Probing the E2 properties of the scissors mode with real photons

NASA Astrophysics Data System (ADS)

Beck, Tobias; Pietralla, Norbert; Beller, Jacob; Derya, Vera; Löher, Bastian; Savran, Deniz; Tornow, Werner; Werner, Volker; Zilges, Andreas

2018-05-01

The E2/M1 multipole mixing ratio δ1→2 of the 1+ sc → 2+ 1 γ-ray transition of 156Gd and 164Dy has been measured using the linearly polarized photon beams of the HIγS facility. The employed method of photonscattering experiments in combination with polarized, quasi-monochromatic beams and a dedicated detector setup is highly sensitive to the electric quadrupole-decay properties of the scissors mode.

Teleporting photonic qudits using multimode quantum scissors.

PubMed

Goyal, Sandeep K; Konrad, Thomas

2013-12-19

Teleportation plays an important role in the communication of quantum information between the nodes of a quantum network and is viewed as an essential ingredient for long-distance Quantum Cryptography. We describe a method to teleport the quantum information carried by a photon in a superposition of a number d of light modes (a "qudit") by the help of d additional photons based on transcription. A qudit encoded into a single excitation of d light modes (in our case Laguerre-Gauss modes which carry orbital angular momentum) is transcribed to d single-rail photonic qubits, which are spatially separated. Each single-rail qubit consists of a superposition of vacuum and a single photon in each one of the modes. After successful teleportation of each of the d single-rail qubits by means of "quantum scissors" they are converted back into a qudit carried by a single photon which completes the teleportation scheme.

Teleporting photonic qudits using multimode quantum scissors

NASA Astrophysics Data System (ADS)

Goyal, Sandeep K.; Konrad, Thomas

2013-12-01

Teleportation plays an important role in the communication of quantum information between the nodes of a quantum network and is viewed as an essential ingredient for long-distance Quantum Cryptography. We describe a method to teleport the quantum information carried by a photon in a superposition of a number d of light modes (a ``qudit'') by the help of d additional photons based on transcription. A qudit encoded into a single excitation of d light modes (in our case Laguerre-Gauss modes which carry orbital angular momentum) is transcribed to d single-rail photonic qubits, which are spatially separated. Each single-rail qubit consists of a superposition of vacuum and a single photon in each one of the modes. After successful teleportation of each of the d single-rail qubits by means of ``quantum scissors'' they are converted back into a qudit carried by a single photon which completes the teleportation scheme.

Are the low-lying isovector 1 + states scissors vibrations?

NASA Astrophysics Data System (ADS)

Faessler, A.

At the Technische Hochschule in Darmstadt the group of Richter and coworkers found in 1983/84 in deformed rare earth nuclei low-lying isovector 1 + states. Such states have been predicted in the generalized Bohr-Mottelson model and in the interacting boson model no. 2 (IBA2). In the generalized Bohr-Mottelson model one allows for proton and neutron quadrupole deformations separately. If one includes only static proton and neutron deformations the generalized Bohr-Mottelson model reduces to the two rotor model. It describes the excitation energy of these states in good agreement with the data but overestimates the magnetic dipole transition probabilities by a factor 5. In the interacting boson model (IBA2) where only the outermost nucleons participate in the excitation the magnetic dipole transition probability is only overestimated by a factor 2. The too large collectivity in both models results from the fact that they concentrate the whole strength of the scissors vibrations into one state. A microscopic description is needed to describe the spreading of the scissors strength over several states. For a microscopic determination of these scissors states one uses the Quasi-particle Random Phase Approximation (QRPA). But this approach has a serious difficulty. Since one rotates for the calculation the nucleus into the intrinsic system the state corresponding to the rotation of the whole nucleus is a spurious state. The usual procedure to remove this spuriosity is to use the Thouless theorem which says that a spurious state created by an operator which commutes with the total hamiltonian (here the total angular momentum, corresponding to a rotation of the whole system) produces the spurious state if applied to the ground state. It says further the energy of this spurious state lies at zero excitation energy (it is degenerate with the ground state) and is orthogonal to all physical states. Thus the usual approach is to vary the quadrupole-quadrupole force strength so that a state lies at zero excitation energy and to identify that with the spuríous state. This procedure assumes that a total angular momentum commutes with a total hamiltonian. But this is not the case since the total hamiltonian contains a deformed Saxon-Woods potential. Thus one has to take care explicitly that the spurious state is removed. This we do in our approach by introducing Lagrange multipliers for each excited states and requesting that these states are orthogonal to the spurious state which is explicitly constructed by applying the total angular momentum operator to the ground state. To reduce the number of free parameters in the hamiltonian we take the Saxon-Woods potential for the deformed nuclei from the literature (with minor adjustments) and determine the proton-proton, neutron-neutron and the proton-neutron quadrupole force constant by requesting that the hamiltonian commutes with the total angular momentum in the (QRPA) ground state. This yields equations fixing all three coupling constants for the quadrupole-quadrupole force allowing even for isospin symmetry violation. The spin-spin force is taken from the Reid soft core potential. A possible spin-quadrupole force has been taken from the work of Soloviev but it turns out that this is not important. The calculation shows that the strength of the scissors vibrations are spread over many states. The main 1 + state at around 3 MeV has an overlap of the order of 14 % of the scissors state. 50% of that state are spread over the physical states up to an excitation energy of 6 MeV. The rest is distributed over higher lying states. The expectation value of the many-body hamiltonian in the scissors vibrational state shows roughly an excitation energy of 7 MeV above the ground state. The results also support the experimental findings that these states are mainly orbital excitations. States are not very collective. Normally only a proton and neutron particle-hole pair are with a large amplitude participating in forming these states. But those protons and neutrons which are excited perform scissors type vibrations.

Scissors Modes and Spin Excitations in Light Nuclei Including ΔN=2 Excitations: Behaviour of 8Be and 10Be

NASA Astrophysics Data System (ADS)

Fayache, M. S.; Sharma, S. Shelley; Zamick, L.

1996-10-01

Shell model calculations are performed for magnetic dipole excitations in8Be and10Be, first with a quadrupole-quadrupole interaction (Q·Q) and then with a realistic interaction. The calculations are performed both in a 0pspace and in a large space which includes all 2ℏωexcitations. In the 0pwithQ·Qwe have an analytic expression for the energies of all states. In this limit we find that in10Be theL=1S=0 scissors mode with isospinT=1 is degenerate with that ofT=2. By projection from an intrinsic state we can obtain simple expressions forB(M1) to the scissors modes in8Be and10Be. We plot cumulative sums for energy-weighted isovector orbital transitions fromJ=0+ground states to the 1+excited states. These have the structure of a low-energy plateau and a steep rise to a high-energy plateau. The relative magnitudes of these plateaux are discussed. By comparing8Be and10Be we find that contrary to the behaviour in heavy deformed nuclei,B(M1)orbitalis not proportional toB(E2). On the other hand, a sum rule which relatesB(M1) to the difference (B(E2)isoscalar-B(E2)isovector) succeeds in describing the difference in behaviours in the two nuclei. The results forQ·Qand the realistic interactions are compared, as are the results in the 0pspace and the large (0p+2ℏω) space. The Wigner supermultiplet scheme is a very useful guide in analyzing the shell model results.

Hydrogen bonds in betaine-acid (1:1) crystals revealed by Raman and 13C chemical shift tensors

NASA Astrophysics Data System (ADS)

Ilczyszyn, Marek; Ilczyszyn, Maria M.

2017-06-01

H-bonds of five betaine-acid (1:1) crystals are considered by analysis of tensors based on the Raman scissoring mode and 13C chemical shift of the betaine -CO1O2- carboxylate group. The leading structural factor in these systems is the strongest H-bond linking the betaine and the acidic moieties, (O1⋯H-O)com. The Raman and NMR tensors are strongly related to its character and to the R(O1⋯O)com distance. Very high molecular polarizability variation due to the scissoring vibration was found for the betaine-selenious acid crystal. The probable reason is modest network of H-bonds in this case and relatively high proton polarizability of these bonds.

21 CFR 880.6820 - Medical disposable scissors.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Medical disposable scissors. 880.6820 Section 880...) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Miscellaneous Devices § 880.6820 Medical disposable scissors. (a) Identification. Medical disposable scissors are...

21 CFR 880.6820 - Medical disposable scissors.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical disposable scissors. 880.6820 Section 880...) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Miscellaneous Devices § 880.6820 Medical disposable scissors. (a) Identification. Medical disposable scissors are...

Ergonomic design and evaluation of new surgical scissors.

PubMed

Shimomura, Yoshihiro; Shirakawa, Hironori; Sekine, Masashi; Katsuura, Tetsuo; Igarashi, Tatsuo

2015-01-01

The purpose of this study is to design a new surgical scissors handle and determine its effectiveness with various usability indices. A new scissors handle was designed that retains the professional grip but has the shapes of the eye rings modified to fit the thumb and ring finger and finger rests for the index and little finger. The newly designed scissors and traditional scissors were compared by electromyography, subjective evaluation and task performance in experiments using cutting and peeling tasks. The newly designed scissors reduced muscle load in both hand during cutting by the closing action, and reduced the muscle load in the left hand during peeling by the opening action through active use of the right hand. In evaluation by surgeons, task performance improved in addition to the decrease in muscle load. The newly designed scissors used in this study demonstrated high usability. A new scissors handle was designed that has the eye rings modified to fit the thumb and ring finger. The newly designed scissors reduced muscle load and enabled active use of the right hand. In evaluation by surgeons, task performance improved in addition to the decrease in muscle load.

Study of the Photon Strength Functions for Gadolinium Isotopes with the DANCE Array

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

Dashdorj, D.; Mitchell, G. E.; Baramsai, B.

2009-03-10

The gadolinium isotopes are interesting for reactor applications as well as for medicine and astrophysics. The gadolinium isotopes have some of the largest neutron capture cross sections. As a consequence they are used in the control rod in reactor fuel assembly. From the basic science point of view, there are seven stable isotopes of gadolinium with varying degrees of deformation. Therefore they provide a good testing ground for the study of deformation dependent structure such as the scissors mode. Decay gamma rays following neutron capture on Gd isotopes are detected by the DANCE array, which is located at flight pathmore » 14 at the Lujan Neutron Scattering Center at Los Alamos National Laboratory. The high segmentation and close packing of the detector array enable gamma-ray multiplicity measurements. The calorimetric properties of the DANCE array coupled with the neutron time-of-flight technique enables one to gate on a specific resonance of a specific isotope in the time-of-flight spectrum and obtain the summed energy spectrum for that isotope. The singles gamma-ray spectrum for each multiplicity can be separated by their DANCE cluster multiplicity. Various photon strength function models are used for comparison with experimentally measured DANCE data and provide insight for understanding the statistical decay properties of deformed nuclei.« less

Zealots tame oscillations in the spatial rock-paper-scissors game

NASA Astrophysics Data System (ADS)

Szolnoki, Attila; Perc, Matjaž

2016-06-01

The rock-paper-scissors game is a paradigmatic model for biodiversity, with applications ranging from microbial populations to human societies. Research has shown, however, that mobility jeopardizes biodiversity by promoting the formation of spiral waves, especially if there is no conservation law in place for the total number of competing players. First, we show that even if such a conservation law applies, mobility still jeopardizes biodiversity in the spatial rock-paper-scissors game if only a small fraction of links of the square lattice is randomly rewired. Secondly, we show that zealots are very effective in taming the amplitude of oscillations that emerge due to mobility and/or interaction randomness, and this regardless of whether the later is quenched or annealed. While even a tiny fraction of zealots brings significant benefits, at 5% occupancy zealots practically destroy all oscillations regardless of the intensity of mobility, and regardless of the type and strength of randomness in the interaction structure. Interestingly, by annealed randomness the impact of zealots is qualitatively the same as by mobility, which highlights that fast diffusion does not necessarily destroy the coexistence of species, and that zealotry thus helps to recover the stable mean-field solution. Our results strengthen the important role of zealots in models of cyclic dominance, and they reveal fascinating evolutionary outcomes in structured populations that are a unique consequence of such uncompromising behavior.

Vibration analysis of rotor blades with an attached concentrated mass

NASA Technical Reports Server (NTRS)

Murthy, V. R.; Barna, P. S.

1977-01-01

The effect of an attached concentrated mass on the dynamics of helicopter rotor blades is determined. The point transmission matrix method was used to define, through three completely automated computer programs, the natural vibrational characteristics (natural frequencies and mode shapes) of rotor blades. The problems of coupled flapwise bending, chordwise bending, and torsional vibration of a twisted nonuniform blade and its special subcase pure torsional vibration are discussed. The orthogonality relations that exist between the natural modes of rotor blades with an attached concentrated mass are derived. The effect of pitch, rotation, and point mass parameters on the collective, cyclic, scissor, and pure torsional modes of a seesaw rotor blade is determined.

Early correction of unilateral scissor bite using transforce appliance and modified twin block appliance

PubMed Central

Chandorikar, Harshal; Nagrik, Arun; Bhad, Wasundhara A; Chavan, Santosh J; Doshi, Umal H

2017-01-01

Early treatment of scissor bite has been advocated mainly to prevent function jaw shift that can eventually lead to permanent skeletal asymmetry and temporomandibular joint pathosis. Although unilateral scissor bite is more common, most of the times, bilateral mandibular expansion is indicated. Lingual transforce appliance can be useful in such cases. This article presents a patient with unilateral scissor bite in mixed dentition with alveolar narrowing. Transforce appliance was used for scissor bite correction followed by modified twin block appliance for stabilization and settling of occlusion till the eruption of premolars. The case was finished with fixed mechanotherapy. Two years after completion of treatment, results were well maintained. Our results suggest that lingual transforce appliance along with careful management of occlusion is effective in the early management of severe unilateral scissor bite. PMID:28546961

The universal scissor component: Optimization of a reconfigurable component for deployable scissor structures

NASA Astrophysics Data System (ADS)

Alegria Mira, Lara; Thrall, Ashley P.; De Temmerman, Niels

2016-02-01

Deployable scissor structures are well equipped for temporary and mobile applications since they are able to change their form and functionality. They are structural mechanisms that transform from a compact state to an expanded, fully deployed configuration. A barrier to the current design and reuse of scissor structures, however, is that they are traditionally designed for a single purpose. Alternatively, a universal scissor component (USC)-a generalized element which can achieve all traditional scissor types-introduces an opportunity for reuse in which the same component can be utilized for different configurations and spans. In this article, the USC is optimized for structural performance. First, an optimized length for the USC is determined based on a trade-off between component weight and structural performance (measured by deflections). Then, topology optimization, using the simulated annealing algorithm, is implemented to determine a minimum weight layout of beams within a single USC component.

Carpal tunnel syndrome in women working in tea agriculture

PubMed Central

Devrimsel, Gul; Kirbas, Serkan; Yildirim, Murat; Turkyilmaz, Aysegul Kucukali; Sahin, Nilay

2014-01-01

OBJECTIVE: The aim of this cross-sectional study was to determine the frequency of carpal tunnel syndrome (CTS) among women using tea leaf scissors and compare it with normal population. METHODS: Two hundred hands of 100 women using tea leaf scissors (tea leaf scissors group) and 112 hands of 56 healthy women (control group) were clinically and electrophysiologically evaluated for CTS. Women using tea leaf scissors were evaluated with visual analog scale (VAS) for pain and Boston Carpal Tunnel Syndrome Questionnaire for symptoms and functional status. RESULTS: Carpal tunnel syndrome was diagnosed bilaterally in 62 (62%) and unilaterally in 7 (7%) women using tea leaf scissors, whereas 2 (3.57%) bilateral and 6 (10.71%) unilateral cases of CTS was diagnosed in controls. The differences in demographic factors were not statistically significant. In women with CTS using tea leaf scissors, mean symptom severity, functional status, and VAS scores were 2.73±0.60, 2.42±0.71 and 5.19±1.84, respectively. There was statistically significant difference in the frequency of CTS between women using tea leaf scissors and the control group and the risk of having CTS among women using tea leaf scissors was approximately 12 times greater (p<0.001). CONCLUSION: In tea agriculture, working with repetitive flexions and extensions of the wrist highly increases the risk of developing CTS. PMID:28058318

Digital computer program DF1758 fully coupled natural frequencies and mode shapes of a helicopter rotor blade

NASA Technical Reports Server (NTRS)

Bennett, R. L.

1975-01-01

The analytical techniques and computer program developed in the fully-coupled rotor vibration study are described. The rotor blade natural frequency and mode shape analysis was implemented in a digital computer program designated DF1758. The program computes collective, cyclic, and scissor modes for a single blade within a specified range of frequency for specified values of rotor RPM and collective angle. The analysis includes effects of blade twist, cg offset from reference axis, and shear center offset from reference axis. Coupled inplane, out-of-plane, and torsional vibrations are considered. Normalized displacements, shear forces and moments may be printed out and Calcomp plots of natural frequencies as a function of rotor RPM may be produced.

Scissors: More than a Cut Above

ERIC Educational Resources Information Center

Suzanne, Teri

2005-01-01

Scissors are a unique interactive tool when successfully used, allowing teachers and students to recognize and explore each other's creative ability while nurturing mutual communication. Freehand cutting gives children freedom to create as they cut. Scissors have the power to improve fine motor skills, stimulate creative imagination, reinforce…

Simple and Efficient Technique for Correction of Unilateral Scissor Bite Using Straight Wire.

PubMed

Dolas, Siddhesh Gajanan; Chitko, Shrikant Shrinivas; Kerudi, Veerendra Virupaxappa; Patil, Harshal Ashok; Bonde, Prasad Vasudeo

2016-03-01

Unilateral scissor bite is a relatively rare malocclusion. However, its correction is often difficult and a challenge for the clinician. This article presents simple and efficient technique for the correction of severe unilateral scissor bite in a 14 year old boy, using 0.020 S.S. A. J. Wilcock wire (premium plus) out of the spool, with minimal adjustments and placed in mandibular arch. After about six weeks time, good amount of correction was seen in the lower arch and the lower molar had been relieved of scissor bite.

Modeling the forces of cutting with scissors.

PubMed

Mahvash, Mohsen; Voo, Liming M; Kim, Diana; Jeung, Kristin; Wainer, Joshua; Okamura, Allison M

2008-03-01

Modeling forces applied to scissors during cutting of biological materials is useful for surgical simulation. Previous approaches to haptic display of scissor cutting are based on recording and replaying measured data. This paper presents an analytical model based on the concepts of contact mechanics and fracture mechanics to calculate forces applied to scissors during cutting of a slab of material. The model considers the process of cutting as a sequence of deformation and fracture phases. During deformation phases, forces applied to the scissors are calculated from a torque-angle response model synthesized from measurement data multiplied by a ratio that depends on the position of the cutting crack edge and the curve of the blades. Using the principle of conservation of energy, the forces of fracture are related to the fracture toughness of the material and the geometry of the blades of the scissors. The forces applied to scissors generally include high-frequency fluctuations. We show that the analytical model accurately predicts the average applied force. The cutting model is computationally efficient, so it can be used for real-time computations such as haptic rendering. Experimental results from cutting samples of paper, plastic, cloth, and chicken skin confirm the model, and the model is rendered in a haptic virtual environment.

Hand cumulative trauma disorders in Nigerian custom tailors: the need for redesign of manual scissors.

PubMed

Adeleye, Adedoyin Abiodun; Akanbi, Olusegun Gabriel

2015-01-01

Cutting scissors are important working tools for Nigerian custom tailors (CTs) but its usage apparently does not meet the ergonomics need of these artisans. A survey was carried out amongst CTs using questionnaires to obtain their background social-occupational demographics and observation methods to study their work performance, use of scissors and any cumulative trauma disorder (CTD) in their hands. Thicknesses of various fabrics were measured and comparison between Western world's custom tailoring job and the Nigerian type was done. The results showed some CTD risk factors with finger contusions on the 71 CTs evaluated. The right-hand contusions were traced to the constant usage of unpadded manual scissors with ungloved hands. Disparity between Western and Nigerian tailoring practice may account for the high occurrence of disorders in Nigerian CTs. Since hand dimensions are crucial in the design of hand tools, it is therefore concluded that hand anthropometry of Nigerian CTs and soft padding of manual scissors may mitigate CTD burdens on CTs' hands. Cumulative trauma disorders on the hands of low-income Nigerian CTs needed investigation. This was done via self-assessment and observational methods of the artisans’ work system. Frequent usage of unpadded manual scissors with un-gloved hands cause and exacerbate the problem. Hand anthropometry of users is crucial in scissors manufacturing.

Are we all doing it wrong? Influence of stripping and cleaving methods of laser fibers on laser lithotripsy performance.

PubMed

Kronenberg, Peter; Traxer, Olivier

2015-03-01

We assessed whether stripping and cleaving the laser fiber tip with specialized tools, namely laser fiber strippers, or ceramic or metal scissors, would influence lithotripsy performance. Laser fiber tips were stripped with a specialized laser fiber stripper or remained coated. The tips were then cleaved with metal or ceramic scissors. Laser lithotripsy experiments were performed with the 4 fiber tip combinations using an automated laser fragmentation testing system with artificial stones made of plaster of Paris or BegoStone Plus (Bego, Lincoln, Rhode Island). High frequency-low pulse energy (20 Hz and 0.5 J) and low frequency-high pulse energy (5 Hz and 2.0 J) settings were used for 30 seconds. Fissure width, depth and volume, and laser fiber tip photos were analyzed. Coated laser fiber tips always achieved significantly higher ablation volumes (sometimes greater than 50%) than stripped laser fiber tips (p <0.00001) regardless of cleaving scissor type, stone material or lithotripter setting. Coated fiber tips cleaved with metal scissors ablated as well as those cleaved with ceramic scissors (p = 0.16). However, stripped fibers were much less ablative when they were cut with metal scissors compared to ceramic scissors (p <0.00001). Harder stone material decreased ablation volume (p <0.00001). Low frequency-high pulse energy settings were an average of 3 times more ablative than high frequency-low pulse energy settings (p <0.00001). Stripping the fibers, a harder stone material and low frequency-high pulse energy settings were associated with increased fiber tip degradation. Coated laser fibers provided better lithotripsy performance and metal scissors were as good as ceramic scissors to cleave coated fibers. This knowledge may improve and simplify the way that laser lithotripsy procedures are done worldwide. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Simple and Efficient Technique for Correction of Unilateral Scissor Bite Using Straight Wire

PubMed Central

Dolas, Siddhesh Gajanan; Chitko, Shrikant Shrinivas; Kerudi, Veerendra Virupaxappa; Bonde, Prasad Vasudeo

2016-01-01

Unilateral scissor bite is a relatively rare malocclusion. However, its correction is often difficult and a challenge for the clinician. This article presents simple and efficient technique for the correction of severe unilateral scissor bite in a 14 year old boy, using 0.020 S.S. A. J. Wilcock wire (premium plus) out of the spool, with minimal adjustments and placed in mandibular arch. After about six weeks time, good amount of correction was seen in the lower arch and the lower molar had been relieved of scissor bite. PMID:27231682

Enhancement of Optical Nonlinearities in Composite Media and Structures via Local Fields and Electromagnetic Coupling Effects

NASA Technical Reports Server (NTRS)

Smith, David D.

2002-01-01

This talk will review the linear and nonlinear optical properties of metal nanoparticles and dielectric microparticles, with an emphasis on local field effects, and whispering gallery modes (WGMs), as well as the conjunction of these two effects for enhanced Raman. In particular, enhanced optical properties that result from electromagnetic coupling effects will be discussed in the context of Mie scattering from concentric spheres and bispheres. Predictions of mode splitting and photonic bandgaps in micro-spheres will be presented and will be shown to be analogous to effects that occur in coupled resonator optical waveguides (CROW). Slow and fast light in SCISSOR / CROW configurations will also be discussed.

Review of Livermore-Led Neutron Capture Studies Using DANCE

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

Parker, W; Sheets, S; Agvaanluvsan, U

2007-05-11

We have made neutron capture cross-section measurements using the white neutron source at the Los Alamos Science Center, the DANCE detector array (Detector for Advanced Neutron Capture Experiments) and targets important for basic science and stockpile stewardship. In this paper, we review results from (n,{gamma}) reactions on {sup 94,95}Mo, {sup 152,154,157,160,nat}Gd, {sup 151,153}Eu and {sup 242m}Am for neutron energies from < 1eV up to {approx} 20 keV. We measured details of the {gamma}-ray cascade following neutron capture, for comparison with results of statistical model simulations. We determined the neutron energy dependent (n,{gamma}) cross section and gained information about statistical decaymore » properties, including the nuclear level density and the photon strength function. Because of the high granularity of the detector array, it is possible to look at gamma cascades with a specified number of transitions (a specific multiplicity). We simulated {gamma}-ray cascades using a combination of the DICEBOX/GEANT computer codes. In the case of the deformed nuclei, we found evidence of a scissors-mode resonance. For the Eu, we also determined the (n,{gamma}) cross sections. For the {sup 94,95}Mo, we focused on the spin and parity assignments of the resonances and the determination of the photon strength functions for the compound nuclei {sup 95,96}Mo. Future plans include measurements on actinide targets; our immediate interest is in {sup 242m}Am.« less

Chemical scissors cut phosphorene and their novel electronic properties

NASA Astrophysics Data System (ADS)

Peng, Xihong; Wei, Qun

2015-03-01

Phosphorene, a recently fabricated two-dimensional puckered honeycomb structure of black phosphorus, showed promising properties for applications in nano-electronics. In this work, we report a chemical scissors effect on phosphorene, using first principles density-functional methods. It was found that chemical species, such as H, OH, F, and Cl, can act as scissors to cut phosphorene. Phosphorus nanochains and nanoribbons can be obtained using such chemical scissors. The scissors effect results from the strong bonding between the chemical species and phosphorus atoms. Other species such as O, S and Se fail to cut phosphorene due to their weak bonding with phosphorus. The electronic structures of the produced P-chains reveal that the hydrogenated P-chain is an insulator; however, the pristine P-chain is a one-dimensional Dirac material, in which the charge carriers are massless fermions travelling at an effective speed of light approximately 8x105 m/s. The obtained zigzag phosphorene nanoribbons show either metallic or semiconducting behaviors, depending on the treatment of the edge phosphorus atoms.

Learning the rules of the rock-paper-scissors game: chimpanzees versus children.

PubMed

Gao, Jie; Su, Yanjie; Tomonaga, Masaki; Matsuzawa, Tetsuro

2018-01-01

The present study aimed to investigate whether chimpanzees (Pan troglodytes) could learn a transverse pattern by being trained in the rules of the rock-paper-scissors game in which "paper" beats "rock," "rock" beats "scissors," and "scissors" beats "paper." Additionally, this study compared the learning processes between chimpanzees and children. Seven chimpanzees were tested using a computer-controlled task. They were trained to choose the stronger of two options according to the game rules. The chimpanzees first engaged in the paper-rock sessions until they reached the learning criterion. Subsequently, they engaged in the rock-scissors and scissors-paper sessions, before progressing to sessions with all three pairs mixed. Five of the seven chimpanzees completed training after a mean of 307 sessions, which indicates that they learned the circular pattern. The chimpanzees required more scissors-paper sessions (14.29 ± 6.89), the third learnt pair, than paper-rock (1.71 ± 0.18) and rock-scissors (3.14 ± 0.70) sessions, suggesting they had difficulty finalizing the circularity. The chimpanzees then received generalization tests using new stimuli, which they learned quickly. A similar procedure was performed with children (35-71 months, n = 38) who needed the same number of trials for all three pairs during single-paired sessions. Their accuracy during the mixed-pair sessions improved with age and was better than chance from 50 months of age, which indicates that the ability to solve the transverse patterning problem might develop at around 4 years of age. The present findings show that chimpanzees were able to learn the task but had difficulties with circularity, whereas children learned the task more easily and developed the relevant ability at approximately 4 years of age. Furthermore, the chimpanzees' performance during the mixed-pair sessions was similar to that of 4-year-old children during the corresponding stage of training.

[Ultrasonic scissors. New vs resterilized instruments].

PubMed

Gärtner, D; Münz, K; Hückelheim, E; Hesse, U

2008-02-01

The aim of this study was to compare reliability in handling and function of resterilized and single-use disposable ultrasonic scissors. In a prospective randomized study, the surgeon blindly tested new and resterilized ultrasonographic scissors. The parameters were force of activation, cutting effect, coagulation effect, error messages, and disturbing generator noise. Fifty-one new and 49 resterilized instruments in 94 operations were evaluated. The differences in force of activation, cutting effect, and coagulation were not significant. Error messages and disturbing noises were rare in both groups. Six new instruments and two resterilized instruments had to be exchanged because of problems during surgery. This study demonstrates comparable reliability in function and handling of resterilized and new ultrasonic scissors. The use of resterilized instruments leads to distinctly reduced costs and could contribute to efficiency in laparoscopic surgery.

Manipulation of mammalian cells using a single-fiber optical microbeam

PubMed Central

Mohanty, Samarendra K.; Mohanty, Khyati S.; Berns, Michael W.

2014-01-01

The short working distance of microscope objectives has severely restricted the application of optical micromanipulation techniques at larger depths. We show the first use of fiber-optic tweezers toward controlled guidance of neuronal growth cones and stretching of neurons. Further, by mode locking, the fiber-optic tweezers beam was converted to fiber-optic scissors, enabling dissection of neuronal processes and thus allowing study of the subsequent response of neurons to localized injury. At high average powers, lysis of a three-dimensionally trapped cell was accomplished. PMID:19021429

Scissors stab wound to the cervical spinal cord at the craniocervical junction.

PubMed

Zhang, Xiao-Yong; Yang, Ying-Ming

2016-06-01

Stab wounds resulting in spinal cord injury of the craniocervical junction are rare. A scissors stab wound to the cervical spinal cord has been reported only once in the literature. This paper aimed to report a case of Brown-Séquard-plus syndrome in an 8-year-old boy secondary to a scissors stab wound at the craniocervical junction. Case report and review of the literature. Case report of an 8-year-old boy accidentally stabbed in the neck by scissors, which were thrown as a dart. The case study of an 8-year-old boy who was hospitalized because of a scissors stab wound at the craniocervical junction. The patient developed Brown-Séquard-plus syndrome on the left side of the body. Magnetic resonance imaging revealed a laceration of the spinal cord at the craniocervical junction with cerebrospinal fluid leakage. Careful cleansing and interrupted sutures of the wounds were performed to prevent cerebrospinal fluid leakage. Rehabilitation therapy was performed 2 days later. A follow-up examination revealed complete recovery of the neurologic deficit 8 months post-injury. Treatment of scissors stab wounds to the cervical spinal cord, whether conservative management or thorough surgical exploration, should be individualized based on history, examination, and imaging. As shown in this case report, despite conservative management, complete recovery, which was unexpected, was attributed to the initial mild laceration of the spinal cord and ipsilateral spinal cord functional compensation. Copyright © 2016 Elsevier Inc. All rights reserved.

Reexamining the role of the (n ,γ f ) process in the low-energy fission of 235U and 239Pu

NASA Astrophysics Data System (ADS)

Lynn, J. E.; Talou, P.; Bouland, O.

2018-06-01

The (n ,γ f ) process is reviewed in light of modern nuclear reaction calculations in both slow and fast neutron-induced fission reactions on 235U and 239Pu. Observed fluctuations of the average prompt fission neutron multiplicity and average total γ -ray energy below 100-eV incident neutron energy are interpreted in this framework. The surprisingly large contribution of the M 1 transitions to the prefission γ -ray spectrum of 239Pu is explained by the dominant fission probabilities of 0+ and 2+ transition states, which can only be accessed from compound nucleus states formed by the interaction of s -wave neutrons with the target nucleus in its ground state, and decaying through M 1 transitions. The impact of an additional low-lying M 1 scissors mode in the photon strength function is analyzed. We review experimental evidence for fission fragment mass and kinetic-energy fluctuations in the resonance region and their importance in the interpretation of experimental data on prompt neutron data in this region. Finally, calculations are extended to the fast energy range where (n ,γ f ) corrections can account for up to 3% of the total fission cross section and about 20% of the capture cross section.

Surgical scissors extension adds the 7th axis of force feedback to the Freedom 6S.

PubMed

Powers, Marilyn J; Sinclair, Ian P W; Brouwer, Iman; Laroche, Denis

2007-01-01

A virtual reality surgical simulator ideally allows seamless transition between the real and virtual world. In that respect, all of a surgeon's motions and tools must be simulated. Until now researchers have been limited to using a pen-like tool in six degrees-of-freedom. This paper presents the addition of haptically enabled scissors to the end effector of a 6-DOF haptic device, the Freedom 6S. The scissors are capable of pinching a maximum torque of 460 mN.m with low inertia and low back-drive friction. The device is a balanced design so that the user feels like they are holding no more than actual scissors, although with some added inertia on the load end. The system is interchangeable between the 6-DOF and 7-DOF configurations to allow switching tools quickly.

Comparison between scissor and laser resections of intrauterine septa in hysteroscopy

NASA Astrophysics Data System (ADS)

Wilczak, Maciej; Wozniak, Jakub; Cwojdzinski, Marek; Sajdak, Stefan; Opala, Tomasz; Pisarski, Tadeusz

1996-03-01

The comparison between results of scissors- and Nd-YAG laser-resection of intrauterine septa in hysteroscopy was shown. In 12 patients the scissors-resection and in 11 women the laser- resection was done. In the group of patients after laser procedure 10 of them were pregnant and 9 delivered healthy children. One missed abortion was diagnosed in the twenty-first week of gestation. After scissors-resection 7 women became pregnant and 5 of them bore mature children. Two of those seven lost their gestation (spontaneous abortions in the nineteenth and twentieth weeks of pregnancy). In the authors' opinion hysteroscopy is a very useful method of diagnostics and therapy of intrauterine septa. The Nd-YAG laser-resection of intrauterine septa seems to be the method with the lowest number of complications. Fertility and parity highly improves after removal of the septa localized in the uterine cavity.

Flexible RF filter using a nonuniform SCISSOR.

PubMed

Zhuang, Leimeng

2016-03-15

This work presents a flexible radiofrequency (RF) filter using an integrated microwave photonic circuit that comprises a nonuniform side-coupled integrated spaced sequence of resonators (N-SCISSOR). The filter passband can be reconfigured by varying the N-SCISSOR parameters. When employing a dual-parallel Mach-Zechnder modulator, the filter is also able to perform frequency down-conversion. In the experiment, various filter response shapes are shown, ranging from a flat-top band-pass filter to a total opposite high-rejection (>40  dB) notch filter, with a frequency coverage of greater than two octaves. The frequency down-conversion function is also demonstrated.

Stereoscopic Analysis of Silicone Breast Implant Shells Damaged by Surgical Instruments.

PubMed

Rapp, Derek A; Neaman, Keith C; Hammond, Dennis C

2015-07-01

Iatrogenic shell injury during the implantation and explantation of silicone gel breast implants may lead to eventual device failure. Identification of the patterns of injury caused by surgical instruments is important when attempting to characterize the cause of shell rupture. Understanding the true causes of device failure may help with its prevention. The purpose of this study was to microscopically characterize patterns of shell injury induced by various surgical instruments. Textured and smooth silicone gel implants were intentionally damaged with a variety of surgical instruments. Various scalpels and surgical scissors ranging in fineness were used to create full-thickness injuries in the implant shell. Optical microscopy and scanning electron microscopy were then used to image the injured area to determine patterns of injury. Full-thickness striations across the thickness of the shell could be seen with damage caused by scissors. The density of these striations correlated directly with the fineness of scissors used. No striations were seen with injuries caused by scalpels. Striations were only observed in injuries caused by scissors and suture needles. Striation density correlated with the coarseness of the cutting edge. No such striations were seen in shells damaged by a scalpel even when the angle of approach was changed. This difference can be of assistance in distinguishing between scissors versus scalpel injury of an implant shell.

The Amount and Preferred Orientation of Simple-shear in a Deformation Tensor: Implications for Detecting Shear Zones and Faults with GPS

NASA Astrophysics Data System (ADS)

Johnson, A. M.; Griffiths, J. H.

2007-05-01

At the 2005 Fall Meeting of the American Geophysical Union, Griffiths and Johnson [2005] introduced a method of extracting from the deformation-gradient (and velocity-gradient) tensor the amount and preferred orientation of simple-shear associated with 2-D shear zones and faults. Noting the 2-D is important because the shear zones and faults in Griffiths and Johnson [2005] were assumed non-dilatant and infinitely long, ignoring the scissors- like action along strike associated with shear zones and faults of finite length. Because shear zones and faults can dilate (and contract) normal to their walls and can have a scissors-like action associated with twisting about an axis normal to their walls, the more general method of detecting simple-shear is introduced and called MODES "method of detecting simple-shear." MODES can thus extract from the deformation-gradient (and velocity- gradient) tensor the amount and preferred orientation of simple-shear associated with 3-D shear zones and faults near or far from the Earth's surface, providing improvements and extensions to existing analytical methods used in active tectonics studies, especially strain analysis and dislocation theory. The derivation of MODES is based on one definition and two assumptions: by definition, simple-shear deformation becomes localized in some way; by assumption, the twirl within the deformation-gradient (or the spin within the velocity-gradient) is due to a combination of simple-shear and twist, and coupled with the simple- shear and twist is a dilatation of the walls of shear zones and faults. The preferred orientation is thus the orientation of the plane containing the simple-shear and satisfying the mechanical and kinematical boundary conditions. Results from a MODES analysis are illustrated by means of a three-dimensional diagram, the cricket- ball, which is reminiscent of the seismologist's "beach ball." In this poster, we present the underlying theory of MODES and illustrate how it works by analyzing the three- dimensional displacements measured with the Global Positioning System across the 1999 Chi-Chi earthquake ground rupture in Taiwan. In contrast to the deformation zone in the upper several meters of the ground below the surface detected by Yu et al. [2001], MODES determines the orientation and direction of shift of a shear zone representing the earthquake fault within the upper several hundred or thousand meters of ground below the surface. Thus, one value of the MODES analysis in this case is to provide boundary conditions for dislocation solutions for the subsurface shape of the main rupture during the earthquake.

Calculus, Paper, Scissors

ERIC Educational Resources Information Center

Flores, Luis; Flores, Alfinio

2006-01-01

The idea of cutting out a curve while looking at the direction of cut of the scissors is used to explore concepts related to curves, tangents and derivatives, especially tangent line, concavity and points of inflection, curvature, and a curve as envelope of tangent lines. (Contains 6 figures.)

Chemical scissors cut phosphorene nanostructures

NASA Astrophysics Data System (ADS)

Peng, Xihong; Wei, Qun

2014-12-01

Phosphorene, a recently fabricated two-dimensional puckered honeycomb structure of phosphorus, showed promising properties for applications in nano-electronics. In this work, we report a chemical scissors effect on phosphorene, using first-principles method. It was found that chemical species, such as H, OH, F, and Cl, can act as scissors to cut phosphorene. Phosphorus nanochains and nanoribbons can be obtained. The scissors effect results from the strong bonding between the chemical species and phosphorus atoms. Other species such as O, S and Se fail to cut phosphorene nanostructures due to their weak bonding with phosphorus. The electronic structures of the produced P-chains reveal that the hydrogenated chain is an insulator while the pristine chain is a one-dimensional Dirac material, in which the charge carriers are massless fermions travelling at an effective speed of light ˜8 × 105 m s-1. The obtained zigzag phosphorene nanoribbons show either metallic or semiconducting behaviors, depending on the treatment of the edge phosphorus atoms.

Characterization of adsorbed water in MIL-53(Al) by FTIR spectroscopy and ab-initio calculations.

PubMed

Salazar, J M; Weber, G; Simon, J M; Bezverkhyy, I; Bellat, J P

2015-03-28

Here, we report ab-initio calculations developed with a twofold purpose: understand how adsorbed water molecules alter the infrared spectrum of the metal-organic framework MIL-53(Al) and to investigate which are the associated physico-chemical processes. The analyzed structures are the two anhydrous narrow (np⊘) and large (lp⊘) pore forms and the hydrated narrow pore form (np-H2O) of the MIL-53(Al). For these structures, we determined their corresponding infrared spectra (FTIR) and we identified the vibrational modes associated to the dominant spectral lines. We show that wagging and scissoring modes of CO2 give flexibility to the structure for facilitating the lp⊘- np⊘ transition. In our studies, this transition is identified by eight vibrational modes including the δCH(18a) vibrational mode currently used to identify the mentioned transition. We report an exhaustive band identification of the infrared spectra associated to the analyzed structures. Moreover, the FTIR for the np-H2O structure allowed us to identify four types of water molecules linked to the host structure by one to three hydrogen bonds.

Scale-free memory model for multiagent reinforcement learning. Mean field approximation and rock-paper-scissors dynamics

NASA Astrophysics Data System (ADS)

Lubashevsky, I.; Kanemoto, S.

2010-07-01

A continuous time model for multiagent systems governed by reinforcement learning with scale-free memory is developed. The agents are assumed to act independently of one another in optimizing their choice of possible actions via trial-and-error search. To gain awareness about the action value the agents accumulate in their memory the rewards obtained from taking a specific action at each moment of time. The contribution of the rewards in the past to the agent current perception of action value is described by an integral operator with a power-law kernel. Finally a fractional differential equation governing the system dynamics is obtained. The agents are considered to interact with one another implicitly via the reward of one agent depending on the choice of the other agents. The pairwise interaction model is adopted to describe this effect. As a specific example of systems with non-transitive interactions, a two agent and three agent systems of the rock-paper-scissors type are analyzed in detail, including the stability analysis and numerical simulation. Scale-free memory is demonstrated to cause complex dynamics of the systems at hand. In particular, it is shown that there can be simultaneously two modes of the system instability undergoing subcritical and supercritical bifurcation, with the latter one exhibiting anomalous oscillations with the amplitude and period growing with time. Besides, the instability onset via this supercritical mode may be regarded as “altruism self-organization”. For the three agent system the instability dynamics is found to be rather irregular and can be composed of alternate fragments of oscillations different in their properties.

Main interior space facing south toward the ocean. Original scissor ...

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

Main interior space facing south toward the ocean. Original scissor trusses and deck roof are visible at the top. Octagonal window with large picture windows face the ocean. - San Luis Yacht Club, Avila Pier, South of Front Street, Avila Beach, San Luis Obispo County, CA

Statistical properties of Pu 243 , and Pu 242 ( n , γ ) cross section calculation

DOE PAGES

Laplace, T. A.; Zeiser, F.; Guttormsen, M.; ...

2016-01-29

The level density and γ-ray strength function (γSF) of 243Pu have been measured in the quasicontinuum using the Oslo method. Excited states in 243Pu were populated using the 242Pu(d,p) reaction. The level density closely follows the constant-temperature level density formula for excitation energies above the pairing gap. The γSF displays a double-humped resonance at low energy as also seen in previous investigations of actinide isotopes. The structure is interpreted as the scissors resonance and has a centroid of ω SR = 2.42(5) MeV and a total strength of B SR = 10.1(15) μ 2 N, which is in excellent agreementmore » with sum-rule estimates. Lastly, the measured level density and γSF were used to calculate the 242Pu(n,γ) cross section in a neutron energy range for which there were previously no measured data.« less

Mola Scissors: An Exercise in Design.

ERIC Educational Resources Information Center

Carson, Janet

1982-01-01

Describes a design exercise for college education majors. Five paper scissor shapes are used to illustrate the role of balance, variation, repetition, and unity in design. After comparing their own designs to Indian molas, students explore how color and shape affect design by elaborating their work with oil crayons. (AM)

Scissor Sorcery: Cutting Activities for the Early Childhood Curriculum.

ERIC Educational Resources Information Center

Carpenter, Sharan Bryant

This handbook, designed for use with preschool and elementary age children, provides instructions and instructional materials for the development of proficiency in cutting. Scissor cutting is a critically important activity for young children to practice because, along with coloring and pasting, it is used widely to foster the three R's as well as…

Local dispersal promotes biodiversity in a real-life game of rock-paper-scissors

NASA Astrophysics Data System (ADS)

Kerr, Benjamin; Riley, Margaret A.; Feldman, Marcus W.; Bohannan, Brendan J. M.

2002-07-01

One of the central aims of ecology is to identify mechanisms that maintain biodiversity. Numerous theoretical models have shown that competing species can coexist if ecological processes such as dispersal, movement, and interaction occur over small spatial scales. In particular, this may be the case for non-transitive communities, that is, those without strict competitive hierarchies. The classic non-transitive system involves a community of three competing species satisfying a relationship similar to the children's game rock-paper-scissors, where rock crushes scissors, scissors cuts paper, and paper covers rock. Such relationships have been demonstrated in several natural systems. Some models predict that local interaction and dispersal are sufficient to ensure coexistence of all three species in such a community, whereas diversity is lost when ecological processes occur over larger scales. Here, we test these predictions empirically using a non-transitive model community containing three populations of Escherichia coli. We find that diversity is rapidly lost in our experimental community when dispersal and interaction occur over relatively large spatial scales, whereas all populations coexist when ecological processes are localized.

Reexamining the role of the ( n , γ f ) process in the low-energy fission of U 235 and Pu 239

DOE PAGES

Lynn, J. E.; Talou, P.; Bouland, O.

