzeva, O G; Vrzhesinskaia, O A; Kodentsova, V M; Solntseva, T N; Khanfer'ian, R A

    2013-01-01

    The sufficiency of 169 athletes (six disciplines: bullet shooting, biathlon, bobsleigh, skeleton, freestyle skiing, snowboarding) with vitamins A, E, C, B2, and beta-carotene has been investigated in April-September 2013. All athletes (102 juniors, mean age--18.5 +/- 0.3 years, and 67 adult high-performance athletes, mean age--26.8 +/- 0.7 years) were sufficiently supplied with vitamin A (70.7 +/- 1.7 mcg/dl). Mean blood serum retinol level was 15% higher the upper limit of the norm (80 mcg/dl) in biathletes while median reached 90.9 mcg/dl. Blood serum level of tocopherols (1.22 +/- 0.03 mg/dl), ascorbic acid (1.06 +/- 0.03 mg/dl), riboflavin (7.1 +/- 0.4 ng/ml), and beta-carotene (25.1 +/- 1.7 mcg/dl) was in within normal range, but the incidence of insufficiency of vitamins E, C, B2, and carotenoid among athletes varied in the range of 0-25, 0-17, 15-67 and 42-75%, respectively. 95% of adults and 80% of younger athletes were sufficiently provided with vitamin E. Vitamin E level in blood serum of juniors involved in skeleton and biathlon was lower by 51 and 72% (p < 0.05), than this parameter in adult athletes. Vitamin A, C and B2, and beta-carotene blood serum level did not significantly differ in junior and adult athletes. Women were better supplied with vitamins C, B2, and beta-carotene: a reduced blood serum level of these micronutrients in women was detected 2-3 fold rare (p < 0.10) than among men. Blood serum concentration of vitamin C (1.20 +/- 0.05 mg/dl) and beta-carotene (32.0 +/- 3.9 mcg/dl) in women was greater by 15 and 54% (p < 0.05) than in men. In general, the biathletes were better provided with vitamins compared with other athletes. The vast majority (80%) were optimally provided by all three antioxidants (beta-carotene and vitamins E and C). In other sports, the relative quantity of athletes sufficiently supplied with these essential nutrients did not exceed 56%. The quota of supplied with all antioxidants among bullet shooters (31.1%) and

  8. Hindbrain ghrelin receptor signaling is sufficient to maintain fasting glucose.

    PubMed

    Scott, Michael M; Perello, Mario; Chuang, Jen-Chieh; Sakata, Ichiro; Gautron, Laurent; Lee, Charlotte E; Lauzon, Danielle; Elmquist, Joel K; Zigman, Jeffrey M

    2012-01-01

    The neuronal coordination of metabolic homeostasis requires the integration of hormonal signals with multiple interrelated central neuronal circuits to produce appropriate levels of food intake, energy expenditure and fuel availability. Ghrelin, a peripherally produced peptide hormone, circulates at high concentrations during nutrient scarcity. Ghrelin promotes food intake, an action lost in ghrelin receptor null mice and also helps maintain fasting blood glucose levels, ensuring an adequate supply of nutrients to the central nervous system. To better understand mechanisms of ghrelin action, we have examined the roles of ghrelin receptor (GHSR) expression in the mouse hindbrain. Notably, selective hindbrain ghrelin receptor expression was not sufficient to restore ghrelin-stimulated food intake. In contrast, the lowered fasting blood glucose levels observed in ghrelin receptor-deficient mice were returned to wild-type levels by selective re-expression of the ghrelin receptor in the hindbrain. Our results demonstrate the distributed nature of the neurons mediating ghrelin action.

  9. Providing Sufficient Streamflows in an Era of Competing Demands

    NASA Astrophysics Data System (ADS)

    Gordon, Wendy S.; Mayes, Kevin; Williams, Kathleen

    2009-03-01

    FLOW 2008: Interdisciplinary Solutions to Instream Flow Problems; San Antonio, Texas, 7-9 October 2008; The Instream Flow Council (IFC) held its first-ever conference to forge interdisciplinary solutions to the problem of providing sufficient streamflows for environmental purposes in an era of competing demands for freshwater. Conference participants were drawn from across the United States and Canada and even as far away as China, representing state and provincial fish and wildlife and regulatory agencies, federal agencies including the U.S. Geological Survey and U.S. Environmental Protection Agency, nongovernmental organizations, consultants, industry, academics, and even private citizens. Attendees included biologists, geomorphologists, hydrologists, engineers, attorneys, social scientists, and policy makers. The goals of the meeting were to advance the integration of science and policy related to instream flow and to demonstrate the importance of public dialogue through the engagement of diverse stakeholders in cooperatively solving instream flow problems in the United States and Canada.

  10. Geothermal resource requirements for an energy self-sufficient spaceport

    SciTech Connect

    Kruger, P.; Fioravanti, M.; Duchane, D.; Vaughan, A.

    1997-01-01

    Geothermal resources in the southwestern United States provide an opportunity for development of isolated spaceports with local energy self-sufficiency. Geothermal resources can provide both thermal energy and electrical energy for the spaceport facility infrastructure and production of hydrogen fuel for the space vehicles. In contrast to hydrothermal resources by which electric power is generated for sale to utilities, hot dry rock (HDR) geothermal resources are more wide-spread and can be more readily developed at desired spaceport locations. This paper reviews a dynamic model used to quantify the HDR resources requirements for a generic spaceport and estimate the necessary reservoir size and heat extraction rate. The paper reviews the distribution of HDR resources in southern California and southern New Mexico, two regions where a first developmental spaceport is likely to be located. Finally, the paper discusses the design of a HDR facility for the generic spaceport and estimates the cost of the locally produced power.

  11. Rb1 family mutation is sufficient for sarcoma initiation.

    PubMed

    Liu, Yongqing; Sánchez-Tilló, Ester; Lu, Xiaoqin; Clem, Brian; Telang, Sucheta; Jenson, Alfred B; Cuatrecasas, Miriam; Chesney, Jason; Postigo, Antonio; Dean, Douglas C

    2013-01-01

    It is thought that genomic instability precipitated by Rb1 pathway loss rapidly triggers additional cancer gene mutations, accounting for rapid tumour onset following Rb1 mutation. However, recent whole-genome sequencing of retinoblastomas demonstrated little genomic instability, but instead suggested rapid epigenetic activation of cancer genes. These results raise the possibility that loss of the Rb1 pathway, which is a hallmark of cancers, might be sufficient for cancer initiation. Yet, mutation of the Rb1 family or inactivation of the Rb1 pathway in primary cells has proven insufficient for tumour initiation. Here we demonstrate that traditional nude mouse assays impose an artificial anoikis and proliferation barrier that prevents Rb1 family mutant fibroblasts from initiating tumours. By circumventing this barrier, we show that primary fibroblasts with only an Rb1 family mutation efficiently form sarcomas in nude mice, and a Ras-ZEB1-Akt pathway then causes transition of these tumours to an invasive phenotype.

  12. Centrosome Amplification Is Sufficient to Promote Spontaneous Tumorigenesis in Mammals.

    PubMed

    Levine, Michelle S; Bakker, Bjorn; Boeckx, Bram; Moyett, Julia; Lu, James; Vitre, Benjamin; Spierings, Diana C; Lansdorp, Peter M; Cleveland, Don W; Lambrechts, Diether; Foijer, Floris; Holland, Andrew J

    2017-02-06

    Centrosome amplification is a common feature of human tumors, but whether this is a cause or a consequence of cancer remains unclear. Here, we test the consequence of centrosome amplification by creating mice in which centrosome number can be chronically increased in the absence of additional genetic defects. We show that increasing centrosome number elevated tumor initiation in a mouse model of intestinal neoplasia. Most importantly, we demonstrate that supernumerary centrosomes are sufficient to drive aneuploidy and the development of spontaneous tumors in multiple tissues. Tumors arising from centrosome amplification exhibit frequent mitotic errors and possess complex karyotypes, recapitulating a common feature of human cancer. Together, our data support a direct causal relationship among centrosome amplification, genomic instability, and tumor development.

  13. Using scientifically and statistically sufficient statistics in comparing image segmentations.

    PubMed

    Chi, Yueh-Yun; Muller, Keith E

    2010-01-01

    Automatic computer segmentation in three dimensions creates opportunity to reduce the cost of three-dimensional treatment planning of radiotherapy for cancer treatment. Comparisons between human and computer accuracy in segmenting kidneys in CT scans generate distance values far larger in number than the number of CT scans. Such high dimension, low sample size (HDLSS) data present a grand challenge to statisticians: how do we find good estimates and make credible inference? We recommend discovering and using scientifically and statistically sufficient statistics as an additional strategy for overcoming the curse of dimensionality. First, we reduced the three-dimensional array of distances for each image comparison to a histogram to be modeled individually. Second, we used non-parametric kernel density estimation to explore distributional patterns and assess multi-modality. Third, a systematic exploratory search for parametric distributions and truncated variations led to choosing a Gaussian form as approximating the distribution of a cube root transformation of distance. Fourth, representing each histogram by an individually estimated distribution eliminated the HDLSS problem by reducing on average 26,000 distances per histogram to just 2 parameter estimates. In the fifth and final step we used classical statistical methods to demonstrate that the two human observers disagreed significantly less with each other than with the computer segmentation. Nevertheless, the size of all disagreements was clinically unimportant relative to the size of a kidney. The hierarchal modeling approach to object-oriented data created response variables deemed sufficient by both the scientists and statisticians. We believe the same strategy provides a useful addition to the imaging toolkit and will succeed with many other high throughput technologies in genetics, metabolomics and chemical analysis.

  14. Sufficient penetration of peracetic acid into drilled human femoral heads.

    PubMed

    Brosig, H; Jacker, H-J; Borchert, H-H; Kalus, U; Dörner, T; von Versen, R; Pruss, A

    2005-01-01

    Chemical sterilisation methods for musculoskeletal transplants have the problem of penetration into all tissue strata. The present study examined if a peracetic acid/ethanol solution penetrated to a sufficient extent into specifically prepared femoral heads. To this effect, 10 femoral heads have been provided with drillings (diameter 2 mm, depth 10 mm) at a distance of 15 mm (series B) and placed in a diffusion chamber with sterilisation solution. From an additional central drilling at the femoral neck junction, the sample drawing was made after 30 min each over a period of 4 h for the iodometric determination of peracetic acid (PAA) concentration. Ten femoral heads, which did contain only the central drilling, served as controls (series A). In 9 of the examined femoral heads of series A the defined minimum concentration of PAA of 0.2% (inactivation of bacteria, spores, fungi) has been clearly exceeded over the complete period of measurement. About 0.8% PAA (inactivation of viruses) was achieved within 4 h only with six femoral heads. Nine out of the 10 examined femoral heads in series B show a clearly improved penetration behaviour which was expressed in smaller standard deviations, a faster increase in concentration, as well as in higher starting and final concentrations (approx. 0.9%) of PAA. Previous drying in air leads to a faster penetration into the centre of the bone. Standardised drilling of de-cartilaged femoral heads creates favourable conditions for the penetration of the PAA sterilisation solution into the whole tissue and guarantees a sufficient inactivation of microorganisms.

  15. 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.

  16. Accuracy limit of rigid 3-point water models.

    PubMed

    Izadi, Saeed; Onufriev, Alexey V

    2016-08-21

    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.

  17. An Experiment on the Inertial Properties of a Rigid Body.

    ERIC Educational Resources Information Center

    Armstrong, H. L.

    1985-01-01

    Presents an experiment which focuses on the inertial properties of a rigid body as expressed in terms of principal axes and moments of inertia. Background information, a description of the apparatus needed, and a discussion of results obtained are included. (JN)

  18. 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.

  19. 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...

  20. Integrability of two interactingN-dimensional rigid bodies

    NASA Astrophysics Data System (ADS)

    Perelomov, A. M.; Ragnisco, O.; Wojciechowski, S.

    1985-12-01

    A new class of integrable Euler equations on the Lie algebra so(2n) describing twon-dimensional interacting rigid bodies is found. A Lax representation of equations of motion which depends on a spectral parameter is given and complete integrability is proved. The double hamiltonian structure and the Lax representation of the general flow is discussed.

  1. 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.

  2. Cyanide toxicity from the thermal degradation of rigid polyurethane foam.

    PubMed

    Bell, R H; Stemmer, K L; Barkley, W; Hollingsworth, L D

    1979-09-01

    Thermal degradation products (tdp) from a model, rigid polyurethane foam were collected in such a manner as to eliminate carbon monoxide and other gases with low boiling points. The effects in rats resulting from intratracheal intubation (I.T.) of the tdp are discussed. Cyanide was found to be a major factor associated with severe toxic responses of the experimental rats.

  3. Non-rigid Face Tracking with Local Appearance Consistency Constraint

    PubMed Central

    Wang, Yang; Lucey, Simon; Cohn, Jeffrey F.; Saragih, Jason

    2010-01-01

    In this paper we present a new discriminative approach to achieve consistent and efficient tracking of non-rigid object motion, such as facial expressions. By utilizing both spatial and temporal appearance coherence at the patch level, the proposed approach can reduce ambiguity and increase accuracy. Recent research demonstrates that feature based approaches, such as constrained local models (CLMs), can achieve good performance in non-rigid object alignment/tracking using local region descriptors and a non-rigid shape prior. However, the matching performance of the learned generic patch experts is susceptible to local appearance ambiguity. Since there is no motion continuity constraint between neighboring frames of the same sequence, the resultant object alignment might not be consistent from frame to frame and the motion field is not temporally smooth. In this paper, we extend the CLM method into the spatio-temporal domain by enforcing the appearance consistency constraint of each local patch between neighboring frames. More importantly, we show that the global warp update can be optimized jointly in an efficient manner using convex quadratic fitting. Finally, we demonstrate that our approach receives improved performance for the task of non-rigid facial motion tracking on the videos of clinical patients. PMID:25242852

  4. 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

  5. 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.

