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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. Carbon dioxide based nephroscopy: a trick for laparoscopic pyelolithotomy.

    PubMed

    Mason, Barry Michael; Hoenig, David

    2008-12-01

    For certain selected cases, laparoscopic pyelolithotomy is a practical and effective method to manage renal stone disease. One such case is that of an ectopically located pelvic kidney with a large stone burden. Here, we describe our technique and provide what we feel is a trick to performing a key part of this procedure--flexible nephroscopy while using carbon dioxide gas to "inflate" the collecting system. PMID:19099514

  3. 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 ...

  4. 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.

  5. 21 CFR 876.5020 - External penile rigidity devices.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  6. 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...

  7. 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...

  8. Rigid particulate matter sensor

    DOEpatents

    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.

  9. Necessary, but also Sufficient?

    PubMed

    Martens, Sascha

    2016-07-01

    Cell biologists are equipped with a plethora of techniques and approaches to unravel the fascinating inner working of the cell. Among these, biochemistry has the ability to define the machinery that is both necessary and sufficient for a given process and, therefore, to define its core mechanism. PMID:27142894

  10. 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 existing…

  11. Sufficient Statistics: an Example

    NASA Technical Reports Server (NTRS)

    Quirein, J.

    1973-01-01

    The feature selection problem is considered resulting from the transformation x = Bz where B is a k by n matrix of rank k and k is or = to n. Such a transformation can be considered to reduce the dimension of each observation vector z, and in general, such a transformation results in a loss of information. In terms of the divergence, this information loss is expressed by the fact that the average divergence D sub B computed using variable x is less than or equal to the average divergence D computed using variable z. If D sub B = D, then B is said to be a sufficient statistic for the average divergence D. If B is a sufficient statistic for the average divergence, then it can be shown that the probability of misclassification computed using variable x (of dimension k is or = to n) is equal to the probability of misclassification computed using variable z. Also included is what is believed to be a new proof of the well known fact that D is or = to D sub B. Using the techniques necessary to prove the above fact, it is shown that the Brattacharyya distance as measured by variable x is less than or equal to the Brattacharyya distance as measured by variable z.

  12. 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.

  13. Rigidity of melting DNA.

    PubMed

    Pal, Tanmoy; Bhattacharjee, Somendra M

    2016-05-01

    The temperature dependence of DNA flexibility is studied in the presence of stretching and unzipping forces. Two classes of models are considered. In one case the origin of elasticity is entropic due to the polymeric correlations, and in the other the double-stranded DNA is taken to have an intrinsic rigidity for bending. In both cases single strands are completely flexible. The change in the elastic constant for the flexible case due to thermally generated bubbles is obtained exactly. For the case of intrinsic rigidity, the elastic constant is found to be proportional to the square root of the bubble number fluctuation. PMID:27300825

  14. Rigidity of melting DNA

    NASA Astrophysics Data System (ADS)

    Pal, Tanmoy; Bhattacharjee, Somendra M.

    2016-05-01

    The temperature dependence of DNA flexibility is studied in the presence of stretching and unzipping forces. Two classes of models are considered. In one case the origin of elasticity is entropic due to the polymeric correlations, and in the other the double-stranded DNA is taken to have an intrinsic rigidity for bending. In both cases single strands are completely flexible. The change in the elastic constant for the flexible case due to thermally generated bubbles is obtained exactly. For the case of intrinsic rigidity, the elastic constant is found to be proportional to the square root of the bubble number fluctuation.

  15. 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).

  16. 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.

  17. Effective rigidity of membranes

    NASA Astrophysics Data System (ADS)

    Peliti, L.

    1986-12-01

    The role of thermal fluctuations of shape (undulations) in reducing the effective rigidity of membranes is reviewed. The consequences of this effect on vesicle size distribution and on the structure of microemulsions, as well as on other physical phenomena, are sketched.

  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. 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. PMID:20674469

  20. 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.

  1. 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.

  2. Designing rigid carbon foams.

    PubMed

    Park, Sora; Kittimanapun, Kritsada; Ahn, Jeung Sun; Kwon, Young-Kyun; Tománek, David

    2010-08-25

    We use ab initio density functional calculations to study the stability, elastic properties and electronic structure of sp(2) carbon minimal surfaces with negative Gaussian curvature, called schwarzites. We focus on two systems with cubic unit cells containing 152 and 200 carbon atoms, which are metallic and very rigid. The porous schwarzite structure allows for efficient and reversible doping by electron donors and acceptors, making it a promising candidate for the next generation of alkali ion batteries. We identify schwarzite structures that act as arrays of interconnected spin quantum dots or become magnetic when doped. We introduce two interpenetrating schwarzite structures that may find their use as the ultimate super-capacitor.

  3. Generalized flexibility-rigidity index

    NASA Astrophysics Data System (ADS)

    Nguyen, Duc Duy; Xia, Kelin; Wei, Guo-Wei

    2016-06-01

    Flexibility-rigidity index (FRI) has been developed as a robust, accurate, and efficient method for macromolecular thermal fluctuation analysis and B-factor prediction. The performance of FRI depends on its formulations of rigidity index and flexibility index. In this work, we introduce alternative rigidity and flexibility formulations. The structure of the classic Gaussian surface is utilized to construct a new type of rigidity index, which leads to a new class of rigidity densities with the classic Gaussian surface as a special case. Additionally, we introduce a new type of flexibility index based on the domain indicator property of normalized rigidity density. These generalized FRI (gFRI) methods have been extensively validated by the B-factor predictions of 364 proteins. Significantly outperforming the classic Gaussian network model, gFRI is a new generation of methodologies for accurate, robust, and efficient analysis of protein flexibility and fluctuation. Finally, gFRI based molecular surface generation and flexibility visualization are demonstrated.

  4. 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.

  5. Rigid collapsible dish structure

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Rigid therapies, rigid minds: italian professionals' perspectives on autism interventions.

    PubMed

    Cascio, M Ariel

    2015-06-01

    Many therapies, interventions, and programs seek to improve outcomes and quality of life for people diagnosed with autism spectrum conditions. This paper addresses Italian professionals' perspectives on a variety of such interventions, including TEACCH, ABA, Defeat Autism Now!, and Doman-Delacato. Drawing on participant-observation and interviews collected in 2012-2013 in a northern region of Italy, it highlights the theme of "rigidity" that appears in professionals' discourses about both the characteristics of people with autism and the potential risks of adhering too strictly to any particular treatment protocol. The co-occurrence of the theme of rigidity across different domains demonstrates a way in which diagnostic characteristics become metaphors for medical practice. This paper proposes that such discursive moves may help bridge the gap between people with autism and people who work with them because a key attribute of people with autism-thinking and/or acting rigidly-is also a potential pitfall for people without autism.

  11. 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

  12. Rigidity generation by nonthermal fluctuations

    NASA Astrophysics Data System (ADS)

    Sheshka, R.; Recho, P.; Truskinovsky, L.

    2016-05-01

    Active stabilization in systems with zero or negative stiffness is an essential element of a wide variety of biological processes. We study a prototypical example of this phenomenon and show how active rigidity, interpreted as a formation of a pseudowell in the effective energy landscape, can be generated in an overdamped stochastic system. We link the transition from negative to positive rigidity with time correlations in the additive noise, and we show that subtle differences in the out-of-equilibrium driving may compromise the emergence of a pseudowell.

  13. Rigidity generation by nonthermal fluctuations.

    PubMed

    Sheshka, R; Recho, P; Truskinovsky, L

    2016-05-01

    Active stabilization in systems with zero or negative stiffness is an essential element of a wide variety of biological processes. We study a prototypical example of this phenomenon and show how active rigidity, interpreted as a formation of a pseudowell in the effective energy landscape, can be generated in an overdamped stochastic system. We link the transition from negative to positive rigidity with time correlations in the additive noise, and we show that subtle differences in the out-of-equilibrium driving may compromise the emergence of a pseudowell.

  14. [Dolphin's flukes: A mathematical model of rigid wing].

    PubMed

    Romanenko, E V; Pushkov, S G; Lopatin, V N

    2015-01-01

    New analytical method is used to estimate hydrodynamic forces produced by dolphin's flukes. A mathematical model is proposed that describes dolphin's flukes as a flat rigid rectangular wing whose pitch axis location varies, heaving and pitching amplitudes are sufficiently large, and the phase angle shift for the combined oscillations can change arbitrarily. The dolphin's flukes kinematic parameters are obtained and used to estimate hydrodynamic forces.

  15. [Dolphin's flukes: A mathematical model of rigid wing].

    PubMed

    Romanenko, E V; Pushkov, S G; Lopatin, V N

    2015-01-01

    New analytical method is used to estimate hydrodynamic forces produced by dolphin's flukes. A mathematical model is proposed that describes dolphin's flukes as a flat rigid rectangular wing whose pitch axis location varies, heaving and pitching amplitudes are sufficiently large, and the phase angle shift for the combined oscillations can change arbitrarily. The dolphin's flukes kinematic parameters are obtained and used to estimate hydrodynamic forces. PMID:26852573

  16. 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.

  17. 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.

  18. Evaluating Whole Chemical Mixtures and Sufficient Similarity

    EPA Science Inventory

    This powerpoint presentation supports apresentation describing dose-response assessment for complex chemical mixtures including deriving reference doses for mixtures evaluating sufficient similarity among chemical mixtures.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Enhanced rigid-bond restraints

    SciTech Connect

    Thorn, Andrea; Dittrich, Birger; Sheldrick, George M.

    2012-07-01

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

  4. Complications of rigid internal fixation.

    PubMed

    Campbell, Chris A; Lin, Kant Y

    2009-03-01

    Over the past 20 years, there have been many advances in the development of bone fixation systems used in the practice of craniomaxillofacial surgery. As surgical practices have evolved, the complications of each technologic advance have changed accordingly. Interfragmentary instability of interosseous wiring has been replaced by the risk of exposure, infection, and palpability of plate and screw fixation systems. The improved rigidity of plate fixation requires anatomic alignment of fracture fragments. Failure to obtain proper alignment has led to the phenomenon known as "open internal fixation" of fracture fragments without proper reduction. The size of the plates has decreased to minimize palpability and exposure. However limitations in their application have been encountered due to the physiologic forces of the muscles of mastication and bone healing. In the pediatric population, the long-standing presence of plates in the cranial vault resulted in reports of transcranial migration and growth restriction. These findings led to the development of resorbable plating systems, which are associated with self-limited plate palpability and soft tissue inflammatory reactions. Any rigid system including these produces growth restriction in varying amounts. In this discussion, we review the reported complication rates of miniplating and microplating systems as well as absorptive plating systems in elective and traumatic craniofacial surgery.

  5. 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.

  6. Redundant causation from a sufficient cause perspective.

    PubMed

    Gatto, Nicolle M; Campbell, Ulka B

    2010-01-01

    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. PMID:20678223

  7. Anesthesia for adult rigid bronchoscopy.

    PubMed

    Dincq, A S; Gourdin, M; Collard, E; Ocak, S; D'Odémont, J P; Dahlqvist, C; Lacrosse, D; Putz, L

    2014-01-01

    Rigid bronchoscopy under general anesthesia enables performing diagnostic and/or therapeutic procedures in the tracheobronchial tree. This technique is characterized by specific technical problems, insofar as the anesthesiologist and the operators share the same space, namely the airway. Several potential complications (hemorrhage inside the airway, threat to ventilation ...) may arise. These challenges render the ability to use the variable available techniques essential, as well as knowledge of the complications they could entail, and the ability to rapidly solve them. General anesthesia is usually total intravenous anesthesia, using short acting agents. Ventilation can be spontaneous, but more often insured using high-frequency jet ventilation. The hospital infrastructure and staff must have the expertise to perform this particular procedure, in order to limit the complication rate. PMID:25508517

  8. Anesthesia for adult rigid bronchoscopy.

    PubMed

    Dincq, A S; Gourdin, M; Collard, E; Ocak, S; D'Odémont, J P; Dahlqvist, C; Lacrosse, D; Putz, L

    2014-01-01

    Rigid bronchoscopy under general anesthesia enables performing diagnostic and/or therapeutic procedures in the tracheobronchial tree. This technique is characterized by specific technical problems, insofar as the anesthesiologist and the operators share the same space, namely the airway. Several potential complications (hemorrhage inside the airway, threat to ventilation ...) may arise. These challenges render the ability to use the variable available techniques essential, as well as knowledge of the complications they could entail, and the ability to rapidly solve them. General anesthesia is usually total intravenous anesthesia, using short acting agents. Ventilation can be spontaneous, but more often insured using high-frequency jet ventilation. The hospital infrastructure and staff must have the expertise to perform this particular procedure, in order to limit the complication rate. PMID:25470890

  9. Focused rigidity casts: an overview.

    PubMed

    Dagg, A R; Chockalingam, N; Branthwaite, H

    2013-02-01

    Focused rigidity casts (FRCs) are a novel treatment made from polymer semi-flexible cast material, used in the management of plantar foot ulceration to offload the site of ulceration. Current anecdotal evidence suggests that use of FRCs helps achieve quicker healing time. While FRCs were first used in the treatment of fractures, previous reports suggest that the FRC may be effective in the treatment of plantar foot ulceration. Although there is a paucity of evidence to support the use of FRCs in the treatment of foot ulceration, current evidence demonstrates a decrease in both wound healing time and plantar pressure. The aim of the paper is to examine the importance of offloading plantar ulcerations and introduce FRCs.

  10. Mooring and ground handling rigid airships

    NASA Technical Reports Server (NTRS)

    Walker, H., Jr.

    1975-01-01

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

  11. Rigidity and flexibility of biological networks.

    PubMed

    Gáspár, Merse E; Csermely, Peter

    2012-11-01

    The network approach became a widely used tool to understand the behaviour of complex systems in the last decade. We start from a short description of structural rigidity theory. A detailed account on the combinatorial rigidity analysis of protein structures, as well as local flexibility measures of proteins and their applications in explaining allostery and thermostability is given. We also briefly discuss the network aspects of cytoskeletal tensegrity. Finally, we show the importance of the balance between functional flexibility and rigidity in protein-protein interaction, metabolic, gene regulatory and neuronal networks. Our summary raises the possibility that the concepts of flexibility and rigidity can be generalized to all networks. PMID:23165349

  12. Rigidity and retention of ceramic root canal posts.

    PubMed

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

    2000-01-01

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

  13. Rigidity and retention of ceramic root canal posts.

    PubMed

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

    2000-01-01

    Ceramic root-canal posts offer potential advantages over other types with respect to aesthetics and biocompatibility. Any post must be sufficiently rigid and retentive to withstand functional forces. Ceraposts (1.2 mm coronal diameter, ceramic, tapering, smooth posts) and Paraposts (1.25 mm, stainless-steel, parallel, serrated posts) were tested for rigidity by means of a three-point bending test. To test retention in roots, ceramic posts were cemented using one of three protocols: (1) glass-ionomer cement, (2) silane coupling agent and resin cement, or (3) sandblasted post surface, silane coupling agent, and resin cement. Stainless-steel posts were cemented with resin. The tensile force required to dislodge the posts, following four weeks of storage in water, was recorded. Data were compared using Student's t-test and Mann-Whitney U analysis. Ceraposts were significantly more rigid than Paraposts (p < 0.001). Paraposts cemented with resin were significantly more strongly retained than Ceraposts following any cementation protocol (p < 0.001). Retention of the ceramic posts was significantly greater with a silane coupling agent and resin cement than with glass-ionomer cement (p < 0.001). Sandblasting the ceramic posts produced variable results and needs further investigation before it could be recommended. PMID:11203820

  14. 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.

  15. 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....

  16. 21 CFR 868.5540 - Rigid laryngoscope.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  17. 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....

  18. 21 CFR 868.5540 - Rigid laryngoscope.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  19. 21 CFR 868.5540 - Rigid laryngoscope.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  20. 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.

  1. The Rigid Orthogonal Procrustes Rotation Problem

    ERIC Educational Resources Information Center

    ten Berge, Jos M. F.

    2006-01-01

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

  2. Necessary and sufficient factors in classical conditioning.

    PubMed

    Damianopoulos, E N

    1982-01-01

    The issue of necessary and sufficient factors (pairing-contiguity vs. contingency-correlation) in classical (Pavlovian) excitatory conditioning is examined: first, in terms of definitional (logical) and manipulational requirements of "necessary" and "sufficient"; second, in terms of Boolean logic test models indicating experimental and control manipulations in tests of pairing and contingency as necessary and sufficient factors; and, third, by a selective review of reference experiments showing appropriate experimental and control manipulations of pairing and contingency indicated in the Boolean logic test models. Results of examination show pairing-contiguity as the sole necessary and sufficient factor for excitatory conditioning, while contingency-correlation is conceptualized as a modulating factor controlling minimal-maximal effects of pairing-contiguity. Reservations and diagnostic experiments are indicated to assess effects of uncontrolled conditioned stimulus--unconditioned stimulus (--CS--US) probability characteristics (e.g., p (CS--US)/p (--CS--US) in truly random (TR) schedule manipulations). Similar analysis of conditioned inhibition reveals insufficient evidence to support a choice among current alternatives.

  3. Towards an English Language "Sufficiency" Test.

    ERIC Educational Resources Information Center

    Yule, George

    1980-01-01

    While proficiency tests make a positive statement about the language ability of those who pass, it says nothing about those who don't. Since the proficiency test's questions are too general, a "sufficiency" test was developed to determine if students had "enough" English to meet the needs that motivated their study. (PJM)

  4. Sufficiency, Intimacy and the Good Life.

    ERIC Educational Resources Information Center

    Taylor, Donald L.

    Our capacity to provide food and shelter is freeing us from the constant burden of keeping the wolf away from the door. We are increasingly able to give our attention to other values. This type of sufficiency provides time and circumstances for developing intimate relationships. Intimate relationships are characterized by revelation of one's…

  5. 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.

  6. Sufficient separability criteria and linear maps

    NASA Astrophysics Data System (ADS)

    Lewenstein, Maciej; Augusiak, Remigiusz; Chruściński, Dariusz; Rana, Swapan; Samsonowicz, Jan

    2016-04-01

    We study families of positive and completely positive maps acting on a bipartite system CM⊗CN (with M ≤N ). The maps have a property that, when applied to any state (of a given entanglement class), result in a separable state or, more generally, a state of another certain entanglement class (e.g., Schmidt number ≤k ). This allows us to derive useful families of sufficient separability criteria. Explicit examples of such criteria have been constructed for arbitrary M ,N , with a special emphasis on M =2 . Our results can be viewed as generalizations of the known facts that in the sufficiently close vicinity of the completely depolarized state (the normalized identity matrix), all states are separable (belong to "weakly" entangled classes). Alternatively, some of our results can be viewed as an entanglement classification for a certain family of states, corresponding to mixtures of the completely polarized state with pure states, partial transposes, and/or local transformations thereof.

  7. ["The prize goes to self-sufficiency"].

    PubMed

    Trias, M

    1993-12-01

    The Colombian family planning organization Profamilia was recognized at the 1993 annual meeting of the Western Hemisphere Region of the International Planned Parenthood Federation (IPPF) for its efforts to achieve financial self-sufficiency. Because of the announced termination of annual assistance from the US Agency for International Development (USAID), one of Profamilia's most significant external donors, the pressure to achieve self-sufficiency has intensified. Funds will be made available to Profamilia before the termination of assistance to improve infrastructure, equipment, and training. A large quantity of contraceptives will also be provided, and a new endowment will be created by USAID from which Profamilia may use the earnings. Profamilia's strategy for achieving self-sufficiency consists of five specific tactics. Recuperation refers to a cautious but sustained increase in family planning fees. Diversification refers to the medical and surgical activities apart from family planning that Profamilia will carry out for profit. The social marketing program will be expanded and improved. The fourth tactic involves a series of unrelated mechanisms to generate income, and the fifth refers to reduction of all nonessential expenditures. The measures will be made without hurting the quality of Profamilia's services or improving the average socioeconomic profile of users, who will continue to belong primarily to the less favored classes. The continued assistance of the IPPF is especially important to Profamilia as it prepares for the change. PMID:12287890

  8. ["The prize goes to self-sufficiency"].

    PubMed

    Trias, M

    1993-12-01

    The Colombian family planning organization Profamilia was recognized at the 1993 annual meeting of the Western Hemisphere Region of the International Planned Parenthood Federation (IPPF) for its efforts to achieve financial self-sufficiency. Because of the announced termination of annual assistance from the US Agency for International Development (USAID), one of Profamilia's most significant external donors, the pressure to achieve self-sufficiency has intensified. Funds will be made available to Profamilia before the termination of assistance to improve infrastructure, equipment, and training. A large quantity of contraceptives will also be provided, and a new endowment will be created by USAID from which Profamilia may use the earnings. Profamilia's strategy for achieving self-sufficiency consists of five specific tactics. Recuperation refers to a cautious but sustained increase in family planning fees. Diversification refers to the medical and surgical activities apart from family planning that Profamilia will carry out for profit. The social marketing program will be expanded and improved. The fourth tactic involves a series of unrelated mechanisms to generate income, and the fifth refers to reduction of all nonessential expenditures. The measures will be made without hurting the quality of Profamilia's services or improving the average socioeconomic profile of users, who will continue to belong primarily to the less favored classes. The continued assistance of the IPPF is especially important to Profamilia as it prepares for the change.

  9. [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.

  10. Length-dependence of flexural rigidity as a result of anisotropic elastic properties of microtubules

    SciTech Connect

    Li, C.; Ru, C.Q. . E-mail: c.ru@ualberta.ca; Mioduchowski, A.

    2006-10-27

    Unexplained length-dependence of flexural rigidity and Young's modulus of microtubules is studied using an orthotropic elastic shell model. It is showed that vibration frequencies and buckling load predicted by the accurate orthotropic shell model are much lower than that given by the approximate isotropic beam model for shorter microtubules, although the two models give almost identical results for sufficiently long microtubules. It is this inaccuracy of the isotropic beam model used by all previous researchers that leads to reported lower flexural rigidity and Young's modulus for shorter microtubules. In particular, much lower shear modulus and circumferential Young's modulus, which only weaken flexural rigidity of shorter microtubules, are responsible for the observed length-dependence of the flexural rigidity. These results confirm that longitudinal Young's modulus of microtubules is length-independent, and the observed length-dependence of the flexural rigidity and Young's modulus is a result of strongly anisotropic elastic properties of microtubules which have a length-dependent weakening effect on flexural rigidity of shorter microtubules.

  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.

  12. Sufficient dimension reduction for longitudinally measured predictors.

    PubMed

    Pfeiffer, Ruth M; Forzani, Liliana; Bura, Efstathia

    2012-09-28

    We propose a method to combine several predictors (markers) that are measured repeatedly over time into a composite marker score without assuming a model and only requiring a mild condition on the predictor distribution. Assuming that the first and second moments of the predictors can be decomposed into a time and a marker component via a Kronecker product structure that accommodates the longitudinal nature of the predictors, we develop first-moment sufficient dimension reduction techniques to replace the original markers with linear transformations that contain sufficient information for the regression of the predictors on the outcome. These linear combinations can then be combined into a score that has better predictive performance than a score built under a general model that ignores the longitudinal structure of the data. Our methods can be applied to either continuous or categorical outcome measures. In simulations, we focus on binary outcomes and show that our method outperforms existing alternatives by using the AUC, the area under the receiver-operator characteristics (ROC) curve, as a summary measure of the discriminatory ability of a single continuous diagnostic marker for binary disease outcomes.

  13. 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

  14. Trial of a self-sufficient cottage

    SciTech Connect

    Fujii, Iwane )

    1991-01-01

    Environmental disturbances, including air pollution, are increasing all over the world. In order to investigate the possibility of reducing these disturbances, a fully self-sufficient prototype cottage was built in the countryside. The cottage is not equipped with an external electric power supply nor tap water from the main. The cottage possesses a solar cell array system linked to lead-acid batteries to supply electricity and a well with a domestic pump operated by the electricity generated. A rainwater tank provides water for nonpotable uses. Additional equipment and ideas have been implemented in the cottage to promote energy saving; these are also described in detail in this paper. Experimental results on the effect of heat storage panels used for space heating are also given.

  15. Policy Capacity Is Necessary but Not Sufficient

    PubMed Central

    Gen, Sheldon; Wright, Amy Conley

    2015-01-01

    Policy capacity focuses on the managerial and organizational abilities to inform policy decisions with sound research and analysis, and facilitate policy implementation with operational efficiency. It stems from a view of the policy process that is rational and positivistic, in which optimal policy choices can be identified, selected, and implemented with objectivity. By itself, however, policy capacity neglects the political aspects of policy-making that can dominate the process, even in health policies. These technical capabilities are certainly needed to advance reforms in health policies, but they are not sufficient. Instead, they must be complemented with public engagement and policy advocacy to ensure support from the public that policies are meant to serve. PMID:26673469

  16. 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.

  17. 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).

  18. Scratch resistance of rigid contact lens materials.

    PubMed

    Tranoudis, I; Efron, N

    1996-07-01

    Practitioners have long recognised the importance of determining the extent of scratching on the surface of rigid contact lenses when deciding on lens replacement. Despite this, little research has been undertaken to define this problem. The extent of scratching of rigid contact lens materials was evaluated and this property was related to material oxygen permeability and refractive index. One hundred and forty lenses made from 28 different rigid materials were evaluated in a masked and randomised manner. Scratches were created on the front surface of the lenses using an apparatus that was specifically designed and constructed for this experiment. The extent of scratching was quantitatively evaluated using a computer-based scanning and image analysis system. The oxygen permeability of all materials was measured using the polarographic method. An Atago N3000 hand-held refractometer was used to measure the refractive index of these materials. Three significant correlations were revealed: an inverse relationship (r = -0.813, P < 0.0001) between oxygen permeability and refractive index; a positive relationship (r = 0.511, P < 0.008) between oxygen permeability and the extent of scratching; and an inverse relationship (r = -0.539, P < 0.0058) between refractive index and the extent of scratching. The information generated in this study concerning scratch resistance of rigid contact-lens materials may assist the contact lens industry and contact lens practitioners in developing and prescribing rigid lenses with optimal performance characteristics.

  19. 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...

  20. 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...

  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...

  2. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC types are... equipment designed to withstand the whole load when IBCs are stacked, for liquids. (6) 31H2 freestanding, for liquids. (b) Rigid plastic IBCs consist of a rigid plastic body, which may have...

  3. 49 CFR 178.706 - Standards for rigid plastic IBCs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic IBC... structural equipment designed to withstand the whole load when IBCs are stacked, for liquids. (6) 31H2 freestanding, for liquids. (b) Rigid plastic IBCs consist of a rigid plastic body, which may have...

  4. The self-sufficient solar house Freiburg

    SciTech Connect

    Goetzberger, A.; Stahl, W.; Bopp, G.; Heinzel, A.; Voss, K.

    1994-12-31

    The Fraunhofer Institute for Solar Energy Systems has built a Self-Sufficient Solar House (SSSH) in Freiburg, Germany. The aim of the project is to provide the entire energy demand for heating, domestic hot water, electricity and cooking by the sun. The combination of highly efficient solar systems with conventional means to save energy is the key to the successful operation of the house. With transparent insulation of building walls utilizing winter insulation the heating demand of the building is almost zero. Small size seasonal high energy storage is accomplished by electrolysis of water and pressurized storage of hydrogen and oxygen. The energy for electricity and hydrogen generation is supplied by solar cells. Hydrogen can be reconverted to electricity with a fuel cell or used for cooking. It also serves as a back-up for low temperature heat. There are provisions for short-term storage of electricity and optimal routing of energy. The SSSH is occupied by a family. An intensive measurement program is being carried out. The data are used for the validation of the dynamic simulation calculations, which formed the basis for planning the SSSH. 28 refs., 42 figs., 9 tabs.

  5. Sufficient trial size to inform clinical practice.

    PubMed

    Manski, Charles F; Tetenov, Aleksey

    2016-09-20

    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

  6. Sufficient condition for Gaussian departure in turbulence.

    PubMed

    Tordella, Daniela; Iovieno, Michele; Bailey, Peter Roger

    2008-01-01

    The interaction of two isotropic turbulent fields of equal integral scale but different kinetic energy generates the simplest kind of inhomogeneous turbulent field. In this paper we present a numerical experiment where two time decaying isotropic fields of kinetic energies E1 and E2 initially match over a narrow region. Within this region the kinetic energy varies as a hyperbolic tangent. The following temporal evolution produces a shearless mixing. The anisotropy and intermittency of velocity and velocity derivative statistics is observed. In particular the asymptotic behavior in time and as a function of the energy ratio E_{1}E_{2}-->infinity is discussed. This limit corresponds to the maximum observable turbulent energy gradient for a given E1 and is obtained through the limit E_{2}-->0 . A field with E_{1}E_{2}-->infinity represents a mixing which could be observed near a surface subject to a very small velocity gradient separating two turbulent fields, one of which is nearly quiescent. In this condition the turbulent penetration is maximum and reaches a value equal to 1.2 times the nominal mixing layer width. The experiment shows that the presence of a turbulent energy gradient is sufficient for the appearance of intermittency and that during the mixing process the pressure transport is not negligible with respect to the turbulent velocity transport. These findings may open the way to the hypothesis that the presence of a gradient of turbulent energy is the minimal requirement for Gaussian departure in turbulence.

  7. 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.

  8. 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}.

  9. How substrate rigidity regulates the cellular motility

    NASA Astrophysics Data System (ADS)

    Sarvestani, Alireza

    2011-03-01

    Mechanical stiffness of bio-adhesive substrates has been recognized as a major regulator of cell motility. We present a simple physical model to study the crawling locomotion of a contractile cell on a soft elastic substrate. The mechanism of rigidity sensing is accounted for using Schwarz's two spring model (Schwarz et al. (2006) BioSystems 83, 225-232). The predicted dependency between the speed of motility and substrate stiffness is qualitatively consistent with experimental observations. The model demonstrates that the rigidity dependent motility of cells is rooted in the regulation of actomyosin contractile forces by substrate deformation at each anchorage point. On stiffer substrates, the traction forces required for cell translocation acquire larger magnitude but show weaker asymmetry which leads to slower cell motility. On very soft substrates, the model predicts a biphasic relationship between the substrate rigidity and the speed of locomotion, over a narrow stiffness range, which has been observed experimentally for some cell types.

  10. Refractive index of rigid contact lens materials.

    PubMed

    Tranoudis, I; Efron, N

    1998-01-01

    A simple hand-held refractometer was used to measure the refractive index of 27 rigid gas permeable contact lens materials. As a general rule, lenses with refractive indices lower than 1.458 are made from fluorosilicone acrylates; lenses with refractive indices in the range of 1.458 to 1.469 are made from either fluorosilicone acrylates or silicone acrylates; and lenses with refractive indices greater than 1.469 are made from silicone acrylates. It is demonstrated how refractometry can be used by contact lens practitioners for the identification and verification of rigid contact lenses.

  11. Rigidity analysis of HIV-1 protease

    NASA Astrophysics Data System (ADS)

    Heal, J. W.; Wells, S. A.; Jimenez-Roldan, E.; Freedman, R. F.; Römer, R. A.