2018-06-01

In this paper, themore » $$(n,{\\gamma}f)$$ process is reviewed in light of modern nuclear reaction calculations in both slow and fast neutron-induced fission reactions on $$^{235}\\mathrm{U}$$ and $$^{239}\\mathrm{Pu}$$. Observed fluctuations of the average prompt fission neutron multiplicity and average total $${\\gamma}$$-ray energy below 100-eV incident neutron energy are interpreted in this framework. The surprisingly large contribution of the $M1$ transitions to the prefission $${\\gamma}$$-ray spectrum of $$^{239}\\mathrm{Pu}$$ is explained by the dominant fission probabilities of $${0}^{+}$$ and $${2}^{+}$$ transition states, which can only be accessed from compound nucleus states formed by the interaction of $s$-wave neutrons with the target nucleus in its ground state, and decaying through $M1$ transitions. The impact of an additional low-lying $M1$ scissors mode in the photon strength function is analyzed. We review experimental evidence for fission fragment mass and kinetic-energy fluctuations in the resonance region and their importance in the interpretation of experimental data on prompt neutron data in this region. In conclusion, calculations are extended to the fast energy range where $$(n,{\\gamma}f)$$ corrections can account for up to 3% of the total fission cross section and about 20% of the capture cross section.« less

Reexamining the role of the ( n , γ f ) process in the low-energy fission of U 235 and Pu 239

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

Lynn, J. E.; Talou, P.; Bouland, O.

In this paper, themore » $$(n,{\\gamma}f)$$ process is reviewed in light of modern nuclear reaction calculations in both slow and fast neutron-induced fission reactions on $$^{235}\\mathrm{U}$$ and $$^{239}\\mathrm{Pu}$$. Observed fluctuations of the average prompt fission neutron multiplicity and average total $${\\gamma}$$-ray energy below 100-eV incident neutron energy are interpreted in this framework. The surprisingly large contribution of the $M1$ transitions to the prefission $${\\gamma}$$-ray spectrum of $$^{239}\\mathrm{Pu}$$ is explained by the dominant fission probabilities of $${0}^{+}$$ and $${2}^{+}$$ transition states, which can only be accessed from compound nucleus states formed by the interaction of $s$-wave neutrons with the target nucleus in its ground state, and decaying through $M1$ transitions. The impact of an additional low-lying $M1$ scissors mode in the photon strength function is analyzed. We review experimental evidence for fission fragment mass and kinetic-energy fluctuations in the resonance region and their importance in the interpretation of experimental data on prompt neutron data in this region. In conclusion, calculations are extended to the fast energy range where $$(n,{\\gamma}f)$$ corrections can account for up to 3% of the total fission cross section and about 20% of the capture cross section.« less

Evaluation of the split cantilever beam for Mode 3 delamination testing

NASA Technical Reports Server (NTRS)

Martin, Roderick H.

1989-01-01

A test rig for testing a thick split cantilever beam for scissoring delamination (mode 3) fracture toughness was developed. A 3-D finite element analysis was conducted on the test specimen to determine the strain energy release rate, G, distribution along the delamination front. The virtual crack closure technique was used to calculate the G components resulting from interlaminar tension, GI, interlaminar sliding shear, GII, and interlaminar tearing shear, GIII. The finite element analysis showed that at the delamination front no GI component existed, but a GII component was present in addition to a GIII component. Furthermore, near the free edges, the GII component was significantly higher than the GIII component. The GII/GIII ratio was found to increase with delamination length but was insensitive to the beam depth. The presence of GII at the delamination front was verified experimentally by examination of the failure surfaces. At the center of the beam, where the failure was in mode 3, there was significant fiber bridging. However, at the edges of the beam where the failure was in mode 3, there was no fiber bridging and mode 2 shear hackles were observed. Therefore, it was concluded that the split cantilever beam configuration does not represent a pure mode 3 test. The experimental work showed that the mode 2 fracture toughness, GIIc, must be less than the mode 3 fracture toughness, GIIIc. Therefore, a conservative approach to characterizing mode 3 delamination is to equate GIIIc to GIIc.

Nonlinear Kerr enhancement of the Sagnac effect in a coherently coupled array of optical microresonators

NASA Astrophysics Data System (ADS)

Wang, Chao; Search, Christopher

2013-03-01

Optical gyroscopes based on the Sagnac effect are of great interest both theoretically and practically. Previously it has been suggested a nonlinear Kerr medium inserted into a ring resonator gyroscope can largely increase the rotation sensitivity due to an instability caused by the non-reciprocal self-phase and cross-phase modulations. Recently, coupled microresonator arrays such as Side-Coupled Integrated Spaced Sequence of Resonators (SCISSOR) and Coupled Resonator Optical Waveguides (CROW) have drawn interest as potential integrated gyroscopes due to the sensitivity enhancement resulting from distributed interference between resonators. Here we analyze a SCISSOR system, which consists of an array of microresonators evanescently coupled to two parallel bus waveguides in the presence of a strong intra-resonator Kerr nonlinearity. We show that the distributed interference in the waveguides combined with the nonlinearly enhanced Sagnac effect in the resonators can further improve the sensitivity compared with either a single resonator of equal footprint or SCISSOR without a Kerr nonlinearity. Numerical simulation shows that bistability in the SCISSOR occurs and the rotation sensitivity dIoutput/dω can go to infinity near the boundaries of the bistable region.

Nose biopsy: a comparison between two sampling techniques.

PubMed

Segal, Nili; Osyntsov, Lidia; Olchowski, Judith; Kordeluk, Sofia; Plakht, Ygal

2016-06-01

Pre operative biopsy is important in obtaining preliminary information that may help in tailoring the optimal treatment. The aim of this study was to compare two sampling techniques of obtaining nasal biopsy-nasal forceps and nasal scissors in terms of pathological results. Biopsies of nasal lesions were taken from patients undergoing nasal surgery by two techniques- with nasal forceps and with nasal scissors. Each sample was examined by a senior pathologist that was blinded to the sampling method. A grading system was used to rate the crush artifact in every sample (none, mild, moderate, severe). A comparison was made between the severity of the crush artifact and the pathological results of the two techniques. One hundred and forty-four samples were taken from 46 patients. Thirty-one were males and the mean age was 49.6 years. Samples taken by forceps had significantly higher grades of crush artifacts compared to those taken by scissors. The degree of crush artifacts had a significant influence on the accuracy of the pre operative biopsy. Forceps cause significant amount of crush artifacts compared to scissors. The degree of crush artifact in the tissue sample influences the accuracy of the biopsy.

Measurement of the {sup 157}Gd(n,{gamma}) reaction with the DANCE {gamma} calorimeter array

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

Chyzh, A.; Dashdorj, D.; Lawrence Livermore National Laboratory, Livermore, California 94551

2011-07-15

The {sup 157}Gd(n,{gamma}) reaction was measured with the DANCE {gamma} calorimeter (consisting of 160 BaF{sub 2} scintillation detectors) at the Los Alamos Neutron Science Center. The multiplicity distributions of the {gamma} decay were used to determine the resonance spins up to E{sub n}=300 eV. The {gamma}-ray energy spectra for different multiplicities were measured for the s-wave resonances. The shapes of these spectra were compared with simulations based on the use of the DICEBOX statistical model code. Simulations showed that the scissors mode is required not only for the ground-state transitions but also for transitions between excited states.

Beyond Scissors and Glue: Staff Developers Guide Teachers in Piecing Together a Vertically Aligned Curriculum and in Creating a Method to Get This Job Done

ERIC Educational Resources Information Center

Phelps, Vickie

2005-01-01

Layers and layers of curricula stuffed into vinyl binders were the norm in this Texas district until teachers sat down with scissors and glue to create a vertically aligned curriculum. They then created standards-based lessons to support the curriculum and put them into a database readily accessible by all.

Scissor-type knife significantly improves self-completion rate of colorectal endoscopic submucosal dissection: Single-center prospective randomized trial.

PubMed

Yamashina, Takeshi; Takeuchi, Yoji; Nagai, Kengo; Matsuura, Noriko; Ito, Takashi; Fujii, Mototsugu; Hanaoka, Noboru; Higashino, Koji; Uedo, Noriya; Ishihara, Ryu; Iishi, Hiroyasu

2017-05-01

Colorectal endoscopic submucosal dissection (C-ESD) is recognized as a difficult procedure. Recently, scissors-type knives were launched to reduce the difficulty of C-ESD. The aim of this study was to evaluate the efficacy and safety of the combined use of a scissors-type knife and a needle-type knife with a water-jet function (WJ needle-knife) for C-ESD compared with using the WJ needle-knife alone. This was a prospective randomized controlled trial in a referral center. Eighty-five patients with superficial colorectal neoplasms were enrolled and randomly assigned to undergo C-ESD using a WJ needle-knife alone (Flush group) or a scissor-type knife-supported WJ needle-knife (SB Jr group). Procedures were conducted by two supervised residents. Primary endpoint was self-completion rate by the residents. Self-completion rate was 67% in the SB Jr group, which was significantly higher than that in the Flush group (39%, P = 0.01). Even after exclusion of four patients in the SB Jr group in whom C-ESD was completed using the WJ needle-knife alone, the self-completion rate was significantly higher (63% vs 39%; P = 0.03). Median procedure time among the self-completion cases did not differ significantly between the two groups (59 vs 51 min; P = 0.14). No fatal adverse events were observed in either group. In this single-center phase II trial, scissor-type knife significantly improved residents' self-completion rate for C-ESD, with no increase in procedure time or adverse events. A multicenter trial would be warranted to confirm the validity of the present study. © 2016 Japan Gastroenterological Endoscopy Society.

Spiraling patterns in evolutionary models inspired by bacterial games with cyclic dominance

NASA Astrophysics Data System (ADS)

Mobilia, Mauro

2015-03-01

Understanding the mechanisms allowing the maintenance of biodiversity is a central issue in biology. Evolutionary game theory, where the success of one species depends on what the others are doing, provides a promising framework to investigate this complex problem. Experiments on microbial populations have shown that cyclic local interactions promote species coexistence. In this context, rock-paper-scissors games - in which rock crushes scissors, scissors cut paper, and paper wraps rock - are often used to model the dynamics of populations in cyclic competition. After a brief survey of some inspiring experiments, I will discuss the subtle interplay between individuals' mobility and their local interactions in two-dimensional rock-paper-scissors systems. This leads to the loss of biodiversity above a certain mobility threshold, and to the formation of spiraling patterns below the critical mobility rate. I will then study a generic rock-paper-scissors metapopulation model formulated on a two-dimensional grid of patches. When these have a large carrying capacity, the model's dynamics is faithfully described in terms of the system's complex Ginzburg-Landau equation properly derived from a multiscale expansion. The properties of the ensuing complex Ginzburg-Landau equation are exploited to derive the system's phase diagram and to characterize the spatio-temporal properties of the spiraling patterns in each phase. This enables us to analyze the spiral waves stability, how these are influenced by linear and nonlinear diffusion, and to discuss phenomena such as far-field breakup. Presentation mainy based on joint work with B. Szczesny and A. M. Rucklidge. Fruitful earlier collaborations with E. Frey, Q. He, T. Reichenbach, and U. C. Täuber are also acknowledged. Work supported by the UK EPSRC (Grant No. EP/P505593/1).

Clonal selection prevents tragedy of the commons when neighbors compete in a rock-paper-scissors game

NASA Astrophysics Data System (ADS)

Juul, Jeppe; Sneppen, Kim; Mathiesen, Joachim

2012-06-01

The rock-paper-scissors game is a model example of the ongoing cyclic turnover typical of many ecosystems, ranging from the terrestrial and aquatic to the microbial. Here we explore the evolution of a rock-paper-scissors system where three species compete for space. The species are allowed to mutate and change the speed by which they invade one another. In the case when all species have similar mutation rates, we observe a perpetual arms race where no single species prevails. When only two species mutate, their aggressions increase indefinitely until the ecosystem collapses and only the nonmutating species survives. Finally we show that when only one species mutates, group selection removes individual predators with the fastest growth rates, causing the growth rate of the species to stabilize. We explain this group selection quantitatively.

Paper-cutting operations using scissors in Drury's law tasks.

PubMed

Yamanaka, Shota; Miyashita, Homei

2018-05-01

Human performance modeling is a core topic in ergonomics. In addition to deriving models, it is important to verify the kinds of tasks that can be modeled. Drury's law is promising for path tracking tasks such as navigating a path with pens or driving a car. We conducted an experiment based on the observation that paper-cutting tasks using scissors resemble such tasks. The results showed that cutting arc-like paths (1/4 of a circle) showed an excellent fit with Drury's law (R 2  > 0.98), whereas cutting linear paths showed a worse fit (R 2  > 0.87). Since linear paths yielded better fits when path amplitudes were divided (R 2  > 0.99 for all amplitudes), we discuss the characteristics of paper-cutting operations using scissors. Copyright © 2018 Elsevier Ltd. All rights reserved.

Scissor bite in a young patient treated with an orthodontic-orthopedic device. A case report.

PubMed

Favero, V; Sbricoli, L; Favero, L

2013-06-01

Scissor bite is a rare malocclusion that often leads to minor facial asymmetry. An orthodontic and orthopaedic correction is advisable in young patients to prevent subsequent temporomandibular diseases requesting maxillofacial intervention. In this case report a 8-year-old girl in mixed dentition with unilateral left scissor bite was treated with a modified Rapid Palatal Expander. To modify an overexpanded maxilla (width 39 mm measured between both upper first molars) the device was used to close rather than to expand, without need of patient compliance. Orthodontic correction was then completed with traditional bracketing. Results were tangible (width 36 mm) and remained stable even for at least 2 years after retention. This original device has proved to be useful in this kind of situations and can be easily applied to young patient to correct such malocclusions.

Spatially sculpted laser scissors for study of DNA damage and repair

NASA Astrophysics Data System (ADS)

Stephens, Jared; Mohanty, Samarendra K.; Genc, Suzanne; Kong, Xiangduo; Yokomori, Kyoko; Berns, Michael W.

2009-09-01

We present a simple and efficient method for controlled linear induction of DNA damage in live cells. By passing a pulsed laser beam through a cylindrical lens prior to expansion, an elongated elliptical beam profile is created with the ability to expose controlled linear patterns while keeping the beam and the sample stationary. The length and orientation of the beam at the sample plane were reliably controlled by an adjustable aperture and rotation of the cylindrical lens, respectively. Localized immunostaining by the DNA double strand break (DSB) markers phosphorylated H2AX (γH2AX) and Nbs1 in the nuclei of HeLa cells exposed to the ``line scissors'' was shown via confocal imaging. The line scissors method proved more efficient than the scanning mirror and scanning stage methods at induction of DNA DSB damage with the added benefit of having a greater potential for high throughput applications.

Challenge of false alarms in nitroaromatic explosive detection--a detection device based on surface-enhanced Raman spectroscopy.

PubMed

Wackerbarth, Hainer; Gundrum, Lars; Salb, Christian; Christou, Konstantin; Viöl, Wolfgang

2010-08-10

A challenge in the detection of explosives is the differentiation between explosives and contaminants. Synthetic musk-containing perfumes can cause false alarms, as these perfumes are nitroaromatic compounds, which can be mistaken for trinitro toluene (TNT) by some detectors. We present a detection principle based on surface-enhanced Raman scattering (SERS). A stream of the airborne compounds is focused and resublimated on a cooled nanostructured gold surface. We recorded high-resolution SERS spectra of TNT, musk xylene, and musk ketone. The nitroaromatic compounds can be identified unambiguously by their SERS spectra. Even the dominant bands containing nitro-group scissoring and symmetric stretching modes are significantly shifted by the difference in molecular structure.

Students Learning Physics While Lifting Themselves: A Simple Analysis of a Scissors Jack

ERIC Educational Resources Information Center

Haugland, Ole Anton

2017-01-01

Every time I have to jack up my car, I am a bit surprised by how slowly the scissors jack works the higher I raise it, and close to maximum height I need very little force to turn the crank. This agrees well with the principle of simple machines. Since I have to jack up my car at least twice a year to change between winter tires and summer tires,…

Commissioning a hobby cutting device for radiochromic film preparation.

PubMed

Zolfaghari, Somayeh; Francis, Kirby E; Kairn, Tanya; Crowe, Scott B

2017-06-01

In addition to a high spatial resolution and well characterised dose response, one of the major advantages of radiochromic film as a dosimeter is that sheets of film can be cut into pieces suitable for use as calibration films, and for in vivo and phantom measurements. The cutting of film is typically done using scissors or a guillotine, and this process can be time-consuming, limited in precision, requires extensive handling and does not allow holes to be cut from the film without cutting from an existing edge. This study investigated the use of a Brother ScanNCut hobby cutting system for EBT3 film preparation. The optimal operating parameters (blade size, pressure, speed) that resulted in precise cuts with minimal delamination at cut edges were identified using test cutting patterns. These parameters were then used to cut a large film insert for a stereotactic head phantom for comparison against an insert cut with scissors. While the hobby cutting system caused a wider region of delamination at the film edge (1.8 mm) compared to scissors (1 mm), the hobby cutting system was found to be able to produce reproducible cuts more efficiently and more accurately than scissors. The use of the hobby cutting system is recommended for complex phantom inserts (containing sharp corners or holes for alignment rods) or in situations where large numbers of film pieces need to be prepared.

The effect of opponent type on human performance in a three-alternative choice task.

PubMed

Lie, Celia; Baxter, Jennifer; Alsop, Brent

2013-10-01

Adult participants played computerised games of "Paper Scissors Rock". Participants in one group were told that they were playing against the computer, and those in the other group were told that they were playing against another participant in the adjacent room. The participant who won the most games would receive a $50 prize. For both groups however, the opponent's responses (paper, scissors, or rock) were generated by the computer, and the distribution of these responses was varied across four blocks of 126 trials. Results were analysed using the generalised matching law for the three possible pairs of alternatives (paper vs. scissors, paper vs. rock, and scissors vs. rock) across all participants in each group. Overall, significantly higher estimates of sensitivity to the distribution of opponent's responses were obtained from participants who were told their opponent was a computer compared to participants who were told their opponent was another participant. While adding to the existing literature showing that the generalised matching law is an adequate descriptor of human three-alternative choice behaviour, these findings show that external factors such as perceived opponent type can affect the efficacy of reinforcer contingencies on human behaviour. This suggests that generalising the results from tasks performed against a computer to real-life human-to-human interactions warrants some caution. Copyright © 2013 Elsevier B.V. All rights reserved.

Scissors Duct

NASA Image and Video Library

2007-06-26

Stennis Space Center engineers are preparing to conduct water tests on an updated version of the scissors duct component of the J-2X engine. Measuring about 2 feet long and about 8 inches in diameter, the duct on the J-2X predecessor, the J-2, connected its fuel turbo pumps to the flight vehicle's upper stage run tanks. According to NASA's J-2X project manager at SSC, Gary Benton, the water tests should establish the limits of the duct's ability to withstand vibration.

Characterization of spiraling patterns in spatial rock-paper-scissors games.

PubMed

Szczesny, Bartosz; Mobilia, Mauro; Rucklidge, Alastair M

2014-09-01

The spatiotemporal arrangement of interacting populations often influences the maintenance of species diversity and is a subject of intense research. Here, we study the spatiotemporal patterns arising from the cyclic competition between three species in two dimensions. Inspired by recent experiments, we consider a generic metapopulation model comprising "rock-paper-scissors" interactions via dominance removal and replacement, reproduction, mutations, pair exchange, and hopping of individuals. By combining analytical and numerical methods, we obtain the model's phase diagram near its Hopf bifurcation and quantitatively characterize the properties of the spiraling patterns arising in each phase. The phases characterizing the cyclic competition away from the Hopf bifurcation (at low mutation rate) are also investigated. Our analytical approach relies on the careful analysis of the properties of the complex Ginzburg-Landau equation derived through a controlled (perturbative) multiscale expansion around the model's Hopf bifurcation. Our results allow us to clarify when spatial "rock-paper-scissors" competition leads to stable spiral waves and under which circumstances they are influenced by nonlinear mobility.

Induced defences alter the strength and direction of natural selection on reproductive traits in common milkweed.

PubMed

Thompson, K A; Cory, K A; Johnson, M T J

2017-06-01

Evolutionary biologists have long sought to understand the ecological processes that generate plant reproductive diversity. Recent evidence indicates that constitutive antiherbivore defences can alter natural selection on reproductive traits, but it is unclear whether induced defences will have the same effect and whether reduced foliar damage in defended plants is the cause of this pattern. In a factorial field experiment using common milkweed, Asclepias syriaca L., we induced plant defences using jasmonic acid (JA) and imposed foliar damage using scissors. We found that JA-induced plants experienced selection for more inflorescences that were smaller in size (fewer flowers), whereas control plants only experienced a trend towards selection for larger inflorescences (more flowers); all effects were independent of foliar damage. Our results demonstrate that induced defences can alter both the strength and direction of selection on reproductive traits, and suggest that antiherbivore defences may promote the evolution of plant reproductive diversity. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Infrared laser spectroscopy of the n-propyl and i-propyl radicals: Stretch-bend Fermi coupling in the alkyl CH stretch region

DOE PAGES

Franke, Peter R.; Tabor, Daniel P.; Moradi, Christopher P.; ...

2016-12-13

The n-propyl and i-propyl radicals were generated in the gas phase via pyrolysis of n-butyl nitrite [CH 3(CH 2) 3ONO] and i-butyl nitrite [(CH 3) 2CHCH 2ONO], respectively. Nascent radicals were promptly solvated by a beam of He nanodroplets, and the infrared spectra of the radicals were recorded in the CH stretching region. Several previously unreported bands are observed between 2800 and 3150 cm –1. The CH stretching modes observed above 3000 cm –1 are in excellent agreement with CCSD(T) anharmonic frequencies computed using second-order vibrational perturbation theory. However, between 2800 and 3000 cm –1, the spectra of n- andmore » i-propyl radicals become congested and difficult to assign due to the presence of multiple anharmonic resonance polyads. To model the spectrally congested region, Fermi and Darling-Dennison resonances are treated explicitly using “dressed” Hamiltonians and CCSD(T) quartic force fields in the normal mode representation, and the agreement with experiment is less than satisfactory. Computations employing local mode effective Hamiltonians reveal the origin of the spectral congestion to be strong coupling between the high frequency CH stretching modes and the lower frequency CH n bending/scissoring motions. The most significant coupling is between stretches and bends localized on the same CH 2/CH 3 group. As a result, spectral simulations using the local mode approach are in excellent agreement with experiment.« less

Infrared laser spectroscopy of the n-propyl and i-propyl radicals: Stretch-bend Fermi coupling in the alkyl CH stretch region

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

Franke, Peter R.; Tabor, Daniel P.; Moradi, Christopher P.

The n-propyl and i-propyl radicals were generated in the gas phase via pyrolysis of n-butyl nitrite [CH 3(CH 2) 3ONO] and i-butyl nitrite [(CH 3) 2CHCH 2ONO], respectively. Nascent radicals were promptly solvated by a beam of He nanodroplets, and the infrared spectra of the radicals were recorded in the CH stretching region. Several previously unreported bands are observed between 2800 and 3150 cm –1. The CH stretching modes observed above 3000 cm –1 are in excellent agreement with CCSD(T) anharmonic frequencies computed using second-order vibrational perturbation theory. However, between 2800 and 3000 cm –1, the spectra of n- andmore » i-propyl radicals become congested and difficult to assign due to the presence of multiple anharmonic resonance polyads. To model the spectrally congested region, Fermi and Darling-Dennison resonances are treated explicitly using “dressed” Hamiltonians and CCSD(T) quartic force fields in the normal mode representation, and the agreement with experiment is less than satisfactory. Computations employing local mode effective Hamiltonians reveal the origin of the spectral congestion to be strong coupling between the high frequency CH stretching modes and the lower frequency CH n bending/scissoring motions. The most significant coupling is between stretches and bends localized on the same CH 2/CH 3 group. As a result, spectral simulations using the local mode approach are in excellent agreement with experiment.« less

Collective excitation frequencies and stationary states of trapped dipolar Bose-Einstein condensates in the Thomas-Fermi regime

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

Bijnen, R. M. W. van; Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1; Parker, N. G.

We present a general method for obtaining the exact static solutions and collective excitation frequencies of a trapped Bose-Einstein condensate (BEC) with dipolar atomic interactions in the Thomas-Fermi regime. The method incorporates analytic expressions for the dipolar potential of an arbitrary polynomial density profile, thereby reducing the problem of handling nonlocal dipolar interactions to the solution of algebraic equations. We comprehensively map out the static solutions and excitation modes, including non-cylindrically-symmetric traps, and also the case of negative scattering length where dipolar interactions stabilize an otherwise unstable condensate. The dynamical stability of the excitation modes gives insight into the onsetmore » of collapse of a dipolar BEC. We find that global collapse is consistently mediated by an anisotropic quadrupolar collective mode, although there are two trapping regimes in which the BEC is stable against quadrupole fluctuations even as the ratio of the dipolar to s-wave interactions becomes infinite. Motivated by the possibility of a fragmented condensate in a dipolar Bose gas due to the partially attractive interactions, we pay special attention to the scissors modes, which can provide a signature of superfluidity, and identify a long-range restoring force which is peculiar to dipolar systems. As part of the supporting material for this paper we provide the computer program used to make the calculations, including a graphical user interface.« less

Investigation of the Structure, Optical and Electrical Properties of Lithium Perchlorate Doped Polyaniline Composite: Aloe Vera Used as a Bio-Plasticizer

NASA Astrophysics Data System (ADS)

Yesappa, L.; Niranjana, M.; Ashokkumar, S. P.; Vijeth, H.; Sharanappa, Chapi; Raghu, S.; Devendrappa, H.

2017-12-01

Bio-plasticizer based polyaniline (PANI)/lithium perchlorate (LiClO4) composites were synthesized by the facile in situ method. The composites were characterized using the Fourier transform infrared spectroscopy (FT-IR) to identify the chemical interactions. A band appeared at 1502 cm-1 due to the presence of the -H2CO- group and CH2 scissor mode vibration for the PAL15% composite. This considerable change in the morphology of LiClO4 homogeneous dispersion in a PANI matrix was investigated by scanning electron microscopy (SEM). The UV-Visible absorption (UV-Vis) showed 300-400 nm attributed to the π- π* transition and exhibited a red shift from 535 nm to 617 nm in the visible region, indicating a decrease in band gap. The variations in dielectric constant with the addition of lithium perchlorate (LiClO4) at different temperatures and in the frequency range of 20 Hz-1 MHz were assessed through impedance analysis. The temperature dependent electrical conductivity increased with increasing temperature as well as dopant concentration. High conductivity of 1.41 × 10-3 S/cm corresponding to activation energy of 0.02 eV and 2.95 eV optical band gap for 15 wt.% of LiClO4 concentration was observed. The cyclic voltammetry measurement revealed a typical rectangular shape of the integral area, suggesting that the composite has strong electrochemical strength and is a possible candidate for electrochemical super capacitor and solar cell applications.

Ultrasonic scissors-assisted 'open-book' thyroidectomy in massive goiter compressing airway and causing unilateral vocal cord paralysis.

PubMed

M, Irfan; Yaroko, Ali Ango; S M, Najeb; Periasamy, Centilnathan

2013-04-01

A massive goiter may constrict the trachea resulting in shortness of breath. Recurrent laryngeal nerve compression may cause vocal cord paralysis. We highlight a case of a 62- year-old female with a 30 year history of an anterior neck swelling gradually increasing in size. She presented with acute symptoms of upper airway obstruction and voice changes. Emergency thyroidectomy was performed by dividing the middle part of the gland using ultrasonic scissors. The recovery was uneventful and the patient regained normal vocal cord function post operatively.

Feasibility of New Technology to Comprehensively Characterize Air Emissions from Full Scale Open Burning and Open Detonation

DTIC Science & Technology

2010-12-01

balloon and ATV winch system (right). 9 Figure 2-4. Scissor lift (left) and instrumentation on the scissor lift (right). 10 Figure 2-5. Concrete burn...indoor facility (#1376), bunkers, a gravel/sand detonation area for open detonation tests (~330 ft × 165 ft, ~100 m ×50 m) and a concrete burn pad... Concrete burn pad with six reusable sheet steel pans showing a burn of 100 lb (45.5 kg) of M1 propellant. 2.2.3.2 Open Detonation Based on several pre

Endoscope and System and Method of Operation Thereof

NASA Technical Reports Server (NTRS)

Manohara, Harish M. (Inventor); Liao, Anna (Inventor); Bae, Youngsam (Inventor); Shahinian, Hrayr Karnig (Inventor)

2017-01-01

An endoscope including a rigid section having opposed first and second ends and an opening situated between the first and second ends, the rigid section defining a longitudinal axis; a handle portion coupled to a first end of the rigid section and having first and second scissor-type handles suitable for grasping by a user; and a base part situated at the second end of the rigid section and coupled to the first handle of the scissor-type handles such that displacement of the first handle causes a rotation of the base part.

Endoscope and System and Method of Operation Thereof

NASA Technical Reports Server (NTRS)

Manohara, Harish M. (Inventor); Liao, Anna (Inventor); Bae, Youngsam (Inventor); Shahinian, Hrayr Karnig (Inventor)

2012-01-01

An endoscope including a rigid section having opposed first and second ends and an opening situated between the first and second ends, the rigid section defining a longitudinal axis; a handle portion coupled to a first end of the rigid section and having first and second scissor-type handles suitable for grasping by a user; and a base part situated at the second end of the rigid section and coupled to the first handle of the scissor-type handles such that displacement of the first handle causes a rotation of the base part.

Infrared Laser Spectroscopy of the n-PROPYL and i-PROPYL Radicals in Helium Droplets: Significant Bend-Stretch Coupling Revealed in the CH Stretch Region

NASA Astrophysics Data System (ADS)

Moradi, Christopher P.; Douberly, Gary E.; Tabor, Daniel P.; Sibert, Edwin

2016-06-01

The n-propyl and i-propyl radicals were generated in the gas phase via pyrolysis of n-butyl nitrite (CH3(CH2)3ONO) and i-butyl nitrite (CH3CH(CH3)CH2ONO) precursors, respectively. Nascent radicals were promptly solvated by a beam of He nanodroplets, and the infrared spectra of the radicals were recorded in the C-H stretching region. In addition to three vibrations of n-propyl previously measured in an Ar matrix, we observe many unreported bands between 2800 and 3150 wn, which we attribute to propyl radicals. The C-H stretching modes observed above 2960 wn for both radicals are in excellent agreement with anharmonic frequencies computed using VPT2. Between 2800 and 2960 wn, however, the spectra of n-propyl and i-propyl radicals become quite congested and difficult to assign due to the presence of multiple anharmonic resonances. Computations employing a local mode Hamiltonian reveal the origin of the spectral congestion to be strong coupling between the high frequency C-H stretching modes and the lower frequency bending/scissoring motions. The only significant local coupling is between stretches and bends on the same CH2/CH3 group.

Emergency cricothyrotomy-a comparative study of different techniques in human cadavers.

PubMed

Schober, Patrick; Hegemann, Martina C; Schwarte, Lothar A; Loer, Stephan A; Noetges, Peter

2009-02-01

Emergency cricothyrotomy is the final lifesaving option in "cannot intubate-cannot ventilate" situations. Fast, efficient and safe management is indispensable to reestablish oxygenation, thus the quickest, most reliable and safest technique should be used. Several cricothyrotomy techniques exist, which can be grouped into two categories: anatomical-surgical and puncture. We studied success rate, tracheal tube insertion time and complications of different techniques, including a novel cricothyrotomy scissors technique in human cadavers. Sixty-three inexperienced health care providers were randomly assigned to apply either an anatomical-surgical technique (standard surgical technique, n=18; novel cricothyrotomy scissors technique, n=14) or a puncture technique (catheter-over-needle technique, n=17; wire-guided technique, n=14). Airway access was almost always successful with the anatomical-surgical techniques (success rate in standard surgical group 94%, scissors group 100%). In contrast, the success rate was smaller (p<0.05) with the puncture techniques (catheter-over-needle group 82%, wire-guided technique 71%). Tracheal tube insertion time was faster overall (p<0.05) with anatomical-surgical techniques (standard surgical 78s [54-135], novel cricothyrotomy scissors technique 60s [42-82]; median [IQR]) than with puncture techniques (catheter-over-needle technique 74s [48-145], wire-guided technique 135s [116-307]). We observed fewer complications with anatomical-surgical techniques than with puncture techniques (p<0.001). In inexperienced health care personnel, anatomical-surgical techniques showed a higher success rate, a faster tracheal tube insertion time and a lower complication rate compared with puncture techniques, suggesting that they may be the techniques of choice in emergencies.

An Affordable Microsurgical Training System for a Beginning Neurosurgeon: How to Realize the Self-Training Laboratory.

PubMed

Chung, Sang-Bong; Ryu, Jiwook; Chung, Yeongu; Lee, Sung Ho; Choi, Seok Keun

2017-09-01

To provide detailed information about how to realize a self-training laboratory with cost-effective microsurgical instruments, especially pertinent for the novice trainee. Our training model is designed to allow the practice of the microsurgery skills in an efficient and cost-effective manner. A used stereoscopic microscope is prepared for microsurgical training. A sufficient working distance for microsurgical practice is obtained by attaching an auxiliary objective lens. The minimum instrument list includes 2 jeweler's forceps, iris scissors, and alligator clips. The iris scissors and alligator clip provide good alternatives to micro-scissors and microvascular clamp. The short time needed to set up the microscope and suture the gauze with micro-forceps makes the training model suitable for daily practice. It takes about 15 minutes to suture 10 neighboring fibers of the gauze with 10-0 nylon; thus, training can be completed more quickly. We have developed an inexpensive and efficient micro-anastomosis training system using a stereoscopic microscope and minimal micro-instruments. Especially useful for novice trainees, this system provides high accessibility for microsurgical training. Copyright © 2017 Elsevier Inc. All rights reserved.

Angular Momentum of a Bose-Einstein Condensate in a Synthetic Rotational Field

NASA Astrophysics Data System (ADS)

Qu, Chunlei; Stringari, Sandro

2018-05-01

By applying a position-dependent detuning to a spin-orbit-coupled Hamiltonian with equal Rashba and Dresselhaus coupling, we exploit the behavior of the angular momentum of a harmonically trapped Bose-Einstein condensed atomic gas and discuss the distinctive role of its canonical and spin components. By developing the formalism of spinor hydrodynamics, we predict the precession of the dipole oscillation caused by the synthetic rotational field, in analogy with the precession of the Foucault pendulum, the excitation of the scissors mode, following the sudden switching off of the detuning, and the occurrence of Hall-like effects. When the detuning exceeds a critical value, we observe a transition from a vortex free, rigidly rotating quantum gas to a gas containing vortices with negative circulation which results in a significant reduction of the total angular momentum.

An unusual intracranial metallic foreign bodies and panhypopituitarism.

PubMed

Lakouichmi, Mohammed; Baïzri, Hicham; Mouhsine, Abdelilah; Boukhira, Abderrahmane; Akhaddar, Ali

2014-01-01

A 49 years old man, with a history of aggression at the age of 18 years by a pair of scissors, who consulted for unilateral migraine headaches look straight. Paraclinical explorations concluded that trauma to anterior pituitary by a metallic foreign body from the right nostril to the sella, responsible for panhypopituitarism and sinusitis. The headaches are frequent causes of consultation, often treated symptomatically but rarely explored. The direct trauma to the pituitary gland, by a metallic foreign body, is exceptional. We report the case of neglected panhypopituitarism, discovered 31 years after injury with a pair of scissors.

An unusual intracranial metallic foreign bodies and panhypopituitarism

PubMed Central

Lakouichmi, Mohammed; Baïzri, Hicham; Mouhsine, Abdelilah; Boukhira, Abderrahmane; Akhaddar, Ali

2014-01-01

A 49 years old man, with a history of aggression at the age of 18 years by a pair of scissors, who consulted for unilateral migraine headaches look straight. Paraclinical explorations concluded that trauma to anterior pituitary by a metallic foreign body from the right nostril to the sella, responsible for panhypopituitarism and sinusitis. The headaches are frequent causes of consultation, often treated symptomatically but rarely explored. The direct trauma to the pituitary gland, by a metallic foreign body, is exceptional. We report the case of neglected panhypopituitarism, discovered 31 years after injury with a pair of scissors. PMID:25667695

How directional mobility affects coexistence in rock-paper-scissors models

NASA Astrophysics Data System (ADS)

Avelino, P. P.; Bazeia, D.; Losano, L.; Menezes, J.; de Oliveira, B. F.; Santos, M. A.

2018-03-01

This work deals with a system of three distinct species that changes in time under the presence of mobility, selection, and reproduction, as in the popular rock-paper-scissors game. The novelty of the current study is the modification of the mobility rule to the case of directional mobility, in which the species move following the direction associated to a larger (averaged) number density of selection targets in the surrounding neighborhood. Directional mobility can be used to simulate eyes that see or a nose that smells, and we show how it may contribute to reduce the probability of coexistence.

How directional mobility affects coexistence in rock-paper-scissors models.

PubMed

Avelino, P P; Bazeia, D; Losano, L; Menezes, J; de Oliveira, B F; Santos, M A

2018-03-01

This work deals with a system of three distinct species that changes in time under the presence of mobility, selection, and reproduction, as in the popular rock-paper-scissors game. The novelty of the current study is the modification of the mobility rule to the case of directional mobility, in which the species move following the direction associated to a larger (averaged) number density of selection targets in the surrounding neighborhood. Directional mobility can be used to simulate eyes that see or a nose that smells, and we show how it may contribute to reduce the probability of coexistence.

Development and effect of a cognitive enhancement gymnastics program for elderly people with dementia

PubMed Central

Han, Yoon-Soo; Araki, Tatsuo; Lee, Pil-Young; Choi, Jung-Hyun; Kwon, In-Seon; Kwon, Ki-Nam; Kim, Ji-Youn

2016-01-01

The purpose of this study was to develop a cognitive enhancement gymnastics program for the elderly with dementia and to verify its effect. The study was conducted on 27 people with dementia being treated in a dementia day care center in Incheon city. No statistically significant differences were found in the measures Mini-Mental State Examination for Dementia Screening (MMSE-DS), Short Geriatric Depression Scale (SGDS), Seoul Activities of Daily Living (S-ADL), or rock-paper-scissors. However, the MMSE-DS and rock-paper-scissors showed improvement after 12 weeks. PMID:27656632

Development of a dual joystick-controlled laser trapping and cutting system for optical micromanipulation of chromosomes inside living cells.

PubMed

Harsono, Marcellinus S; Zhu, Qingyuan; Shi, Linda Z; Duquette, Michelle; Berns, Michael W

2013-02-01

A multi-joystick robotic laser microscope system used to control two optical traps (tweezers) and one laser scissors has been developed for subcellular organelle manipulation. The use of joysticks has provided a "user-friendly" method for both trapping and cutting of organelles such as chromosomes in live cells. This innovative design has enabled the clean severing of chromosome arms using the laser scissors as well as the ability to easily hold and pull the severed arm using the laser tweezers. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Clustering Effect on the Dynamics in a Spatial Rock-Paper-Scissors System

NASA Astrophysics Data System (ADS)

Hashimoto, Tsuyoshi; Sato, Kazunori; Ichinose, Genki; Miyazaki, Rinko; Tainaka, Kei-ichi

2018-01-01

The lattice dynamics for rock-paper-scissors games is related to population theories in ecology. In most cases, simulations are performed by local and global interactions. It is known in the former case that the dynamics is usually stable. We find two types of non-random distributions in the stationary state. One is a cluster formation of endangered species: when the density of a species approaches zero, its clumping degree diverges to infinity. The other is the strong aggregations of high-density species. Such spatial pattern formations play important roles in population dynamics.

Influence of the number of cycles on shear fatigue strength of resin composite bonded to enamel and dentin using dental adhesives in self-etching mode.

PubMed

Tsujimoto, Akimasa; Barkmeier, Wayne W; Erickson, Robert L; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

2018-01-30

The influence of the number of cycles on shear fatigue strength to enamel and dentin using dental adhesives in self-etch mode was investigated. A two-step self-etch adhesive and two universal adhesives were used to bond to enamel and dentin in self-etch mode. Initial shear bond strength and shear fatigue strength to enamel and dentin using the adhesive in self-etch mode were determined. Fatigue testing was used with 20 Hz frequency and cycling periods of 50,000, 100,000 and 1,000,000 cycles, or until failure occurred. For each of the cycling periods, there was no significant difference in shear fatigue strength across the cycling periods for the individual adhesives. Differences in shear fatigue strength were found between the adhesives within the cycling periods. Regardless of the adhesive used in self-etch mode for bonding to enamel or dentin, shear fatigue strength was not influenced by the number of cycles used for shear fatigue strength testing.

Electrosurgery reduces blood loss and immediate postoperative inflammation compared to cold instruments for midline celiotomy in dogs: A randomized controlled trial

PubMed Central

Meakin, Lee B.; Murrell, Jo C.; Doran, Ivan C. P.; Knowles, Toby G.; Tivers, Michael S.

2017-01-01

Abstract Objectives To compare the use of an electrosurgical device with traditional cold instruments (scalpel and scissors) for midline celiotomy incision. Study design Prospective randomized controlled clinical trial. Sample population: One hundred and twenty client‐owned dogs undergoing abdominal surgery. Methods Dogs were prospectively recruited and randomized to receive electroincision or cold instrument incision. For cold incision, surgeons used basic surgical instruments including scalpel and scissors. For electroincision, surgeons only used the electrosurgical device in cutting mode. Time for the approach, blood loss, and the incision length were recorded. A blinded observer assessed pain and incision redness, swelling, and discharge at 24 and 48 hours postoperative (graded 0‐3). Owner assessment of incision healing was recorded by telephone interview. Results Blood loss during surgery was significantly lower for electroincision (mean 0.7, SD 1.7 mL) than cold incision (mean 3.0, SD 4.3 mL, P < .0001) with no significant difference in incision length or time for approach. Electroincision was associated with significantly less incision redness (cold median 1, range 0‐3; electroincision median 0, range 0‐2, P = .02) and less incision discharge (cold median 0.5 range 0‐3; electroincision median 0, range 0‐1, P = .006) at 24 hours postoperative. There was no significant difference in pain scores or incision healing in dogs receiving the two techniques. No incisional hernias were reported. A surgical site infection occurred in 1 dog (cold incision). Conclusions Electroincision for a celiotomy approach in the dog reduces blood loss, and incision redness and discharge in the immediate postoperative period without affecting the occurrence of wound complications such as infection and dehiscence (including linea alba). PMID:28314089

[EFFECTIVENESS COMPARISON OF PROXIMAL FEMORAL NAIL ANTI-ROTATION IN SUPINE "SCISSORS" POSITION AND IN LITHOTOMY POSITION TO TREAT FEMORAL INTERTROCHANTERIC FRACTURES OF OLD PATIENTS].

PubMed

Du, Shihao; Yin, Fei; Wei, Xuming; Song, Sheng; Gu, Sanjun; Sun, Zhenzhong; Rui, Yongjun

2016-02-01

To compare the effectiveness of proximal femoral nail anti-rotation (PFNA) between in the supine "scissors" position and in the lithotomy position for treating femoral intertrochanteric fractures of old patients. A retrospective study was performed on 58 patients with femoral intertrochanteric fractures treated with PFNA between January 2013 and January 2015. Fracture was treated with PFNA in the lithotomy position in 28 cases (group A) and in the supine "scissors" position in 30 cases (group B). There was no significant difference in gender, age, side, cause of injury, fracture type, and interval from injury to operation between 2 groups (P>0.05). The incision length, operation time, perspective times, intraoperative blood loss, complications, and fracture healing time were recorded; Harris hip score was used to access the effectiveness. The wound healed by first intention without infection, pressure sores, deep vein thrombosis of lower extremity, and other complications. There was no significant difference in incision length between 2 groups (t=1.313, P=0.212). Group B was significantly better than group A in operation time, perspective times, and intraoperative blood loss (P<0.05). All patients were followed up 10-31 months (mean, 15.3 months). Stretch injury at normal side and perineal discomfort occurred in 1 case and 5 cases of group A respectively, and no nonunion and other complications was observed in the other patients. There was no significant difference in fracture healing time and Harris hip score at last follow-up between 2 groups (P>0.05). PFNA in the supine "scissors" position has exact effectiveness and advantages of shorter operation time, less intraoperative blood loss, less perspective times, and fewer complications.

Mechanical Behavior of Brittle Rock-Like Specimens with Pre-existing Fissures Under Uniaxial Loading: Experimental Studies and Particle Mechanics Approach

NASA Astrophysics Data System (ADS)

Cao, Ri-hong; Cao, Ping; Lin, Hang; Pu, Cheng-zhi; Ou, Ke

2016-03-01

Joints and fissures with similar orientation or characteristics are common in natural rocks; the inclination and density of the fissures affect the mechanical properties and failure mechanism of the rock mass. However, the strength, crack coalescence pattern, and failure mode of rock specimens containing multi-fissures have not been studied comprehensively. In this paper, combining similar material testing and discrete element numerical method (PFC2D), the peak strength and failure characteristics of rock-like materials with multi-fissures are explored. Rock-like specimens were made of cement and sand and pre-existing fissures created by inserting steel shims into cement mortar paste and removing them during curing. The peak strength of multi-fissure specimens depends on the fissure angle α (which is measured counterclockwise from horizontal) and fissure number ( N f). Under uniaxial compressional loading, the peak strength increased with increasing α. The material strength was lowest for α = 25°, and highest for α = 90°. The influence of N f on the peak strength depended on α. For α = 25° and 45°, N f had a strong effect on the peak strength, while for higher α values, especially for the 90° sample, there were no obvious changes in peak strength with different N f. Under uniaxial compression, the coalescence modes between the fissures can be classified into three categories: S-mode, T-mode, and M-mode. Moreover, the failure mode can be classified into four categories: mixed failure, shear failure, stepped path failure, and intact failure. The failure mode of the specimen depends on α and N f. The peak strength and failure modes in the numerically simulated and experimental results are in good agreement.