  6. [Lens prescription for rigid contact lenses in keratoconus].

    PubMed

    Manea, Georgiana

    2012-01-01

    Rigid Gas-Permeable contact lenses is a less risky option for improving the quality of vision in corneal ectasias such as keratoconus. They reshape the corneal surface (flattens the cornea) so that in most cases, with a proper lens, the patient can reach a visual acuity of 20/20.

  7. 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…

  8. Genus Ranges of 4-Regular Rigid Vertex Graphs.

    PubMed

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

    2015-01-01

    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.

  9. 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

  10. Accuracy limit of rigid 3-point water models

    PubMed Central

    Izadi, Saeed

    2016-01-01

    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. PMID:27544113

  11. Evaluation of Satisfaction and Axial Rigidity with Titan XL Cylinders

    PubMed Central

    Henry, Gerard D.; Jennermann, Caroline; Eid, J. Francois

    2012-01-01

    The inflatable penile prosthesis (IPP) has high patient satisfaction rates and good mechanical reliability rates in multiple studies. The number one patient compliant at six months is penile length. Recently, new technique for aggressive sizing of the cylinders has been published on in the literature. One IPP company has produced a new product that has longer length cylinders (XL) than those available. However, traditionally long cylinders were felt to lack axial rigidity. Therefore, a prospective, multicenter, central IRB-approved, monitored study was performed on the new product to address these concerns. At 2 centers, a total of 17 patients underwent surgical implantation of these new XL cylinders. These patients were questioned for patient satisfaction and tested for axial rigidity using a Fastsize Erectile Quality Monitor. The results showed excellent patient satisfaction rates and great axial rigidity with the Fastsize Erectile Quality Monitor. The XL cylinders appear to give the IPP surgeon the ability to use longer cylinders with good patient satisfaction and great axial rigidity. PMID:22997510

  12. Rigid, Variable-View Endoscope in Neurosurgery: First Intraoperative Experience.

    PubMed

    Ebner, Florian H; Roser, Florian; Roder, Constantin; Tatagiba, Marcos; Schuhmann, Martin U

    2015-08-01

    The endoscope became a highly valued visualization tool in neurosurgery. However, technical limitations caused by the rigidity of current standard endoscopes significantly decrease ergonomy in transcranial neurosurgery. Further technological developments will aid enlarging the surgical applicability. To evaluate the intraoperative features of a rigid variable-view endoscope in neurosurgery. We assessed a 4 mm rigid rod lens endoscope (EndoCAMeleon, Karl Storz, Tuttlingen, Germany) in the intraoperative setting. The device offers a variable angle of view from 15° to 90° in one plane. The endoscope was used in 3 cases (aneurysm clipping, vestibular schwannoma surgery, endoscopic third ventriculostomy) for inspection. Direct insertion of the device through the craniotomy/burr hole with the lowest angled view (15°) was always possible. Neurovascular structures crossing the access route could be visualized and avoided. This allowed a targeted positioning of the endoscope's tip in the operating field. Once the target point was reached, viewing direction was changed in one plane from 15° to 90° according to anatomic demands. As the endoscope's tip does not move while the lens is rotated, surrounding neurovascular structures are not at risk to be injured. However, turning of the lens-controlling wheel in proximity to delicate structures may be inconvenient. The rigid, variable-view endoscope has the potential to become an appreciated visualization tool in neuroendoscopy. The steerable lens enables a tremendous expansion of the visual field, resulting in higher efficiency for surgeons and increased safety for patients. © The Author(s) 2014.

  13. 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... for medical purposes to provide whole body support by means of a pressurized suit to help...

  14. 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... for medical purposes to provide whole body support by means of a pressurized suit to help...

  15. Numerical derivation of forced nutation terms for a rigid earth

    NASA Technical Reports Server (NTRS)

    Schastok, J.; Soffel, M.; Ruder, H.

    1990-01-01

    The results of a numerical integration of the Euler equations for a rigid earth model covering a time span of 250 years are compared with Kinoshita's (1977) theory for the forced nutations and with a new nutation series by Kinoshita and Souchay. Numerical corrections to some of the analytically derived nutation terms are presented.

  16. 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.

  17. 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...

  18. The rigid-flexible nonlinear robotic manipulator: Modeling and control

    NASA Astrophysics Data System (ADS)

    Fenili, André; Balthazar, José Manoel

    2011-05-01

    The State-Dependent Riccati Equation (SDRE) control of a nonlinear rigid-flexible two link robotic manipulator is investigated. Different cases are considered assuming small deviations and large deviations from the desired final states. The nonlinear governing equations of motion are coupled, providing considerable excitation of all the nonlinear terms. The results present satisfactory final states but also undesirable overshoot.

  19. Rigid and elastic registration for coronary artery IVUS images.

    PubMed

    Sun, Zheng; Bai, Hua; Liu, Bingru

    2016-04-29

    Intravascular ultrasound (IVUS) has been widely used in diagnosis and interventional treatment of cardiac vessel diseases. The coronary artery IVUS images are usually polluted by motion artifacts caused by cardiac motion, pulsatile blood and catheter twist during continuous pullback acquisition. Strategies for rigid and elastic registration of coronary artery IVUS studies are developed to suppress the longitudinal motion and misalignment between successive frames. Rigid registration is performed by searching for the optimal matching for each frame in other cycles based on the cyclic variation of gray-scale features. The image sequence is gated to properly identify the frames in each cardiac phase. Then, elastic registration between frames is achieved through an optimization algorithm based on thin plate spline (TPS) to correct the misalignment of successive slices. Experimental results with in vivo image data shows that the rigid registration performs better than the offline ECG gating. The elastic mapping relation between lumen contours in successive frames is smooth and continuous. The serrated vessel wall borders in longitudinal cuts are smoothed after rigid registration while image segmentation and feature extraction are required. The point-to-point correspondence between lumen contours detected from two matched frames is obtained with elastic registration.

  20. 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

  1. Design of the new rigid endoscope distortion measurement system

    NASA Astrophysics Data System (ADS)

    Zhai, Xiaohao; Liu, Xiaohua; Liu, Ming; Hui, Mei; Dong, Liquan; Zhao, Yuejin; Wang, Yakun; Li, Yonghui; Zhou, Peng

    2015-08-01

    Endoscopic imaging quality affects industrial safety and medical security. Rigid endoscope distortion is of great signification as one of optical parameters to evaluate the imaging quality. This paper introduces a new method of rigid endoscope distortion measurement, which is different from the common methods with low accuracy and fussy operation. It contains a Liquid Crystal Display (LCD) to display the target, a CCD to obtain the images with distortion, and a computer to process the images. The LCD is employed instead of common white screen. The autonomous control system of LCD makes it showing the test target designed for distortion, and its parameter is known. LCD control system can change the test target to satisfy the different demand for accuracy, which avoids replacing target frequently. The test system also contains a CCD to acquire images in the exit pupil position of rigid endoscope. Rigid endoscope distortion is regarded as centrosymmetric, and the MATLAB software automatically measures it by processing the images from CCD. The MATLAB software compares target images with that without distortion on LCD and calculates the results. Relative distortion is obtained at different field of view (FOV) radius. The computer plots the curve of relative distortion, abscissa means radius of FOV, ordinate means relative distortion. The industry standard shows that, the distortion at 70% field of view is pointed on the curve, which can be taken as an evaluation standard. This new measuring method achieves advantages of high precision, high degree of intelligence, excellent repeatability and gets calculation results quickly.

  2. GELATIN RIGIDIZED EXPANDABLE SANDWICH SOLAR ENERGY CONCENTRATORS AND SPACE STRUCTURES

    DTIC Science & Technology

    compatible and equally resistant to a space environment. The final items of the development program were lightweight, self-rigidizing, 10-foot diameter solar ... energy concentrators; and 4-foot diameter cylinders, 8-foot long. Space systems considerations were an integral part of this study, with particular emphasis on much larger structures requirements.

  3. Origin of Unusually High Rigidity in Selected Helical Coil Structures

    NASA Astrophysics Data System (ADS)

    Tománek, David; Every, Arthur G.

    2017-07-01

    Using continuum elasticity theory, we describe the elastic behavior of helical coils with an asymmetric double-helix structure and identify conditions under which they become very rigid. Theoretical insight gained for macrostructures including a stretched telephone cord and an unsupported helical staircase is universal and of interest for the elastic behavior of helical structures on the micrometer and nanometer scale.

  4. 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.

  5. Bending rigidity of type I collagen homotrimer fibrils

    NASA Astrophysics Data System (ADS)

    Han, Sejin; Leikin, Sergey; Losert, Wolfgang

    2009-03-01

    Normal type I collagen is an α1(I)2α2(I) heterotrimeric triple helix, but α1(I)3 homotrimers are also found in fetal tissues and various pathological conditions, e.g., causing bone fragility and reducing tendon tensile strength. It remains unclear whether homotrimers alter mechanical properties of individual fibrils or affect tissues by altering their organization at a higher level. To address this question, we investigated how homotrimers affect fibril bending rigidity. Homotrimer fibrils have been shown to be more loosely packed so that we expected them to be more susceptible to bending. However, homotrimer fibrils were more rigid despite being thinner and more hydrated. To quantify fibril rigidity, we analyzed their shape by Fourier decomposition, determined the correlation function for the direction along each fibril, and calculated the distribution of local fibril curvature. The estimated persistence length of homotrimer fibrils was 3 ˜ 10 times longer than for heterotrimer fibrils, indicating much higher bending rigidity of homotrimer fibrils.

  6. 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…

  7. “Mind the Trap”: Mindfulness Practice Reduces Cognitive Rigidity

    PubMed Central

    Greenberg, Jonathan; Reiner, Keren; Meiran, Nachshon

    2012-01-01

    Two experiments examined the relation between mindfulness practice and cognitive rigidity by using a variation of the Einstellung water jar task. Participants were required to use three hypothetical jars to obtain a specific amount of water. Initial problems were solvable by the same complex formula, but in later problems (“critical” or “trap” problems) solving was possible by an additional much simpler formula. A rigidity score was compiled through perseverance of the complex formula. In Experiment 1, experienced mindfulness meditators received significantly lower rigidity scores than non-meditators who had registered for their first meditation retreat. Similar results were obtained in randomized controlled Experiment 2 comparing non-meditators who underwent an eight meeting mindfulness program with a waiting list group. The authors conclude that mindfulness meditation reduces cognitive rigidity via the tendency to be “blinded” by experience. Results are discussed in light of the benefits of mindfulness practice regarding a reduced tendency to overlook novel and adaptive ways of responding due to past experience, both in and out of the clinical setting. PMID:22615758

  8. Rigidity versus flexibility: the dilemma of understanding protein thermal stability.

    PubMed

    Karshikoff, Andrey; Nilsson, Lennart; Ladenstein, Rudolf

    2015-10-01

    The role of fluctuations in protein thermostability has recently received considerable attention. In the current literature a dualistic picture can be found: thermostability seems to be associated with enhanced rigidity of the protein scaffold in parallel with the reduction of flexible parts of the structure. In contradiction to such arguments it has been shown by experimental studies and computer simulation that thermal tolerance of a protein is not necessarily correlated with the suppression of internal fluctuations and mobility. Both concepts, rigidity and flexibility, are derived from mechanical engineering and represent temporally insensitive features describing static properties, neglecting that relative motion at certain time scales is possible in structurally stable regions of a protein. This suggests that a strict separation of rigid and flexible parts of a protein molecule does not describe the reality correctly. In this work the concepts of mobility/flexibility versus rigidity will be critically reconsidered by taking into account molecular dynamics calculations of heat capacity and conformational entropy, salt bridge networks, electrostatic interactions in folded and unfolded states, and the emerging picture of protein thermostability in view of recently developed network theories. Last, but not least, the influence of high temperature on the active site and activity of enzymes will be considered. © 2015 FEBS.

  9. 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 (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5020 External penile...

  10. 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 (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5020 External penile...

  11. Importance of axial penile rigidity in objective evaluation of erection quality in patients with erectile dysfunction--comparison with radial rigidity.

    PubMed

    Mizuno, Ichiro; Komiya, Akira; Watanabe, Akihiko; Fuse, Hideki

    2010-01-01

    The aim of this prospective study was to evaluate the usefulness of measurement of axial penile rigidity, compared with radial penile rigidity. Twenty-two patients, aged 21-75 years old (a mean of 50), with erectile dysfunction underwent axial penile rigidity measurements by the digital inflection rigidometer (DIR) as well as radial penile rigidity measurements by the RigiScan Plus during intracavernous pharmacological erection testing. A significant correlation was recognized between axial rigidity, and radial rigidity at the tip (p = 0.0024) and base (p = 0.0098) of the penis. In 10 patients, the DIR revealed axial rigidity of 550 g or more, and they also had radial rigidity of 60% or more at the tip and base. In 14 and 17 subjects, radial rigidity of 60% or more was observed at the tip and base, respectively. Four of the former 14 and 7 of the latter 17 had axial rigidity <550 g. A RigiScan results of radial rigidity of 60% or more should be interpreted cautiously and not necessarily regarded as normal. Copyright (c) 2010 S. Karger AG, Basel.