    2011-03-01

    We present a rigidity analysis on a large number of X-ray crystal structures of the enzyme HIV-1 protease using the 'pebble game' algorithm of the software FIRST. We find that although the rigidity profile remains similar across a comprehensive set of high resolution structures, the profile changes significantly in the presence of an inhibitor. Our study shows that the action of the inhibitors is to restrict the flexibility of the β-hairpin flaps which allow access to the active site. The results are discussed in the context of full molecular dynamics simulations as well as data from NMR experiments.

  12. 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.

  13. Rigid polyurethane and kenaf core composite foams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  14. Rigid body dynamics on the Poisson torus

    NASA Astrophysics Data System (ADS)

    Richter, Peter H.

    2008-11-01

    The theory of rigid body motion with emphasis on the modifications introduced by a Cardan suspension is outlined. The configuration space is no longer SO(3) but a 3-torus; the equivalent of the Poisson sphere, after separation of an angular variable, is a Poisson torus. Iso-energy surfaces and their bifurcations are discussed. A universal Poincaré section method is proposed.

  15. Anaesthetic implications of rigid spine syndrome.

    PubMed

    Jorgensen, B G; Laub, M; Knudsen, R H

    1999-01-01

    The perioperative management of a 14-year-old girl, suffering from the muscular disorder rigid spine syndrome, is presented. The anaesthetic implications with regard to possible difficult intubation, cardiac involvement, malignant hyperthermia, neuromuscular blocking agents, and postoperative recovery are discussed. PMID:10411775

  16. 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)

  17. Bending rigidity of composite resin coating clasps.

    PubMed

    Ikebe, K; Kibi, M; Ono, T; Nokubi, T

    1993-12-01

    The purpose of this study is to examine the bending profiles of composite resin coating cast clasps. The cobalt-chromium alloy cast clasps were made using tapered wax pattern. Silane coupling method (Silicoater MD, Kulzer Co.) was used to attach composite resin to metal surface. The breakage and the bending rigidity of composite resin coating clasps were evaluated. Results were as follows: 1) After the repeated bending test to the tips of clasp arm at 10,000 times in 0.25 mm deflection, neither crack on composite resin surface nor separation at resin/metal interface was observed in any specimen. 2) There was no significant difference in the bending rigidity of clasp arms between before and after composite resin coating. From these results, it was demonstrated that the composite resin coating cast clasp was available in clinical cases and coating with composite resin had little influence on the bending rigidity of clasp arms. Therefore, it was suggested that our clasp designing and fabricating system to control the bending rigidity of clasp arms could be applied to composite resin coating clasps. PMID:8935086

  18. Rigid spinal muscular dystrophy and rigid spine syndrome: report of 7 children.

    PubMed

    Koul, Roshan; Al-Yarubi, Saif; Al-Kindy, Hussein; Al-Futaisi, Amna; Al-Thihli, Khalid; Chacko, Poovathoor Alexander; Sankhla, Dilip

    2014-11-01

    Seven children (5 male, 2 female) were seen over the last 16 years with rigid spine syndrome. Six children had rigid spinal muscular dystrophy (selenoprotein N1-related myopathy [SEPN1RM]) and 1 had myopathy associated with rigid spine. The main presenting complaint in all was difficulty in bending the spine. The diagnosis was made on clinical features and imaging of the paraspinal muscles. Muscle histopathology revealed minimal myopathic changes to severe muscle degeneration. Genetic testing, which was only available for the last case, for selenoprotein was negative.

  19. [Parkinsonian rigidity: clinical and physiopathologic aspects].

    PubMed

    Delwaide, P J; Pepin, J L; Maertens de Noordhout, A

    1990-01-01

    Neurophysiologic mechanisms responsible for parkinsonian rigidity are poorly understood. In any case, they have to fit all the clinical data which are first reviewed before discussing 2 theories which are proposed to interpret rigidity. The first theory postulates that increased resistance to mobilization is due to hyperactivity in a long loop reflex pathway which originates at the neuromuscular spindles and relays in the motor cortex. This theory is based on the largely accepted finding that, in parkinsonian patients, M2 response is increased when a voluntary movement is abruptly stopped. Although popular this hypothesis is far from explaining all the clinical facts, namely that rigidity is equal in extensor and flexor, proximal and distal muscles. Based on a reflex set by primary afferent discharges, it is incompatible with the lack of rigidity reinforcement after faster passive mobilization. The second theory rests on data obtained from electrophysiological studies of some spinal interneurones. Both IA and IB inhibitory interneurones are functionally modified but not in the same direction. While the IA inhibitory interneurone is facilitated, the IB inhibitory interneurone is less active. Disappearance of autogenic inhibition can explain rigidity at rest and the tonic stretch reflex. In addition, interneurones intervening in the flexor reflex disclose a modified excitability. It is possible to interpret these facts by postulating an abnormal influence transmitted through descending reticulospinal pathways. This abnormal influence would result from modified activation of reticular nuclei by afferents projecting from the basal ganglia. Such a hypothesis is open to experimental testing through the startle reaction. The latter facilitates the H reflex by the reticulospinal pathways, the influence of cortex--if any--being negligible.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. 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.

  1. Rigid Cluster Decomposition Reveals Criticality in Frictional Jamming.

    PubMed

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

    2016-01-15

    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. PMID:26824572

  2. Quasiclassical trajectory studies of rigid rotor--rigid surface scattering. II. Corrugated surface

    SciTech Connect

    Park, S.C.; Bowman, J.M.

    1984-03-01

    The quasiclassical trajectory method, previously applied to rigid rotor--rigid flat surface scattering (J. M. Bowman and S. C. Park, J. Chem. Phys. 77, 5441 (1982)) is applied to a rigid rotor--rigid corrugated surface, i.e., a N/sub 2/--LiF(001), system. The mechanisms for rotational excitation at low and high collision energies are studied as well as their dependence on initial beam orientation and corrugation strength. A significant correlation between long-lived trajectories and high rotational excitation is found for low energy collisions and rotational rainbows are clearly observed in the high energy regime, although these features are broadened relative to the flat surface reported previously.

  3. Does a rigid body limit maneuverability?

    PubMed

    Walker, J A

    2000-11-01

    Whether a rigid body limits maneuverability depends on how maneuverability is defined. By the current definition, the minimum radius of the turn, a rigid-bodied, spotted boxfish Ostracion meleagris approaches maximum maneuverability, i.e. it can spin around with minimum turning radii near zero. The radius of the minimum space required to turn is an alternative measure of maneuverability. By this definition, O. meleagris is not very maneuverable. The observed space required by O. meleagris to turn is slightly greater than its theoretical minimum but much greater than that of highly flexible fish. Agility, the rate of turning, is related to maneuverability. The median- and pectoral-fin-powered turns of O. meleagris are slow relative to the body- and caudal-fin-powered turns of more flexible fish.

  4. Sticky Particles: Modeling Rigid Aggregates in Dense Planetary Rings

    NASA Astrophysics Data System (ADS)

    Perrine, Randall P.; Richardson, D. C.; Scheeres, D. J.

    2008-09-01

    We present progress on our study of planetary ring dynamics. We use local N-body simulations to examine small patches of dense rings in which self-gravity and mutual collisions dominate the dynamics of the ring material. We use the numerical code pkdgrav to model the motions of 105-7 ring particles, using a sliding patch model with modified periodic boundary conditions. The exact nature of planetary ring particles is not well understood. If covered in a frost-like layer, such irregular surfaces may allow for weak cohesion between colliding particles. Thus we have recently added new functionality to our model, allowing "sticky particles” to lock into rigid aggregates while in a rotating reference frame. This capability allows particles to adhere to one another, forming irregularly shaped aggregates that move as rigid bodies. (The bonds between particles can subsequently break, given sufficient stress.) These aggregates have greater strength than gravitationally bound "rubble piles,” and are thus able to grow larger and survive longer under similar stresses. This new functionality allows us to explore planetary ring properties and dynamics in a new way, by self-consistently forming (and destroying) non-spherical aggregates and moonlets via cohesive forces, while in a rotating frame, subjected to planetary tides. (We are not aware of any similar implementations in other existing models.) These improvements allow us to study the many effects that particle aggregation may have on the rings, such as overall ring structure; wake formation; equilibrium properties of non-spherical particles, like pitch angle, orientation, shape, size distribution, and spin; and the surface properties of the ring material. We present test cases and the latest results from this new model. This work is supported by a NASA Earth and Space Science Fellowship.

  5. 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.

  6. Amiodarone keratopathy and rigid contact lens wear.

    PubMed

    Astin, C L

    2001-01-01

    Two cases are presented of patients wearing rigid gas permeable contact lenses who exhibited the typical fan-shaped patterns of corneal pigment deposition related to long-term medication containing amiodarone. The vortex corneal epitheliopathy and contact lens tolerance were monitored over several years. In both cases, the lens material was replaced with one incorporating an ultra-violet light inhibitor in view of the possibility of medically induced photosensitivity.

  7. 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.

  8. Rapid determination of RMSDs corresponding to macromolecular rigid body motions.

    PubMed

    Popov, Petr; Grudinin, Sergei

    2014-05-01

    Finding the root mean sum of squared deviations (RMSDs) between two coordinate vectors that correspond to the rigid body motion of a macromolecule is an important problem in structural bioinformatics, computational chemistry, and molecular modeling. Standard algorithms compute the RMSD with time proportional to the number of atoms in the molecule. Here, we present RigidRMSD, a new algorithm that determines a set of RMSDs corresponding to a set of rigid body motions of a macromolecule in constant time with respect to the number of atoms in the molecule. Our algorithm is particularly useful for rigid body modeling applications, such as rigid body docking, and also for high-throughput analysis of rigid body modeling and simulation results. We also introduce a constant-time rotation RMSD as a similarity measure for rigid molecules. A C++ implementation of our algorithm is available at http://nano-d.inrialpes.fr/software/RigidRMSD. PMID:24615729

  9. 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).

  10. Modeling the Flexural Rigidity of Rod Photoreceptors

    PubMed Central

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

    2013-01-01

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

  11. Origin of rigidity in dry granular solids.

    PubMed

    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.

  12. Permeability of Rigid Fibrous Refractory Insulations

    NASA Technical Reports Server (NTRS)

    Marschall, J.; Milos, F. S.; Rasky, Daniel J. (Technical Monitor)

    1996-01-01

    Rigid fibrous refractory insulations (TPS tiles) are integral components of many spacecraft thermal protection systems. These materials are composed of refractory fibers With diameters on the order of 1 to 15 micrometers. They are lightweight and have an open, highly porous microstructure. Typical densities are less than 500 kilograms per cubic meters, and porosities generally exceed 0.8. Because of their open porosity, these materials are permeable to gas glow. There are numerous instances in which internal gas transport in a thermal protection system could be important; examples include the penetration of hot boundary-layer gases into the insulation, the flow of decomposition (pyrolysis) products from the interior, the use of convective flows to mitigate ice formation caused by cryopumping, and the design of refractory vents for pressure equilibration during atmospheric entry. Computational analysis of gas flow through porous media requires values of permeability which have not previously been available for the rigid fibrous insulations used in thermal protection systems. This paper will document measurements of permeability for a variety of insulations from NASA's LI, FRCI, and AETB families of lightweight ceramic ablators. The directional anisotropy of permeability and its dependence on gas pressure and material density will be presented. It will be shown that rarified-flow effects are significant in the flow through such materials. Connections will be drawn between the insulation microstructure and permeability. The paper will also include representative computations of flow through rigid fibrous insulations.

  13. 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...

  14. 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... 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...

  15. 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...

  16. 30 CFR 57.11004 - Portable rigid ladders.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Portable rigid ladders. 57.11004 Section 57.11004 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Escapeways Travelways-Surface and Underground § 57.11004 Portable rigid ladders. Portable rigid ladders...

  17. 30 CFR 56.11004 - Portable rigid ladders.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Portable rigid ladders. 56.11004 Section 56.11004 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL....11004 Portable rigid ladders. Portable rigid ladders shall be provided with suitable bases and...

  18. 30 CFR 57.11004 - Portable rigid ladders.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Portable rigid ladders. 57.11004 Section 57.11004 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Escapeways Travelways-Surface and Underground § 57.11004 Portable rigid ladders. Portable rigid ladders...

  19. 30 CFR 56.11004 - Portable rigid ladders.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Portable rigid ladders. 56.11004 Section 56.11004 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL....11004 Portable rigid ladders. Portable rigid ladders shall be provided with suitable bases and...

  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, 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...

  2. 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...

  3. 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...

  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. 39 CFR 491.3 - Sufficient legal form.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... AND THE POSTAL RATE COMMISSION § 491.3 Sufficient legal form. No document purporting to garnish employee wages shall be deemed sufficient unless it can be determined from the face of the document that it... 39 Postal Service 1 2013-07-01 2013-07-01 false Sufficient legal form. 491.3 Section 491.3...

  6. 39 CFR 491.3 - Sufficient legal form.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... AND THE POSTAL RATE COMMISSION § 491.3 Sufficient legal form. No document purporting to garnish employee wages shall be deemed sufficient unless it can be determined from the face of the document that it... 39 Postal Service 1 2010-07-01 2010-07-01 false Sufficient legal form. 491.3 Section 491.3...

  7. 39 CFR 491.3 - Sufficient legal form.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... AND THE POSTAL RATE COMMISSION § 491.3 Sufficient legal form. No document purporting to garnish employee wages shall be deemed sufficient unless it can be determined from the face of the document that it... 39 Postal Service 1 2014-07-01 2014-07-01 false Sufficient legal form. 491.3 Section 491.3...

  8. 39 CFR 491.3 - Sufficient legal form.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... AND THE POSTAL RATE COMMISSION § 491.3 Sufficient legal form. No document purporting to garnish employee wages shall be deemed sufficient unless it can be determined from the face of the document that it... 39 Postal Service 1 2012-07-01 2012-07-01 false Sufficient legal form. 491.3 Section 491.3...

  9. Expandable and rigid endorectal coils for prostate MRI: impact on prostate distortion and rigid image registration.

    PubMed

    Kim, Yongbok; Hsu, I-Chow J; Pouliot, Jean; Noworolski, Susan Moyher; Vigneron, Daniel B; Kurhanewicz, John

    2005-12-01

    Endorectal coils (ERCs) are used for acquiring high spatial resolution magnetic resonance (MR) images of the human prostate. The goal of this study is to determine the impact of an expandable versus a rigid ERC on changes in the location and deformation of the prostate gland and subsequently on registering prostate images acquired with and without an ERC. Sagittal and axial T2 weighted MR images were acquired from 25 patients receiving a combined MR imaging/MR spectroscopic imaging staging exam for prostate cancer. Within the same exam, images were acquired using an external pelvic phased array coil both alone and in combination with either an expandable ERC (MedRad, Pittsburgh, PA) or a rigid ERC (USA Instruments, Aurora, OH). Rotations, translations and deformations caused by the ERC were measured and compared. The ability to register images acquired with and without the ERC using a manual rigid-body registration was assessed using a similarity index (SI). Both ERCs caused the prostate to tilt anteriorly with an average tilt of 18.5 degrees (17.4 +/- 9.9 and 19.5 +/- 11.3 degrees, mean +/- standard deviation, for expandable and rigid ERC, respectively). However, the expandable coil caused a significantly larger distortion of the prostate as compared to the rigid coil; compressing the prostate in the anterior/posterior direction by 4.1 +/- 3.0 mm vs 1.2 +/- 2.2 mm (14.5% vs 4.8%) (p < 0.0001), and widening the prostate in the right/left direction by 3.8 +/- 3.7 mm vs 1.5 +/- 3.1 mm (8.3% vs 3.4%) (p = 0.004). Additionally, the ability to manually align prostate images acquired with and without ERC was significantly (p < 0.0001) better for the rigid coil (SI = 0.941 +/- 0.008 vs 0.899 +/- 0.033, for the rigid and expandable coils, respectively). In conclusion, the manual rigid-body alignment of prostate MR images acquired with and without the ERC can be improved through the use of a rigid ERC. PMID:16475755

  10. 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.

  11. 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

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

    NASA Astrophysics Data System (ADS)

    Rangin, Claude

    2016-01-01

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

  13. 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. PMID:26472363

  14. 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.

  15. 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.

  16. 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.

  17. Rigid and flexible OLEDs: prototypes to applications

    NASA Astrophysics Data System (ADS)

    Monz, Stefan; Wolf, Konrad; Möbius, Hildegard; Blankenbach, Karlheinz

    2011-03-01

    Major achievements of this research project on rigid and flexible OLEDs are: lifetime enhancement by advanced constant luminance (L) operation, integration into textiles and furthermore, the prototype production on flexible PET/ITO substrates of polymer OLEDs. Our OLEDs were manufactured with spin-coating assisted by ink-jet printing. We introduced constant luminance operation (instead of the usual constant current) which was implemented in order to extend the overall lifetime of OLEDs. A threefold lifetime improvement was achieved by maintaining 50% luminance using an advanced microcontroller-based lifetime(LT) model. Various approaches to textile integration and evaluation of environmental issues in clothes (e.g. moisture) were investigated.

  18. Edge shape and comfort of rigid lenses.

    PubMed

    La Hood, D

    1988-08-01

    One of the main factors determining the comfort of a rigid contact lens is the shape of the edge. The comfort of four different contact lens edge shapes was assessed with four unadapted subjects in a randomized masked trial. Lenses with well rounded anterior edge profiles were found to be significantly more comfortable than lenses with square anterior edges. There was no significant difference in subjective comfort between a rounded and square posterior edge profile. The results suggest that the interaction of the edge with the eyelid is more important in determining comfort than edge effects on the cornea, when lenses are fitted according to a corneal alignment philosophy. PMID:3177585

  19. 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.

  20. 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.

  1. Hydrodynamic synchronization between objects with cyclic rigid trajectories.

    PubMed

    Uchida, Nariya; Golestanian, Ramin

    2012-12-01

    Synchronization induced by long-range hydrodynamic interactions is attracting attention as a candidate mechanism behind coordinated beating of cilia and flagella. Here we consider a minimal model of hydrodynamic synchronization in the low Reynolds number limit. The model consists of rotors, each of which assumed to be a rigid bead making a fixed trajectory under periodically varying driving force. By a linear analysis, we derive the necessary and sufficient conditions for a pair of rotors to synchronize in phase. We also derive a non-linear evolution equation for their phase difference, which is reduced to minimization of an effective potential. The effective potential is calculated for a variety of trajectory shapes and geometries (either bulk or substrated), for which the stable and metastable states of the system are identified. Finite size of the trajectory induces asymmetry of the potential, which also depends sensitively on the tilt of the trajectory. Our results show that flexibility of cilia or flagella is not a requisite for their synchronized motion, in contrast to previous expectations. We discuss the possibility to directly implement the model and verify our results by optically driven colloids. PMID:23315132

  2. A constitutive theory for rigid polyurethane foam

    SciTech Connect

    Neilsen, M.K.; Krieg, R.D.; Schreyer, H.L.

    1992-12-31

    Rigid, closed-cell, polyurethane foam consists of interconnected polyurethane plates which form cells. When this foam is compressed, it exhibits an initial elastic regime which is followed by a plateau regime in which the load required to compress the foam remains nearly constant. In the plateau regime, cell walls are damaged and large permanent volume changes are generated. As additional load is applied, cell walls are compressed against neighboring cell walls, and the stiffness of the foam increases and approaches a value equal to that of solid polyurethane. When the foam is loaded in tension, the cell walls are damaged and the foam fractures. A constitutive theory for rigid polyurethane foam has been developed. This theory is based on a decomposition of the foam into two parts: a skeleton and a nonlinear elastic continuum in parallel. The skeleton accounts for the foam behavior in the elastic and plateau regimes and is described using a coupled plasticity with continuum damage theory. The nonlinear elastic continuum accounts for the lock-up of the foam due to internal gas pressure and cell wall interactions. This new constitutive theory has been implemented in both static and dynamic finite element codes. Numerical simulations performed using the new constitutive theory are presented.

  3. Fast collision detection for fracturing rigid bodies.

    PubMed

    Glondu, Loeiz; Schvartzman, Sara C; Marchal, Maud; Dumont, Georges; Otaduy, Miguel A

    2014-01-01

    In complex scenes with many objects, collision detection plays a key role in the simulation performance. This is particularly true in fracture simulation for two main reasons. One is that fracture fragments tend to exhibit very intensive contact, and the other is that collision detection data structures for new fragments need to be computed on the fly. In this paper, we present novel collision detection algorithms and data structures for real-time simulation of fracturing rigid bodies. We build on a combination of well-known efficient data structures, namely, distance fields and sphere trees, making our algorithm easy to integrate on existing simulation engines. We propose novel methods to construct these data structures, such that they can be efficiently updated upon fracture events and integrated in a simple yet effective self-adapting contact selection algorithm. Altogether, we drastically reduce the cost of both collision detection and collision response. We have evaluated our global solution for collision detection on challenging scenarios, achieving high frame rates suited for hard real-time applications such as video games or haptics. Our solution opens promising perspectives for complex fracture simulations involving many dynamically created rigid objects. PMID:24201324

  4. Fast Collision Detection for Fracturing Rigid Bodies.

    PubMed

    Glondu, Loeiz; Schvartzman, Sara C; Marchal, Maud; Dumont, Georges; Otaduy, Miguel A

    2013-07-01

    In complex scenes with many objects, collision detection plays a key role in the simulation performance. This is particularly true in fracture simulation for two main reasons. One is that fracture fragments tend to exhibit very intensive contact, and the other is that collision detection data structures for new fragments need to be computed on the fly. In this paper, we present novel collision detection algorithms and data structures for real-time simulation of fracturing rigid bodies. We build on a combination of well-known efficient data structures, namely distance fields and sphere trees, making our algorithm easy to integrate on existing simulation engines. We propose novel methods to construct these data structures, such that they can be efficiently updated upon fracture events and integrated in a simple yet effective self-adapting contact selection algorithm. Altogether, we drastically reduce the cost of both collision detection and collision response. We have evaluated our global solution for collision detection on challenging scenarios, achieving high frame rates suited for hard real-time applications such as video games or haptics. Our solution opens promising perspectives for complex fracture simulations involving many dynamically created rigid objects. PMID:23836702

  5. 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.

  6. 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

  7. 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…

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 24 CFR 242.2 - Program financial self-sufficiency.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Program financial self-sufficiency... self-sufficiency and actuarial soundness; i.e., to avoid mortgage defaults and claims for insurance... AUTHORITIES MORTGAGE INSURANCE FOR HOSPITALS General Eligibility Requirements § 242.2 Program financial...

  14. Stability of binaries. Part 1: Rigid binaries

    NASA Astrophysics Data System (ADS)

    Sharma, Ishan

    2015-09-01

    We consider the stability of binary asteroids whose members are possibly granular aggregates held together by self-gravity alone. A binary is said to be stable whenever each member is orbitally and structurally stable to both orbital and structural perturbations. To this end, we extend the stability test for rotating granular aggregates introduced by Sharma (Sharma, I. [2012]. J. Fluid Mech., 708, 71-99; Sharma, I. [2013]. Icarus, 223, 367-382; Sharma, I. [2014]. Icarus, 229, 278-294) to the case of binary systems comprised of rubble members. In part I, we specialize to the case of a binary with rigid members subjected to full three-dimensional perturbations. Finally, we employ the stability test to critically appraise shape models of four suspected binary systems, viz., 216 Kleopatra, 25143 Itokawa, 624 Hektor and 90 Antiope.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Coherent distributions for the rigid rotator

    NASA Astrophysics Data System (ADS)

    Grigorescu, Marius

    2016-06-01

    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.

  1. CHARACTERIZATION OF A RIGID BARRIER FILTER SYSTEM

    SciTech Connect

    Chiang, Ta-Kuan

    2001-11-06

    A mathematical model is formulated to describe the dynamics of a rigid barrier filter system. Complete with filtration, regeneration and particle re-deposition, this model provides sizing information for new filter systems and diagnostic information for operating filter systems. To turn this model into a practical and smart filter system predictive model, monitoring devices for variables such as real-time particle concentration and size distribution are currently under laboratory development. The program goal is to introduce a smart filter system to supervise its operation and to assure its system reliability. Primarily, a smart filter system will update operating information, sound up malfunction alarms, and provide self-activated measures such as adjusting the cleaning frequency, intensity and back-pulse duration.

  2. Weak rigidity in almost-thermodynamic material schemes

    SciTech Connect

    del Olmo, V.; Olivert, J.

    1985-06-01

    To avoid the restrictions that the Born rigidity supposes for the motions in relativity, the definition of a weakly rigid almost-thermodynamic material scheme is proposed. From it the relativistic incompressibility condition given by Ferrando and Olivert is obtained. Moreover, it is proved that, for the weakly rigid irrotational and geodesic almost-thermodynamic material schemes, the scalar curvature of the Landau manifolds is constant along the streamlines.

  3. Quasiclassical trajectory studies of rigid rotor--rigid surface scattering. I. Flat surface

    SciTech Connect

    Bowman, J.M.; Park, S.C.

    1982-12-01

    Rotationally inelastic transition intensities are calculated for a model N/sub 2/ rigid rotor--rigid flat surface at initial collision energies of 104 and 3800 meV and for many initial beam orientations. The interaction potential is a Morse function modulated by a term which depends on the rotor orientation angle. The calculations are based on the quasiclassical trajectory method and a distorted trajectory perturbation theory. At the low collision energy the rotational excitation is mediated by the attractive part of the potential and by the repulsive part at high energies. The collision dynamics is direct in both energy regimes, however, quite complicated in the former one. Rotational rainbows are clearly observed for the high energy collisions.

  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. Rigid internal fixation with titanium versus bioresorbable miniplates in the repair of mandibular fractures in rabbits.

    PubMed

    Hochuli-Vieira, E; Cabrini Gabrielli, M A; Pereira-Filho, V A; Gabrielli, M F R; Padilha, J G

    2005-03-01

    The purpose of this study was to compare by qualitative histology the efficacy of rigid internal fixation with titanium system and the Lacto Sorb system in mandibular fractures in rabbits. Thirty male adult rabbits Oryctolagus cuniculus were used. Unilateral mandibular osteotomies were performed between the canine and first premolar. The animals were divided into two groups: for Group I-rigid internal fixation was performed with titanium system 1.5 mm (Synthes, Oberdorf, Switzerland), with two screws of 6 mm (bicortical) on each side of the osteotomy. For Group II-rigid internal fixation was performed with PLLA/PGA system 1.5 mm (Lacto Sorb, WLorenz, Jacksonville, FL, USA). The histological analysis evaluated the presence of inflammatory reaction, degree of bone healing and degree of resorption of the Lacto Sorb screws. The results of both fixation systems were similar, only with a small difference after 15 and 30 days. In Group I a faster bony healing was noted. But after 60 days, bony healing was similar in both groups. It is concluded that both PLLA/PGA and titanium plates and screws provide sufficient strength to permit mandibular bone healing. The resorption process of PLLA/PGA osteosynthesis material did not cause acute or chronic inflammatory reaction or foreign body reaction during the studied period.

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

    ERIC Educational Resources Information Center

    Yanik, Huseyin Bahadir; Flores, Alfinio

    2009-01-01

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

  7. 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…

  8. Lift on Flexible and Rigid Cambered Wings at High Incidence

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    The effects of camber and camber change due to elastic deflection of a membrane wing were investigated for wings in rectilinear translation with parameter variations in wing incidence and acceleration. Direct force and moment measurements were performed on a rigid flat plate wing, rigid cambered wings, and a membrane wing. Features in the force histories were further examined via flow visualization by planar laser illumination of fluorescent dye. Below 10 degrees of incidence, Wagner's approximation accurately predicts the time-evolution of lift for the rigid wings. At higher incidence, flow separation results in force transients, and the effect of wing camber is no longer additive. Both the rigid flat plate and rigid cambered wings reach peak lift at a 35 degree angle of attack, whereas the flexible wing experiences stall delay and reaches peak lift at 50 degrees. Due to the aeroelasticity of the flexible membrane, flow over the suction surface remains attached for much higher incidence angles than for the rigid wings. For incidence angles less than 30 degrees, the peak lift of the flexible wing is lower than that of its rigid counterparts. Beyond 30 degrees, the flexible wing experiences an aeroelastically induced stall delay that allows lift to exceed the rigid analogs. This work was supported by the Air Force Office of Scientific Research (AFOSR) Summer Faculty Fellowship Program and the U.S. Army Research Laboratory under the Micro Autonomous Systems and Technology (MAST) program.

  9. 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 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....

  10. 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 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....

  11. 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....

  12. 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 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....

  13. Perceptual, cognitive, and personality rigidity in Parkinson's disease.

    PubMed

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

    2015-03-01

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

  14. 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....

  15. 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.

  16. 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

  17. Rigidity sensing and adaptation through regulation of integrin types.

    PubMed

    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

    2014-06-01

    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

  18. 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.

  19. Spontaneous droplet trampolining on rigid superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Schutzius, Thomas M.; Jung, Stefan; Maitra, Tanmoy; Graeber, Gustav; Köhme, Moritz; Poulikakos, Dimos

    2015-11-01

    Spontaneous removal of condensed matter from surfaces is exploited in nature and in a broad range of technologies to achieve self-cleaning, anti-icing and condensation control. But despite much progress, our understanding of the phenomena leading to such behaviour remains incomplete, which makes it challenging to rationally design surfaces that benefit from its manifestation. Here we show that water droplets resting on superhydrophobic textured surfaces in a low-pressure environment can self-remove through sudden spontaneous levitation and subsequent trampoline-like bouncing behaviour, in which sequential collisions with the surface accelerate the droplets. These collisions have restitution coefficients (ratios of relative speeds after and before collision) greater than unity despite complete rigidity of the surface, and thus seemingly violate the second law of thermodynamics. However, these restitution coefficients result from an overpressure beneath the droplet produced by fast droplet vaporization while substrate adhesion and surface texture restrict vapour flow. We also show that the high vaporization rates experienced by the droplets and the associated cooling can result in freezing from a supercooled state that triggers a sudden increase in vaporization, which in turn boosts the levitation process. This effect can spontaneously remove surface icing by lifting away icy drops the moment they freeze. Although these observations are relevant only to systems in a low-pressure environment, they show how surface texturing can produce droplet-surface interactions that prohibit liquid and freezing water-droplet retention on surfaces.

  20. 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.

  1. Spontaneous droplet trampolining on rigid superhydrophobic surfaces.

    PubMed

    Schutzius, Thomas M; Jung, Stefan; Maitra, Tanmoy; Graeber, Gustav; Köhme, Moritz; Poulikakos, Dimos

    2015-11-01

    Spontaneous removal of condensed matter from surfaces is exploited in nature and in a broad range of technologies to achieve self-cleaning, anti-icing and condensation control. But despite much progress, our understanding of the phenomena leading to such behaviour remains incomplete, which makes it challenging to rationally design surfaces that benefit from its manifestation. Here we show that water droplets resting on superhydrophobic textured surfaces in a low-pressure environment can self-remove through sudden spontaneous levitation and subsequent trampoline-like bouncing behaviour, in which sequential collisions with the surface accelerate the droplets. These collisions have restitution coefficients (ratios of relative speeds after and before collision) greater than unity despite complete rigidity of the surface, and thus seemingly violate the second law of thermodynamics. However, these restitution coefficients result from an overpressure beneath the droplet produced by fast droplet vaporization while substrate adhesion and surface texture restrict vapour flow. We also show that the high vaporization rates experienced by the droplets and the associated cooling can result in freezing from a supercooled state that triggers a sudden increase in vaporization, which in turn boosts the levitation process. This effect can spontaneously remove surface icing by lifting away icy drops the moment they freeze. Although these observations are relevant only to systems in a low-pressure environment, they show how surface texturing can produce droplet-surface interactions that prohibit liquid and freezing water-droplet retention on surfaces. PMID:26536959

  2. Rigid multipodal platforms for metal surfaces.

    PubMed

    Valášek, Michal; Lindner, Marcin; Mayor, Marcel

    2016-01-01

    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

  3. Rigid-rotor, field-reversed configuration

    SciTech Connect

    Conti, F. Giammanco, F.; Wessel, F. J.; Binderbauer, M. W.; Bolte, N.; Morehouse, M.; Qerushi, A.; Rahman, H. U.; Roche, T.; Slepchenkov, M.