Hydrolysis mechanisms of BNPP mediated by facial copper(II) complexes bearing single alkyl guanidine pendants: cooperation between the metal centers and the guanidine pendants.

PubMed

Zhang, Xuepeng; Liu, Xueping; Phillips, David Lee; Zhao, Cunyuan

2016-01-28

The hydrolysis mechanisms of DNA dinucleotide analogue BNPP(-) (bis(p-nitrophenyl) phosphate) catalyzed by mononuclear/dinuclear facial copper(ii) complexes bearing single alkyl guanidine pendants were investigated using density functional theory (DFT) calculations. Active catalyst forms have been investigated and four different reaction modes are proposed accordingly. The [Cu2(L(1))2(μ-OH)](3+) (L(1) is 1-(2-guanidinoethyl)-1,4,7-triazacyclononane) complex features a strong μ-hydroxo mediated antiferromagnetic coupling between the bimetallic centers and the corresponding more stable open-shell singlet state. Three different reaction modes involving two catalysts and a substrate were proposed for L(1) entries and the mode 1 in which an inter-complex nucleophilic attack by a metal bound hydroxide was found to be more favorable. In the L(3)-involved reactions (L(3) is 1-(4-guanidinobutyl)-1,4,7-triazacyclononane), the reaction mode in which an in-plane intracomplex scissoring-like nucleophilic attack by a Cu(ii)-bound hydroxide was found to be more competitive. The protonated guanidine pendants in each proposed mechanism were found to play crucial roles in stabilizing the reaction structures via hydrogen bonds and in facilitating the departure of the leaving group via electrostatic attraction. The calculated results are consistent with the experimental observations that the Cu(ii)-L(3) complexes are hydrolytically more favorable than their L(1)-involved counterparts.

The rock-paper-scissors game

NASA Astrophysics Data System (ADS)

Zhou, Hai-Jun

2016-04-01

Rock-Paper-Scissors (RPS), a game of cyclic dominance, is not merely a popular children's game but also a basic model system for studying decision-making in non-cooperative strategic interactions. Aimed at students of physics with no background in game theory, this paper introduces the concepts of Nash equilibrium and evolutionarily stable strategy, and reviews some recent theoretical and empirical efforts on the non-equilibrium properties of the iterated RPS, including collective cycling, conditional response patterns and microscopic mechanisms that facilitate cooperation. We also introduce several dynamical processes to illustrate the applications of RPS as a simplified model of species competition in ecological systems and price cycling in economic markets.

Cyclic dominance in evolutionary games: a review

PubMed Central

Szolnoki, Attila; Mobilia, Mauro; Jiang, Luo-Luo; Szczesny, Bartosz; Rucklidge, Alastair M.; Perc, Matjaž

2014-01-01

Rock is wrapped by paper, paper is cut by scissors and scissors are crushed by rock. This simple game is popular among children and adults to decide on trivial disputes that have no obvious winner, but cyclic dominance is also at the heart of predator–prey interactions, the mating strategy of side-blotched lizards, the overgrowth of marine sessile organisms and competition in microbial populations. Cyclical interactions also emerge spontaneously in evolutionary games entailing volunteering, reward, punishment, and in fact are common when the competing strategies are three or more, regardless of the particularities of the game. Here, we review recent advances on the rock–paper–scissors (RPS) and related evolutionary games, focusing, in particular, on pattern formation, the impact of mobility and the spontaneous emergence of cyclic dominance. We also review mean-field and zero-dimensional RPS models and the application of the complex Ginzburg–Landau equation, and we highlight the importance and usefulness of statistical physics for the successful study of large-scale ecological systems. Directions for future research, related, for example, to dynamical effects of coevolutionary rules and invasion reversals owing to multi-point interactions, are also outlined. PMID:25232048

Cyclic dominance in evolutionary games: a review.

PubMed

Szolnoki, Attila; Mobilia, Mauro; Jiang, Luo-Luo; Szczesny, Bartosz; Rucklidge, Alastair M; Perc, Matjaž

2014-11-06

Rock is wrapped by paper, paper is cut by scissors and scissors are crushed by rock. This simple game is popular among children and adults to decide on trivial disputes that have no obvious winner, but cyclic dominance is also at the heart of predator-prey interactions, the mating strategy of side-blotched lizards, the overgrowth of marine sessile organisms and competition in microbial populations. Cyclical interactions also emerge spontaneously in evolutionary games entailing volunteering, reward, punishment, and in fact are common when the competing strategies are three or more, regardless of the particularities of the game. Here, we review recent advances on the rock-paper-scissors (RPS) and related evolutionary games, focusing, in particular, on pattern formation, the impact of mobility and the spontaneous emergence of cyclic dominance. We also review mean-field and zero-dimensional RPS models and the application of the complex Ginzburg-Landau equation, and we highlight the importance and usefulness of statistical physics for the successful study of large-scale ecological systems. Directions for future research, related, for example, to dynamical effects of coevolutionary rules and invasion reversals owing to multi-point interactions, are also outlined. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Unifying measurement of Pu 239 ( n , γ ) in the keV to MeV energy regime

DOE PAGES

Mosby, S.; Bredeweg, T. A.; Couture, A.; ...

2018-04-23

A single, unifying measurement of the 239Pu capture cross section from 1 keV to 1.3 MeV has been performed for the first time using the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center (LANSCE). The experimental method combines a prior experiment's characterization of prompt fission γ rays in conjunction with a fission tagging detector with a separate experiment using a thick 239Pu sample to extract the neutron capture cross section in ratio to 239Pu (n, f). We have made new predictions of the capture cross section taking into account recent results for the M1more » scissors mode present in other actinides. The results show deviations from current evaluations which are 30% higher at the highest energies, and will be used to improve calculations relevant for several applications.« less

Unifying measurement of 239Pu(n ,γ ) in the keV to MeV energy regime

NASA Astrophysics Data System (ADS)

Mosby, S.; Bredeweg, T. A.; Couture, A.; Jandel, M.; Kawano, T.; Ullmann, J. L.; Henderson, R. A.; Wu, C. Y.

2018-04-01

A single, unifying measurement of the 239Pu capture cross section from 1 keV to 1.3 MeV has been performed for the first time using the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center (LANSCE). The experimental method combines a prior experiment's characterization of prompt fission γ rays in conjunction with a fission tagging detector with a separate experiment using a thick 239Pu sample to extract the neutron capture cross section in ratio to 239Pu(n ,f ) . We have made new predictions of the capture cross section taking into account recent results for the M 1 scissors mode present in other actinides. The results show deviations from current evaluations which are 30% higher at the highest energies, and will be used to improve calculations relevant for several applications.

Remembered study mode: support for the distinctiveness account of the production effect.

PubMed

Ozubko, Jason D; Major, Jennifer; MacLeod, Colin M

2014-01-01

The production effect is the finding that words spoken aloud at study are subsequently remembered better than are words read silently at study. According to the distinctiveness account, aloud words are remembered better because the act of speaking those words aloud is encoded and later recovery of this information can be used to infer that those words were studied. An alternative account (the strength-based account) is that memory strength is simply greater for words read aloud. To discriminate these two accounts, we investigated study mode judgements (i.e., "aloud"/"silent"/"new" ratings): The strength-based account predicts that "aloud" responses should positively correlate with memory strength, whereas the distinctiveness account predicts that accuracy of study mode judgements will be independent of memory strength. Across three experiments, where the strength of some silent words was increased by repetition, study mode was discriminable regardless of strength-even when the strength of aloud and repeated silent items was equivalent. Consistent with the distinctiveness account, we conclude that memory for "aloudness" is independent of memory strength and a likely candidate to explain the production effect.

Skin lesion removal

MedlinePlus

... benign; Cryosurgery - skin, benign; BCC - removal; Basal cell cancer - removal; Actinic keratosis - removal; Wart - removal; Squamous cell - removal; Mole - removal; Nevus - removal; Nevi - removal; Scissor ...

Nonlinear dynamics of the rock-paper-scissors game with mutations.

PubMed

Toupo, Danielle F P; Strogatz, Steven H

2015-05-01

We analyze the replicator-mutator equations for the rock-paper-scissors game. Various graph-theoretic patterns of mutation are considered, ranging from a single unidirectional mutation pathway between two of the species, to global bidirectional mutation among all the species. Our main result is that the coexistence state, in which all three species exist in equilibrium, can be destabilized by arbitrarily small mutation rates. After it loses stability, the coexistence state gives birth to a stable limit cycle solution created in a supercritical Hopf bifurcation. This attracting periodic solution exists for all the mutation patterns considered, and persists arbitrarily close to the limit of zero mutation rate and a zero-sum game.

Comparison of enamel bond fatigue durability of universal adhesives and two-step self-etch adhesives in self-etch mode.

PubMed

Tsujimoto, Akimasa; Barkmeier, Wayne W; Hosoya, Yumiko; Nojiri, Kie; Nagura, Yuko; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

2017-10-01

To comparatively evaluate universal adhesives and two-step self-etch adhesives for enamel bond fatigue durability in self-etch mode. Three universal adhesives (Clearfil Universal Bond; G-Premio Bond; Scotchbond Universal Adhesive) and three two-step self-etch adhesives (Clearfil SE Bond; Clearfil SE Bond 2; OptiBond XTR) were used. The initial shear bond strength and shear fatigue strength of the adhesive to enamel in self-etch mode were determined. The initial shear bond strengths of the universal adhesives to enamel in self-etch mode was significantly lower than those of two-step self-etch adhesives and initial shear bond strengths were not influenced by type of adhesive in each adhesive category. The shear fatigue strengths of universal adhesives to enamel in self-etch mode were significantly lower than that of Clearfil SE Bond and Clearfil SE Bond 2, but similar to that OptiBond XTR. Unlike two-step self-etch adhesives, the initial shear bond strength and shear fatigue strength of universal adhesives to enamel in self-etch mode was not influenced by the type of adhesive. This laboratory study showed that the enamel bond fatigue durability of universal adhesives was lower than Clearfil SE Bond and Clearfil SE Bond 2, similar to Optibond XTR, and was not influenced by type of adhesive, unlike two-step self-etch adhesives.

Negative outcomes evoke cyclic irrational decisions in Rock, Paper, Scissors.

PubMed

Dyson, Benjamin James; Wilbiks, Jonathan Michael Paul; Sandhu, Raj; Papanicolaou, Georgios; Lintag, Jaimie

2016-02-04

Rock, Paper, Scissors (RPS) represents a unique gaming space in which the predictions of human rational decision-making can be compared with actual performance. Playing a computerized opponent adopting a mixed-strategy equilibrium, participants revealed a non-significant tendency to over-select Rock. Further violations of rational decision-making were observed using an inter-trial analysis where participants were more likely to switch their item selection at trial n + 1 following a loss or draw at trial n, revealing the strategic vulnerability of individuals following the experience of negative rather than positive outcome. Unique switch strategies related to each of these trial n outcomes were also identified: after losing participants were more likely to 'downgrade' their item (e.g., Rock followed by Scissors) but after drawing participants were more likely to 'upgrade' their item (e.g., Rock followed by Paper). Further repetition analysis revealed that participants were more likely to continue their specific cyclic item change strategy into trial n + 2. The data reveal the strategic vulnerability of individuals following the experience of negative rather than positive outcome, the tensions between behavioural and cognitive influences on decision making, and underline the dangers of increased behavioural predictability in other recursive, non-cooperative environments such as economics and politics.

Automatic imitation in a strategic context: players of rock–paper–scissors imitate opponents' gestures†

PubMed Central

Cook, Richard; Bird, Geoffrey; Lünser, Gabriele; Huck, Steffen; Heyes, Cecilia

2012-01-01

A compelling body of evidence indicates that observing a task-irrelevant action makes the execution of that action more likely. However, it remains unclear whether this ‘automatic imitation’ effect is indeed automatic or whether the imitative action is voluntary. The present study tested the automaticity of automatic imitation by asking whether it occurs in a strategic context where it reduces payoffs. Participants were required to play rock–paper–scissors, with the aim of achieving as many wins as possible, while either one or both players were blindfolded. While the frequency of draws in the blind–blind condition was precisely that expected at chance, the frequency of draws in the blind–sighted condition was significantly elevated. Specifically, the execution of either a rock or scissors gesture by the blind player was predictive of an imitative response by the sighted player. That automatic imitation emerges in a context where imitation reduces payoffs accords with its ‘automatic’ description, and implies that these effects are more akin to involuntary than to voluntary actions. These data represent the first evidence of automatic imitation in a strategic context, and challenge the abstraction from physical aspects of social interaction typical in economic and game theory. PMID:21775334

A genetic approach to the rock-paper-scissors game.

PubMed

Barreto, Wendell P; Marquitti, Flavia M D; de Aguiar, Marcus A M

2017-05-21

Polymorphisms are usually associated with defenses and mating strategies, affecting the individual's fitness. Coexistence of different morphs is, therefore, not expected, since the fittest morph should outcompete the others. Nevertheless, coexistence is observed in many natural systems. For instance, males of the side-blotched lizards (Uta stansburiana) present three morphs with throat colors orange, yellow and blue, which are associated with mating strategies and territorial behavior. The three male morphs compete for females in a system that is well described by the rock-paper-scissors dynamics of game theory. Previous studies have modeled the lizards as hermaphroditic populations whose individual's behavior were determined only by their phenotypes. Here we consider an extension of this dynamical system where diploidy and sexual reproduction are explicitly taken into account. Similarly to the lizards we represent the genetic system by a single locus with three alleles, o, y, and b in a diploid chromosome with dominance of o over y and of y over b. We show that this genotypic description of the dynamics results in the same equilibrium phenotype frequencies as the phenotypic models, but affects the stability of the system, changing the parameter region where coexistence of the three morphs is possible in a rock-paper-scissors game. Copyright © 2017 Elsevier Ltd. All rights reserved.

Upper-body strength gains from different modes of resistance training in women who are underweight and women who are obese.

PubMed

Mayhew, Jerry L; Smith, Abbie E; Arabas, Jana L; Roberts, B Scott

2010-10-01

The purpose of this study was to determine the degree of upper-body strength gained by college women who are underweight and those who are obese using different modes of resistance training. Women who were underweight (UWW, n = 93, weight = 49.3 ± 4.5 kg) and women who were obese (OBW, n = 73, weight = 94.0 ± 15.1 kg) were selected from a larger cohort based on body mass index (UWW ≤ 18.5 kg·m⁻²; OBW ≥ 30 kg·m⁻²). Subjects elected to train with either free weights (FW, n = 38), supine vertical bench press machine (n = 52) or seated horizontal bench press machine (n = 76) using similar linear periodization resistance training programs 3× per week for 12 weeks. Each participant was assessed for upper-body strength using FWs (general) and machine weight (specific) 1 repetition maximum bench press before and after training. Increases in general and mode-specific strength were significantly greater for OBW (5.2 ± 5.1 and 9.6 ± 5.1 kg, respectively) than for UWW (3.5 ± 4.1 and 7.2 ± 5.2 kg, respectively). General strength gains were not significantly different among the training modes. Mode-specific gains were significantly greater (p < 0.05) than general strength gains for all groups. In conclusion, various resistance training modes may produce comparable increases in general strength but will register greater gains if measured using the specific mode employed for training, regardless of the weight category of the individual.

21 CFR 884.1640 - Culdoscope and accessories.

Code of Federal Regulations, 2014 CFR

2014-04-01

... instruments include: lens cleaning brush, biopsy brush, clip applier (without clips), applicator, cannula... (noninflatable), snare, stylet, forceps, dissector, mechanical (noninflatable) scissors, and suction/irrigation...

21 CFR 884.1640 - Culdoscope and accessories.

Code of Federal Regulations, 2012 CFR

2012-04-01

... instruments include: lens cleaning brush, biopsy brush, clip applier (without clips), applicator, cannula... (noninflatable), snare, stylet, forceps, dissector, mechanical (noninflatable) scissors, and suction/irrigation...

21 CFR 884.1640 - Culdoscope and accessories.

Code of Federal Regulations, 2013 CFR

2013-04-01

... instruments include: lens cleaning brush, biopsy brush, clip applier (without clips), applicator, cannula... (noninflatable), snare, stylet, forceps, dissector, mechanical (noninflatable) scissors, and suction/irrigation...

Students Learning Physics While Lifting Themselves: A Simple Analysis of a Scissors Jack

NASA Astrophysics Data System (ADS)

Haugland, Ole Anton

2017-02-01

Every time I have to jack up my car, I am a bit surprised by how slowly the scissors jack works the higher I raise it, and close to maximum height I need very little force to turn the crank. This agrees well with the principle of simple machines. Since I have to jack up my car at least twice a year to change between winter tires and summer tires, I thought it was time to take a closer look at the physics behind the process. And like most physics teachers, I am always looking for new ideas for my teaching. In this note I will present a few ideas on how a jack can be a topic in physics teaching.

Life prediction methodology for ceramic components of advanced heat engines. Phase 1: Volume 2, Appendices

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

NONE

1995-03-01

This volume presents the following appendices: ceramic test specimen drawings and schematics, mixed-mode and biaxial stress fracture of structural ceramics for advanced vehicular heat engines (U. Utah), mode I/mode II fracture toughness and tension/torsion fracture strength of NT154 Si nitride (Brown U.), summary of strength test results and fractography, fractography photographs, derivations of statistical models, Weibull strength plots for fast fracture test specimens, and size functions.

Open-mode delamination stress concentrations in horseshoe and elliptic composite curved bars subjected to end forces

NASA Technical Reports Server (NTRS)

Ko, William L.; Jackson, Raymond H.

1990-01-01

The multilayer theory of anisotropic elasticity and a finite element method were used to analyze the open-mode delamination stress concentrations in horseshoe and elliptic laminated composite curved bars. Two types of laminations, solid laminations and sandwich laminations, were analyzed. It was found that the open-mode delamination stress concentration could be greatly increased in these two types of curved bars by decreasing their aspect ratios. The open-mode delamination stress concentration generated in the solid laminations was found to be far more severe than that generated in the sandwich laminations. The horseshoe curved bar may be used to determine both the open-mode delamination strength of solidly laminated composites and the open-mode debonding strength of sandwiched laminated composites. However, the elliptic curved bar is only good for determining the open-mode delamination strength of solidly laminated composites.

SMART micro-scissors with dual motors and OCT sensors (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yeo, Chaebeom; Jang, Seonjin; Park, Hyun-cheol; Gehlbach, Peter L.; Song, Cheol

2017-02-01

Various end-effectors of microsurgical instruments have been developed and studied. Also, many approaches to stabilize the tool-tip using robotics have been studied such as the steady hand robot system, Micron, and SMART system. In our previous study, the horizontal SMART micro-scissors with a common path swept source OCT distance and one linear piezoelectric (PZT) motor was demonstrated as a microsurgical system. Because the outer needle is connected with a mechanical handle and moved to engage the tool tip manually, the tool tip position is instantaneously changed during the engaging. The undesirable motion can make unexpected tissue damages and low surgical accuracy. In this study, we suggest a prototype horizontal SMART micro-scissors which has dual OCT sensors and two motors to improve the tremor cancellation. Dual OCT sensors provide two distance information. Front OCT sensor detects a distance from the sample surface to the tool tip. Rear OCT sensors gives current PZT motor movement, acting like a motor encoder. The PZT motor can compensate the hand tremor with a feedback loop control. The manual engaging of tool tip in previous SMART system is replaced by electrical engaging using a squiggle motor. Compared with previous study, this study showed better performance in the hand tremor reduction. From the result, the SMART with automatic engaging may become increasingly valuable in microsurgical instruments.

New endoscopic "scissors" to treat Zenker's diverticulum (with video).

PubMed

Ramchandani, Mohan; Nageshwar Reddy, D

2013-10-01

Zenker's diverticulum (ZD) is a rare disorder but is associated with significant morbidity. Cricopharyngeal (CP) myotomy is the mainstay of treatment, and various flexible endoscopic techniques have been used for division of the septum. However, there is a constant need for improvement in accessories. To evaluate the safety and effectiveness of a new electrocautery endoscopic scissor for CP myotomy in patients with symptomatic ZD. Observational human study. Tertiary-care hospital. This study involved 3 patients with symptomatic ZD. Flexible endoscopic CP myotomy was performed by using a novel scissors-type grasping device. CP myotomy involved 4 steps: (1) opening of the forceps, (2) grasping the muscle fiber, (3) closure of the forceps with application of gentle traction, and (4) dissection of muscle fibers by using cutting current. Intraprocedural bleeding was controlled with the same instrument by grasping vessels and applying coagulation current. Overall feasibility and performance, procedure time to achieve complete CP myotomy. CP myotomy was successfully performed in all patients. Mean procedure time was 10.6 minutes. There were no major adverse events. Minor intraprocedure bleeding occurred in 1 patient. Single arm, limited number of patients. The new instrument has potential advantages in comparison with standard instruments used for CP myotomy. The advantages of this new technique are better control of cutting and hemostatic abilities. Copyright © 2013 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

Optical Field-Strength Polarization of Two-Mode Single-Photon States

ERIC Educational Resources Information Center

Linares, J.; Nistal, M. C.; Barral, D.; Moreno, V.

2010-01-01

We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of…

Searching for primordial magnetic fields with CMB B-modes

NASA Astrophysics Data System (ADS)

Pogosian, Levon; Zucca, Alex

2018-06-01

Was the primordial universe magnetized? The answer to this question would help explain the origin of micro-Gauss strength magnetic fields observed in galaxies. It is also of fundamental importance in developing a complete theory of the early universe. While there can be other signatures of cosmological magnetic fields, a signature in the cosmic microwave background (CMB) would prove their primordial origin. The B-mode polarization of CMB is particularly promising in this regard because there are relatively few other sources of B-modes, and because the vortical modes sourced by the primordial magnetic field (PMF) survive diffusion damping up to a small fraction of the Silk length. At present, the Planck temperature and polarization spectra combined with the B-mode spectrum measured by the South Pole Telescope (SPT) constrain the PMF strength to be no more than  ∼1 nano-Gauss (nG). Because of the quartic scaling of the CMB anisotropy spectra with the PMF strength, this bound will not change by much even with the significantly better measurements of the B-mode spectrum by the Stage III and Stage IV CMB experiments. On the other hand, tightening the bound well below the 1 nG threshold would rule out the purely primordial origin (requiring no dynamo action) of galactic fields. Considering Faraday rotation, which converts some of the E-modes into B-modes and scales linearly with the field strength, will help to achieve this goal. As we demonstrate, the upcoming experiments, such as SPT-3G and the Simons Observatory, will be sensitive to fields of  ∼0.5 nG strength thanks to the mode-coupling signature induced by Faraday rotation. A future Stage IV ground based experiment or a space probe will be capable of probing fields below 0.1 nG, and would detect a scale-invariant PMF of 0.2 nG strength without de-lensing or subtracting the galactic rotation measure.

21 CFR 888.4540 - Orthopedic manual surgical instrument.

Code of Federal Regulations, 2012 CFR

2012-04-01

..., femoral neck punch, socket pusher, reamer, rongeur, scissors, screwdriver, bone skid, staple driver, bone screw starter, surgical stripper, tamp, bone tap, trephine, wire twister, and wrench. (b) Classification...

21 CFR 888.4540 - Orthopedic manual surgical instrument.

Code of Federal Regulations, 2010 CFR

2010-04-01

..., femoral neck punch, socket pusher, reamer, rongeur, scissors, screwdriver, bone skid, staple driver, bone screw starter, surgical stripper, tamp, bone tap, trephine, wire twister, and wrench. (b) Classification...

21 CFR 888.4540 - Orthopedic manual surgical instrument.

Code of Federal Regulations, 2013 CFR

2013-04-01

..., femoral neck punch, socket pusher, reamer, rongeur, scissors, screwdriver, bone skid, staple driver, bone screw starter, surgical stripper, tamp, bone tap, trephine, wire twister, and wrench. (b) Classification...

21 CFR 888.4540 - Orthopedic manual surgical instrument.

Code of Federal Regulations, 2011 CFR

2011-04-01

..., femoral neck punch, socket pusher, reamer, rongeur, scissors, screwdriver, bone skid, staple driver, bone screw starter, surgical stripper, tamp, bone tap, trephine, wire twister, and wrench. (b) Classification...

21 CFR 888.4540 - Orthopedic manual surgical instrument.

Code of Federal Regulations, 2014 CFR

2014-04-01

..., femoral neck punch, socket pusher, reamer, rongeur, scissors, screwdriver, bone skid, staple driver, bone screw starter, surgical stripper, tamp, bone tap, trephine, wire twister, and wrench. (b) Classification...

Forced oral opening for cadavers with rigor mortis: two approaches for the myotomy on the temporal muscles.

PubMed

Nakayama, Y; Aoki, Y; Niitsu, H; Saigusa, K

2001-04-15

Forensic dentistry plays an essential role in personal identification procedures. An adequate interincisal space of cadavers with rigor mortis is required to obtain detailed dental findings. We have developed intraoral and two directional approaches, for myotomy of the temporal muscles. The intraoral approach, in which the temporalis was dissected with scissors inserted via an intraoral incision, was adopted for elderly cadavers, females and emaciated or exhausted bodies, and had a merit of no incision on the face. The two directional approach, in which myotomy was performed with thread-wire saw from behind and with scissors via the intraoral incision, was designed for male muscular youths. Both approaches were effective to obtain a desired degree of an interincisal opening without facial damage.

Improving a scissor-action couch for conformal arc radiotherapy and radiosurgery.

PubMed

Li, Kaile; Yu, Cedric X; Ma, Lijun

2004-01-01

We have developed a method to improve the setup accuracy of a Varian Clinac 6/100 couch for delivering conformal arc therapy using a tertiary micro multileaf collimator (MLC) system. Several immobilization devices have been developed to improve the mechanical stability and isocenter alignment of the couch: turn-knob harnesses, double-track alignment plates, and a drop-in rod that attaches the couch to the concrete floor. These add-on components minimize the intercomponent motion of the couch's scissor elevator, which allows consistent treatment setup. The accuracy of our isocenter couch alignment is an improvement over the above devices, within 1 mm of their accuracy. The couch has been used with over 15 patients and with over 50 modulated conformal arc treatment deliveries at our institution.

Influence of different etching modes on bond strength and fatigue strength to dentin using universal adhesive systems.

PubMed

Takamizawa, Toshiki; Barkmeier, Wayne W; Tsujimoto, Akimasa; Berry, Thomas P; Watanabe, Hedehiko; Erickson, Robert L; Latta, Mark A; Miyazaki, Masashi

2016-02-01

The purpose of this study was to determine the dentin bonding ability of three new universal adhesive systems under different etching modes using fatigue testing. Prime & Bond elect [PE] (DENTSPLY Caulk), Scotchbond Universal [SU] (3M ESPE), and All Bond Universal [AU] (Bisco) were used in this study. A conventional single-step self-etch adhesive, Clearfil Bond SE ONE [CS] (Kuraray Noritake Dental) was also included as a control. Shear bond strengths (SBS) and shear fatigue strength (SFS) to human dentin were obtained in the total-etch mode and self-etch modes. For each test condition, 15 specimens were prepared for the SBS and 30 specimens for SFS. SEM was used to examine representative de-bonded specimens, treated dentin surfaces and the resin/dentin interface for each test condition. Among the universal adhesives, PE in total-etch mode showed significantly higher SBS and SFS values than in self-etch mode. SU and AU did not show any significant difference in SBS and SFS between the total-etch mode and self-etch mode. However, the single-step self-etch adhesive CS showed significantly lower SBS and SFS values in the etch-and-rinse mode when compared to the self-etch mode. Examining the ratio of SFS/SBS, for PE and AU, the etch-and-rinse mode groups showed higher ratios than the self-etch mode groups. The influence of different etching modes on dentin bond quality of universal adhesives was dependent on the adhesive material. However, for the universal adhesives, using the total-etch mode did not have a negative impact on dentin bond quality. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Local vibrational modes of the water dimer - Comparison of theory and experiment

NASA Astrophysics Data System (ADS)

Kalescky, R.; Zou, W.; Kraka, E.; Cremer, D.

2012-12-01

Local and normal vibrational modes of the water dimer are calculated at the CCSD(T)/CBS level of theory. The local H-bond stretching frequency is 528 cm-1 compared to a normal mode stretching frequency of just 143 cm-1. The adiabatic connection scheme between local and normal vibrational modes reveals that the lowering is due to mass coupling, a change in the anharmonicity, and coupling with the local HOH bending modes. The local mode stretching force constant is related to the strength of the H-bond whereas the normal mode stretching force constant and frequency lead to an erroneous underestimation of the H-bond strength.

Cuts and puncture wounds

MedlinePlus

... pointed object such as a nail, knife, or sharp tooth. Symptoms Symptoms include: Bleeding Problems with function ... the last 10 years. Prevention Keep knives, scissors, sharp objects, firearms, and fragile items out of the ...

Effect of 830 nm Diode Laser Irradiation of Root Canal on Bond Strength of Metal and Fiber Post.

PubMed

Strefezza, Claudia; Amaral, Marcello Magri; Quinto, José; Gouw-Soares, Sheila Cynthia; Zamataro, Claudia Bianchi; Zezell, Denise Maria

2018-05-16

The correct selections of the cementing agent, the endodontic post material and placement protocol are critical to provide an increased longevity of the teeth that went through endodontic treatment. The irradiation with diode laser before post cementation, can promote an antimicrobial effect. However, there is a lack of information about the effect of 830 nm diode laser on the post bond strength. This study analyzed the effect of dentin root canal irradiation with high-intensity diode laser, at 830 nm, operating in continuous or pulsed mode, on the retention of metal or fiber posts, cemented with self-etching resinous composite (Panavia F) and zinc phosphate cement (ZnPO 4 ). Human roots were irradiated with diode laser (continuous and pulsed mode). The fiber posts were luted with Panavia F and the metal posts with Panavia F or ZnPO 4 cement. Specimens were sectioned into three sections (cervical, middle, and apical). The bond strength was measured by a push-out mechanical analysis. For the statistical analysis, a three-way ANOVA test was applied following a Tukey's pairwise comparison with a significance level of p = 0.05. The irradiated groups presented higher bond strength compared with nonirradiated group (p < 0.05), and the cervical and middle thirds presented higher on bond strength than the apical. The association of metal post and Panavia F presented higher bond strength when irradiated on continuous mode (p < 0.05). Fiber post and Panavia F presented higher bond strength associated to pulsed mode. The mode seems not to make a significant difference. These results corroborate the importance of the post bond to dentin and root canal debris removal to increase the tooth longevity. It was shown that the dentin to post bond strength were enhanced by the diode laser irradiation either on continuous or pulsed modes.

The dual exo/endo-type mode and the effect of ionic strength on the mode of catalysis of chitinase 60 (CHI60) from Serratia sp. TU09 and its mutants.

PubMed

Kuttiyawong, K; Nakapong, S; Pichyangkura, R

2008-11-03

Mutations of the tryptophan residues in the tryptophan-track of the N-terminal domain (W33F/Y and W69F/Y) and in the catalytic domain (W245F/Y) of Serratia sp. TU09 Chitinase 60 (CHI60) were constructed, as single and double point substitutions to either phenylalanine or tyrosine. The enzyme-substrate interaction and mode of catalysis, exo/endo-type, of wild type CHI60 and mutant enzymes on soluble (partially N-acetylated chitin), amorphous (colloidal chitin), and crystalline (β-chitin) substrates were studied. All CHI60 mutants exhibited a reduced substrate binding activity on colloidal chitin. CHI60 possesses a dual mode of catalysis with both exo- and endo-type activities allowing the enzyme to work efficiently on various substrate types. CHI60 preferentially uses the endo-type mode on soluble and amorphous substrates and the exo-type mode on crystalline substrate. However, the prevalent mode of hydrolysis mediated by CHI60 is regulated by ionic strength. Slightly elevated ionic strength, 0.1-0.2M NaCl, which promotes enzyme-substrate interactions, enhances CHI60 hydrolytic activity on amorphous substrate and, interestingly, on partially N-acetylated chitin. High ionic strength, 0.5-2.0M NaCl, prevents the enzyme from dissociating from amorphous substrate, occupying the enzyme in an enzyme-substrate non-productive complex. However, on crystalline substrates, the activity of CHI60 was only inhibited approximately 50% at high ionic strength, suggesting that the enzyme hydrolyzes crystalline substrates with an exo-type mode processively while remaining tightly bound to the substrate. Moreover, substitution of Trp-33 to either phenylalanine or tyrosine reduced the activity of the enzyme at high ionic strength, suggesting an important role of Trp-33 on enzyme processivity.

Heat resistance study of basalt fiber material via mechanical tests

NASA Astrophysics Data System (ADS)

Gao, Y. Q.; Jia, C.; Meng, L.; Li, X. H.

2017-12-01

This paper focuses on the study of the relationship between the fracture strength of basalt rovings and temperature. Strong stretching performance of the rovings has been tested after the treatment at fixed temperatures but different heating time and then the fracture strength of the rovings exposed to the heating at different temperatures and cooled in different modes investigated. Finally, the fracture strength of the basalt material after the heat treatment was studied. The results showed that the room-temperature strength tends to decrease with an increase of the heat treatment time at 250 °C, but it has the local maximum after 2h heating. And the basalt rovings strength increased after the heat treatment up to 200 °C. It was 16.7 percent higher than the original strength. The strength depends not only on the temperature and duration of the heating, but also on the cooling mode. The value of the strength measured after cold water cooling was less by 6.3% compared with an ambient air cooling mode. The room-temperature breaking strength of the rovings heated at 200 °C and 100 °C for 2 hours each increased by about 14.6% with respect to unpretreated basalt rovings.

Virts on MDDK

NASA Image and Video Library

2010-02-15

S130-E-008276 (15 Feb. 2010) --- NASA astronaut Terry Virts, STS-130 pilot, is pictured near food packages and scissors floating freely on the middeck of space shuttle Endeavour while docked with the International Space Station.

Cycle frequency in standard Rock-Paper-Scissors games: Evidence from experimental economics

NASA Astrophysics Data System (ADS)

Xu, Bin; Zhou, Hai-Jun; Wang, Zhijian

2013-10-01

The Rock-Paper-Scissors (RPS) game is a widely used model system in game theory. Evolutionary game theory predicts the existence of persistent cycles in the evolutionary trajectories of the RPS game, but experimental evidence has remained to be rather weak. In this work, we performed laboratory experiments on the RPS game and analyzed the social-state evolutionary trajectories of twelve populations of N=6 players. We found strong evidence supporting the existence of persistent cycles. The mean cycling frequency was measured to be 0.029±0.009 period per experimental round. Our experimental observations can be quantitatively explained by a simple non-equilibrium model, namely the discrete-time logit dynamical process with a noise parameter. Our work therefore favors the evolutionary game theory over the classical game theory for describing the dynamical behavior of the RPS game.

Apex predator and the cyclic competition in a rock-paper-scissors game of three species

NASA Astrophysics Data System (ADS)

Souza-Filho, C. A.; Bazeia, D.; Ramos, J. G. G. S.

2017-06-01

This work deals with the effects of an apex predator on the cyclic competition among three distinct species that follow the rules of the rock-paper-scissors game. The investigation develops standard stochastic simulations but is motivated by a procedure which is explained in the work. We add the apex predator as the fourth species in a system that contains three species that evolve following the standard rules of migration, reproduction, and predation, and study how the system evolves in this new environment, in comparison with the case in the absence of the apex predator. The results show that the apex predator engenders the tendency to spread uniformly in the lattice, contributing to destroy the spiral patterns, keeping biodiversity but diminishing the average size of the clusters of the species that compete cyclically.

Comparison of micro push-out bond strengths of two fiber posts luted using simplified adhesive approaches.

PubMed

Mumcu, Emre; Erdemir, Ugur; Topcu, Fulya Toksoy

2010-05-01

By means of a micro push-out test, this study compared the bond strengths of two types of fiber-reinforced posts cemented with luting cements based on two currently available adhesive approaches as well as evaluated their failure modes. Sixty extracted single-rooted human maxillary central incisor and canine teeth were sectioned below the cementoenamel junction, and the roots were endodontically treated. Following standardized post space preparation, the roots were divided into two fiber post groups and then further into three subgroups of 10 specimens each according to the luting cements. A push-out test was performed to measure regional bond strengths, and the fracture modes were evaluated using a stereomicroscope. At the root section, there were no statistically significant differences (p>0.05) in push-out bond strength among the tested luting cements. Nevertheless, the push-out bond strength values of glass fiber-reinforced posts were higher than those of carbon fiber-reinforced posts, irrespective of the adhesive approach used. On failure mode, the predominant failure mode was adhesive failure between dentin and the luting cement.

Improving the fracture toughness and the strength of epoxy using nanomaterials--a review of the current status.

PubMed

Domun, N; Hadavinia, H; Zhang, T; Sainsbury, T; Liaghat, G H; Vahid, S

2015-06-21

The incorporation of nanomaterials in the polymer matrix is considered to be a highly effective technique to improve the mechanical properties of resins. In this paper the effects of the addition of different nanoparticles such as single-walled CNT (SWCNT), double-walled CNT (DWCNT), multi-walled CNT (MWCNT), graphene, nanoclay and nanosilica on fracture toughness, strength and stiffness of the epoxy matrix have been reviewed. The Young's modulus (E), ultimate tensile strength (UTS), mode I (GIC) and mode II (GIIC) fracture toughness of the various nanocomposites at different nanoparticle loadings are compared. The review shows that, depending on the type of nanoparticles, the integration of the nanoparticles has a substantial effect on mode I and mode II fracture toughness, strength and stiffness. The critical factors such as maintaining a homogeneous dispersion and good adhesion between the matrix and the nanoparticles are highlighted. The effect of surface functionalization, its relevancy and toughening mechanism are also scrutinized and discussed. A large variety of data comprised of the mechanical properties of nanomaterial toughened composites reported to date has thus been compiled to facilitate the evolution of this emerging field, and the results are presented in maps showing the effect of nanoparticle loading on mode I fracture toughness, stiffness and strength.

Identifying the first folded alkylbenzene via ultraviolet, infrared, and Raman spectroscopy of pentylbenzene through decylbenzene

DOE PAGES

Hewett, Daniel M.; Bocklitz, Sebastian; Tabor, Daniel P.; ...

2017-05-23

The conformational preferences of pentyl- through decylbenzene are studied under jet-cooled conditions in the gas phase. Laser-induced fluorescence excitation spectra, fluorescence-dip infrared spectra in the alkyl CH stretch region, and Raman spectra are combined to provide assignments for the observed conformers. Density functional theory calculations at the B3LYP-D3BJ/def2TZVP level of theory provide relative energies and normal mode vibrations that serve as inputs for an anharmonic local mode theory introduced in earlier work on alkylbenzenes with n = 2–4. This model explicitly includes anharmonic mixing of the CH stretch modes with the overtones of scissors/bend modes of the CH 2 andmore » CH 3 groups in the alkyl chain, and is used to assign and interpret the single-conformation IR spectra. In octylbenzene, a pair of LIF transitions shifted -92 and -78 cm -1 from the all-trans electronic origin have unique alkyl CH stretch transitions that are fit by the local model to a g1g3g4 conformation in which the alkyl chain folds back over the aromatic ring π cloud. Its calculated energy is only 1.0 kJ mol -1 above the all-trans global minimum. This fold is at an alkyl chain length less than half that of the pure alkanes (n = 18), consistent with a smaller energy cost for the g1 dihedral and the increased dispersive interaction of the chain with the π cloud. Local site frequencies for the entire set of conformers from the local mode model show ‘edge effects’ that raise the site frequencies of CH 2(1) and CH 2(2) due to the phenyl ring and CH 2(n - 1) due to the methyl group. The g1g3g4 conformer also shows local sites shifted up in frequency at CH 2(3) and CH 2(6) due to interaction with the π cloud.« less

Analytical solution and applications of three qubits in three coupled modes without rotating wave approximation

NASA Astrophysics Data System (ADS)

Zhang, Jian-Song; Zhang, Liu-Juan; Chen, Ai-Xi; Abdel-Aty, Mahmoud

2018-06-01

We study the dynamics of the three-qubit system interacting with multi-mode without rotating wave approximation (RWA). A physical realization of the system without direct qubits interactions with dephasing bath is proposed. It is shown that non-Markovian characters of the purity of the three qubits and the coupling strength of modes are stronger enough the RWA is no longer valid. The influences of the dephasing of qubits and interactions of modes on the dynamics of genuine multipartite entanglement and bipartite correlations of qubits are investigated. The multipartite and bipartite quantum correlations could be generated faster if we increase the coupling strength of modes and the RWA is not valid when the coupling strength is strong enough. The unitary transformations approach adopted here can be extended to other systems such as circuit or cavity quantum electrodynamic systems in the strong coupling regime.

[Effect of core: dentin thickness ratio on the flexure strength of IPS Empress II heat-pressed all-ceramic restorative material].

PubMed

Liu, Yi-hong; Feng, Hai-lan; Bao, Yi-wang; Qiu, Yan

2007-02-18

To evaluate the effect of core:dentin thickness ratio on the flexure strength, fracture mode and origin of bilayered IPS Empress II ceramic composite specimens. IPS Empress II core ceramic, dentin porcelain and bilayered composite specimens with core:dentin thickness ratio of 2:1 and 1:1 were tested in three-point flexure strength. Mean strengths and standard deviations were determined. The optical microscopy was employed for identification of the fracture mode and origin. The flexure strength of dentin porcelain was the smallest(62.7 MPa), and the strength of bilayered composite specimens was smaller than single-layered core ceramic(190.2 MPa). The core: dentin ratio did not influence the strength of bilayered composite specimens. The frequency of occurrence of bilayered specimen delaminations was higher in the group of core: dentin thickness ratio of 1:1 than in the group of 2:1. IPS Empress II core ceramic was significantly stronger than veneering dentin porcelain. Core:dentin thickness ratio could significantly influence the fracture mode and origin, and bilayered IPS Empress II ceramic composite specimens showed little influence in the fracture strength.

Strength, Fracture Toughness, Fatigue, and Standardization Issues of Free-standing Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Zhu, Dong-Ming; Miller, Robert A.

2003-01-01

Strength, fracture toughness and fatigue behavior of free-standing thick thermal barrier coatings of plasma-sprayed ZrO2-8wt % Y2O3 were determined at ambient and elevated temperatures in an attempt to establish a database for design. Strength, in conjunction with deformation (stress-strain behavior), was evaluated in tension (uniaxial and trans-thickness), compression, and uniaxial and biaxial flexure; fracture toughness was determined in various load conditions including mode I, mode II, and mixed modes I and II; fatigue or slow crack growth behavior was estimated in cyclic tension and dynamic flexure loading. Effect of sintering was quantified through approaches using strength, fracture toughness, and modulus (constitutive relations) measurements. Standardization issues on test methodology also was presented with a special regard to material's unique constitutive relations.

Robust magnon-photon coupling in a planar-geometry hybrid of inverted split-ring resonator and YIG film.

PubMed

Bhoi, Biswanath; Kim, Bosung; Kim, Junhoe; Cho, Young-Jun; Kim, Sang-Koog

2017-09-20

We experimentally demonstrate strongly enhanced coupling between excited magnons in an Yttrium Iron Garnet (YIG) film and microwave photons in an inverted pattern of split-ring resonator (noted as ISRR). The anti-crossing effects of the ISRR's photon mode and the YIG's magnon modes were found from |S 21 |-versus-frequency measurements for different strengths and directions of externally applied magnetic fields. The spin-number-normalized coupling strength (i.e. single spin-photon coupling) [Formula: see text] was determined to 0.194 Hz ([Formula: see text] = 90 MHz) at 3.7 GHz frequency. Furthermore, we found that additional fine features in the anti-crossing region originate from the excitation of different spin-wave modes (such as the magnetostatic surface and the backward-volume magnetostatic spin-waves) rather than the Kittel-type mode. These spin-wave modes, as coupled with the ISRR mode, modify the anti-crossing effect as well as their coupling strength. An equivalent circuit model very accurately reproduced the observed anti-crossing effect and its coupling strength variation with the magnetic field direction in the planar-geometry ISRR/YIG hybrid system. This work paves the way for the design of new types of high-gain magnon-photon coupling systems in planar geometry.

Local vibrational modes of the formic acid dimer - the strength of the double hydrogen bond

NASA Astrophysics Data System (ADS)

Kalescky, R.; Kraka, E.; Cremer, D.

2013-07-01

The 24 normal and 24 local vibrational modes of the formic acid dimer formed by two trans formic acid monomers to a ring (TT1) are analysed utilising preferentially experimental frequencies, but also CCSD(T)/CBS and ωB97X-D harmonic vibrational frequencies. The local hydrogen bond (HB) stretching frequencies are at 676 cm-1 and by this 482 and 412 cm-1 higher compared to the measured symmetric and asymmetric HB stretching frequencies at 264 and 194 cm-1. The adiabatic connection scheme between local and normal vibrational modes reveals that the lowering is due to the topology of dimer TT1, mass coupling, and avoided crossings involving the HṡṡṡOC bending modes. The HB local mode stretching force constant is related to the strength of the HB whereas the normal mode stretching force constant and frequency lead to an erroneous underestimation of the HB strength. The HB in TT1 is stabilised by electron delocalisation in the O=C-O units fostered by forming a ring via double HBs. This implies that the CO apart from the OH local stretching frequencies reflect the strength of the HB via their red or blue shifts relative to their corresponding values in trans formic acid.