  12. Substrates with engineered step changes in rigidity induce traction force polarity and durotaxis.

    PubMed

    Breckenridge, Mark T; Desai, Ravi A; Yang, Michael T; Fu, Jianping; Chen, Christopher S

    2014-03-01

    Rigidity sensing plays a fundamental role in multiple cell functions ranging from migration, to proliferation and differentiation(1-5). During migration, single cells have been reported to preferentially move toward more rigid regions of a substrate in a process termed durotaxis. Durotaxis could contribute to cell migration in wound healing and gastrulation, where local gradients in tissue rigidity have been described. Despite the potential importance of this phenomenon to physiology and disease, it remains unclear how rigidity guides these behaviors and the underlying cellular and molecular mechanisms. To investigate the functional role of subcellular distribution and dynamics of cellular traction forces during durotaxis, we developed a unique microfabrication strategy to generate elastomeric micropost arrays patterned with regions exhibiting two different rigidities juxtaposed next to each other. After initial cell attachment on the rigidity boundary of the micropost array, NIH 3T3 fibroblasts were observed to preferentially migrate toward the rigid region of the micropost array, indicative of durotaxis. Additionally, cells bridging two rigidities across the rigidity boundary on the micropost array developed stronger traction forces on the more rigid side of the substrate indistinguishable from forces generated by cells exclusively seeded on rigid regions of the micropost array. Together, our results highlighted the utility of step-rigidity micropost arrays to investigate the functional role of traction forces in rigidity sensing and durotaxis, suggesting that cells could sense substrate rigidity locally to induce an asymmetrical intracellular traction force distribution to contribute to durotaxis.

  13. India's baseline plan for nuclear energy self-sufficiency.

    SciTech Connect

    Bucher, R .G.; Nuclear Engineering Division

    2009-01-01

    India's nuclear energy strategy has traditionally strived for energy self-sufficiency, driven largely by necessity following trade restrictions imposed by the Nuclear Suppliers Group (NSG) following India's 'peaceful nuclear explosion' of 1974. On September 6, 2008, the NSG agreed to create an exception opening nuclear trade with India, which may create opportunities for India to modify its baseline strategy. The purpose of this document is to describe India's 'baseline plan,' which was developed under constrained trade conditions, as a basis for understanding changes in India's path as a result of the opening of nuclear commerce. Note that this treatise is based upon publicly available information. No attempt is made to judge whether India can meet specified goals either in scope or schedule. In fact, the reader is warned a priori that India's delivery of stated goals has often fallen short or taken a significantly longer period to accomplish. It has been evident since the early days of nuclear power that India's natural resources would determine the direction of its civil nuclear power program. It's modest uranium but vast thorium reserves dictated that the country's primary objective would be thorium utilization. Estimates of India's natural deposits vary appreciably, but its uranium reserves are known to be extremely limited, totaling approximately 80,000 tons, on the order of 1% of the world's deposits; and nominally one-third of this ore is of very low uranium concentration. However, India's roughly 300,000 tons of thorium reserves account for approximately 30% of the world's total. Confronted with this reality, the future of India's nuclear power industry is strongly dependent on the development of a thorium-based nuclear fuel cycle as the only way to insure a stable, sustainable, and autonomous program. The path to India's nuclear energy self-sufficiency was first outlined in a seminal paper by Drs. H. J. Bhabha and N. B. Prasad presented at the Second

  14. Initial development of an electronic testis rigidity tester.

    PubMed

    Mirilas, Petros; Tsakiridis, Odysseus

    2011-03-22

    We aimed to develop our previously presented mechanical device, the Testis Rigidity Tester (TRT), into an electronic system (Electronic Testis Rigidity Tester, ETRT) by applying tactile imaging, which has been used successfully with other solid organs. A measuring device, located at the front end of the ETRT incorporates a tactile sensor comprising an array of microsensors. By application of a predetermined deformation of 2 mm, increased pressure alters linearly the resistance of each microsensor, producing changes of voltage. These signals were amplified, filtered, and digitized, and then processed by an electronic collector system, which presented them as a color-filled contour plot of the area of the testis coming into contact with the sensor. Testis models of different rigidity served for initial evaluation of ETRT; their evacuated central spaces contained different, increasing glue masses. An independent method of rigidity measurement, using an electric weight scale and a micrometer, showed that the more the glue injected, the greater the force needed for a 2-mm deformation. In a preliminary test, a single sensor connected to a multimeter showed similar force measurement for the same deformation in these phantoms. For each of the testis models compressed in the same manner, the ETRT system offered a map of pressures, represented by a color scale within the contour plot of the contact area with the sensor. ETRT found certain differences in rigidity between models that had escaped detection by a blind observer. ETRT is easy to use and provides a color-coded "insight" of the testis internal structure. After experimental testing, it could be valuable in intraoperative evaluation of testes, so that the surgeon can decide about orchectomy or orcheopexy.

  15. Deformable registration of multi-modal data including rigid structures

    SciTech Connect

    Huesman, Ronald H.; Klein, Gregory J.; Kimdon, Joey A.; Kuo, Chaincy; Majumdar, Sharmila

    2003-05-02

    Multi-modality imaging studies are becoming more widely utilized in the analysis of medical data. Anatomical data from CT and MRI are useful for analyzing or further processing functional data from techniques such as PET and SPECT. When data are not acquired simultaneously, even when these data are acquired on a dual-imaging device using the same bed, motion can occur that requires registration between the reconstructed image volumes. As the human torso can allow non-rigid motion, this type of motion should be estimated and corrected. We report a deformation registration technique that utilizes rigid registration for bony structures, while allowing elastic transformation of soft tissue to more accurately register the entire image volume. The technique is applied to the registration of CT and MR images of the lumbar spine. First a global rigid registration is performed to approximately align features. Bony structures are then segmented from the CT data using semi-automated process, and bounding boxes for each vertebra are established. Each CT subvolume is then individually registered to the MRI data using a piece-wise rigid registration algorithm and a mutual information image similarity measure. The resulting set of rigid transformations allows for accurate registration of the parts of the CT and MRI data representing the vertebrae, but not the adjacent soft tissue. To align the soft tissue, a smoothly-varying deformation is computed using a thin platespline(TPS) algorithm. The TPS technique requires a sparse set of landmarks that are to be brought into correspondence. These landmarks are automatically obtained from the segmented data using simple edge-detection techniques and random sampling from the edge candidates. A smoothness parameter is also included in the TPS formulation for characterization of the stiffness of the soft tissue. Estimation of an appropriate stiffness factor is obtained iteratively by using the mutual information cost function on the result

  16. 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

  17. How rigid is a rigid plate? Geodetic constraint from the TrigNet CGPS network, South Africa

    NASA Astrophysics Data System (ADS)

    Malservisi, Rocco; Hugentobler, Urs; Wonnacott, Richard; Hackl, Matthias

    2013-03-01

    Rigidity and continuity of the Nubia plate is a fundamental assumption for the kinematic description, the dynamic implications of its interaction with surrounding plates and ultimately an important constraint to the geodynamics processes involved in continental lithospheric rupture. Geophysical, neotectonic and geodynamics considerations suggest the possibility that the Nubia plate is not completely rigid but could be undergoing internal deformation due to the southward propagation of the East African Rift. Here, we utilize the South African TrigNet geodetic network to evaluate the amount of internal deformation within the South African region and the possibility of motion between South Africa and the rest of the African continent. Our results show that the South African region behaves rigidly, with deformation of the order of 1 nanostrain yr-1 or less. The analysis shows some higher strain rates in the eastern region, and the presence of spatially correlated residuals in the Cape Town region and the region east of Johannesburg. Although not statistically significant, the spatial coherence of those residuals could indicate tectonic activity. A comparison of the Euler vector for the South African region with previously published Euler poles for the Nubia plate as well as the analysis of the residuals of Nubia sites with respect to a `rigid' TrigNet are compatible with clockwise rotation of the South African block with respect to the African continent, consistent with a propagation of the East Africa Rift along the Okavango region.

  18. On necessity and sufficiency in counseling and psychotherapy (revisited).

    PubMed

    Lazarus, Arnold A

    2007-09-01

    It seems to me that Carl Rogers (see record 2007-14639-002) was far too ambitious in trying to specify general conditions of necessity and sufficiency that would be relevant to the entire spectrum of problems and the diverse expectancies and personalities of the people who seek our help. Rogers' position and orientation almost totally overlook the array of problems under the rubric of "response deficits" that stem from misinformation and missing information and call for active correction, training, and retraining. Rogers also paid scant attention to problems with significant biological determinants. Nevertheless, as exemplified by his seminal 1957 article and many other articles and books, Rogers made major contributions within the domain of the therapeutic alliance. Today, the scientific emphasis looks at accountability, the need to establish various treatments of choice, and the need to understand their presumed mechanisms. Treatment efficacy and generalizability across different methodologies are now considered key issues. The efficacy narrowing and clinically self-limiting consequences of adhering to one particular school of thought are now self-evident to most. (PsycINFO Database Record (c) 2010 APA, all rights reserved).

  19. The B chain of PDGF alone is sufficient for mitogenesis.

    PubMed

    Kelly, J D; Raines, E W; Ross, R; Murray, M J

    1985-12-16

    The platelet-derived growth factor (PDGF) is a mitogen derived from human platelets consisting of two related polypeptides termed A and B chains. The entire B chain of PDGF is highly (96%) homologous to a portion of p28sis, the transforming protein of simian sarcoma virus. It has been suggested that p28sis exerts its transforming potential by mimicking the growth promoting activity of PDGF and stimulating the cell in an autocrine manner. We have directly examined the mitogenic potential of p28sis and the B chain homologous region by expressing these heterologous sequences in the yeast Saccharomyces cerevisiae. In our constructions, these proteins are encoded by portions of the v-sis gene. Expression and secretion from the yeast cell is achieved by using a yeast promoter and the alpha-factor pheromone secretory leader. The sis proteins thus expressed and secreted are immunoreactive with anti-PDGF antisera and are mitogenic for cultured fibroblasts. Furthermore, they mediate this mitogenic activity by specific binding to the PDGF cell surface receptor. Gel electrophoresis and cell binding analysis indicates that the mitogenic species is primarily a disulphide-bonded dimer. We are able to conclude that p28sis is a mitogen and that a polypeptide corresponding to the B chain alone is sufficient to account for the mitogenic activity attributed to PDGF.

  20. Stochasticity, spikes and decoding: sufficiency and utility of order statistics.

    PubMed

    Richmond, Barry J

    2009-06-01

    For over 75 years it has been clear that the number of spikes in a neural response is an important part of the neuronal code. Starting as early as the 1950's with MacKay and McCullough, there has been speculation over whether each spike and its exact time of occurrence carry information. Although it is obvious that the firing rate carries information it has been less clear as to whether there is information in exactly timed patterns, when they arise from the dynamics of the neurons and networks, as opposed to when they represent some strong external drive that entrains them. One strong null hypothesis that can be applied is that spike trains arise from stochastic sampling of an underlying deterministic temporally modulated rate function, that is, there is a time-varying rate function. In this view, order statistics seem to provide a sufficient theoretical construct to both generate simulated spike trains that are indistinguishable from those observed experimentally, and to evaluate (decode) the data recovered from experiments. It remains to learn whether there are physiologically important signals that are not described by such a null hypothesis.

  1. The Generalized Asymptotic Equipartition Property: Necessary and Sufficient Conditions

    PubMed Central

    Harrison, Matthew T.

    2011-01-01

    Suppose a string X1n=(X1,X2,…,Xn) generated by a memoryless source (Xn)n≥1 with distribution P is to be compressed with distortion no greater than D ≥ 0, using a memoryless random codebook with distribution Q. The compression performance is determined by the “generalized asymptotic equipartition property” (AEP), which states that the probability of finding a D-close match between X1n and any given codeword Y1n, is approximately 2−nR(P, Q, D), where the rate function R(P, Q, D) can be expressed as an infimum of relative entropies. The main purpose here is to remove various restrictive assumptions on the validity of this result that have appeared in the recent literature. Necessary and sufficient conditions for the generalized AEP are provided in the general setting of abstract alphabets and unbounded distortion measures. All possible distortion levels D ≥ 0 are considered; the source (Xn)n≥1 can be stationary and ergodic; and the codebook distribution can have memory. Moreover, the behavior of the matching probability is precisely characterized, even when the generalized AEP is not valid. Natural characterizations of the rate function R(P, Q, D) are established under equally general conditions. PMID:21614133

  2. Abundant Inverse Regression using Sufficient Reduction and its Applications

    PubMed Central

    Kim, Hyunwoo J.; Smith, Brandon M.; Adluru, Nagesh; Dyer, Charles R.; Johnson, Sterling C.; Singh, Vikas

    2016-01-01

    Statistical models such as linear regression drive numerous applications in computer vision and machine learning. The landscape of practical deployments of these formulations is dominated by forward regression models that estimate the parameters of a function mapping a set of p covariates, x, to a response variable, y. The less known alternative, Inverse Regression, offers various benefits that are much less explored in vision problems. The goal of this paper is to show how Inverse Regression in the “abundant” feature setting (i.e., many subsets of features are associated with the target label or response, as is the case for images), together with a statistical construction called Sufficient Reduction, yields highly flexible models that are a natural fit for model estimation tasks in vision. Specifically, we obtain formulations that provide relevance of individual covariates used in prediction, at the level of specific examples/samples — in a sense, explaining why a particular prediction was made. With no compromise in performance relative to other methods, an ability to interpret why a learning algorithm is behaving in a specific way for each prediction, adds significant value in numerous applications. We illustrate these properties and the benefits of Abundant Inverse Regression (AIR) on three distinct applications. PMID:27796010

  3. Mammary hypoplasia: not every breast can produce sufficient milk.

    PubMed

    Arbour, Megan W; Kessler, Julia Lange

    2013-01-01

    Breast milk is considered the optimal form of nutrition for newborn infants. Current recommendations are to breastfeed for 6 months. Not all women are able to breastfeed. Mammary hypoplasia is a primary cause of failed lactogenesis II, whereby the mother is unable to produce an adequate milk volume. Women with mammary hypoplasia often have normal hormone levels and innervation but lack sufficient glandular tissue to produce an adequate milk supply to sustain their infant. The etiology of this rare condition is unclear, although there are theories that refer to genetic predisposition and estrogenic environmental exposures in select agricultural environments. Women with mammary hypoplasia may not exhibit the typical breast changes associated with pregnancy and may fail to lactate postpartum. Breasts of women with mammary hypoplasia may be widely spaced (1.5 inches or greater), asymmetric, or tuberous in nature. Awareness of the history and clinical signs of mammary hypoplasia during the prenatal period and immediate postpartum increases the likelihood that women will receive the needed education and physical and emotional support and encouragement. Several medications and herbs demonstrate some efficacy in increasing breast milk production in women with mammary hypoplasia.