    2014-02-15

    The radial profiles, n(r), B{sub z}(r), and E{sub r}(r), for a Flux-Coil (“inductively driven”), Field-Reversed Configuration (FC-FRC) are measured and compared to the predictions of the Rigid-Rotor Model (RRM), which is an analytic, one-dimensional, time-independent, equilibrium description for the FRC. Injectors mounted on both ends of the confinement vessel provide a pre-fill plasma. Coaxial coils mounted outside the vacuum boundaries of the annular-confinement vessel accelerate the plasma and produce the FRC. The density profile is measured by laser interferometry, the magnetic-field profile using an in-situ probe array, and the electric-field profile using an in-situ, floating-probe array. Free parameters for each profile are measured, which also allow other intrinsic-plasma parameters to be determined, using computer-fit algorithms: null radius, radial thickness, plasma temperature, rotation frequencies, the latter of which are independently verified by spectroscopy. All radial profiles agree with the RRM predictions, for the experimental configuration, parameter regime, and specified-time interval studied here.

  4. Sextic potential for \\gamma -rigid prolate nuclei

    NASA Astrophysics Data System (ADS)

    Buganu, P.; Budaca, R.

    2015-10-01

    The equation of the Bohr-Mottelson Hamiltonian with a sextic oscillator potential is solved for γ -rigid prolate nuclei. The associated shape phase space is reduced to three variables which are exactly separated. The angular equation has the spherical harmonic functions as solutions, while the β equation is converted to the quasi-exactly solvable case of the sextic oscillator potential with a centrifugal barrier. The energies and the corresponding wave functions are given in closed form and depend, up to a scaling factor, on a single parameter. The {0}+ and {2}+ states are exactly determined, having an important role in the assignment of some ambiguous states for the experimental β bands. Due to the special properties of the sextic potential, the model can simulate, by varying the free parameter, a shape phase transition from a harmonic to an anharmonic prolate β -soft rotor crossing through a critical point. Numerical applications are performed for 39 nuclei: {}98-108Ru, {}{100,102}Mo, {}116-130Xe, {}{132,134}Ce, {}146-150Nd, {}{150,152}Sm, {}{152,154}Gd, {}{154,156}Dy, 172Os, {}180-196Pt, 190Hg and 222Ra. The best candidates for the critical point are found to be 104Ru and {}{120,126}Xe, followed closely by 128Xe, 172Os, 196Pt and 148Nd.

  5. 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.

  6. 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

  7. 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

  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. Effect of rigid gas permeable lens flexure on vision.

    PubMed

    Sorbara, L; Fonn, D; MacNeill, K

    1992-12-01

    The flexure of spherical rigid lenses (various materials) and a soft lens was measured using automated over-keratometry on 6 adapted rigid lens wearers (12 eyes) whose corneal toricity ranged from 1.37 to 3.87 D. The results showed: (1) that there was no significant difference in flexure between polymethyl methacrylate (PMMA), silicone acrylate, and the fluorosilicone acrylate lenses (whose Dks ranged from 0 to 115). However, Advent (fluoropolymer) did flex significantly more than the other rigid lenses, and significantly less than the soft lens (Bausch & Lomb U4) and (2) that lens flexure of the rigid lenses did not alter over a 2-h period. We also measured high and low contrast visual acuity (HCVA and LCVA), and the results from subjects wearing Advent and the soft lens were significantly worse than with the other rigid lenses. Finally, the results of this study showed no correlation between rigid lens flexure and permeability and between rigid lens flexure and visual acuity when Advent was excluded from the linear regression analysis.

  10. 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

  11. 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.

  12. Sufficiency, justice, and the pursuit of health extension.

    PubMed

    Farrelly, Colin

    2007-12-01

    According to one account of distributive justice, called the Sufficiency View, justice only requires that we bring everyone above some critical threshold of well-being and nothing more. This account of justice no doubt explains why some people believe it is unfair to invest scarce public funds into combating aging. In this paper I show why the sufficiency view is wrong. Furthermore, I argue that the real injustice occurs when we disparage or ignore all potential avenues of extending healthy living. We must be both ambitious and imaginative in our attitudes towards health extension.

  13. Nematic order by elastic interactions and cellular rigidity sensing

    NASA Astrophysics Data System (ADS)

    Friedrich, B. M.; Safran, S. A.

    2011-01-01

    We predict spontaneous nematic order in an ensemble of active force generators with elastic interactions as a minimal model for early nematic alignment of short stress fibers in non-motile, adhered cells. Mean-field theory is formally equivalent to Maier-Saupe theory for a nematic liquid. However, the elastic interactions are long-ranged (and thus depend on cell shape and matrix elasticity) and originate in cell activity. Depending on the density of force generators, we find two regimes of cellular rigidity sensing for which orientational, nematic order of stress fibers depends on matrix rigidity either in a step-like manner or with a maximum at an optimal rigidity.

  14. 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

  15. A stable fluid-structure-interaction solver for low-density rigid bodies using the immersed boundary projection method

    NASA Astrophysics Data System (ADS)

    Lācis, Uǧis; Taira, Kunihiko; Bagheri, Shervin

    2016-01-01

    Dispersion of low-density rigid particles with complex geometries is ubiquitous in both natural and industrial environments. We show that while explicit methods for coupling the incompressible Navier-Stokes equations and Newton's equations of motion are often sufficient to solve for the motion of cylindrical particles with low density ratios, for more complex particles - such as a body with a protrusion - they become unstable. We present an implicit formulation of the coupling between rigid body dynamics and fluid dynamics within the framework of the immersed boundary projection method. Similarly to previous work on this method, the resulting matrix equation in the present approach is solved using a block-LU decomposition. Each step of the block-LU decomposition is modified to incorporate the rigid body dynamics. We show that our method achieves second-order accuracy in space and first-order in time (third-order for practical settings), only with a small additional computational cost to the original method. Our implicit coupling yields stable solution for density ratios as low as 10-4. We also consider the influence of fictitious fluid located inside the rigid bodies on the accuracy and stability of our method.

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

    PubMed Central

    Burke, Jeffrey M.; Pandit, Kunal R.; Goertz, John P.

    2014-01-01

    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 107, 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%. PMID:25538814

  17. 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

  18. 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.…

  19. The First Amendment at Its Bicentennial: Necessary but Not Sufficient?

    ERIC Educational Resources Information Center

    Teeter, Dwight L., Jr.

    1992-01-01

    Questions whether an eighteenth-century protection for freedom of the press (the First Amendment) is sufficient for the challenges that the nation's press faces in the twentieth century. Examines prior restraints and seditious libel. Finds instances in which those abuses are alive and well and potentially threatening. (PRA)

  20. 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.

  1. 40 CFR 350.13 - Sufficiency of assertions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... submitter uses it, and competitors cannot easily duplicate the specific use of this chemical through their... title does not contain sufficient information to enable competitors to determine the specific chemical... competitors cannot readily discover the specific chemical identity by analysis of the submitter's products...

  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. Exploring Necessary and Sufficient Conditions in Dynamic Geometry Environments

    ERIC Educational Resources Information Center

    Leung, Allen; Chan, Yip-Cheung

    2006-01-01

    This paper describes a possible dragging experiment in a dynamic geometry environment (DGE) that explores a necessary and sufficient condition for cyclic quadrilateral. The dragging modalities identified by Arzarello, Olivero, Paola, and Robutti (2002) and the functions of variation realized in DGE discussed by Leung (2003) will be used as tools…

  4. 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 its newest…

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

    PubMed

    Lynch, Robert E; Hack, Richard A

    2010-07-01

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

  6. 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

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

    PubMed Central

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

    2010-01-01

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

  8. The Torsional Rigidity of Twist-Storing Polymers

    NASA Astrophysics Data System (ADS)

    Moroz, J. David; Nelson, Philip

    1998-03-01

    The statistical mechanics of a torsionally constrained polymer is investigated. We consider an inextensible chain with bend rigidity A and twist rigidity C. Through the relation Lk = Tw + Wr, the bend fluctuations must respond to an applied torque. We investigate this response and find excellent agreement between the predictions of our model and the experimental results on single λ-DNA molecules due to Strick et al. [Science 271 (1996) 1835]. This analysis affords an experimental determination of the microscopic twist rigidity C. Quantitative agreement between theory and experiment is obtained using C=120 nm. The theory further predicts a thermal reduction of the twist rigidity C induced by bend fluctuations. A confirmation of this result awaits further experiments.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. Rigidity of various fixation methods used as dental splints.

    PubMed

    Oikarinen, K; Andreasen, J O; Andreasen, F M

    1992-06-01

    Horizontal and vertical rigidity of teeth fixed with seven types of dental splints were evaluated by two tooth mobility measuring devices. Altogether 21 dissected sheep mandibles including soft tissues were used for the experiments in which Fermit, flexible wire-composite, Kevlar, Fiber, Protemp, rigid wire-composite and Triad Gel splints were applied to four incisors. The mean rigidity of the central incisors within the splint was measured by means of Mühlemann periodontometer (horizontal mobility) and Periotest (horizontal and vertical mobilities). Mobility values of teeth before splinting were used as covariants and the values with the splints were illustrated as adjusted mobility. Statistical significance between the rigidity of various splints was analyzed by an unpaired t-test. It was shown that the most rigid splints both in horizontal and vertical directions were Triad Gel, rigid wire-composite and Fermit splints. Kevlar and Fiber splint allowed more horizontal movement than other splints. Protemp and flexible wire-composite splints proved to produce adequate lateral support for the fixed teeth and allowed vertical flexibility which is experimentally known to improve periodontal healing of luxated teeth.

  14. 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.

  15. 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.

  16. 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. PMID:25225770

  17. 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.

  18. CSM and the myth of self-sufficiency.

    PubMed

    Harvey, P D

    1984-01-01

    The author of this letter asserts that self-sufficiency should not be regarded as a goal for contraceptive social marketing programs. Rather, the emphasis should be on increasing the number and effectiveness of social marketing programs. There will be a need for subsidized family planning programs as long as there is poverty. The only way a social marketing program can achieve financial self-sufficiency is to price contraceptives beyond the reach of the intended beneficiaries of the program. At present, condom buyers in Bangladesh spend about US$1/year for contraceptives purchased through the social marketing program; this amount is equivalent to 1 day's wage. Although contraceptive social marketing programs may seem expensive, their tremendous success in reaching ever growing numbers of rural and urban constantly reduces the cost for each couple supplied with contraception. Moreover, unlike most other family planning programs, contraceptive social marketing projects do recover at least a small part of their costs through sales. PMID:12313291

  19. 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).

  20. China's campaign for petroleum self-sufficiency well under way

    SciTech Connect

    Not Available

    1994-05-09

    China's petrochemical expansion boom is in full swing. With what some measure as the world's fastest growing economy, China's consumer products demand is growing at a voracious pace, spurring sky rocketing demand for basic and intermediate petrochemicals. So Beijing has embarked on a massive expansion of the nation's petrochemical industry to accommodate that growth. For the next 3 years at least, China will have to rely on imports for about half of its petrochemical supplies. China's rate of self-sufficiency by 1995 is expected to be 50--60% for ethylene, 60--70% for plastics, 70--80% for synthetic fibers, and 50--60% for synthetic rubber. For many key petrochemicals, China envisions accomplishing no less than self-sufficiency by the turn of the century. But to get to that point, Beijing must import foreign technology and capital needed for a wholesale upgrading and expansion of its petrochemical sector. In getting there, it must overcome conflicts involving projects pursued independently by certain local or provincial governments as well as by various state owned companies and agencies. And it must contend with an international petrochemical market still struggling to recover from a downturn that might not be able to absorb the loss of a major market as China moves toward self-sufficiency. The paper discusses capacity and expansion plans, especially for ethylene.

  1. 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.

  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). PMID:22122251

  3. Rigidity analysis of protein biological assemblies and periodic crystal structures

    PubMed Central

    2013-01-01

    Background We initiate in silico rigidity-theoretical studies of biological assemblies and small crystals for protein structures. The goal is to determine if, and how, the interactions among neighboring cells and subchains affect the flexibility of a molecule in its crystallized state. We use experimental X-ray crystallography data from the Protein Data Bank (PDB). The analysis relies on an effcient graph-based algorithm. Computational experiments were performed using new protein rigidity analysis tools available in the new release of our KINARI-Web server http://kinari.cs.umass.edu. Results We provide two types of results: on biological assemblies and on crystals. We found that when only isolated subchains are considered, structural and functional information may be missed. Indeed, the rigidity of biological assemblies is sometimes dependent on the count and placement of hydrogen bonds and other interactions among the individual subchains of the biological unit. Similarly, the rigidity of small crystals may be affected by the interactions between atoms belonging to different unit cells. We have analyzed a dataset of approximately 300 proteins, from which we generated 982 crystals (some of which are biological assemblies). We identified two types of behaviors. (a) Some crystals and/or biological assemblies will aggregate into rigid bodies that span multiple unit cells/asymmetric units. Some of them create substantially larger rigid cluster in the crystal/biological assembly form, while in other cases, the aggregation has a smaller effect just at the interface between the units. (b) In other cases, the rigidity properties of the asymmetric units are retained, because the rigid bodies did not combine. We also identified two interesting cases where rigidity analysis may be correlated with the functional behavior of the protein. This type of information, identified here for the first time, depends critically on the ability to create crystals and biological assemblies

  4. Controlled trial of a semi-rigid bandage ('Scotchrap') in patients with ankle ligament lesions.

    PubMed

    Johannes, E J; Sukul, D M; Spruit, P J; Putters, J L

    1993-01-01

    A randomized, controlled, parallel-group study was performed to compare the clinical efficacy of a semi-rigid bandage ('Scotchrap') with the standard adhesive tape treatment for ankle ligament injuries. The semi-rigid bandage support wrap consists of a knitted fibreglass fabric impregnated with a polyurethane resin. The cotton stockinet and the synthetic cast padding are used for protection of pressure points and any bony prominences. Prior to application, the 'Scotchrap' must be soaked in water after which it is applied in a way similar to that used for a plaster of paris bandage. The finished bandage remains elastic, allowing normal dorsal and plantar flexion of the foot, but preventing inversion and eversion, and pronation and supination. At rest, the bandage always redresses the immobilized ankle into the neutral position. One hundred and thirty-six patients were included in the study. The semi-rigid bandage group comprised 59 patients and the tape group had 57 patients. These two groups were statistically comparable. The intake questionnaire included a general and a specific anamnesis form as well as a physical examination form. Follow-up data were recorded every 2 weeks. After termination of the treatment, the patients evaluated treatment efficacy. Statistical analysis of 126 items per patient with chi 2-tests (p < or = 0.05) and Fisher's exact tests (p < or = 0.05) revealed no statistical significant differences in treatment result. The patient assessments of treatment efficacy of both types of bandage were also comparable. Both types of bandage gave sufficient stability (98%; p < 0.005) and were equally effective.(ABSTRACT TRUNCATED AT 250 WORDS)

  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. 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. PMID:12223827

  7. NON-RIGID IMAGE REGISTRATION BASED STRAIN ESTIMATOR FOR INTRAVASCULAR ULTRASOUND ELASTOGRAPHY

    PubMed Central

    Richards, Michael S.; Doyley, Marvin M.

    2013-01-01

    Intravascular ultrasound elastography (IVUSe) could improve the diagnosis of cardiovascular disease by revealing vulnerable plaques through their mechanical tissue properties. To improve the performance of IVUSe, we developed and implemented a non-rigid image-registration method to visualize the radial and circumferential component of strain within vascular tissues. We evaluated the algorithm’s performance with four initialization schemes using simulated and experimentally acquired ultrasound images. Applying the registration method to radio-frequency (RF) echo frames improved the accuracy of displacements compared to when B-mode images were employed. However, strain elastograms measured from RF echo frames produce erroneous results when both the zero-initialization method and the mesh-refinement scheme were employed. For most strain levels, the cross-correlation-initialization method produced the best performance. The simulation study predicted that elastograms obtained from vessels with average strains in the range of 3%–5% should have high elastographic signal-to-noise ratio (SNRe)–on the order of 4.5 and 7.5 for the radial and circumferential components of strain, respectively. The preliminary in vivo validation study (phantom and an atherosclerotic rabbit) demonstrated that the non-rigid registration method could produce useful radial and circumferential strain elastograms under realistic physiologic conditions. The results of this investigation were sufficiently encouraging to warrant a more comprehensive in vivo validation. PMID:23245827

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Packing density of rigid aggregates is independent of scale.

    PubMed

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

    2014-06-24

    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

  16. 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.

  17. 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.

  18. 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. PMID:27018779

  19. 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

  20. 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. PMID:25737056

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Is recurrent processing necessary and/or sufficient for consciousness?

    PubMed

    Tsuchiya, Naotsugu; van Boxtel, Jeroen J A

    2010-09-01

    Abstract Abstract While we agree with Lamme's general framework, we are not so convinced by his mapping between psychological concepts with their underlying neuronal mechanisms. Specifically, we doubt if recurrent processing is either necessary or sufficient for consciousness. A gist of a scene may be consciously perceived by purely feedforward, without recurrent, processing. Neurophysiological studies of perceptual suppression show recurrent processing in visual cortex for consciously invisible objects. While the neuronal correlates of attention and consciousness remain to be clarified, we agree with Lamme that these two processes are independent, evinced by our recent demonstration of opposing effects of attention and consciousness. PMID:24168345

  6. 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...

  7. 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...

  8. Sequences Sufficient for Programming Imprinted Germline DNA Methylation Defined

    PubMed Central

    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. PMID:22403732

  9. Photon underproduction crisis: Are QSOs sufficient to resolve it?

    NASA Astrophysics Data System (ADS)

    Khaire, Vikram; Srianand, Raghunathan

    2015-07-01

    We investigate the recent claim of `photon underproduction crisis' by Kollmeier et al. which suggests that the known sources of ultraviolet (UV) radiation may not be sufficient to generate the inferred H I photoionization rate (Γ _{H I}) in the low-redshift intergalactic medium. Using the updated QSO emissivities from the recent studies and our cosmological radiative transfer code developed to estimate the UV background, we show that the QSO contributions to Γ _{H I} is higher by a factor ˜2 as compared to the previous estimates. Using self-consistently computed combinations of star formation rate density and dust attenuation, we show that a typical UV escape fraction of 4 per cent from star-forming galaxies should be sufficient to explain the inferred Γ _{H I} by Kollmeier et al. Interestingly, we find that the contribution from QSOs alone can explain the recently inferred Γ _{H I} by Shull et al. which used the same observational data but different simulation. Therefore, we conclude that the crisis is not as severe as it was perceived before and there seems no need to look for alternate explanations such as low luminosity hidden QSOs or decaying dark matter particles.

  10. Perinatal tolerance to proinsulin is sufficient to prevent autoimmune diabetes

    PubMed Central

    Jhala, Gaurang; Chee, Jonathan; Trivedi, Prerak M.; Selck, Claudia; Gurzov, Esteban N.; Graham, Kate L.; Thomas, Helen E.; Kay, Thomas W.H.; Krishnamurthy, Balasubramanian

    2016-01-01

    High-affinity self-reactive thymocytes are purged in the thymus, and residual self-reactive T cells, which are detectable in healthy subjects, are controlled by peripheral tolerance mechanisms. Breakdown in these mechanisms results in autoimmune disease, but antigen-specific therapy to augment natural mechanisms can prevent this. We aimed to determine when antigen-specific therapy is most effective. Islet autoantigens, proinsulin (PI), and islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP) were expressed in the antigen-presenting cells (APCs) of autoimmune diabetes-prone nonobese diabetic (NOD) mice in a temporally controlled manner. PI expression from gestation until weaning was sufficient to completely protect NOD mice from diabetes, insulitis, and development of insulin autoantibodies. Insulin-specific T cells were significantly diminished, were naive, and did not express IFN-γ when challenged. This long-lasting effect from a brief period of treatment suggests that autoreactive T cells are not produced subsequently. We tracked IGRP206–214-specific CD8+ T cells in NOD mice expressing IGRP in APCs. When IGRP was expressed only until weaning, IGRP206–214-specific CD8+ T cells were not detected later in life. Thus, anti-islet autoimmunity is determined during early life, and autoreactive T cells are not generated in later life. Bolstering tolerance to islet antigens in the perinatal period is sufficient to impart lasting protection from diabetes.

  11. Perinatal tolerance to proinsulin is sufficient to prevent autoimmune diabetes

    PubMed Central

    Jhala, Gaurang; Chee, Jonathan; Trivedi, Prerak M.; Selck, Claudia; Gurzov, Esteban N.; Graham, Kate L.; Thomas, Helen E.; Kay, Thomas W.H.; Krishnamurthy, Balasubramanian

    2016-01-01

    High-affinity self-reactive thymocytes are purged in the thymus, and residual self-reactive T cells, which are detectable in healthy subjects, are controlled by peripheral tolerance mechanisms. Breakdown in these mechanisms results in autoimmune disease, but antigen-specific therapy to augment natural mechanisms can prevent this. We aimed to determine when antigen-specific therapy is most effective. Islet autoantigens, proinsulin (PI), and islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP) were expressed in the antigen-presenting cells (APCs) of autoimmune diabetes-prone nonobese diabetic (NOD) mice in a temporally controlled manner. PI expression from gestation until weaning was sufficient to completely protect NOD mice from diabetes, insulitis, and development of insulin autoantibodies. Insulin-specific T cells were significantly diminished, were naive, and did not express IFN-γ when challenged. This long-lasting effect from a brief period of treatment suggests that autoreactive T cells are not produced subsequently. We tracked IGRP206–214-specific CD8+ T cells in NOD mice expressing IGRP in APCs. When IGRP was expressed only until weaning, IGRP206–214-specific CD8+ T cells were not detected later in life. Thus, anti-islet autoimmunity is determined during early life, and autoreactive T cells are not generated in later life. Bolstering tolerance to islet antigens in the perinatal period is sufficient to impart lasting protection from diabetes. PMID:27699217

  12. Effect of Base Shape on Damping of Rocking of Rigid Body

    NASA Astrophysics Data System (ADS)

    Imanishi, Nozomu; Inoue, Yoshio; Shibata, Kyoko; Sato, Kazutomo; Yamasaki, Yoshihiko

    Effect of base shape on damping characteristics of rocking of rigid body is presented. We pay attention to the fact that free vibration amplitude of rigid body decreases rapidly without dampers or damping materials. We consider rocking of rigid body is very attractive as a low cost dynamic vibration absorber. At first, damping characteristics of rocking of typical rigid body with flat base shape is discussed theoretically. Next, we propose new type rigid body which base shape is polygon in order to design damping characteristics of rigid body in wide range. Theoretical method to calculate damping characteristics of rigid body is derived. Experiment of free vibration of the rigid body is carried out and the calculated results of the proposed method agree well with the experimental results. By calculating damping ratio of proposed rigid body using derived equations, it can be seen polygon base shape is very useful to design damping characteristics of rigid body.

  13. 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.

  14. Magnetic rigid rotor in the quantum regime: Theoretical toolbox

    NASA Astrophysics Data System (ADS)

    Rusconi, Cosimo C.; Romero-Isart, Oriol

    2016-02-01

    We describe the quantum dynamics of a magnetic rigid rotor in the mesoscopic scale where the Einstein-De Haas effect is predominant. In particular, we consider a single-domain magnetic nanoparticle with uniaxial anisotropy in a magnetic trap. Starting from the basic Hamiltonian of the system under the macrospin approximation, we derive a bosonized Hamiltonian describing the center-of-mass motion, the total angular momentum, and the macrospin degrees of freedom of the particle treated as a rigid body. This bosonized Hamiltonian can be approximated by a simple quadratic Hamiltonian that captures the rich physics of a nanomagnet tightly confined in position, nearly not spinning, and with its macrospin antialigned to the magnetic field. The theoretical tools derived and used here can be applied to other quantum mechanical rigid rotors.

  15. 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. PMID:25280165

  16. Matrix rigidity optimizes the polarization of stem cells

    NASA Astrophysics Data System (ADS)

    Zemel, Assaf; Rehfeldt, Florian; Brown, Andre; Discher, Dennis; Safran, Samuel

    2009-03-01

    We present a theoretical model and experiments to explain the non-monotonic dependence of stress-fiber polarization in stem cells on matrix rigidity. The theory generalizes the treatment of elastic inclusions to ``living'' inclusions (cells) whose active polarizability, unlike non-living matter, depends on the feedback of cellular forces that develop in response to matrix stresses. We demonstrate experimentally that the stress fibers in adult mesenchymal stem cells, generally orient parallel to the long axis of the cells, with an anisotropy that depends non-monotonically on substrate stiffness. Consistent with these experiments, our theory predicts that the magnitude of the cellular force increases monotonically with the matrix rigidity while the polarization anisotropy shows a maximum that depends on the cell shape and the elastic modulus of the medium. These findings offer a mechanical correlate for the observation that stem cell differentiation optimizes in a range of matrix rigidities that depends on the tissue type.

  17. 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.

  18. 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.

  19. Compatibility of weak rigidity with some types of elastic schemes

    SciTech Connect

    del Olmo, V.; Olivert, J.

    1986-04-01

    The behavior of the hypoelastic-Synge, hypoelastic-Maugin, and hypoelastic-Carter and Quintana almost-thermodynamic material schemes, under weak rigidity hypotheses, is studied. In every case, the absence of principal transverse shock waves (or the vanishing of the corresponding speeds) is obtained. The same result follows for the longitudinal shock waves when the Lame coefficient ..mu.. does not vanish. A definition of an elastic almost-thermodynamic material scheme based on the Fermi--Walker transport is proposed and compared with the above elastic schemes. The speeds of the principal shock waves associated are attained and its compatibility with the Ferrando--Olivert incompressibility condition is proved. In the presence of weak rigidity the elastic schemes here defined lead (assuming ..mu..not =0) to the Born-rigidity condition.

  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. PMID:11370381

  1. 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.

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

    PubMed

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

    2014-02-01

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

  3. On the rigidity of polynorbornenes with dipolar pendant groups.

    PubMed

    Lin, Wei-Yu; Murugesh, Modachur G; Sudhakar, Sundarraj; Yang, Hsiao-Ching; Tai, Hwan-Ching; Chang, Chia-Seng; Liu, Yi-Hung; Wang, Yu; Chen, I-Wen Peter; Chen, Chun-Hsien; Luh, Tien-Yau

    2005-12-16

    A range of polynorbornenes (PNBs) with fused dipolar pendant groups at C-5,6 positions was synthesized by ring-opening metathesis polymerization catalyzed by a ruthenium carbene complex (Grubbs I). Photophysical studies, EFISH measurements, and atomic force microscopy images have been used to investigate the structures and morphology of these polymers. These results suggest that the polymers may adopt rigid rod-like structures. The presence of the double bonds in PNBs appeared to be indispensable for the rigidity of the polymers. Interaction between unsaturated pendant groups may result in coherent alignment leading to a rod-like structure.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

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

    PubMed

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

    2014-02-01

    We provide conditions under which 2D digital images preserve their topological properties under rigid transformations. We consider the two most common digital topology models, namely dual adjacency and well-composedness. This paper leads to the proposal of optimal preprocessing strategies that ensure the topological invariance of images under arbitrary rigid transformations. These results and methods are proved to be valid for various kinds of images (binary, gray-level, label), thus providing generic and efficient tools, which can be used in particular in the context of image registration and warping. PMID:26270925

  11. New generalizations of the integrable problems in rigid body dynamics

    NASA Astrophysics Data System (ADS)

    Yehia, H. M.

    1997-10-01

    We consider the general problem of motion of a rigid body about a fixed point under the action of an axisymmetric combination of potential and gyroscopic forces. We introduce six cases of this problem which are completely integrable for arbitrary initial conditions. The new cases generalize by several parameters all, but one, of the known results in the subject of rigid body dynamics. Namely, we generalize all the results due to Euler, Lagrange, Clebsch, Kovalevskaya, Brun and Lyapunov and also their subsequent generalizations by Rubanovsky and the present author.

  12. Conditions for the existence of the asymptotically pendulum motions of a rigid body with the center of mass on the main axis

    NASA Astrophysics Data System (ADS)

    Varkhalev, Iu. P.

    1988-07-01

    The first Liapunov method is used to investigate sufficient conditions for the existence of asymptotically pendulum motions of a rigid body with a single fixed point. A region of permissible values of the parameters characterizing the body mass corresponding to the asymptotically pendulum motions is defined. The existence of such motions in the case of the Kovalevskii solution and their absence in the Goriachev-Chapolygin solution are demonstrated.

  13. High Resolution Quantification of Cellular Forces for Rigidity Sensing

    NASA Astrophysics Data System (ADS)

    Liu, Shuaimin

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

  14. 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.

  15. Do safety issues of plasma products constrain self-sufficiency?

    PubMed

    Savidge, G F

    1994-12-01

    The ultimate responsibility for selecting and administering plasma products to patients rests with the prescribing physician, and it is for him/her to choose the safest product available. However, liability for a product with a full licence rests exclusively with the licence holder. After the problems of HIV and hepatitis C the safety of plasma-derived products has become of paramount importance. Particularly in the public sector, financial, strategic and political obstacles may adversely influence the quantity, quality and safety of plasma collection. The safety of blood products can be substantially enhanced by the harmonization of technical standards across both public and private sectors, thus supporting EC Directive 89/381. Additionally, the goal of European rather than national self-sufficiency should be encouraged.

  16. 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

  17. 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. PMID:20542940

  18. 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.

  19. Nonpetroleum mobility fuels and military-energy self-sufficiency

    SciTech Connect

    Freiwald, D.A.; Barattino, W.J.

    1981-01-01

    Nonpetroleum hydrocarbon fuels will likely serve as transition fuels for a few decades after petroleum sources become scarce. But nonpetroleum hydrocarbon fuels are ultimately either nonrenewable (e.g., coal and oil shale synfuels) or are inefficient to produce. Nuclear sources (supplemented by solar, geothermal, etc., as available) for electric power generation and hydrogen production provide a combination that can be used for military energy needs including mobility fuels, namely liquid hydrogen. This approach can give the military energy self-sufficiency for stationary needs as well as ground vehicles, ships, and aircraft. System integration concepts are discussed, and concepts for a methodology to evaluate source-to-use pathways for different classes of military bases are outlined.