Bonding performance of universal adhesives to er,cr:YSGG laser-irradiated enamel.

PubMed

Ayar, Muhammet Kerim; Erdemir, Fatih

2017-04-01

Universal adhesives have been recently introduced for use as self-etch or etch-and-rinse adhesives depending on the dental substrate and clinical condition. However, their bonding effectiveness to laser-irradiated enamel is still not well-known. Thus, the aim of this study was to compare the shear bond strength (SBS) of universal adhesives (Single Bond Universal; Nova Compo-B Plus) applied to Er,Cr:YSGG laser-irradiated enamel with SBS of the same adhesives applied in self-etch and acid-etching modes, respectively. Crown segments of sixty bovine incisors were embedded into standardized acrylic blocks. Flattened enamel surfaces were prepared. Specimens were divided into six groups according to universal adhesives and application modes randomly (n = 10), as follows: Single Bond Universal/acid-etching mode; Nova Compo-B Plus/acid-etching mode; Single Bond Universal/self-etching mode; Nova Compo-B Plus/self-etching mode; and Single Bond Universal/Er,Cr:YSGG Laser-etching mode; Nova Compo-B Plus/Er,Cr:YSGG Laser-etching mode. After surface treatments, universal adhesives were applied onto surfaces. SBS was determined after storage in water for 24 h using a universal testing machine with a crosshead speed of 0.5 mm min -1 . Failure modes were evaluated using a stereomicroscope. Data was analyzed using two-way of analyses of variances (ANOVA) (p = 0.05). Two-way ANOVA revealed that adhesive had no effect on SBS (p = 0.88), but application mode significantly influenced SBS (p = 0.00). Acid-etching significantly increased SBS, whereas there are no significant differences between self-etch mode and laser-etching for both adhesives. The bond strength of universal adhesives may depend on application mode. Acid etching may significantly increase bond strength, while laser etching may provide similar bond strength when compared to self-etch mode. © 2016 Wiley Periodicals, Inc.

Effects of core-to-dentin thickness ratio on the biaxial flexural strength, reliability, and fracture mode of bilayered materials of zirconia core (Y-TZP) and veneer indirect composite resins.

PubMed

Su, Naichuan; Liao, Yunmao; Zhang, Hai; Yue, Li; Lu, Xiaowen; Shen, Jiefei; Wang, Hang

2017-01-01

Indirect composite resins (ICR) are promising alternatives as veneering materials for zirconia frameworks. The effects of core-to-dentin thickness ratio (C/Dtr) on the mechanical property of bilayered veneer ICR/yttria-tetragonal zirconia polycrystalline (Y-TZP) core disks have not been previously studied. The purpose of this in vitro study was to assess the effects of C/Dtr on the biaxial flexural strength, reliability, and fracture mode of bilayered veneer ICR/ Y-TZP core disks. A total of 180 bilayered 0.6-mm-thick composite resin disks in core material and C/Dtr of 2:1, 1:1, and 1:2 were tested with either core material placed up or placed down for piston-on-3-ball biaxial flexural strength. The mean biaxial flexural strength, Weibull modulus, and fracture mode were measured to evaluate the variation trend of the biaxial flexural strength, reliability, and fracture mode of the bilayered disks with various C/Dtr. One-way analysis of variance (ANOVA) and chi-square tests were used to evaluate the variation tendency of fracture mode with the C/Dtr or material placed down during testing (α=.05). Light microscopy was used to identify the fracture mode. The mean biaxial flexural strength and reliability improved with the increase in C/Dtr when specimens were tested with the core material either up and down, and depended on the materials that were placed down during testing. The rates of delamination, Hertzian cone cracks, subcritical radial cracks, and number of fracture fragments partially depended on the C/Dtr and the materials that were placed down during testing. The biaxial flexural strength, reliability, and fracture mode in bilayered structures of Y-TZP core and veneer ICR depend on both the C/Dtr and the material that was placed down during testing. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Influence of application method on surface free-energy and bond strength of universal adhesive systems to enamel.

PubMed

Imai, Arisa; Takamizawa, Toshiki; Sai, Keiichi; Tsujimoto, Akimasa; Nojiri, Kie; Endo, Hajime; Barkmeier, Wayne W; Latta, Mark A; Miyazaki, Masashi

2017-10-01

The aim of the present study was to determine the influence of different adhesive application methods and etching modes on enamel bond effectiveness of universal adhesives using shear bond strength (SBS) testing and surface free-energy (SFE) measurements. The adhesives Scotchbond Universal, All-Bond Universal, Adhese Universal, and G-Premio Bond were used. Prepared bovine enamel specimens were divided into four groups, based on type of adhesive, and subjected to the following surface treatments: (i) total-etch mode with active application; (ii) total-etch mode with inactive application; (iii) self-etch mode with active application; and (iv) self-etch mode with inactive application. Bonded specimens were subjected to SBS testing. The SFE of the enamel surfaces with adhesive was measured after rinsing with acetone and water. The SBS values in total-etch mode were significantly higher than those in self-etch mode. In total-etch mode, significantly lower SBS values were observed with active application compared with inactive application; in contrast, in self-etch mode there were no significant differences in SBS between active and inactive applications. A reduction in total SFE was observed for active application compared with inactive application. The interaction between etching mode and application method was statistically significant, and the application method significantly affected enamel bond strength in total-etch mode. © 2017 Eur J Oral Sci.

Degree of conversion and bond strength of resin-cements to feldspathic ceramic using different curing modes.

PubMed

Novais, Veridiana Resende; Raposo, Luís Henrique Araújo; Miranda, Rafael Resende de; Lopes, Camila de Carvalho Almança; Simamoto, Paulo Cézar; Soares, Carlos José

2017-01-01

The aim of this study was to assess the performance of resin cements when different curing modes are used, by evaluating the degree of conversion and bond strength to a ceramic substrate. Three resin cements were evaluated, two dual-cured (Variolink II and RelyX ARC) and one light-cured (Variolink Veneer). The dual-cured resin cements were tested by using the dual activation mode (base and catalyst) and light-activation mode (base paste only). For degree of conversion (DC) (n=5), a 1.0 mm thick feldspathic ceramic disc was placed over the resin cement specimens and the set was light activated with a QTH unit. After 24 h storage, the DC was measured with Fourier transform infrared spectroscopy (FTIR). For microshear bond strength testing, five feldspathic ceramic discs were submitted to surface treatment, and three cylindrical resin cement specimens were bonded to each ceramic surface according to the experimental groups. After 24 h, microshear bond testing was performed at 0.5 mm/min crosshead speed until the failure. Data were submitted to one-way ANOVA followed by Tukey test (p<0.05). Scanning electron microscopy (SEM) was used for classifying the failure modes. Higher DC and bond strength values were shown by the resin cements cured by using the dual activation mode. The Variolink II group presented higher DC and bond strength values when using light-activation only when compared with the Variolink Veneer group. The base paste of dual-cured resin cements in light-activation mode can be used for bonding translucent ceramic restorations of up to or less than 1.0 mm thick.

Food packages for use on the Gemini 4 flight

NASA Technical Reports Server (NTRS)

1965-01-01

Food packages for use on the Gemini 4 flight. Packages include beef and gravy, peaches, strawberry cereal cubes and beef sandwiches. Water gun is used to reconstitute dehydrated food. Scissors are used to open the packages.

Heterogeneous network promotes species coexistence: metapopulation model for rock-paper-scissors game.

PubMed

Nagatani, Takashi; Ichinose, Genki; Tainaka, Kei-Ichi

2018-05-04

Understanding mechanisms of biodiversity has been a central question in ecology. The coexistence of three species in rock-paper-scissors (RPS) systems are discussed by many authors; however, the relation between coexistence and network structure is rarely discussed. Here we present a metapopulation model for RPS game. The total population is assumed to consist of three subpopulations (nodes). Each individual migrates by random walk; the destination of migration is randomly determined. From reaction-migration equations, we obtain the population dynamics. It is found that the dynamic highly depends on network structures. When a network is homogeneous, the dynamics are neutrally stable: each node has a periodic solution, and the oscillations synchronize in all nodes. However, when a network is heterogeneous, the dynamics approach stable focus and all nodes reach equilibriums with different densities. Hence, the heterogeneity of the network promotes biodiversity.

A portable fracture toughness tester for biological materials

NASA Astrophysics Data System (ADS)

Darvell, B. W.; Lee, P. K. D.; Yuen, T. D. B.; Lucas, P. W.

1996-06-01

A portable mechanical tester is described which is both lightweight and cheap to produce. The machine is simple and convenient to operate and requires only a minimum of personnel training. It can be used to measure the fundamental mechanical properties of pliant solids, particularly toughness (in the sense of `work of fracture') using either scissors or wedge tests. This is achieved through a novel hardware integration technique. The circuits are described. The use of the machine does not require a chart recorder but it can be linked to a personal computer, either to show force - displacement relationships or for data storage. The design allows the use of any relatively `soft' mechanical test, i.e. tests in which the deformability of the frame of the machine and its load cell do not introduce significant errors into the results. Examples of its use in measuring the toughness of biomaterials by scissors (paper, wood) and wedges (mung bean starch gels) are given.

Mining machine with adjustable jib

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

Hart, D.

1987-05-26

A mining machine is described having a pair of crawler tracks, a means for individually driving each of the crawler tracks, a frame mounted on the crawler tracks, an elongated jib carrying a sprocket at each end, an endless cutting chain supported on the sprockets, cutters and loading flights mounted on the endless cutting chain, and means on the frame supporting the elongated jib. The means support the elongated jib consisting of a bridge on the frame, at least one scissors linkage pivotally mounted on the bridge, and arm having a first end attached to the scissors linkage, a frontmore » plate mounted on the second end of the arm and means adjustably mounting the elongated jib on the front plate. The means adjustably mount the elongated jib on the front plate including a first means for rotating the elongated jib between a vertical position and a horizontal position.« less

Spatial pattern dynamics due to the fitness gradient flux in evolutionary games.

PubMed

deForest, Russ; Belmonte, Andrew

2013-06-01

We introduce a nondiffusive spatial coupling term into the replicator equation of evolutionary game theory. The spatial flux is based on motion due to local gradients in the relative fitness of each strategy, providing a game-dependent alternative to diffusive coupling. We study numerically the development of patterns in one dimension (1D) for two-strategy games including the coordination game and the prisoner's dilemma, and in two dimensions (2D) for the rock-paper-scissors game. In 1D we observe modified traveling wave solutions in the presence of diffusion, and asymptotic attracting states under a frozen-strategy assumption without diffusion. In 2D we observe spiral formation and breakup in the frozen-strategy rock-paper-scissors game without diffusion. A change of variables appropriate to replicator dynamics is shown to correctly capture the 1D asymptotic steady state via a nonlinear diffusion equation.

Limit cycles and the benefits of a short memory in rock-paper-scissors games.

PubMed

Burridge, James

2015-10-01

When playing games in groups, it is an advantage for individuals to have accurate statistical information on the strategies of their opponents. Such information may be obtained by remembering previous interactions. We consider a rock-paper-scissors game in which agents are able to recall their last m interactions, used to estimate the behavior of their opponents. At critical memory length, a Hopf bifurcation leads to the formation of stable limit cycles. In a mixed population, agents with longer memories have an advantage, provided the system has a stable fixed point, and there is some asymmetry in the payoffs of the pure strategies. However, at a critical concentration of long memory agents, the appearance of limit cycles destroys their advantage. By introducing population dynamics that favors successful agents, we show that the system evolves toward the bifurcation point.

Limit cycles and the benefits of a short memory in rock-paper-scissors games

NASA Astrophysics Data System (ADS)

Burridge, James

2015-10-01

When playing games in groups, it is an advantage for individuals to have accurate statistical information on the strategies of their opponents. Such information may be obtained by remembering previous interactions. We consider a rock-paper-scissors game in which agents are able to recall their last m interactions, used to estimate the behavior of their opponents. At critical memory length, a Hopf bifurcation leads to the formation of stable limit cycles. In a mixed population, agents with longer memories have an advantage, provided the system has a stable fixed point, and there is some asymmetry in the payoffs of the pure strategies. However, at a critical concentration of long memory agents, the appearance of limit cycles destroys their advantage. By introducing population dynamics that favors successful agents, we show that the system evolves toward the bifurcation point.

Correction of a mutilated dentition with mini-implants as anchorage.

PubMed

Hyun, Jae-Man; Kim, Tae-Woo

2010-11-01

The patient was an adolescent boy, aged 15.6 years, with a mutilated dentition. He had extrusion of the maxillary left first molar because of loss of the mandibular first molar and lingual tilting and rotation of the mandibular second molars. Both left and right second molars were in scissors-bite that was more severe on the left side. By using mini-implants and a TPA with hooks, a 3-mm intrusion was successfully made on the maxillary left first molar. This provided room for mesial movement of the mandibular left second molar. The second molar was protracted into the space of the missing first molar, and the mandibular left third molar was positioned in place of the second molar. The second molars scissors-bite was corrected. Active treatment took 45 months, and the treatment result remained stable 2 years after debonding. Copyright © 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Spatial pattern dynamics due to the fitness gradient flux in evolutionary games

NASA Astrophysics Data System (ADS)

deForest, Russ; Belmonte, Andrew

2013-06-01

We introduce a nondiffusive spatial coupling term into the replicator equation of evolutionary game theory. The spatial flux is based on motion due to local gradients in the relative fitness of each strategy, providing a game-dependent alternative to diffusive coupling. We study numerically the development of patterns in one dimension (1D) for two-strategy games including the coordination game and the prisoner's dilemma, and in two dimensions (2D) for the rock-paper-scissors game. In 1D we observe modified traveling wave solutions in the presence of diffusion, and asymptotic attracting states under a frozen-strategy assumption without diffusion. In 2D we observe spiral formation and breakup in the frozen-strategy rock-paper-scissors game without diffusion. A change of variables appropriate to replicator dynamics is shown to correctly capture the 1D asymptotic steady state via a nonlinear diffusion equation.

Hamming distance and mobility behavior in generalized rock-paper-scissors models

NASA Astrophysics Data System (ADS)

Bazeia, D.; Menezes, J.; de Oliveira, B. F.; Ramos, J. G. G. S.

2017-09-01

This work reports on two related investigations of stochastic simulations which are widely used to study biodiversity and other related issues. We first deal with the behavior of the Hamming distance under the increase of the number of species and the size of the lattice, and then investigate how the mobility of the species contributes to jeopardize biodiversity. The investigations are based on the standard rules of reproduction, mobility and predation or competition, which are described by specific rules, guided by generalization of the rock-paper-scissors game, valid in the case of three species. The results on the Hamming distance indicate that it engenders universal behavior, independently of the number of species and the size of the square lattice. The results on the mobility confirm the prediction that it may destroy diversity, if it is increased to higher and higher values.

Experimental Investigation on the Joining of Aluminum Alloy Sheets Using Improved Clinching Process.

PubMed

Chen, Chao; Zhao, Shengdun; Han, Xiaolan; Zhao, Xuzhe; Ishida, Tohru

2017-08-01

Aluminum alloy sheets have been widely used to build the thin-walled structures by mechanical clinching technology in recent years. However, there is an exterior protrusion located on the lower sheet and a pit on the upper sheet, which may restrict the application of the clinching technology in visible areas. In the present study, an improved clinched joint used to join aluminum alloy sheets was investigated by experimental method. The improved clinching process used for joining aluminum alloy evolves through four phases: (a) localized deformation; (b) drawing; (c) backward extrusion; and (d) mechanical interlock forming. A flat surface can be produced using the improved clinching process. Shearing strength, tensile strength, material flow, main geometrical parameters, and failure mode of the improved clinched joint were investigated. The sheet material was compressed to flow radially and upward using a punch, which generated a mechanical interlock by producing severe localized plastic deformation. The neck thickness and interlock of the improved clinched joint were increased by increasing the forming force, which also contributed to increase the strength of the clinched joint. The improved clinched joint can get high shearing strength and tensile strength. Three main failure modes were observed in the failure process, which were neck fracture mode, button separation mode, and mixed failure mode. The improved clinched joint has better joining quality to join aluminum alloy sheets on the thin-walled structures.

Experimental Investigation on the Joining of Aluminum Alloy Sheets Using Improved Clinching Process

PubMed Central

Chen, Chao; Zhao, Shengdun; Han, Xiaolan; Zhao, Xuzhe; Ishida, Tohru

2017-01-01

Aluminum alloy sheets have been widely used to build the thin-walled structures by mechanical clinching technology in recent years. However, there is an exterior protrusion located on the lower sheet and a pit on the upper sheet, which may restrict the application of the clinching technology in visible areas. In the present study, an improved clinched joint used to join aluminum alloy sheets was investigated by experimental method. The improved clinching process used for joining aluminum alloy evolves through four phases: (a) localized deformation; (b) drawing; (c) backward extrusion; and (d) mechanical interlock forming. A flat surface can be produced using the improved clinching process. Shearing strength, tensile strength, material flow, main geometrical parameters, and failure mode of the improved clinched joint were investigated. The sheet material was compressed to flow radially and upward using a punch, which generated a mechanical interlock by producing severe localized plastic deformation. The neck thickness and interlock of the improved clinched joint were increased by increasing the forming force, which also contributed to increase the strength of the clinched joint. The improved clinched joint can get high shearing strength and tensile strength. Three main failure modes were observed in the failure process, which were neck fracture mode, button separation mode, and mixed failure mode. The improved clinched joint has better joining quality to join aluminum alloy sheets on the thin-walled structures. PMID:28763027

Food mechanical properties and dietary ecology.

PubMed

Berthaume, Michael A

2016-01-01

Interdisciplinary research has benefitted the fields of anthropology and engineering for decades: a classic example being the application of material science to the field of feeding biomechanics. However, after decades of research, discordances have developed in how mechanical properties are defined, measured, calculated, and used due to disharmonies between and within fields. This is highlighted by "toughness," or energy release rate, the comparison of incomparable tests (i.e., the scissors and wedge tests), and the comparison of incomparable metrics (i.e., the stress and displacement-limited indices). Furthermore, while material scientists report on a myriad of mechanical properties, it is common for feeding biomechanics studies to report on just one (energy release rate) or two (energy release rate and Young's modulus), which may or may not be the most appropriate for understanding feeding mechanics. Here, I review portions of materials science important to feeding biomechanists, discussing some of the basic assumptions, tests, and measurements. Next, I provide an overview of what is mechanically important during feeding, and discuss the application of mechanical property tests to feeding biomechanics. I also explain how 1) toughness measures gathered with the scissors, wedge, razor, and/or punch and die tests on non-linearly elastic brittle materials are not mechanical properties, 2) scissors and wedge tests are not comparable and 3) the stress and displacement-limited indices are not comparable. Finally, I discuss what data gathered thus far can be best used for, and discuss the future of the field, urging researchers to challenge underlying assumptions in currently used methods to gain a better understanding between primate masticatory morphology and diet. © 2016 Wiley Periodicals, Inc.

Small incision iris tumour biopsy using a cavernous sampling forceps.

PubMed

Chronopoulos, Argyrios; Kilic, Ergin; Joussen, Antonia M; Lipski, Andreas

2014-11-01

The aim of this retrospective report is to describe our experience with the Essen-23G biopsy forceps (Akgül forceps) for biopsies of pigmented iris tumours. In this retrospective study of cases between October 2012 and September 2013, patients with iris tumours and clinical signs for malignancy underwent biopsy to secure the diagnosis. The Essen-23G-forceps was used to grasp and extract tissue through a clear corneal incision. Eventual entry and bimanual manipulation with a 23G mini-scissors was achieved through a second incision. Tissue samples were fixed in a sterile tube for further histopathological and immunohistochemical evaluation. Seven eyes of seven patients underwent biopsy using the forceps. The average thickness of the iris tumours was 1.07±0.79 mm. A second corneal incision for scissoring in a bimanual technique was necessary in 5 cases (71%). In 6 cases (85%), a precise histological and immunohistochemical diagnosis was achieved. Complications were limited to minute bleeding at the biopsy site and one case of relative pupil enlargement (anisocoria) without further refractive issues. Iris tumour biopsies can be successfully approached using a cavernous 23G intraocular forceps with a low risk for procedure-related complications. The conical interior design allows for removal of whole tissue pieces with minimal manipulative artefacts. An optional bimanual access through a second corneal incision and use of a 23G scissors provides better efficacy. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Effect of Interfacial Microstructures on the Bonding Strength of Sn-3.0Ag-0.5Cu Pb-Free Solder Bump

NASA Astrophysics Data System (ADS)

Kim, Jae-Myeong; Jeong, Myeong-Hyeok; Yoo, Sehoon; Park, Young-Bae

2012-05-01

The effect of interfacial microstructures on the bonding strength of Sn-3.0Ag-0.5Cu Pb-free solder bumps with respect to the loading speed, annealing time, and surface finish was investigated. The shear strength increased and the ductility decreased with increasing shear speed, primarily because of the time-independent plastic hardening and time-dependent strain-rate sensitivity of the solder alloy. The shear strength and toughness decreased for all surface finishes under the high-speed shear test of 500 mm/s as a result of increasing intermetallic compound (IMC) growth and pad interface weakness associated with increased annealing time. The immersion Sn and organic solderability preservative (OSP) finishes showed lower shear strength compared to the electroless nickel immersion gold (ENIG) finish. With increasing annealing time, the ENIG finish exhibited the pad open fracture mode, whereas the immersion Sn and OSP finishes exhibited the brittle fracture mode. In addition, the shear strength of the solder joints was correlated with each fracture mode.

EFFECT OF RADIUS OF LOADING NOSE AND SUPPORTS IN SHORT BEAM TEST FIXTURE ON FRACTURE MODE AND INTERLAMINAR SHEAR STRENGTH OF GFRP AT 77 K

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

Nishimura, A.

2008-03-03

A short beam test is useful to evaluate interlaminar shear strength of glass fiber reinforced plastics, especially for material selection. However, effect of test fixture configuration on interlaminar shear strength has not been clarified. This paper describes dependence of fracture mode and interlaminar shear strength on the fixture radius using the same materials and procedure. In addition, global understanding of the role of the fixture is discussed. When small loading nose and supports are used for the tests, bending fracture or translaminar fracture happens and the interlaminar shear strength would become smaller. By adopting the large radius loading nose andmore » supports (6 mm radius is recommended), it is newly recognized that some stress concentration is able to be reduced, and the interlaminar fracture tends to occur and the other fracture modes will be suppressed. The interlaminar shear strength of 2.5 mm thick GFRP plate of G-10CR is evaluated as 130-150 MPa at 77 K.« less

Polygyny, mate-guarding, and posthumous fertilization as alternative male mating strategies.

PubMed

Zamudio, K R; Sinervo, B

2000-12-19

Alternative male mating strategies within populations are thought to be evolutionarily stable because different behaviors allow each male type to successfully gain access to females. Although alternative male strategies are widespread among animals, quantitative evidence for the success of discrete male strategies is available for only a few systems. We use nuclear microsatellites to estimate the paternity rates of three male lizard strategies previously modeled as a rock-paper-scissors game. Each strategy has strengths that allow it to outcompete one morph, and weaknesses that leave it vulnerable to the strategy of another. Blue-throated males mate-guard their females and avoid cuckoldry by yellow-throated "sneaker" males, but mate-guarding is ineffective against aggressive orange-throated neighbors. The ultradominant orange-throated males are highly polygynous and maintain large territories; they overpower blue-throated neighbors and cosire offspring with their females, but are often cuckolded by yellow-throated males. Finally, yellow-throated sneaker males sire offspring via secretive copulations and often share paternity of offspring within a female's clutch. Sneaker males sire more offspring posthumously, indicating that sperm competition may be an important component of their strategy.

78 FR 36239 - Notice of Inventory Completion: Wayne State University Gordon L. Grosscup Museum of Anthropology...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-17

... human remains reportedly included a pair of scissors, a hand blown bottle, a scalpel, six silver... with several pieces of animal bone. No known individuals were identified. No associated funerary...

Erythromycin and Benzoyl Peroxide Topical

MedlinePlus

... on to step 5. If your medication comes in small pouches, use scissors or your fingers to tear off the top at the notched tab. Do not open the pouch with your teeth. Squeeze the contents of the pouch onto your ...

Boson mode, Medium Range Structure and Intermediate Phase (IP) in (Na2O)x(B2O3)1-x glasses

NASA Astrophysics Data System (ADS)

Vignarooban, K.; Boolchand, P.; Micoulaut, M.; Malki, M.

2012-02-01

Raman scattering of titled glasses are examined using a T64000 Dispersive system. Scattering strengths of the Boson mode (40 cm-1, 70 cm-1) and the Boroxyl ring (BR) mode (808 cm-1) are found to decrease with increasing x at the same rate in the 0 < x < 20% soda range. Apparently, the 2D character of BRs embedded in a 3D network gives rise to the Boson mode.ootnotetextM. Flores-Ruiz and G. Naumis, PRB, 2011. 83: p. 184204 The triad of modes (705, 740, 770 cm-1) near the 808 cm-1 mode are found to display a maximum in scattering strength near x = 37% (705 cm-1), 33% (740 cm-1) and 25% (770 cm-1), suggesting that these are also ring modes of Na-tripentaborate (STPB), Na-diborate (SDB) and Na-triborate (STB) super-structures. Variations in Raman scattering strengths also suggest that STB percolate near x = 20%, the stress transition, while the STPB and SDTB percolate near x = 40%, the rigidity transition. These transitions were inferred from m-DSC experiments that show an intermediate phase in the 20% < x < 40% range in dry and homogeneous glasses.

Isospin and Spin-Isospin Modes in Nuclei

NASA Astrophysics Data System (ADS)

Zegers, R. G. T.; van den Berg, A. M.; Brandenburg, S.; Fleurot, F. R. R.; Hannen, V. M.; Harakeh, M. N.; van der Schaaf, K.; van der Werf, S. Y.; Wilschut, H. W.; Guillot, J.; Laurent, H.; Willis, A.; Jänecke, J.; Fujiwara, M.

2002-09-01

The (3He,t) reaction on Pb at E3He=177 MeV and the subsequent decay by proton emission were studied in order to distinguish isovector monopole strength corresponding to 2ħω transitions from the non-resonant continuum background. Monopole strength at excitation energies above 25 MeV was discovered and compared to the calculated strength due to the isovector giant monopole resonance and the spin-flip isovector monopole resonance. Calculations in a normal-modes framework show that all isovector monopole strength can be accounted for if the branching ratio for decay by proton emission is 20%.

Frequency dependence 3.0: an attempt at codifying the evolutionary ecology perspective.

PubMed

Metz, Johan A J; Geritz, Stefan A H

2016-03-01

The fitness concept and perforce the definition of frequency independent fitnesses from population genetics is closely tied to discrete time population models with non-overlapping generations. Evolutionary ecologists generally focus on trait evolution through repeated mutant substitutions in populations with complicated life histories. This goes with using the per capita invasion speed of mutants as their fitness. In this paper we develop a concept of frequency independence that attempts to capture the practical use of the term by ecologists, which although inspired by population genetics rarely fits its strict definition. We propose to call the invasion fitnesses of an eco-evolutionary model frequency independent when the phenotypes can be ranked by competitive strength, measured by who can invade whom. This is equivalent to the absence of weak priority effects, protected dimorphisms and rock-scissor-paper configurations. Our concept differs from that of Heino et al. (TREE 13:367-370, 1998) in that it is based only on the signs of the invasion fitnesses, whereas Heino et al. based their definitions on the structure of the feedback environment, summarising the effect of all direct and indirect interactions between individuals on fitness. As it turns out, according to our new definition an eco-evolutionary model has frequency independent fitnesses if and only if the effect of the feedback environment on the fitness signs can be summarised by a single scalar with monotonic effect. This may be compared with Heino et al.'s concept of trivial frequency dependence defined by the environmental feedback influencing fitness, and not just its sign, in a scalar manner, without any monotonicity restriction. As it turns out, absence of the latter restriction leaves room for rock-scissor-paper configurations. Since in 'realistic' (as opposed to toy) models frequency independence is exceedingly rare, we also define a concept of weak frequency dependence, which can be interpreted intuitively as almost frequency independence, and analyse in which sense and to what extent the restrictions on the potential model outcomes of the frequency independent case stay intact for models with weak frequency dependence.

Effect of various bleaching treatments on shear bond strength of different universal adhesives and application modes

PubMed Central

2018-01-01

Objectives The aim of this in vitro study was to evaluate the bond strength of 2 universal adhesives used in different application modes to bleached enamel. Materials and Methods Extracted 160 sound human incisors were used for the study. Teeth were divided into 4 treatment groups: No treatment, 35% hydrogen peroxide, 16% carbamid peroxide, 7.5% carbamid peroxide. After bleaching treatments, groups were divided into subgroups according to the adhesive systems used and application modes (n = 10): 1) Single Bond Universal, etch and rinse mode; 2) Single Bond Universal, self-etch mode; 3) Gluma Universal, etch and rinse mode; 4) Gluma Universal, self-etch mode. After adhesive procedures nanohybrid composite resin cylinders were bonded to the enamel surfaces. All specimens were subjected to shear bond strength (SBS) test after thermocycling. Data were analyzed using a 3-way analysis of variance (ANOVA) and Tukey post hoc test. Results No significant difference were found among bleaching groups (35% hydrogen peroxide, 16% carbamid peroxide, 7.5% carbamid peroxide, and no treatment groups) in the mean SBS values. There was also no difference in SBS values between Single Bond Universal and Gluma Universal at same application modes, whereas self-etch mode showed significantly lower SBS values than etch and rinse mode (p < 0.05). Conclusions The bonding performance of the universal adhesives was enhanced with the etch and rinse mode application to bleached enamel and non-bleached enamel. PMID:29765900

Mission Specialist (MS) Lenoir cuts Pilot Overmyer's hair on middeck

NASA Technical Reports Server (NTRS)

1982-01-01

Mission Specialist (MS) Lenoir, using hairbrush and scissors, cuts Pilot Overmyer's hair and trims his sideburns in front of forward middeck lockers. Personal hygiene kit (open), towels, and field sequential (FS) crew cabin camera are attached to lockers.

The Hooey Machine.

ERIC Educational Resources Information Center

Scarnati, James T.; Tice, Craig J.

1992-01-01

Describes how students can make and use Hooey Machines to learn how mechanical energy can be transferred from one object to another within a system. The Hooey Machine is made using a pencil, eight thumbtacks, one pushpin, tape, scissors, graph paper, and a plastic lid. (PR)

Wakata haircut in the Service Module (SM)

NASA Image and Video Library

2009-04-04

ISS018-E-044607 (4 April 2009) --- Japan Aerospace Exploration Agency (JAXA) astronaut Koichi Wakata, Expedition 18/19 flight engineer, returns scissors and hair clippers to their storage bag after trimming his hair in the Zarya module of the International Space Station.

Selective loss of polymorphic mating types is associated with rapid phenotypic evolution during morphic speciation.

PubMed

Corl, Ammon; Davis, Alison R; Kuchta, Shawn R; Sinervo, Barry

2010-03-02

Polymorphism may play an important role in speciation because new species could originate from the distinctive morphs observed in polymorphic populations. However, much remains to be understood about the process by which morphs found new species. To detail the steps of this mode of speciation, we studied the geographic variation and evolutionary history of a throat color polymorphism that distinguishes the "rock-paper-scissors" mating strategies of the side-blotched lizard, Uta stansburiana. We found that the polymorphism is geographically widespread and has been maintained for millions of years. However, there are many populations with reduced numbers of throat color morphs. Phylogenetic reconstruction showed that the polymorphism is ancestral, but it has been independently lost eight times, often giving rise to morphologically distinct subspecies/species. Changes to the polymorphism likely involved selection because the allele for one particular male strategy, the "sneaker" morph, has been lost in all cases. Polymorphism loss was associated with accelerated evolution of male size, female size, and sexual dimorphism, which suggests that polymorphism loss can promote rapid divergence among populations and aid species formation.

Influence of Etching Mode on Enamel Bond Durability of Universal Adhesive Systems.

PubMed

Suzuki, T; Takamizawa, T; Barkmeier, W W; Tsujimoto, A; Endo, H; Erickson, R L; Latta, M A; Miyazaki, M

2016-01-01

The purpose of this study was to determine the enamel bond durability of three universal adhesives in different etching modes through fatigue testing. The three universal adhesives used were Scotchbond Universal, Prime&Bond Elect universal dental adhesive, and All-Bond Universal light-cured dental adhesive. A single-step self-etch adhesive, Clearfil S 3 Bond Plus was used as a control. The shear bond strength (SBS) and shear fatigue strength (SFS) to human enamel were evaluated in total-etch mode and self-etch mode. A stainless steel metal ring with an internal diameter of 2.4 mm was used to bond the resin composite to the flat-ground (4000-grit) tooth surfaces for determination of both SBS and SFS. For each enamel surface treatment, 15 specimens were prepared for SBS and 30 specimens for SFS. The staircase method for fatigue testing was then used to determine the SFS of the resin composite bonded to the enamel using 10-Hz frequencies for 50,000 cycles or until failure occurred. Scanning electron microscopy was used to observe representative debonded specimen surfaces and the resin-enamel interfaces. A two-way analysis of variance and the Tukey post hoc test were used for analysis of the SBS data, whereas a modified t-test with Bonferroni correction was used for the SFS data. All adhesives in total-etch mode showed significantly higher SBS and SFS values than those in self-etch mode. Although All-Bond Universal in self-etch mode showed a significantly lower SBS value than the other adhesives, there was no significant difference in SFS values among the adhesives in this mode. All adhesives showed higher SFS:SBS ratios in total-etch mode than in self-etch mode. With regard to the adhesive systems used in this study, universal adhesives showed higher enamel bond strengths in total-etch mode. Although the influence of different etching modes on the enamel-bonding performance of universal adhesives was found to be dependent on the adhesive material, total-etch mode effectively increased the enamel bond strength and durability, as measured by fatigue testing.

Study of the Impact of Heat Treatment Modes on Formation of Microstructure and a Given Set of Mechanical Properties of High-Strength Flat Products with Guaranteed Hardness (400 to 450 HB) from Low-Alloyed Steel

NASA Astrophysics Data System (ADS)

Matrosov, M. Yu; Martynov, P. G.; Goroshko, T. V.; Zvereva, M. I.; Mitrofanov, A. V.; Barabash, K. Yu

2017-12-01

The results of the study of influence of heat treatment modes on microstructure, size and shape of grains, mechanical properties of high-strength flat products from low-alloyed C-Mn-Cr-Si-Mo steel microalloyed by boron are presented. Heat treatment modes, which provide a combination of high impact viscosity at negative temperatures and guaranteed hardness, are determined.

Influence of nano-structured alumina coating on shear bond strength between Y-TZP ceramic and various dual-cured resin cements.

PubMed

Lee, Jung-Jin; Choi, Jung-Yun; Seo, Jae-Min

2017-04-01

The purpose of this study was to evaluate the effect of nano-structured alumina surface coating on shear bond strength between Y-TZP ceramic and various dual-cured resin cements. A total of 90 disk-shaped zirconia specimens (HASS CO., Gangneung, Korea) were divided into three groups by surface treatment method: (1) airborne particle abrasion, (2) tribochemicalsilica coating, and (3) nano-structured alumina coating. Each group was categorized into three subgroups of ten specimens and bonded with three different types of dual-cured resin cements. After thermocycling, shear bond strength was measured and failure modes were observed through FE-SEM. Two-way ANOVA and the Tukey's HSD test were performed to determine the effects of surface treatment method and type of cement on bond strength ( P <.05). To confirm the correlation of surface treatment and failure mode, the Chi-square test was used. Groups treated with the nanostructured alumina coating showed significantly higher shear bond strength compared to other groups treated with airborne particle abrasion or tribochemical silica coating. Clearfil SA Luting showed a significantly higher shear bond strength compared to RelyX ARC and RelyX Unicem. The cohesive failure mode was observed to be dominant in the groups treated with nano-structured alumina coating, while the adhesive failure mode was prevalent in the groups treated with either airborne particle abrasion or tribochemical silica coating. Nano-structured alumina coating is an effective zirconia surface treatment method for enhancing the bond strength between Y-TZP ceramic and various dual-cured resin cements.

Reverse indentation size effects in gamma irradiated blood compatible blend films of chitosan-poly (vinyl alcohol) for possible medical applications.

PubMed

Bisen, D S; Bhatt, Rinkesh; Bajpai, A K; Bajpai, R; Katare, R

2017-02-01

In the present work binary blends of polyvinyl alcohol (PVA) and chitosan (CS) were prepared by solution cast method and characterized by analytical methods like FTIR, XRD and SEM for seeking structural and morphological information. The blends were exposed to gamma radiation and evaluated for their improved mechanical strength. It was found that the tensile strength and microhardness increased after irradiation of CS-PVA films. Plastic effect due to absorption of water molecules and scissoring effect due to gamma irradiation were found to decrease the softness or increase the microhardness of the blends. Improved mechanical properties were attributed to intermolecular and intramolecular hydrogen bonds and adhesive nature of the blends also. The blends were also investigated for water intake behavior and in vitro blood compatibility property on the basis of certain in vitro tests like protein adsorption, haemolysis and blood clot formation on the un-irradiated and irradiated blend samples. The increased % swelling with time could be assigned to the fact that increasing water content facilitates the phase separation process within the blend which results in advancement in interstitial nano-void spaces which are occupied by water molecules. The blood compatibility results showed that when the amount of CS was varied from 0.5% to 2%, the amount of blood clot and percent haemolysis decreased while the protein adsorption increased with increasing CS content of the blend films. Copyright © 2016 Elsevier B.V. All rights reserved.

Defying ageing: An expectation for dentine bonding with universal adhesives?

PubMed

Zhang, Zheng-yi; Tian, Fu-cong; Niu, Li-na; Ochala, Kirsten; Chen, Chen; Fu, Bai-ping; Wang, Xiao-yan; Pashley, David H; Tay, Franklin R

2016-02-01

The present study evaluated the long-term dentine bonding effectiveness of five universal adhesives in etch-and-rinse or self-etch mode after 12 months of water-ageing. The adhesives evaluated included All-Bond Universal, Clearfil Universal Bond, Futurabond U Prime&Bond Elect and Scotchbond Universal. Microtensile bond strength and transmission electron microscopy of the resin-dentine interfaces created in human coronal dentine were examined after 24h or 12 months. Microtensile bond strength were significantly affected by bonding strategy (etch-and-rinse vs self-etch) and ageing (24h vs 12 months). All subgroups showed significantly decreased bond strength after ageing except for Prime&Bond Elect and Scotchbond Universal used in self-etch mode. All five adhesives employed in etch-and-rinse mode exhibited ultrastructural features characteristic of collagen degradation and resin hydrolysis. A previously-unobserved inside-out collagen degradation pattern was identified in hybrid layers created by 10-MDP containing adhesives (All-Bond Universal, Scotchbond Universal and Clearfil Universal Bond) in the etch-and-rinse mode, producing partially degraded collagen fibrils with intact periphery and a hollow core. In the self-etch mode, all adhesives except for Prime&Bond Elect exhibited degradation of the collagen fibrils along the thin hybrid layers. The three 10-MDP containing universal adhesives did not protect surface collagen fibrils from degradation when bonding was performed in the self-etch mode. Despite the adjunctive conclusion that bonds created by universal adhesives in the self-etch bonding mode are more resistant to decline in bond strength when compared with those bonds created using the etch-and-rinse mode, bonds created by universal adhesives are generally incapable of defying ageing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Numerical Model for the Study of the Strength and Failure Modes of Rock Containing Non-Persistent Joints

NASA Astrophysics Data System (ADS)

Vergara, Maximiliano R.; Van Sint Jan, Michel; Lorig, Loren

2016-04-01

The mechanical behavior of rock containing parallel non-persistent joint sets was studied using a numerical model. The numerical analysis was performed using the discrete element software UDEC. The use of fictitious joints allowed the inclusion of non-persistent joints in the model domain and simulating the progressive failure due to propagation of existing fractures. The material and joint mechanical parameters used in the model were obtained from experimental results. The results of the numerical model showed good agreement with the strength and failure modes observed in the laboratory. The results showed the large anisotropy in the strength resulting from variation of the joint orientation. Lower strength of the specimens was caused by the coalescence of fractures belonging to parallel joint sets. A correlation was found between geometrical parameters of the joint sets and the contribution of the joint sets strength in the global strength of the specimen. The results suggest that for the same dip angle with respect to the principal stresses; the uniaxial strength depends primarily on the joint spacing and the angle between joints tips and less on the length of the rock bridges (persistency). A relation between joint geometrical parameters was found from which the resulting failure mode can be predicted.

Experimental Study On The Effect Of Micro-Cracks On Brazilian Tensile Strength

NASA Astrophysics Data System (ADS)

Wang, Xiangyu

2015-12-01

For coal mine ground control issues, it is necessary to propose a failure criteria accounting for the transversely isotropic behaviors of rocks. Hence, it is very helpful to provide experimental data for the validation of the failure criteria. In this paper, the method for preparing transversely isotropic specimens and the scheme of the Brazilian tensile strength test are presented. Results obtained from Brazilian split tests under dry and water-saturated conditions reflect the effect of the development direction β of the structural plane, such as the bedding fissure, on the tensile strength, ultimate displacement, failure mode, and the whole splitting process. The results show that the tensile strength decreases linearly with increasing β. The softening coefficient of the tensile strength shows a sinusoidal function. The values of the slope and inflection point for the curve vary at the different stages of the Brazilian test. The failure mode of the rock specimen presented in this paper generally coincides with the standard Brazilian splitting failure mode. Based on the test results, the major influencing factors for the Brazilian splitting strength are analyzed and a mathematical model for solving the Brazilian splitting strength is proposed. The findings in this paper would greatly benefit the coal mine ground control studies when the surrounding rocks of interest show severe transversely isotropic behaviors.

High strength fusion splicing of hollow core photonic crystal fiber and single-mode fiber by large offset reheating

NASA Astrophysics Data System (ADS)

Song, Ningfang; Wu, Chunxiao; Luo, Wenyong; Zhang, Zuchen; Li, Wei

2016-12-01

High strength fusion splicing hollow core photonic crystal fiber (HC-PCF) and single-mode fiber (SMF) requires sufficient energy, which results in collapse of the air holes inside HC-PCF. Usually the additional splice loss induced by the collapse of air holes is too large. By large offset reheating, the collapse length of HC-PCF is reduced, thus the additional splice loss induced by collapse is effectively suppressed. This method guarantees high-strength fusion splicing between the two types of fiber with a low splice loss. The strength of the splice compares favorably with the strength of HC-PCF itself. This method greatly improves the reliability of splices between HC-PCFs and SMFs.

Mission Specialist (MS) Lenoir cuts Pilot Overmyer's hair on middeck

NASA Technical Reports Server (NTRS)

1982-01-01

Mission Specialist (MS) Lenoir, using hairbrush and scissors, cuts Pilot Overmyer's hair and trims his sideburns in front of forward middeck lockers. Personal hygiene kit (open), towels, meal tray assemblies, and field sequential (FS) crew cabincamera are attached to lockers.

Wakata haircut in the Service Module (SM)

NASA Image and Video Library

2009-04-04

ISS018-E-044602 (4 April 2009) --- Japan Aerospace Exploration Agency (JAXA) astronaut Koichi Wakata, Expedition 18/19 flight engineer, trims his hair in the Zarya module of the International Space Station, using scissors and a vacuum device to garner freshly cut hair.

Fracture modes in off-axis fiber composites

NASA Technical Reports Server (NTRS)

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

1978-01-01

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

Experimental study on compressive strength of sediment brick masonry

NASA Astrophysics Data System (ADS)

Woen, Ean Lee; Malek, Marlinda Abdul; Mohammed, Bashar S.; Chao-Wei, Tang; Tamunif, Muhammad Thaqif

2018-02-01

The effects of pre-wetted unit bricks, mortar type and slenderness ratio of prisms on the compressive strength and failure mode of newly developed sediment brick have been evaluated and compared to clay brick and cement-sand bricks. The results show that pre-wetted sediment brick masonry exhibits higher compressive strength of up to 20% compared to the dry sediment masonry. Using cement-lime mortar leads to lower compressive strength compared to cement mortar. However, the sediment brick masonry with the cement lime mortar exhibit higher compressive strength in comparison with cement mortar masonry. More of diagonal shear cracks have been observed in the failure mode of the sediment bricks masonry compared to clay and cement-sand bricks masonry that show mostly vertical cracks and crushing. The sediment unit bricks display compressive strength in between clay and cement-sand bricks.

Using the phase shift to asymptotically characterize the dipolar mixed modes in post-main-sequence stars

NASA Astrophysics Data System (ADS)

Jiang, C.; Christensen-Dalsgaard, J.; Cunha, M.

2018-03-01

Mixed modes have been extensively observed in post-main-sequence stars by the Kepler and CoRoT space missions. The mixture of the p and g modes can be measured by the dimensionless coefficient q, the so-called coupling strength factor. In this paper, we discuss the utility of the phase shifts θ from the eigenvalue condition for mixed modes as a tool to characterize dipolar mixed modes from the theoretical as well as the practical point of view. Unlike the coupling strength, whose variation in a given star is very small over the relevant frequency range, the phase shifts vary significantly for different modes. The analysis in terms of θ can also provide a better understanding of the pressure and gravity radial order for a given mixed mode. Observed frequencies of the Kepler red-giant star KIC 3744043 are used to test the method. The results are very promising.