  4. Pen-2 and Presenilin are Sufficient to Catalyze Notch Processing.

    PubMed

    Hu, Chen; Xu, Junjie; Zeng, Linlin; Li, Ting; Cui, Mei-Zhen; Xu, Xuemin

    2017-01-01

    Presenilin-1 (PS1) or presenilin-2 (PS2), nicastrin (NCT), anterior pharynx-defective 1 (Aph-1), and presenilin enhancer-2 (Pen-2) have been considered the minimal essential subunits required to form an active γ-secretase complex. Besides PS, which has been widely believed to function as the catalytic subunit of the complex, the functional roles of the other subunits in the γ-secretase complex remain debatable. In the current study, we set out to determine the role of Pen-2 in γ-secretase activity. To this end, using knockout cells in combination with siRNA and immunoprecipitation approaches, our results revealed that Pen-2 together with presenilin are sufficient to form a functionally active enzyme to process Notch. Specifically, our data demonstrated that Pen-2 plays a crucial role in substrate binding, a mechanism by which Pen-2 contributes directly to the catalytic mechanism of γ-secretase activity. Our data also suggested that there may be different requirements for components to process AβPP and Notch. This information would be important for therapeutic strategy aimed at inhibition or modulation of γ-secretase activity.

  5. Predator confusion is sufficient to evolve swarming behaviour

    PubMed Central

    Olson, Randal S.; Hintze, Arend; Dyer, Fred C.; Knoester, David B.; Adami, Christoph

    2013-01-01

    Swarming behaviours in animals have been extensively studied owing to their implications for the evolution of cooperation, social cognition and predator–prey dynamics. An important goal of these studies is discerning which evolutionary pressures favour the formation of swarms. One hypothesis is that swarms arise because the presence of multiple moving prey in swarms causes confusion for attacking predators, but it remains unclear how important this selective force is. Using an evolutionary model of a predator–prey system, we show that predator confusion provides a sufficient selection pressure to evolve swarming behaviour in prey. Furthermore, we demonstrate that the evolutionary effect of predator confusion on prey could in turn exert pressure on the structure of the predator's visual field, favouring the frontally oriented, high-resolution visual systems commonly observed in predators that feed on swarming animals. Finally, we provide evidence that when prey evolve swarming in response to predator confusion, there is a change in the shape of the functional response curve describing the predator's consumption rate as prey density increases. Thus, we show that a relatively simple perceptual constraint—predator confusion—could have pervasive evolutionary effects on prey behaviour, predator sensory mechanisms and the ecological interactions between predators and prey. PMID:23740485

  6. Ultra-low wear rates for rigid-on-rigid bearings in total hip replacements.

    PubMed

    Clarke, I C; Good, V; Williams, P; Schroeder, D; Anissian, L; Stark, A; Oonishi, H; Schuldies, J; Gustafson, G

    2000-01-01

    With the increased clinical interest in metal-on-metal and ceramic-on-ceramic total-hip replacements (THRs), the objective of this hip simulator study was to identify the relative wear ranking of three bearing systems, namely CoCr-polyethylene (M-PE), CoCr-CoCr (M-M) and ceramic-on-ceramic (C-C). Volumetric wear rates were used as the method of comparison. The seven THR groupings included one M-PE study, two M-M studies and four C-C studies. Special emphasis was given to defining the 'run-in' phase of accelerated wear that rigid-on-rigid bearings generally exhibit. The hypothesis was that characterization of the run-in and steady state wear phases would clarify not only the tribological performance in vitro but also help correlate these in vitro wear rates with the 'average' wear rates measured on retrieved implants. The implant systems were studied on multichannel hip simulators using the Paul gait cycle and bovine serum as the lubricant. With 28 mm CoCr heads, the PE (2.5 Mrad/N2) wear rates averaged 13 mm3/10(6) cycles duration. This was considered a low value compared with the clinical model of 74 mm3/year (for 28 mm heads). Our later studies established that this low laboratory value was a consequence of the serum parameters then in use. The mating CoCr heads (with PE cups) wore at the steady state rate of 0.028 mm3/10(6) cycles. The concurrently run Metasul M-M THRs wore at the steady state rate of 0.119 mm3/10(6) cycles with high-protein serum. In the second Metasul M-M study with low-protein serum, the THR run-in rate was 2.681 mm3/10(6) cycles and steady state was 0.977 mm3/10(6) cycles. At 10 years, these data would predict a 70-fold reduction in M-M wear debris compared with the clinical PE wear model. All M-M implants exhibited biphasic wear trends, with the transition point at 0.5 x 10(6) cycles between run-in and steady state phases, the latter averaging a 3-fold decrease in wear rate. White surface coatings on implants (coming from the serum solution

  7. Investigation of the Rigid Amorphous Fraction in Nylon-6

    SciTech Connect

    Chen,H.; Cebe, P.

    2007-01-01

    A three-phase model, comprising crystalline, mobile amorphous, and rigid amorphous fractions (X{sub c}, X{sub MA}, X{sub rA}, respectively) has been applied in the study of semicrystalline Nylon-6. The samples studied were Nylon-6 alpha phase prepared by subsequent annealing of a parent sample slowly cooled from the melt. The treated samples were annealed at 110 C, then briefly heated to 136 C, then re-annealed at 110 C. Temperature-modulated differential scanning calorimetry (TMDSC) measurements allow the devitrification of the rigid amorphous fraction to be examined. We observe a lower endotherm, termed the 'annealing' peak in the non-reversing heat flow after annealing at 110 C. By brief heating above this lower endotherm and immediately quenching in LN{sub 2}-cooled glass beads, the glass transition temperature and X{sub RA} decrease substantially, X{sub MA} increases, and the annealing peak disappears. The annealing peak corresponds to the point at which partial de-vitrification of the rigid amorphous fraction (RAF) occurs. Re-annealing at 110 C causes the glass transition and X{sub RA} to increase, and X{sub MA} to decrease. None of these treatments affected the measured degree of crystallinity, but it cannot be excluded that crystal reorganization or recrystallization may also occur at the annealing peak, contributing to the de-vitrification of the rigid amorphous fraction. Using a combined approach of thermal analysis with wide and small angle X-ray scattering, we analyze the location of the rigid amorphous and mobile amorphous fractions within the context of the Heterogeneous and Homogeneous Stack Models. Results show the homogeneous stack model is the correct one for Nylon-6. The cooperativity length ({var_epsilon}{sub A}) increases with a decrease of rigid amorphous fraction, or, increase of the mobile amorphous fraction. Devitrification of some of the RAF leads to the broadening of the glass transition region and shift of T{sub g}.

  8. 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

  9. 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

  10. Greater learnability is not sufficient to produce cultural universals

    PubMed Central

    Rafferty, Anna N.; Griffiths, Thomas L.; Ettlinger, Marc

    2013-01-01

    Looking across human societies reveals regularities in the languages that people speak and the concepts that they use. One explanation that has been proposed for these “cultural universals” is differences in the ease with which people learn particular languages and concepts. A difference in learnability means that languages and concepts possessing a particular property are more likely to be accurately transmitted from one generation of learners to the next. Intuitively, this difference could allow languages and concepts that are more learnable to become more prevalent after multiple generations of cultural transmission. If this is the case, the prevalence of languages and concepts with particular properties can be explained simply by demonstrating empirically that they are more learnable. We evaluate this argument using mathematical analysis and behavioral experiments. Specifically, we provide two counter-examples that show how greater learnability need not result in a property becoming prevalent. First, more learnable languages and concepts can nonetheless be less likely to be produced spontaneously as a result of transmission failures. We simulated cultural transmission in the laboratory to show that this can occur for memory of distinctive items: these items are more likely to be remembered, but not generated spontaneously once they have been forgotten. Second, when there are many languages or concepts that lack the more learnable property, sheer numbers can swamp the benefit produced by greater learnability. We demonstrate this using a second series of experiments involving artificial language learning. Both of these counter-examples show that simply finding a learnability bias experimentally is not sufficient to explain why a particular property is prevalent in the languages or concepts used in human societies: explanations for cultural universals based on cultural transmission need to consider the full set of hypotheses a learner could entertain and all

  11. [Effect of vitamin sufficiency on adaptation syndrome in growing rats].

    PubMed

    Sidorova, Iu S; Beketova, N A; Vrzhesinskaia, O A; Kodentsova, V M; Kosheleva, O V; Zorin, S N; Selifanov, A V; Mazo, V K

    2014-01-01

    The influence of vitamin supply of growing male -Wistar rats (n=21) with an initial body weight 53,5±0,9 g on their resistance to a single distress induced by the electric shock has been investigated. Control rats within 21 days received a complete semisynthetic diet,providingadequate amounts of vitamins. Combined vitamin deficiency in experimental rats was caused by 5-fold decrease of vitamin mixture amount in the feed and the total vitamin E exclusion from the mixture. On the 21st day, one day before the end of the experiment, both groups of rats were subjected to stress impact (electrocutaneous irritation on paws, 0,4 mA for 8 sec) and then animals were placed in metabolic cages to collect urine. By the end of the experiment, the animals with the combined vitamin deficiency lag behind in growth. Vitamin B2, A, B1 and E liver content decreased in experimental rats by 1,6, 2,3, 4,4 and 15 fold accordingly. Retinol plasma concentration was significantly reduced by 18%, α-tocopherol level - by 5 fold, urinary excretionof riboflavin and 4-pyridoxic acid (vitamin B6 metabolite) was significantly reduced by 6,5 and 2,46 times accordingly. MDA blood plasma concentration and the urinary ratio of oxidized and not oxidized form of 8-hydroxy-2'-deoxy-guanosine did not differ in both groups of rats. Urinary excretion of stress biomarker corticosterone in rats with combined vitamin deficit was 2,5-fold higher than in control rats. Thus, reducing of vitamins supply resulted in an increase of urine corticosterone in stressed rats, that characterized the intensity of general adaptation syndrome. This fact shows the importance of optimal sufficiency with vitamins in nonspecific (general) resistance to stress.

  12. Increasing adult hippocampal neurogenesis is sufficient to improve pattern separation.

    PubMed

    Sahay, Amar; Scobie, Kimberly N; Hill, Alexis S; O'Carroll, Colin M; Kheirbek, Mazen A; Burghardt, Nesha S; Fenton, André A; Dranovsky, Alex; Hen, René

    2011-04-28

    Adult hippocampal neurogenesis is a unique form of neural circuit plasticity that results in the generation of new neurons in the dentate gyrus throughout life. Neurons that arise in adults (adult-born neurons) show heightened synaptic plasticity during their maturation and can account for up to ten per cent of the entire granule cell population. Moreover, levels of adult hippocampal neurogenesis are increased by interventions that are associated with beneficial effects on cognition and mood, such as learning, environmental enrichment, exercise and chronic treatment with antidepressants. Together, these properties of adult neurogenesis indicate that this process could be harnessed to improve hippocampal functions. However, despite a substantial number of studies demonstrating that adult-born neurons are necessary for mediating specific cognitive functions, as well as some of the behavioural effects of antidepressants, it is unknown whether an increase in adult hippocampal neurogenesis is sufficient to improve cognition and mood. Here we show that inducible genetic expansion of the population of adult-born neurons through enhancing their survival improves performance in a specific cognitive task in which two similar contexts need to be distinguished. Mice with increased adult hippocampal neurogenesis show normal object recognition, spatial learning, contextual fear conditioning and extinction learning but are more efficient in differentiating between overlapping contextual representations, which is indicative of enhanced pattern separation. Furthermore, stimulation of adult hippocampal neurogenesis, when combined with an intervention such as voluntary exercise, produces a robust increase in exploratory behaviour. However, increasing adult hippocampal neurogenesis alone does not produce a behavioural response like that induced by anxiolytic agents or antidepressants. Together, our findings suggest that strategies that are designed to increase adult hippocampal

  13. Greater learnability is not sufficient to produce cultural universals.

    PubMed

    Rafferty, Anna N; Griffiths, Thomas L; Ettlinger, Marc

    2013-10-01

    Looking across human societies reveals regularities in the languages that people speak and the concepts that they use. One explanation that has been proposed for these "cultural universals" is differences in the ease with which people learn particular languages and concepts. A difference in learnability means that languages and concepts possessing a particular property are more likely to be accurately transmitted from one generation of learners to the next. Intuitively, this difference could allow languages and concepts that are more learnable to become more prevalent after multiple generations of cultural transmission. If this is the case, the prevalence of languages and concepts with particular properties can be explained simply by demonstrating empirically that they are more learnable. We evaluate this argument using mathematical analysis and behavioral experiments. Specifically, we provide two counter-examples that show how greater learnability need not result in a property becoming prevalent. First, more learnable languages and concepts can nonetheless be less likely to be produced spontaneously as a result of transmission failures. We simulated cultural transmission in the laboratory to show that this can occur for memory of distinctive items: these items are more likely to be remembered, but not generated spontaneously once they have been forgotten. Second, when there are many languages or concepts that lack the more learnable property, sheer numbers can swamp the benefit produced by greater learnability. We demonstrate this using a second series of experiments involving artificial language learning. Both of these counter-examples show that simply finding a learnability bias experimentally is not sufficient to explain why a particular property is prevalent in the languages or concepts used in human societies: explanations for cultural universals based on cultural transmission need to consider the full set of hypotheses a learner could entertain and all of