  20. Are coarse scales sufficient for fast detection of visual threat?

    PubMed

    Mermillod, Martial; Droit-Volet, Sylvie; Devaux, Damien; Schaefer, Alexandre; Vermeulen, Nicolas

    2010-10-01

    It has recently been suggested that low-spatial-frequency information would provide rapid visual cues to the amygdala for basic but ultrarapid behavioral responses to dangerous stimuli. The present behavioral study investigated the role of different spatial-frequency channels in visually detecting dangerous stimuli belonging to living or nonliving categories. Subjects were engaged in a visual detection task involving dangerous stimuli, and subjects' behavioral responses were assessed in association with their fear expectations (induced by an aversive 90-dB white noise). Our results showed that, despite its crudeness, low-spatial-frequency information could constitute a sufficient signal for fast recognition of visual danger in a context of fear expectation. In addition, we found that this effect tended to be specific for living entities. These results were obtained despite a strong perceptual bias toward faster recognition of high-spatial-frequency stimuli under supraliminal perception durations.

  1. Meeting local energy needs: resources for self-sufficiency. [Monograph

    SciTech Connect

    Freedburg, M.

    1981-01-01

    The private sector, state and local governments, agencies, and the community itself will be the arenas for energy fund raising in the 1980s. This report surveys and describes these arenas, with references and key contacts accompanying each section. It explores two basic types of funding: (1) grants for community energy ventures of all kinds and (2) financing for consumers, both renters and homeowners, to purchase conservation measures. Grants are not going to be available in sufficient amounts to meet the need, but conservation loans are cost-effective in most parts of the country because they can be paid back through savings. Access to loans for low-income groups can be made available by grassroots funding, pension funds, bond financing, community-development funds, and other mechanisms. 59 references.

  2. [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

  3. Are coarse scales sufficient for fast detection of visual threat?

    PubMed

    Mermillod, Martial; Droit-Volet, Sylvie; Devaux, Damien; Schaefer, Alexandre; Vermeulen, Nicolas

    2010-10-01

    It has recently been suggested that low-spatial-frequency information would provide rapid visual cues to the amygdala for basic but ultrarapid behavioral responses to dangerous stimuli. The present behavioral study investigated the role of different spatial-frequency channels in visually detecting dangerous stimuli belonging to living or nonliving categories. Subjects were engaged in a visual detection task involving dangerous stimuli, and subjects' behavioral responses were assessed in association with their fear expectations (induced by an aversive 90-dB white noise). Our results showed that, despite its crudeness, low-spatial-frequency information could constitute a sufficient signal for fast recognition of visual danger in a context of fear expectation. In addition, we found that this effect tended to be specific for living entities. These results were obtained despite a strong perceptual bias toward faster recognition of high-spatial-frequency stimuli under supraliminal perception durations. PMID:20817781

  4. Rigidity, sensitivity and quality of attachment: the role of maternal rigidity in the early socio-emotional development of premature infants.

    PubMed

    Butcher, P R; Kalverboer, A F; Minderaa, R B; van Doormaal, E F; ten Wolde, Y

    1993-01-01

    The associations between a mother's rigidity, her sensitivity in early (3 month) interaction and the quality of her premature infant's attachment at 13 months were investigated. Rigidity as a personality characteristic was not found to be significantly associated with sensitivity or quality of attachment. Rigid attitudes to child rearing were related to sensitivity and to the responsivity of the infant. Rigid attitudes were not related to security of attachment. Infants who were rated less responsive at 3 months, however, tended to be less securely attached, and high Attitude Rigidity in the mother increased their chances of an insecure attachment.

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

    PubMed

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

    2012-01-01

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

  6. 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.

  7. Geometric and electrostatic modeling using molecular rigidity functions

    DOE PAGESBeta

    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

  8. Nonrigid registration using regularization that accomodates local tissue rigidity

    NASA Astrophysics Data System (ADS)

    Ruan, Dan; Fessler, Jeffrey A.; Roberson, Michael; Balter, James; Kessler, Marc

    2006-03-01

    Regularized nonrigid medical image registration algorithms usually estimate the deformation by minimizing a cost function, consisting of a similarity measure and a penalty term that discourages "unreasonable" deformations. Conventional regularization methods enforce homogeneous smoothness properties of the deformation field; less work has been done to incorporate tissue-type-specific elasticity information. Yet ignoring the elasticity differences between tissue types can result in non-physical results, such as bone warping. Bone structures should move rigidly (locally), unlike the more elastic deformation of soft issues. Existing solutions for this problem either treat different regions of an image independently, which requires precise segmentation and incurs boundary issues; or use an empirical spatial varying "filter" to "correct" the deformation field, which requires the knowledge of a stiffness map and departs from the cost-function formulation. We propose a new approach to incorporate tissue rigidity information into the nonrigid registration problem, by developing a space variant regularization function that encourages the local Jacobian of the deformation to be a nearly orthogonal matrix in rigid image regions, while allowing more elastic deformations elsewhere. For the case of X-ray CT data, we use a simple monotonic increasing function of the CT numbers (in HU) as a "rigidity index" since bones typically have the highest CT numbers. Unlike segmentation-based methods, this approach is flexible enough to account for partial volume effects. Results using a B-spline deformation parameterization illustrate that the proposed approach improves registration accuracy in inhale-exhale CT scans with minimal computational penalty.

  9. 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.

  10. Nonlinear optical properties of rigid-rod polymers

    NASA Technical Reports Server (NTRS)

    Trimmer, Mark S.; Wang, Ying

    1992-01-01

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

  11. 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. PMID:26074325

  12. Vibrational Modes and the Onset of Rigidity in Network Glasses

    NASA Astrophysics Data System (ADS)

    Joos, Bela; Plischke, Michael

    2001-03-01

    A covalently bonded network constrained by bond-bending and bond-stretching modes, according to a mean field theory argument, becomes rigid when the average coordination number of atoms exceeds 2.4 ^1. This result is confirmed by computer studies of the rigidity of model systems. Experimental studies also observe anomalies in the vibrational and thermal behaviour near 2.4. Some recent studies, such as in Ge_1-x Sex alloys, where Se, two-fold coordinated atoms, replace Ge atoms, report that the transition is a two-stage process. The evidence is in large part based on changes in the phonon spectrum rather than in the bulk elasticity. For this reason we have looked for signatures of the rigidity transition in the vibrational spectrum of a model four-fold coordinated material diluted by two-fold coordinated particles. We will report on our molecular dynamics studies of vibrational densities of states, focusing in particular on floppy modes and corner sharing modes. ^1For reviews of the experimental and theoretical work, see Rigidity Theory and Applications, eds. M.F. Thorpe and P.M. Duxbury (Kluwer Acad., NY, 1999).

  13. 21 CFR 876.5020 - External penile rigidity devices.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false External penile rigidity devices. 876.5020 Section 876.5020 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5020 External...

  14. 21 CFR 890.3610 - Rigid pneumatic structure orthosis.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  15. 21 CFR 890.3610 - Rigid pneumatic structure orthosis.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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…

  1. 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. PMID:27544113

  2. 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.

  3. 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.

  4. 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.

  5. “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

  6. 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

  7. 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

  8. 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).

  9. Arterial Stiffening Provides Sufficient Explanation for Primary Hypertension

    PubMed Central

    Pettersen, Klas H.; Bugenhagen, Scott M.; Nauman, Javaid; Beard, Daniel A.; Omholt, Stig W.

    2014-01-01

    Hypertension is one of the most common age-related chronic disorders, and by predisposing individuals for heart failure, stroke, and kidney disease, it is a major source of morbidity and mortality. Its etiology remains enigmatic despite intense research efforts over many decades. By use of empirically well-constrained computer models describing the coupled function of the baroreceptor reflex and mechanics of the circulatory system, we demonstrate quantitatively that arterial stiffening seems sufficient to explain age-related emergence of hypertension. Specifically, the empirically observed chronic changes in pulse pressure with age and the impaired capacity of hypertensive individuals to regulate short-term changes in blood pressure arise as emergent properties of the integrated system. The results are consistent with available experimental data from chemical and surgical manipulation of the cardio-vascular system. In contrast to widely held opinions, the results suggest that primary hypertension can be attributed to a mechanogenic etiology without challenging current conceptions of renal and sympathetic nervous system function. PMID:24853828

  10. 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

  11. Sufficient conditions of endemic threshold on metapopulation networks.

    PubMed

    Takaguchi, Taro; Lambiotte, Renaud

    2015-09-01

    In this paper, we focus on susceptible-infected-susceptible dynamics on metapopulation networks, where nodes represent subpopulations, and where agents diffuse and interact. Recent studies suggest that heterogeneous network structure between elements plays an important role in determining the threshold of infection rate at the onset of epidemics, a fundamental quantity governing the epidemic dynamics. We consider the general case in which the infection rate at each node depends on its population size, as shown in recent empirical observations. We first prove that a sufficient condition for the endemic threshold (i.e., its upper bound), previously derived based on a mean-field approximation of network structure, also holds true for arbitrary networks. We also derive an improved condition showing that networks with the rich-club property (i.e., high connectivity between nodes with a large number of links) are more prone to disease spreading. The dependency of infection rate on population size introduces a considerable difference between this upper bound and estimates based on mean-field approximations, even when degree-degree correlations are considered. We verify the theoretical results with numerical simulations.

  12. 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). PMID:22122247

  13. Sufficient Conditions for Efficient Classical Simulation of Quantum Optics

    NASA Astrophysics Data System (ADS)

    Rahimi-Keshari, Saleh; Ralph, Timothy C.; Caves, Carlton M.

    2016-04-01

    We provide general sufficient conditions for the efficient classical simulation of quantum-optics experiments that involve inputting states to a quantum process and making measurements at the output. The first condition is based on the negativity of phase-space quasiprobability distributions (PQDs) of the output state of the process and the output measurements; the second one is based on the negativity of PQDs of the input states, the output measurements, and the transition function associated with the process. We show that these conditions provide useful practical tools for investigating the effects of imperfections in implementations of boson sampling. In particular, we apply our formalism to boson-sampling experiments that use single-photon or spontaneous-parametric-down-conversion sources and on-off photodetectors. Considering simple models for loss and noise, we show that above some threshold for the probability of random counts in the photodetectors, these boson-sampling experiments are classically simulatable. We identify mode mismatching as the major source of error contributing to random counts and suggest that this is the chief challenge for implementations of boson sampling of interesting size.

  14. 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}.

  15. Sufficiently Important Difference for Common Cold: Severity Reduction

    PubMed Central

    Barrett, Bruce; Harahan, Brian; Brown, David; Zhang, Zhengjun; Brown, Roger

    2007-01-01

    PURPOSE We undertook a study to estimate the sufficiently important difference (SID) for the common cold. The SID is the smallest benefit that an intervention would require to justify costs and risks. METHODS Benefit-harm tradeoff interviews (in-person and telephone) assessed SID in terms of overall severity reduction using evidence-based simple-language scenarios for 4 common cold treatments: vitamin C, the herbal medicine echinacea, zinc lozenges, and the unlicensed antiviral pleconaril. RESULTS Response patterns to the 4 scenarios in the telephone and in-person samples were not statistically distinguishable and were merged for most analyses. The scenario based on vitamin C led to a mean SID of 25% (95% confidence interval [CI] 0.23–0.27). For the echinacea-based scenario, mean SID was 32% (95% CI, 0.30–0.34). For the zinc-based scenario, mean SID was 47% (95% CI, 0.43–0.51). The scenario based on preliminary antiviral trials provided a mean SID of 57% (95% CI, 0.53–0.61). Multivariate analyses suggested that (1) between-scenario differences were substantive and reproducible in the 2 samples, (2) presence or severity of illness did not predict SID, and (3) SID was not influenced by age, sex, tobacco use, ethnicity, income, or education. Despite consistencies supporting the model and methods, response patterns were diverse, with wide spreads of individual SID values within and among treatment scenarios. CONCLUSIONS Depending on treatment specifics, people want an on-average 25% to 57% reduction in overall illness severity to justify costs and risks of popular cold treatments. Randomized trial evidence does not support benefits this large. This model and these methods should be further developed for use in other disease entities. PMID:17548849

  16. Low but Sufficient Anidulafungin Exposure in Critically Ill Patients

    PubMed Central

    van Wanrooy, Marjolijn J. P.; Rodgers, Michael G. G.; Uges, Donald R. A.; Arends, Jan P.; Zijlstra, Jan G.; van der Werf, Tjip S.; Kosterink, Jos G. W.

    2014-01-01

    The efficacy of anidulafungin is driven by the area under the concentration-time curve (AUC)/MIC ratio. Patients in intensive care may be at risk for underexposure. In critically ill patients with an invasive Candida infection, the anidulafungin exposure and a possible correlation with disease severity or plasma protein levels were explored. Concentration-time curves were therefore obtained at steady state. Anidulafungin concentrations were measured with a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The MIC values of the Candida species were determined with the Etest. The target AUC/MIC ratio was based on European Committee on Antimicrobial Susceptibility Testing (EUCAST) data. Twenty patients were included. The patients received a maintenance dose of 100 mg once daily after a loading dose of 200 mg on the first day. The mean (±standard deviation) AUC, maximum concentration of drug in plasma (Cmax), and minimum concentration of drug in plasma (Cmin) were 69.8 ± 24.1 mg · h/liter, 4.7 ± 1.4 mg/liter, and 2.2 ± 0.8 mg/liter, respectively. The MIC values of all cultured Candida species were below the EUCAST MIC breakpoints. The exposure to anidulafungin in relation to the MIC that was determined appeared sufficient in all patients. The anidulafungin exposure was low in our critically ill patients. However, combined with the low MICs of the isolated Candida strains, the lower exposure observed in comparison to the exposure in the general patient population resulted in favorable AUC/MIC ratios, based on EUCAST data. No correlation was observed between anidulafungin exposure and disease severity or plasma protein concentrations. In patients with less-susceptible Candida albicans or glabrata strains, we recommend considering determining the anidulafungin exposure to ensure adequate exposure. (This trial has been registered at ClinicalTrials.gov under registration no. NCT01047267.) PMID:24165173

  17. [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.

  18. 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

  19. 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

  20. 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. PMID:11243766

  1. 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.

  2. Point-based rigid registration: clinical validation of theory

    NASA Astrophysics Data System (ADS)

    West, Jay B.; Fitzpatrick, J. Michael

    2000-06-01

    This paper presents the first comparison between theoretical estimates and clinically observed values for registration accuracy in point-based rigid-body registration. Rigid-body registration is appropriate for applications in which relatively rigid parts of the body are involved. In some such applications rigid-body registration is accomplished by aligning two sets of discrete points. In neurosurgical guidance, for example, the points are found by localizing the centroids of fiducial markers. We have previously provided two fundamental theoretical results on the relationship between localization error and registration error in rigid-body, point-based registration and have justified these results by showing them to be close to those given by numerical simulations. Rigid-body, point-based registration is accomplished by finding a rigid-body transformation that aligns pairs of homologous 'fiducial' points. The imprecision in locating a fiducial point is known as the 'fiducial localization error' (FLE). Fiducial points may be centroids of attached markers, which tend to have small, equal FLEs, or salient points in segmented anatomic features, whose FLEs tend to be larger and more varied. Alignment is achieved by minimizing the 'fiducial registration error' (FRE), which is the root mean square distance between homologous fiducials after registration. Closed form solutions for the rigid transformation that minimizes FRE have been known since 1966. A more critical and direct measure of registration error is the 'target registration error' (TRE), which is the distance between homologous points other than the centroids of fiducials. This error measure has been investigated by numerical simulation for many years, and we presented at this meeting in 1998 the first derivation of theoretical estimates of TRE. In that paper we showed that these estimates agree well with our simulations and those of others. We made the simplifying assumption in both the derivations and the

  3. Microfluidic Synthesis of Rigid Nanovesicles for Hydrophilic Reagents Delivery**

    PubMed Central

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

    2015-01-01

    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. PMID:25704675

  4. 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. PMID:26177160

  5. 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.

  6. 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.

  7. New toughening concepts for ceramic composites from rigid natural materials.

    PubMed

    Mayer, George

    2011-07-01

    The mechanisms underlying the toughening in rigid natural composites exhibited by the concentric cylindrical composites of spicules of hexactinellid sponges, and by the nacre (brick-and-mortar) structure of mollusks such as Haliotis rufescens (red abalone), as well as the crossed-lamellar structure of Strombus gigas (queen conch) show commonalities in the manner in which toughening takes place. It is proposed that crack diversion, a new kind of crack bridging, resulting in retardation of delamination, creation of new surface areas, and other energy-dissipating mechanisms occur in both natural systems. However, these are generally different from the toughening mechanisms that are utilized for other classes of structural materials. Complementary to those mechanisms found in rigid natural ceramic/organic composites, special architectures and thin viscoelastic organic layers have been found to play controlling roles in energy dissipation in these structures.

  8. 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.

  9. New toughening concepts for ceramic composites from rigid natural materials.

    PubMed

    Mayer, George

    2011-07-01

    The mechanisms underlying the toughening in rigid natural composites exhibited by the concentric cylindrical composites of spicules of hexactinellid sponges, and by the nacre (brick-and-mortar) structure of mollusks such as Haliotis rufescens (red abalone), as well as the crossed-lamellar structure of Strombus gigas (queen conch) show commonalities in the manner in which toughening takes place. It is proposed that crack diversion, a new kind of crack bridging, resulting in retardation of delamination, creation of new surface areas, and other energy-dissipating mechanisms occur in both natural systems. However, these are generally different from the toughening mechanisms that are utilized for other classes of structural materials. Complementary to those mechanisms found in rigid natural ceramic/organic composites, special architectures and thin viscoelastic organic layers have been found to play controlling roles in energy dissipation in these structures. PMID:21565715

  10. 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.

  11. Packing entropy of extended, hard, rigid objects on a lattice

    NASA Astrophysics Data System (ADS)

    Li, Wenshuo; Freed, Karl F.; Nemirovsky, Adolfo M.

    1993-06-01

    We present a systematic method of evaluating the packing entropy for a set of mutually avoiding extended, hard, rigid objects on a lattice. The method generalizes a simple algebraic representation of the lattice cluster theory developed by Freed and co-workers for systems composed of flexible objects. The theory provides a power series expansion in z-1 for the corrections to the zeroth order mean field approximation partition function, where z is the lattice coordination number. We illustrate the general theory by calculating the packing entropy of four-unit rigid ``square'' objects on a hypercubic lattice as a function of the volume fraction of the squares. As a particular limiting case, we also evaluate for the packing entropy of two, three, and four squares on a two-dimensional square lattice and find agreement with the cluster expansion.

  12. 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.

  13. 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.

  14. High-rigidity Forbush decreases: due to CMEs or shocks?

    NASA Astrophysics Data System (ADS)

    Arunbabu, K. P.; Antia, H. M.; Dugad, S. R.; Gupta, S. K.; Hayashi, Y.; Kawakami, S.; Mohanty, P. K.; Nonaka, T.; Oshima, A.; Subramanian, P.

    2013-07-01

    Aims: We seek to identify the primary agents causing Forbush decreases (FDs) in high-rigidity cosmic rays observed from the Earth. In particular, we ask if these FDs are caused mainly by coronal mass ejections (CMEs) from the Sun that are directed towards the Earth, or by their associated shocks. Methods: We used the muon data at cutoff rigidities ranging from 14 to 24 GV from the GRAPES-3 tracking muon telescope to identify FD events. We selected those FD events that have a reasonably clean profile, and can be reasonably well associated with an Earth-directed CME and its associated shock. We employed two models: one that considers the CME as the sole cause of the FD (the CME-only model) and one that considers the shock as the only agent causing the FD (the shock-only model). We used an extensive set of observationally determined parameters for both models. The only free parameter in these models is the level of MHD turbulence in the sheath region, which mediates cosmic ray diffusion (into the CME for the CME-only model, and across the shock sheath for the shock-only model). Results: We find that good fits to the GRAPES-3 multi-rigidity data using the CME-only model require turbulence levels in the CME sheath region that are only slightly higher than those estimated for the quiescent solar wind. On the other hand, reasonable model fits with the shock-only model require turbulence levels in the sheath region that are an order of magnitude higher than those in the quiet solar wind. Conclusions: This observation naturally leads to the conclusion that the Earth-directed CMEs are the primary contributors to FDs observed in high-rigidity cosmic rays. Appendix A is available in electronic form at http://www.aanda.org

  15. Bending rigid molecular rods: formation of oligoproline macrocycles.

    PubMed

    Scully, Conor C G; Rai, Vishal; Poda, Gennadiy; Zaretsky, Serge; Burns, Darcy C; Houliston, R Scott; Lou, Tiantong; Yudin, Andrei K

    2012-12-01

    Bent but not broken: cyclic oligoprolines are accessed in a reaction that effectively bends rigid oligoproline peptides (see scheme; TBDMS=tert-butyldimethylsilyl). The stitching is accomplished during macrocyclization enabled by aziridine aldehydes and isocyanides. Molecular modeling studies suggest that electrostatic attraction between the termini of the linear peptide is pivotal for macrocyclization. The macrocycles were studied by circular dichroism with a polyproline II structure being observed in larger macrocycles.

  16. Rigidity percolation in dispersions with a structured viscoelastic matrix

    NASA Astrophysics Data System (ADS)

    Wilbrink, M. W. L.; Michels, M. A. J.; Vellinga, W. P.; Meijer, H. E. H.

    2005-03-01

    This paper deals with rigidity percolation in composite materials consisting of a dispersion of mineral particles in a microstructured viscoelastic matrix. The viscoelastic matrix in this specific case is a hydrocarbon refinery residue. In a set of model random composites the mean interparticle surface-to-surface distance was controlled, changing particle volume fraction φ and particle number density independently. This was achieved by mixing two sets of monodisperse particles with widely differing radii ( 0.35μm and 17.5μm ) with the matrix. A scaling exponent of 3.9±0.6 for the storage modulus G' vs φ-φc was observed above a threshold φc , in good agreement with theoretical values for rigidity percolation. It is found that at the rigidity-percolation threshold the pore structure, as characterized by the mean surface-to-surface distance for the filler, rather than the filler volume fraction, is similar for different types of composites. This behavior is explained from the internal structure of the viscoelastic matrix, which consists of fractal solid aggregates dissolved in a viscous medium; the effective radius of these aggregates and the mean surface-to-surface distance together determine whether or not the aggregates are capable of providing rigidity to the composite. The explanation is further supported by a qualitative comparison with effective-medium calculations. These indicate that the observed breakdown of time-temperature superposition near φc is due to the appearance of a time scale characteristic for the mechanical interplay between the viscous binder phase and the purely elastic solid particles.

  17. 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.

  18. 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.

  19. 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.

  20. Stabilization of the permanent rotations of a rigid body

    NASA Astrophysics Data System (ADS)

    Biiarov, T.; Krementulo, V. V.; Tazhekov, A.

    1991-08-01

    The problem of stabilization of the equilibrium and permanent rotations of a heavy rigid body with a fixed point is solved in the classical cases of Euler, Lagrange, and Kovalevskaya using methods of analytical control theory. In the above cases, the control moments obtained in explicit form provide for the asymptotic stability of the permanent rotation on the whole. The control moments are selected in the form of linear functions with respect to perturbations.

  1. 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.

  2. Dielectric elastomer bending tube actuators with rigid electrode structures

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  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. Rigid facial motion influences featural, but not holistic, face processing.

    PubMed

    Xiao, Naiqi G; Quinn, Paul C; Ge, Liezhong; Lee, Kang

    2012-03-15

    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 1-3, 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/foil 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 1-3, 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.

  5. 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.

  6. Rigidity based formation tracking for multi-agent networks

    NASA Astrophysics Data System (ADS)

    Bai, Lu; Chen, Fei; Lan, Wei-Yao

    2015-09-01

    This paper considers the formation tracking problem under a rigidity framework, where the target formation is specified as a minimally and infinitesimally rigid formation and the desired velocity of the group is available to only a subset of the agents. The following two cases are considered: the desired velocity is constant, and the desired velocity is time-varying. In the first case, a distributed linear estimator is constructed for each agent to estimate the desired velocity. The velocity estimation and a formation acquisition term are employed to design the control inputs for the agents, where the rigidity matrix plays a central role. In the second case, a distributed non-smooth estimator is constructed to estimate the time-varying velocity, which is shown to converge in a finite time. Theoretical analysis shows that the formation tracking problem can be solved under the proposed control algorithms and estimators. Simulation results are also provided to show the validity of the derived results. Project supported by the National Natural Science Foundation of China (Grant No. 61473240).

  7. Rigid facial motion influences featural, but not holistic, face processing.

    PubMed

    Xiao, Naiqi G; Quinn, Paul C; Ge, Liezhong; Lee, Kang

    2012-03-15

    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 1-3, 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/foil 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 1-3, 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

  8. 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.

  9. Measuring membrane rigidity and viscosity: New methods, and new insights

    NASA Astrophysics Data System (ADS)

    Parthasarathy, Raghuveer

    2014-03-01

    Lipid membranes are remarkable materials: flexible, two-dimensional fluids whose physical properties guide cellular function. Bending rigidity and viscosity are two of the key mechanical parameters that characterize membranes. Both, however, are challenging to measure. I describe improvements in experimental techniques to quantify the bending modulus and the two-dimensional viscosity of lipid membranes. First, I show that using selective plane illumination microscopy (SPIM, also known as light sheet fluorescence microscopy) to image the thermal fluctuations of freely suspended giant lipid vesicles enables straightforward measurements of membrane rigidity, and also provides insights into changes in rigidity induced by cargo trafficking proteins. Second, I show that tracking both the rotational and translational diffusion of membrane-anchored tracer particles allows quantification of membrane viscosity, measurement of the effective radii of the tracers, and assessment of theoretical models of membrane hydrodynamics. Surprisingly, we find a wide distribution of effective tracer sizes, due presumably to a wide variety of couplings to the membrane. I also provide an example of protein-mediated changes in lipid viscosity.

  10. 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.

  11. 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.

  12. 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. PMID:27046840

  13. New Langevin and gradient thermostats for rigid body dynamics

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    PubMed

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

    2015-04-14

    We introduce two new thermostats, one of Langevin type and one of gradient (Brownian) type, for rigid body dynamics. We formulate rotation using the quaternion representation of angular coordinates; both thermostats preserve the unit length of quaternions. The Langevin thermostat also ensures that the conjugate angular momenta stay within the tangent space of the quaternion coordinates, as required by the Hamiltonian dynamics of rigid bodies. We have constructed three geometric numerical integrators for the Langevin thermostat and one for the gradient thermostat. The numerical integrators reflect key properties of the thermostats themselves. Namely, they all preserve the unit length of quaternions, automatically, without the need of a projection onto the unit sphere. The Langevin integrators also ensure that the angular momenta remain within the tangent space of the quaternion coordinates. The Langevin integrators are quasi-symplectic and of weak order two. The numerical method for the gradient thermostat is of weak order one. Its construction exploits ideas of Lie-group type integrators for differential equations on manifolds. We numerically compare the discretization errors of the Langevin integrators, as well as the efficiency of the gradient integrator compared to the Langevin ones when used in the simulation of rigid TIP4P water model with smoothly truncated electrostatic interactions. We observe that the gradient integrator is computationally less efficient than the Langevin integrators. We also compare the relative accuracy of the Langevin integrators in evaluating various static quantities and give recommendations as to the choice of an appropriate integrator. PMID:25877569

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

    PubMed

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

    2015-04-14

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

  16. 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.

  17. A rigid and weathered ice shell on Titan.

    PubMed

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

    2013-08-29

    Several lines of evidence suggest that Saturn's largest moon, Titan, has a global subsurface ocean beneath an outer ice shell 50 to 200 kilometres thick. If convection is occurring, the rigid portion of the shell is expected to be thin; similarly, a weak, isostatically compensated shell has been proposed to explain the observed topography. Here we report a strong inverse correlation between gravity and topography at long wavelengths that are not dominated by tides and rotation. We argue that negative gravity anomalies (mass deficits) produced by crustal thickening at the base of the ice shell overwhelm positive gravity anomalies (mass excesses) produced by the small surface topography, giving rise to this inverse correlation. We show that this situation requires a substantially rigid ice shell with an elastic thickness exceeding 40 kilometres, and hundreds of metres of surface erosion and deposition, consistent with recent estimates from local features. Our results are therefore not compatible with a geologically active, low-rigidity ice shell. After extrapolating to wavelengths that are controlled by tides and rotation, we suggest that Titan's moment of inertia may be even higher (that is, Titan may be even less centrally condensed) than is currently thought. PMID:23985871

  18. Coarse-grained rigid blob model for soft matter simulations

    NASA Astrophysics Data System (ADS)

    Chao, Sheng D.; Kress, Joel D.; Redondo, Antonio

    2005-06-01

    We have developed a coarse-grained multiscale molecular simulation method for soft matter systems that directly incorporates stereochemical information. We divide the material into disjoint groups of atoms or particles that move as separate rigid bodies; we call these groups "rigid blobs," hence the name coarse-grained rigid blob model. The method is enabled by the construction of transferable interblob potentials that approximate the net intermolecular interactions, as obtained from ab initio electronic structure calculations, other all-atom empirical potentials, experimental data, or any combination of the above. We utilize a multipolar expansion to obtain the interblob potential-energy functions. The series, which contains controllable approximations that allow us to estimate the errors, approaches the original intermolecular potential as the number of terms increases. Using a novel numerical algorithm, we can calculate the interblob potentials very efficiently in terms of a few interaction moment tensors. This reduces the labor well beyond what is required in standard molecular-dynamics calculations and allows large-scale simulations for temporal scales commensurate with characteristic times of nano- and mesoscale systems. A detailed derivation of the formulas is presented, followed by illustrative applications to several systems showing that the method can effectively capture realistic microscopic details and can easily extend to large-scale simulations.

  19. 49 CFR 178.925 - Standards for rigid plastic Large Packagings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

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

  20. 49 CFR 178.925 - Standards for rigid plastic Large Packagings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

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

  1. 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...

  2. Multiscale multiphysics and multidomain models—Flexibility and rigidity

    SciTech Connect

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

    2013-11-21

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

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

    PubMed

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

    2015-06-01

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

  4. Direct numerical simulation of rigid bodies in multiphase flow within an Eulerian framework

    NASA Astrophysics Data System (ADS)

    Rauschenberger, P.; Weigand, B.

    2015-06-01

    A new method is presented to simulate rigid body motion in the Volume-of-Fluid based multiphase code Free Surface 3D. The specific feature of the new method is that it works within an Eulerian framework without the need for a Lagrangian representation of rigid bodies. Several test cases are shown to prove the validity of the numerical scheme. The technique is able to conserve the shape of arbitrarily shaped rigid bodies and predict terminal velocities of rigid spheres. The instability of a falling ellipsoid is captured. Multiple rigid bodies including collisions may be considered using only one Volume-of-Fluid variable which allows to simulate the drafting, kissing and tumbling phenomena of two rigid spheres. The method can easily be extended to rigid bodies undergoing phase change processes.