Vibrational properties of quasi-two-dimensional colloidal glasses with varying interparticle attraction.

PubMed

Gratale, Matthew D; Ma, Xiaoguang; Davidson, Zoey S; Still, Tim; Habdas, Piotr; Yodh, A G

2016-10-01

We measure the vibrational modes and particle dynamics of quasi-two-dimensional colloidal glasses as a function of interparticle interaction strength. The interparticle attractions are controlled via a temperature-tunable depletion interaction. Specifically, the interparticle attraction energy is increased gradually from a very small value (nearly hard-sphere) to moderate strength (∼4k_{B}T), and the variation of colloidal particle dynamics and vibrations are concurrently probed. The particle dynamics slow monotonically with increasing attraction strength, and the particle motions saturate for strengths greater than ∼2k_{B}T, i.e., as the system evolves from a nearly repulsive glass to an attractive glass. The shape of the phonon density of states is revealed to change with increasing attraction strength, and the number of low-frequency modes exhibits a crossover for glasses with weak compared to strong interparticle attraction at a threshold of ∼2k_{B}T. This variation in the properties of the low-frequency vibrational modes suggests a new means for distinguishing between repulsive and attractive glass states.

Characterizing the radial content of orbital-angular-momentum photonic states impaired by weak-to-strong atmospheric turbulence.

PubMed

Chen, Chunyi; Yang, Huamin

2016-08-22

The changes in the radial content of orbital-angular-momentum (OAM) photonic states described by Laguerre-Gaussian (LG) modes with a radial index of zero, suffering from turbulence-induced distortions, are explored by numerical simulations. For a single-photon field with a given LG mode propagating through weak-to-strong atmospheric turbulence, both the average LG and OAM mode densities are dependent only on two nondimensional parameters, i.e., the Fresnel ratio and coherence-width-to-beam-radius (CWBR) ratio. It is found that atmospheric turbulence causes the radially-adjacent-mode mixing, besides the azimuthally-adjacent-mode mixing, in the propagated photonic states; the former is relatively slighter than the latter. With the same Fresnel ratio, the probabilities that a photon can be found in the zero-index radial mode of intended OAM states in terms of the relative turbulence strength behave very similarly; a smaller Fresnel ratio leads to a slower decrease in the probabilities as the relative turbulence strength increases. A photon can be found in various radial modes with approximately equal probability when the relative turbulence strength turns great enough. The use of a single-mode fiber in OAM measurements can result in photon loss and hence alter the observed transition probability between various OAM states. The bit error probability in OAM-based free-space optical communication systems that transmit photonic modes belonging to the same orthogonal LG basis may depend on what digit is sent.

Boxing Up a Mini Herd: Art Put to Pasture.

ERIC Educational Resources Information Center

Zimmerman, Midge

2002-01-01

Presents an art project for high school students that was inspired by the 1999 "Cows on Parade" exhibition in Chicago (Illinois). Explains that students used old Gateway computer boxes to create their own cows using the box, scissors, and a hot-glue gun. (CMK)

Emergence of unusual coexistence states in cyclic game systems.

PubMed

Park, Junpyo; Do, Younghae; Jang, Bongsoo; Lai, Ying-Cheng

2017-08-07

Evolutionary games of cyclic competitions have been extensively studied to gain insights into one of the most fundamental phenomena in nature: biodiversity that seems to be excluded by the principle of natural selection. The Rock-Paper-Scissors (RPS) game of three species and its extensions [e.g., the Rock-Paper-Scissors-Lizard-Spock (RPSLS) game] are paradigmatic models in this field. In all previous studies, the intrinsic symmetry associated with cyclic competitions imposes a limitation on the resulting coexistence states, leading to only selective types of such states. We investigate the effect of nonuniform intraspecific competitions on coexistence and find that a wider spectrum of coexistence states can emerge and persist. This surprising finding is substantiated using three classes of cyclic game models through stability analysis, Monte Carlo simulations and continuous spatiotemporal dynamical evolution from partial differential equations. Our finding indicates that intraspecific competitions or alternative symmetry-breaking mechanisms can promote biodiversity to a broader extent than previously thought.

Antibiotic-mediated antagonism leads to a bacterial game of rock-paper-scissors in vivo

NASA Astrophysics Data System (ADS)

Kirkup, Benjamin C.; Riley, Margaret A.

2004-03-01

Colicins are narrow-spectrum antibiotics produced by and active against Escherichia coli and its close relatives. Colicin-producing strains cannot coexist with sensitive or resistant strains in a well-mixed culture, yet all three phenotypes are recovered in natural populations. Recent in vitro results conclude that strain diversity can be promoted by colicin production in a spatially structured, non-transitive interaction, as in the classic non-transitive model rock-paper-scissors (RPS). In the colicin version of the RPS model, strains that produce colicins (C) kill sensitive (S) strains, which outcompete resistant (R) strains, which outcompete C strains. Pairwise in vitro competitions between these three strains are resolved in a predictable order (C beats S, S beats R, and R beats C), but the complete system of three strains presents the opportunity for dynamic equilibrium. Here we provide conclusive evidence of an in vivo antagonistic role for colicins and show that colicins (and potentially other bacteriocins) may promote, rather than eliminate, microbial diversity in the environment.

Zealotry promotes coexistence in the rock-paper-scissors model of cyclic dominance

NASA Astrophysics Data System (ADS)

Verma, Gunjan; Chan, Kevin; Swami, Ananthram

2015-11-01

Cyclic dominance models, such as the classic rock-paper-scissors (RPS) game, have found real-world applications in biology, ecology, and sociology. A key quantity of interest in such models is the coexistence time, i.e., the time until at least one population type goes extinct. Much recent research has considered conditions that lengthen coexistence times in an RPS model. A general finding is that coexistence is promoted by localized spatial interactions (low mobility), while extinction is fostered by global interactions (high mobility). That is, there exists a mobility threshold which separates a regime of long coexistence from a regime of rapid collapse of coexistence. The key finding of our paper is that if zealots (i.e., nodes able to defeat others while themselves being immune to defeat) of even a single type exist, then system coexistence time can be significantly prolonged, even in the presence of global interactions. This work thus highlights a crucial determinant of system survival time in cyclic dominance models.

Genome editing: the road of CRISPR/Cas9 from bench to clinic

PubMed Central

Eid, Ayman; Mahfouz, Magdy M

2016-01-01

Molecular scissors engineered for site-specific modification of the genome hold great promise for effective functional analyses of genes, genomes and epigenomes and could improve our understanding of the molecular underpinnings of disease states and facilitate novel therapeutic applications. Several platforms for molecular scissors that enable targeted genome engineering have been developed, including zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and, most recently, clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated-9 (Cas9). The CRISPR/Cas9 system's simplicity, facile engineering and amenability to multiplexing make it the system of choice for many applications. CRISPR/Cas9 has been used to generate disease models to study genetic diseases. Improvements are urgently needed for various aspects of the CRISPR/Cas9 system, including the system's precision, delivery and control over the outcome of the repair process. Here, we discuss the current status of genome engineering and its implications for the future of biological research and gene therapy. PMID:27741224

The rock-paper-scissors game and the evolution of alternative male strategies

NASA Astrophysics Data System (ADS)

Sinervo, B.; Lively, C. M.

1996-03-01

MANY species exhibit colour polymorphisms associated with alternative male reproductive strategies, including territorial males and 'sneaker males' that behave and look like females1-3. The prevalence of multiple morphs is a challenge to evolutionary theory because a single strategy should prevail unless morphs have exactly equal fitness4,5 or a fitness advantage when rare6,7. We report here the application of an evolutionary stable strategy model to a three-morph mating system in the side-blotched lizard. Using parameter estimates from field data, the model predicted oscillations in morph frequency, and the frequencies of the three male morphs were found to oscillate over a six-year period in the field. The fitnesses of each morph relative to other morphs were non-transitive in that each morph could invade another morph when rare, but was itself invadable by another morph when common. Concordance between frequency-dependent selection and the among-year changes in morph fitnesses suggest that male interactions drive a dynamic 'rock-paper-scissors' game7.

Endoscopic submucosal dissection of a rectal carcinoid tumor using grasping type scissors forceps

PubMed Central

Akahoshi, Kazuya; Motomura, Yasuaki; Kubokawa, Masaru; Matsui, Noriaki; Oda, Manami; Okamoto, Risa; Endo, Shingo; Higuchi, Naomi; Kashiwabara, Yumi; Oya, Masafumi; Akahane, Hidefumi; Akiba, Haruo

2009-01-01

Endoscopic submucosal dissection (ESD) with a knife is a technically demanding procedure associated with a high complication rate. The shortcomings of this method are the inability to fix the knife to the target lesion, and compression of the lesion. These can lead to major complications such as perforation and bleeding. To reduce the risk of complications related to ESD, we developed a new grasping type scissors forceps (GSF), which can grasp and incise the targeted tissue using electrosurgical current. Colonoscopy on a 55-year-old woman revealed a 10-mm rectal submucosal nodule. The histological diagnosis of the specimen obtained by biopsy was carcinoid tumor. Endoscopic ultrasonography demonstrated a hypoechoic solid tumor limited to the submucosa without lymph node involvement. It was safely and accurately resected without unexpected incision by ESD using a GSF. No delayed hemorrhage or perforation occurred. Histological examination confirmed the carcinoid tumor was completely excised with negative resection margin. PMID:19418591

Four-state rock-paper-scissors games in constrained Newman-Watts networks.

PubMed

Zhang, Guo-Yong; Chen, Yong; Qi, Wei-Kai; Qing, Shao-Meng

2009-06-01

We study the cyclic dominance of three species in two-dimensional constrained Newman-Watts networks with a four-state variant of the rock-paper-scissors game. By limiting the maximal connection distance Rmax in Newman-Watts networks with the long-range connection probability p , we depict more realistically the stochastic interactions among species within ecosystems. When we fix mobility and vary the value of p or Rmax, the Monte Carlo simulations show that the spiral waves grow in size, and the system becomes unstable and biodiversity is lost with increasing p or Rmax. These results are similar to recent results of Reichenbach et al. [Nature (London) 448, 1046 (2007)], in which they increase the mobility only without including long-range interactions. We compared extinctions with or without long-range connections and computed spatial correlation functions and correlation length. We conclude that long-range connections could improve the mobility of species, drastically changing their crossover to extinction and making the system more unstable.

Genome editing: the road of CRISPR/Cas9 from bench to clinic.

PubMed

Eid, Ayman; Mahfouz, Magdy M

2016-10-14

Molecular scissors engineered for site-specific modification of the genome hold great promise for effective functional analyses of genes, genomes and epigenomes and could improve our understanding of the molecular underpinnings of disease states and facilitate novel therapeutic applications. Several platforms for molecular scissors that enable targeted genome engineering have been developed, including zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and, most recently, clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated-9 (Cas9). The CRISPR/Cas9 system's simplicity, facile engineering and amenability to multiplexing make it the system of choice for many applications. CRISPR/Cas9 has been used to generate disease models to study genetic diseases. Improvements are urgently needed for various aspects of the CRISPR/Cas9 system, including the system's precision, delivery and control over the outcome of the repair process. Here, we discuss the current status of genome engineering and its implications for the future of biological research and gene therapy.

Strain Rate Dependency of Fracture Toughness, Energy Release Rate and Geomechanical Attributes of Select Indian Shales

NASA Astrophysics Data System (ADS)

Mahanta, B.; Vishal, V.; Singh, T. N.; Ranjith, P.

2016-12-01

In addition to modern improved technology, it requires detailed understanding of rock fractures for the purpose of enhanced energy extraction through hydraulic fracturing of gas shales and geothermal energy systems. The understanding of rock fracture behavior, patterns and properties such as fracture toughness; energy release rate; strength and deformation attributes during fracturing hold significance. Environmental factors like temperature, pressure, humidity, water vapor and experimental condition such as strain rate influence the estimation of these properties. In this study, the effects of strain rates on fracture toughness, energy release rate as well as geomechanical properties like uniaxial compressive strength, Young's modulus, failure strain, tensile strength, and brittleness index of gas shales were investigated. In addition to the rock-mechanical parameters, the fracture toughness and the energy release rates were measured for three different modes viz. mode I, mixed mode (I-II) and mode II. Petrographic and X-ray diffraction (XRD) analyses were performed to identify the mineral composition of the shale samples. Scanning electron microscope (SEM) analyses were conducted to have an insight about the strain rate effects on micro-structure of the rock. The results suggest that the fracture toughness; the energy release rate as well as other geomechanical properties are a function of strain rates. At high strain rates, the strength and stiffness of shale increases which in turn increases the fracture toughness and the energy release rate of shale that may be due to stress redistribution during grain fracturing. The fracture toughness and the strain energy release rates for all the modes (I/I-II/II) are comparable at lower strain rates, but they vary considerably at higher strain rates. In all the cases, mode I and mode II fracturing requires minimum and maximum applied energy, respectively. Mode I energy release rate is maximum, compared to the other modes.

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

Hidayat, Arif, E-mail: arif.hidayat.fmipa@um.ac.id; Latifah, Eny; Kurniati, Diana

This study investigated the influence of refraction index strength on the light propagation in refraction index-varied dielectric material. This dielectric material served as photonic lattice. The behavior of light propagation influenced by variation of refraction index in photonic lattice was investigated. Modes of the guiding light were determined numerically using squared-operator iteration method. It was found that the greater the strength of refraction index, the smaller the guiding modes.

Mechanical properties of contemporary composite resins and their interrelations.

PubMed

Thomaidis, Socratis; Kakaboura, Afrodite; Mueller, Wolf Dieter; Zinelis, Spiros

2013-08-01

To characterize a spectrum of mechanical properties of four representative types of modern dental resin composites and to investigate possible interrelations. Four composite resins were used, a microhybrid (Filtek Z-250), a nanofill (Filtek Ultimate), a nanohybrid (Majesty Posterior) and an ormocer (Admira). The mechanical properties investigated were Flexural Modulus and Flexural Strength (three point bending), Brinell Hardness, Impact Strength, mode I and mode II fracture toughness employing SENB and Brazilian tests and Work of Fracture. Fractographic analysis was carried out in an SEM to determine the origin of fracture for specimens subjected to SENB, Brazilian and Impact Strength testing. The results were statistically analyzed employing ANOVA and Tukey post hoc test (a=0.05) while Pearson correlation was applied among the mechanical properties. Significant differences were found between the mechanical properties of materials tested apart from mode I fracture toughness measured by Brazilian test. The latter significantly underestimated the mode I fracture toughness due to analytical limitations and thus its validity is questionable. Fractography revealed that the origin of fracture is located at notches for fracture toughness tests and contact surface with pendulum for Impact Strength testing. Pearson analysis illustrated a strong correlation between modulus of elasticity and hardness (r=0.87) and a weak negative correlation between Work of Fracture and Flexural Modulus (r=-0.46) and Work of Fracture and Hardness (r=-0.44). Weak correlations were also allocated between Flexural Modulus and Flexural Strength (r=0.40), Flexural Strength and Hardness (r=0.39), and Impact Strength and Hardness (r=0.40). Since the four types of dental resin composite tested exhibited large differences among their mechanical properties differences in their clinical performance is also anticipated. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Two-mode mazer injected with V-type three-level atoms

NASA Astrophysics Data System (ADS)

Liang, Wen-Qing; Zhang, Zhi-Ming; Xie, Sheng-Wu

2003-12-01

The properties of the two-mode mazer operating on V-type three-level atoms are studied. The effect of the one-atom pumping on the two modes of the cavity field in number-state is asymmetric, that is, the atom emits a photon into one mode with some probability and absorbs a photon from the other mode with some other probability. This effect makes the steady-state photon distribution and the steady-state photon statistics asymmetric for the two modes. The diagram of the probability currents for the photon distribution, given by the analysis of the master equation, reveals that there is no detailed balance solution for the master equation. The computations show that the photon statistics of one mode or both modes can be sub-Poissonian, that the two modes can have anticorrelation or correlation, that the photon statistics increases with the increase of thermal photons and that the resonant position and strength of the photon statistics are influenced by the ratio of the two coupling strengths of the two modes. These properties are also discussed physically.

Shear Fracture of Dual Phase AHSS in the Process of Stamping: Macroscopic Failure Mode and Micro-level Metallographical Observation

NASA Astrophysics Data System (ADS)

Wang, Wurong; Wei, Xicheng; Yang, Jun; Shi, Gang

2011-08-01

Due to its excellent strength and formability combinations, dual phase (DP) steels offer the potential to improve the vehicle crashworthiness performance without increasing car body weight and have been increasingly used into new vehicles. However, a new type of crack mode termed as shear fracture is accompanied with the application of these high strength DP steel sheets. With the cup drawing experiment to identify the limit drawing ratio (LDR) of three DP AHSS with strength level from 600 MPa to 1000 MPa, the study compared and categorized the macroscopic failure mode of these three types of materials. The metallographical observation along the direction of crack was conducted for the DP steels to discover the micro-level propagation mechanism of the fracture.

Electrical tuning of the oscillator strength in type II InAs/GaInSb quantum wells for active region of passively mode-locked interband cascade lasers

NASA Astrophysics Data System (ADS)

Dyksik, Mateusz; Motyka, Marcin; Kurka, Marcin; Ryczko, Krzysztof; Misiewicz, Jan; Schade, Anne; Kamp, Martin; Höfling, Sven; Sęk, Grzegorz

2017-11-01

Two designs of active region for an interband cascade laser, based on double or triple GaInSb/InAs type II quantum wells (QWs), were compared with respect to passive mode-locked operation in the mid-infrared range around 4 µm. The layer structure and electron and hole wavefunctions under external electric field were engineered to allow controlling the optical transition oscillator strength and the resulting lifetimes. As a result, the investigated structures can mimic absorber-like and gain-like sections of a mode-locked device when properly polarized with opposite bias. A significantly larger oscillator strength tuning range for triple QWs was experimentally verified by Fourier-transform photoreflectance.

Vibrational autoionization of state-selective jet-cooled methanethiol (CH 3SH) investigated with infrared + vacuum-ultraviolet photoionization

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

Xie, Min; Shen, Zhitao; Pratt, S. T.

Vibrational autoionization of Rydberg states provides key information about nonadiabatic processes above an ionization threshold. In this work, we employed time-of-flight mass detection of CH 3SH + to record vibrational-state selective photo-ionization efficiency (PIE) spectra of jet-cooled methanethiol (CH 3SH) on exciting CH 3SH to a specific vibrationally excited state with an infrared (IR) laser, followed by excitation with a tunable laser in the vacuum-ultraviolet (VUV) region for ionization. Autoionizing Rydberg states assigned to the ns, np, nd and nf series are identified. When IR light at 2601 (ν 3, SH stretching mode) and 2948 cm -1 (ν 2, CHmore » 3 symmetric stretching mode) was employed, the Rydberg series converged to the respective vibrationally excited (ν 3 and ν 2) states of CH 3SH +. When IR light at 3014 cm -1 (overlapped ν 1/ν 9, CH 3 antisymmetric stretching and CH 2 antisymmetric stretching modes) was employed, Rydberg series converging to two vibrationally excited states (ν 1 and ν 9) of CH 3SH + were observed. When IR light at 2867 cm -1 (2ν 10, overtone of CH 3 deformation mode) and 2892 cm -1 (2ν 4, overtone of CH 2 scissoring mode) was employed, both Δν = -1 and Δν = -2 ionization transitions were observed; there is evidence for direct ionization from the initial state into the CH 3SH + (ν 4 + = 1) continuum. In all observed IR-VUV-PIE spectra, the ns and nd series show intensity greater than the other Rydberg series, which is consistent with the fact that the highest-occupied molecular orbital of CH 3SH is a p-like lone pair orbital on the S atom. Finally, the quantum yields for autoionization of various vibrational excited states are discussed. Values of ν 1 = 3035, ν 2 = 2884, ν 3 = 2514, and ν 9 = 2936 cm -1 for CH 3SH + derived from the converged limits agree satisfactorily with values observed for Ar-tagged CH 3SH + at 3026, 2879, 2502, and 2933 cm -1.« less

Vibrational autoionization of state-selective jet-cooled methanethiol (CH 3SH) investigated with infrared + vacuum-ultraviolet photoionization

DOE PAGES

Xie, Min; Shen, Zhitao; Pratt, S. T.; ...

2017-10-24

Vibrational autoionization of Rydberg states provides key information about nonadiabatic processes above an ionization threshold. In this work, we employed time-of-flight mass detection of CH 3SH + to record vibrational-state selective photo-ionization efficiency (PIE) spectra of jet-cooled methanethiol (CH 3SH) on exciting CH 3SH to a specific vibrationally excited state with an infrared (IR) laser, followed by excitation with a tunable laser in the vacuum-ultraviolet (VUV) region for ionization. Autoionizing Rydberg states assigned to the ns, np, nd and nf series are identified. When IR light at 2601 (ν 3, SH stretching mode) and 2948 cm -1 (ν 2, CHmore » 3 symmetric stretching mode) was employed, the Rydberg series converged to the respective vibrationally excited (ν 3 and ν 2) states of CH 3SH +. When IR light at 3014 cm -1 (overlapped ν 1/ν 9, CH 3 antisymmetric stretching and CH 2 antisymmetric stretching modes) was employed, Rydberg series converging to two vibrationally excited states (ν 1 and ν 9) of CH 3SH + were observed. When IR light at 2867 cm -1 (2ν 10, overtone of CH 3 deformation mode) and 2892 cm -1 (2ν 4, overtone of CH 2 scissoring mode) was employed, both Δν = -1 and Δν = -2 ionization transitions were observed; there is evidence for direct ionization from the initial state into the CH 3SH + (ν 4 + = 1) continuum. In all observed IR-VUV-PIE spectra, the ns and nd series show intensity greater than the other Rydberg series, which is consistent with the fact that the highest-occupied molecular orbital of CH 3SH is a p-like lone pair orbital on the S atom. Finally, the quantum yields for autoionization of various vibrational excited states are discussed. Values of ν 1 = 3035, ν 2 = 2884, ν 3 = 2514, and ν 9 = 2936 cm -1 for CH 3SH + derived from the converged limits agree satisfactorily with values observed for Ar-tagged CH 3SH + at 3026, 2879, 2502, and 2933 cm -1.« less

Quantifying Fish Backscattering using SONAR Instrument and Kirchhoff Ray Mode (KRM) Model

NASA Astrophysics Data System (ADS)

Manik, Henry M.

2016-08-01

Sonar instrument was used to study backscattering from tuna fish. Extraction of target strength, incidence angle, and frequency dependence of the backscattered signal for individual scatterer was important for biological information. For this purpose, acoustic measurement of fish backscatter was conducted in the laboratory. Characteristics and general trends of the target strength of fish with special reference to tuna fish were investigated by using a Kirchhoff Ray Mode (KRM) model. Backscattering strength were calculated for the KRM having typical morphological and physical parameters of actual fish. Those backscattering amplitudes were shown as frequency, body length, backscattering patterns, the density and sound speed dependences, and orientation dependence. These results were compared with experimentally measured target strength data and good agreement was found. Measurement and model showed the target strength from the fish are depend on the presence of swimbladder. Target Strength increase with increasing the frequency and fish length.

Collective modes of a two-dimensional Fermi gas at finite temperature

NASA Astrophysics Data System (ADS)

Mulkerin, Brendan C.; Liu, Xia-Ji; Hu, Hui

2018-05-01

We examine the breathing mode of a strongly interacting two-dimensional Fermi gas and the role of temperature on the anomalous breaking of scale invariance. By calculating the equation of state with different many-body T -matrix theories and the virial expansion, we obtain a hydrodynamic equation of the harmonically trapped Fermi gas (with trapping frequency ω0) through the local density approximation. By solving the hydrodynamic equations, we determine the breathing mode frequencies as a function of interaction strength and temperature. We find that the breathing mode anomaly depends sensitively on both interaction strength and temperature. In particular, in the strongly interacting regime, we predict a significant downshift of the breathing mode frequency, below the scale invariant value of 2 ω0 , for temperatures of the order of the Fermi temperature.

Selective Acid Etching Improves the Bond Strength of Universal Adhesive to Sound and Demineralized Enamel of Primary Teeth.

PubMed

Antoniazzi, Bruna Feltrin; Nicoloso, Gabriel Ferreira; Lenzi, Tathiane Larissa; Soares, Fabio Zovico Maxnuck; Rocha, Rachel de Oliveira

To evaluate the influence of enamel condition and etching strategy on bond strength of a universal adhesive in primary teeth. Thirty-six primary molars were randomly assigned to six groups (n = 6) according to the enamel condition (sound [S] and demineralized [DEM]/cariogenic challenge by pH cycling prior to restorative procedures) and adhesive system (Scotchbond Universal Adhesive [SBU]) used in either etch-and-rinse (ER) or selfetching (SE) mode, with Clearfil SE Bond as the self-etching control. The adhesives were applied to flat enamel surfaces and composite cylinders (0.72 mm2) were built up. After 24-h storage in water, specimens were subjected to the microshear test. Bond strength (MPa) data were analyzed using two-way ANOVA and Tukey's post-hoc tests (α = 0.05). Significant differences were found considering the factors adhesive system (p = 0.003) and enamel condition (p = 0.001). Demineralized enamel negatively affected the bond strength, with μSBS values approximately 50% lower than those obtained for sound enamel. SBU performed better in etch-and-rinse mode, and the bond strength found for SBU applied in self-etching mode was similar to that of CSE. Enamel etching with phosphoric acid improves the bond strength of a universal adhesive system to primary enamel. Demineralized primary enamel results in lower bond strength.

Fabric controls on the brittle failure of folded gneiss and schist

NASA Astrophysics Data System (ADS)

Agliardi, Federico; Zanchetta, Stefano; Crosta, Giovanni B.

2014-12-01

We experimentally studied the brittle failure behaviour of folded gneiss and schist. Rock fabric and petrography were characterised by meso-structural analyses, optical microscopy, X-ray diffraction, and SEM imaging. Uniaxial compression, triaxial compression and indirect tension laboratory tests were performed to characterise their strength and stress-strain behaviour. Fracture patterns generated in compression were resolved in 3D through X-ray computed tomography at different resolutions (30 to 625 μm). Uniaxial compression tests revealed relatively low and scattered values of unconfined compressive strength (UCS) and Young's modulus, with no obvious relationships with the orientation of foliation. Samples systematically failed in four brittle modes, involving different combinations of shear fractures along foliation or parallel to fold axial planes, or the development of cm-scale shear zones. Fracture quantification and microstructural analysis show that different failure modes occur depending on the mutual geometrical arrangement and degree of involvement of two distinct physical anisotropies, i.e. the foliation and the fold axial planes. The Axial Plane Anisotropy (APA) is related to micro-scale grain size reduction and shape preferred orientation within quartz-rich domains, and to mechanical rotation or initial crenulation cleavage within phyllosilicate-rich domains at fold hinge zones. In quartz-rich rocks (gneiss), fracture propagation through quartz aggregates forming the APA corresponds to higher fracture energy and strength than found for fracture through phyllosilicate-rich domains. This results in a strong dependence of strength on the failure mode. Conversely, in phyllosilicate-rich rocks (schist), all the failure modes are dominated by the strength of phyllosilicates, resulting in a sharp reduction of strength anisotropy.

Strength, hardness, and lattice vibrations of Z-carbon and W-carbon: First-principles calculations

NASA Astrophysics Data System (ADS)

Li, Zhiping; Gao, Faming; Xu, Ziming

2012-04-01

The strength, hardness, and lattice vibrations of two superhard carbon allotropies, Z-carbon and W-carbon are investigated by first-principles calculations. Phonon dispersion calculations indicate that Z-carbon and W-carbon are dynamically stable at least up to 300 GPa. The strength calculations reveal that the failure mode in Z-carbon is dominated by the tensile type, and the [010] direction is the weakest one. In W-carbon, the failure mode is dominated by the shear type, and the (101)[111¯] direction is the weakest one. Although the ideal strength of diamond is distinctly greater than that of Z-carbon and W-carbon, the tensile strength and shear strength for Z-carbon and W-carbon show much lower anisotropies than that of diamond. The hardness calculations indicate that the average hardness of Z-carbon is less than that of diamond but greater than that of the W-carbon, M-carbon, and body-centered-tetragonal-C4 carbon. The simulated Raman spectra show that the Ag modes at 1094 cm-1 for Z-carbon and 1109.7 cm-1 for W-carbon are in agreement with that of 1082 cm-1 observed in the experiment of cold-compressed graphite at 9.8 GPa.

The impact of artificially caries-affected dentin on bond strength of multi-mode adhesives

PubMed Central

Follak, Andressa Cargnelutti; Miotti, Leonardo Lamberti; Lenzi, Tathiane Larissa; Rocha, Rachel de Oliveira; Maxnuck Soares, Fabio Zovico

2018-01-01

Aim: The aim of this study is to evaluate the impact of dentin condition on bond strength of multi-mode adhesive systems (MMAS) to sound and artificially induced caries-affected dentin (CAD). Methods: Flat dentin surfaces of 112 bovine incisors were assigned to 16 subgroups (n = 7) according to the substrate condition (sound and CAD– pH-cycling for 14 days); adhesive systems (Scotchbond Universal, All-Bond Universal, Prime and Bond Elect, Adper Single Bond Plus and Clearfil SE Bond) and etching strategy (etch-and-rinse and self-etch). All systems were applied according to the manufacturer's instructions, and resin composite restorations were built. After 24 h of water storage, specimens were sectioned (0.8 mm2) and submitted to the microtensile test. Statistical Analysis: Data (MPa) were analyzed using three-way analysis of variance and Tukey's test (α = 0.05). Results: MMAS presented similar bond strength values, regardless etching strategy in each substrate condition. Bond strength values were lower when MMAS were applied to CAD in the etch-and-rinse strategy. Conclusion: The etching strategy did not influence the bond strength of MMAS to sound or CAD, considering each substrate separately. However, CAD impact negatively on bond strength of MMAS in etch-and rinse mode. PMID:29674813

Arctic Ocean Circulation Patterns Revealed by GRACE

NASA Astrophysics Data System (ADS)

Peralta-Ferriz, Cecilia; Morison, James H.; Wallace, John M.; Bonin, Jennifer A.; Zhang, Jinlun

2013-04-01

EOF analysis of non-seasonal, month-to-month variations in GRACE derived Arctic Ocean bottom pressure (OBP) yield three dominant modes. The first mode is a wintertime basin wide variation in mass associated with high atmospheric pressure (SLP) over Scandinavia. The second mode is a shift of mass from the central Arctic Ocean to the Siberian shelves due to low pressure over the basins, associated with the strength of the Arctic Oscillation. The third mode is a shift in mass between the Eastern and Western Siberian shelves, related to strength of the Beaufort High mainly in summer, and to eastward alongshore winds on the Barents Sea in winter. The PIOMAS and ECCO2 modeled OBP are consistent with the form of these modes and provide context in terms of variations in sea surface height. The models are used to investigate the ocean dynamics associated with each mode of OBP variability.

[Cyclic fatigue of Vita mark II machinable ceramics under Hertzian's contact].

PubMed

Liu, Wei-Cai; Zhang, Zhi-Shen; Huang, Cheng-Min; Chao, Yong-Lie; Wan, Qian-Bing

2006-08-01

To investigate the cyclic fatigue modes of Vita mark II machinable ceramics under Hertzian's contact. Hertzian's contact technique (WC spheres r = 3.18 mm) was used to investigate the cyclic fatigue of Vita mark II machinable ceramic. All specimens were fatigued by cyclic loading in moist environment, furthermore, surviving strength was examined by three point test and morphology damage observation. In homogeneous Vita mark II machinable ceramics, two fatigue damage modes existed after cyclic loading with spheres under moist environment, including conventional tensile-driven cone cracking (brittle mode) and shear-driven microdamage accumulation (quasi-plastic mode). The latter generated radial cracks and deeply penetrating secondary cone crack. Initial strength degradation were caused by the cone cracks, subsequent and much more deleterious loss was caused by radial cracks. Cyclic fatigue modes of Vita mark II machinable ceramics includes brittle and quasi-plastic mode.

Comparison of two interpolation methods for empirical mode decomposition based evaluation of radiographic femur bone images.

PubMed

Udhayakumar, Ganesan; Sujatha, Chinnaswamy Manoharan; Ramakrishnan, Swaminathan

2013-01-01

Analysis of bone strength in radiographic images is an important component of estimation of bone quality in diseases such as osteoporosis. Conventional radiographic femur bone images are used to analyze its architecture using bi-dimensional empirical mode decomposition method. Surface interpolation of local maxima and minima points of an image is a crucial part of bi-dimensional empirical mode decomposition method and the choice of appropriate interpolation depends on specific structure of the problem. In this work, two interpolation methods of bi-dimensional empirical mode decomposition are analyzed to characterize the trabecular femur bone architecture of radiographic images. The trabecular bone regions of normal and osteoporotic femur bone images (N = 40) recorded under standard condition are used for this study. The compressive and tensile strength regions of the images are delineated using pre-processing procedures. The delineated images are decomposed into their corresponding intrinsic mode functions using interpolation methods such as Radial basis function multiquadratic and hierarchical b-spline techniques. Results show that bi-dimensional empirical mode decomposition analyses using both interpolations are able to represent architectural variations of femur bone radiographic images. As the strength of the bone depends on architectural variation in addition to bone mass, this study seems to be clinically useful.

Experimental investigation of CNT effect on curved beam strength and interlaminar fracture toughness of CFRP laminates

NASA Astrophysics Data System (ADS)

Arca, M. A.; Coker, D.

2014-06-01

High mechanical properties and light weight structures of composite materials and advances in manufacturing processes have increased the use of composite materials in the aerospace and wind energy industries as a primary load carrying structures in complex shapes. However, use of composite materials in complex geometries such as L-shaped laminates creates weakness at the radius which causes delamination. Carbon nanotubes (CNTs) is preferred as a toughening materials in composite matrices due to their high mechanical properties and aspect ratios. However, effect of CNTs on curved beam strength (CBS) is not investigated in literature comprehensively. The objective of this study is to investigate the effect of CNT on Mode I and Mode II fracture toughness and CBS. L-shaped beams are fabric carbon/epoxy composite laminates manufactured by hand layup technique. Curved beam composite laminates were subjected to four point bending loading according to ASTM D6415/D6415M-06a. Double cantilever beam (DCB) tests and end notch flexure (ENF) tests were conducted to determine mode-I and mode-II fracture toughness, respectively. Preliminary results show that 3% CNT addition to the resin increased the mode-I fracture toughness by %25 and mode-II fracture toughness by %10 compared to base laminates. In contrast, no effect on curved beam strength was found.

Effects of Exercise Modality During Additional "High-Intensity Interval Training" on Aerobic Fitness and Strength in Powerlifting and Strongman Athletes.

PubMed

Androulakis-Korakakis, Patroklos; Langdown, Louis; Lewis, Adam; Fisher, James P; Gentil, Paulo; Paoli, Antonio; Steele, James

2018-02-01

Androulakis-Korakakis, P, Langdown, L, Lewis, A, Fisher, JP, Gentil, P, Paoli, A, and Steele, J. Effects of exercise modality during additional "high-intensity interval training" on aerobic fitness and strength in powerlifting and strongman athletes. J Strength Cond Res 32(2): 450-457, 2018-Powerlifters and strongman athletes have a necessity for optimal levels of muscular strength while maintaining sufficient aerobic capacity to perform and recover between events. High-intensity interval training (HIIT) has been popularized for its efficacy in improving both aerobic fitness and strength but never assessed within the aforementioned population group. This study looked to compare the effect of exercise modality, e.g., a traditional aerobic mode (AM) and strength mode (SM), during HIIT on aerobic fitness and strength. Sixteen well resistance-trained male participants, currently competing in powerlifting and strongman events, completed 8 weeks of approximately effort- and volume-matched HIIT in 2 groups: AM (cycling, n = 8) and SM (resistance training, n = 8). Aerobic fitness was measured as predicted V[Combining Dot Above]O2max using the YMCA 3 minutes step test and strength as predicted 1 repetition maximum from a 4-6RM test using a leg extension. Both groups showed significant improvements in both strength and aerobic fitness. There was a significant between-group difference for aerobic fitness improvements favoring the AM group (p ≤ 0.05). There was no between-group difference for change in strength. Magnitude of change using within-group effect size for aerobic fitness and strength was considered large for each group (aerobic fitness, AM = 2.6, SM = 2.0; strength, AM = 1.9, SM = 1.9). In conclusion, our results support enhanced strength and aerobic fitness irrespective of exercise modality (e.g., traditional aerobic and resistance training). However, powerlifters and strongman athletes wishing to enhance their aerobic fitness should consider HIIT using an aerobic HIIT mode.

Effect of double-layer application on bond quality of adhesive systems.

PubMed

Fujiwara, Satoshi; Takamizawa, Toshiki; Barkmeier, Wayne W; Tsujimoto, Akimasa; Imai, Arisa; Watanabe, Hidehiko; Erickson, Robert L; Latta, Mark A; Nakatsuka, Toshiyuki; Miyazaki, Masashi

2018-01-01

The aim of this study was to determine the effect of double-layer application of universal adhesives on the bond quality and compare to other adhesive systems. Two universal adhesives used were in this study: Scotchbond Universal (SU), [3M ESPE] and Prime & Bond elect (PE), [Dentsply Caulk]. The conventional single-step self-etch adhesives G-ӕnial Bond (GB), [GC Corporation.] and BeautiBond (BB), [Shofu Inc.], and a two-step self-etch adhesive, Optibond XTR (OX), [Kerr Corporation], were used as comparison adhesives. Shear bond strengths (SBS) and shear fatigue strengths (SFS) to human enamel and dentin were measured in single application mode and double application mode. For each test condition, 15 specimens were prepared for SBS testing and 30 specimens for SFS testing. Enamel and dentin SBS of the universal adhesives in the double application mode were significantly higher than those of the single application mode. In addition, the universal adhesives in the double application mode had significantly higher dentin SFS values than those of the single application mode. The two-step self-etch adhesive OX tended to have lower bond strengths in the double application mode, regardless of the test method or adherent substrate. The double application mode is effective in enhancing SBS and SFS of universal adhesives, but not conventional two-step self-etch adhesives. These results suggest that, although the double application mode may enhance the bonding quality of a universal adhesive, it may be counter-productive for two-step self-etch adhesives in clinical use. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of dentin dehydration and composite resin polymerization mode on bond strength of two self-etch adhesives.

PubMed

Samimi, Pooran; Alizadeh, Mehdi; Shirban, Farinaz; Davoodi, Amin; Khoroushi, Maryam

2016-01-01

Dual-cured composite resins are similar to self-cured composite resins in some of their clinical applications due to inadequate irradiation, lack of irradiation, or delayed irradiation. Therefore, incompatibility with self-etch adhesives (SEAs) should be taken into account with their use. On the other, the extent of dentin dehydration has a great role in the quality of adhesion of these resin materials to dentin. The aim of this study was to investigate the effect of dentin dehydration and composite resin polymerization mode on bond strength of two SEAs. A total of 120 dentinal specimens were prepared from extracted intact third molars. Half of the samples were dehydrated in ethanol with increasing concentrations. Then Clearfil SE Bond (CSEB) and Prompt L-Pop (PLP) adhesives were applied in the two groups. Cylindrical composite resin specimens were cured using three polymerization modes: (1) Immediate light-curing, (2) delayed light-curing after 20 min, and (3) self-curing. Bond strength was measured using universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed with two-way ANOVA and Duncan post hoc tests. Statistical significance was defined at P < 0.05. There were no significant differences for CSEB subgroups with hydrated and dehydrated dentin samples between the three different curing modes (P > 0.05). PLP showed significant differences between subgroups with the lowest bond strength in hydrated dentin with delayed light-curing and self-cured mode of polymerization. Within the limitations of this study, a delay in composite resin light-curing or using chemically cured composite resin had a deleterious effect on dentin bond strength of single-step SEAs used in the study.

Effect of dentin dehydration and composite resin polymerization mode on bond strength of two self-etch adhesives

PubMed Central

Samimi, Pooran; Alizadeh, Mehdi; Shirban, Farinaz; Davoodi, Amin; Khoroushi, Maryam

2016-01-01

Background: Dual-cured composite resins are similar to self-cured composite resins in some of their clinical applications due to inadequate irradiation, lack of irradiation, or delayed irradiation. Therefore, incompatibility with self-etch adhesives (SEAs) should be taken into account with their use. On the other, the extent of dentin dehydration has a great role in the quality of adhesion of these resin materials to dentin. The aim of this study was to investigate the effect of dentin dehydration and composite resin polymerization mode on bond strength of two SEAs. Materials and Methods: A total of 120 dentinal specimens were prepared from extracted intact third molars. Half of the samples were dehydrated in ethanol with increasing concentrations. Then Clearfil SE Bond (CSEB) and Prompt L-Pop (PLP) adhesives were applied in the two groups. Cylindrical composite resin specimens were cured using three polymerization modes: (1) Immediate light-curing, (2) delayed light-curing after 20 min, and (3) self-curing. Bond strength was measured using universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed with two-way ANOVA and Duncan post hoc tests. Statistical significance was defined at P < 0.05. Results: There were no significant differences for CSEB subgroups with hydrated and dehydrated dentin samples between the three different curing modes (P > 0.05). PLP showed significant differences between subgroups with the lowest bond strength in hydrated dentin with delayed light-curing and self-cured mode of polymerization. Conclusion: Within the limitations of this study, a delay in composite resin light-curing or using chemically cured composite resin had a deleterious effect on dentin bond strength of single-step SEAs used in the study. PMID:27041894

The effect of CFRP on retrofitting of damaged HSRC beams using AE technique

NASA Astrophysics Data System (ADS)

Soffian Noor, M. S.; Noorsuhada, M. N.

2017-12-01

This paper presents the effect of carbon fibre reinforced polymer (CFRP) on retrofitted high strength reinforced concrete (HSRC) beams using acoustic emission (AE) technique. Two RC beam parameters were prepared. The first was the control beam which was undamaged HSRC beam. The second was the damaged HSRC beam retrofitted with CFRP on the soffit. The main objective of this study is to assess the crack modes of HSRC beams using AE signal strength. The relationship between signal strength, load and time were analysed and discussed. The crack pattern observed from the visual observation was also investigated. HSRC beam retrofitted with CFRP produced high signal strength compared to control beam. It demonstrates the effect of the AE signal strength for interpretation and prediction of failure modes that might occur in the beam specimens.

Pigeons ("Columba Livia") Approach Nash Equilibrium in Experimental Matching Pennies Competitions

ERIC Educational Resources Information Center

Sanabria, Federico; Thrailkill, Eric

2009-01-01

The game of Matching Pennies (MP), a simplified version of the more popular Rock, Papers, Scissors, schematically represents competitions between organisms with incentives to predict each other's behavior. Optimal performance in iterated MP competitions involves the production of random choice patterns and the detection of nonrandomness in the…

NAVS Alternatives Set the Standard for Humane Education.

ERIC Educational Resources Information Center

Petty, Linda

1997-01-01

Describes some alternatives to dissection offered to teachers through the National Anti-Vivisection Society (NAVS) and other sources. These include models, CD-ROMs, and software that enable students to click on scalpels, scissors, and other instruments to cut through videotaped specimens. Also details the Dissection Hotline and the Dissection…

14 CFR 125.207 - Emergency equipment requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Administrator: Contents Quantity Adhesive bandage compressors, 1 in 16 Antiseptic swabs 20 Ammonia inhalants 10 Bandage compressors, 4 in 8 Triangular bandage compressors, 40 in 5 Arm splint, noninflatable 1 Leg splint, noninflatable 1 Roller bandage, 4 in 4 Adhesive tape, 1-in standard roll 2 Bandage scissors 1 Protective latex...

14 CFR 125.207 - Emergency equipment requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Administrator: Contents Quantity Adhesive bandage compressors, 1 in 16 Antiseptic swabs 20 Ammonia inhalants 10 Bandage compressors, 4 in 8 Triangular bandage compressors, 40 in 5 Arm splint, noninflatable 1 Leg splint, noninflatable 1 Roller bandage, 4 in 4 Adhesive tape, 1-in standard roll 2 Bandage scissors 1 Protective latex...

14 CFR 125.207 - Emergency equipment requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Administrator: Contents Quantity Adhesive bandage compressors, 1 in 16 Antiseptic swabs 20 Ammonia inhalants 10 Bandage compressors, 4 in 8 Triangular bandage compressors, 40 in 5 Arm splint, noninflatable 1 Leg splint, noninflatable 1 Roller bandage, 4 in 4 Adhesive tape, 1-in standard roll 2 Bandage scissors 1 Protective latex...

14 CFR 125.207 - Emergency equipment requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Administrator: Contents Quantity Adhesive bandage compressors, 1 in 16 Antiseptic swabs 20 Ammonia inhalants 10 Bandage compressors, 4 in 8 Triangular bandage compressors, 40 in 5 Arm splint, noninflatable 1 Leg splint, noninflatable 1 Roller bandage, 4 in 4 Adhesive tape, 1-in standard roll 2 Bandage scissors 1 Protective latex...

Apparatus for Assisting Childbirth

NASA Technical Reports Server (NTRS)

Smeltzer, Stanley S., III (Inventor); Lawson, Seth W. (Inventor)

1997-01-01

The invention consists of novel, scissors-like forceps in combination with optical monitoring hardware for measuring the extraction forces on a fetal head. The novel features of the forceps together with knowledge of real time forces on the fetal head enable a user to make a much safer delivery for mother and baby.