  14. Statistical estimation of resin composite polymerization sufficiency using microhardness.

    PubMed

    Cohen, Mark E; Leonard, Daniel L; Charlton, David G; Roberts, Howard W; Ragain, James C

    2004-02-01

    With respect to determining sub-surface resin polymerization sufficiency, this study compared a traditional method of applying linear regression to bottom- to top-surface Knoop hardness ratios to an alternative method based on nonlinear regression. Inverse linear regression on ratios was used to estimate the exposure duration required for 80% bottom-surface hardness with respect to the top, in six light-by-material groups. Alternatively, a one-phase, two-parameter, exponential association of the form Y=Y(max)(1-e(-kt)) (where Y(max) is maximum hardness, k is a rate constant, and t is exposure duration), was used to model hardness. Inverse nonlinear regression estimated, for each condition, the exposure duration required for the bottom surface to achieve 80% of corresponding condition (light and material) top-surface Y(max). Mathematically, analysis of ratios was demonstrated to yield potentially less precise and biased estimates. Nonlinear regression yielded better statistical fit and provided easily accessible tests for differences in k across light-system groups. Another recently proposed nonlinear model for polymerization, Y=Y(max)kt(n)/(1+kt(n)), was also considered. While this new model has substantially greater phenomenological and mechanistic justification, we found that the model-fitting process was more sensitive to initial parameter values and sometimes yielded untenable results when applied to our data. However, we believe that these problems would not occur if sample points are well distributed across a wide range of exposure durations, and that the model, Y=Y(max)kt(n)/(1+kt(n)), should be considered for such data sets.

  15. Working memory maintenance is sufficient to reduce state anxiety.

    PubMed

    Balderston, Nicholas L; Quispe-Escudero, David; Hale, Elizabeth; Davis, Andrew; O'Connell, Katherine; Ernst, Monique; Grillon, Christian

    2016-11-01

    According to the attentional control theory (ACT) proposed by Eysenck and colleagues, anxiety interferes with cognitive processing by prioritizing bottom-up attentional processes over top-down attentional processes, leading to competition for access to limited resources in working memory, particularly the central executive (Eysenck, Derakshan, Santos, & Calvo, ). However, previous research using the n-back working memory task suggests that working memory load also reduces state anxiety. Assuming that similar mechanisms underlie the effect of anxiety on cognition, and the effect of cognition on anxiety, one possible implication of the ACT would suggest that the reduction of state anxiety with increasing working memory load is driven by activation of central executive attentional control processes. We tested this hypothesis using the Sternberg working memory paradigm, where maintenance processes can be isolated from central executive processes (Altamura et al., ; Sternberg, ). Consistent with the n-back results, subjects showed decreased state anxiety during the maintenance period of high-load trials relative to low-load trials, suggesting that maintenance processes alone are sufficient to achieve this state anxiety reduction. Given that the Sternberg task does not require central executive engagement, these results are not consistent with an implication of the ACT where the cognition/anxiety relationship and anxiety/cognition relationship are mediated by similar central executive mechanisms. Instead, we propose an extension of the ACT such that engaging working memory maintenance suppresses state anxiety in a load-dependent manner. Furthermore, we hypothesize that the efficacy of this effect may moderate the effect of trait anxiety on cognition.

  16. Non-Rigid Registration of Liver CT Images for CT-Guided Ablation of Liver Tumors

    PubMed Central

    Luu, Ha Manh; Klink, Camiel; Niessen, Wiro; Moelker, Adriaan; van Walsum, Theo

    2016-01-01

    CT-guided percutaneous ablation for liver cancer treatment is a relevant technique for patients not eligible for surgery and with tumors that are inconspicuous on US imaging. The lack of real-time imaging and the use of a limited amount of CT contrast agent make targeting the tumor with the needle challenging. In this study, we evaluate a registration framework that allows the integration of diagnostic pre-operative contrast enhanced CT images and intra-operative non-contrast enhanced CT images to improve image guidance in the intervention. The liver and tumor are segmented in the pre-operative contrast enhanced CT images. Next, the contrast enhanced image is registered to the intra-operative CT images in a two-stage approach. First, the contrast-enhanced diagnostic image is non-rigidly registered to a non-contrast enhanced image that is conventionally acquired at the start of the intervention. In case the initial registration is not sufficiently accurate, a refinement step is applied using non-rigid registration method with a local rigidity term. In the second stage, the intra-operative CT-images that are used to check the needle position, which often consist of only a few slices, are registered rigidly to the intra-operative image that was acquired at the start of the intervention. Subsequently, the diagnostic image is registered to the current intra-operative image, using both transformations, this allows the visualization of the tumor region extracted from pre-operative data in the intra-operative CT images containing needle. The method is evaluated on imaging data of 19 patients at the Erasmus MC. Quantitative evaluation is performed using the Dice metric, mean surface distance of the liver border and corresponding landmarks in the diagnostic and the intra-operative images. The registration of the diagnostic CT image to the initial intra-operative CT image did not require a refinement step in 13 cases. For those cases, the resulting registration had a Dice

  17. Non-Rigid Registration of Liver CT Images for CT-Guided Ablation of Liver Tumors.

    PubMed

    Luu, Ha Manh; Klink, Camiel; Niessen, Wiro; Moelker, Adriaan; Walsum, Theo van

    2016-01-01

    CT-guided percutaneous ablation for liver cancer treatment is a relevant technique for patients not eligible for surgery and with tumors that are inconspicuous on US imaging. The lack of real-time imaging and the use of a limited amount of CT contrast agent make targeting the tumor with the needle challenging. In this study, we evaluate a registration framework that allows the integration of diagnostic pre-operative contrast enhanced CT images and intra-operative non-contrast enhanced CT images to improve image guidance in the intervention. The liver and tumor are segmented in the pre-operative contrast enhanced CT images. Next, the contrast enhanced image is registered to the intra-operative CT images in a two-stage approach. First, the contrast-enhanced diagnostic image is non-rigidly registered to a non-contrast enhanced image that is conventionally acquired at the start of the intervention. In case the initial registration is not sufficiently accurate, a refinement step is applied using non-rigid registration method with a local rigidity term. In the second stage, the intra-operative CT-images that are used to check the needle position, which often consist of only a few slices, are registered rigidly to the intra-operative image that was acquired at the start of the intervention. Subsequently, the diagnostic image is registered to the current intra-operative image, using both transformations, this allows the visualization of the tumor region extracted from pre-operative data in the intra-operative CT images containing needle. The method is evaluated on imaging data of 19 patients at the Erasmus MC. Quantitative evaluation is performed using the Dice metric, mean surface distance of the liver border and corresponding landmarks in the diagnostic and the intra-operative images. The registration of the diagnostic CT image to the initial intra-operative CT image did not require a refinement step in 13 cases. For those cases, the resulting registration had a Dice

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

    PubMed

    Gerbal, Fabien; Wang, Yuan

    2017-03-07

    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 ([Formula: see text]) 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 [Formula: see text] up to 0.5 km. We obtained these measurements on recently designed superparamagnetic [Formula: see text]40-[Formula: see text]m-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 [Formula: see text] from 5.1 m to 129 m, corresponding to a bending modulus ranging from 2.2 to 54 (×[Formula: see text] 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.

  19. Impulse Representation of Sound Field due to a Rigid Wedge

    NASA Astrophysics Data System (ADS)

    Lawu, Tjundewo; Ueda, Mitsuhiro

    2004-05-01

    An impulse representation for calculating a diffraction wave due to a rigid wedge is described. The method is an approximation of the Biot-Tolstoy rigorous closed-form solution for the diffraction of point source radiation by an infinite rigid wedge. The band-limited time-domain function can be reconstructed to the original waveform if it satisfies the sampling theorem, which assumes that sampling takes place at the lowest permissible sampling rate. Therefore, if the energy is concentrated between the first sampling intervals immediately after the rise time of the time-domain function, the rigorous solution can be approximated as a delta function. This paper shows the description methods of the diffraction field near the ridge in three-dimensional space. Using the proposed impulse representation, numerical simulation was performed and the calculation accuracy was examined.

  20. Rigid amorphous fraction of Nylon 11 determined from TMDSC

    NASA Astrophysics Data System (ADS)

    Mao, Bin; Cebe, Peggy

    2012-02-01

    High precision, high accuracy heat capacity measurements were used to study both neat Nylon 11 and Nylon 11 nanocomposites which had been prepared by different processing procedures. The heat capacity step at the glass transition temperature was characterized from the reversing flow using temperature modulated differential scanning calorimetry, and this allows us to determine the mobile amorphous fraction. Heat fusion was obtained from endotherm area of the total heat flow curve, and was correlated with the degree of crystallinity determined from X-ray diffraction. Based on three phase model of the semicrystalline polymer structure, the rigid amorphous fraction (RAF) in Nylon 11 could be calculated. Studied Nylon 11 samples include solution cast, liquid quenched, and isothermally crystallized films, solution cast films containing multi-walled carbon nanotubes, and electrospun fibers. We observed that a rigid amorphous fraction exists in all Nylon 11 samples, and the amount of RAF is strongly dependent upon the crystalline fraction and the nanofiller content.

  1. Outcomes following single bubble collapse in a rigid tube

    NASA Astrophysics Data System (ADS)

    Ji, C.; Li, B.; Lin, F. Y.; Zou, J.

    2015-12-01

    Following the collapse of a vapour bubble inside a rigid tube, various outcomes could be caused by the propagation and reflection of the shock wave. Using high-speed camera system and hydrophone, the secondary cavitation and acoustic pressure curve due to the collapse of single bubble in a rigid tube are studied experimentally. The secondary cavitation has a decisive effect on the pressure pulse sequence, which usually appears at a certain area symmetric to the first bubble. Two particular cases of first bubble generated near the midpoint and the endings of the tube are also investigated, where the strength, position and period of the secondary cavitation show different features. The mechanism behind these results are discussed briefly, which is related to the propagation and reflection of the shock wave.

  2. One-DOF Superimposed Rigid Origami with Multiple States

    PubMed Central

    Liu, Xiang; Gattas, Joseph M.; Chen, Yan

    2016-01-01

    Origami-inspired engineering design is increasingly used in the development of self-folding structures. The majority of existing self-folding structures either use a bespoke crease pattern to form a single structure, or a universal crease pattern capable of forming numerous structures with multiple folding steps. This paper presents a new approach whereby multiple distinct, rigid-foldable crease patterns are superimposed in the same sheet such that kinematic independence and 1-DOF mobility of each individual pattern is preserved. This is enabled by the cross-crease vertex, a special configuration consisting of two pairs of collinear crease lines, which is proven here by means of a kinematic analysis to contain two independent 1-DOF rigid-foldable states. This enables many new origami-inspired engineering design possibilities, with two explored in depth: the compact folding of non-flat-foldable structures and sequent folding origami that can transform between multiple states without unfolding. PMID:27830732

  3. Relativistic Double Group Spinor Representations of Non-rigid Molecules

    SciTech Connect

    Balasubramanian, K

    2003-12-22

    The character theory of relativistic double group spinor representations is developed in order to represent the total rovibronic states of non-rigid molecules. It is shown that the double groups can be represented in terms of wreath products and powerful matrix cycle type generators that are used to construct their character tables. It is shown that these tables are of use when spin-orbit coupling is included in the hamiltonian even for molecules containing lighter atoms. Applications to non-rigid molecules such as Tl{sub 2}H{sub 4} /Tl{sub 2}H{sub 4}{sup +} are considered. It is shown that the tunneling splittings and the nuclear spin statistical weights can be obtained for such species using the character tables thus constructed. The spinor double groups of several other molecules such as hexamethyl dilead and heavy weakly bound clusters such as (PoH{sub 2}){sub 4} are also considered.

  4. Angled rigid neuroendoscope for continuous intraoperative visual monitoring: technical note.

    PubMed

    Tamaki, N; Hara, Y; Takaishi, Y; Shimada, S

    2001-03-01

    We developed and tested a new, angled rigid endoscope as a tool for performing continuous visual monitoring during microsurgery. The shaft of the scope is angled 110 degrees at its midportion using a prism. We used the scope continuously in 30 cases including 15 pituitary tumours, 7 brain tumours, 7 cerebral aneurysms, and one hemifacial spasm. For pituitary tumours the tip of the scope was positioned in the sphenoid sinus or in the cavity formed by tumour removal; for cerebral aneurysms it was placed behind the parent artery or the aneurysmal neck. Image quality was acceptable for intraoperative monitoring. In no case did the neuroendoscope have a deleterious impact on th e proper function of the microscope or surgical instruments. This angled rigid scope was more effective for intraoperative monitoring than conventional straight scopes. Copyright 2001 Harcourt Publishers Ltd.