  5. Nonlinear dynamic behavior of microscopic bubbles near a rigid wall

    NASA Astrophysics Data System (ADS)

    Suslov, Sergey A.; Ooi, Andrew; Manasseh, Richard

    2012-06-01

    The nonlinear dynamic behavior of microscopic bubbles near a rigid wall is investigated. Oscillations are driven by the ultrasonic pressure field that arises in various biomedical applications such as ultrasound imaging or targeted drug delivery. It is known that, when bubbles approach a blood-vessel wall, their linear dynamic response is modified. This modification may be very useful for real-time detection of bubbles that have found targets; in future therapeutic technologies, it may be useful for controlled release of medical agents encapsulating microbubbles. In this paper, the nonlinear response of microbubbles near a wall is studied. The Keller-Miksis-Parlitz equation is adopted, but modified to account for the presence of a rigid wall. This base model describes the time evolution of the bubble surface, which is assumed to remain spherical, and accounts for the effect of acoustic radiation losses owing to liquid compressibility in the momentum conservation. Two situations are considered: the base case of an isolated bubble in an unbounded medium, and a bubble near a rigid wall. In the latter case, the wall influence is modeled by including a symmetrically oscillating image bubble. The bubble dynamics is traced using a numerical solution of the model equation. Subsequently, Floquet theory is used to accurately detect the bifurcation point where bubble oscillations stop following the driving ultrasound frequency and undergo period-changing bifurcations. Of particular interest is the detection of the subcritical period-tripling and -quadrupling transition. The parametric bifurcation maps are obtained as functions of nondimensional parameters representing the bubble radius, the frequency and pressure amplitude of the driving ultrasound field, and the distance from the wall. It is shown that the presence of the wall generally stabilises the bubble dynamics, so that much larger values of the pressure amplitude are needed to generate nonlinear responses. Thus, a

  6. Simplified seismic fatigue evaluation for rigid steel connections

    NASA Astrophysics Data System (ADS)

    Shama, Ayman A.; Mander, John B.; Chen, Stuart S.

    2003-12-01

    A simplified fatigue-life model is proposed for assessing the seismic inelastic rotational capacity of steel connections. First relations are developed for rigid steel connections under lateral loading. Next this is extended to account for the effects of the welded steel moment frame (WSMF) connections of the so-called pre-Northridge type. The seismic fatigue theory is validated against experimental results. The experiments were conducted under increasing ductility amplitudes until the onset of fracture. Miner’ rule was used to convert the test results to given an equivalent constant amplitude cyclic fatigue life. Satisfactory agreement is obtained when comparing the experimental observations with the theoretical predictions.

  7. The free rigid body dynamics: Generalized versus classic

    NASA Astrophysics Data System (ADS)

    Tudoran, Rǎzvan M.

    2013-07-01

    In this paper we analyze some normal forms of a general quadratic Hamiltonian system defined on the dual of the Lie algebra {o}(K) of real K-skew-symmetric matrices, where K is an arbitrary 3×3 real symmetric matrix. A consequence of the main results is that any first-order autonomous three-dimensional differential equation possessing two independent quadratic constants of motion, which admit a positive/negative definite linear combination, is affinely equivalent to the classical "relaxed" free rigid body dynamics with linear control parameters.

  8. Masseter muscle rigidity: Atypical malignant hyperthermia presentation or isolated event?

    PubMed

    Onyeka, Tonia C U

    2010-09-01

    This report describes a case of masseter muscle rigidity encountered at the start of an elective gynaecological procedure. At preoperative assessment, the patient, a 41-year old woman with a previous non-eventful surgical and anesthetic history was given a Mallampati score of 3. Following suxamethonium administration, full mouth opening proved difficult. Laryngoscopy and tracheal intubation were not possible leading to the eventual use of a laryngeal mask airway and resulting in a successful anaesthetic outcome. A number of possibilities that may account for this situation as well as viable options for airway access in such cases are discussed below. PMID:21189861

  9. Ball Semi-Rigid Advanced Mirror System Demonstrator (AMSD)

    NASA Technical Reports Server (NTRS)

    Kendrick, Stephen; Russell, Kevin (Technical Monitor)

    2001-01-01

    The AMSD Program is to design, fabricate, and test a 1.4-m point-to-point hexagon mirror system. The Ball semi-rigid approach will be described and its current status presented, The mirror system includes a lightweighted beryllium mirror that is attached through flexures and actuators to a composite reaction structure enabling optical performance at ambient and cryogenic temperatures and allowing changes of curvature to be imposed via actuation. This program is administered through NASA MSFC and is jointly funded by NASA, the USAF, and the NRO.

  10. Modelling hanging wall accommodation above rigid thrust ramps

    NASA Astrophysics Data System (ADS)

    Bonini, Marco; Sokoutis, Dimitrios; Mulugeta, Genene; Katrivanos, Emmanouil

    2000-08-01

    Experimental models are used to study the role of material rheology in hanging wall accommodation above rigid flat-ramp-flat thrust footwalls. The deformation in the hanging wall was accomplished by forwards sliding along a rigid basal staircase trajectory with a variable ramp angle, α, ranging from 15° to 60°. We model different ramp angles to examine hanging wall accommodation styles above thrust ramps of overthrust faults ( α ranging from 15° to 30°), as well as above pre-existing normal faults ( α ranging from 45° to 60°). For the hanging walls we used stratified frictional (sand) and viscous (silicone putty) materials. In this paper we study three types of models. Type 1 models represent purely frictional hanging walls where accommodation above thrust ramps was by layer-parallel thickening and by generating a series of back thrusts. Type 2 and 3 models represent stratified frictional/viscous hanging walls. In these models, accommodation was by a complex association of reverse and normal faults, mainly controlled by the rheological anisotropy as well as by the ramp inclination angle α. In Type 2 models the silicone covered only the lower flat, while in Type 3 models it also covered the rigid ramp. For α≤30° in Type 2 models and α≤45° in Type 3 models, the viscous layer inhibited the development of back thrusts in the frictional hanging wall, instead the silicone thickened to develop a 'ductile ramp'. For α-values higher than 30° in Type 2 models and α=45° in Type 3 models, back thrusts develop in response to the bulk compression. The experiments simulate many structures observed above natural thrust ramps with α≤30° and pre-existing normal faults with α≥45°. The models emphasise the importance of a basal ductile layer, which allows the hanging wall to step-up over the rigid ramp by building up its own ductile ramp. The models also emphasise that foreland-directed normal faulting can develop at a thrust front in the case that the

  11. The market for large rigid haul trucks in surface mining

    SciTech Connect

    Gilewicz, P.

    2002-04-15

    Originally published in 2001 this updated report provides a definition of the market for large rigid haulers in surface mining. The analysis covers changes to the mining market segments buying these machines including the gains made by coal producers, retrenchment in copper mining, the consolidation taking place among gold mining companies, and the expansion of iron ore producers in Australia and Brazil. It includes a detailed accounting of 2001 truck shipments, and an analysis of trends in the Ultra-truck segment. It concludes with a revised forecast for shipments through 2006. 12 charts, 56 tabs., 2 apps.

  12. Towards understanding elastocapillarity: comparing wetting of soft and rigid plates.

    PubMed

    Ji, Xiang-Ying; Feng, Xi-Qiao

    2014-04-16

    Elastocapillarity plays a significant role in the buoyancy and water repellency of soft objects floating on water. In this paper, we analyze the wetting behavior of an elastic and circular plate pressing a liquid surface. The geometry and stability of axisymmetric infinite liquid menisci are investigated, and their qualitative difference from two-dimensional planar menisci is revealed. By comparing the wetting processes of rigid and elastic circular plates under pressing, we show that flexibility benefits both the maximal depth and buoyancy a plate can reach. The results are helpful not only for understanding the living behavior of some aquatic creatures but also for the design of biomimetic soft microrobotics.

  13. ENERGETIC PARTICLE ANISOTROPIES AT THE HELIOSPHERIC BOUNDARY. II. TRANSIENT FEATURES AND RIGIDITY DEPENDENCE

    SciTech Connect

    Florinski, V.; Roux, J. A. le; Stone, E. C.; Cummings, A. C.

    2015-04-10

    In the preceding paper, we showed that large second-order anisotropies of heliospheric ions measured by the Voyager 1 space probe during the August 2012 boundary crossing event could be explained by a magnetic shear across the heliopause preventing particles streaming along the magnetic field from escaping the inner heliosheath. According to Stone et al., the penetration distance of heliospheric ions into the outer heliosheath had a strong dependence on the particle’s Larmor radius. By comparing hydrogen, helium, and oxygen ions with the same energy per nucleon, these authors argued that this effect must be attributed to larger cyclotron radii of heavier species rather than differences in velocity. We propose that gradient drift in a nonuniform magnetic field was the cause of both the large second-order anisotropies and the spatial differentiation based on the ion’s rigidity. A latitudinal gradient of magnetic field strength of about 10% per AU between 2012.7 and 2012.9 could have provided drift motion sufficient to match both LECP and CRS Voyager 1 observations. We explain the transient intensity dropout observed prior to the heliocliff using flux tube structures embedded in the heliosheath and magnetically connected to interstellar space. Finally, this paper reports a new indirect measurement of the plasma radial velocity at the heliopause on the basis of the time difference between two cosmic-ray telescopes measuring the same intensity dropout.

  14. High temperature testing of TRUPACT-I materials: Kevlar, honeycomb, rigid polyurethane foam

    SciTech Connect

    Hudson, M.L.

    1985-12-01

    When the Transuranic Package Transporter Model-I (TRUPACT-I) failed to afford sufficient containment after a 35-minute JP-4 fueled open-pool fire, component tests were conducted, in conjunction with analyses, to guide and assess the redesign of TRUPACT-I. Since materials which change phase or combust are difficult to numerically analyze, the component tests determined the behavior of these materials in TRUPACT-I. The component tests approximated the behavior of Kevlar (registered trademark of DuPont), metal honeycomb, and rigid polyurethane foam, as they appear in TRUPACT-I, in an open-pool fire environment. Six series of tests were performed at Sandia's Radiant Heat Facility and one test at the wind-shielded fire test facility (LAARC Chimney). Each test facility was controlled to yield temperatures or heat fluxes equivalent to those measured in the TRUPACT-I, Unit 0, open-pool fire. This extensive series of component tests (34 runs total) provided information on the high-temperature behavior of unique materials which was not previously available or otherwise attainable. The component tests were a timely and cost-effective means of providing the data for the TRUPACT-I redesign.

  15. Polymer glass transition occurs at the marginal rigidity point with connectivity z* = 4.

    PubMed

    Lappala, Anna; Zaccone, Alessio; Terentjev, Eugene M

    2016-09-21

    We re-examine the physical origin of the polymer glass transition from the point of view of marginal rigidity, which is achieved at a certain average number of mechanically active intermolecular contacts per monomer. In the case of polymer chains in a melt/poor solvent, each monomer has two neighbors bound by covalent bonds and also a number of central-force contacts modelled by the Lennard-Jones (LJ) potential. We find that when the average number of contacts per monomer (covalent and non-covalent) exceeds the critical value z* ≈ 4, the system becomes solid and the dynamics arrested - a state that we declare the glass. Coarse-grained Brownian dynamics simulations show that at sufficient strength of LJ attraction (which effectively represents the depth of quenching, or the quality of solvent) the polymer globule indeed crosses the threshold of z*, and becomes a glass with a finite zero-frequency shear modulus, G∝ (z-z*). We verify this by showing the distinction between the 'liquid' polymer droplet at z < z*, which changes shape and adopts the spherical conformation in equilibrium, and the glassy 'solid' droplet at z > z*, which retains its shape frozen at the moment of z* crossover. These results provide a robust microscopic criterion to tell the liquid apart from the glass for the linear polymers. PMID:27517325

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  17. A molecular dynamics study of the failure modes of a glassy polymer confined between rigid walls

    NASA Astrophysics Data System (ADS)

    Kulmi, Udit; Basu, Sumit

    2006-09-01

    Adhesion is a complex and multifaceted phenomenon which is controlled by various factors such as the loading rate, interface toughness, temperature and geometric and molecular properties. The mode of failure of adhesive joints (adhesive or cohesive) is decided through a complex interplay between these factors. In this work, we study the failure under tensile loading of a thin layer of a polymeric material confined between two rigid walls using molecular dynamics simulations. The strength of the interface is controlled by the interaction potential between the polymer and wall atoms. The polymer modelled is a simple linear chain of 'united atoms' having a fixed bond length but contributions to the energy arise from bending and torsion of bonds as well as from non-bonded interactions between the 'united atoms'. The results indicate that even when the adhesion between the wall and the polymer is weak, a short chained polymer is more likely to fail by a mixed adhesive cohesive mode. A long chained polymer, with the same interface strength, fails in a pure adhesive manner. However, when the interface is sufficiently strengthened, the long chained polymer fails cohesively and it can bear a much higher load. The failure mode is somewhat modulated by the rate at which deformation occurs. Moreover, when the polymer is confined such that the spacing between the walls is comparable to the end-to-end distance of the polymer chain, strength of the joint increases significantly. In such a situation, even polymers with weak interfacial adhesion might fail cohesively.

  18. Maximum-likelihood estimation of lithospheric flexural rigidity, initial-loading fraction and load correlation, under isotropy

    NASA Astrophysics Data System (ADS)

    Simons, Frederik J.; Olhede, Sofia C.

    2013-06-01

    Topography and gravity are geophysical fields whose joint statistical structure derives from interface-loading processes modulated by the underlying mechanics of isostatic and flexural compensation in the shallow lithosphere. Under this dual statistical-mechanistic viewpoint an estimation problem can be formulated where the knowns are topography and gravity and the principal unknown the elastic flexural rigidity of the lithosphere. In the guise of an equivalent `effective elastic thickness', this important, geographically varying, structural parameter has been the subject of many interpretative studies, but precisely how well it is known or how best it can be found from the data, abundant nonetheless, has remained contentious and unresolved throughout the last few decades of dedicated study. The popular methods whereby admittance or coherence, both spectral measures of the relation between gravity and topography, are inverted for the flexural rigidity, have revealed themselves to have insufficient power to independently constrain both it and the additional unknown initial-loading fraction and load-correlation factors, respectively. Solving this extremely ill-posed inversion problem leads to non-uniqueness and is further complicated by practical considerations such as the choice of regularizing data tapers to render the analysis sufficiently selective both in the spatial and spectral domains. Here, we rewrite the problem in a form amenable to maximum-likelihood estimation theory, which we show yields unbiased, minimum-variance estimates of flexural rigidity, initial-loading fraction and load correlation, each of those separably resolved with little a posteriori correlation between their estimates. We are also able to separately characterize the isotropic spectral shape of the initial-loading processes. Our procedure is well-posed and computationally tractable for the two-interface case. The resulting algorithm is validated by extensive simulations whose behaviour is

  19. 76 FR 39115 - Notice of Proposed Information Collection: Transformation Initiative Family Self-Sufficiency...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-05

    ... Family Self-Sufficiency Demonstration Small Grants. Description of the need for information and proposed... URBAN DEVELOPMENT Notice of Proposed Information Collection: Transformation Initiative Family Self-Sufficiency Demonstration Small Grants AGENCY: Office of Policy Development and Research, HUD. ACTION:...

  20. [A new approach to arterial rigidity: ultrasonic tissue mode imaging].

    PubMed

    Steinbach, J C; Saboya, M I; Le Bourg, F; Petit, H; Gény, B; Stephan, D

    2003-01-01

    Vascular stiffness is a major contributory factor of cardiovascular morbidity and mortality. Tissue Doppler imaging (TDI) could make it possible to evaluate vascular rigidity in a site by the measurement of the arterial wall velocity. The objective of this work is to validate the use of tissue Doppler imaging in the assessment of carotid rigidity. The following parameters were measured with TDI (ATL HDI 5000 and software HDI Lab): maximum velocity and mean acceleration of parietal motion (VMax and AccMax). These measurements were corrected for the arterial diameter and pulse pressure (VMax cor and AccMax cor). These data have been compared to the calculated parameters of elasticity from a mode M echography. Thirty-one subjects aged of 26 to 77 years (41.6 +/- 10.6 years, m +/- ESM), without atheromatous plaque or high blood pressure, have been included. The VMax is correlated very significantly at the parietal velocity calculated with mode M echography (r = 0.77; p = 0.00002). The VMax cor is correlated significantly with the parameters of stiffness following: distensibility coefficient, compliance coefficient, pulse wave velocity, elasticity modulus of Young, coefficient beta. [table: see text] Tissue Doppler imaging allows an easy evaluation of the carotid stiffness correlated with the parameters of elasticity. Therefore it constitutes a method of evaluation of the cardiovascular risk. Further longitudinal studies will be able to assess the involvement of the carotid stiffness as causal agent of the cardiovascular risk.

  1. Plane stress problems using hysteretic rigid body spring network models

    NASA Astrophysics Data System (ADS)

    Christos, Sofianos D.; Vlasis, Koumousis K.

    2016-08-01

    In this work, a discrete numerical scheme is presented capable of modeling the hysteretic behavior of 2D structures. Rigid Body Spring Network (RBSN) models that were first proposed by Kawai (Nucl Eng Des 48(1):29-207, 1978) are extended to account for hysteretic elastoplastic behavior. Discretization is based on Voronoi tessellation, as proposed specifically for RBSN models to ensure uniformity. As a result, the structure is discretized into convex polygons that form the discrete rigid bodies of the model. These are connected with three zero length, i.e., single-node springs in the middle of their common facets. The springs follow the smooth hysteretic Bouc-Wen model which efficiently incorporates classical plasticity with no direct reference to a yield surface. Numerical results for both static and dynamic loadings are presented, which validate the proposed simplified spring-mass formulation. In addition, they verify the model's applicability on determining primarily the displacement field and plastic zones compared to the standard elastoplastic finite element method.

  2. Supramolecular barrels from amphiphilic rigid-flexible macrocycles.

    PubMed

    Yang, Won-Young; Ahn, Jong-Hyun; Yoo, Yong-Sik; Oh, Nam-Keun; Lee, Myongsoo

    2005-05-01

    Precise control of supramolecular objects requires the rational design of molecular components, because the information determining their specific assembly should be encoded in their molecular architecture. In this context, diverse self-assembling molecules including liquid crystals, dendrimers, block copolymers, hydrogen-bonded complexes and rigid macrocycles are being created as a means of manipulating supramolecular structure. Incorporation of a stiff rod-like building block into an amphiphilic molecular architecture leads to another class of self-assembling molecules. Aggregation of rod building blocks can generate various nanoscale objects including bundles, ribbons, tubules and vesicles, depending on the molecular structure and/or the presence of a selective solvent. We present here an unusual example of supramolecular barrels in the solid and in aqueous solution, based on the self-assembly of amphiphilic rigid-flexible macrocycles driven by non-covalent interactions. Preliminary experiments show that these amphiphilic macrocycles are membrane-active. The amphiphilic macrocycles might thus lead to an excellent model system for exploring biological processes in supramolecular materials.

  3. Synthesis of rigid p-terphenyl-linked carbohydrate mimetics

    PubMed Central

    Kandziora, Maja

    2014-01-01

    Summary An approach to β-D-2-aminotalose- and β-D-2-aminoidose-configured carbohydrate mimetics bearing a phenyl substituent is described. Unnatural divalent rigid p-terphenyl-linked C-aryl glycosides with 2.0 nm dimension are available using Suzuki cross-couplings. The key compound, a p-bromophenyl-substituted 1,2-oxazine, was prepared by a stereoselective [3 + 3]-cyclization of a D-isoascorbic acid-derived (Z)-nitrone and lithiated TMSE-allene. The Lewis acid-induced rearrangement of this heterocycle provided the corresponding bicyclic 1,2-oxazine derivative that may be regarded as internally protected amino sugar analogue. After subsequent reduction of the carbonyl group, the resulting bicyclic compound was used for Suzuki cross-couplings to form biphenyl aminopyran or p-terphenyl-linked dimers. Hydrogenolysis afforded new unnatural aminosugar mimetics. Zinc in the presence of acid or samarium diiodide were examined for the N–O bond cleavage in order to obtain the rigid p-terphenyl-linked C-glycosyl dimers. PMID:25161733

  4. Rigid Cooperation of Per1 and Per2 proteins

    NASA Astrophysics Data System (ADS)

    Tamiya, Hiroyuki; Ogawa, Sumito; Ouchi, Yasuyoshi; Akishita, Masahiro

    2016-09-01

    Period circadian clock (Per) genes Per1 and Per2 have essential roles in circadian oscillation. In this study, we identified a new role of Per1-Per2 cooperation, and its mechanism, using our new experimental methods. Under constant light conditions, the period length of Per1 and Per2 knockout mice depended on the copy number ratio of Per1:Per2. We then established a light-emitting diode-based lighting system that can generate any pattern of light intensity. Under gradually changing light in the absence of phase shift with different periods, both Per1(‑/‑) and Per2(‑/‑) mice were entrained to a broader range of period length than wild-type mice. To analyse Per1-Per2 cooperative roles at the cell culture level, we established a Per2 knockout-rescue system, which can detect period shortening in a familial advanced sleep phase syndrome (FASPS) mutant. Upon introduction of the Per1 coding region in this system, we saw period shortening. In conclusion, short period-associated protein Per1 and long period-associated Per2 cooperated to rigidly confine the circadian period to “circa” 24-h. These results suggest that the rigid circadian rhythm maintained through the cooperation of Per1-Per2 could negatively impact modern society, in which the use of artificial lighting is ubiquitous, and result in circadian disorders, including delirium.

  5. Rigid Cooperation of Per1 and Per2 proteins.

    PubMed

    Tamiya, Hiroyuki; Ogawa, Sumito; Ouchi, Yasuyoshi; Akishita, Masahiro

    2016-01-01

    Period circadian clock (Per) genes Per1 and Per2 have essential roles in circadian oscillation. In this study, we identified a new role of Per1-Per2 cooperation, and its mechanism, using our new experimental methods. Under constant light conditions, the period length of Per1 and Per2 knockout mice depended on the copy number ratio of Per1:Per2. We then established a light-emitting diode-based lighting system that can generate any pattern of light intensity. Under gradually changing light in the absence of phase shift with different periods, both Per1((-/-)) and Per2((-/-)) mice were entrained to a broader range of period length than wild-type mice. To analyse Per1-Per2 cooperative roles at the cell culture level, we established a Per2 knockout-rescue system, which can detect period shortening in a familial advanced sleep phase syndrome (FASPS) mutant. Upon introduction of the Per1 coding region in this system, we saw period shortening. In conclusion, short period-associated protein Per1 and long period-associated Per2 cooperated to rigidly confine the circadian period to "circa" 24-h. These results suggest that the rigid circadian rhythm maintained through the cooperation of Per1-Per2 could negatively impact modern society, in which the use of artificial lighting is ubiquitous, and result in circadian disorders, including delirium.

  6. Normalized inverse characterization of sound absorbing rigid porous media.

    PubMed

    Zieliński, Tomasz G

    2015-06-01

    This paper presents a methodology for the inverse characterization of sound absorbing rigid porous media, based on standard measurements of the surface acoustic impedance of a porous sample. The model parameters need to be normalized to have a robust identification procedure which fits the model-predicted impedance curves with the measured ones. Such a normalization provides a substitute set of dimensionless (normalized) parameters unambiguously related to the original model parameters. Moreover, two scaling frequencies are introduced, however, they are not additional parameters and for different, yet reasonable, assumptions of their values, the identification procedure should eventually lead to the same solution. The proposed identification technique uses measured and computed impedance curves for a porous sample not only in the standard configuration, that is, set to the rigid termination piston in an impedance tube, but also with air gaps of known thicknesses between the sample and the piston. Therefore, all necessary analytical formulas for sound propagation in double-layered media are provided. The methodology is illustrated by one numerical test and by two examples based on the experimental measurements of the acoustic impedance and absorption of porous ceramic samples of different thicknesses and a sample of polyurethane foam. PMID:26093413

  7. Origami-Inspired Folding of Thick, Rigid Panels

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  8. Using "Rebar" to Stabilize Rigid Chest Wall Reconstruction.

    PubMed

    Robinson, Lary A; Grubbs, Deanna M

    2016-04-01

    After major chest wall resection, reconstruction of the bony defect with a rigid prosthesis is mandatory to protect the underlying thoracic organs, and to prevent flail chest physiology. Although many methods have been described for chest wall reconstruction, a commonly used technique employs a composite Marlex (polypropylene) mesh with methyl-methacrylate cement sandwiched between two layers of mesh (MMS), which is tailored to the defect size and shape. In building construction, steel "rebar" is used to strengthen and reinforce masonry structures. To avoid the initial residual motion of the rigid prosthesis used to reconstruct very large defects, particularly the sternum, we devised a simple technique of adding one or more Steinmann steel pins as "rebar" to strengthen and immediately stabilize the prosthesis to the surrounding ribs and sternum. For the very large defects, particularly over the heart and great vessels, titanium mesh may also be readily added into the sandwich construction for increased strength and to prevent late prosthetic fractures. Short- and long-term results of this inexpensive modification of the MMS reconstruction technique are excellent. This modified MMS tailor-made prosthesis is only one-third the cost of the recently popular prosthetic titanium systems, takes much less operative time to create and implant, and avoids the well-described complications of late titanium bar fracture and erosion/infection as well as loosening of screws and/or titanium bars.

  9. Awake craniotomy using electromagnetic navigation technology without rigid pin fixation.

    PubMed

    Morsy, Ahmed A; Ng, Wai Hoe

    2015-11-01

    We report our institutional experience using an electromagnetic navigation system, without rigid head fixation, for awake craniotomy patients. The StealthStation® S7 AxiEM™ navigation system (Medtronic, Inc.) was used for this technique. Detailed preoperative clinical and neuropsychological evaluations, patient education and contrast-enhanced MRI (thickness 1.5mm) were performed for each patient. The AxiEM Mobile Emitter was typically placed in a holder, which was mounted to the operating room table, and a non-invasive patient tracker was used as the patient reference device. A monitored conscious sedation technique was used in all awake craniotomy patients, and the AxiEM Navigation Pointer was used for navigation during the procedure. This offers the same accuracy as optical navigation, but without head pin fixation or interference with intraoperative neurophysiological techniques and surgical instruments. The application of the electromagnetic neuronavigation technology without rigid head fixation during an awake craniotomy is accurate, and offers superior patient comfort. It is recommended as an effective adjunctive technique for the conduct of awake surgery.

  10. Rigidity transition in polymer melts with van der Waals interaction.

    PubMed

    Wallace, Matthew L; Joós, Béla; Plischke, Michael

    2004-10-01

    We study the onset of rigidity near the glass transition (GT) in a short-chain polymer melt modelled by a bead-spring model, where all beads interact with Lennard-Jones potentials. The properties of the system are examined above and below the GT. In order to minimize high-cooling-rate effects and computational times, equilibrium configurations are reached via isothermal compression. We monitor quantities such as the heat capacity CP, the short-time diffusion constants D, the viscosity eta , and the shear modulus; the time-dependent shear modulus Gt is compared with the shear modulus mu obtained from an externally applied instantaneous shear. We give a detailed analysis of the effects of such shearing on the system, both locally and globally. It is found that the polymeric glass displays long-time rigid behavior only below a temperature T1 , where T1 < TG. Furthermore, the linear and nonlinear relaxation regimes under applied shear are discussed. PMID:15600413

  11. Rigid Cooperation of Per1 and Per2 proteins

    PubMed Central

    Tamiya, Hiroyuki; Ogawa, Sumito; Ouchi, Yasuyoshi; Akishita, Masahiro

    2016-01-01

    Period circadian clock (Per) genes Per1 and Per2 have essential roles in circadian oscillation. In this study, we identified a new role of Per1-Per2 cooperation, and its mechanism, using our new experimental methods. Under constant light conditions, the period length of Per1 and Per2 knockout mice depended on the copy number ratio of Per1:Per2. We then established a light-emitting diode-based lighting system that can generate any pattern of light intensity. Under gradually changing light in the absence of phase shift with different periods, both Per1(−/−) and Per2(−/−) mice were entrained to a broader range of period length than wild-type mice. To analyse Per1-Per2 cooperative roles at the cell culture level, we established a Per2 knockout-rescue system, which can detect period shortening in a familial advanced sleep phase syndrome (FASPS) mutant. Upon introduction of the Per1 coding region in this system, we saw period shortening. In conclusion, short period-associated protein Per1 and long period-associated Per2 cooperated to rigidly confine the circadian period to “circa” 24-h. These results suggest that the rigid circadian rhythm maintained through the cooperation of Per1-Per2 could negatively impact modern society, in which the use of artificial lighting is ubiquitous, and result in circadian disorders, including delirium. PMID:27609640

  12. Rigid Cooperation of Per1 and Per2 proteins.

    PubMed

    Tamiya, Hiroyuki; Ogawa, Sumito; Ouchi, Yasuyoshi; Akishita, Masahiro

    2016-01-01

    Period circadian clock (Per) genes Per1 and Per2 have essential roles in circadian oscillation. In this study, we identified a new role of Per1-Per2 cooperation, and its mechanism, using our new experimental methods. Under constant light conditions, the period length of Per1 and Per2 knockout mice depended on the copy number ratio of Per1:Per2. We then established a light-emitting diode-based lighting system that can generate any pattern of light intensity. Under gradually changing light in the absence of phase shift with different periods, both Per1((-/-)) and Per2((-/-)) mice were entrained to a broader range of period length than wild-type mice. To analyse Per1-Per2 cooperative roles at the cell culture level, we established a Per2 knockout-rescue system, which can detect period shortening in a familial advanced sleep phase syndrome (FASPS) mutant. Upon introduction of the Per1 coding region in this system, we saw period shortening. In conclusion, short period-associated protein Per1 and long period-associated Per2 cooperated to rigidly confine the circadian period to "circa" 24-h. These results suggest that the rigid circadian rhythm maintained through the cooperation of Per1-Per2 could negatively impact modern society, in which the use of artificial lighting is ubiquitous, and result in circadian disorders, including delirium. PMID:27609640

  13. A Statistical Mechanics Approach for a Rigidity Problem

    NASA Astrophysics Data System (ADS)

    Mesón, Alejandro; Vericat, Fernando

    2007-01-01

    We focus the problem of establishing when a statistical mechanics system is determined by its free energy. A lattice system, modelled by a directed and weighted graph G (whose vertices are the spins and its adjacency matrix M will be given by the system transition rules), is considered. For a matrix A( q), depending on the system interactions, with entries which are in the ring Z[ a q : a∈ R +] and such that A(0) equals the integral matrix M, the system free energy β A ( q) will be defined as the spectral radius of A( q). This kind of free energy will be related with that normally introduced in Statistical Mechanics as proportional to the logarithm of the partition function. Then we analyze under what conditions the following statement could be valid: if two systems have respectively matrices A, B and β A = β B then the matrices are equivalent in some sense. Issues of this nature receive the name of rigidity problems. Our scheme, for finite interactions, closely follows that developed, within a dynamical context, by Pollicott and Weiss but now emphasizing their statistical mechanics aspects and including a classification for Gibbs states associated to matrices A( q). Since this procedure is not applicable for infinite range interactions, we discuss a way to obtain also some rigidity results for long range potentials.

  14. Computational Fluid Dynamics Demonstration of Rigid Bodies in Motion

    NASA Technical Reports Server (NTRS)

    Camarena, Ernesto; Vu, Bruce T.