Science | AAAS

Science.gov Websites

be caused by haywire immune system eating brain connections CRISPR Stopping CRISPR's genome-editing scissors from snipping out of control CRISPR patent hearing produces no clear winner, only 'soft signals ' Did a Swedish researcher eat the first CRISPR meal ever served? Top articles in Careers dollars in a

University of Minnesota Duluth Engineering Design Challenge

DTIC Science & Technology

2015-03-23

on overall weight, size, lifting capacity, and ease of transporting. Many initial designs were considered including fire hose lift bags, hydraulic...Many initial designs were considered including fire hose lift bags, hydraulic lifts, a scissor lift, a spring loaded pawl tri-pod, and a pulley lift...26 Fire Hose

Melvin on FD during Expedition 16/STS-122 Joint Operations

NASA Image and Video Library

2008-02-10

S122-E-007587 (10 Feb. 2008) --- Astronaut Leland Melvin, STS-122 mission specialist, witnesses microgravity in action on the aft flight deck of Space Shuttle Atlantis while docked with the International Space Station. A package of food, scissors and a spoon float freely near Melvin.

Interview: Fenton Johnson.

ERIC Educational Resources Information Center

Creadick, Anna

1995-01-01

Fenton Johnson, an award-winning writer living in San Francisco, reflects on growing up in a large Catholic family in Appalachian Kentucky and the stigma associated with being gay. His latest novel, "Scissors, Papers, Rock," relates the story of a young man leaving the gay urban culture of San Francisco to return to the straight rural…

Rocks, Paper, Scissors: Best Practices in Peer Mentoring

ERIC Educational Resources Information Center

Bowden, Shelly Hudson

2014-01-01

In this article, Shelly Hudson Bowden, a kindergarten teacher for 14 years, offers her observations of peer-to-peer mentoring relationships among her kindergarten students that they formed and maintained. These mentoring relationships supported students' learning as they mentored one another in both "social" and "academic"…

Managing the Student Press: Consider Carefully before You Unsheath the Censor's Scissors.

ERIC Educational Resources Information Center

Sendor, Benjamin

1988-01-01

The United States Supreme Court's decision in "Hazelwood School District v. Kuhlmeier" gives school officials sweeping power over school-sponsored publications and other curricular and extracurricular activities. To avoid charges of squelching student expression, school boards should make sure that policies limit censorship to legitimate…

The effect of ring distortions on buckling of blunt conical shells. [Viking mission aeroshell

NASA Technical Reports Server (NTRS)

Heard, W. L., Jr.; Anderson, M. S.; Stephens, W. B.

1975-01-01

A rigorous analytical study of cones stiffened by many thin-gage, open-section rings is presented. The results are compared with data previously obtained from uniform pressure tests of the Viking mission flight aeroshell and of the Viking structural prototype aeroshells. A conventional analysis, in which the rings are modeled as discrete rigid cross sections, is shown to lead to large, unconservative strength predictions. A more sophisticated technique of modeling the rings as shell branches leads to much more realistic strength predictions and more accurately predicts the failure modes. It is also shown that if a small initial imperfection proportional to the shape of the buckling mode is assumed, the critical buckling modes from analysis and test are in agreement. However, the reduction in buckling strength from the perfect-shell predictions is small.

Association of height, body weight, age, and corneal diameter with calculated intraocular lens strength of adult horses.

PubMed

Mouney, Meredith C; Townsend, Wendy M; Moore, George E

2012-12-01

To determine whether differences exist in the calculated intraocular lens (IOL) strengths of a population of adult horses and to assess the association between calculated IOL strength and horse height, body weight, and age, and between calculated IOL strength and corneal diameter. 28 clinically normal adult horses (56 eyes). Axial globe lengths and anterior chamber depths were measured ultrasonographically. Corneal curvatures were determined with a modified photokeratometer and brightness-mode ultrasonographic images. Data were used in the Binkhorst equation to calculate the predicted IOL strength for each eye. The calculated IOL strengths were compared with a repeated-measures ANOVA. Corneal curvature values (photokeratometer vs brightness-mode ultrasonographic images) were compared with a paired t test. Coefficients of determination were used to measure associations. Calculated IOL strengths (range, 15.4 to 30.1 diopters) differed significantly among horses. There was a significant difference in the corneal curvatures as determined via the 2 methods. Weak associations were found between calculated IOL strength and horse height and between calculated IOL strength and vertical corneal diameter. Calculated IOL strength differed significantly among horses. Because only weak associations were detected between calculated IOL strength and horse height and vertical corneal diameter, these factors would not serve as reliable indicators for selection of the IOL strength for a specific horse.

Highly Sensitive Refractive Index Sensors with Plasmonic Nanoantennas-Utilization of Optimal Spectral Detuning of Fano Resonances.

PubMed

Mesch, Martin; Weiss, Thomas; Schäferling, Martin; Hentschel, Mario; Hegde, Ravi S; Giessen, Harald

2018-05-25

We analyze and optimize the performance of coupled plasmonic nanoantennas for refractive index sensing. The investigated structure supports a sub- and super-radiant mode that originates from the weak coupling of a dipolar and quadrupolar mode, resulting in a Fano-type spectral line shape. In our study, we vary the near-field coupling of the two modes and particularly examine the influence of the spectral detuning between them on the sensing performance. Surprisingly, the case of matched resonance frequencies does not provide the best sensor. Instead, we find that the right amount of coupling strength and spectral detuning allows for achieving the ideal combination of narrow line width and sufficient excitation strength of the subradiant mode, and therefore results in optimized sensor performance. Our findings are confirmed by experimental results and first-order perturbation theory. The latter is based on the resonant state expansion and provides direct access to resonance frequency shifts and line width changes as well as the excitation strength of the modes. Based on these parameters, we define a figure of merit that can be easily calculated for different sensing geometries and agrees well with the numerical and experimental results.

Experimental and numerical analysis of web stiffened cold-formed steel channel column with various types of edge stiffener

NASA Astrophysics Data System (ADS)

Manikandan, P.; Balaji, S.; Sukumar, S.; Sivakumar, M.

2017-06-01

This paper presents the strength and behaviour of web stiffened cold formed steel channel column with various types of edge stiffener under axial compression. An accurate finite element model is developed to simulate the tests results of the proposed section. The finite element model is verified by the test results and good correlation is achieved. The failure modes local, distortional, flexural buckling as well as the interaction between these modes is found in this study. The column strength predicted from the parametric study is compared with the nominal strength calculated by using the direct strength method for cold formed steel members. The reliability of this method is evaluated and suitable modification factor is proposed.

Polygyny, mate-guarding, and posthumous fertilization as alternative male mating strategies

PubMed Central

Zamudio, Kelly R.; Sinervo, Barry

2000-01-01

Alternative male mating strategies within populations are thought to be evolutionarily stable because different behaviors allow each male type to successfully gain access to females. Although alternative male strategies are widespread among animals, quantitative evidence for the success of discrete male strategies is available for only a few systems. We use nuclear microsatellites to estimate the paternity rates of three male lizard strategies previously modeled as a rock-paper-scissors game. Each strategy has strengths that allow it to outcompete one morph, and weaknesses that leave it vulnerable to the strategy of another. Blue-throated males mate-guard their females and avoid cuckoldry by yellow-throated “sneaker” males, but mate-guarding is ineffective against aggressive orange-throated neighbors. The ultradominant orange-throated males are highly polygynous and maintain large territories; they overpower blue-throated neighbors and cosire offspring with their females, but are often cuckolded by yellow-throated males. Finally, yellow-throated sneaker males sire offspring via secretive copulations and often share paternity of offspring within a female's clutch. Sneaker males sire more offspring posthumously, indicating that sperm competition may be an important component of their strategy. PMID:11106369

Effect of Oxygen Inhibition Layer of Universal Adhesives on Enamel Bond Fatigue Durability and Interfacial Characteristics With Different Etching Modes.

PubMed

Ouchi, H; Tsujimoto, A; Nojiri, K; Hirai, K; Takamizawa, T; Barkmeier, W W; Latta, M A; Miyazaki, M

The purpose of this study was to evaluate the effect of the oxygen inhibition layer of universal adhesive on enamel bond fatigue durability and interfacial characteristics with different etching modes. The three universal adhesives used were Scotchbond Universal Adhesive (3M ESPE, St Paul, MN, USA), Adhese Universal (Ivoclar Vivadent, Schaan, Lichtenstein), and G-Premio Bond (GC, Tokyo, Japan). The initial shear bond strength and shear fatigue strength to enamel was determined in the presence and absence of the oxygen inhibition layer, with and without phosphoric acid pre-etching. The water contact angle was also measured in all groups using the sessile drop method. The enamel bonding specimens with an oxygen inhibition layer showed significantly higher (p<0.05) initial shear bond strengths and shear fatigue strengths than those without, regardless of the adhesive type and etching mode. Moreover, the water contact angles on the specimens with an oxygen inhibition layer were significantly lower (p<0.05) than on those without, regardless of etching mode. The results of this study suggest that the oxygen inhibition layer of universal adhesives significantly increases the enamel bond fatigue durability and greatly changes interfacial characteristics, suggesting that the bond fatigue durability and interfacial characteristics of these adhesives strongly rely on its presence.

Peridynamics for failure and residual strength prediction of fiber-reinforced composites

NASA Astrophysics Data System (ADS)

Colavito, Kyle

Peridynamics is a reformulation of classical continuum mechanics that utilizes integral equations in place of partial differential equations to remove the difficulty in handling discontinuities, such as cracks or interfaces, within a body. Damage is included within the constitutive model; initiation and propagation can occur without resorting to special crack growth criteria necessary in other commonly utilized approaches. Predicting damage and residual strengths of composite materials involves capturing complex, distinct and progressive failure modes. The peridynamic laminate theory correctly predicts the load redistribution in general laminate layups in the presence of complex failure modes through the use of multiple interaction types. This study presents two approaches to obtain the critical peridynamic failure parameters necessary to capture the residual strength of a composite structure. The validity of both approaches is first demonstrated by considering the residual strength of isotropic materials. The peridynamic theory is used to predict the crack growth and final failure load in both a diagonally loaded square plate with a center crack, as well as a four-point shear specimen subjected to asymmetric loading. This study also establishes the validity of each approach by considering composite laminate specimens in which each failure mode is isolated. Finally, the failure loads and final failure modes are predicted in a laminate with various hole diameters subjected to tensile and compressive loads.

Differences in muscle activity during hand-dexterity tasks between women with arthritis and a healthy reference group.

PubMed

Brorsson, Sofia; Nilsdotter, Anna; Thorstensson, Carina; Bremander, Ann

2014-05-15

Impaired hand function is common in patients with arthritis and it affects performance of daily activities; thus, hand exercises are recommended. There is little information on the extent to which the disease affects activation of the flexor and extensor muscles during these hand-dexterity tasks. The purpose of this study was to compare muscle activation during such tasks in subjects with arthritis and in a healthy reference group. Muscle activation was measured in m. extensor digitorium communis (EDC) and in m. flexor carpi radialis (FCR) with surface electromyography (EMG) in women with rheumatoid arthritis (RA, n = 20), hand osteoarthritis (HOA, n = 16) and in a healthy reference group (n = 20) during the performance of four daily activity tasks and four hand exercises. Maximal voluntary isometric contraction (MVIC) was measured to enable intermuscular comparisons, and muscle activation is presented as %MVIC. The arthritis group used a higher %MVIC than the reference group in both FCR and EDC when cutting with a pair of scissors, pulling up a zipper and-for the EDC-also when writing with a pen and using a key (p < 0.02). The exercise "rolling dough with flat hands" required the lowest %MVIC and may be less effective in improving muscle strength. Women with arthritis tend to use higher levels of muscle activation in daily tasks than healthy women, and wrist extensors and flexors appear to be equally affected. It is important that hand training programs reflect real-life situations and focus also on extensor strength.

Dynamics of the earthquake source: An investigation of conditions under which velocity-weakening friction allows a self-healing versus crack-like mode of rupture

NASA Astrophysics Data System (ADS)

Zheng, Gutuan

Earthquake rupture processes occur by two basic modes: the expanding crack-like and the self-healing. For the expanding crack-like mode, ruptures on the fault keep expanding and seismic slips continue growing unless stopped by unbreakable barriers. For the self-healing mode, ruptures occur as a slip pulse propagating along the fault, with complete cessation of slip behind the pulse. A self-healing mode of rupture occurs on a velocity weakening fault under the following conditions: (1) Under-stressing; the background loading should be sufficiently low that no classical cracks can survive; (2) Aging; the rate- and state-dependent friction laws must allow restrengthening in truly stationary contact (Perrin et al., 1995). When V>0 we have tausb{strength}=tau, with tausb{strength}=tausb{strength}(V,theta) and tau=tausbsp{o}{b}-(mu/2c)V+phi along the fault surface, where tausb{strength} is the fault strength and tau is the stress. Other notations are slip velocity V, state variable theta, shear modulus mu, and shear wave speed c. tausbsp{o}{b} is the remote background loading and phi is the elastodynamic functional representing the effects of spatially non-uniform slip history. An idealized condition of spatially uniform steady state slip leads to a steady state strength curve tausb{strength}=tausb{SS}(V) and a radiation damping line tau=tausbsp{o}{b}-(mu/2c)V. Then a certain range of "under-stressing" is found by requiring that tau≤tausb{strength}, i.e., tausbsp{o}{b}-(mu/2c)V≤tausb{SS}(V), is true for all V. The maximum value of such tausbsp{o}{b} is called tausb{pulse}. An indefinitely expanding crack-like rupture solution does not exist if tausbsp{o}{b}≤tausb{pulse}, implying only the pulse, either growing indefinitely or arresting, can be the solution. For tausbsp{o}{b}>tausb{pulse}, we further classify the rupture patterns based on a parameter T, which should reflect effects of both velocity weakening of the fault and the background loading. First a characteristic dynamic velocity Vsb{dyna} is found as the (larger) velocity solution at which curves tau=tausb{SS}(V) and tau=tausbsp{o}{b}-(mu/2c)V intersect. Then T is quantitatively defined as the slope ratio of these two curves at Vsb{dyna}, i.e., T={-}dtausb{SS}(Vsb{dyna})/dV)/(mu/2c). T=1 at tausbsp{o}{b}=tausb{pulse}, and T decreases with further increase of tausbsp{o}{b}. So T near 1 means tausbsp{o}{b} is close to tausb{pulse} and, numerical simulations with aging laws show that the rupture mode tends to be pulse-like. T near 0 means little continuing velocity weakening at Vsb{dyna}, and simulations show that the apparent rupture mode is crack-like. T near 0.5 is associated with transitional behavior between the crack-like and self-healing modes. If stresses on a natural fault are low on average in the sense discussed here, then they will not allow the crack-like mode, the self-healing slip pulse should be a common phenomenon. Both submodes of it, either growing or decaying with propagation distance, are important mechanisms in adjustment of the stress distribution on the fault surface.

Joint strength of a solid oxide fuel cell glass-ceramic sealant with metallic interconnect in a reducing environment

NASA Astrophysics Data System (ADS)

Lin, Chih-Kuang; Liu, Yu-An; Wu, Si-Han; Liu, Chien-Kuo; Lee, Ruey-Yi

2015-04-01

Effects of reducing environment and thermal aging on the joint strength of a BaO-B2O3-Al2O3-SiO2 glass-ceramic sealant (GC-9) with a ferritic-stainless-steel interconnect (Crofer 22 H) for planar solid oxide fuel cells are investigated. A technique is developed for conducting mechanical tests at room temperature and 800 °C in H2-7 vol% H2O under shear and tensile loadings. Given an aged condition and loading mode, the joint strength at 800 °C is lower than that at room temperature in the given humidified hydrogen atmosphere. A thermal aging at 800 °C in H2-7 vol% H2O for 100 h or 1000 h enhances both shear and tensile joint strengths at room temperature but degrades them at 800 °C in the same reducing environment. Non-aged specimens show a comparable joint strength and fracture mode when tested in humidified hydrogen and in air under a given loading mode and testing temperature. The shear strength at 800 °C for joint specimens after a 1000-h thermal aging at 800 °C in air or humidified hydrogen is reduced by a similar extent of 19%, compared to the counterpart of non-aged joint specimens tested in the same oxidizing or reducing environment.

Comparison between universal adhesives and two-step self-etch adhesives in terms of dentin bond fatigue durability in self-etch mode.

PubMed

Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Watanabe, Hidehiko; Johnson, William W; Latta, Mark A; Miyazaki, Masashi

2017-06-01

This aim of this study was to compare universal adhesives and two-step self-etch adhesives in terms of dentin bond fatigue durability in self-etch mode. Three universal adhesives - Clearfil Universal, G-Premio Bond, and Scotchbond Universal Adhesive - and three-two-step self-etch adhesives - Clearfil SE Bond, Clearfil SE Bond 2, and OptiBond XTR - were used. The initial shear bond strength and shear fatigue strength of resin composite bonded to adhesive on dentin in self-etch mode were determined. Scanning electron microscopy observations of fracture surfaces after bond strength tests were also made. The initial shear bond strength of universal adhesives was material dependent, unlike that of two-step self-etch adhesives. The shear fatigue strength of Scotchbond Universal Adhesive was not significantly different from that of two-step self-etch adhesives, unlike the other universal adhesives. The shear fatigue strength of universal adhesives differed depending on the type of adhesive, unlike those of two-step self-etch adhesives. The results of this study encourage the continued use of two-step self-etch adhesive over some universal adhesives but suggest that changes to the composition of universal adhesives may lead to a dentin bond fatigue durability similar to that of two-step self-etch adhesives. © 2017 Eur J Oral Sci.

A multidimensional anisotropic strength criterion based on Kelvin modes

NASA Astrophysics Data System (ADS)

Arramon, Yves Pierre

A new theory for the prediction of multiaxial strength of anisotropic elastic materials was proposed by Biegler and Mehrabadi (1993). This theory is based on the premise that the total elastic strain energy of an anisotropic material subjected to multiaxial stress can be decomposed into dilatational and deviatoric modes. A multidimensional strength criterion may thus be formulated by postulating that the failure would occur when the energy stored in one of these modes has reached a critical value. However, the logic employed by these authors to formulate a failure criterion based on this theory could not be extended to multiaxial stress. In this thesis, an alternate criterion is presented which redresses the biaxial restriction by reformulating the surfaces of constant modal energy as surfaces of constant eigenstress magnitude. The resulting failure envelope, in a multidimensional stress space, is piecewise smooth. Each facet of the envelope is expected to represent the locus of failure data by a particular Kelvin mode. It is further shown that the Kelvin mode theory alone provides an incomplete description of the failure of some materials, but that this weakness can be addressed by the introduction of a set of complementary modes. A revised theory which combines both Kelvin and complementary modes is thus proposed and applied seven example materials: an isotropic concrete, tetragonal paperboard, two orthotropic softwoods, two orthotropic hardwoods and an orthotropic cortical bone. The resulting failure envelopes for these examples were plotted and, with the exception of concrete, shown to produce intuitively correct failure predictions.

Modified Welding Technique of a Hypo-Eutectic Al-Cu Alloy for Higher Mechanical Properties

NASA Astrophysics Data System (ADS)

Ghosh, B. R.; Gupta, R. K.; Biju, S.; Sinha, P. P.

GTAW process is used for welding of pressure vessels made of hypo-eutectic Al-Cu alloy AA2219 containing 6.3% Cu. As welded Yield strength of the alloy was found to be in the range of 140-150 MPa, using conventional single pass GTAW technique on both AC and DCSP modes. Interestingly, it was also found that weld-strength decreased with increase in thickness of the weld coupons. Welding metallurgy of AA2219 Al alloy was critically reviewed and factors responsible for lower properties were identified. Multipass GTAW on DCSP mode was postulated to improve the weld strength of this alloy. A systematic experimentation using 12 mm thick plates was carried out and YS of 200 MPa has been achieved in the as welded condition. Thorough characterization including optical and electron microscopy was conducted to validate the metallurgical phenomena attributable to improvement in weld strength. This paper presents the conceptual understanding of welding metallurgy of AA2219 alloy and validation by experiments, which could lead to better weld properties using multipass GTAW on DCSP mode.

Magnetorotational instability in protoplanetary discs

NASA Astrophysics Data System (ADS)

Salmeron, Raquel; Wardle, Mark

2005-07-01

We investigate the linear growth and vertical structure of the magnetorotational instability (MRI) in weakly ionized, stratified accretion discs. The magnetic field is initially vertical and dust grains are assumed to have settled towards the mid-plane, so charges are carried by electrons and ions only. Solutions are obtained at representative radial locations from the central protostar for different choices of the initial magnetic field strength, sources of ionization, disc structure and configuration of the conductivity tensor. The MRI is active over a wide range of magnetic field strengths and fluid conditions in low-conductivity discs. Moreover, no evidence was found of a low-limit field strength below which unstable modes do not exist. For the minimum-mass solar nebula model, incorporating cosmic ray ionization, perturbations grow at 1 au for B<~ 8 G. For a significant subset of these strengths (200mG <~B<~ 5G), the maximum growth rate is of the order of the ideal magnetohydrodynamic (MHD) rate (0.75Ω). Hall conductivity modifies the structure and growth rate of global unstable modes at 1 au for all magnetic field strengths that support MRI. As a result, at this radius, modes obtained with a full conductivity tensor grow faster and are active over a more extended cross-section of the disc than perturbations in the ambipolar diffusion limit. For relatively strong fields (e.g. B>~ 200 mG), ambipolar diffusion alters the envelope shapes of the unstable modes, which peak at an intermediate height, instead of being mostly flat as modes in the Hall limit are in this region of parameter space. Similarly, when cosmic rays are assumed to be excluded from the disc by the winds emitted by the magnetically active protostar, unstable modes grow at this radius for B<~ 2 G. For strong fields, perturbations exhibit a kink at the height where X-ray ionization becomes active. Finally, for R= 5 au (10 au), unstable modes exist for B<~ 800 mG (B<~ 250 mG) and the maximum growth rate is close to the ideal-MHD rate for 20 <~B<~ 500 mG (2 <~B<~ 50 mG). Similarly, perturbations incorporating Hall conductivity have a higher wavenumber and grow faster than solutions in the ambipolar diffusion limit for B<~ 100 mG (B<~ 10 mG). Unstable modes grow even at the mid-plane for B>~ 100 mG (B~ 1 mG), but for weaker fields, a small dead region exists. This study shows that, despite the low magnetic coupling, the magnetic field is dynamically important for a large range of fluid conditions and field strengths in protostellar discs. An example of such magnetic activity is the generation of MRI unstable modes, which are supported at 1 au for field strengths up to a few gauss. Hall diffusion largely determines the structure and growth rate of these perturbations for all studied radii. At radii of order 1 au, in particular, it is crucial to incorporate the full conductivity tensor in the analysis of this instability and more generally in studies of the dynamics of astrophysical discs.

Multipoint fiber-optic laser-ultrasonic actuator based on fiber core-opened tapers.

PubMed

Tian, Jiajun; Dong, Xiaolong; Gao, Shimin; Yao, Yong

2017-11-27

In this study, a novel fiber-optic, multipoint, laser-ultrasonic actuator based on fiber core-opened tapers (COTs) is proposed and demonstrated. The COTs were fabricated by splicing single-mode fibers using a standard fiber splicer. A COT can effectively couple part of a core mode into cladding modes, and the coupling ratio can be controlled by adjusting the taper length. Such characteristics are used to obtain a multipoint, laser-ultrasonic actuator with balanced signal strength by reasonably controlling the taper lengths of the COTs. As a prototype, we constructed an actuator that generated ultrasound at four points with a balanced ultrasonic strength by connecting four COTs with coupling ratios of 24.5%, 33.01%, 49.51%, and 87.8% in a fiber link. This simple-to-fabricate, multipoint, laser-ultrasonic actuator with balanced ultrasound signal strength has potential applications in fiber-optic ultrasound testing technology.

A New Rock Strength Criterion from Microcracking Mechanisms Which Provides Theoretical Evidence of Hybrid Failure

NASA Astrophysics Data System (ADS)

Zhu, Qi-Zhi

2017-02-01

A proper criterion describing when material fails is essential for deep understanding and constitutive modeling of rock damage and failure by microcracking. Physically, such a criterion should be the global effect of local mechanical response and microstructure evolution inside the material. This paper aims at deriving a new mechanisms-based failure criterion for brittle rocks, based on micromechanical unilateral damage-friction coupling analyses rather than on the basic results from the classical linear elastic fracture mechanics. The failure functions respectively describing three failure modes (purely tensile mode, tensile-shear mode as well as compressive-shear mode) are achieved in a unified upscaling framework and illustrated in the Mohr plane and also in the plane of principal stresses. The strength envelope is proved to be continuous and smooth with a compressive to tensile strength ratio dependent on material properties. Comparisons with experimental data are finally carried out. By this work, we also provide a theoretical evidence on the hybrid failure and the smooth transition from tensile failure to compressive-shear failure.

Observation of the inductive to helicon mode transition in a weakly magnetized solenoidal inductive discharge

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

Lee, Min-Hyong; Chung, Chin-Wook

2008-10-13

A mode transition from an inductive mode to a helicon mode is observed in a solenoidal inductive discharge immersed in a weak dc magnetic field. The measured electron temperature and the plasma density at the reactor radial boundary show a sudden increase when the magnetic field strength reaches the critical value and the electron cyclotron frequency exceeds the rf driving frequency. These increases are due to the electron heating by the helicon wave. Such increases in the temperature and the density are not observed at the plasma center because the helicon wave cannot propagate to the center of the solenoidalmore » type reactor unless the magnetic field is very high. These results show that the transition of the discharge from the inductive to the helicon mode occurs at the critical magnetic field strength.« less

"Scissors, Paper, Stone": Perceptual Foundations of Noun Classifier Systems.

ERIC Educational Resources Information Center

Erbaugh, Mary S.

While all languages use shape to classify unfamiliar objects, some languages as diverse as Mandarin, Thai, Japanese, Mohawk, and American Sign Language lexicalize these and other types of description as noun classifiers. Classification does not develop from a fixed set of features in the object, but is discourse-sensitive and invoked when it would…

A Second Life for CDs

ERIC Educational Resources Information Center

Snoderly, Kathleen

2011-01-01

Cutting a few CDs apart with scissors, the author found that the process created somewhat brittle shards. As a result, she started to paint a few with acrylic, finding to her amazement that the paint gave the CDs a leathery, more manageable texture. Upon further experimentation, she found that if the CDs are painted somewhat translucently in…

SUBVERISON: Uruguayan Armed Forces Summary of Subversive Movement in Latin America. Part I

DTIC Science & Technology

1977-08-12

nication" ("Problemas y Perspectivas de la Comunicacion de Masas"), Buenos Aires, TROQUEL. 935 ARGENTINA. Leonard C. Lewin, "Undesirable Peace...and the Scissors. The Means of Social Communication in Argentina" ("La Red y La Tijera. Los Medios de Comunicacion Social en la Argentina

Losers in the 'Rock-Paper-Scissors' game: The role of non-hierarchical competition and chaos as biodiversity sustaining agents in aquatic systems

EPA Science Inventory

Processes occurring within small areas (patch-scale) that influence species richness and spatial heterogeneity of larger areas (landscape-scale) have long been an interest of ecologists. This research focused on the role of patch-scale deterministic chaos arising in phytoplankton...

Five Easy Principles to Make Math Moments Count

ERIC Educational Resources Information Center

Cutler, Carrie S.

2011-01-01

Preschool children are learning so many skills--how to cut with scissors, zip zippers, recognize the alphabet and their names, and share toys with others. A strong academic curriculum also requires that children learn more about math (National Council of Teachers of Mathematics [NCTM], 2000). By following the five easy principles outlined here,…

Volunteering leads to rock-paper-scissors dynamics in a public goods game

NASA Astrophysics Data System (ADS)

Semmann, Dirk; Krambeck, Hans-Jürgen; Milinski, Manfred

2003-09-01

Collective efforts are a trademark of both insect and human societies. They are achieved through relatedness in the former and unknown mechanisms in the latter. The problem of achieving cooperation among non-kin has been described as the `tragedy of the commons', prophesying the inescapable collapse of many human enterprises. In public goods experiments, initial cooperation usually drops quickly to almost zero. It can be maintained by the opportunity to punish defectors or the need to maintain good reputation. Both schemes require that defectors are identified. Theorists propose that a simple but effective mechanism operates under full anonymity. With optional participation in the public goods game, `loners' (players who do not join the group), defectors and cooperators will coexist through rock-paper-scissors dynamics. Here we show experimentally that volunteering generates these dynamics in public goods games and that manipulating initial conditions can produce each predicted direction. If, by manipulating displayed decisions, it is pretended that defectors have the highest frequency, loners soon become most frequent, as do cooperators after loners and defectors after cooperators. On average, cooperation is perpetuated at a substantial level.

Concurrent performance in a three-alternative choice situation: response allocation in a Rock/Paper/Scissors game.

PubMed

Kangas, Brian D; Berry, Meredith S; Cassidy, Rachel N; Dallery, Jesse; Vaidya, Manish; Hackenberg, Timothy D

2009-10-01

Adult human subjects engaged in a simulated Rock/Paper/Scissors game against a computer opponent. The computer opponent's responses were determined by programmed probabilities that differed across 10 blocks of 100 trials each. Response allocation in Experiment 1 was well described by a modified version of the generalized matching equation, with undermatching observed in all subjects. To assess the effects of instructions on response allocation, accurate probability-related information on how the computer was programmed to respond was provided to subjects in Experiment 2. Five of 6 subjects played the counter response of the computer's dominant programmed response near-exclusively (e.g., subjects played paper almost exclusively if the probability of rock was high), resulting in minor overmatching, and higher reinforcement rates relative to Experiment 1. On the whole, the study shows that the generalized matching law provides a good description of complex human choice in a gaming context, and illustrates a promising set of laboratory methods and analytic techniques that capture important features of human choice outside the laboratory.

Stump closure of a thick pancreas using stapler closure increases pancreatic fistula after distal pancreatectomy.

PubMed

Kawai, Manabu; Tani, Masaji; Okada, Ken-ichi; Hirono, Seiko; Miyazawa, Motoki; Shimizu, Astusi; Kitahata, Yuji; Yamaue, Hiroki

2013-09-01

The appropriate surgical stump closure after distal pancreatectomy (DP) is still controversial. This study investigated the benefits and risks of stapler closure during DP. The risk factors of pancreatic fistulas were investigated in 122 DPs among 3 types of stump closure: hand-sewn suture (n = 32), bipolar scissors (n = 45), and stapler closure (n = 45). There was no significant difference in the incidence of pancreatic fistula between the 3 types of stump closure (hand-sewn suture [44%] vs bipolar scissors [37.7%] vs stapler closure [35.5%]). By using receiver operating characteristics curves, 12 mm was the best cutoff value of the thickness of the pancreas for pancreatic fistulas after DP using stapler closure. Three factors (ie, male sex, body mass index >25 kg/m(2), and stapler closure) were independent risk factors of pancreatic fistulas after DP with a pancreas thicker than 12 mm. A pancreas thicker than 12 mm significantly increased the incidence of pancreatic fistulas after DP using stapler closure. Copyright © 2013 Elsevier Inc. All rights reserved.

Oscillatory dynamics in rock-paper-scissors games with mutations.

PubMed

Mobilia, Mauro

2010-05-07

We study the oscillatory dynamics in the generic three-species rock-paper-scissors games with mutations. In the mean-field limit, different behaviors are found: (a) for high mutation rate, there is a stable interior fixed point with coexistence of all species; (b) for low mutation rates, there is a region of the parameter space characterized by a limit cycle resulting from a Hopf bifurcation; (c) in the absence of mutations, there is a region where heteroclinic cycles yield oscillations of large amplitude (not robust against noise). After a discussion on the main properties of the mean-field dynamics, we investigate the stochastic version of the model within an individual-based formulation. Demographic fluctuations are therefore naturally accounted and their effects are studied using a diffusion theory complemented by numerical simulations. It is thus shown that persistent erratic oscillations (quasi-cycles) of large amplitude emerge from a noise-induced resonance phenomenon. We also analytically and numerically compute the average escape time necessary to reach a (quasi-)cycle on which the system oscillates at a given amplitude. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Social cycling and conditional responses in the Rock-Paper-Scissors game

PubMed Central

Wang, Zhijian; Xu, Bin; Zhou, Hai-Jun

2014-01-01

How humans make decisions in non-cooperative strategic interactions is a big question. For the fundamental Rock-Paper-Scissors (RPS) model game system, classic Nash equilibrium (NE) theory predicts that players randomize completely their action choices to avoid being exploited, while evolutionary game theory of bounded rationality in general predicts persistent cyclic motions, especially in finite populations. However as empirical studies have been relatively sparse, it is still a controversial issue as to which theoretical framework is more appropriate to describe decision-making of human subjects. Here we observe population-level persistent cyclic motions in a laboratory experiment of the discrete-time iterated RPS game under the traditional random pairwise-matching protocol. This collective behavior contradicts with the NE theory but is quantitatively explained, without any adjustable parameter, by a microscopic model of win-lose-tie conditional response. Theoretical calculations suggest that if all players adopt the same optimized conditional response strategy, their accumulated payoff will be much higher than the reference value of the NE mixed strategy. Our work demonstrates the feasibility of understanding human competition behaviors from the angle of non-equilibrium statistical physics. PMID:25060115

Effect of curing modes of dual-curing core systems on microtensile bond strength to dentin and formation of an acid-base resistant zone.

PubMed

Li, Na; Takagaki, Tomohiro; Sadr, Alireza; Waidyasekera, Kanchana; Ikeda, Masaomi; Chen, Jihua; Nikaido, Toru; Tagami, Junji

2011-12-01

To evaluate the microtensile bond strength (μTBS) and acid-base resistant zone (ABRZ) of two dualcuring core systems to dentin using four curing modes. Sixty-four caries-free human molars were randomly divided into two groups according to two dual-curing resin core systems: (1) Clearfil DC Core Automix; (2) Estelite Core Quick. For each core system, four different curing modes were applied to the adhesive and core resin: (1) dual-cured and dual-cured (DD); (2) chemically cured and dual-cured (CD); (3) dual-cured and chemically cured (DC); (4) chemically cured and chemically cured (CC). The specimens were sectioned into sticks (n = 20 for each group) for the microtensile bond test. μTBS data were analyzed using two-way ANOVA and the Dunnett T3 test. Failure patterns were examined with scanning electron microscopy (SEM) to determine the proportion of each mode. Dentin sandwiches were produced and subjected to an acid-base challenge. After argon-ion etching, the ultrastructure of ABRZ was observed using SEM. For Clearfil DC Core Automix, the μTBS values in MPa were as follows: DD: 29.1 ± 5.4, CD: 21.6 ± 5.6, DC: 17.9 ± 2.8, CC: 11.5 ± 3.2. For Estelite Core Quick, they were: DD: 48.9 ±5.7, CD: 20.5 ± 4.7, DC: 41.4 ± 8.3, CC: 19.1 ± 6.0. The bond strength was affected by both material and curing mode, and the interaction of the two factors was significant (p < 0.001). Within both systems, there were significant differences among groups, and the DD group showed the highest μTBS (p < 0.05). ABRZ morphology was not affected by curing mode, but it was highly adhesive-material dependent. The curing mode of dual-curing core systems affects bond strength to dentin, but has no significant effect on the formation of ABRZ.

Experience of the fibrotest for measuring cotton fiber length and strength properties

USDA-ARS?s Scientific Manuscript database

The Fibrotest is a device developed by Textechno for measuring cotton fiber length and strength properties. The Fibrotest provides abundant information, including more than 20 length and strength parameters in absolute and relative modes, and displays fibrogram, load-elongation curve, and fiber bea...

Effect of sonic application mode on the resin-dentin bond strength and dentin permeability of self-etching systems.

PubMed

Mena-Serrano, Alexandra; Costa, Thays Regina Ferreira da; Patzlaff, Rafael Tiago; Loguercio, Alessandro Dourado; Reis, Alessandra

2014-10-01

To compare manual and sonic adhesive application modes in terms of the permeability and microtensile bond strength of a self-etching adhesive applied in the one-step or two-step protocol. Self-etching All Bond SE (Bisco) was applied as a one- or a two-step adhesive under manual or sonic vibration modes on flat occlusal dentin surfaces of 64 human molars. Half of the teeth were used to measure the hydraulic conductance of dentin at 200 cm H₂O hydrostatic pressure for 5 min immediately after the adhesive application. In the other half, composite buildups (Opallis) were constructed incrementally to create resin-dentin sticks with a cross-sectional area of 0.8 mm² to be tested in tension (0.5 mm/min) immediately after restoration placement. Data were analyzed using a two-way ANOVA and Tukey's test (α = 0.05). The fluid conductance of dentin was significantly reduced by the sonic vibration mode for both adhesives, but no effect on the bond strength values was observed for either adhesive. The sonic application mode at an oscillating frequency of 170 Hz can reduce the fluid conductance of the one- and two-step All Bond SE adhesive when applied on dentin.

Compression of thick laminated composite beams with initial impact-like damage

NASA Technical Reports Server (NTRS)

Breivik, N. L.; Guerdal, Z.; Griffin, O. H., Jr.

1992-01-01

While the study of compression after impact of laminated composites has been under consideration for many years, the complexity of the damage initiated by low velocity impact has not lent itself to simple predictive models for compression strength. The damage modes due to non-penetrating, low velocity impact by large diameter objects can be simulated using quasi-static three-point bending. The resulting damage modes are less coupled and more easily characterized than actual impact damage modes. This study includes the compression testing of specimens with well documented initial damage states obtained from three-point bend testing. Compression strengths and failure modes were obtained for quasi-isotropic stacking sequences from 0.24 to 1.1 inches thick with both grouped and interspersed ply stacking. Initial damage prior to compression testing was divided into four classifications based on the type, extent, and location of the damage. These classifications are multiple through-thickness delaminations, isolated delamination, damage near the surface, and matrix cracks. Specimens from each classification were compared to specimens tested without initial damage in order to determine the effects of the initial damage on the final compression strength and failure modes. A finite element analysis was used to aid in the understanding and explanation of the experimental results.

The Effect of Food-Simulating Agents on the Bond Strength of Hard Chairside Reline Materials to Denture Base Resin.

PubMed

Fatemi, Farzaneh Sadat; Vojdani, Mahroo; Khaledi, Amir Ali Reza

2018-06-08

To investigate the influence of food-simulating agents on the shear bond strength between direct hard liners and denture base acrylic resin. In addition, mode of failure was evaluated. One hundred fifty cylindrical columns of denture base resin were fabricated and bonded to three types of hard reline materials (Hard GC Reline, Tokuyama Rebase II Fast, TDV Cold Liner Rebase). Specimens of each reline material were divided into five groups (n = 10) to undergo 12-day immersion in distilled water, 0.02 N citric acid aqueous solution, heptane, and 40% ethanol/water solution at 37°C. The control group was not immersed in any solution. The shear bond strength test was performed, and the failure mode was determined. Statistics were analyzed with two-way ANOVA and chi-square test (α = 0.05). Significant interaction was found between the hard liners and food simulating agents (p < 0.001). The shear bond strength of Tokuyama in 40% ethanol and TDV in heptane decreased significantly (p = 0.001, p < 0.001 respectively); however, none of the solutions could significantly affect the shear bond strength of Hard GC Reline (p = 0.208). The mixed failure mode occurred more frequently in Hard GC Reline compared with the other liners (p < 0.001) and was predominant in specimens with higher bond strength values (p = 0.012). Food simulating agents did not adversely affect the shear bond strength of Hard GC Reline; however, ethanol and heptane decreased the bond strength of Tokuyama and TDV, respectively. These findings may provide support to dentists to recommend restricted consumption of some foods and beverages for patients who have to use dentures relined with certain hard liners. © 2018 by the American College of Prosthodontists.

Dentin pretreatment and adhesive temperature as affecting factors on bond strength of a universal adhesive system.

PubMed

Sutil, Bruna Gabrielle da Silva; Susin, Alexandre Henrique

2017-01-01

To evaluate the effects of dentin pretreatment and temperature on the bond strength of a universal adhesive system to dentin. Ninety-six extracted non-carious human third molars were randomly divided into 12 groups (n=8) according to Scotchbond Universal Adhesive (SbU) applied in self-etch (SE) and etch-and-rinse (ER) mode, adhesive temperature (20°C or 37°C) and sodium bicarbonate or aluminum oxide air abrasion. After composite build up, bonded sticks with cross-sectional area of 1 mm2 were obtained to evaluate the microtensile bond strength (μTBS). The specimens were tested at a crosshead speed of 0.5 mm/min on a testing machine until failure. Fractured specimens were analyzed under stereomicroscope to determine the failure patterns in adhesive, cohesive (dentin or resin) and mixed fractures. The microtensile bond strength data was analyzed using two-way ANOVA and Tukey's test (α=5%). Interaction between treatment and temperature was statistically significant for SbU applied in self-etch technique. Both dentin treatments showed higher bond strength for ER mode, regardless of adhesive temperature. When compared to control group, sodium bicarbonate increased bond strength of SbU in SE technique. Adhesive temperature did not significantly affect the μTBS of tested groups. Predominantly, adhesive failure was observed for all groups. Dentin surface treatment with sodium bicarbonate air abrasion improves bond strength of SbU, irrespective of adhesive application mode, which makes this approach an alternative to increase adhesive performance of Scotchbond Universal Adhesive to dentin.

Dentin pretreatment and adhesive temperature as affecting factors on bond strength of a universal adhesive system

PubMed Central

Sutil, Bruna Gabrielle da Silva; Susin, Alexandre Henrique

2017-01-01

Abstract Objectives: To evaluate the effects of dentin pretreatment and temperature on the bond strength of a universal adhesive system to dentin. Material and Methods: Ninety-six extracted non-carious human third molars were randomly divided into 12 groups (n=8) according to Scotchbond Universal Adhesive (SbU) applied in self-etch (SE) and etch-and-rinse (ER) mode, adhesive temperature (20°C or 37°C) and sodium bicarbonate or aluminum oxide air abrasion. After composite build up, bonded sticks with cross-sectional area of 1 mm2 were obtained to evaluate the microtensile bond strength (μTBS). The specimens were tested at a crosshead speed of 0.5 mm/min on a testing machine until failure. Fractured specimens were analyzed under stereomicroscope to determine the failure patterns in adhesive, cohesive (dentin or resin) and mixed fractures. The microtensile bond strength data was analyzed using two-way ANOVA and Tukey's test (α=5%). Results: Interaction between treatment and temperature was statistically significant for SbU applied in self-etch technique. Both dentin treatments showed higher bond strength for ER mode, regardless of adhesive temperature. When compared to control group, sodium bicarbonate increased bond strength of SbU in SE technique. Adhesive temperature did not significantly affect the μTBS of tested groups. Predominantly, adhesive failure was observed for all groups. Conclusions: Dentin surface treatment with sodium bicarbonate air abrasion improves bond strength of SbU, irrespective of adhesive application mode, which makes this approach an alternative to increase adhesive performance of Scotchbond Universal Adhesive to dentin. PMID:29069151

Multi-mode radio frequency device

DOEpatents

Gilbert, Ronald W [Morgan Hill, CA; Carrender, Curtis Lee [Morgan Hill, CA; Anderson, Gordon A [Benton City, WA; Steele, Kerry D [Kennewick, WA

2007-02-13

A transponder device having multiple modes of operation, such as an active mode and a passive mode, wherein the modes of operation are selected in response to the strength of a received radio frequency signal. A communication system is also provided having a transceiver configured to transmit a radio frequency signal and to receive a responsive signal, and a transponder configured to operate in a plurality of modes and to activate modes of operation in response to the radio frequency signal. Ideally, each mode of operation is activated and deactivated independent of the other modes, although two or more modes may be concurrently operational.