  5. One-DOF Superimposed Rigid Origami with Multiple States

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; Gattas, Joseph M.; Chen, Yan

    2016-11-01

    Origami-inspired engineering design is increasingly used in the development of self-folding structures. The majority of existing self-folding structures either use a bespoke crease pattern to form a single structure, or a universal crease pattern capable of forming numerous structures with multiple folding steps. This paper presents a new approach whereby multiple distinct, rigid-foldable crease patterns are superimposed in the same sheet such that kinematic independence and 1-DOF mobility of each individual pattern is preserved. This is enabled by the cross-crease vertex, a special configuration consisting of two pairs of collinear crease lines, which is proven here by means of a kinematic analysis to contain two independent 1-DOF rigid-foldable states. This enables many new origami-inspired engineering design possibilities, with two explored in depth: the compact folding of non-flat-foldable structures and sequent folding origami that can transform between multiple states without unfolding.

  6. One-DOF Superimposed Rigid Origami with Multiple States.

    PubMed

    Liu, Xiang; Gattas, Joseph M; Chen, Yan

    2016-11-10

    Origami-inspired engineering design is increasingly used in the development of self-folding structures. The majority of existing self-folding structures either use a bespoke crease pattern to form a single structure, or a universal crease pattern capable of forming numerous structures with multiple folding steps. This paper presents a new approach whereby multiple distinct, rigid-foldable crease patterns are superimposed in the same sheet such that kinematic independence and 1-DOF mobility of each individual pattern is preserved. This is enabled by the cross-crease vertex, a special configuration consisting of two pairs of collinear crease lines, which is proven here by means of a kinematic analysis to contain two independent 1-DOF rigid-foldable states. This enables many new origami-inspired engineering design possibilities, with two explored in depth: the compact folding of non-flat-foldable structures and sequent folding origami that can transform between multiple states without unfolding.

  7. Jet Ventilation during Rigid Bronchoscopy in Adults: A Focused Review.

    PubMed

    Putz, Laurie; Mayné, Alain; Dincq, Anne-Sophie

    2016-01-01

    The indications for rigid bronchoscopy for interventional pulmonology have increased and include stent placements and transbronchial cryobiopsy procedures. The shared airway between anesthesiologist and pulmonologist and the open airway system, requiring specific ventilation techniques such as jet ventilation, need a good understanding of the procedure to reduce potentially harmful complications. Appropriate adjustment of the ventilator settings including pause pressure and peak inspiratory pressure reduces the risk of barotrauma. High frequency jet ventilation allows adequate oxygenation and carbon dioxide removal even in cases of tracheal stenosis up to frequencies of around 150 min(-1); however, in an in vivo animal model, high frequency jet ventilation along with normal frequency jet ventilation (superimposed high frequency jet ventilation) has been shown to improve oxygenation by increasing lung volume and carbon dioxide removal by increasing tidal volume across a large spectrum of frequencies without increasing barotrauma. General anesthesia with a continuous, intravenous, short-acting agent is safe and effective during rigid bronchoscopy procedures.

  8. Giant papillary conjunctivitis associated with rigid gas permeable contact lenses.

    PubMed

    Douglas, J P; Lowder, C Y; Lazorik, R; Meisler, D M

    1988-01-01

    Giant papillary conjunctivitis (GPC) is an external ocular inflammatory disorder associated with contact lens wear. GPC seems to occur less frequently with hard than with soft contact lens wear. The management of soft contact lens related GPC has included refitting with hard lenses, specifically the newer rigid gas permeable (RGP) lenses. We retrospectively studied 14 RGP lens wearers in whom GPC developed. Three patients had had GPC associated with soft contact lens wear and had been fitted with RGP lenses in an effort to restore contact lens tolerance. The interval of time between the initiation of RGP lens wear and the onset of GPC was inversely related to the lens oxygen transmissibility (DK value). Ophthalmologists should be aware of the association between GPC and rigid gas permeable lens wear.

  9. Microfluidic synthesis of rigid nanovesicles for hydrophilic reagents delivery.

    PubMed

    Zhang, Lu; Feng, Qiang; Wang, Jiuling; Sun, Jiashu; Shi, Xinghua; Jiang, Xingyu

    2015-03-23

    We present a hollow-structured rigid nanovesicle (RNV) fabricated by a multi-stage microfluidic chip in one step, to effectively entrap various hydrophilic reagents inside, without complicated synthesis, extensive use of emulsifiers and stabilizers, and laborious purification procedures. The RNV contains a hollow water core, a rigid poly (lactic-co-glycolic acid) (PLGA) shell, and an outermost lipid layer. The formation mechanism of the RNV is investigated by dissipative particle dynamics (DPD) simulations. The entrapment efficiency of hydrophilic reagents such as calcein, rhodamine B and siRNA inside the hollow water core of RNV is ≈90 %. In comparison with the combination of free Dox and siRNA, RNV that co-encapsulate siRNA and doxorubicin (Dox) reveals a significantly enhanced anti-tumor effect for a multi-drug resistant tumor model.

  10. Rotating and rolling rigid bodies and the "hairy ball" theorem

    NASA Astrophysics Data System (ADS)

    Bormashenko, Edward; Kazachkov, Alexander

    2017-06-01

    Rotating and rolling rigid bodies exemplify a fascinating theorem of topology, jokingly called the "hairy ball" theorem, which demands that any continuous tangent vector field on the sphere has at least one point where the field is zero. We demonstrate via a gedanken experiment how drilling through a rotating ball, thereby converting it into a torus, leads to the elimination of zero-velocity points on the ball surface. Using the same reasoning, zero-velocity points can be removed from the surface of a drilled spinning top. We discuss the location of zero-velocity points on the surfaces of rigid bodies rolling with no slip and with slip. Observations made from different reference frames identify various zero-velocity points. Illustrative experiments visualizing zero-velocity points are presented.

  11. The ‘twin paradox’ in relativistic rigid motion

    NASA Astrophysics Data System (ADS)

    Ben-Ya'acov, Uri

    2016-09-01

    Relativistic rigid motion suggests a new version for the so-called ‘twin paradox’, comparing the ages of two astronauts on a very long spaceship. Although there is always an instantaneous inertial frame in which the whole spaceship, being rigid, is simultaneously at rest, the twins’ ages, measured as the proper-times along their individual world lines, are different when they are located at remote parts of the spaceship. The age, or proper-time, difference depends on the distance at rest between the astronauts and the rapidity difference between start to end. The relation of the age difference with the relative Doppler shift of light signals transmitted between the astronauts and implications for the possibility to assign a common age (proper-time) to complex, spatially extended, relativistic systems are also discussed.

  12. Properties of rigid films made of PVC nanocomposites

    NASA Astrophysics Data System (ADS)

    Obloj-Muzaj, Maria; Abramowicz, Agnieszka; Kumosinski, Marcin; Zielecka, Maria; Kozakiewicz, Janusz; Gorska, Agnieszka

    2016-05-01

    PVC nanocomposites containing 0.5 wt. %/VCM of either nanosilica or hybrid core/shell type nanofiller were produced in-situ in suspension polymerisation and rigid films were prepared. The composites obtained were applied in the blends for rigid films. The properties of them were checked and showed advantageous differences in tear resistance and tensile impact properties. It appeared the composites properties let reduce the amount of impact modifiers in the blends at least 40 %. The PVC/SiO2 composite shows the best properties. Even for the blend containing 0.7 part of standard amount of impact modifier (suitable for this formulation) all the properties (except tensile impact strength crosswise) are significantly better than those of PVC blend with full amount of impact modifier.

  13. Parkinsonian Rigidity Depends on the Velocity of Passive Joint Movement

    PubMed Central

    Endo, Takuyuki; Yoshikawa, Naoya; Fujimura, Harutoshi; Sakoda, Saburo

    2015-01-01

    Background. It has been long believed that Parkinsonian rigidity is not velocity-dependent based on the neurological examination. However, this has not been verified scientifically. Methods. The elbow joints of 20 Parkinson's disease patients were passively flexed and extended, and two characteristic values, the elastic coefficient (elasticity) and the difference in bias (difference in torque measurements for extension and flexion), were identified from a plot of the angle and torque characteristics. Flexion and extension were done at two different velocities, 60°/s and 120°/s, and a statistical analysis was performed to determine whether the changes in these characteristic values were velocity-dependent. Results. The elastic coefficient was not velocity-dependent, but the difference in bias increased in a velocity-dependent manner (P = 0.0017). Conclusions. The features of rigidity may differ from the conventional definition, which states that they are not dependent on the velocity of joint movement. PMID:26788403

  14. 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.

  15. Tunable Thermoresponsiveness of Resilin via Coassembly with Rigid Biopolymers.

    PubMed

    Whittaker, Jasmin L; Dutta, Naba K; Knott, Robert; McPhee, Gordon; Voelcker, Nicolas H; Elvin, Chris; Hill, Anita; Choudhury, Namita Roy

    2015-08-18

    The ability to tune the thermoresponsiveness of recombinant resilin protein, Rec1-resilin, through a facile coassembly system was investigated in this study. The effects of change in conformation and morphology with time and the responsive behavior of Rec1-resilin in solution were studied in response to the addition of a rigid model polypeptide (poly-l-proline) or a hydrophobic rigid protein (Bombyx mori silk fibroin). It was observed that by inducing more ordered conformations and increasing the hydrophobicity the lower critical solution temperature (LCST) of the system was tuned to lower values. Time and temperature were found to be critical parameters in controlling the coassembly behavior of Rec1-resilin in both the model polypeptide and more complex protein systems. Such unique properties are useful for a wide range of applications, including drug delivery and soft tissue engineering applications.

  16. The isotopic composition of helium at high rigidities

    NASA Technical Reports Server (NTRS)

    Jordan, S. P.; Meyer, P.

    1983-01-01

    The isotopic abundance distribution of the cosmic radiation at energies beyond 1 GeV/AMU can at the present time be determined only with the geomagnetic method. A balloon-borne instrument was flown for 12 hours near the geomagnetic equator to measure the relative abundance of the helium isotopes He-3 and He-4 around 12 GV rigidity. The sharp rigidity cut-off at equatorial latitudes permitted separation of the two isotopes using a high-resolution-gas Cerenkov counter. The experiment thus confirms the predicted sharp cut-off at those latitudes and demonstrates the potential for isotopic separation of other elements, once flights of longer duration can be made.

  17. A density-independent rigidity transition in biological tissues

    NASA Astrophysics Data System (ADS)

    Bi, Dapeng; Lopez, J. H.; Schwarz, J. M.; Manning, M. Lisa

    2015-12-01

    Cell migration is important in many biological processes, including embryonic development, cancer metastasis and wound healing. In these tissues, a cell’s motion is often strongly constrained by its neighbours, leading to glassy dynamics. Although self-propelled particle models exhibit a density-driven glass transition, this does not explain liquid-to-solid transitions in confluent tissues, where there are no gaps between cells and therefore the density is constant. Here we demonstrate the existence of a new type of rigidity transition that occurs in the well-studied vertex model for confluent tissue monolayers at constant density. We find that the onset of rigidity is governed by a model parameter that encodes single-cell properties such as cell-cell adhesion and cortical tension, providing an explanation for liquid-to-solid transitions in confluent tissues and making testable predictions about how these transitions differ from those in particulate matter.

  18. Adrenal insufficiency presenting as bilateral rigid auricles: a case report

    PubMed Central

    2014-01-01

    Introduction Stiff ears appear to be a warning sign for adrenal insufficiency. This remarkable and rare sign has not been described to present in adrenal insufficiency in the setting of critical care. Case presentation We present the case of a 68-year-old Caucasian male who underwent a thymoma resection and suffered from preoperative weight loss and lack of strength. The perioperative phase was characterised by hypotension and sputum stasis due to muscle weakness, which caused two readmissions to the intensive care unit. His physical examination showed two fully rigid auricles. In retrospect, our patient suffered from secondary adrenal insufficiency and hypogonadism. Conclusions The bilateral rigid auricles appeared to be a warning sign for adrenal insufficiency. This remarkable sign is easily checked, and should prompt a higher index of suspicion towards adrenal insufficiency and other hormonal deficiencies. PMID:25209544

  19. 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.

  20. CONDORR--CONstrained Dynamics of Rigid Residues: a molecular dynamics program for constrained molecules.

    PubMed

    York, William S; Yi, Xiaobing

    2004-08-01

    A computer program CONDORR (CONstrained Dynamics of Rigid Residues) was developed for molecular dynamics simulations of large and/or constrained molecular systems, particularly carbohydrates. CONDORR efficiently calculates molecular trajectories on the basis of 2D or 3D potential energy maps, and can generate such maps based on a simple force field. The simulations involve three translational and three rotational degrees of freedom for each rigid, asymmetrical residue in the model. Total energy and angular momentum are conserved when no stochastic or external forces are applied to the model, if the time step is kept sufficiently short. Application of Langevin dynamics allows longer time steps, providing efficient exploration of conformational space. The utility of CONDORR was demonstrated by application to a constrained polysaccharide model and to the calculation of residual dipolar couplings for a disaccharide. [Figure: see text]. Molecular models (bottom) are created by cloning rigid residue archetypes (top) and joining them together. As defined here, the archetypes AX, HM and BG respectively correspond to an alpha-D-Xyl p residue, a hydroxymethyl group, and a beta-D-Glc p residue lacking O6, H6a and H6b. Each archetype contains atoms (indicated by boxes) that can be shared with other archetypes to form a linked structure. For example, the glycosidic link between the two D-Glc p residues is established by specifying that O1 of the nonreducing beta-D-Glc p (BG) residue (2) is identical to O4 of the reducing Glc p (BG) residue (1). The coordinates of the two residues are adjusted so as to superimpose these two (nominally distinct) atoms. Flexible hydroxymethyl (HM) groups (3 and 4) are treated as separate residues, and the torsional angles (normally indicated by the symbol omega) that define their geometric relationships to the pyranosyl rings of the BG residues are specified as psi3 and psi4, respectively. The torsional angles phi3 and phi4, defined solely to

  1. Cellular contractility changes are sufficient to drive epithelial scattering.

    PubMed

    Hoj, Jacob P; Davis, John A; Fullmer, Kendra E; Morrell, David J; Saguibo, Nicholas E; Schuler, Jeffrey T; Tuttle, Kevin J; Hansen, Marc D H

    2014-08-15

    inhibition of cell scattering following HGF treatment. Interestingly, restoration of myosin-based contractility in blebbistatin-treated cells results in cell scattering, including global actin rearrangements. Scattering is reminiscent of HGF-induced epithelial scattering without a concomitant increase in cell migration or decrease in adhesion strength. This scattering is dependent on RhoA, as blebbistatin-induced scattering is reduced in cells expressing dominant-negative RhoA mutants. This suggests that induction of myosin-based cellular contractility may be sufficient for cell-cell detachment during epithelial scattering.