    2011-01-01

    The Design Analysis Branch (NE-Ml) at the Kennedy Space Center has not had the ability to accurately couple Rigid Body Dynamics (RBD) and Computational Fluid Dynamics (CFD). OVERFLOW-D is a flow solver that has been developed by NASA to have the capability to analyze and simulate dynamic motions with up to six Degrees of Freedom (6-DOF). Two simulations were prepared over the course of the internship to demonstrate 6DOF motion of rigid bodies under aerodynamic loading. The geometries in the simulations were based on a conceptual Space Launch System (SLS). The first simulation that was prepared and computed was the motion of a Solid Rocket Booster (SRB) as it separates from its core stage. To reduce computational time during the development of the simulation, only half of the physical domain with respect to the symmetry plane was simulated. Then a full solution was prepared and computed. The second simulation was a model of the SLS as it departs from a launch pad under a 20 knot crosswind. This simulation was reduced to Two Dimensions (2D) to reduce both preparation and computation time. By allowing 2-DOF for translations and 1-DOF for rotation, the simulation predicted unrealistic rotation. The simulation was then constrained to only allow translations.

  15. Extracellular rigidity sensing by talin isoform–specific mechanical linkages

    PubMed Central

    Austen, Katharina; Ringer, Pia; Mehlich, Alexander; Chrostek-Grashoff, Anna; Kluger, Carleen; Klingner, Christoph; Sabass, Benedikt; Zent, Roy; Rief, Matthias; Grashoff, Carsten

    2015-01-01

    The ability of cells to adhere and sense differences in tissue stiffness is crucial for organ development and function. The central mechanisms by which adherent cells detect extracellular matrix compliance, however, are still unknown. Using two single-molecule–calibrated biosensors that allow the analysis of a previously inaccessible but physiologically highly relevant force regime in cells, we demonstrate that the integrin activator talin establishes mechanical linkages upon cell adhesion, which are indispensable for cells to probe tissue stiffness. Talin linkages are exposed to a range of piconewton (pN) forces and bear, on average, 7–10 pN during cell adhesion depending on their association with f-actin and vinculin. Disruption of talin’s mechanical engagement does not impair integrin activation and initial cell adhesion but prevents focal adhesion reinforcement and thus extracellular rigidity sensing. Intriguingly, talin mechanics are isoform-specific so that expression of either talin-1 or talin-2 modulates extracellular rigidity sensing. PMID:26523364

  16. Symmetric mode resonance of bubbles attached to a rigid boundary

    NASA Astrophysics Data System (ADS)

    Payne, Edward M. B.; Illesinghe, Suhith J.; Ooi, Andrew; Manasseh, Richard

    2005-11-01

    Experimental results are compared with a theoretical analysis concerning wall effects on the symmetric mode resonance frequency of millimeter-sized air bubbles in water. An analytical model based on a linear coupled-oscillator approximation is used to describe the oscillations of the bubbles, while the method of images is used to model the effect of the wall. Three situations are considered: a single bubble, a group of two bubbles, and a group of three bubbles. The results show that bubbles attached to a rigid boundary have lower resonance frequencies compared to when they are in an infinite uniform liquid domain (referred to as free space). Both the experimental data and theoretical analysis show that the symmetric mode resonance frequency decreases with the number of bubbles but increases as the bubbles are moved apart. Discrepancies between theory and experiment can be explained by the fact that distortion effects due to buoyancy forces and surface tension were ignored. The data presented here are intended to guide future investigations into the resonances of larger arrays of bubbles on rigid surfaces, which may assist in surface sonochemistry, sonic cleaning, and micro-mixing applications.

  17. Stability of Rigidly Rotating Supermassive Stars against Gravitational Collapse

    NASA Astrophysics Data System (ADS)

    Shibata, Masaru; Uchida, Haruki; Sekiguchi, Yu-ichiro

    2016-02-01

    We revisit secular stability against quasi-radial collapse for rigidly rotating supermassive stars (SMSs) in general relativity. We suppose that the SMSs are in a nuclear-burning phase and can be modeled by polytropic equations of state with the polytropic index np slightly smaller than 3. The stability is determined in terms of the turning point method. We find a fitting formula of the stability condition for the plausible range of np (2.95≲ {n}{{p}}≲ 3) for SMSs. This condition reconfirms that while non-rotating SMSs with a mass of ˜ {10}5{M}⊙ -{10}6{M}⊙ may undergo a general relativistically induced quasi-radial collapse, rigidly rotating SMSs with a ratio of rotational to gravitational potential energy (β) of ˜ {10}-2 are likely to be stable against collapse unless they are able to accrete ˜5 times more mass during the (relatively brief) hydrogen-burning phase of their evolution. We discuss the implications of our results.

  18. A method for measuring the inertia properties of rigid bodies

    NASA Astrophysics Data System (ADS)

    Gobbi, M.; Mastinu, G.; Previati, G.

    2011-01-01

    A method for the measurement of the inertia properties of rigid bodies is presented. Given a rigid body and its mass, the method allows to measure (identify) the centre of gravity location and the inertia tensor during a single test. The proposed technique is based on the analysis of the free motion of a multi-cable pendulum to which the body under consideration is connected. The motion of the pendulum and the forces acting on the system are recorded and the inertia properties are identified by means of a proper mathematical procedure based on a least square estimation. After the body is positioned on the test rig, the full identification procedure takes less than 10 min. The natural frequencies of the pendulum and the accelerations involved are quite low, making this method suitable for many practical applications. In this paper, the proposed method is described and two test rigs are presented: the first is developed for bodies up to 3500 kg and the second for bodies up to 400 kg. A validation of the measurement method is performed with satisfactory results. The test rig holds a third part quality certificate according to an ISO 9001 standard and could be scaled up to measure the inertia properties of huge bodies, such as trucks, airplanes or even ships.

  19. Propulsion of flexible helical flagella near a rigid boundary

    NASA Astrophysics Data System (ADS)

    Jawed, Mohammad; Reis, Pedro

    2015-11-01

    We study the locomotion of uni-flagellar bacteria in a viscous fluid at low Reynolds number near a rigid boundary, through a combination of computer simulations and experiments. In our analogue model experiments, we exploit the prominence of geometry of this class of problems to rescale the original micron-scale system onto the desktop-scale. We manufacture elastomeric filaments with fully customizable geometric and material properties, and rotate them in a glycerin bath at a finite distance away from a rigid boundary. The experimental results are compared against numerical simulations that employ the Discrete Elastic Rods method in conjunction with Lighthill Slender Body Theory. The non-slip boundary condition on the wall is implemented by the method of images. We first show that the filament buckles above a critical rotation frequency due to fluid loading, and then quantify the dependence of this critical threshold on the distance from the boundary, both experimentally and numerically. Excellent agreement is found between the two, with no fitting parameters. We then make use of our numerics to systematically investigate the change in the generated propulsion due to presence of a nearby boundary. We find that the propulsion depends strongly on the location of the boundary.

  20. Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    Combined radiation and conduction heat transfer through a high-temperature, high-porosity, rigid multiple-fiber fibrous insulation was modeled using a thermal model previously used to model heat transfer in flexible single-fiber fibrous insulation. The rigid insulation studied was alumina enhanced thermal barrier (AETB) at densities between 130 and 260 kilograms per cubic meter. The model consists of using the diffusion approximation for radiation heat transfer, a semi-empirical solid conduction model, and a standard gas conduction model. The relevant parameters needed for the heat transfer model were estimated from steady-state thermal measurements in nitrogen gas at various temperatures and environmental pressures. The heat transfer modeling methodology was evaluated by comparison with standard thermal conductivity measurements, and steady-state thermal measurements in helium and carbon dioxide gases. The heat transfer model is applicable over the temperature range of 300 to 1360 K, pressure range of 0.133 to 101.3 x 10(exp 3) Pa, and over the insulation density range of 130 to 260 kilograms per cubic meter in various gaseous environments.

  1. Machanistic basis of rigidity sensing at biological interfaces

    NASA Astrophysics Data System (ADS)

    Sarvestani, Alireza

    2011-03-01

    We have outlined a framework to investigate the thermodynamic equilibrium adhesion of a bio-membrane to a compliant substrate functionalized with immobilized bio-adhesive ligands. The membrane is modeled as a soft elastic shell, subjected to surface tension and reconstituted with mobile receptors and a repelling layer on the ventral side. The free energy function of the system is assumed to be comprised from the following contributions: the membrane--substrate non-specific interactions, stored elastic energy (in deformed membrane and substrate), binding enthalpy, and mixing entropy of mobile receptors. Assuming a van der Waals form for the interfacial non-specific potential, the equilibrium configuration of the system is studied in detail. We have shown that the equilibrium spread area of the adherent membrane is very sensitive to the rigidity of the underlying substrate and decreases as the surface compliance increases. This prediction is reminiscent of the experimental observations of spread area of cells attached to soft substrates. This is an interesting result considering the lack of contribution of intracellular signaling or actively regulated cytoskeleton in the proposed physical model for the adhesion. This suggests that the mechanistic pathways inherent to membrane--substrate thermodynamic interactions can be equally important as intracellular signaling pathways to mediate the process of rigidity sensing by cells.

  2. Awake craniotomy using electromagnetic navigation technology without rigid pin fixation.

    PubMed

    Morsy, Ahmed A; Ng, Wai Hoe

    2015-11-01

    We report our institutional experience using an electromagnetic navigation system, without rigid head fixation, for awake craniotomy patients. The StealthStation® S7 AxiEM™ navigation system (Medtronic, Inc.) was used for this technique. Detailed preoperative clinical and neuropsychological evaluations, patient education and contrast-enhanced MRI (thickness 1.5mm) were performed for each patient. The AxiEM Mobile Emitter was typically placed in a holder, which was mounted to the operating room table, and a non-invasive patient tracker was used as the patient reference device. A monitored conscious sedation technique was used in all awake craniotomy patients, and the AxiEM Navigation Pointer was used for navigation during the procedure. This offers the same accuracy as optical navigation, but without head pin fixation or interference with intraoperative neurophysiological techniques and surgical instruments. The application of the electromagnetic neuronavigation technology without rigid head fixation during an awake craniotomy is accurate, and offers superior patient comfort. It is recommended as an effective adjunctive technique for the conduct of awake surgery. PMID:26249245

  3. Supramolecular barrels from amphiphilic rigid-flexible macrocycles

    NASA Astrophysics Data System (ADS)

    Yang, Won-Young; Ahn, Jong-Hyun; Yoo, Yong-Sik; Oh, Nam-Keun; Lee, Myongsoo

    2005-05-01

    Precise control of supramolecular objects requires the rational design of molecular components, because the information determining their specific assembly should be encoded in their molecular architecture. In this context, diverse self-assembling molecules including liquid crystals, dendrimers, block copolymers, hydrogen-bonded complexes and rigid macrocycles are being created as a means of manipulating supramolecular structure. Incorporation of a stiff rod-like building block into an amphiphilic molecular architecture leads to another class of self-assembling molecules. Aggregation of rod building blocks can generate various nanoscale objects including bundles, ribbons, tubules and vesicles, depending on the molecular structure and/or the presence of a selective solvent. We present here an unusual example of supramolecular barrels in the solid and in aqueous solution, based on the self-assembly of amphiphilic rigid-flexible macrocycles driven by non-covalent interactions. Preliminary experiments show that these amphiphilic macrocycles are membrane-active. The amphiphilic macrocycles might thus lead to an excellent model system for exploring biological processes in supramolecular materials.

  4. Sufficiency of Longitudinal Moment of Inertia for Haptic Cylinder Length Judgments

    ERIC Educational Resources Information Center

    Cabe, Patrick A.

    2010-01-01

    Many studies invoke moment of inertia (I[subscript ii]) as necessary and sufficient information to perceive cylinder length via wielding, yet some assert that I[subscript ii] is neither necessary (weight, "m", or static moment, M, are sufficient) nor sufficient for length judgments ("m" or M is necessary). Mathematical expressions for I[subscript…

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

    PubMed Central

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

    2014-01-01

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

  6. Effects of STN DBS on Rigidity in Parkinson’s Disease

    PubMed Central

    Shapiro, Mark B.; Vaillancourt, David E.; Sturman, Molly M.; Metman, Leo Verhagen; Bakay, Roy A. E.; Corcos, Daniel M.

    2008-01-01

    We quantified the effects of deep brain stimulation (DBS) of the subthalamic nucleus (STN) and medication on Parkinsonian rigidity using an objective measure of work about the elbow joint during a complete cycle of imposed 1-Hz sinusoidal oscillations. Resting and activated rigidity were analyzed in four experimental conditions: 1) off treatment; 2) on DBS; 3) on medication; and 4) on DBS plus medication. Rigidity at the elbow joint was also assessed using the Unified Parkinson’s Disease Rating Scale (UPDRS). We tested ten patients who received STN DBS and ten age-matched neurologically healthy control subjects. The activated rigidity condition increased work in both Parkinson’s disease (PD) patients and control subjects. In PD patients, STN DBS reduced both resting and activated rigidity as indicated by work and the UPDRS rigidity score. This is the first demonstration that STN stimulation reduces rigidity using an objective measure such as work. In contrast, the presurgery dose of antiparkinsonian medication did not significantly improve the UPDRS rigidity score and reduced work only in the activated rigidity condition. Our results suggest that STN DBS may be more effective in alleviating rigidity in the upper limb of PD patients than medications administered at presurgery dosage level. PMID:17601186

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

    PubMed Central

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

    2016-01-01

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

  8. Minimal sufficient positive-operator valued measure on a separable Hilbert space

    SciTech Connect

    Kuramochi, Yui

    2015-10-15

    We introduce a concept of a minimal sufficient positive-operator valued measure (POVM), which is the least redundant POVM among the POVMs that have the equivalent information about the measured quantum system. Assuming the system Hilbert space to be separable, we show that for a given POVM, a sufficient statistic called a Lehmann-Scheffé-Bahadur statistic induces a minimal sufficient POVM. We also show that every POVM has an equivalent minimal sufficient POVM and that such a minimal sufficient POVM is unique up to relabeling neglecting null sets. We apply these results to discrete POVMs and information conservation conditions proposed by the author.

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

    SciTech Connect

    Maeda, Takenori

    1995-11-01

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

  10. The space-developed dynamic vertical cutoff rigidity model and its applicability to aircraft radiation dose.

    PubMed

    Smart, D F; Shea, M A

    2003-01-01

    We have developed a dynamic geomagnetic vertical cutoff rigidity model that predicts the energetic charged particle transmission through the magnetosphere. Initially developed for space applications, we demonstrate the applicability of this library of cutoff rigidity models for computing aircraft radiation dose. The world grids of vertical cutoff rigidities were obtained by particle trajectory tracing in a magnetospheric model. This reference set of world grids of vertical cutoff rigidities calculated for satellite altitudes covers all magnetic activity levels from super quiet to extremely disturbed (i.e., Kp indices ranging from 0 to 9+) for every three hours in universal time. We utilize the McIlwain "L" parameter as the basis of the interpolation technique to reduce these initial satellite altitude vertical cutoff rigidities to cutoff rigidity values at aircraft altitudes.

  11. Recommendations to resolve inconsistent guidelines for the reprocessing of sheathed and unsheathed rigid laryngoscopes.

    PubMed

    Muscarella, Lawrence F

    2007-04-01

    Neither a consensus statement nor a formal set of step-by-step guidelines for reprocessing rigid laryngoscopes have been published or endorsed by professional organizations. Several published guidelines, standards, and clinical reports were reviewed to evaluate the risk of nosocomial infection associated with the use of rigid laryngoscopes, to determine their minimum reprocessing requirements. This review found that the recommendations of some guidelines and standards for reprocessing rigid laryngoscopes are incomplete, inadequate, and inconsistent with one another, and that current practices for reprocessing rigid laryngoscopes are reported to be inadequate and lack standardization. It is recommended that a consensus statement be developed that standardizes the reprocessing of rigid laryngoscopes and requires cleaning followed by high-level disinfection (or sterilization) and drying of the rigid laryngoscope's blade and handle to prevent nosocomial infection, regardless of whether a protective barrier or sheath is used during the procedure.

  12. Inertial and viscoelastic forces on rigid colloids in microfluidic channels.

    PubMed

    Howard, Michael P; Panagiotopoulos, Athanassios Z; Nikoubashman, Arash

    2015-06-14

    We perform hybrid molecular dynamics simulations to study the flow behavior of rigid colloids dispersed in a dilute polymer solution. The underlying Newtonian solvent and the ensuing hydrodynamic interactions are incorporated through multiparticle collision dynamics, while the constituent polymers are modeled as bead-spring chains, maintaining a description consistent with the colloidal nature of our system. We study the cross-stream migration of the solute particles in slit-like channels for various polymer lengths and colloid sizes and find a distinct focusing onto the channel center under specific solvent and flow conditions. To better understand this phenomenon, we systematically measure the effective forces exerted on the colloids. We find that the migration originates from a competition between viscoelastic forces from the polymer solution and hydrodynamically induced inertial forces. Our simulations reveal a significantly stronger fluctuation of the lateral colloid position than expected from thermal motion alone, which originates from the complex interplay between the colloid and polymer chains.

  13. Debris flow impact estimation on a rigid barrier

    NASA Astrophysics Data System (ADS)

    Vagnon, Federico; Segalini, Andrea

    2016-07-01

    The aim of this paper is to analyse debris flow impact against rigid and undrained barrier in order to propose a new formulation for the estimation of acting force after the flow impact to safe design protection structures. For this reason, this work concentrates on the flow impact, by performing a series of small scale tests in a specifically created flume. Flow characteristics (flow height and velocity) and applied loads (dynamic and static) on barrier were measured using four ultrasonic devices, four load cells and a contact surface pressure gauge. The results obtained were compared with main existing models and a new equation is proposed. Furthermore, a brief review of the small scale theory was provided to analyse the scale effects that can affect the results.

  14. Rigid Calabi-Yau threefolds, Picard Eisenstein series and instantons

    NASA Astrophysics Data System (ADS)

    Bao, L.; Kleinschmidt, A.; Nilsson, B. E. W.; Persson, D.; Pioline, B.

    2013-12-01

    Type IIA string theory compactified on a rigid Calabi-Yau threefold gives rise to a classical moduli space that carries an isometric action of U(2, 1). Various quantum corrections break this continuous isometry to a discrete subgroup. Focussing on the case where the intermediate Jacobian of the Calabi-Yau admits complex multiplication by the ring of quadratic imaginary integers d, we argue that the remaining quantum duality group is an arithmetic Picard modular group PU(2, 1; d). Based on this proposal we construct an Eisenstein series invariant under this duality group and study its non-Abelian Fourier expansion. This allows the prediction of non-perturbative effects, notably the contribution of D2- and NS5-brane instantons. The present work extends our previous analysis in 0909.4299 which was restricted to the special case of the Gaussian integers 1 = Bbb Z[i].

  15. Cenozoic Eurasia is not a single rigid plate: Paleomagnetic evidence

    NASA Astrophysics Data System (ADS)

    Cogné, Jean-Pascal

    2013-11-01

    The widely distributed Cenozoic paleomagnetic inclination anomaly in Asia is usually attributed to either a widespread error of magnetic field recording due to an inclination flattening mechanism in sediments, or to the persistence of an anomalous non-dipolar component of the geomagnetic field throughout the Tertiary. Based on an analysis of the Asian paleomagnetic database for Meso-Cenozoic times, we suggest that instead this puzzling anomaly results from an overlooked global plate tectonics cause where the wide so-called Eurasian plate would have suffered from previously undetected transpressive north-south relative movements between its western and eastern ends since the Cretaceous. These relative movements are most probably accommodated by a component of right-lateral shear movement distributed in the Tornquist-Tesseyre zone, and a localized left-lateral shear movement in the Ural Mountain chain during the Tertiary. Therefore, Eurasia was not the single rigid plate that Cenozoic plate reconstructions have accepted.

  16. Comparing turbulence models for flow through a rigid glottal model.

    PubMed

    Suh, Jungsoo; Frankel, Steven H

    2008-03-01

    Flow through a rigid model of the human vocal tract featuring a divergent glottis was numerically modeled using the Reynolds-averaged Navier-Stokes approach. A number of different turbulence models, available in a widely used commercial computational fluid dynamics code, were tested to determine their ability to capture various flow features recently observed in laboratory experiments and large eddy simulation studies. The study reveals that results from unsteady simulations employing the k-omega shear stress transport model were in much better agreement with previous measurements and predictions with regard to the ability to predict glottal jet skewing due to the Coanda effect and the intraglottal pressure distribution or related skin friction coefficient, than either steady or unsteady simulations using the Spalart-Allmaras model or any other two-equation turbulence model investigated in this study. PMID:18345812

  17. Smooth Rotation Enhanced As-Rigid-As-Possible Mesh Animation.

    PubMed

    Levi, Zohar; Gotsman, Craig

    2015-02-01

    In recent years, the As-Rigid-As-Possible (ARAP) shape deformation and shape interpolation techniques gained popularity, and the ARAP energy was successfully used in other applications as well. We improve the ARAP animation technique in two aspects. First, we introduce a new ARAP-type energy, named SR-ARAP, which has a consistent discretization for surfaces (triangle meshes). The quality of our new surface deformation scheme competes with the quality of the volumetric ARAP deformation (for tetrahedral meshes). Second, we propose a new ARAP shape interpolation method that is superior to prior art also based on the ARAP energy. This method is compatible with our new SR-ARAP energy, as well as with the ARAP volume energy.

  18. Underwater sound of rigid-hulled inflatable boats.

    PubMed

    Erbe, Christine; Liong, Syafrin; Koessler, Matthew Walter; Duncan, Alec J; Gourlay, Tim

    2016-06-01

    Underwater sound of rigid-hulled inflatable boats was recorded 142 times in total, over 3 sites: 2 in southern British Columbia, Canada, and 1 off Western Australia. Underwater sound peaked between 70 and 400 Hz, exhibiting strong tones in this frequency range related to engine and propeller rotation. Sound propagation models were applied to compute monopole source levels, with the source assumed 1 m below the sea surface. Broadband source levels (10-48 000 Hz) increased from 134 to 171 dB re 1 μPa @ 1 m with speed from 3 to 16 m/s (10-56 km/h). Source power spectral density percentile levels and 1/3 octave band levels are given for use in predictive modeling of underwater sound of these boats as part of environmental impact assessments. PMID:27369176

  19. Emergent Behavior in the Macro World: Rigidity of Granular Solids

    NASA Astrophysics Data System (ADS)

    Chakraborty, Bulbul

    2015-03-01

    Diversity in the natural world emerges from the collective behavior of large numbers of interacting objects. The origin of collectively organized structures over the vast range of length scales from the subatomic to colloidal is the competition between energy and entropy. Thermal motion provides the mechanism for organization by allowing particles to explore the space of configurations. This well-established paradigm of emergent behavior breaks down for collections of macroscopic objects ranging from grains of sand to asteroids. In this macro-world of particulate systems, thermal motion is absent, and mechanical forces are all important. We lack understanding of the basic, unifying principles that underlie the emergence of order in this world. In this talk, I will explore the origin of rigidity of granular solids, and present a new paradigm for emergence of order in these athermal systems. This work has been supported by NSF-DMR 1409093 and by the W. M. Keck foundation

  20. Shear-Induced Chiral Migration of Particles with Anisotropic Rigidity

    NASA Astrophysics Data System (ADS)

    Watari, Nobuhiko; Larson, Ronald G.

    2009-06-01

    We report that an achiral particle with anisotropic rigidity can migrate in the vorticity direction in shear flow. A minimal “tetrumbbell” model of such a particle is constructed from four beads and six springs to make a tetrahedral structure. A combination of two different spring constants corresponding to “hard” and “soft” springs yields ten distinguishable tetrumbbells, which when simulated in shear flow with hydrodynamic interactions between beads but no Brownian motion at zero Reynolds number, produces five different types of behavior in which seven out of ten tetrumbbell structures migrate in the vorticity direction due to shear-induced chirality. Some of the structures migrate in the same direction along the vorticity direction even when the shear flow is reversed, which is impossible for permanently chiral objects.

  1. Fibrillar Organic Phases And Their Roles In Rigid Biological Composites

    SciTech Connect

    Arey, Bruce W.; Park, John J.; Mayer, George

    2015-06-01

    This study focused on determining the presence of organic phases in the siliceous components of rigid marine composites ("glass" sponge spicules), and thereby to clarify how those composites dissipate significant mechanical energy. Through the use of imaging by helium ion microscopy in the examination of the spicules, the organic phase that is present between the layers of hydrated silica was also detected within the silica cylinders of the composite, indicating the existence therein of a network, scaffolding, or other pattern that has not yet been determined. It was concluded that the presence of an interpenetrating network of some kind, and tenacious fibrillar interfaces are responsible for the large energy dissipation in these siliceous composites by viscoelastic processes. This discovery means that future mechanics analyses of such composites, extending to large deformations must consider such interpenetrating phases.

  2. Complexity management theory: motivation for ideological rigidity and social conflict.

    PubMed

    Peterson, Jordan B; Flanders, Joseph L

    2002-06-01

    We are doomed to formulate conceptual structures that are much simpler than the complex phenomena they are attempting to account for. These simple conceptual structures shield us, pragmatically, from real-world complexity, but also fail, frequently, as some aspect of what we did not take into consideration makes itself manifest. The failure of our concepts dysregulates our emotions and generates anxiety, necessarily, as the unconstrained world is challenging and dangerous. Such dysregulation can turn us into rigid, totalitarian dogmatists, as we strive to maintain the structure of our no longer valid beliefs. Alternatively, we can face the underlying complexity of experience, voluntarily, gather new information, and recast and reconfigure the structures that underly our habitable worlds.

  3. Large scale rigidity-based flexibility analysis of biomolecules

    PubMed Central

    Streinu, Ileana

    2016-01-01

    KINematics And RIgidity (KINARI) is an on-going project for in silico flexibility analysis of proteins. The new version of the software, Kinari-2, extends the functionality of our free web server KinariWeb, incorporates advanced web technologies, emphasizes the reproducibility of its experiments, and makes substantially improved tools available to the user. It is designed specifically for large scale experiments, in particular, for (a) very large molecules, including bioassemblies with high degree of symmetry such as viruses and crystals, (b) large collections of related biomolecules, such as those obtained through simulated dilutions, mutations, or conformational changes from various types of dynamics simulations, and (c) is intended to work as seemlessly as possible on the large, idiosyncratic, publicly available repository of biomolecules, the Protein Data Bank. We describe the system design, along with the main data processing, computational, mathematical, and validation challenges underlying this phase of the KINARI project. PMID:26958583

  4. Local rigidity and physical trends in embedded Si nanocrystals

    NASA Astrophysics Data System (ADS)

    Kleovoulou, K.; Kelires, P. C.

    2013-12-01

    We investigate the problem of local rigidity of Si nanocrystals embedded in amorphous silica. By analyzing the elastic (bulk) modulus field into atomic contributions, we show that it is highly inhomogeneous. It consists of a hard region in the interior of the nanocrystals, with moduli ˜105 GPa, compared to 98 GPa for bulk Si, and of "superhard" (˜120 GPa) and "supersoft" (˜80 GPa) regions in the outer parts. Overall, the nanocrystal bulk modulus is significantly enhanced compared to the bulk, and its variation with size accurately follows a power-law dependence on the average bond length. The bulk modulus of the oxide matrix and of the interface region is nearly constant with size, with values 60 and 70 GPa, respectively. The average optical (homopolar) gap is directly linked to the elastic and bond-length variations.

  5. Testing the disturbed zone around a rigid inclusion in salt

    SciTech Connect

    Knowles, M.K.; Borns, D.; Fredrich, J.; Holcomb, D.; Price, R.; Zeuch, D.; Dale, T.; Van Pelt, R.S.

    1996-12-01

    Deformational processes within a zone of rock surrounding excavations in salt result in alteration of the geophysical and hydrologic properties as compared to the undisturbed condition. The disturbed rock zone offers little resistance to fluid flow. It is hypothesized that rigid inclusions such as concrete seals will arrest and subsequently reverse the disturbance process and induce healing in the disturbed This experiment gathered in situ data that substantiates this hypothesis. A series of tests was conducted in a volume of rock surrounding concrete seals that were placed in a 1-m borehole approximately eight years ago. Fluid flow measurements, measurements of geophysical parameters of the surrounding rock and petrographic analyses on core samples were performed to characterize the rock. This paper presents the testing methodology and summarizes the data gathered from the field test program.

  6. Origin of the Low Rigidity of the Earth's Inner Core

    NASA Astrophysics Data System (ADS)

    Belonoshko, A. B.; Skorodumova, N. V.; Davis, S.; Osiptsov, A. N.; Rosengren, A.; Johansson, B.

    2007-12-01

    The solid iron Earth's inner core has a low rigidity which manifests itself in the anomalously low velocities of shear waves as compared to those in iron alloys. Normally, when estimating elastic properties of a polycrystal one calculates an average over different orientations of a single crystal. This approach does not take into account the grain boundaries and defects likely to be abundant at high temperatures relevant for the inner core conditions. We show, by molecular dynamics simulations that if defects are considered, the calculated shear modulus and shear wave velocity decrease dramatically compared to the averaged single crystal values. Thus, the low shear wave velocity in the inner core receives its explanation (Science 316, 1603 (2007)).

  7. Photoinduced anisotropy in rigid dye solutions for transient polarization holography

    NASA Astrophysics Data System (ADS)

    Todorov, T.; Nikolova, L.; Tomova, N.; Dragostinova, V.

    1986-08-01

    The photochromic properties of three rigid dyes solutions were assessed experimentally. The dyes, susceptible to induced photooptical anisotropy, are candidates as recording media for transient polarization holography. Attention is focused on the transitions from singlet to triplet states in fluorescein/orthoboric acid (FOA), isomeric transformations in methyl red/polymer matrices, and molecular reorientations in methyl orange/polyvinylalchol (MOP) in response to degenerate four-wave mixing laser hologroaphy. Various combinations of linear, orthogonal and circular polarizations were tested. All three dye/matrix systems resisted fatigue past 10,000 erasure cycles, with the FOA system exhibiting the shortest response time, 0.1 sec. The MOP mixture displayed a diffraction efficiency of nearly 35 percent. Techniques for accelerating the recording processes for using the dyes in holography to study phenomena such as energy transfer and wavefront reversal are discussed.

  8. Osseous adaptation to continuous loading of rigid endosseous implants

    NASA Technical Reports Server (NTRS)

    Roberts, W. E.; Smith, R. K.; Mozsary, P. G.; Zilberman, Y.; Smith, R. S.

    1984-01-01

    The effect of loading on etched Ti implants in the femurs of young (3 mo) and adult (6 mo) rabbits is investigated experimentally. The results are presented in photographs, fluorescence and polarization micrographs, radiographs, and drawings and discussed. Implantation is followed by formation of coarse woven bone within 3 d and mature lamellar bone by 6 wks, with nonspecific subperiosteal bony hypertrophy in the young rabbits only. Spring loading at 100 g produces spontaneous spiral-type fractures when applied immediately, but the implants remain rigid when loads are applied after 6-12 wks of healing. The mechanisms of bone formation involved are examined, and the potential of endosseous implants as anchors in orthodontics or dentofacial-orthopedics is confirmed.