Sentiment Diffusion of Public Opinions about Hot Events: Based on Complex Network

PubMed Central

Hao, Xiaoqing; An, Haizhong; Zhang, Lijia; Li, Huajiao; Wei, Guannan

2015-01-01

To study the sentiment diffusion of online public opinions about hot events, we collected people’s posts through web data mining techniques. We calculated the sentiment value of each post based on a sentiment dictionary. Next, we divided those posts into five different orientations of sentiments: strongly positive (P), weakly positive (p), neutral (o), weakly negative (n), and strongly negative (N). These sentiments are combined into modes through coarse graining. We constructed sentiment mode complex network of online public opinions (SMCOP) with modes as nodes and the conversion relation in chronological order between different types of modes as edges. We calculated the strength, k-plex clique, clustering coefficient and betweenness centrality of the SMCOP. The results show that the strength distribution obeys power law. Most posts’ sentiments are weakly positive and neutral, whereas few are strongly negative. There are weakly positive subgroups and neutral subgroups with ppppp and ooooo as the core mode, respectively. Few modes have larger betweenness centrality values and most modes convert to each other with these higher betweenness centrality modes as mediums. Therefore, the relevant person or institutes can take measures to lead people’s sentiments regarding online hot events according to the sentiment diffusion mechanism. PMID:26462230

Comparison of Three Methods of Assessing Muscle Strength and Imbalance Ratios of the Knee

PubMed Central

Moss, Crayton L.; Wright, P. Thomas

1993-01-01

Three strength measurement methods for determining muscle strength and imbalance ratios of the knee were compared in 41 (23 female, 18 male) NCAA Division I track and field athletes. Peak quadriceps extensions and hamstring flexions were measured isotonically, isometrically, and isokinetically. Isokinetic measurements were performed on a Cybex II at 60°/s. Isometric extension and flexion measurements were performed using the Nicholas Manual Muscle Tester (Lafayette Instruments; Lafayette, Ind). Isotonic measurements were done on both Universal and Nautilus apparatuses. Testing order was randomized to avoid a treatment order effect. A repeated measures ANOVA and a post hoc Tukey test were used to compare the three methods of assessing strength and imbalance ratios of the knee. Absolute strength values were significantly different according to gender and mode of testing. Bilateral strength imbalance ratios for knee flexion were significantly lower for the Nautilus leg curl machine. Ipsilateral strength imbalance ratios were significantly greater for the Cybex II. Our results indicated that absolute strength values cannot be interchanged between testing modes. Except for Cybex II (ipsilateral) and Nautilus (bilateral knee flexion), strength imbalance ratios could be interchanged. ImagesFig 1.Fig 2.Fig 3.Fig 4.Fig 5.Fig 6.Fig 7.INGING PMID:16558207

True Triaxial Strength and Failure Modes of Cubic Rock Specimens with Unloading the Minor Principal Stress

NASA Astrophysics Data System (ADS)

Li, Xibing; Du, Kun; Li, Diyuan

2015-11-01

True triaxial tests have been carried out on granite, sandstone and cement mortar using cubic specimens with the process of unloading the minor principal stress. The strengths and failure modes of the three rock materials are studied in the processes of unloading σ 3 and loading σ 1 by the newly developed true triaxial test system under different σ 2, aiming to study the mechanical responses of the rock in underground excavation at depth. It shows that the rock strength increases with the raising of the intermediate principal stress σ 2 when σ 3 is unloaded to zero. The true triaxial strength criterion by the power-law relationship can be used to fit the testing data. The "best-fitting" material parameters A and n ( A > 1.4 and n < 1.0) are almost located in the same range as expected by Al-Ajmi and Zimmerman (Int J Rock Mech Min Sci 563 42(3):431-439, 2005). It indicates that the end effect caused by the height-to-width ratio of the cubic specimens will not significantly affect the testing results under true triaxial tests. Both the strength and failure modes of cubic rock specimens under true triaxial unloading condition are affected by the intermediate principal stress. When σ 2 increases to a critical value for the strong and hard rocks (R4, R5 and R6), the rock failure mode may change from shear to slabbing. However, for medium strong and weak rocks (R3 and R2), even with a relatively high intermediate principal stress, they tend to fail in shear after a large amount of plastic deformation. The maximum extension strain criterion Stacey (Int J Rock Mech Min Sci Geomech Abstr 651 18(6):469-474, 1981) can be used to explain the change of failure mode from shear to slabbing for strong and hard rocks under true triaxial unloading test condition.

Fatigue of notched fiber composite laminates. Part 2: Analytical and experimental evaluation

NASA Technical Reports Server (NTRS)

Kulkarni, S. V.; Mclaughlin, P. V., Jr.; Pipes, R. B.

1976-01-01

The analytical/experimental correlation study was performed to develop an understanding of the behavior of notched Boron/epoxy laminates subjected to tension/tension fatigue loading. It is postulated that the fatigue induced property changes (stiffness as well as strength) of the laminate can be obtained from the lamina fatigue properties. To that end, the Boron/epoxy lamina static and fatigue data (lifetime, residual stiffness and strength) were obtained initially. The longitudinal and transverse tension data were determined from the (0) and (90) laminate tests while the in-plane shear data were obtained from the (+ or - 45) sub s laminates. The static tests obtained the notched strength and mode of failure while the fatigue tests determined lifetime, damage propagation and residual strength. The failure in static tension occurred in a transverse crack propagation mode.

Application and Prospects of High-strength Lightweight Materials used in Coal mine

NASA Astrophysics Data System (ADS)

He, Pan

2017-09-01

This paper describes some high-strength lightweight materials used in coal mine, and if their performance can meet the requirements of underground safety for explosion-proof, anti-static, friction sparks mine; and reviewed the species, characteristic, preparation process of high-strength lightweight materials for having inspired lightweight high-strength performance by modifying or changing the synthesis mode used in coal mine equipment.

Protein unfolding versus β-sheet separation in spider silk nanocrystals

NASA Astrophysics Data System (ADS)

Alam, Parvez

2014-03-01

In this communication a mechanism for spider silk strain hardening is proposed. Shear failure of β-sheet nanocrystals is the first failure mode that gives rise to the creation of smaller nanocrystals, which are of higher strength and stiffness. β-sheet unfolding requires more energy than nanocrystal separation in a shear mode of failure. As a result, unfolding occurs after the nanocrystals separate in shear. β-sheet unfolding yields a secondary strain hardening effect once the β-sheet conformation is geometrically stable and acts like a unidirectional fibre in a fibre reinforced composite. The mechanism suggested herein is based on molecular dynamics calculations of residual inter-β-sheet separation strengths against residual intra-β-sheet unfolding strengths.

No Scissors Allowed

ERIC Educational Resources Information Center

Bates, Janet

2012-01-01

Once, in the author's continual quest for unique and varied art projects, she was inspired by a colorful Kleenex[R] box which was covered with faces in a variety of sizes, ages, shapes and colors. What a fun idea to have her class create their own portraits using only construction paper, glue and one's fingers. As she shared an examplar rip-art…

Paper, Scissors, Rock: Aspects of the Intertwined Histories of Pedagogy and Model-Making

ERIC Educational Resources Information Center

Insley, Jane

2017-01-01

Investigating the stories behind the makers of 3D models of crystals has proved unexpectedly unstraightforward. Drawing on actor-network theory (ANT), this article investigates the references behind a set of models of mineralogical crystals made of pasteboard held by National Museums Scotland (NMS), to uncover the history and tradition of such…

Compact, Low-Power, and High-Speed Graphene-Based Integrated Photonic Modulator Technology

DTIC Science & Technology

2017-11-02

which we want to transfer graphene, we cut the graphene-on- Copper foil into appropriate pieces using sharp razor blades or scissors. We then follow a...rinsed under running DI water for 5 minutes. Patterns on HSQ are then transferred to alumina in a Plasma-Therm ICP system using the recipe which was

The Use of Tools by Children with Hemophilia.

ERIC Educational Resources Information Center

Markova, I.; And Others

1984-01-01

Eight mothers with their 3.1- to 5.7-year-old hemophiliac children and eight control mothers with their nonhemophiliac children were videotaped while playing two games without tools and three additional games involving use of a knife, a pair of scissors, and a wooden hammer. Mothers of hemophiliac children did not correct their children when they…

Demonstration of the Principles of Restriction Endonuclease Cleavage Reactions Using Thermostable Bfl I from "Anoxybacillus Flavithermus"

ERIC Educational Resources Information Center

Sharma, Prince; D'Souza, David R.; Bhandari, Deepali; Parashar, Vijay; Capalash, Neena

2003-01-01

Restriction enzymes are basic tools in recombinant DNA technology. To shape the molecular biology experiments, the students must know how to work with these molecular scissors. Here, we describe an integrated set of experiments, introduced in the "Advances in Molecular Biology and Biotechnology" postgraduate course, which covers the important…

Rockin' around the Rock Cycle

ERIC Educational Resources Information Center

Frack, Susan; Blanchard, Scott Alan

2005-01-01

In this activity students will simulate how sedimentary rocks can be changed into metamorphic rocks by intense pressure. The materials needed are two small pieces of white bread, one piece of wheat bread, and one piece of a dark bread (such as pumpernickel or dark rye) per student, two pieces of waxed paper, scissors, a ruler, and heavy books.…

Effect of universal adhesive etching modes on bond strength to dual-polymerizing composite resins.

PubMed

Michaud, Pierre-Luc; Brown, Matthew

2018-04-01

Information is lacking as to the effect on bond strength of the etching modes of universal adhesives when they are used to bond dual-polymerizing composite resins to dentin. The purpose of this in vitro study was to investigate the bonding of dual-polymerizing foundation composite resins to dentin when universal bonding agents are used in self-etch or etch-and-rinse modes. Sixty caries-free, extracted third molar teeth were sectioned transversely in the apical third of the crown and allocated to 12 groups (n=5). Three different bonding agents (Scotchbond Universal, OptiBond XTR, All-Bond Universal) were used to bond 2 different dual-polymerizing composite resins (CompCore AF or CoreFlo DC) to dentin, using 2 different etching approaches (etch-and-rinse or self-etch). The specimens were sectioned into sticks (1×1×8 mm) with a precision saw. The bond strength of the specimens was tested under microtensile force at a crosshead speed of 0.5 mm/min. The data were analyzed using a 3-way ANOVA, a Games-Howell post hoc comparisons model, and Student t tests with Bonferroni corrections (α=.05). In the overall model, the composite resin used had no effect on bond strength (P=.830). The etching protocol by itself also did not have a significant effect (P=.059), although a trend was present. The bonding agent, however, did have an effect (P<.001) on bond strength. Also, a significant interaction effect was found for the bonding agent and etching protocol on bond strength (P<.001). The etching protocol influenced the bond strength when Scotchbond Universal (P<.008) and All-Bond Universal (P<.004) were used but not when OptiBond XTR was used (P=1.00). A self-etch protocol provided significantly higher bond strength when Scotchbond Universal was used, whereas with All-Bond Universal, an etch-and-rinse protocol, provided higher bond strength. When universal bonding agents were used to secure dual-polymerizing composite resins to dentin, no single etching protocol is better than another. Depending on which bonding agent is being used, one etching mode may perform better. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Driven acoustic oscillations within a vertical magnetic field

NASA Technical Reports Server (NTRS)

Hindman, Bradley W.; Zweibel, Ellen G.; Cally, P. S.

1995-01-01

The effects of a vertical magnetic field on p-mode frequencies, line widths, and eigenfunctions, are examined. A solar model, consisting of a neutrally stable polytropic interior matched to an isothermal chromosphere, is applied. The p-modes are produced by a spatially distributed driver. The atmosphere is threaded by a constant vertical magnetic field. The frequency shifts due to the vertical magnetic field are found to be much smaller than the shifts caused by horizontal fields of similar strength. A large vertical field of 2000 G produces shifts of several nHz. It is found that the frequency shifts decrease with increasing frequency and increase with field strength. The coupling of the acoustic fast mode to the escaping slow modes is inefficient. Constant vertical magnetic field models are therefore incapable of explaining the high level of absorption observed in sunspots and plage.

Comparison of Strength Gains in Untrained College-Age Females Using Free Weights and Freemotion Machines

ERIC Educational Resources Information Center

Milton, Katherine; Wojcik, Janet R.; Boyd, Joni M.; Bowers, Charles J.

2018-01-01

Resistance training has become a preferred method for developing muscular strength among various populations. A variety of resistance training modes are available, but there are mixed outcomes regarding strength development among barbells, dumbbells, and weight machines. The purpose of this study was to investigate the differences in strength…

The Influence of GI and GII on the Compression After Impact Strength of Carbon Fiber/Epoxy Laminates and Sandwich Structure

NASA Technical Reports Server (NTRS)

Nettles, A. T.; Scharber, L. L.

2017-01-01

This study measured the compression after impact strength of IM7 carbon fiber laminates made from epoxy resins with various mode I and mode II toughness values to observe the effects of these toughness values on the resistance to damage formation and subsequent residual compression strength-carrying capabilities. Both monolithic laminates and sandwich structure were evaluated. A total of seven different epoxy resin systems were used ranging in approximate GI values of 245-665 J/sq m and approximate GII values of 840-2275 J/sq m. The results for resistance to impact damage formation showed that there was a direct correlation between GII and the planar size of damage, as measured by thermography. Subsequent residual compression strength testing suggested that GI had no influence on the measured values and most of the difference in compression strength was directly related to the size of damage. Thus, delamination growth assumed as an opening type of failure mechanism does not appear to be responsible for loss of compression strength in the specimens examined in this study.

Mechanical properties of resin cements with different activation modes.

PubMed

Braga, R R; Cesar, P F; Gonzaga, C C

2002-03-01

Dual-cured cements have been studied in terms of the hardness or degree of conversion achieved with different curing modes. However, little emphasis is given to the influence of the curing method on other mechanical properties. This study investigated the flexural strength, flexural modulus and hardness of four proprietary resin cements. Materials tested were: Enforce and Variolink II (light-, self- and dual-cured), RelyX ARC (self- and dual-cured) and C & B (self-cured). Specimens were fractured using a three-point bending test. Pre-failure loads corresponding to specific displacements of the cross-head were used for flexural modulus calculation. Knoop hardness (KHN) was measured on fragments obtained after the flexural test. Tests were performed after 24 h storage at 37 degrees C. RelyX ARC dual-cured showed higher flexural strength than the other groups. RelyX ARC and Variolink II depended upon photo-activation to achieve higher hardness values. Enforce showed similar hardness for dual- and self-curing modes. No correlation was found between flexural strength and hardness, indicating that other factors besides the degree of cure (e.g. filler content and monomer type) affect the flexural strength of composites. No statistical difference was detected in the flexural modulus among the different groups.

Effect of framework design on crown failure.

PubMed

Bonfante, Estevam A; da Silva, Nelson R F A; Coelho, Paulo G; Bayardo-González, Daniel E; Thompson, Van P; Bonfante, Gerson

2009-04-01

This study evaluated the effect of core-design modification on the characteristic strength and failure modes of glass-infiltrated alumina (In-Ceram) (ICA) compared with porcelain fused to metal (PFM). Premolar crowns of a standard design (PFMs and ICAs) or with a modified framework design (PFMm and ICAm) were fabricated, cemented on dies, and loaded until failure. The crowns were loaded at 0.5 mm min(-1) using a 6.25 mm tungsten-carbide ball at the central fossa. Fracture load values were recorded and fracture analysis of representative samples were evaluated using scanning electron microscopy. Probability Weibull curves with two-sided 90% confidence limits were calculated for each group and a contour plot of the characteristic strength was obtained. Design modification showed an increase in the characteristic strength of the PFMm and ICAm groups, with PFM groups showing higher characteristic strength than ICA groups. The PFMm group showed the highest characteristic strength among all groups. Fracture modes of PFMs and of PFMm frequently reached the core interface at the lingual cusp, whereas ICA exhibited bulk fracture through the alumina core. Core-design modification significantly improved the characteristic strength for PFM and for ICA. The PFM groups demonstrated higher characteristic strength than both ICA groups combined.

High temperature compounds for turbine vanes. [of SiC, Si3N4, and Si composites

NASA Technical Reports Server (NTRS)

Rhodes, W. H.; Cannon, R. M., Jr.

1974-01-01

Fabrication and microstructure control studies were conducted on SiC, Si3N and composites based on Si3N. Charpy mode impact testing to 2400 F established that Si3N4/Mo composites have excellent potential. Attempts to fabricate composites of Si3N4 with superalloys, both by hot pressing and infiltration were largely unsuccessful in comparison to using Mo, Re, and Ta which are less reactive. Modest improvements in impact strength were realized for monolithic Si3N4; however, SiC strengths increased by a factor of six and now equal values achieved for Si3N4. Correlations of impact strength with material properties are discussed. Reduced MgO densification aid additions to Si3N4 were found to decrease densification kinetics, increase final porosity, decrease room temperature bend strength, increase high temperature bend strength, and decrease bend stress rupture properties. The decrease in bend strength at high temperature for fine grain size SiC suggested that a slightly larger grain size material with a nearly constant strength-temperature relation may prove desirable in the creep and stress rupture mode.

Large-scale brain network coupling predicts acute nicotine abstinence effects on craving and cognitive function.

PubMed

Lerman, Caryn; Gu, Hong; Loughead, James; Ruparel, Kosha; Yang, Yihong; Stein, Elliot A

2014-05-01

Interactions of large-scale brain networks may underlie cognitive dysfunctions in psychiatric and addictive disorders. To test the hypothesis that the strength of coupling among 3 large-scale brain networks--salience, executive control, and default mode--will reflect the state of nicotine withdrawal (vs smoking satiety) and will predict abstinence-induced craving and cognitive deficits and to develop a resource allocation index (RAI) that reflects the combined strength of interactions among the 3 large-scale networks. A within-subject functional magnetic resonance imaging study in an academic medical center compared resting-state functional connectivity coherence strength after 24 hours of abstinence and after smoking satiety. We examined the relationship of abstinence-induced changes in the RAI with alterations in subjective, behavioral, and neural functions. We included 37 healthy smoking volunteers, aged 19 to 61 years, for analyses. Twenty-four hours of abstinence vs smoking satiety. Inter-network connectivity strength (primary) and the relationship with subjective, behavioral, and neural measures of nicotine withdrawal during abstinence vs smoking satiety states (secondary). The RAI was significantly lower in the abstinent compared with the smoking satiety states (left RAI, P = .002; right RAI, P = .04), suggesting weaker inhibition between the default mode and salience networks. Weaker inter-network connectivity (reduced RAI) predicted abstinence-induced cravings to smoke (r = -0.59; P = .007) and less suppression of default mode activity during performance of a subsequent working memory task (ventromedial prefrontal cortex, r = -0.66, P = .003; posterior cingulate cortex, r = -0.65, P = .001). Alterations in coupling of the salience and default mode networks and the inability to disengage from the default mode network may be critical in cognitive/affective alterations that underlie nicotine dependence.

Predictions of High Strain Rate Failure Modes in Layered Aluminum Composites

NASA Astrophysics Data System (ADS)

Khanikar, Prasenjit; Zikry, M. A.

2014-01-01

A dislocation density-based crystalline plasticity formulation, specialized finite-element techniques, and rational crystallographic orientation relations were used to predict and characterize the failure modes associated with the high strain rate behavior of aluminum layered composites. Two alloy layers, a high strength alloy, aluminum 2195, and an aluminum alloy 2139, with high toughness, were modeled with representative microstructures that included precipitates, dispersed particles, and different grain boundary distributions. Different layer arrangements were investigated for high strain rate applications and the optimal arrangement was with the high toughness 2139 layer on the bottom, which provided extensive shear strain localization, and the high strength 2195 layer on the top for high strength resistance The layer thickness of the bottom high toughness layer also affected the bending behavior of the roll-bonded interface and the potential delamination of the layers. Shear strain localization, dynamic cracking, and delamination are the mutually competing failure mechanisms for the layered metallic composite, and control of these failure modes can be used to optimize behavior for high strain rate applications.

Comparison of the bond strength of stainless steel orthodontic brackets bonded to crown porcelains.

PubMed

Chay, Siew Han; Wattanapayungkul, Pranee; Yap, Adrian U Jin; Loh, Poey Ling; Chung, Sew Meng

2005-05-01

The bond strengths and mode of failure of stainless steel orthodontic brackets bonded to the newer all-ceramic crown systems has not been fully investigated. To compare the shear-peel bond strengths and modes of failure of stainless steel Begg orthodontic brackets bonded to all-ceramic crown systems (Finesse, Empress II) and a conventional feldsphatic crown porcelain (Vita Omega 900). Fifteen flat-surface discs of three crown porcelains (Finesse, Vita Omega 900, Empress II) were made and mounted in acrylic moulds. The discs were pumiced, etched with phosphoric acid, primed with silane, and a flat stainless steel Begg bracket bonded to each disc with a chemical cure composite resin (Unite Bond). The discs were stored for one week in water and debonded with a sheer-peel load in an Instron uniaxial testing system with a crosshead speed of 0.5 mm/min. The composite remnants on the ceramic surfaces were classified using the Adhesive Remnant Index (ARI). The bond strength of Finesse (15.03 +/- 1.90 MPa) was significantly greater (p < 0.001) than Vita Omega 900 11.51 +/- 2.35 MPa) and Empress II (11.12 +/- 1.78 MPa). There were no significant differences among the ARI scores. The mode of failure was a mixture of adhesive and cohesive failure. The results indicate that the bond strengths of stainless steel orthodontic brackets bonded to Finesse and Empress II porcelains are clinically acceptable.

VCD Robustness of the Amide-I and Amide-II Vibrational Modes of Small Peptide Models.

PubMed

Góbi, Sándor; Magyarfalvi, Gábor; Tarczay, György

2015-09-01

The rotational strengths and the robustness values of amide-I and amide-II vibrational modes of For(AA)n NHMe (where AA is Val, Asn, Asp, or Cys, n = 1-5 for Val and Asn; n = 1 for Asp and Cys) model peptides with α-helix and β-sheet backbone conformations were computed by density functional methods. The robustness results verify empirical rules drawn from experiments and from computed rotational strengths linking amide-I and amide-II patterns in the vibrational circular dichroism (VCD) spectra of peptides with their backbone structures. For peptides with at least three residues (n ≥ 3) these characteristic patterns from coupled amide vibrational modes have robust signatures. For shorter peptide models many vibrational modes are nonrobust, and the robust modes can be dependent on the residues or on their side chain conformations in addition to backbone conformations. These robust VCD bands, however, provide information for the detailed structural analysis of these smaller systems. © 2015 Wiley Periodicals, Inc.

Magnetic annihilation of the dark mode in a strongly coupled bright-dark terahertz metamaterial.

PubMed

Manjappa, Manukumara; Turaga, Shuvan Prashant; Srivastava, Yogesh Kumar; Bettiol, Andrew Anthony; Singh, Ranjan

2017-06-01

Dark mode in metamaterials has become a vital component in determining the merit of the Fano type of interference in the system. Its strength dictates the enhancement and suppression in the amplitude and Q-factors of resulting resonance features. In this work, we experimentally probe the effect of strong near-field coupling on the strength of the dark mode in a concentrically aligned bright resonator and a dark split ring resonator (SRR) system exhibiting the classical analog of the electromagnetically induced transparency effect. An enhanced strong magnetic field between the bright-dark resonators destructively interferes with the inherent magnetic field of the dark mode to completely annihilate its effect in the coupled system. Moreover, the observed annihilation effect in the dark mode has a direct consequence on the disappearance of the SRR effect in the proposed system, wherein under the strong magnetic interactions, the LC resonance feature of the split ring resonator becomes invisible to the incident terahertz wave.

Energy transfer in mesoscopic vibrational systems enabled by eigenfrequency fluctuations

NASA Astrophysics Data System (ADS)

Atalaya, Juan

Energy transfer between low-frequency vibrational modes can be achieved by means of nonlinear coupling if their eigenfrequencies fulfill certain nonlinear resonance conditions. Because of the discreteness of the vibrational spectrum at low frequencies, such conditions may be difficult to satisfy for most low-frequency modes in typical mesoscopic vibrational systems. Fluctuations of the vibrational eigenfrequencies can also be relatively strong in such systems. We show that energy transfer between modes can occur in the absence of nonlinear resonance if frequency fluctuations are allowed. The case of three modes with cubic nonlinear coupling and no damping is particularly interesting. It is found that the system has a non-thermal equilibrium state which depends only on the initial conditions. The rate at which the system approaches to such state is determined by the parameters such as the noise strength and correlation time, the nonlinearity strength and the detuning from exact nonlinear resonance. We also discuss the case of many weakly coupled modes. Our results shed light on the problem of energy relaxation of low-frequency vibrational modes into the continuum of high-frequency vibrational modes. The results have been obtained with Mark Dykman. Alternative email: jatalaya2012@gmail.com.

Chiral photonic crystal fibers with single mode and single polarization

NASA Astrophysics Data System (ADS)

Li, She; Li, Junqing

2015-12-01

Chiral photonic crystal fiber (PCF) with a solid core is numerically investigated by a modified chiral plane-wave expansion method. The effects of structural parameters and chirality strength are analyzed on single-polarization single-mode range and polarization states of guided modes. The simulation demonstrates that the chiral photonic crystal fiber compared to its achiral counterpart possesses another single-circular-polarization operation range, which is located in the short-wavelength region. The original single-polarization operation range in the long-wavelength region extends to the short wavelength caused by introducing chirality. Then this range becomes a broadened one with elliptical polarization from linear polarization. With increase of chirality, the two single-polarization single-mode ranges may fuse together. By optimizing the structure, an ultra-wide single-circular-polarization operation range from 0.5 μm to 1.67 μm for chiral PCF can be realized with moderate chirality strength.

Experimental investigation of mode I fracture for brittle tube-shaped particles

NASA Astrophysics Data System (ADS)

Stasiak, Marta; Combe, Gaël; Desrues, Jacques; Richefeu, Vincent; Villard, Pascal; Armand, Gilles; Zghondi, Jad

2017-06-01

We focus herein on the mechanical behavior of highly crushable grains. The object of our interest, named shell, is a hollow cylinder grain with ring cross-section, made of baked clay. The objective is to model the fragmentation of such shells, by means of discrete element (DE) approach. To this end, fracture modes I (opening fracture) and II (in-plane shear fracture) have to be investigated experimentally. This paper is essentially dedicated to mode I fracture. Therefore, a campaign of Brazilian-like compression tests, that result in crack opening, has been performed. The distribution of the occurrence of tensile strength is shown to obey a Weibull distribution for the studied shells, and Weibull's modulus was quantified. Finally, an estimate of the numerical/physical parameters required in a DE model (local strength), is proposed on the basis of the energy required to fracture through a given surface in mode I or II.

An experimental investigation of silicon wafer surface roughness and its effect on the full strength of plated metals

NASA Technical Reports Server (NTRS)

Spiers, G. D.

1981-01-01

Plated silicon wafers with surface roughness ranging from 0.4 to 130 microinches were subjected to tensile pull strength tests. Electroless Ni/electroless Cu/electroplated Cu and electroless Ni/electroplated Cu were the two types of plate contacts tested. It was found that smoother surfaces had higher pull strength than rougher, chemically etched surfaces. The presence of the electroless Cu layer was found to be important to adhesion. The mode of fracture of the contact as it left the silicon was studied, and it was found that in almost all cases separation was due to fracture of the bulk silicon phase. The correlation between surface roughness and mode of contact failure is presented and interpreted.

46 CFR 160.041-4 - Contents.

Code of Federal Regulations, 2011 CFR

2011-10-01

... package No. of packages Bandage compress—4″ 1 Single 5 Bandage compress—2″ 4 do 2 Waterproof adhesive..., forceps, scissors, 12 safety pins 1, 1, 1, and 12, respectively Double 1 Wire splint 1 Single 1 Ammonia..., 61/2 gr tablets, vials of 20 5 Double 1 Sterile petrolatum gauze, 3″×18″ 4 Single 3 (c) Instructions...

Occurrence of Children's Echoic Responses According to Interlocutory Question Types.

ERIC Educational Resources Information Center

Fay, Warren H.

Dialogues with 22 echoic 3-year-old children were analyzed according to question type to determine whether some questions are more likely than others to trigger echoic responses. The children were asked to identify and manipulate toy objects such as a car, to identify a group of familiar objects such as a key or scissors, and to respond to…

A SHORT HISTORY CSISRS - AT THE CUTTING EDGE OF NUCLEAR DATA INFORMATION STORAGE AND RETRIEVAL SYSTEMS AND ITS RELATIONSHIP TO CINDA, EXFOR AND ENDF.

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

HOLDEN, N.E.

A short history of CSISRS, pronounced ''scissors'' and standing for the Cross Section Information Storage and Retrieval System, is given. The relationship of CSISRS to CINDA, to the neutron nuclear data four-centers, to EXFOR and to ENDF, the evaluated neutron nuclear data file, is briefly explained.

Mesoscopic interactions and species coexistence in evolutionary game dynamics of cyclic competitions.

PubMed

Cheng, Hongyan; Yao, Nan; Huang, Zi-Gang; Park, Junpyo; Do, Younghae; Lai, Ying-Cheng

2014-12-15

Evolutionary dynamical models for cyclic competitions of three species (e.g., rock, paper, and scissors, or RPS) provide a paradigm, at the microscopic level of individual interactions, to address many issues in coexistence and biodiversity. Real ecosystems often involve competitions among more than three species. By extending the RPS game model to five (rock-paper-scissors-lizard-Spock, or RPSLS) mobile species, we uncover a fundamental type of mesoscopic interactions among subgroups of species. In particular, competitions at the microscopic level lead to the emergence of various local groups in different regions of the space, each involving three species. It is the interactions among the groups that fundamentally determine how many species can coexist. In fact, as the mobility is increased from zero, two transitions can occur: one from a five- to a three-species coexistence state and another from the latter to a uniform, single-species state. We develop a mean-field theory to show that, in order to understand the first transition, group interactions at the mesoscopic scale must be taken into account. Our findings suggest, more broadly, the importance of mesoscopic interactions in coexistence of great many species.

Stochastic Evolution Dynamic of the Rock-Scissors-Paper Game Based on a Quasi Birth and Death Process

NASA Astrophysics Data System (ADS)

Yu, Qian; Fang, Debin; Zhang, Xiaoling; Jin, Chen; Ren, Qiyu

2016-06-01

Stochasticity plays an important role in the evolutionary dynamic of cyclic dominance within a finite population. To investigate the stochastic evolution process of the behaviour of bounded rational individuals, we model the Rock-Scissors-Paper (RSP) game as a finite, state dependent Quasi Birth and Death (QBD) process. We assume that bounded rational players can adjust their strategies by imitating the successful strategy according to the payoffs of the last round of the game, and then analyse the limiting distribution of the QBD process for the game stochastic evolutionary dynamic. The numerical experiments results are exhibited as pseudo colour ternary heat maps. Comparisons of these diagrams shows that the convergence property of long run equilibrium of the RSP game in populations depends on population size and the parameter of the payoff matrix and noise factor. The long run equilibrium is asymptotically stable, neutrally stable and unstable respectively according to the normalised parameters in the payoff matrix. Moreover, the results show that the distribution probability becomes more concentrated with a larger population size. This indicates that increasing the population size also increases the convergence speed of the stochastic evolution process while simultaneously reducing the influence of the noise factor.

Teaching: the Wave Mechanics of McLeods' Stringy Electron, Explicit Nucleons, and Through-the-Earth Projections of Constellations' Stick Figures

NASA Astrophysics Data System (ADS)

McLeod, Roger David; McLeod, David Matthew

2012-02-01

This shows how Hooke's law, for electron, proton and neutron, 2D and 3D, strings, builds electromagnetic string-waves, extending, and pleasing, Schr"odinger. These are composed of spirally linked, parallel, north-pole oriented, neutrino and antineutrino strings, stable by magnetic repulsions. Their Dumbo Proton is antineutrino-scissor cut, and compressed in the vicinity of a neutron star, where electrostatic marriage occurs with a neutrino-scissor cut, and compressed, electron, so a Mickey Neutron emerges. Strings predict: electron charge is - 1/3 e, Dumbo P is 25 % longer than Mickey N, and Hooke says relaxing springs fuel three, separate, non-eternal, inflations, after Big Bangs. Gravity is strings, longitudinally linked. Einstein says Herman Grid's black diagonals prove human vision reads its information from algebraically-signed electromagnetic field distributions, (diffraction) patterns, easily known by ray-tracing, not requiring difficult Spatial Fourier Transformation. High-schoolers understand its application to Wave Mechanics, agreeing that positive-numbered probabilities do not enter, to possibly displease God. Detected stick-figure forms of constellations: like Phoenix, Leo, Canis Major, and especially Orion, fool some observers into false beliefs in things like UFHumanoids, or Kokopelli, Pele and Pamola!

Six years follow-up of a penis replantation in a child.

PubMed

de Lagausie, Pascal; Jehanno, Pascal

2008-03-01

Total amputation of the penis is very rare in a child. This article presents a case of a traumatic penile amputation at the base of the perineum, with scissors, in a 4-year-old child. Six hours after the aggression, the penis was replanted. Three weeks after the intervention, except for skin necrosis, the results were excellent. Six years afterward, this child has done very well from pediatric, psychological, urological, and plastic surgery points of view. Sensibility and erections are present and normal. Longer follow-ups particularly during puberty are necessary. Total amputation of the penis is a very rare accident in a child. Partial lesions are more common, particularly during circumcision. As in adult cases, replantation of the penis in a child needs a clean section by scissors or a knife, a correct conservation of the penis (in ice but without direct contact), and a short period between the lesion and the surgical procedure. All these conditions explain that very few cases are reported in the literature. We present a case of amputation of the penis in a 4-year-old child, with good results 6 years afterward.

Traffic jams induce dynamical phase transition in spatial rock-paper-scissors game

NASA Astrophysics Data System (ADS)

Nagatani, Takashi; Ichinose, Genki; Tainaka, Kei-ichi

2018-02-01

Spatial and temporal behaviors of the rock-paper-scissors (RPS) game is key to understanding not only biodiversity but also a variety of cyclic systems. It has been demonstrated that, in the stochastic cellular automaton of RPS game, three species cannot survive on one-dimensional (1-d) lattice; only a single species survives. Previous studies have shown that three species are able to coexist if the migration of species is considered. However, their definitions of migration are the swapping of two species or the random walk of species, which rarely occurs in nature. Here, we investigate the effect of migration by using the 1-d lattice traffic model in which species can move rightward if the site ahead is empty. Computer simulations reveal that three species can survive at the same time within the wide range of parameter values. At low densities, all species can coexist. In contrast, the extinction of two species occurs if the density exceeds the critical limit of the jamming transition. This dynamical phase transition between the coexistence and single (non-coexistence) phase clearly separates due to the self-organized pattern: condensation and rarefaction in the stripe-pattern of three species.

Scalable, MEMS-enabled, vibrational tactile actuators for high resolution tactile displays

NASA Astrophysics Data System (ADS)

Xie, Xin; Zaitsev, Yuri; Velásquez-García, Luis Fernando; Teller, Seth J.; Livermore, Carol

2014-12-01

The design, fabrication, and characterization of a new type of tactile display for people with blindness or low vision is reported. Each tactile element comprises a piezoelectric extensional actuator that vibrates in plane, with a microfabricated scissor mechanism to convert the in-plane actuations into robust, higher-amplitude, out-of-plane (vertical) vibrations that are sensed with the finger pads. When the tactile elements are formed into a 2D array, information can be conveyed to the user by varying the pattern of vibrations in space and time. Analytical models and finite element analysis were used to design individual tactile elements, which were implemented with PZT actuators and both SU-8 and 3D-printed scissor amplifiers. The measured displacements of these 3 mm × 10 mm, MEMS-enabled tactile elements exceed 10 µm, in agreement with models, with measured forces exceeding 45 mN. The performance of the MEMS-enabled tactile elements is compared with the performance of larger, fully-macroscale tactile elements to demonstrate the scale dependence of the devices. The creation of a 28-element prototype is also reported, and the qualitative user experience with the individual tactile elements and displays is described.

Old scissors to industrial automation: the impact of technologic evolution on worker's health.

PubMed

Teodoroski, Rita de Cassia Clark; Koppe, Vanessa Mazzocchi; Merino, Eugênio Andrés Díaz

2012-01-01

To cut a fabric, the professional performs different jobs and among them stands out the cut. The scissors has been the instrument most used for this activity. Over the years, technology has been conquering its space in the textile industry. However, despite the industrial automation able to offer subsidies to answer employment market demands, without appropriate orientation, the worker is exposed to the risks inherent at the job. Ergonomics is a science that search to promote the comfort and well being in consonance with efficacy. Its goals are properly well defined and clearly guide the actions aimed at transforming the working conditions. This study aimed to analyze the activity of cut tissues with a machine by a seamstress and the implications on their body posture. The methodology used was the observation technique and application of the Protocol RULA, where the result obtained was the level 3 and score 5, confirming that "investigations and changes are required soon". Conclude that using the machine to tissue cut should be encouraged, but in conjunction with orientations for improving posture while handling it. It seeks to prevent dysfunction of the musculoskeletal system that prevents employees from performing their work tasks efficiently and productively.

Serial Casting as an Adjunct to Botulinum Toxin Type A Treatment in Children With Cerebral Palsy and Spastic Paraparesis With Scissoring of the Lower Extremities.

PubMed

Dai, Alper I; Demiryürek, Abdullah T

2017-06-01

The purpose of this study was to examine whether combination therapy of serial casting and botulinum toxin type A injection can further enhance the effects of botulinum toxin type A in children with cerebral palsy with scissoring of both legs. This study was a prospective and randomized trial. The children were divided into 2 groups, one of which received serial casting after botulinum toxin type A (n = 40), and the other which only received botulinum toxin type A (n = 40). Serial casting started 3 weeks after the botulinum toxin type A. Both groups received physiotherapy. Groups were assessed at baseline then compared at 6 and 12 weeks following the intervention. Significant improvements in Gross Motor Function Measure-66 and Caregiver Health Questionnaire were recorded in both groups ( P < .001). The modified Ashworth scale improved significantly following botulinum toxin type A in the serial casting group ( P < .05), but not in botulinum toxin type A only group. These results suggest that serial casting after botulinum toxin type A can enhance the benefits of botulinum toxin type A in children with cerebral palsy.

An experimental investigation of evolutionary dynamics in the Rock-Paper-Scissors game.

PubMed

Hoffman, Moshe; Suetens, Sigrid; Gneezy, Uri; Nowak, Martin A

2015-03-06

Game theory describes social behaviors in humans and other biological organisms. By far, the most powerful tool available to game theorists is the concept of a Nash Equilibrium (NE), which is motivated by perfect rationality. NE specifies a strategy for everyone, such that no one would benefit by deviating unilaterally from his/her strategy. Another powerful tool available to game theorists are evolutionary dynamics (ED). Motivated by evolutionary and learning processes, ED specify changes in strategies over time in a population, such that more successful strategies typically become more frequent. A simple game that illustrates interesting ED is the generalized Rock-Paper-Scissors (RPS) game. The RPS game extends the children's game to situations where winning or losing can matter more or less relative to tying. Here we investigate experimentally three RPS games, where the NE is always to randomize with equal probability, but the evolutionary stability of this strategy changes. Consistent with the prediction of ED we find that aggregate behavior is far away from NE when it is evolutionarily unstable. Our findings add to the growing literature that demonstrates the predictive validity of ED in large-scale incentivized laboratory experiments with human subjects.

Stochastic Evolution Dynamic of the Rock-Scissors-Paper Game Based on a Quasi Birth and Death Process.

PubMed

Yu, Qian; Fang, Debin; Zhang, Xiaoling; Jin, Chen; Ren, Qiyu

2016-06-27

Stochasticity plays an important role in the evolutionary dynamic of cyclic dominance within a finite population. To investigate the stochastic evolution process of the behaviour of bounded rational individuals, we model the Rock-Scissors-Paper (RSP) game as a finite, state dependent Quasi Birth and Death (QBD) process. We assume that bounded rational players can adjust their strategies by imitating the successful strategy according to the payoffs of the last round of the game, and then analyse the limiting distribution of the QBD process for the game stochastic evolutionary dynamic. The numerical experiments results are exhibited as pseudo colour ternary heat maps. Comparisons of these diagrams shows that the convergence property of long run equilibrium of the RSP game in populations depends on population size and the parameter of the payoff matrix and noise factor. The long run equilibrium is asymptotically stable, neutrally stable and unstable respectively according to the normalised parameters in the payoff matrix. Moreover, the results show that the distribution probability becomes more concentrated with a larger population size. This indicates that increasing the population size also increases the convergence speed of the stochastic evolution process while simultaneously reducing the influence of the noise factor.

(CaO)nIrO2 (n = 1, 2, 4) family: Chemical scissors effects of CaO on structural characteristics correlated to physical properties. Ab initio study

NASA Astrophysics Data System (ADS)

Matar, Samir F.; Etourneau, Jean

2017-11-01

Based on crystal chemistry analysis within Ca-Ir-O ternary, the generic (CaO)nIrO2 formula leading to CaIrO3 for n = 1, Ca2IrO4 for n = 2 and Ca4IrO6 for n = 4 actual chemical compounds show significant structural changes regarding the spatial arrangement of IrO6 octahedra whereby increasing amounts of CaO act as 'chemical scissor' decreasing the dimensionality of stacking octahedra from 3D (IrO2) to 0D (Ca4IrO6). This is accompanied by changes in the electronic structure investigated within density functional theory. Such changes are particularly exhibited by linear increase of Ir density of states at the Fermi level revealing increasing localization of d states with crystal field effects. Eventually only for Ca4IrO6 a magnetic instability occurs in non magnetic configuration. Spin polarized calculations lead to development of small magnitude but finite magnetization on Ir with M 0.50 μB totally polarized along minority spin channel ↓.

Corrosion protection of reusable surgical instruments.

PubMed

Shah, Sadiq; Bernardo, Mildred

2002-01-01

To understand the corrosion properties of surgical scissors, 416 stainless steel disks and custom electrodes were used as simulated surfaces under various conditions. These simulated surfaces were exposed to tap water and 400-ppm synthetic hard water as Ca2CO3 under different conditions. The samples were evaluated by various techniques for corrosion potential and the impact of environmental conditions on the integrity of the passive film. The electrodes were used to monitor the corrosion behavior by potentiodynamic polarization technique in water both in the presence and absence of a cleaning product. The surface topography of the 416 stainless steel disks was characterized by visual observations and scanning electron microscopy (SEM), and the surface chemistry of the passive film on the surface of the scissors was characterized by x-ray photoelectron spectroscopy (XPS). The results suggest that surgical instruments made from 416 stainless steel are not susceptible to uniform corrosion; however, they do undergo localized corrosion. The use of suitable cleaning products can offer protection against localized corrosion during the cleaning step. More importantly, the use of potentiodynamic polarization techniques allowed for a quick and convenient approach to evaluate the corrosion properties of surgical instruments under a variety of simulated-use environmental conditions.

Estimation of rail wear limits based on rail strength investigations

DOT National Transportation Integrated Search

1998-12-01

This report describes analyses performed to estimate limits on rail wear based on strength investigations. Two different failure modes are considered in this report: (1) permanent plastic bending, and (2) rail fracture. Rail bending stresses are calc...

On cyclic yield strength in definition of limits for characterisation of fatigue and creep behaviour

NASA Astrophysics Data System (ADS)

Gorash, Yevgen; MacKenzie, Donald

2017-06-01

This study proposes cyclic yield strength as a potential characteristic of safe design for structures operating under fatigue and creep conditions. Cyclic yield strength is defined on a cyclic stress-strain curve, while monotonic yield strength is defined on a monotonic curve. Both values of strengths are identified using a two-step procedure of the experimental stress-strain curves fitting with application of Ramberg-Osgood and Chaboche material models. A typical S-N curve in stress-life approach for fatigue analysis has a distinctive minimum stress lower bound, the fatigue endurance limit. Comparison of cyclic strength and fatigue limit reveals that they are approximately equal. Thus, safe fatigue design is guaranteed in the purely elastic domain defined by the cyclic yielding. A typical long-term strength curve in time-to-failure approach for creep analysis has two inflections corresponding to the cyclic and monotonic strengths. These inflections separate three domains on the long-term strength curve, which are characterised by different creep fracture modes and creep deformation mechanisms. Therefore, safe creep design is guaranteed in the linear creep domain with brittle failure mode defined by the cyclic yielding. These assumptions are confirmed using three structural steels for normal and high-temperature applications. The advantage of using cyclic yield strength for characterisation of fatigue and creep strength is a relatively quick experimental identification. The total duration of cyclic tests for a cyclic stress-strain curve identification is much less than the typical durations of fatigue and creep rupture tests at the stress levels around the cyclic yield strength.

Strength of Default Mode Resting-State Connectivity Relates to White Matter Integrity in Children

ERIC Educational Resources Information Center

Gordon, Evan M.; Lee, Philip S.; Maisog, Jose M.; Foss-Feig, Jennifer; Billington, Michael E.; VanMeter, John; Vaidya, Chandan J.

2011-01-01

A default mode network of brain regions is known to demonstrate coordinated activity during the resting state. While the default mode network is well characterized in adults, few investigations have focused upon its development. We scanned 9-13-year-old children with diffusion tensor imaging and resting-state functional magnetic resonance imaging.…

Enamel Bond Strength of New Universal Adhesive Bonding Agents.

PubMed

McLean, D E; Meyers, E J; Guillory, V L; Vandewalle, K S

2015-01-01

Universal bonding agents have been introduced for use as self-etch or etch-and-rinse adhesives depending on the dental substrate and clinician's preference. The purpose of this study was to evaluate the shear bond strength (SBS) of composite to enamel using universal adhesives compared to a self-etch adhesive when applied in self-etch and etch-and-rinse modes over time. Extracted human third molars were used to create 120 enamel specimens. The specimens were ground flat and randomly divided into three groups: two universal adhesives and one self-etch adhesive. Each group was then subdivided, with half the specimens bonded in self-etch mode and half in etch-and-rinse mode. The adhesives were applied as per manufacturers' instructions, and composite was bonded using a standardized mold and cured incrementally. The groups were further divided into two subgroups with 10 specimens each. One subgroup was stored for 24 hours and the second for six months in 37°C distilled water and tested in shear. Failure mode was also determined for each specimen. A three-way analysis of variance (ANOVA) found a significant difference between groups based on bonding agent (p<0.001) and surface treatment (p<0.001) but not on time (p=0.943), with no significant interaction (p>0.05). Clearfil SE in etch-and-rinse and self-etch modes had more mixed fractures than either universal adhesive in either mode. Etching enamel significantly increased the SBS of composite to enamel. Clearfil SE had significantly greater bond strength to enamel than either universal adhesive, which were not significantly different from each other.