  2. [Food self-sufficiency and the population problem in Rwanda].

    PubMed

    Tallon, F

    1988-12-01

    Food self-sufficiency is a central element of Rwanda's development policy and planning. The goal of providing each individual with at least 2100 calories per day will require increased agricultural productivity and more moderate population growth. The actions required to achieve a better balance between food production and population growth will be very difficult to achieve in Rwanda. In the past, famines resulting from war, rainfall irregularities, or other natural disasters regularly decimated the population. The last famine, in 1943-44, may have killed 1 million inhabitants of Rwanda-Urundi. Between 1966-83, the population grew from 3.3 to 5.9 million, an increase of 78%, while food production increased from 2.3 to 4.7 million tons, or 104%. The increase was due to a doubling of cultivated land, from 308,000 to 615,000 hectares, achieved by utilizing marginal lands, pastures, and forests, and by shortening fallow periods. By 1983, under pressure of population growth, the average family plot had fallen to .88 hectare. The current nutritional status of the population is in precarious balance, with adequate calorie production overall, but women and children suffer endemic malnutrition in some population sectors, leaving them vulnerable to disease and death. If population increases as projected to over 10 million in the year 2000, the average family plot may decline to scarcely 1/2 hectare. Innovations such as improved seed selection, more productive crops, use of fertilizers, and crop rotation will be required to avoid drastic declines in productivity due to soil exhaustion and erosion. Rwanda's annual population growth rate of 3.7% is the 2nd highest in the world. Fertility reduction will clearly be necessary but difficult to achieve because of the pronatalist attitudes of the population and widespread inability to envision a different future. The 1983 fertility survey indicated that 31% of married women wanted to use contraception, but despite availability of

  3. Direct inversion of rigid-body rotational dynamics

    NASA Technical Reports Server (NTRS)

    Bach, Ralph; Paielli, Russell

    1990-01-01

    The global linearization (inversion) of rigid-body rotational dynamics is reviewed, and representations in terms of quaternions and direction cosines are compared. Certain properties common to quaternions and direction cosines that make their use preferable to Euler angles and that simplify the inversion procedure are described. Applications of the inversion procedure for state estimation and attitude control are discussed. To avoid complexities caused by aerodynamics, an example of direct inversion for linear feedback control of spacecraft attitude is given.

  4. Two-beam interferometer for fourier spectroscopy with rigid pendulum

    SciTech Connect

    Burkert, P.

    1983-05-17

    A two-beam interferometer for fourier spectroscopy includes a rigid pendulum structure mounting at least one of the movable retroreflectors in a fully compensated optical system immune to tilt and lateral movement distortions. The swing of the rotatably journaled pendulum accurately confines the retroreflector(s) to movement in a single plane during scanning and, due to the low heat generated in the pendulum bearings, the simple and compact structure is well adapted to be housed in a cryostat aboard a spacecraft.

  5. Magnetron sputtering in rigid optical solar reflectors production

    NASA Astrophysics Data System (ADS)

    Asainov, O. Kh; Bainov, D. D.; Krivobokov, V. P.; Sidelev, D. V.

    2016-07-01

    Magnetron sputtering was applied to meet the growing need for glass optical solar reflectors. This plasma method provided more uniform deposition of the silver based coating on glass substrates resulted in decrease of defective reflectors fraction down to 5%. For instance, such parameter of resistive evaporation was of 30%. Silver film adhesion to glass substrate was enhanced with indium tin oxide sublayer. Sunlight absorption coefficient of these rigid reflectors was 0.081-0.083.

  6. Stability characterizations of fixtured rigid bodies with Coulomb friction

    SciTech Connect

    PANG,J.S.; TRINKLE,JEFFREY C.

    2000-02-15

    This paper formally introduces several stability characterizations of fixtured three-dimensional rigid bodies initially at rest and in unilateral contact with Coulomb friction. These characterizations, weak stability and strong stability, arise naturally from the dynamic model of the system, formulated as a complementarity problem. Using the tools of complementarity theory, these characterizations are studied in detail to understand their properties and to develop techniques to identify the stability classifications of general systems subjected to known external loads.

  7. Direct inversion of rigid-body rotational dynamics

    NASA Technical Reports Server (NTRS)

    Bach, Ralph; Paielli, Russell

    1990-01-01

    The global linearization (inversion) of rigid-body rotational dynamics is reviewed, and representations in terms of quaternions and direction cosines are compared. Certain properties common to quaternions and direction cosines that make their use preferable to Euler angles and that simplify the inversion procedure are described. Applications of the inversion procedure for state estimation and attitude control are discussed. To avoid complexities caused by aerodynamics, an example of direct inversion for linear feedback control of spacecraft attitude is given.

  8. Direct inversion of rigid-body rotational dynamics

    NASA Technical Reports Server (NTRS)

    Bach, Ralph; Paielli, Russell

    1990-01-01

    The global linearization (inversion) of rigid-body rotational dynamics is reviewed and representations in terms of quaternions and direction cosines are compared. Certain properties common to quaternions and direction cosines that make their use preferable to Euler angles and that simplify the inversion procedure are described. Applications of the inversion procedure for state estimation and attitude control are discussed. To avoid complexities caused by aerodynamics, an example of direct inversion for linear feedback control of spacecraft attitude is given.

  9. Potentials of Mean Force Between Rigid Solvated Polymers

    SciTech Connect

    FRINK, LAURA J.D.; SALINGER, ANDREW G.

    1999-09-29

    In this letter we discusses the first application of 3-dimensional nonlocal density functional calculations to the interactions of solvated rigid polymers. The three cases considered are cylindrical polymers, bead-chain polymers, and periodic polymers. We calculate potentials of mean force, and show that polymer surface structure plays a critical role in determining the solvation energy landscape which in turn controls routes to assembly of the macromolecules.

  10. Charging and discharging characteristics of a rigid solar array

    NASA Technical Reports Server (NTRS)

    Brady, G. F., Jr.; Vance, D. A.; Greenberg, S. A.

    1981-01-01

    Two rigid solar array panels were subjected to a simulated geosynchronous orbit substorm environment. During the charging sequence, distributions of accumulated surface charge were measured under eclipse and sunlight conditions. Discharge events were characterized with respect to voltage pulse signatures and amplitudes on the solar array bus leads. Post-exposure analysis of the solar array panels indicated that the electrical characteristics were not degraded in spite of the substantial discharge actvity. However, significant cratering and discoloration of the Tedlar dielectric were observed.

  11. Anisotropy of torsional rigidity of sheet polymer composite materials

    NASA Astrophysics Data System (ADS)

    Startsev, O. V.; Kovalenko, A. A.; Nasonov, A. D.

    1999-05-01

    Wide application of polymer composite materials (PCM) in modern technology calls for detailed evaluation of their stress-strain properties in a broad temperature range. To obtain such information, we use the dynamic mechanical analysis and with the help of a reverse torsion pendulum measure the dynamic torsional rigidity of PCM bars of rectangular cross section in the temperature range up to 600 K. It is found that the temperature dependences of the dynamic rigidity of the calculated values of dynamic shear moduli are governed by the percentage and properties of the binder and fibers, the layout of fibers, the phase interaction along interfaces, etc. The principles of dynamic mechanical spectrometry are used to substantiate and analyze the parameters of anisotropy by which the behavior of a composite can be described in the temperature range including the transition of the binder from the glassy into a highly elastic state. For this purpose, the values of dynamic rigidity are measured under low-amplitude vibrations of the PCM specimens with a fiber orientation angle from 0 to 90°. It is shown that for unidirectional composites the dependence between the dynamic rigidity and the fiber orientation angle is of extreme character. The value and position of the peak depend on the type of the binder and fibers and change with temperature. It is found that the anisotropy degree of PCM is dictated by the molecular mobility and significantly changes in the temperature range of transition of the binder and reinforcement from the glassy into a highly elastic state (in the case of SVM fibers). The possibility of evaluating the anisotropy of composites with other reinforcement schemes, in particular, of orthogonally reinforced PCMs, is shown.

  12. Non-rigid summing of gated PET via optical flow

    SciTech Connect

    Klein, G.J.; Reutter, B.W.; Huesman, R.H. |

    1996-12-31

    A method for summing together datasets from gated cardiac PET acquisitions is described. Optical flow techniques are used to accurately model non-rigid motion present during the cardiac cycle so that a one-to-one mapping is found between each voxel of two gated volumes. Using this mapping, image summing can take place, producing a composite dataset with improved statistics and reduced motion-induced blur. Results using a data from a gated cardiac study on a dog are presented.

  13. 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.

  14. 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.

  15. A Three Dimensional Non-Singular Modelling of Rigid Manipulators.

    DTIC Science & Technology

    1987-12-01

    511111 OTC FILE COPY (1) ’ NAVAL POSTGRADUATE SCHOOL 0 ’ Monterey, California IDTIC I{ IELECTE S MAR 08 8 f 0? THESIS A THREE DIMENSIONAL NON-SINGULAR...MODELLING OF RIGID MANIPULATORS by Sadrettin Altinok December 1987 Thesis Advisor D.L. Smith Approved for public release; distribution is unlimited. 88...MASTERS THESIS FROM _ TO 1987 DECEMBER iC 6 16 SUPPLEMENTARY NOTATION 17 COSA T i CODES 18 SUBJECT TERMS (Continue on reverse f necessary and identify by

  16. Theory of the rotation of the rigid earth

    NASA Technical Reports Server (NTRS)

    Kinoshita, H.

    1977-01-01

    Equations of motion for a triaxial rigid earth are derived in Andoyer variables. The reference plane is the ecliptic of date which is moving as a result of planetary perturbations. By using this noninertial system, the development of the disturbing function for the sun and moon is simplified, with an additional term appearing in the Hamiltonian which, however, contributes only to precessional motion. The nutation terms derived are compared with those of Woolard.

  17. As-Rigid-As-Possible molecular interpolation paths

    NASA Astrophysics Data System (ADS)

    Nguyen, Minh Khoa; Jaillet, Léonard; Redon, Stéphane

    2017-03-01

    This paper proposes a new method to generate interpolation paths between two given molecular conformations. It relies on the As-Rigid-As-Possible (ARAP) paradigm used in Computer Graphics to manipulate complex meshes while preserving their essential structural characteristics. The adaptation of ARAP approaches to the case of molecular systems is presented in this contribution. Experiments conducted on a large set of benchmarks show how such a strategy can efficiently compute relevant interpolation paths with large conformational rearrangements.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. A comparison of neighbor search algorithms for large rigid molecules.

    PubMed

    Artemova, Svetlana; Grudinin, Sergei; Redon, Stephane

    2011-10-01

    Fast determination of neighboring atoms is an essential step in molecular dynamics simulations or Monte Carlo computations, and there exists a variety of algorithms to efficiently compute neighbor lists. However, most of these algorithms are general, and not specifically designed for a given type of application. As a result, although their average performance is satisfactory, they might be inappropriate in some specific application domains. In this article, we study the case of detecting neighbors between large rigid molecules, which has applications in, e.g., rigid body molecular docking, Monte Carlo simulations of molecular self-assembly or diffusion, and rigid body molecular dynamics simulations. More precisely, we compare the traditional grid-based algorithm to a series of hierarchy-based algorithms that use bounding volumes to rapidly eliminate large groups of irrelevant pairs of atoms during the neighbor search. We compare the performance of these algorithms based on several parameters: the size of the molecules, the average distance between them, the cutoff distance, as well as the type of bounding volume used in the culling hierarchy (AABB, OBB, wrapped, or layered spheres). We demonstrate that for relatively large systems (> 100,000 atoms) the algorithm based on the hierarchy of wrapped spheres shows the best results and the traditional grid-based algorithm gives the worst timings. For small systems, however, the grid-based algorithm and the one based on the wrapped sphere hierarchy are beneficial. Copyright © 2011 Wiley Periodicals, Inc.

  3. Theory of rigid-plane phonon modes in layered crystals

    NASA Astrophysics Data System (ADS)

    Michel, K. H.; Verberck, B.

    2012-03-01

    The lattice dynamics of low-frequency rigid-plane modes in metallic (graphene multilayers, GML) and in insulating (hexagonal boron-nitride multilayers, BNML) layered crystals is investigated. The frequencies of shearing and compression (stretching) modes depend on the layer number N and are presented in the form of fan diagrams. The results for GML and BNML are very similar. In both cases, only the interactions (van der Waals and Coulomb) between nearest-neighbor planes are effective, while the interactions between more distant planes are screened. A comparison with recent Raman scattering results on low-frequency shear modes in GML [Tan , Nat. Mater., in press, doi:10.1038/nmat3245, (2012)] is made. Relations with the low-lying rigid-plane phonon dispersions in the bulk materials are established. Master curves, which connect the fan diagram frequencies for any given N, are derived. Static and dynamic thermal correlation functions for rigid-layer shear and compression modes are calculated. The results might be of use for the interpretation of friction force experiments on multilayer crystals.