  9. Glycolysis recycling of rigid waste polyurethane foam from refrigerators.

    PubMed

    Zhu, P; Cao, Z B; Chen, Y; Zhang, X J; Qian, G R; Chu, Y L; Zhou, M

    2014-01-01

    Rapid growth of rigid waste polyurethane (WPUR) foam from refrigerators attracts the attention all over the world. In this study, glycolysis was chosen to treat WPUR from scrapped refrigerators collected in Shanghai, China. Glycolysis reagents and catalysts were selected. The results indicated that the glycolysis efficiency of ethylene glycol (EG) was higher than that of diethylene glycol, and the catalytic efficiency of alkali metal salts (NaOH) was more excellent than that of triethanolamine and organic salts of alkali metal (NaAc). When EG was 100%WPUR as a glycolysis reagent and NaOH was 1%WPUR as a catalyst at a constant temperature of 197.85°C for 2 h, the glycolysis product had the highest glycolysis conversion rate. In order to maximize the recycling of WPUR, regenerative Polyurethane was performed by adding 10% distilled mixed polyol, which conformed to the QB/T 26689-2011 requirements. PMID:25176301

  10. Computer program for determining mass properties of a rigid structure

    NASA Technical Reports Server (NTRS)

    Hull, R. A.; Gilbert, J. L.; Klich, P. J.

    1978-01-01

    A computer program was developed for the rapid computation of the mass properties of complex structural systems. The program uses rigid body analyses and permits differences in structural material throughout the total system. It is based on the premise that complex systems can be adequately described by a combination of basic elemental shapes. Simple geometric data describing size and location of each element and the respective material density or weight of each element were the only required input data. From this minimum input, the program yields system weight, center of gravity, moments of inertia and products of inertia with respect to mutually perpendicular axes through the system center of gravity. The program also yields mass properties of the individual shapes relative to component axes.

  11. Rigid band analysis of heavily doped semiconductor devices

    NASA Astrophysics Data System (ADS)

    Marshak, A. H.; Shibib, M. A.; Fossum, J. G.; Lindholm, F. A.

    1981-03-01

    The conventional carrier transport equations used in device analysis must be modified for heavily doped semiconductor regions. The modifications to Shockley's auxiliary equations relating the carrier densities to their corresponding quasi-Fermi levels are derived for the rigid band model. The effects of asymmetric bandgap narrowing and of carrier degeneracy (Fermi-Dirac statistics) are induced. Emphasis is placed on writing the equations in a simple form that indicates the effect of changes in the band structure due to heavy doping. In this form they can serve as a basis for computer-aided analysis and design. It is shown that, in general, the effective intrinsic carrier density as well as the electron and hole current densities depend on the asymmetry in bandgap narrowing.

  12. Geometry-induced rigidity in nonspherical pressurized elastic shells.

    PubMed

    Lazarus, A; Florijn, H C B; Reis, P M

    2012-10-01

    We present results from an experimental investigation of the indentation of nonspherical pressurized elastic shells with a positive Gauss curvature. A predictive framework is proposed that rationalizes the dependence of the local rigidity of an indented shell on the curvature in the neighborhood of the locus of indentation, the in-out pressure differential, and the material properties. In our approach, we combine classic theory for spherical shells with recent analytical developments for the pressurized case, and proceed, for the most part, by analogy, guided by our own experiments. By way of example, our results elucidate why an eggshell is significantly stiffer when compressed along its major axis, as compared to doing so along its minor axis. The prominence of geometry in this class of problems points to the relevance and applicability of our findings over a wide range of length scales. PMID:23083245

  13. Geometry-induced rigidity in nonspherical pressurized elastic shells.

    PubMed

    Lazarus, A; Florijn, H C B; Reis, P M

    2012-10-01

    We present results from an experimental investigation of the indentation of nonspherical pressurized elastic shells with a positive Gauss curvature. A predictive framework is proposed that rationalizes the dependence of the local rigidity of an indented shell on the curvature in the neighborhood of the locus of indentation, the in-out pressure differential, and the material properties. In our approach, we combine classic theory for spherical shells with recent analytical developments for the pressurized case, and proceed, for the most part, by analogy, guided by our own experiments. By way of example, our results elucidate why an eggshell is significantly stiffer when compressed along its major axis, as compared to doing so along its minor axis. The prominence of geometry in this class of problems points to the relevance and applicability of our findings over a wide range of length scales.

  14. Investigation of Drag Coefficient for Rigid Ballute-like Shapes

    NASA Astrophysics Data System (ADS)

    Carnasciali, Maria-Isabel; Mastromarino, Anthony

    2014-11-01

    One common method of decelerating an object during atmospheric entry, descent, and landing is the use of parachutes. Another deceleration technology is the ballute - a combination of balloon and parachute. A CFD study was conducted using commercially available software to investigate the flow-field and the coefficient of drag for various rigid ballute-like shapes at varying Reynolds numbers. The impact of size and placement of the burble-fence as well as number, size, and shape of inlets was considered. Recent experimental measurements conducted during NASA's Low-Density Supersonic Decelerator program revealed a much higher coefficient of drag (Cd) for ballutes than previously encountered. Using atmospheric drag to slow down and land reduces the need for heavy fuel and rocket engines and thus, high values of drag are desired. Funding for this work, in part, provided by the CT Space Grant Consortium.

  15. Stability diagrams for a rigid gyrostat in a circular orbit

    NASA Astrophysics Data System (ADS)

    Hughes, P. C.; Golla, D. F.

    1984-05-01

    The dynamics of a rigid gyrostat travelling in a circular orbit are reviewed. The two torques to be balanced are the gyroscopic torque associated with the once per orbit precession of the in plane angular momentum vector, and the gravitational torque that results from the principal inertial axes not being aligned with the orbiting axes. Different methods of balancing these two torques lead to different classes of relative equilibria, viz., the cylindrical case, the conical case, the hyperbolic case, and the general case. The principal contribution is to present a large number of stability diagrams for the many different cases and subcases that arise. A large number of equilbria are, in fact, unstable. However, as shown here, they can usually be stabilized by adding a momentum wheel aligned with the pitch axis.

  16. Glycolysis recycling of rigid waste polyurethane foam from refrigerators.

    PubMed

    Zhu, P; Cao, Z B; Chen, Y; Zhang, X J; Qian, G R; Chu, Y L; Zhou, M

    2014-01-01

    Rapid growth of rigid waste polyurethane (WPUR) foam from refrigerators attracts the attention all over the world. In this study, glycolysis was chosen to treat WPUR from scrapped refrigerators collected in Shanghai, China. Glycolysis reagents and catalysts were selected. The results indicated that the glycolysis efficiency of ethylene glycol (EG) was higher than that of diethylene glycol, and the catalytic efficiency of alkali metal salts (NaOH) was more excellent than that of triethanolamine and organic salts of alkali metal (NaAc). When EG was 100%WPUR as a glycolysis reagent and NaOH was 1%WPUR as a catalyst at a constant temperature of 197.85°C for 2 h, the glycolysis product had the highest glycolysis conversion rate. In order to maximize the recycling of WPUR, regenerative Polyurethane was performed by adding 10% distilled mixed polyol, which conformed to the QB/T 26689-2011 requirements.

  17. Thermal conductivity of rigid foam insulations for aerospace vehicles

    NASA Astrophysics Data System (ADS)

    Barrios, M.; Van Sciver, S. W.

    2013-05-01

    The present work describes measurements of the effective thermal conductivity of NCFI 24-124 foam, a spray-on foam insulation used formerly on the Space Shuttle external fuel tank. A novel apparatus to measure the effective thermal conductivity of rigid foam at temperatures ranging from 20 K to 300 K was developed and used to study three samples of NCFI 24-124 foam insulation. In preparation for measurement, the foam samples were either treated with a uniquely designed moisture absorption apparatus or different residual gases to study their impact on the effective thermal conductivity of the foam. The resulting data are compared to other measurements and mathematical models reported in the literature.

  18. "False" migration of rigid fixation appliances in pediatric craniofacial surgery.

    PubMed

    Papay, F A; Hardy, S; Morales, L; Walker, M; Enlow, D

    1995-07-01

    Osseous fixation techniques have been widely used to provide rigid stabilization in the craniofacial skeleton. Reported sequelae of its usage has been limited to palpation of the screw-plate system and radiological imaging artifacts. Over the past 3 years we have identified miniplates, microplates, and wire sutures on the inner cranial table of the growing child. The observation of "false" migration of these appliances has provided the impetus to review these patients in more detail. Twenty patients underwent secondary cranial remodeling within a two-year period; 7 of these patients were seen to have "false" migration. There were no untoward sequelae in removal of these appliances, and no adverse neurological symptoms were seen.

  19. Rigid plastic balls as enrichment devices for captive chimpanzees.

    PubMed

    Bloomsmith, M A; Finlay, T W; Merhalski, J J; Maple, T L

    1990-05-01

    The use of rigid, plastic balls as enrichment devices for 16 captive chimpanzees was studied at The University of Texas M.D. Anderson Cancer Center chimpanzee colony. After the subjects were presented with balls, 10 hours of data were collected for each subject using a scan-sampling technique. The mean percentage of ball-use time for all subjects during the study was 7.1%. There was no sex difference in ball use. Age and housing effects were obtained, with younger animals and those housed in more barren environments exhibiting higher levels of ball use. It is concluded that the balls were worthwhile additions to the chimpanzee environments with use stabilizing at a mean of 2.5% of the subjects' time.

  20. JOINT RIGIDITY ASSESSMENT WITH PIEZOELECTRIC WAFERS AND ACOUSTIC WAVES

    SciTech Connect

    Montoya, Angela C.; Maji, Arup K.

    2010-02-22

    There has been an interest in the development of rapid deployment satellites. In a modular satellite design, different panels of specific functions can be pre-manufactured. The satellite can then be assembled and tested just prior to deployment. Traditional vibration testing is time-consuming and expensive. An alternative test method to evaluate the connection between two plates will be proposed. The method investigated and described employs piezoelectric wafers to induce and sense lamb waves in two aluminum plates, which were joined by steel brackets to form an 'L-Style' joint. Lamb wave behavior and piezoelectric material properties will be discussed; the experimental setup and results will be presented. A set of 4 piezoelectric ceramic wafers were used alternately as source and sensor. The energy transmitted was shown to correlate with a mechanical assessment of the joint, demonstrating that this method of testing is a feasible and reliable way to inspect the rigidity of joints.

  1. Absolute and relative choreographies in rigid body dynamics

    NASA Astrophysics Data System (ADS)

    Borisov, A. V.; Kilin, A. A.; Mamaev, I. S.

    2008-06-01

    For the classical problem of motion of a rigid body about a fixed point with zero area integral, we present a family of solutions that are periodic in the absolute space. Such solutions are known as choreographies. The family includes the well-known Delone solutions (for the Kovalevskaya case), some particular solutions for the Goryachev-Chaplygin case, and the Steklov solution. The “genealogy” of solutions of the family naturally appearing from the energy continuation and their connection with the Staude rotations are considered. It is shown that if the integral of areas is zero, the solutions are periodic with respect to a coordinate frame that rotates uniformly about the vertical (relative choreographies).

  2. Use of beam probes for rigidity calibration of the A1900 fragment separator

    NASA Astrophysics Data System (ADS)

    Ginter, T. N.; Farinon, F.; Baumann, T.; Hausmann, M.; Kwan, E.; Naviliat Cuncic, O.; Portillo, M.; Rogers, A. M.; Stetson, J.; Sumithrarachchi, C.; Villari, A. C. C.; Williams, S. J.

    2016-06-01

    Use of a beam-based approach is presented for establishing a rigidity calibration for the A1900 fragment separator located at the National Superconducting Cyclotron Laboratory. Also presented is why an alternative approach to the rigidity calibration - using detailed field maps of individual magnetic components - is not a feasible basis for deriving an accurate calibration. The level of accuracy achieved for the rigidity calibration is ±0.1%.

  3. Monte Carlo-based rigid body modelling of large protein complexes against small angle scattering data.

    PubMed

    Meesters, Christian; Pairet, Bruno; Rabenhorst, Anja; Decker, Heinz; Jaenicke, Elmar

    2010-06-01

    We present a modular, collaborative, open-source architecture for rigid body modelling based upon small angle scattering data, named sas_rigid. It is designed to provide a fast and extensible scripting interface using the easy-to-learn Python programming language. Features include rigid body modelling to result in static structures and three-dimensional probability densities using two different algorithms. PMID:20598639

  4. Non-rigid multi-modal registration on the GPU

    NASA Astrophysics Data System (ADS)

    Vetter, Christoph; Guetter, Christoph; Xu, Chenyang; Westermann, Rüdiger

    2007-03-01

    Non-rigid multi-modal registration of images/volumes is becoming increasingly necessary in many medical settings. While efficient registration algorithms have been published, the speed of the solutions is a problem in clinical applications. Harnessing the computational power of graphics processing unit (GPU) for general purpose computations has become increasingly popular in order to speed up algorithms further, but the algorithms have to be adapted to the data-parallel, streaming model of the GPU. This paper describes the implementation of a non-rigid, multi-modal registration using mutual information and the Kullback-Leibler divergence between observed and learned joint intensity distributions. The entire registration process is implemented on the GPU, including a GPU-friendly computation of two-dimensional histograms using vertex texture fetches as well as an implementation of recursive Gaussian filtering on the GPU. Since the computation is performed on the GPU, interactive visualization of the registration process can be done without bus transfer between main memory and video memory. This allows the user to observe the registration process and to evaluate the result more easily. Two hybrid approaches distributing the computation between the GPU and CPU are discussed. The first approach uses the CPU for lower resolutions and the GPU for higher resolutions, the second approach uses the GPU to compute a first approximation to the registration that is used as starting point for registration on the CPU using double-precision. The results of the CPU implementation are compared to the different approaches using the GPU regarding speed as well as image quality. The GPU performs up to 5 times faster per iteration than the CPU implementation.

  5. Inertial modes of rigidly rotating neutron stars in Cowling approximation

    SciTech Connect

    Kastaun, Wolfgang

    2008-06-15

    In this article, we investigate inertial modes of rigidly rotating neutron stars, i.e. modes for which the Coriolis force is dominant. This is done using the assumption of a fixed spacetime (Cowling approximation). We present frequencies and eigenfunctions for a sequence of stars with a polytropic equation of state, covering a broad range of rotation rates. The modes were obtained with a nonlinear general relativistic hydrodynamic evolution code. We further show that the eigenequations for the oscillation modes can be written in a particularly simple form for the case of arbitrary fast but rigid rotation. Using these equations, we investigate some general characteristics of inertial modes, which are then compared to the numerically obtained eigenfunctions. In particular, we derive a rough analytical estimate for the frequency as a function of the number of nodes of the eigenfunction, and find that a similar empirical relation matches the numerical results with unexpected accuracy. We investigate the slow rotation limit of the eigenequations, obtaining two different sets of equations describing pressure and inertial modes. For the numerical computations we only considered axisymmetric modes, while the analytic part also covers nonaxisymmetric modes. The eigenfunctions suggest that the classification of inertial modes by the quantum numbers of the leading term of a spherical harmonic decomposition is artificial in the sense that the largest term is not strongly dominant, even in the slow rotation limit. The reason for the different structure of pressure and inertial modes is that the Coriolis force remains important in the slow rotation limit only for inertial modes. Accordingly, the scalar eigenequation we obtain in that limit is spherically symmetric for pressure modes, but not for inertial modes.

  6. A rigid motion correction method for helical computed tomography (CT)

    NASA Astrophysics Data System (ADS)

    Kim, J.-H.; Nuyts, J.; Kyme, A.; Kuncic, Z.; Fulton, R.

    2015-03-01

    We propose a method to compensate for six degree-of-freedom rigid motion in helical CT of the head. The method is demonstrated in simulations and in helical scans performed on a 16-slice CT scanner. Scans of a Hoffman brain phantom were acquired while an optical motion tracking system recorded the motion of the bed and the phantom. Motion correction was performed by restoring projection consistency using data from the motion tracking system, and reconstructing with an iterative fully 3D algorithm. Motion correction accuracy was evaluated by comparing reconstructed images with a stationary reference scan. We also investigated the effects on accuracy of tracker sampling rate, measurement jitter, interpolation of tracker measurements, and the synchronization of motion data and CT projections. After optimization of these aspects, motion corrected images corresponded remarkably closely to images of the stationary phantom with correlation and similarity coefficients both above 0.9. We performed a simulation study using volunteer head motion and found similarly that our method is capable of compensating effectively for realistic human head movements. To the best of our knowledge, this is the first practical demonstration of generalized rigid motion correction in helical CT. Its clinical value, which we have yet to explore, may be significant. For example it could reduce the necessity for repeat scans and resource-intensive anesthetic and sedation procedures in patient groups prone to motion, such as young children. It is not only applicable to dedicated CT imaging, but also to hybrid PET/CT and SPECT/CT, where it could also ensure an accurate CT image for lesion localization and attenuation correction of the functional image data.

  7. Rigidity and Fluidity in Living and Nonliving Matter

    NASA Astrophysics Data System (ADS)

    Lopez, Jorge H.

    Many of the standard equilibrium statistical mechanics techniques do not readily apply to non-equilibrium phase transitions such as the fluid-to-disordered solid transition found in repulsive particulate systems. Examples of repulsive particulate systems are sand grains and colloids. The first part of this thesis contributes to methods beyond equilibrium statistical mechanics to ultimately understand the nature of the fluid-to-disordered solid transition, or jamming, from a microscopic basis. In Chapter 2 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 instance. Minimal rigidity, however, 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 rules via the Henneberg construction such that these graphs are of the constraint percolation type, where percolation is the study of connected structures in disordered networks. We then probe how jamming graphs destabilize, or become fluid-like, by deleting an edge/contact in the graph and computing the resulting rigid cluster distribution. We also uncover a new potentially diverging lengthscale associated with the random deletion of contacts. In Chapter 3 we study several constraint percolation models, such as k-core percolation and counter-balance percolation, on hyperbolic lattices to better understand the role of loops in such models. The constraints in these percolation models incorporate aspects of local mechanical rigidity found in jammed systems. The expectation is that since these models are indeed easier to analyze than the more

  8. Rigidity of silicone substrates controls cell spreading and stem cell differentiation

    PubMed Central

    Vertelov, Grigory; Gutierrez, Edgar; Lee, Sin-Ae; Ronan, Edward; Groisman, Alex; Tkachenko, Eugene

    2016-01-01

    The dependences of spreading and differentiation of stem cells plated on hydrogel and silicone gel substrates on the rigidity and porosity of the substrates have recently been a subject of some controversy. In experiments on human mesenchymal stem cells plated on soft, medium rigidity, and hard silicone gels we show that harder gels are more osteogenic, softer gels are more adipogenic, and cell spreading areas increase with the silicone gel substrate rigidity. The results of our study indicate that substrate rigidity induces some universal cellular responses independently of the porosity or topography of the substrate. PMID:27651230

  9. Rigidity of silicone substrates controls cell spreading and stem cell differentiation.

    PubMed

    Vertelov, Grigory; Gutierrez, Edgar; Lee, Sin-Ae; Ronan, Edward; Groisman, Alex; Tkachenko, Eugene

    2016-01-01

    The dependences of spreading and differentiation of stem cells plated on hydrogel and silicone gel substrates on the rigidity and porosity of the substrates have recently been a subject of some controversy. In experiments on human mesenchymal stem cells plated on soft, medium rigidity, and hard silicone gels we show that harder gels are more osteogenic, softer gels are more adipogenic, and cell spreading areas increase with the silicone gel substrate rigidity. The results of our study indicate that substrate rigidity induces some universal cellular responses independently of the porosity or topography of the substrate. PMID:27651230

  10. Rigidity of silicone substrates controls cell spreading and stem cell differentiation

    NASA Astrophysics Data System (ADS)

    Vertelov, Grigory; Gutierrez, Edgar; Lee, Sin-Ae; Ronan, Edward; Groisman, Alex; Tkachenko, Eugene

    2016-09-01

    The dependences of spreading and differentiation of stem cells plated on hydrogel and silicone gel substrates on the rigidity and porosity of the substrates have recently been a subject of some controversy. In experiments on human mesenchymal stem cells plated on soft, medium rigidity, and hard silicone gels we show that harder gels are more osteogenic, softer gels are more adipogenic, and cell spreading areas increase with the silicone gel substrate rigidity. The results of our study indicate that substrate rigidity induces some universal cellular responses independently of the porosity or topography of the substrate.

  11. Transport properties of rigid bent-rod macromolecules and of semiflexible broken rods in the rigid-body treatment. Analysis of the flexibility of myosin rod.

    PubMed Central

    Iniesta, A; Díaz, F G; García de la Torre, J

    1988-01-01

    The translational diffusion coefficients, rotational relaxation times and intrinsic viscosities of rigid bent rods, composed by two rodlike arms joined rigidly at an angle alpha, have been evaluated for varying conformation using the latest advances in hydrodynamic theory. We have considered semiflexible rods in which the joint is an elastic hinge or swivel, with a potential V(alpha) = 1/2Q alpha 2 with constant Q. Accepting the rigid-body treatment, we calculate properties of broken rods by averaging alpha-dependent values for rigid rods. The results are finally used to interpret literature values of the properties of myosin rod. Q is regarded as an adjustable parameter, and the value fitted is such that the average bending angle of myosin rod is approximately 60 degrees. PMID:3207825

  12. Development of a sixth-generation down-flow hanging sponge (DHS) reactor using rigid sponge media for post-treatment of UASB treating municipal sewage.

    PubMed

    Onodera, Takashi; Tandukar, Madan; Sugiyana, Doni; Uemura, Shigeki; Ohashi, Akiyoshi; Harada, Hideki

    2014-01-01

    A sixth-generation down-flow hanging sponge reactor (DHS-G6), using rigid sponge media, was developed as a novel aerobic post-treatment unit for upflow anaerobic sludge blanket (UASB) treating municipal sewage. The rigid sponge media were manufactured by copolymerizing polyurethane with epoxy resin. The UASB and DHS system had a hydraulic retention time (HRT) of 10.6 h (8.6 h for UASB and 2 h for DHS) when operated at 10-28 °C. The system gave reasonable organic and nitrogen removal efficiencies. The final effluent had a total biochemical oxygen demand of only 12 mg/L and a total Kjeldahl nitrogen content of 6 mg/L. The DHS reactor gave particularly good nitrification performance, which was attributed to the new rigid sponge media. The sponge media helped to provide a sufficient HRT, and retained a high biomass concentration, extending the solids retention time. The DHS reactor maintained a high dissolved oxygen concentration under natural ventilation.

  13. Material characterization of rigid foam insulation at low temperature

    NASA Astrophysics Data System (ADS)

    Barrios, Matthew

    There is a continuing need for improved rigid foam insulation, particularly for cryogenic storage aboard aerospace vehicles. The present work is a material characterization of spray-on foam insulation used on the Space Shuttle External Tank. The characterization includes imaging and measurements of thermal conductivity, ultimate tensile strength, and moisture absorption. Thermal conductivity measurements are the main focus of the present work, as it is the most relevant property to insulation performance. A novel apparatus was developed to measure the thermal conductivity of rigid foam at temperatures ranging from 20 K to 300 K with a DeltaT of 10 K between the sides of the foam sample. The effective thermal conductivity of three samples of NCFI 24-124 foam insulation was measured over the full temperature range. Additionally, the effects of different residual gases and moisture absorption on the thermal conductivity of the foam were studied. The data were compared to data from the literature and to mathematical models developed to predict the thermal conductivity. The data show that gas condensation can play a significant role in the thermal conductivity of the foam at low temperature. Moisture absorption can occur in the foam in application when cryogenic fuel is filled into a tank which sits in a warm, humid environment. An apparatus was developed to subject foam samples to these conditions. The moisture content in the samples was then measured. The samples were then imaged using the 900 MHz NMR magnet at the National High Magnetic Field Laboratory to determine the location of the water within the foam. Samples conditioned for 9 hours exhibited a 50% weight increase, and samples conditioned for 69 hours exhibited a 284% weight increase. The NMR images showed that the moisture collects first near the warm side of the foam, and permeates through the foam over time. However, the moisture appears to not collect near the knit lines (areas between sprayed layers of

  14. Knowledge of Native Protein-Protein Interfaces Is Sufficient To Construct Predictive Models for the Selection of Binding Candidates.

    PubMed

    Popov, Petr; Grudinin, Sergei

    2015-10-26

    Selection of putative binding poses is a challenging part of virtual screening for protein-protein interactions. Predictive models to filter out binding candidates with the highest binding affinities comprise scoring functions that assign a score to each binding pose. Existing scoring functions are typically deduced by collecting statistical information about interfaces of native conformations of protein complexes along with interfaces of a large generated set of non-native conformations. However, the obtained scoring functions become biased toward the method used to generate the non-native conformations, i.e., they may not recognize near-native interfaces generated with a different method. The present study demonstrates that knowledge of only native protein-protein interfaces is sufficient to construct well-discriminative predictive models for the selection of binding candidates. Here we introduce a new scoring method that comprises a knowledge-based potential called KSENIA deduced from structural information about the native interfaces of 844 crystallographic protein-protein complexes. We derive KSENIA using convex optimization with a training set composed of native protein complexes and their near-native conformations obtained using deformations along the low-frequency normal modes. As a result, our knowledge-based potential has only marginal bias toward a method used to generate putative binding poses. Furthermore, KSENIA is smooth by construction, which allows it to be used along with rigid-body optimization to refine the binding poses. Using several test benchmarks, we demonstrate that our method discriminates well native and near-native conformations of protein complexes from non-native ones. Our methodology can be easily adapted to the recognition of other types of molecular interactions, such as protein-ligand, protein-RNA, etc. KSENIA will be made publicly available as a part of the SAMSON software platform at https://team.inria.fr/nano-d/software . PMID

  15. 30 CFR 7.28 - Test for flame resistance of rigid ventilation tubing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Test for flame resistance of rigid ventilation... and Ventilation Tubing § 7.28 Test for flame resistance of rigid ventilation tubing. (a) Test...) Set the methane-fueled impinged jet burner to yield a flame height of 12 inches as measured at...

  16. 30 CFR 7.28 - Test for flame resistance of rigid ventilation tubing.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Test for flame resistance of rigid ventilation... and Ventilation Tubing § 7.28 Test for flame resistance of rigid ventilation tubing. (a) Test...) Set the methane-fueled impinged jet burner to yield a flame height of 12 inches as measured at...

  17. 30 CFR 7.28 - Test for flame resistance of rigid ventilation tubing.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Test for flame resistance of rigid ventilation... and Ventilation Tubing § 7.28 Test for flame resistance of rigid ventilation tubing. (a) Test...) Set the methane-fueled impinged jet burner to yield a flame height of 12 inches as measured at...

  18. 30 CFR 7.28 - Test for flame resistance of rigid ventilation tubing.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Test for flame resistance of rigid ventilation... and Ventilation Tubing § 7.28 Test for flame resistance of rigid ventilation tubing. (a) Test...) Set the methane-fueled impinged jet burner to yield a flame height of 12 inches as measured at...

  19. Failed fibreoptic intubation: 70° rigid nasendoscope and Frova introducer to the rescue

    PubMed Central

    Vinayagam, Stalin; Prakash, MVS Satya; Kundra, Pankaj; Gopalakrishnan, Surianarayana

    2016-01-01

    Endotracheal intubation was successfully accomplished with 70° rigid nasendoscope under video guidance in two patients in whom repeated attempts to secure airway with flexible fibreoptic bronchoscope were unsuccessful. Both patients had compromised airway (laryngeal papillomatosis and a huge thyroid swelling) and were uncooperative. Frova intubating introducer was used along with 70° rigid nasendoscope to accomplish tracheal intubation under video guidance. PMID:27512168

  20. Fibronectin Rigidity Response through Fyn and p130Cas Recruitment to the Leading Edge

    PubMed Central

    Kostic, Ana

    2006-01-01

    Cell motility on extracellular matrices critically depends on matrix rigidity, which affects cell adhesion and formation of focal contacts. Receptor-like protein tyrosine phosphatase alpha (RPTPα) and the αvβ3 integrin form a rigidity-responsive complex at the leading edge. Here we show that the rigidity response through increased spreading and growth correlates with leading edge recruitment of Fyn, but not endogenous c-Src. Recruitment of Fyn requires the palmitoylation site near the N-terminus and addition of that site to c-Src enables it to support a rigidity response. In all cases, the rigidity response correlates with the recruitment of the Src family kinase to early adhesions. The stretch-activated substrate of Fyn and c-Src, p130Cas, is also required for a rigidity response and it is phosphorylated at the leading edge in a Fyn-dependent process. A possible mechanism for the fibronectin rigidity response involves force-dependent Fyn phosphorylation of p130Cas with rigidity-dependent displacement. With the greater displacement of Fyn from p130Cas on softer surfaces, there will be less phosphorylation. These studies emphasize the importance of force and nanometer-level movements in cell growth and function. PMID:16597701

  1. 21 CFR 177.1010 - Acrylic and modified acrylic plastics, semirigid and rigid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Acrylic and modified acrylic plastics, semirigid... Acrylic and modified acrylic plastics, semirigid and rigid. Semirigid and rigid acrylic and modified acrylic plastics may be safely used as articles intended for use in contact with food, in accordance...

  2. 21 CFR 177.1010 - Acrylic and modified acrylic plastics, semirigid and rigid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Acrylic and modified acrylic plastics, semirigid... Acrylic and modified acrylic plastics, semirigid and rigid. Semirigid and rigid acrylic and modified acrylic plastics may be safely used as articles intended for use in contact with food, in accordance...

  3. 21 CFR 177.1010 - Acrylic and modified acrylic plastics, semirigid and rigid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Acrylic and modified acrylic plastics, semirigid... Acrylic and modified acrylic plastics, semirigid and rigid. Semirigid and rigid acrylic and modified acrylic plastics may be safely used as articles intended for use in contact with food, in accordance...

  4. Reassessment of the risk of healthcare-acquired infection during rigid laryngoscopy.

    PubMed

    Muscarella, L F

    2008-02-01

    Inadequate reprocessing of rigid laryngoscopes has been linked to nosocomial outbreaks with associated morbidity and mortality. Last year an outbreak of Pseudomonas aeruginosa in a neonatal intensive care unit was responsible for multiple infections and colonisations, and at least two infant deaths. An investigation of this outbreak identified contaminated rigid laryngoscopes as its source, demonstrating that inadequate reprocessing of rigid laryngoscopes remains a current public health concern. This article revisits and reassesses the risk of healthcare-acquired infection during rigid laryngoscopy and establishes the minimum reprocessing requirements for blades and handles of rigid laryngoscopes. Several potential risk factors for microbial transmission are identified and discussed, including the publication of inconsistent reprocessing guidelines for rigid laryngoscopes. Concern about guidelines that recommend low-level or intermediate-level disinfection of rigid laryngoscopes is expressed. The use of a sterile disposable sheath to cover the rigid laryngoscope and minimise the risk of contamination is also discussed. Regardless of whether a sheath is used during the procedure, thorough cleaning followed by high-level disinfection and drying of the instrument is recommended to prevent microbial transmission.