  4. 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.

  5. Representing plants as rigid cylinders in experiments and models

    NASA Astrophysics Data System (ADS)

    Vargas-Luna, Andrés; Crosato, Alessandra; Calvani, Giulio; Uijttewaal, Wim S. J.

    2016-07-01

    Simulating the morphological adaptation of water systems often requires including the effects of plants on water and sediment dynamics. Physical and numerical models need representing vegetation in a schematic easily-quantifiable way despite the variety of sizes, shapes and flexibility of real plants. Common approaches represent plants as rigid cylinders, but the ability of these schematizations to reproduce the effects of vegetation on morphodynamic processes has never been analyzed systematically. This work focuses on the consequences of representing plants as rigid cylinders in laboratory tests and numerical simulations. New experiments show that the flow resistance decreases for increasing element Reynolds numbers for both plants and rigid cylinders. Cylinders on river banks can qualitatively reproduce vegetation effects on channel width and bank-related processes. A comparative review of numerical simulations shows that Baptist's method that sums the contribution of bed shear stress and vegetation drag, underestimates bed erosion within sparse vegetation in real rivers and overestimates the mean flow velocity in laboratory experiments. This is due to assuming uniform flow among plants and to an overestimation of the role of the submergence ratio.

  6. Angular rigidity in tetrahedral network glasses with changing composition

    NASA Astrophysics Data System (ADS)

    Bauchy, M.; Micoulaut, M.; Celino, M.; Le Roux, S.; Boero, M.; Massobrio, C.

    2011-08-01

    A set of oxide and chalcogenide tetrahedral glasses is investigated using molecular dynamics simulations. We show that the changes in the Ge composition affect mostly bending around germanium in binary Ge-Se systems, leaving Se-centered bending almost unchanged. In contrast, the corresponding Se twisting (quantified by the dihedral angle) depends on the Ge composition and is reduced when the system becomes rigid. It is also shown that angles involving the fourth neighbor around Ge is found to change when the system enters the stressed rigid phase. The same analysis reveals that unlike stoichiometric selenides such as GeSe2 and SiSe2, germania and silica display large standard deviations in the bond angle distributions. Within bond-bending constraints theory, this pattern can be interpreted as a manifestation of broken (i.e., ineffective) oxygen bond-bending constraints, whereas the silicon and germanium bending in oxides is found to be similar to the one found in flexible and intermediate Ge-Se systems. Our results establish the atomic-scale foundations of the phenomenological rigidity theory, thereby profoundly extending its significance and impact on the structural description of network glasses.

  7. 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.

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

    PubMed

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

    2000-07-01

    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.

  9. Fundamental Study of Emulsions Stabilized by Soft and Rigid Particles.

    PubMed

    Li, Zifu; Harbottle, David; Pensini, Erica; Ngai, To; Richtering, Walter; Xu, Zhenghe

    2015-06-16

    Two distinct uniform hybrid particles, with similar hydrodynamic diameters and comparable zeta potentials, were prepared by copolymerizing N-isopropylacrylamide (NIPAM) and styrene. These particles differed in their styrene to NIPAM (S/N) mass ratios of 1 and 8 and are referred to as S/N 1 and S/N 8, respectively. Particle S/N 1 exhibited a typical behavior of soft particles; that is, the particles shrank in bulk aqueous solutions when the temperature was increased. As a result, S/N 1 particles were interfacially active. In contrast, particle S/N 8 appeared to be rigid in response to temperature changes. In this case, the particles showed a negligible interfacial activity. Interfacial shear rheology tests revealed the increased rigidity of the particle-stabilized film formed at the heptane-water interface by S/N 1 than S/N 8 particles. As a result, S/N 1 particles were shown to be better emulsion stabilizers and emulsify a larger amount of heptane, as compared with S/N 8 particles. The current investigation confirmed a better performance of emulsion stabilization by soft particles (S/N 1) than by rigid particles (S/N 8), reinforcing the importance of controlling softness or deformability of particles for the purpose of stabilizing emulsions.

  10. Molecular Rigidity and Entropy-Enthalpy Compensation in DNA Hybridization

    NASA Astrophysics Data System (ADS)

    Douglas, Jack; Vargas-Lara, Fernando

    2015-03-01

    Entropy-enthalpy compensation (EEC) is a general and relatively poorly understood pattern in the energetic parameters governing both binding constants and relaxation processes in condensed matter. After defining the basic phenomenology, we focus on how polymer additives, chain confinement, chain length variation affect a well-studied molecular binding process, the hybridization of duplex DNA. Our study is based on a coarse-grained model of DNA that does treat water explicitly. We find that both crowding due to polymer additives and geometrical confinement lead to a change of the effective chain rigidity and that changes in DNA generally lead to a pattern entropy-enthalpy compensation in the DNA association similar to experimental observations. Modulation of the rigidity of binding specifies by constraints associated with chain structure or environmental conditions can greatly influence both the location and cooperativity of molecular binding transition and the relative enthalpy and entropy contributions to the free energy of binding. Entropy-enthalpy compensation arises in numerous synthetic and biological molecular binding processes and we suggest that that changes in molecular rigidity might provide a common explanation of this ubiquitous phenomenon.

  11. Optical Neuronavigation without Rigid Head Fixation During Awake Surgery.

    PubMed

    Freyschlag, Christian F; Kerschbaumer, Johannes; Eisner, Wilhelm; Pinggera, Daniel; Brawanski, Konstantin R; Petr, Ondra; Bauer, Marlies; Grams, Astrid E; Bodner, Thomas; Seiz, Marcel; Thomé, Claudius

    2017-01-01

    Optical neuronavigation without rigid pin fixation of the head may lead to inaccurate results because of the patient's movements during awake surgery. In this study, we report our results using a skull-mounted reference array for optical tracking in patients undergoing awake craniotomy for eloquent gliomas. Between March 2013 and December 2014, 18 consecutive patients (10 men, 8 women) with frontotemporal (n = 16) or frontoparietal (perirolandic; n = 2) lesions underwent awake craniotomy without rigid pin fixation. All patients had a skull-mounted reference array for optical tracking placed on the forehead. Accuracy of navigation was determined with pointer tip deviation measurements on superficial and bony anatomic structures. Good accuracy was defined as a tip deviation <2 mm. Gross total resection (>98%) was achieved in 7 patients (38%); >90% of tumor was resected in 8 patients (44%). In 3 patients, only subtotal resection or biopsy was performed secondary to stimulation results. In all patients, good accuracy of the optical neuronavigation system could be demonstrated without intraoperative peculiarities or complications. The reference array had to be repositioned because of loosening in 1 patient. Neuronavigation could be reliably applied to support stimulation-based resection. A skull-mounted reference array is a simple and safe method for optical neuronavigation tracking without rigid pin fixation of the patient's head. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Force Coefficients on Surging Rigid and Flexible Wings

    NASA Astrophysics Data System (ADS)

    Mancini, Peter; Jones, Anya; Granlund, Kenneth; Ol, Michael

    2013-11-01

    This study considers an aspect ratio 4 rigid flat plate and an aspect ratio 4.5 flexible wing, undergoing rectilinear motion in a water tunnel over several chord lengths at a Reynolds number of 20,000. Varying incidence angle, Reynolds number, and acceleration profile led to an extensive parameter study for both wings. Acceleration regions were linear with time and varied with distances of 0.25 to 6.0 chord-lengths. Measurements include lift and drag histories along with flow visualization of leading and trailing edge vortices throughout the entire motion by fluorescent dye injection illuminated by a laser sheet. A non-circulatory bump in lift coefficient at the end of the acceleration region was observed for each rigid wing case. The rigid wing also experienced a significant decrease in lift shortly after the wing reached its terminal velocity. This dip was followed by a second peak in lift around 6 chords traveled for every case, although the magnitudes differed among the acceleration profiles. Conversely, the flexible wing exhibited little to no non-circulatory peak at the end of acceleration and did not experience this dip and rise in lift. This study explores the influence of planform and chordwise flexibility on leading edge vortex formation, retention, and shedding.

  13. Non-rigid image registration with SalphaS filters.

    PubMed

    Liao, Shu; Chung, Albert C S

    2008-01-01

    In this paper, based on the SalphaS distributions, we design SalphaS filters and use the filters as a new feature extraction method for non-rigid medical image registration. In brain MR images, the energy distributions of different frequency bands often exhibit heavy-tailed behavior. Such non-Gaussian behavior is essential for non-rigid image registration but cannot be satisfactorily modeled by the conventional Gabor filters. This leads to unsatisfactory modeling of voxels located at the salient regions of the images. To this end, we propose the SalphaS filters for modeling the heavy-tailed behavior of the energy distributions of brain MR images, and show that the Gabor filter is a special case of the SalphaS filter. The maximum response orientation selection criterion is defined for each frequency band to achieve rotation invariance. In our framework, if the brain MR images are already segmented, each voxel can be automatically assigned a weighting factor based on the Fisher's separation criterion and it is shown that the registration performance can be further improved. The proposed method has been compared with the free-form-deformation based method, Demons algorithm and a method using Gabor features by conducting non-rigid image registration experiments. It is observed that the proposed method achieves the best registration accuracy among all the compared methods in both the simulated and real datasets obtained from the BrainWeb and IBSR respectively.

  14. Sequential Non-Rigid Structure from Motion Using Physical Priors.

    PubMed

    Agudo, Antonio; Moreno-Noguer, Francesc; Calvo, Begona; Montiel, Jose M Martinez

    2016-05-01

    We propose a new approach to simultaneously recover camera pose and 3D shape of non-rigid and potentially extensible surfaces from a monocular image sequence. For this purpose, we make use of the Extended Kalman Filter based Simultaneous Localization And Mapping (EKF-SLAM) formulation, a Bayesian optimization framework traditionally used in mobile robotics for estimating camera pose and reconstructing rigid scenarios. In order to extend the problem to a deformable domain we represent the object's surface mechanics by means of Navier's equations, which are solved using a Finite Element Method (FEM). With these main ingredients, we can further model the material's stretching, allowing us to go a step further than most of current techniques, typically constrained to surfaces undergoing isometric deformations. We extensively validate our approach in both real and synthetic experiments, and demonstrate its advantages with respect to competing methods. More specifically, we show that besides simultaneously retrieving camera pose and non-rigid shape, our approach is adequate for both isometric and extensible surfaces, does not require neither batch processing all the frames nor tracking points over the whole sequence and runs at several frames per second.

  15. Field-theoretic simulations of random copolymers with structural rigidity.

    PubMed

    Mao, Shifan; MacPherson, Quinn; Qin, Jian; Spakowitz, Andrew J

    2017-04-12

    Copolymers play an important role in a range of soft-materials applications and biological phenomena. Prevalent works on block copolymer phase behavior use flexible chain models and incorporate interactions using a mean-field approximation. However, when phase separation takes place on length scales comparable to a few monomers, the structural rigidity of the monomers becomes important. In addition, concentration fluctuations become significant at short length scales, rendering the mean-field approximation invalid. In this work, we use simulation to address the role of finite monomer rigidity and concentration fluctuations in microphase segregation of random copolymers. Using a field-theoretic Monte-Carlo simulation of semiflexible polymers with random chemical sequences, we generate phase diagrams for random copolymers. We find that the melt morphology of random copolymers strongly depends on chain flexibility and chemical sequence correlation. Chemically anti-correlated copolymers undergo first-order phase transitions to local lamellar structures. With increasing degree of chemical correlation, this first-order phase transition is softened, and melts form microphases with irregular shaped domains. Our simulations in the homogeneous phase exhibit agreement with the density-density correlation from mean-field theory. However, conditions near a phase transition result in deviations between simulation and mean-field theory for the density-density correlation and the critical wavemode. Chain rigidity and sequence randomness lead to frustration in the segregated phase, introducing heterogeneity in the resulting morphologies.

  16. Predicting Protein Hinge Motions and Allostery Using Rigidity Theory

    NASA Astrophysics Data System (ADS)

    Sljoka, Adnan; Bezginov, Alexandr

    2011-11-01

    Understanding how a 3D structure of a protein functions depends on predicting which regions are rigid, and which are flexible. One recent approach models molecules as a structure of fixed units (atoms with their bond angles as rigid units, bonds as hinges) plus biochemical constraints coming from the local geometry. This generates a `molecular graph' in the theory of combinatorial rigidity. The 6|V|-6 counting condition for 3-dimensional body-hinge structures (modulo molecular theorem), and a fast `pebble game' algorithm which tracks this count in the multigraph, have led to the development of the program FIRST, for rapid predictions of the flexibility of proteins. In this study we develop a novel protein hinge prediction algorithm via our extension of the pebble game algorithm (relevant regions detection algorithm). We have tested our hinge prediction algorithm on several proteins chosen from the dataset of manually annotated hinges available on the MOLMOV server. Many of our predictions are in very good agreement with this data set. Our algorithms can also predict `allosteric' interactions in proteins—where binding on one site of a molecule changes the shape or binding at a distance `active site' of the molecule. We also give some promising results which support the sliding piston-like movement of helices with respect to one another as a plausible mechanism by which GCPR receptors propagate conformational changes across membranes.

  17. 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

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

    PubMed Central

    Wang, Xiao-Bo; Yin, Yan; Miao, Yuan; Herth, Felix J.; Kang, Jian

    2016-01-01

    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. PMID:28066660

  19. 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.

  20. 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...