  5. A randomised trial of flexible versus rigid nasendoscopy in outpatient sinonasal examination.

    PubMed

    Midwinter, K I; Ahmed, A; Willatt, D

    2001-08-01

    Nasendoscopy is used extensively in ENT clinics both as a diagnostic tool and for local postoperative care. Both flexible and rigid fibreoptic scopes are available for the purpose of sinonasal examination. A prospective study of a flexible versus rigid endoscope was carried out, randomly assigning one type of scope to each nostril of 56 patients presenting to clinic with sinonasal symptomatology. Patients awarded each type of scope a pain score on an analogue scale, according to the level of discomfort experienced, and the operator noted the number of structures seen. Significantly more structures were visualized with the rigid scope than the flexible scope (P = 0.05). The pain scores were similarly in favour of the rigid scope, showing a trend to less discomfort. The rigid nasendoscope is the scope of choice for sinonasal examinations in the outpatient clinic based on these data. PMID:11559337

  6. An incompressible smoothed particle hydrodynamics method for the motion of rigid bodies in fluids

    NASA Astrophysics Data System (ADS)

    Tofighi, N.; Ozbulut, M.; Rahmat, A.; Feng, J. J.; Yildiz, M.

    2015-09-01

    A two-dimensional incompressible smoothed particle hydrodynamics scheme is presented for simulation of rigid bodies moving through Newtonian fluids. The scheme relies on combined usage of the rigidity constraints and the viscous penalty method to simulate rigid body motion. Different viscosity ratios and interpolation schemes are tested by simulating a rigid disc descending in quiescent medium. A viscosity ratio of 100 coupled with weighted harmonic averaging scheme has been found to provide satisfactory results. The performance of the resulting scheme is systematically tested for cases with linear motion, rotational motion and their combination. The test cases include sedimentation of a single and a pair of circular discs, sedimentation of an elliptic disc and migration and rotation of a circular disc in linear shear flow. Comparison with previous results at various Reynolds numbers indicates that the proposed method captures the motion of rigid bodies driven by flow or external body forces accurately.

  7. H infinity controller design to a rigid-flexible satellite with two vibration modes

    NASA Astrophysics Data System (ADS)

    de Souza, A. G.; de Souza, L. C. G.

    2015-10-01

    The satellite attitude control system (ACS) design becomes more complex when the satellite structure has components like, flexible solar panels, antennas and mechanical manipulators. These flexible structures can interact with the satellite rigid parts during translational and/or rotational manoeuvre damaging the ACS pointing accuracy. Although, a well-designed controller can suppress such disturbances quickly, the controller error pointing may be limited by the minimum time necessary to suppress such disturbances thus affecting the satellite attitude acquisition. This paper deals with the rigid-flexible satellite ACS design using the H infinity method. The rigid-flexible satellite is represented by a beam connected to a central rigid hub at one end and free at the other one. The equations of motions are obtained considering small flexible deformations and the Euler-Bernoulli hypothesis. The results of the simulations have shown that the H-infinity controller was able to control the rigid motion and suppress the vibrations.

  8. 3-D rigid body tracking using vision and depth sensors.

    PubMed

    Gedik, O Serdar; Alatan, A Aydn

    2013-10-01

    In robotics and augmented reality applications, model-based 3-D tracking of rigid objects is generally required. With the help of accurate pose estimates, it is required to increase reliability and decrease jitter in total. Among many solutions of pose estimation in the literature, pure vision-based 3-D trackers require either manual initializations or offline training stages. On the other hand, trackers relying on pure depth sensors are not suitable for AR applications. An automated 3-D tracking algorithm, which is based on fusion of vision and depth sensors via extended Kalman filter, is proposed in this paper. A novel measurement-tracking scheme, which is based on estimation of optical flow using intensity and shape index map data of 3-D point cloud, increases 2-D, as well as 3-D, tracking performance significantly. The proposed method requires neither manual initialization of pose nor offline training, while enabling highly accurate 3-D tracking. The accuracy of the proposed method is tested against a number of conventional techniques, and a superior performance is clearly observed in terms of both objectively via error metrics and subjectively for the rendered scenes. PMID:23955795

  9. Homogenization models for thin rigid structured surfaces and films.

    PubMed

    Marigo, Jean-Jacques; Maurel, Agnès

    2016-07-01

    A homogenization method for thin microstructured surfaces and films is presented. In both cases, sound hard materials are considered, associated with Neumann boundary conditions and the wave equation in the time domain is examined. For a structured surface, a boundary condition is obtained on an equivalent flat wall, which links the acoustic velocity to its normal and tangential derivatives (of the Myers type). For a structured film, jump conditions are obtained for the acoustic pressure and the normal velocity across an equivalent interface (of the Ventcels type). This interface homogenization is based on a matched asymptotic expansion technique, and differs slightly from the classical homogenization, which is known to fail for small structuration thicknesses. In order to get insight into what causes this failure, a two-step homogenization is proposed, mixing classical homogenization and matched asymptotic expansion. Results of the two homogenizations are analyzed in light of the associated elementary problems, which correspond to problems of fluid mechanics, namely, potential flows around rigid obstacles. PMID:27475151

  10. Knowledge-i-action: an example with rigid body motion

    NASA Astrophysics Data System (ADS)

    Salvador Cabral da Costa, Sayonara; 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 Pontifícia Universidade Católica 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-Laird’s mental models theory and Vergnaud’s conceptual fields theory. The problem-solving process has been investigated from the presentation of the problems’ variables and the pictures that followed it, up to the resolution itself. This investigation was carried out by analysing the knowledge-in-action that students have used as inferred from their written solutions and from what they said in semi-structured interviews. The findings of this analysis identified some characteristics in their answers that may help us to understand the processes used by students during the problem-solving task, with possible consequences for classroom procedures used by teachers.

  11. Local Study of Flexural Rigidity in Old Oceanic Lithosphere

    NASA Astrophysics Data System (ADS)

    Ramirez, C.; Weeraratne, D. S.; Forsyth, D. W.

    2010-12-01

    The half-space cooling model predicts lithosphere thickness and that the depth of the sea floor should increase in proportion to the square root of age due to conductive cooling. For seafloor greater than 70 Ma the seafloor is shallower than the square-root-of-age trend, but global seismic tomography studies are in rough agreement with the half-space cooling model. We conducted a marine bathymetry and seismic study in the western Pacific south of the Shatsky Rise on seafloor ~150 Ma to study this discrepancy. The field area is located at a fossil triple junction straddling a magnetic bight. Several small seamounts located in the study area with excellent bathymetric coverage are surrounded by clear flexural moats. The characteristic wavelength of the flexure indicates that the effective elastic thickness, Te is less than 2 km, suggesting that these seamounts were formed on very young seafloor close to the spreading center 150 My ago. Larger seamounts in the study area appear to have formed later off-axis. We will present admittance results to determine the rigidity and Te of the plate at the time of loading of this later episode of volcanism. These measurements will provide us with a better understanding of how oceanic lithosphere and asthenosphere grow and interact in both time and space.

  12. Weak hydrogen bonding yields rigid, tough, and elastic hydrogels

    NASA Astrophysics Data System (ADS)

    Sheiko, Sergei; Hu, Xiaobo; Vatankhah-Varnosfaderani, Mohammad; Zhou, Jing; Li, Qiaoxi; Dobrynin, Andrey

    Unlike living tissues, synthetic hydrogels are inherently soft and brittle, particularly when built of hydrogen bonds. It remains challenging to design hydrogels that combine high rigidity, strength at break, extensibility, high elasticity. Through free-radical copolymerization of N , N -dimethylacrylamide and methacrylic acid, we have designed a network system based on tunable composition of covalent bonds (permanent cross-links) and hydrogen bonds (sacrificial and recoverable crosslinks) with the following rationale: 1) Maintain a high total number of cross-links to ensure high modulus; 2) Introduce a high fraction of H-bonding to ensure high energy dissipation; and 3) Incorporate a small fraction of permanent cross-links to ensure shape control. By tuning the chemical composition and microstructure we have obtained materials with superb mechanical properties. The hydrogels contain 70 wt% water (similar to living cartilage, skin, and ligaments), while display modulus of 28 MPa, strength of 2 MPa, fracture energy of 9300 J .m-2, extensibility of 800%, excellent fatigue-resistance, and great elasticity allowing for complete and fast strain recovery. The results agreed with theoretical predictions for modulus relaxation of dual networks with dynamic and permanent crosslinks. We gratefully acknowledge funding from the National Science Foundation (DMR 1122483, DMR 1407645, and DMR 1436201).

  13. 3-D rigid body tracking using vision and depth sensors.

    PubMed

    Gedik, O Serdar; Alatan, A Aydn

    2013-10-01

    In robotics and augmented reality applications, model-based 3-D tracking of rigid objects is generally required. With the help of accurate pose estimates, it is required to increase reliability and decrease jitter in total. Among many solutions of pose estimation in the literature, pure vision-based 3-D trackers require either manual initializations or offline training stages. On the other hand, trackers relying on pure depth sensors are not suitable for AR applications. An automated 3-D tracking algorithm, which is based on fusion of vision and depth sensors via extended Kalman filter, is proposed in this paper. A novel measurement-tracking scheme, which is based on estimation of optical flow using intensity and shape index map data of 3-D point cloud, increases 2-D, as well as 3-D, tracking performance significantly. The proposed method requires neither manual initialization of pose nor offline training, while enabling highly accurate 3-D tracking. The accuracy of the proposed method is tested against a number of conventional techniques, and a superior performance is clearly observed in terms of both objectively via error metrics and subjectively for the rendered scenes.

  14. Rigid and high NA multiphoton fluorescence GRIN-endoscopes

    NASA Astrophysics Data System (ADS)

    Schenkl, Selma; Ehlers, Alexander; Le Harzic, Ronan; Stark, Martin; Riemann, Iris; Messerschmidt, Bernhard; Kaatz, Martin; König, Karsten

    2007-07-01

    Multiphoton autofluorescence imaging offers minimal-invasive examination of cells without the need of staining and complicated confocal detection systems. Therefore, it is especially interesting for non-invasive clinical diagnostics. To extend this sophisticated technique from superficial regions to deep lying cell layers, internal body parts and specimens difficult of access, the bulky optics need to be reduced in diameter. This is done by tiny GRIN-optics, based on a radial gradient in the reflective index. Of especial interest for multi-photon applications is the newly developed GRIN-lens assembly with increased numerical aperture. High resolution images of plant tissue, hair and cells show the improved image quality,compared to classical GRIN-lenses. The rigid GRIN-endoscopes are already applied in wound healing studies. Here, the GRIN-lenses with diameters smaller than 3 mm enter small skin depressions. They reproduce the focus of a conventional laser scanning tomograph tens of mm apart in the specimen under study. We present first clinical measurements of elastin and SHG of collagen of in-vivo human skin of venous ulcers (ulcer curis).

  15. Non-rigid registration of cervical spine MRI volumes.

    PubMed

    Aktar, Mst Nargis; Alam, Md Jahangir; Pickering, Mark; Webb, Alexandra; Perriman, Diana

    2015-08-01

    Whiplash is the colloquial term for neck injuries caused by sudden extension of the cervical spine. Patients with chronic whiplash associated disorder (WAD) can experience neck pain for many years after the original injury. Researchers have found some evidence to suggest that chronic whiplash is related to the amount of intra-muscular fat in the cervical spine muscles. Hence, an important step towards developing a treatment for chronic WAD is a technique to accurately and efficiently measure the amount of intra-muscular fat in the muscles of the cervical spine. Our proposed technique for making this measurement is to automatically segment the cervical spine muscles using a fused volume created from multi-modal MRI volumes of the cervical spine. Multiple modes are required to enhance the boundaries between the different muscles to assist the following automatic segmentation process. However, before these multiple modes can be fused it is first necessary to accurately register these volumes. Hence, in this paper, we have proposed a new non-rigid multi-modal registration algorithm using the sum of conditional variance (SCV) with partial volume interpolation (PVI) similarity measure and Gauss-Newton (GN) optimization for the accurate registration of multi-modal cervical spine MRI volumes. The performance of the proposed approach is compared with the existing SCV based registration algorithm and the sum of the conditional squared deviation from the mode (SCSDM) method. The experimental results demonstrate that the proposed approach provides superior performance than the best existing approaches. PMID:26736677

  16. Compaction around a rigid, circular inclusion in partially molten rock

    NASA Astrophysics Data System (ADS)

    Alisic, Laura; Rudge, John F.; Katz, Richard F.; Wells, Garth N.; Rhebergen, Sander

    2014-07-01

    Conservation laws that describe the behavior of partially molten mantle rock have been established for several decades, but the associated rheology remains poorly understood. Constraints on the rheology may be obtained from recently published experiments involving deformation of partially molten rock around a rigid, spherical inclusion. These experiments give rise to patterns of melt segregation that exhibit the competing effects of pressure shadows and melt-rich bands. Such patterns provide an opportunity to infer rheological parameters through comparison with models based on the conservation laws and constitutive relations that hypothetically govern the system. To this end, we have developed software tools to simulate finite strain, two-phase flow around a circular inclusion in a configuration that mirrors the experiments. Simulations indicate that the evolution of porosity is predominantly controlled by the porosity-weakening exponent of the shear viscosity and the poorly known bulk viscosity. In two-dimensional simulations presented here, we find that the balance of pressure shadows and melt-rich bands observed in experiments only occurs for bulk-to-shear viscosity ratio of less than about five. However, the evolution of porosity in simulations with such low bulk viscosity exceeds physical bounds at unrealistically small strain due to the unchecked, exponential growth of the porosity variations. Processes that limit or balance porosity localization should be incorporated in the formulation of the model to produce results that are consistent with the porosity evolution in experiments.

  17. Rigid-body molecular dynamics of DNA inside a nucleosome.

    PubMed

    Fathizadeh, Arman; Berdy Besya, Azim; Reza Ejtehadi, Mohammad; Schiessel, Helmut

    2013-03-01

    The majority of eukaryotic DNA, about three quarter, is wrapped around histone proteins forming so-called nucleosomes. To study nucleosomal DNA we introduce a coarse-grained molecular dynamics model based on sequence-dependent harmonic rigid base pair step parameters of DNA and nucleosomal binding sites. Mixed parametrization based on all-atom molecular dynamics and crystallographic data of protein-DNA structures is used for the base pair step parameters. The binding site parameters are adjusted by experimental B-factor values of the nucleosome crystal structure. The model is then used to determine the energy cost for placing a twist defect into the nucleosomal DNA which allows us to use Kramers theory to calculate nucleosome sliding caused by such defects. It is shown that the twist defect scenario together with the sequence-dependent elasticity of DNA can explain the slow time scales observed for nucleosome mobility along DNA. With this method we also show how the twist defect mechanism leads to a higher mobility of DNA in the presence of sin mutations near the dyad axis. Finally, by performing simulations on 5s rDNA, 601, and telomeric base pair sequences, it is demonstrated that the current model is a powerful tool to predict nucleosome positioning. PMID:23475204

  18. [The development of gender identity beyond rigid dichotomy].

    PubMed

    Quindeau, Ilka

    2014-01-01

    The conflicts individuals with ambiguous sexual characteristics suffer from are not the result of genetic features but of the rigid and dichotomous gender order, which is currently undergoing a renaissance. This also applies to individuals with an uncertain gender identity. In the best interests of the child a concept of gender seems necessary, that goes beyond a binary separation and allows gender-specific intermediary stages in the personal development of identity. Such a gender concept can be developed following psychoanalytic theories. The present discourse contains a scale of connecting factors for a differentiated and less normative conceptualization of gender development. Starting from Freud's concept of constitutional bisexuality, Robert Stoller's theory, which has been firmly rooted in the mainstream of psychoanalysis for more than 40 years, will be critically reviewed. By involving Reimut Reiche's and Jean Laplanche's arguments, a continuative psychological gender theory will be drafted, which does not normatively and reductively claim the demarcation of gender, but rather opens up a space for gender diversity. PMID:25296507

  19. Enzyme surface rigidity tunes the temperature dependence of catalytic rates.

    PubMed

    Isaksen, Geir Villy; Åqvist, Johan; Brandsdal, Bjørn Olav

    2016-07-12

    The structural origin of enzyme adaptation to low temperature, allowing efficient catalysis of chemical reactions even near the freezing point of water, remains a fundamental puzzle in biocatalysis. A remarkable universal fingerprint shared by all cold-active enzymes is a reduction of the activation enthalpy accompanied by a more negative entropy, which alleviates the exponential decrease in chemical reaction rates caused by lowering of the temperature. Herein, we explore the role of protein surface mobility in determining this enthalpy-entropy balance. The effects of modifying surface rigidity in cold- and warm-active trypsins are demonstrated here by calculation of high-precision Arrhenius plots and thermodynamic activation parameters for the peptide hydrolysis reaction, using extensive computer simulations. The protein surface flexibility is systematically varied by applying positional restraints, causing the remarkable effect of turning the cold-active trypsin into a variant with mesophilic characteristics without changing the amino acid sequence. Furthermore, we show that just restraining a key surface loop causes the same effect as a point mutation in that loop between the cold- and warm-active trypsin. Importantly, changes in the activation enthalpy-entropy balance of up to 10 kcal/mol are almost perfectly balanced at room temperature, whereas they yield significantly higher rates at low temperatures for the cold-adapted enzyme.

  20. Rigid Polyurethane Foams from Lignin Based-Polyols

    NASA Astrophysics Data System (ADS)

    Cateto, Carolina; Barreiro, Filomena; Rodrigues, Alírio; Belgacem, Naceur

    2008-08-01

    Rigid polyurethane (RPU) foams were synthesized using lignin-based polyols obtained by an oxypropylation process. Alcell, Indulin AT, Curan 27-11P and Sarkanda lignins have been oxypropylated using formulations deduced from an optimization study with Alcell. L/PO/C (ratio between lignin, PO and catalyst content) of 30/70/2 and 20/80/5 were used to obtain the desired polyols. The resulting RPU foams were characterized in terms of density, mechanical properties, conductivity and morphology. All Sarkanda lignin based polyols and the 30/70/2 Curan 27-11P polyol were found inadequate for RPU formulations. Alcell and Indulin AT based polyols and the 20/80/5 Curan 27-11P polyol resulted in RPU foams with properties very similar to those obtained from conventional commercial polyols. RPU foams produced with the 30/70/2 Alcell and the 30/70/2 Indulin AT polyols exhibited improved properties compared with those from 20/80/5 based formulations.

  1. Enzyme surface rigidity tunes the temperature dependence of catalytic rates.

    PubMed

    Isaksen, Geir Villy; Åqvist, Johan; Brandsdal, Bjørn Olav

    2016-07-12

    The structural origin of enzyme adaptation to low temperature, allowing efficient catalysis of chemical reactions even near the freezing point of water, remains a fundamental puzzle in biocatalysis. A remarkable universal fingerprint shared by all cold-active enzymes is a reduction of the activation enthalpy accompanied by a more negative entropy, which alleviates the exponential decrease in chemical reaction rates caused by lowering of the temperature. Herein, we explore the role of protein surface mobility in determining this enthalpy-entropy balance. The effects of modifying surface rigidity in cold- and warm-active trypsins are demonstrated here by calculation of high-precision Arrhenius plots and thermodynamic activation parameters for the peptide hydrolysis reaction, using extensive computer simulations. The protein surface flexibility is systematically varied by applying positional restraints, causing the remarkable effect of turning the cold-active trypsin into a variant with mesophilic characteristics without changing the amino acid sequence. Furthermore, we show that just restraining a key surface loop causes the same effect as a point mutation in that loop between the cold- and warm-active trypsin. Importantly, changes in the activation enthalpy-entropy balance of up to 10 kcal/mol are almost perfectly balanced at room temperature, whereas they yield significantly higher rates at low temperatures for the cold-adapted enzyme. PMID:27354533

  2. On removing interpolation and resampling artifacts in rigid image registration.

    PubMed

    Aganj, Iman; Yeo, Boon Thye Thomas; Sabuncu, Mert R; Fischl, Bruce

    2013-02-01

    We show that image registration using conventional interpolation and summation approximations of continuous integrals can generally fail because of resampling artifacts. These artifacts negatively affect the accuracy of registration by producing local optima, altering the gradient, shifting the global optimum, and making rigid registration asymmetric. In this paper, after an extensive literature review, we demonstrate the causes of the artifacts by comparing inclusion and avoidance of resampling analytically. We show the sum-of-squared-differences cost function formulated as an integral to be more accurate compared with its traditional sum form in a simple case of image registration. We then discuss aliasing that occurs in rotation, which is due to the fact that an image represented in the Cartesian grid is sampled with different rates in different directions, and propose the use of oscillatory isotropic interpolation kernels, which allow better recovery of true global optima by overcoming this type of aliasing. Through our experiments on brain, fingerprint, and white noise images, we illustrate the superior performance of the integral registration cost function in both the Cartesian and spherical coordinates, and also validate the introduced radial interpolation kernel by demonstrating the improvement in registration.

  3. Enzyme surface rigidity tunes the temperature dependence of catalytic rates

    PubMed Central

    Isaksen, Geir Villy; Åqvist, Johan; Brandsdal, Bjørn Olav

    2016-01-01

    The structural origin of enzyme adaptation to low temperature, allowing efficient catalysis of chemical reactions even near the freezing point of water, remains a fundamental puzzle in biocatalysis. A remarkable universal fingerprint shared by all cold-active enzymes is a reduction of the activation enthalpy accompanied by a more negative entropy, which alleviates the exponential decrease in chemical reaction rates caused by lowering of the temperature. Herein, we explore the role of protein surface mobility in determining this enthalpy–entropy balance. The effects of modifying surface rigidity in cold- and warm-active trypsins are demonstrated here by calculation of high-precision Arrhenius plots and thermodynamic activation parameters for the peptide hydrolysis reaction, using extensive computer simulations. The protein surface flexibility is systematically varied by applying positional restraints, causing the remarkable effect of turning the cold-active trypsin into a variant with mesophilic characteristics without changing the amino acid sequence. Furthermore, we show that just restraining a key surface loop causes the same effect as a point mutation in that loop between the cold- and warm-active trypsin. Importantly, changes in the activation enthalpy–entropy balance of up to 10 kcal/mol are almost perfectly balanced at room temperature, whereas they yield significantly higher rates at low temperatures for the cold-adapted enzyme. PMID:27354533

  4. Dynamical analysis of an orbiting three-rigid-body system

    SciTech Connect

    Pagnozzi, Daniele E-mail: james.biggs@strath.ac.uk; Biggs, James D. E-mail: james.biggs@strath.ac.uk

    2014-12-10

    The development of multi-joint-spacecraft mission concepts calls for a deeper understanding of their nonlinear dynamics to inform and enhance system design. This paper presents a study of a three-finite-shape rigid-body system under the action of an ideal central gravitational field. The aim of this paper is to gain an insight into the natural dynamics of this system. The Hamiltonian dynamics is derived and used to identify relative attitude equilibria of the system with respect to the orbital reference frame. Then a numerical investigation of the behaviour far from the equilibria is provided using tools from modern dynamical systems theory such as energy methods, phase portraits and Poincarè maps. Results reveal a complex structure of the dynamics as well as the existence of connections between some of the equilibria. Stable equilibrium configurations appear to be surrounded by very narrow regions of regular and quasi-regular motions. Trajectories evolve on chaotic motions in the rest of the domain.

  5. Homogenization models for thin rigid structured surfaces and films.

    PubMed

    Marigo, Jean-Jacques; Maurel, Agnès

    2016-07-01

    A homogenization method for thin microstructured surfaces and films is presented. In both cases, sound hard materials are considered, associated with Neumann boundary conditions and the wave equation in the time domain is examined. For a structured surface, a boundary condition is obtained on an equivalent flat wall, which links the acoustic velocity to its normal and tangential derivatives (of the Myers type). For a structured film, jump conditions are obtained for the acoustic pressure and the normal velocity across an equivalent interface (of the Ventcels type). This interface homogenization is based on a matched asymptotic expansion technique, and differs slightly from the classical homogenization, which is known to fail for small structuration thicknesses. In order to get insight into what causes this failure, a two-step homogenization is proposed, mixing classical homogenization and matched asymptotic expansion. Results of the two homogenizations are analyzed in light of the associated elementary problems, which correspond to problems of fluid mechanics, namely, potential flows around rigid obstacles.

  6. [The development of gender identity beyond rigid dichotomy].

    PubMed

    Quindeau, Ilka

    2014-01-01

    The conflicts individuals with ambiguous sexual characteristics suffer from are not the result of genetic features but of the rigid and dichotomous gender order, which is currently undergoing a renaissance. This also applies to individuals with an uncertain gender identity. In the best interests of the child a concept of gender seems necessary, that goes beyond a binary separation and allows gender-specific intermediary stages in the personal development of identity. Such a gender concept can be developed following psychoanalytic theories. The present discourse contains a scale of connecting factors for a differentiated and less normative conceptualization of gender development. Starting from Freud's concept of constitutional bisexuality, Robert Stoller's theory, which has been firmly rooted in the mainstream of psychoanalysis for more than 40 years, will be critically reviewed. By involving Reimut Reiche's and Jean Laplanche's arguments, a continuative psychological gender theory will be drafted, which does not normatively and reductively claim the demarcation of gender, but rather opens up a space for gender diversity.

  7. Interpenetration free simulation of thin shell rigid bodies.

    PubMed

    English, R Elliot; Lentine, Michael; Fedkiw, Ron

    2013-06-01

    We propose a new algorithm for rigid body simulation that guarantees each body is in an interpenetration free state, both increasing the accuracy and robustness of the simulation as well as alleviating the need for ad hoc methods to separate bodies for subsequent simulation and rendering. We cleanly separate collision and contact resolution such that objects move and collide in the first step, with resting contact handled in the second step. The first step of our algorithm guarantees that each time step produces geometry that does not intersect or overlap by using an approximation to the continuous collision detection (and response) problem and, thus, is amenable to thin shells and degenerately flat objects moving at high speeds. In addition, we introduce a novel fail-safe that allows us to resolve all interpenetration without iterating to convergence. Since the first step guarantees a noninterfering state for the geometry, in the second step we propose a contact model for handling thin shells in proximity considering only the instantaneous locations at the ends of the time step. PMID:23559511

  8. Reversible rigid coupling apparatus and method for borehole seismic transducers

    DOEpatents

    Owen, Thomas E.; Parra, Jorge O.

    1992-01-01

    An apparatus and method of high resolution reverse vertical seismic profile (VSP) measurements is shown. By encapsulating the seismic detector and heaters in a meltable substance (such as wax), the seismic detector can be removably secured in a borehole in a manner capable of measuring high resolution signals in the 100 to 1000 hertz range and higher. The meltable substance is selected to match the overall density of the detector package with the underground formation, yet still have relatively low melting point and rigid enough to transmit vibrations to accelerometers in the seismic detector. To minimize voids in the meltable substance upon solidification, the meltable substance is selected for minimum shrinkage, yet still having the other desirable characteristics. Heaters are arranged in the meltable substance in such a manner to allow the lowermost portion of the meltable substance to cool and solidify first. Solidification continues upwards from bottom-to-top until the top of the meltable substance is solidified and the seismic detector is ready for use. To remove, the heaters melt the meltable substance and the detector package is pulled from the borehole.

  9. Modeling rigid magnetically rotated microswimmers: Rotation axes, bistability, and controllability

    NASA Astrophysics Data System (ADS)

    Meshkati, Farshad; Fu, Henry Chien

    2014-12-01

    Magnetically actuated microswimmers have recently attracted attention due to many possible biomedical applications. In this study we investigate the dynamics of rigid magnetically rotated microswimmers with permanent magnetic dipoles. Our approach uses a boundary element method to calculate a mobility matrix, accurate for arbitrary geometries, which is then used to identify the steady periodically rotating orbits in a co-rotating body-fixed frame. We evaluate the stability of each of these orbits. We map the magnetoviscous behavior as a function of dimensionless Mason number and as a function of the angle that the magnetic field makes with its rotation axis. We describe the wobbling motion of these swimmers by investigating how the rotation axis changes as a function of experimental parameters. We show that for a given magnetic field strength and rotation frequency, swimmers can have more than one stable periodic orbit with different rotation axes. Finally, we demonstrate that one can improve the controllability of these types of microswimmers by adjusting the relative angle between the magnetic field and its axis of rotation.

  10. Dorsal Hippocampal CREB Is Both Necessary and Sufficient for Spatial Memory

    ERIC Educational Resources Information Center

    Sekeres, Melanie J.; Neve, Rachael L.; Frankland, Paul W.; Josselyn, Sheena A.

    2010-01-01

    Although the transcription factor CREB has been widely implicated in memory, whether it is sufficient to produce spatial memory under conditions that do not normally support memory formation in mammals is unknown. We found that locally and acutely increasing CREB levels in the dorsal hippocampus using viral vectors is sufficient to induce robust…

  11. 33 CFR 115.30 - Sufficiency of State authority for bridges.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... for bridges. 115.30 Section 115.30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES § 115.30 Sufficiency of State authority for bridges. An opinion of the attorney general of the State as to the sufficiency of...

  12. 33 CFR 115.30 - Sufficiency of State authority for bridges.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... for bridges. 115.30 Section 115.30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES § 115.30 Sufficiency of State authority for bridges. An opinion of the attorney general of the State as to the sufficiency of...

  13. 33 CFR 115.30 - Sufficiency of State authority for bridges.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... for bridges. 115.30 Section 115.30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES § 115.30 Sufficiency of State authority for bridges. An opinion of the attorney general of the State as to the sufficiency of...

  14. 33 CFR 115.30 - Sufficiency of State authority for bridges.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... for bridges. 115.30 Section 115.30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES § 115.30 Sufficiency of State authority for bridges. An opinion of the attorney general of the State as to the sufficiency of...

  15. 33 CFR 115.30 - Sufficiency of State authority for bridges.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... for bridges. 115.30 Section 115.30 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES § 115.30 Sufficiency of State authority for bridges. An opinion of the attorney general of the State as to the sufficiency of...

  16. 29 CFR 780.513 - What employment in growing and harvesting is sufficient.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... qualifying for this exemption even if in some past season he was employed in growing and harvesting such... 29 Labor 3 2010-07-01 2010-07-01 false What employment in growing and harvesting is sufficient....513 What employment in growing and harvesting is sufficient. To qualify for exemption the...

  17. 29 CFR 780.513 - What employment in growing and harvesting is sufficient.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... qualifying for this exemption even if in some past season he was employed in growing and harvesting such... 29 Labor 3 2014-07-01 2014-07-01 false What employment in growing and harvesting is sufficient....513 What employment in growing and harvesting is sufficient. To qualify for exemption the...

  18. 29 CFR 780.513 - What employment in growing and harvesting is sufficient.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... qualifying for this exemption even if in some past season he was employed in growing and harvesting such... 29 Labor 3 2013-07-01 2013-07-01 false What employment in growing and harvesting is sufficient....513 What employment in growing and harvesting is sufficient. To qualify for exemption the...

  19. 29 CFR 780.513 - What employment in growing and harvesting is sufficient.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... qualifying for this exemption even if in some past season he was employed in growing and harvesting such... 29 Labor 3 2012-07-01 2012-07-01 false What employment in growing and harvesting is sufficient....513 What employment in growing and harvesting is sufficient. To qualify for exemption the...

  20. 29 CFR 780.513 - What employment in growing and harvesting is sufficient.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... qualifying for this exemption even if in some past season he was employed in growing and harvesting such... 29 Labor 3 2011-07-01 2011-07-01 false What employment in growing and harvesting is sufficient....513 What employment in growing and harvesting is sufficient. To qualify for exemption the...