A study on fatigue strength reduction factor for small diameter socket welded pipe joints

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

Higuchi, Makoto; Nakagawa, Akira; Hayashi, Makoto

1996-12-01

Factors that may exert influence on the fatigue strength of small diameter socket welded joints of nominal diameter in the 20--50 mm range have been investigated by the fully reversed four-point bending fatigue test with the material, diameter, pipe schedule, throat depth, bead shape, slip-on gap, and root defect as the testing parameters. The fatigue strength of socket joints depended acutely on the diameter. When the diameter is large, the fatigue strength tended to be low and the fracture is of the root-failure mode; when it is small, on the other hand, the fatigue strength is high and the fracturemore » is of the toe-failure mode. Stainless steel proved to be superior to carbon steel; it gave rise to 1.37 times the fatigue strength of the latter for socket joints of nominal diameter 50 mm; the fatigue strength reduction factor determined at 10{sup 7} cycles with respect to the fatigue strength of smooth base metal in the fully reversed fatigue was about 4 for stainless steel and about 5 for carbon steel. The fatigue strength was higher, the larger the Sche number (i.e., the thicker the pipe wall); it was improved markedly by placing one final refinement pass on the toe or by eliminating the slip-on gap. An empirical formula relating the size of the root defect to the fatigue strength reduction has been proposed.« less

Quadriceps Strength in Patients With Isolated Cartilage Defects of the Knee: Results of Isokinetic Strength Measurements and Their Correlation With Clinical and Functional Results

PubMed Central

Hirschmüller, Anja; Andres, Tasja; Schoch, Wolfgang; Baur, Heiner; Konstantinidis, Lukas; Südkamp, Norbert P.; Niemeyer, Philipp

2017-01-01

Background: Recent studies have found a significant deficit of maximum quadriceps strength after autologous chondrocyte implantation (ACI) of the knee. However, it is unclear whether muscular strength deficits in patients with cartilage damage exist prior to operative treatment. Purpose: To isokinetically test maximum quadriceps muscle strength and quantify the impact of possible strength deficits on functional and clinical test results. Study Design: Cross-sectional study; Level of evidence, 3. Methods: To identify clinically relevant muscular strength deficits, 24 patients (5 females, 19 males; mean age, 34.5 years; body mass index, 25.9 kg/m2) with isolated cartilage defects (mean onset, 5.05 years; SD, 7.8 years) in the knee joint underwent isokinetic strength measurements. Maximal quadriceps strength was recorded in 3 different testing modes: pure concentric contraction (flexors and extensors alternating work; con1), concentric-eccentric (only the extensors work concentrically and eccentrically; con2), and eccentric contraction in the alternating mode (ecc). Results were compared for functional performance (single-leg hop test), pain scales (visual analog scale [VAS], numeric rating scale [NRS]), self-reported questionnaires (International Knee Documentation Committee [IKDC], Knee Injury and Osteoarthritis Outcome Scale [KOOS]), and defect size (cm2). Results: Compared with the uninjured leg, significantly lower quadriceps strength was detected in the injured leg in all isokinetic working modes (con1 difference, 27.76 N·m [SD 17.47; P = .003]; con2 difference, 21.45 N·m [SD, 18.45; P =.025]; ecc difference, 29.48 N·m [SD, 21.51; P = .001]), with the largest deficits found for eccentric muscle performance. Moderate negative correlations were observed for the subjective pain scales NRS and VAS. The results of the IKDC and KOOS questionnaires showed low, nonsignificant correlations with findings in the isokinetic measurement. Moreover, defect sizes (mean, 3.13 cm2) were of no importance regarding the prediction of the strength deficit. The quadriceps strength deficit between the injured and the uninjured leg was best predicted by the results of the single-leg hop test. Conclusion: Patients with isolated cartilage defects of the knee joint have significant deficits in quadriceps muscle strength of the injured leg compared with the uninjured leg. The single-leg hop test may be used to predict quadriceps strength deficits. Future research should address whether preoperative strength training in patients with cartilage defects of the knee could be effective and should be taken into consideration in addition to surgical treatment. PMID:28596973

Kinematics of Faulting and Structural Evolution of Neogene Supra-detachment Basins on the Menderes Metamorphic Core Complex, Western Anatolia

NASA Astrophysics Data System (ADS)

Dilek, Y.; Oner, Z.; Davis, E. A.

2007-12-01

The Menderes metamorphic massif (MM) in western Anatolia is a classic core complex with exhumed high-grade crustal rocks intruded by granodioritic plutons and overlain by syn-extensional sedimentary rocks. Timing and the mechanism(s) of the initial exhumation of the MM are controversial, and different hypotheses exist in the literature. Major structural grabens (i.e. Alasehir, Buyuk Menderes) within the MM that are bounded by high-angle and seismically active faults are late-stage brittle structures, which characterize the block-faulting phase in the extensional history of the core complex and are filled with Quaternary sediments. On the southern shoulder of the Alasehir graben high-grade metamorphic rocks of the MM are overlain by the Miocene and younger sedimentary rocks above a N-dipping detachment surface. The nearly 100-m-thick cataclastic shear zone beneath this surface contain S-C fabrics, microfaults, Riedel shears, mica-fish structures and shear bands, all consistently indicating top-to-the North shearing. Granodioritic plutons crosscutting the MM and the detachment surface are exposed within this cataclastic zone, displaying extensional ductile and brittle structures. The oldest sedimentary rocks onlapping the cataclastic shear zone of the MM here are the Middle Miocene lacustrine shale and limestone units, unconformably overlain by the Upper Miocene fluvial and alluvial fan deposits. Extensive development of these alluvial fan deposits by the Late Miocene indicates the onset of range-front faulting in the MM by this time, causing a surge of coarse clastic deposition along the northern edge of the core complex. The continued exhumation and uplift of the MM provided the necessary relief and detrital material for the Plio-Pleistocene fluvial systems in the Alasehir supradetachment basin (ASDB). A combination of rotational normal faulting and scissor faulting in the extending ASDB affected the depositional patterns and drainage systems, and produced local unconformities within the basinal stratigraphy. High-angle, oblique-slip scissor faults crosscutting the MM rocks, the detachment surface and the basinal strata offset them for more than few 100 meters and the fault blocks locally show different structural architecture and metamorphic grades, suggesting differential uplift along these scissor faults. This fault kinematics and the distribution of range-parallel and range-perpendicular faults strongly controlled the shape and depth of the accommodation space within the ASDB. At a more regional scale scissor faulting across the MM seems to have controlled the foci of Plio-Pleistocene point-source volcanism in the Aegean extensional province (e.g. Kula area). There are no major interruptions in the syn-extensional depositional history of the ASDB, ruling out the pulsed-extension models suggesting a period of contractional deformation in the late Cenozoic evolution of the MM. The onset of exhumation and extensional tectonics in the MM and western Anatolia was a result of thermal weakening of the orogenic crust, following a widespread episode of post-collisional magmatism in the broader Aegean region during the Eocene through Miocene.

Unit-Sphere Multiaxial Stochastic-Strength Model Applied to Anisotropic and Composite Materials

NASA Technical Reports Server (NTRS)

Nemeth, Noel, N.

2013-01-01

Models that predict the failure probability of brittle materials under multiaxial loading have been developed by authors such as Batdorf, Evans, and Matsuo. These "unit-sphere" models assume that the strength-controlling flaws are randomly oriented, noninteracting planar microcracks of specified geometry but of variable size. This methodology has been extended to predict the multiaxial strength response of transversely isotropic brittle materials, including polymer matrix composites (PMCs), by considering (1) flaw-orientation anisotropy, whereby a preexisting microcrack has a higher likelihood of being oriented in one direction over another direction, and (2) critical strength, or K (sub Ic) orientation anisotropy, whereby the level of critical strength or fracture toughness for mode I crack propagation, K (sub Ic), changes with regard to the orientation of the microstructure. In this report, results from finite element analysis of a fiber-reinforced-matrix unit cell were used with the unit-sphere model to predict the biaxial strength response of a unidirectional PMC previously reported from the World-Wide Failure Exercise. Results for nuclear-grade graphite materials under biaxial loading are also shown for comparison. This effort was successful in predicting the multiaxial strength response for the chosen problems. Findings regarding stress-state interactions and failure modes also are provided.

Energy harvesting from controlled buckling of piezoelectric beams

NASA Astrophysics Data System (ADS)

Ansari, M. H.; Karami, M. Amin

2015-11-01

A piezoelectric vibration energy harvester is presented that can generate electricity from the weight of passing cars or crowds. The energy harvester consists of a piezoelectric beam, which buckles when the device is stepped on. The energy harvester can have a horizontal or vertical configuration. In the vertical (direct) configuration, the piezoelectric beam is vertical and directly sustains the weight of the vehicles or people. In the horizontal (indirect) configuration, the vertical weight is transferred to a horizontal axial force through a scissor-like mechanism. Buckling of the beam results in significant stresses and, thus, large power production. However, if the beam’s buckling is not controlled, the beam will fracture. To prevent this, the axial deformation is constrained to limit the deformations of the beam. In this paper, the energy harvester is analytically modeled. The considered piezoelectric beam is a general non-uniform beam. The natural frequencies, mode shapes, and the critical buckling force corresponding to each mode shape are calculated. The electro-mechanical coupling and the geometric nonlinearities are included in the model. The design criteria for the device are discussed. It is demonstrated that a device, realized with commonly used piezoelectric patches, can generate tens of milliwatts of power from passing car traffic. The proposed device could also be implemented in the sidewalks or integrated in shoe soles for energy generation. One of the key features of the device is its frequency up-conversion characteristics. The piezoelectric beam undergoes free vibrations each time the weight is applied to or removed from the energy harvester. The frequency of the free vibrations is orders of magnitude larger than the frequency of the load. The device is, thus, both efficient and insensitive to the frequency of the force excitations.

The Detection of 6.9 μm Emission Features in the Infrared Spectra of IRAS 04296+3429, IRAS 05341+0852, and IRAS 22272+5435: Evidence for the Presence of Hn-PAHs in Post-AGB Stars

NASA Astrophysics Data System (ADS)

Materese, Christopher K.; Bregman, Jesse D.; Sandford, Scott A.

2017-12-01

Polycyclic aromatic hydrocarbons (PAHs) are generally believed to be ubiquitous in space and responsible for numerous telltale interstellar infrared emission bands. In Sandford et al., we suggested that PAHs with excess hydrogenation at their periphery ({{{H}}}{{n}}-PAHs) may be an important subclass of these molecules in some astrophysical environments. These molecules are candidates to explain objects with anomalously large 3.4 μm features, which are presumed to be associated with the aliphatic C-H stretching vibrations of the excess hydrogen. In that work, we suggest that for Hn-PAHs to be a viable candidate as the source for this 3.4 μm feature, we must also expect to observe methylene scissoring modes at 6.9 μm. In this work, we continue to develop the {{{H}}}{{n}} - {PAH} hypothesis with a focus on the 6.9 μm feature. We also present some new observations of three post-asymptotic giant branch (post-AGB) objects with abnormally large 3.4 μm features, IRAS 04296+3429, IRAS 05341+0852, and IRAS 22272+5435, in addition to one post-AGB object with normal PAH emissions, IRAS 20000+3239. These observations were made using the FORCAST instrument in grism mode on the Stratospheric Observatory for Infrared Astronomy aircraft and demonstrate the presence of a 6.9 μm feature for the three objects with abnormally large 3.4 μm features and no detectable 6.9 μm feature for the normal PAH emitter. These results are consistent with the hypothesis that Hn-PAHs are a possible source of these infrared emission bands.

Numerical models of delamination behavior in 2G HTS tapes under transverse tension and peel

NASA Astrophysics Data System (ADS)

Duan, Yujie; Ta, Wurui; Gao, Yuanwen

2018-02-01

In extreme operating environments, delamination in 2G HTS tapes occurs within and/or near the superconductor layer from high transverse tensile stresses caused by fabrication, Lorentz forces and thermal mismatch, etc. Generally, transverse opening and peeling off are the main delamination modes, and are always studied in anvil and peel tests, respectively. Numerical models of these modes for 2G HTS tape are presented wherein the mixed-mode traction-separation law at the interface of the silver and superconductor layers is considered. Plastic deformations of copper, silver, and Hastelloy® in the HTS tape are taken into account. The results obtained from the transverse opening model show that the maximum average tensile stress is smaller than the delamination tensile strength because delamination is asynchronous in the tape. When a crack appears in the tape, only a small stress ( ≤ 1 MPa) is required to expand the crack to other stress free areas through peeling. Using the peeling model, the dependency of the peel strength on peeling angle is investigated under constant fracture toughness. Peel strength decreases with the peeling angle until the minimum value is reached at 150°, and thereafter increases slightly. Other results indicate that peel strength depends strongly on delamination strength, fracture toughness, and thickness of copper layer. The fracture toughness of the delamination interface, which is difficult to obtain by experiment, can be extracted using the present model.

Influence of the Conditioning Method for Pre-Sintered Zirconia on the Shear Bond Strength of Bilayered Porcelain/Zirconia

PubMed Central

Spintzyk, Sebastian; Yamaguchi, Kikue; Sawada, Tomofumi; Schille, Christine; Schweizer, Ernst; Ozeki, Masahiko; Geis-Gerstorfer, Jürgen

2016-01-01

This study evaluated the bond strength of veneering porcelain with an experimental conditioner-coated zirconia. Pre-sintered Y-TZP specimens (n = 44) were divided in two groups based on conditioning type. After sintering, all sample surfaces were sandblasted and layered with veneering porcelain. Additionally, half of the specimens in each group underwent thermal cycling (10,000 cycles, 5–55 °C), and all shear bond strengths were measured. After testing, the failure mode of each fractured specimen was determined. Differences were tested by parametric and Fisher’s exact tests (α = 0.05). The differences in bond strength were not statistically significant. Adhesive fractures were dominantly observed for the non-thermal cycled specimens. After thermal cycling, the conditioner-coated group showed cohesive and mixed fractures (p = 0.0021), whereas the uncoated group showed more adhesive fractures (p = 0.0021). Conditioning of the pre-sintered Y-TZP did not change the shear bond strength of the veneering porcelain, but did improve the failure mode after thermal cycling. PMID:28773885

Epistemic Beliefs about Justification Employed by Physics Students and Faculty in Two Different Problem Contexts

NASA Astrophysics Data System (ADS)

Çağlayan Mercan, Fatih

2012-06-01

This study examines the epistemic beliefs about justification employed by physics undergraduate and graduate students and faculty in the context of solving a standard classical physics problem and a frontier physics problem. Data were collected by a think-aloud problem solving session followed by a semi-structured interview conducted with 50 participants, 10 participants at freshmen, seniors, masters, PhD, and faculty levels. Seven modes of justification were identified and used for exploring the relationships between each justification mode and problem context, and expertise level. The data showed that justification modes were not mutually exclusive and many respondents combined different modes in their responses in both problem contexts. Success on solving the standard classical physics problem was not related to any of the justification modes and was independent of expertise level. The strength of the association across the problem contexts for the authoritative, rational, and empirical justification modes fell in the medium range and for the modeling justification mode fell in the large range of practical significance. Expertise level was not related with the empirical and religious justification modes. The strength of the association between the expertise level and the authoritative, rational, experiential, and relativistic justification modes fell in the medium range, and the modeling justification mode fell in the large range of practical significance. The results provide support for the importance of context for the epistemic beliefs about justification and are discussed in terms of the implications for teaching and learning science.

Influence of each Zernike aberration on the propagation of laser beams through atmospheric turbulence

NASA Astrophysics Data System (ADS)

Azarian, Adrian; Gladysz, Szymon

2014-10-01

We study the influence of each Zernike mode on the propagation of a laser beam through the atmosphere by two different numerical methods. In the first method, an idealized adaptive optics system is modeled to subtract a certain number of Zernike modes from the beam. The effect of each aberration is quantified using the Strehl ratio of the longterm exposure in target/receiver plane. In the second method, the strength of each Zernike mode is varied using a numerical space-filling design during the generation of the phase screens. The resulting central intensity for each point of the design is then studied by a linear discriminant analysis, which yields to the importance of each Zernike mode. The results of the two methods are consistent. They indicate that, for a focused Gaussian beam and for certain geometries and turbulence strengths, the hypothesis of diminishing gains with correction of each new mode is not true. For such cases, we observe jumps in the calculated criteria, which indicate an increased importance of some particular modes, especially coma. The implications of these results for the design of adaptive optics systems are discussed.

Evaluation of composite flattened tubular specimen. [fatigue tests

NASA Technical Reports Server (NTRS)

Liber, T.; Daniel, I. M.

1978-01-01

Flattened tubular specimens of graphite/epoxy, S-glass/epoxy, Kevlar-49/epoxy, and graphite/S-glass/epoxy hybrid materials were evaluated under static and cyclic uniaxial tensile loading and compared directly with flat coupon data of the same materials generated under corresponding loading conditions. Additional development for the refinement of the flattened specimen configuration and fabrication was required. Statically tested graphite/epoxy, S-glass/epoxy, and Kevlar 49/epoxy flattened tube specimens exhibit somewhat higher average strengths than their corresponding flat coupons. Flattened tube specimens of the graphite/S-glass/epoxy hybrid and the graphite/epoxy flattened tube specimens failed in parasitic modes with consequential lower strength than the corresponding flat coupons. Fatigue tested flattened tube specimens failed in parasitic modes resulting in lower fatigue strengths than the corresponding flat coupons.

Space Food Package - Gemini-Titan (GT)-4 Flight - MSC

NASA Image and Video Library

1965-05-01

Food packages of beef and gravy fully reconstituted and ready to eat. An astronaut would squeeze food through opening at right side of package. Water gun is used to reconstitute dehydrated food. Scissors are used to open packages. This is the type of space food which will be used on the Gemini-Titan 4 spaceflight. MSC, Houston, TX *S65-24895 thru S65-24899

Air Saturation Dive 4 - 8 February 1980, CEDD Test Number 1-80.

DTIC Science & Technology

1980-09-01

heart rate. Blood pressure measurements will be recorded. A finger-prick blood sample will be required from each subject for microhematocrit...manoeuvres on command from the surface. Termination Criteria. With the exception of the finger-prick blood sample for microhematocrit determination, all...each experimental period. 3. Scissors, alligator clips - 4 clips/subject. 4. Metric steel tape measure. 5. Impedance cardiography connecting cables - I

Treatment of Neuropathic Pain after SCI with a Catalytic Oxidoreductant

DTIC Science & Technology

2015-10-01

opening the scissor. The thoracic aorta was visualized and a small aneurysm clip was placed on the aorta at the level of T8 to induce ischemic injury...into aorta via left ventricle and a small cut was made on right atrium. The vasculature was 6 | P a g e     briefly rinsed with 60 mL saline by

Hair cuttime on ISS

NASA Image and Video Library

2015-03-22

Caption: ISS043E044174 (03/22/2015) --- Its haircut time onboard the International Space Station as Expedition 43 Commander and NASA astronaut Terry Virts handles the scissors while ESA (European Space Agency) astronaut Samantha Cristoforetti holds the vacuum to immediately pull the fine hair strands into the safe container so they don't float away into the station. Hair trims are a regular occurrence during an astronaut's six month tour.

Pile et Face: Avec du papier, des images, de la colle...et des ciseaux (Heads and Tails: With Paper, Pictures, Glue...and Scissors).

ERIC Educational Resources Information Center

Vever, Daniel

1991-01-01

A kit using the concept of puzzles as a focus for developing self-correcting instructional materials for French language teaching is described. The kit, designed for teachers and including 47 ideas organized by theme, contains matrices and cards for a variety of exercises at various levels and suggestions for their use. (MSE)

Optimization of Quantitative Proteomics Using 2-Dimensional Difference Gel Electrophoresis to Characterize Molecular Mechanisms of Chemical Warfare Nerve Agent Exposure in the Rat Brain

DTIC Science & Technology

2010-11-01

minced finely with scissors, and transferred to a pre-cooled hand-held glass dounce homogenizer. The pestle was passed through the dounce until the...Nakajima, Sarin experiences in Japan : acute toxicity and long-term effects. Journal of the Neurological Sciences, 2006. 249(1): p. 76-85. 9. Shih, T.-M

76 FR 58038 - Notice of Inventory Completion: U.S. Department of the Interior, Bureau of Indian Affairs...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-19

... iron handle, 1 iron handle fragment, 1 iron bowl fragment, 2 iron keys, 1 iron hinge, 1 iron gun hammer, 2 iron gun pieces, 1 fish hook, 12 nails, 1 iron ring, 1 coffee mill, 1 possible iron file, 1 large iron tack, 4 iron rods, 3 unidentified iron fragments, 1 metal tube, 1 scissors fragment, 1 finial...

Buns, Scissors and Strawberry Laces--A Model of Science Education?

ERIC Educational Resources Information Center

Walsh, Ed; Edwards, Rebecca

2009-01-01

Models are included in the science National Curriculum because modelling is a key tool for scientists and an integral part of how science works. Modelling is explicitly referred to in the Programmes of Study for Science at Key Stage 3 and 4 (age 11-16) and in Assessing Pupil's Progress (APP). Pupils need to learn how to use models because they are…

Asteroseismology can reveal strong internal magnetic fields in red giant stars.

PubMed

Fuller, Jim; Cantiello, Matteo; Stello, Dennis; Garcia, Rafael A; Bildsten, Lars

2015-10-23

Internal stellar magnetic fields are inaccessible to direct observations, and little is known about their amplitude, geometry, and evolution. We demonstrate that strong magnetic fields in the cores of red giant stars can be identified with asteroseismology. The fields can manifest themselves via depressed dipole stellar oscillation modes, arising from a magnetic greenhouse effect that scatters and traps oscillation-mode energy within the core of the star. The Kepler satellite has observed a few dozen red giants with depressed dipole modes, which we interpret as stars with strongly magnetized cores. We find that field strengths larger than ~10(5) gauss may produce the observed depression, and in one case we infer a minimum core field strength of ≈10(7) gauss. Copyright © 2015, American Association for the Advancement of Science.

The Development of Object Function and Manipulation Knowledge: Evidence from a Semantic Priming Study

PubMed Central

Collette, Cynthia; Bonnotte, Isabelle; Jacquemont, Charlotte; Kalénine, Solène; Bartolo, Angela

2016-01-01

Object semantics include object function and manipulation knowledge. Function knowledge refers to the goal attainable by using an object (e.g., the function of a key is to open or close a door) while manipulation knowledge refers to gestures one has to execute to use an object appropriately (e.g., a key is held between the thumb and the index, inserted into the door lock and then turned). To date, several studies have assessed function and manipulation knowledge in brain lesion patients as well as in healthy adult populations. In patients with left brain damage, a double dissociation between these two types of knowledge has been reported; on the other hand, behavioral studies in healthy adults show that function knowledge is processed faster than manipulation knowledge. Empirical evidence has shown that object interaction in children differs from that in adults, suggesting that the access to function and manipulation knowledge in children might also differ. To investigate the development of object function and manipulation knowledge, 51 typically developing 8-9-10 year-old children and 17 healthy young adults were tested on a naming task associated with a semantic priming paradigm (190-ms SOA; prime duration: 90 ms) in which a series of line drawings of manipulable objects were used. Target objects could be preceded by three priming contexts: related (e.g., knife-scissors for function; key-screwdriver for manipulation), unrelated but visually similar (e.g., glasses-scissors; baseball bat-screwdriver), and purely unrelated (e.g., die-scissors; tissue-screwdriver). Results showed a different developmental pattern of function and manipulation priming effects. Function priming effects were not present in children and emerged only in adults, with faster naming responses for targets preceded by objects sharing the same function. In contrast, manipulation priming effects were already present in 8-year-olds with faster naming responses for targets preceded by objects sharing the same manipulation and these decreased linearly between 8 and 10 years of age, 10-year-olds not differing from adults. Overall, results show that the access to object function and manipulation knowledge changes during development by favoring manipulation knowledge in childhood and function knowledge in adulthood. PMID:27602004

Scale effects in the response and failure of fiber reinforced composite laminates loaded in tension and in flexure

NASA Technical Reports Server (NTRS)

Jackson, Karen E.; Kellas, Sotiris; Morton, John

1992-01-01

The feasibility of using scale model testing for predicting the full-scale behavior of flat composite coupons loaded in tension and beam-columns loaded in flexure is examined. Classical laws of similitude are applied to fabricate and test replica model specimens to identify scaling effects in the load response, strength, and mode of failure. Experiments were performed on graphite-epoxy composite specimens having different laminate stacking sequences and a range of scaled sizes. From the experiments it was deduced that the elastic response of scaled composite specimens was independent of size. However, a significant scale effect in strength was observed. In addition, a transition in failure mode was observed among scaled specimens of certain laminate stacking sequences. A Weibull statistical model and a fracture mechanics based model were applied to predict the strength scale effect since standard failure criteria cannot account for the influence of absolute specimen size on strength.

Failure of a laminated composite under tension-compression fatigue loading

NASA Technical Reports Server (NTRS)

Rotem, A.; Nelson, H. G.

1989-01-01

The fatigue behavior of composite laminates under tension-compression loading is analyzed and compared with behavior under tension-tension and compression-compression loading. It is shown that for meaningful fatigue conditions, the tension-compression case is the dominant one. Both tension and compression failure modes can occur under the reversed loading, and failure is dependent on the specific lay-up of the laminate and the difference between the tensile static strength and the absolute value of the compressive static strength. The use of a fatigue failure envelope for determining the fatigue life and mode of failure is proposed and demonstrated.

Catastrophic instabilities of modified DA-DC hybrid surface waves in a semi-bounded plasma system

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

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr

We find the catastrophic instabilities and derive the growth rates for the dust-cyclotron resonance (DCR) and dust-rotation resonance (DRR) modes of the modified dust-acoustic and dust-cyclotron (DA-DC) hybrid surface waves propagating at the plasma–vacuum interface where the plasma is semi-bounded and composed of electrons and rotating dust grains. The effects of magnetic field and dust rotation frequency on the DCR- and DDR-modes are also investigated. We find that the dust rotation frequency enhances the growth rate of DCR-mode and the effect of dust rotation on this resonance mode decreases with an increase of the wave number. We also find thatmore » an increase of magnetic field strength enhances the DCR growth rate, especially, for the short wavelength regime. In the case of DRR-mode, the growth rate is found to be decreased less sensitively with an increase of the wave number compared with the case of DCR, but much significantly enhanced by an increase of dust rotation frequency. The DRR growth rate also decreases with an increase of the magnetic field strength, especially in the long wavelength regime. Interestingly, we find that catastrophic instabilities occur for both DCR- and DRR-modes of the modified DA-DC hybrid surface waves when the rotational frequency is close to the dust-cyclotron frequency. Both modes can also be excited catastrophically due to the cooperative interaction between the DCR-mode and the DRR-mode.« less

Biomechanical measurements of stiffness and strength for five types of whole human and artificial humeri.

PubMed

Aziz, Mina S R; Nicayenzi, Bruce; Crookshank, Meghan C; Bougherara, Habiba; Schemitsch, Emil H; Zdero, Radovan

2014-05-01

The human humerus is the third largest longbone and experiences 2-3% of all fractures. Yet, almost no data exist on its intact biomechanical properties, thus preventing researchers from obtaining a full understanding of humerus behavior during injury and after being repaired with fracture plates and nails. The aim of this experimental study was to compare the biomechanical stiffness and strength of "gold standard" fresh-frozen humeri to a variety of humerus models. A series of five types of intact whole humeri were obtained: human fresh-frozen (n = 19); human embalmed (n = 18); human dried (n = 15); artificial "normal" (n = 12); and artificial "osteoporotic" (n = 12). Humeri were tested under "real world" clinical loading modes for shear stiffness, torsional stiffness, cantilever bending stiffness, and cantilever bending strength. After removing geometric effects, fresh-frozen results were 585.8 ± 181.5 N/mm2 (normalized shear stiffness); 3.1 ± 1.1 N/(mm2 deg) (normalized torsional stiffness); 850.8 ± 347.9 N/mm2 (normalized cantilever stiffness); and 8.3 ± 2.7 N/mm2 (normalized cantilever strength). Compared to fresh-frozen values, statistical equivalence (p ≥ 0.05) was obtained for all four test modes (embalmed humeri), 1 of 4 test modes (dried humeri), 1 of 4 test modes (artificial "normal" humeri), and 1 of 4 test modes (artificial "osteoporotic" humeri). Age and bone mineral density versus experimental results had Pearson linear correlations ranging from R = -0.57 to 0.80. About 77% of human humeri failed via a transverse or oblique distal shaft fracture, whilst 88% of artificial humeri failed with a mixed transverse + oblique fracture. To date, this is the most comprehensive study on the biomechanics of intact human and artificial humeri and can assist researchers to choose an alternate humerus model that can substitute for fresh-frozen humeri.

Modal energy analysis for mechanical systems excited by spatially correlated loads

NASA Astrophysics Data System (ADS)

Zhang, Peng; Fei, Qingguo; Li, Yanbin; Wu, Shaoqing; Chen, Qiang

2018-10-01

MODal ENergy Analysis (MODENA) is an energy-based method, which is proposed to deal with vibroacoustic problems. The performance of MODENA on the energy analysis of a mechanical system under spatially correlated excitation is investigated. A plate/cavity coupling system excited by a pressure field is studied in a numerical example, in which four kinds of pressure fields are involved, which include the purely random pressure field, the perfectly correlated pressure field, the incident diffuse field, and the turbulent boundary layer pressure fluctuation. The total energies of subsystems differ to reference solution only in the case of purely random pressure field and only for the non-excited subsystem (the cavity). A deeper analysis on the scale of modal energy is further conducted via another numerical example, in which two structural modes excited by correlated forces are coupled with one acoustic mode. A dimensionless correlation strength factor is proposed to determine the correlation strength between modal forces. Results show that the error on modal energy increases with the increment of the correlation strength factor. A criterion is proposed to establish a link between the error and the correlation strength factor. According to the criterion, the error is negligible when the correlation strength is weak, in this situation the correlation strength factor is less than a critical value.

Microtensile bond strength of etch and rinse versus self-etch adhesive systems.

PubMed

Hamouda, Ibrahim M; Samra, Nagia R; Badawi, Manal F

2011-04-01

The aim of this study was to compare the microtensile bond strength of the etch and rinse adhesive versus one-component or two-component self-etch adhesives. Twelve intact human molar teeth were cleaned and the occlusal enamel of the teeth was removed. The exposed dentin surfaces were polished and rinsed, and the adhesives were applied. A microhybride composite resin was applied to form specimens of 4 mm height and 6 mm diameter. The specimens were sectioned perpendicular to the adhesive interface to produce dentin-resin composite sticks, with an adhesive area of approximately 1.4 mm(2). The sticks were subjected to tensile loading until failure occurred. The debonded areas were examined with a scanning electron microscope to determine the site of failure. The results showed that the microtensile bond strength of the etch and rinse adhesive was higher than that of one-component or two-component self-etch adhesives. The scanning electron microscope examination of the dentin surfaces revealed adhesive and mixed modes of failure. The adhesive mode of failure occurred at the adhesive/dentin interface, while the mixed mode of failure occurred partially in the composite and partially at the adhesive/dentin interface. It was concluded that the etch and rinse adhesive had higher microtensile bond strength when compared to that of the self-etch adhesives. Copyright © 2010 Elsevier Ltd. All rights reserved.

Tailoring light-matter coupling in semiconductor and hybrid-plasmonic nanowires

PubMed Central

Piccione, Brian; Aspetti, Carlos O.; Cho, Chang-Hee; Agarwal, Ritesh

2014-01-01

Understanding interactions between light and matter is central to many fields, providing invaluable insights into the nature of matter. In its own right, a greater understanding of light-matter coupling has allowed for the creation of tailored applications, resulting in a variety of devices such as lasers, switches, sensors, modulators, and detectors. Reduction of optical mode volume is crucial to enhancing light-matter coupling strength, and among solid-state systems, self-assembled semiconductor and hybrid-plasmonic nanowires are amenable to creation of highly-confined optical modes. Following development of unique spectroscopic techniques designed for the nanowire morphology, carefully engineered semiconductor nanowire cavities have recently been tailored to enhance light-matter coupling strength in a manner previously seen in optical microcavities. Much smaller mode volumes in tailored hybrid-plasmonic nanowires have recently allowed for similar breakthroughs, resulting in sub-picosecond excited-state lifetimes and exceptionally high radiative rate enhancement. Here, we review literature on light-matter interactions in semiconductor and hybrid-plasmonic monolithic nanowire optical cavities to highlight recent progress made in tailoring light-matter coupling strengths. Beginning with a discussion of relevant concepts from optical physics, we will discuss how our knowledge of light-matter coupling has evolved with our ability to produce ever-shrinking optical mode volumes, shifting focus from bulk materials to optical microcavities, before moving on to recent results obtained from semiconducting nanowires. PMID:25093385

76 FR 53324 - Airworthiness Directives; Agusta S.p.A. Model A109A, A109A II, A109C, and A109K2 Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-26

... Airworthiness Directives; Agusta S.p.A. Model A109A, A109A II, A109C, and A109K2 Helicopters AGENCY: Federal... helicopters. That EAD currently requires inspecting the main rotor scissor fitting assembly to determine if... helicopter. DATES: Effective September 12, 2011. The incorporation by reference of certain publications...

Development of a puller-buncher for harvesting southern pines without taproot attached

Treesearch

Peter Koch; S.J. Coughran

1975-01-01

A harvester-buncher that mounts on the front of a wheeled skidder has been developed to pull entire pine trees from the ground like carrots. Two elements are central to its design. The first is a scissor-type grib equipped with a pair of sout horizontal knife blades that close at the groundline and bite several inches into the stem from oposite sides of the tre. The...

Development of a puller-buncher for harvesting southern pines with taproot attached

Treesearch

P. Koch; S.J. Coughran

1975-01-01

A harvester-buncher that mounts on the front of a wheeled skidder has been developed to pull entire pine trees from the ground like carrots. Two elements are central to its design. The first is a scissors-type grip equipped with a pair of stout horizontal knife blades that close at the groundline and bite several inches into the stem from opposite sides of the tree....

C{sub 60} AS A PROBE FOR ASTROPHYSICAL ENVIRONMENTS

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

Brieva, A. C.; Jäger, C.; Huisken, F.

2016-08-01

The C{sub 60} molecule has been recently detected in a wide range of astrophysical environments through its four active intramolecular vibrational modes ( T {sub 1u}) near 18.9, 17.4, 8.5, and 7.0 μ m. The strengths of the mid-infrared emission bands have been used to infer astrophysical conditions in the fullerene-rich regions. Widely varying values of the relative intrinsic strengths (RIS) of these four bands are reported in laboratory and theoretical papers, which impedes the derivation of the excitation mechanism of C{sub 60} in the astrophysical sources. The spectroscopic analysis of the C{sub 60} samples produced with our method deliversmore » highly reproducible RIS values of 100, 25 ± 1, 26 ± 1 and 40 ± 4. A comparison of the inferred C{sub 60} emission band strengths with the astrophysical data shows that the observed strengths cannot be explained in terms of fluorescent or thermal emission alone. The large range in the observed 17.4 μ m/18.9 μ m emission ratios indicates that either the emission bands contain significant contributions from emitters other than C{sub 60}, or that the population distribution among the C{sub 60} vibrational modes is affected by physical processes other than thermal or UV excitation, such as chemo-luminescence from nascent C{sub 60} or possibly Poincaré fluorescence resulting from an inverse internal energy conversion. We have carefully analyzed the effect of the weakly active fundamental modes and second order modes in the mid-infrared spectrum of C{sub 60}, and propose that neutral C{sub 60} is the carrier of the unidentified emission band at 6.49 μ m which has been observed in fullerene-rich environments.« less

Use of graph algorithms in the processing and analysis of images with focus on the biomedical data.

PubMed

Zdimalova, M; Roznovjak, R; Weismann, P; El Falougy, H; Kubikova, E

2017-01-01

Image segmentation is a known problem in the field of image processing. A great number of methods based on different approaches to this issue was created. One of these approaches utilizes the findings of the graph theory. Our work focuses on segmentation using shortest paths in a graph. Specifically, we deal with methods of "Intelligent Scissors," which use Dijkstra's algorithm to find the shortest paths. We created a new software in Microsoft Visual Studio 2013 integrated development environment Visual C++ in the language C++/CLI. We created a format application with a graphical users development environment for system Windows, with using the platform .Net (version 4.5). The program was used for handling and processing the original medical data. The major disadvantage of the method of "Intelligent Scissors" is the computational time length of Dijkstra's algorithm. However, after the implementation of a more efficient priority queue, this problem could be alleviated. The main advantage of this method we see in training that enables to adapt to a particular kind of edge, which we need to segment. The user involvement has a significant influence on the process of segmentation, which enormously aids to achieve high-quality results (Fig. 7, Ref. 13).

For AAPT: Teaching the Wave Mechanics of McLeods' Stringy Electron, Explicit Nucleons, and Through-the-Earth Projections of Constellations' Stick Figures

NASA Astrophysics Data System (ADS)

McLeod, David Matthew

2011-11-01

McLeods' NEF11#22 submission is from their same-title INVITED presentation at Frontiers in Optics 2011, San Jose, CA. It shows how Hooke's law for electron, proton and neutron strings build electromagnetic waves from strings. These are composed of spirally linked, parallel, north-pole oriented, neutrino and antineutrino strings, stable because of magnetic repulsions. Their Dumbo Proton is antineutrino-scissor cut, and compressed in the vicinity of a neutron star, where electrostatic marriage occurs with a neutrino-scissor cut, and compressed, electron, so a Mickey Neutron emerges. Strings then predict electron charge is -- 1/3 e, Dumbo P is 25 % longer than Mickey N, and Hooke says relaxing springs fuel three separate inflations after each Big Bang oscillation. Gravity can be strings longitudinally linked. Einstein says Herman Grid's black diagonals prove human vision reads its information from algebraically-signed electromagnetic field diffraction patterns known by ray-tracing, not difficult Spatial Fourier Transformation. High-schoolers understand its application to Wave Mechanics, and agree that positive-numbered probabilities do not enter to possibly displease God. Stick figure constellations detected, like Phoenix, Leo, Canis Major, and especially Orion, fool some observers into false beliefs in things like UFHumanoids, or Kokopelli, Pele and Pamola!

Acute optic nerve sheath fenestration in humans using the free electron laser (FEL): a case report

NASA Astrophysics Data System (ADS)

Joos, Karen M.; Mawn, Louise A.; Shen, Jin-Hui; Jansen, E. Duco; Casagrande, Vivien A.

2002-06-01

Our previous studies using rabbits and monkeys showed that the Amide II wavelength (6.45 micrometers ) produced by the FEL could efficiently produce an optic nerve sheath fenestration with minimal damage. In order to determine if the technology safely could be applied to human surgery, we used 2 blind human eyes during enucleation to compare the results of producing fenestrations with the FEL or a scissors. FDA and Vanderbilt IRB approvals, and individual patient consents were obtained. The FEL energy was transmitted to a human operating room. After disinsertion of the medial rectus muscle, an optic nerve sheath fenestration (2 mm diameter) was made with either the FEL (6.45 micrometers , 325 micrometers spot size, 30 Hz, 3 mJ) through a hollow waveguide surgical probe or with a scissors. The enucleation was then completed. The optic nerve was dissected from the globe and fixed. Specimens were examined histologically. Dural incisions were effective with both methods. FEL energy at 6.45 micrometers can be transmitted to an operating room and delivered to human ocular tissue through a hollow waveguide surgical probe. This FEL wavelength can produce an optic nerve sheath fenestration without acute direct damage to the nerve in this case report.

Behavioural and neural modulation of win-stay but not lose-shift strategies as a function of outcome value in Rock, Paper, Scissors.

PubMed

Forder, Lewis; Dyson, Benjamin James

2016-09-23

Competitive environments in which individuals compete for mutually-exclusive outcomes require rational decision making in order to maximize gains but often result in poor quality heuristics. Reasons for the greater reliance on lose-shift relative to win-stay behaviour shown in previous studies were explored using the game of Rock, Paper, Scissors and by manipulating the value of winning and losing. Decision-making following a loss was characterized as relatively fast and relatively inflexible both in terms of the failure to modulate the magnitude of lose-shift strategy and the lack of significant neural modulation. In contrast, decision-making following a win was characterized as relatively slow and relatively flexible both in terms of a behavioural increase in the magnitude of win-stay strategy and a neural modulation of feedback-related negativity (FRN) and stimulus-preceding negativity (SPN) following outcome value modulation. The win-stay/lose-shift heuristic appears not to be a unified mechanism, with the former relying on System 2 processes and the latter relying on System 1 processes. Our ability to play rationally appears more likely when the outcome is positive and when the value of wins are low, highlighting how vulnerable we can be when trying to succeed during competition.

Competitive intransitivity, population interaction structure, and strategy coexistence.

PubMed

Laird, Robert A; Schamp, Brandon S

2015-01-21

Intransitive competition occurs when competing strategies cannot be listed in a hierarchy, but rather form loops-as in the game rock-paper-scissors. Due to its cyclic competitive replacement, competitive intransitivity promotes strategy coexistence, both in rock-paper-scissors and in higher-richness communities. Previous work has shown that this intransitivity-mediated coexistence is strongly influenced by spatially explicit interactions, compared to when populations are well mixed. Here, we extend and broaden this line of research and examine the impact on coexistence of intransitive competition taking place on a continuum of small-world networks linking spatial lattices and regular random graphs. We use simulations to show that the positive effect of competitive intransitivity on strategy coexistence holds when competition occurs on networks toward the spatial end of the continuum. However, in networks that are sufficiently disordered, increasingly violent fluctuations in strategy frequencies can lead to extinctions and the prevalence of monocultures. We further show that the degree of disorder that leads to the transition between these two regimes is positively dependent on population size; indeed for very large populations, intransitivity-mediated strategy coexistence may even be possible in regular graphs with completely random connections. Our results emphasize the importance of interaction structure in determining strategy dynamics and diversity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Localized fluid discharge in subduction zones: Insights from tension veins around an ancient megasplay fault (Nobeoka Thrust, SW Japan)

NASA Astrophysics Data System (ADS)

Otsubo, M.; Hardebeck, J.; Miyakawa, A.; Yamaguchi, A.; Kimura, G.

2017-12-01

Fluid-rock interactions along seismogenic faults are of great importance to understand fault mechanics. The fluid loss by the formation of mode I cracks (tension cracks) increases the fault strength and creates drainage asperities along the plate interface (Sibson, 2013, Tectonophysics). The Nobeoka Thrust, in southwestern Japan, is an on-land example of an ancient megasplay fault and provides an excellent record of deformation and fluid flow at seismogenic depths of a subduction zone (Kondo et al., 2005, Tectonics). We focus on (1) Pore fluid pressure loss, (2) Amount of fault strength recovery, and (3) Fluid circulation by the formation of mode I cracks in the post-seismic period around the fault zone of the Nobeoka Thrust. Many quartz veins that filled mode I crack at the coastal outcrops suggest a normal faulting stress regime after faulting of the Nobeoka Thrust (Otsubo et al., 2016, Island Arc). We estimated the decrease of the pore fluid pressure by the formation of the mode I cracks around the Nobeoka Thrust in the post-seismic period. When the pore fluid pressure exceeds σ3, veins filling mode I cracks are constructed (Jolly and Sanderson, 1997, Jour. Struct. Geol.). We call the pore fluid pressure that exceeds σ3 "pore fluid over pressure". The differential stress in the post-seismic period and the driving pore fluid pressure ratio P* (P* = (Pf - σ3) / (σ1 - σ3), Pf: pore fluid pressure) are parameters to estimate the pore fluid over pressure. In the case of the Nobeoka Thrust (P* = 0.4, Otsubo et al., 2016, Island Arc), the pore fluid over pressure is up to 20 MPa (assuming tensile strength = 10 MPa). 20 MPa is equivalent to <10% of the total pore fluid pressure around the Nobeoka Thrust (depth = 10 km, density = 2.7 kg/m3). When the pore fluid pressure decreases by 4%, the normalized pore pressure ratio λ* (λ* = (Pf - Ph) / (Pl - Ph), Pl: lithostatic pressure; Ph: hydrostatic pressure) changes from 0.95 to 0.86. In the case of the Nobeoka Thrust, the fault strength can increase by up to 10 MPa (assuming frictional coefficient = 0.6). 10 MPa is almost equivalent to the stress drop values in large trench type earthquakes. Hence, we suggest that the fluid loss caused by the formation of mode I cracks in the post-seismic period may play an important role by increasing frictional strength along the megasplay fault.

Fracture under combined modes in 4340 steel

NASA Technical Reports Server (NTRS)

Shah, R. C.

1974-01-01

An experimental investigation was conducted to study the interaction of combined modes of loading on crack instability in the presence of the opening and sliding modes of stress intensity factors, the opening and tearing modes of stress intensity factors, and all three modes of stress intensity factors. Through-cracked and surface-cracked flat and round specimens, and round notched bar specimens fabricated from high strength 4340 steel were used for the investigation. The results are evaluated to determine fracture criteria under the combined modes of stress intensity factors for the 4340 steel. These results are compared with the results of other investigators obtained for different materials.

Torsional Shear Strength Tests for Glass-Ceramic Joined Silicon Carbide

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

Ferraris, Monica; Ventrella, Andrea; Salvo, Milena

2014-03-17

A torsion test on hour-glass-shaped samples with a full joined or a ring-shaped joined area was chosen in this study to measure shear strength of glass-ceramic joined silicon carbide. Shear strength of about 100 MPa was measured for full joined SiC with fracture completely inside their joined area. Attempts to obtain this shear strength with a ring-shaped joined area failed due to mixed mode fractures. However, full joined and ring-shaped steel hour-glasses joined by a glass-ceramic gave the same shear strength, thus suggesting that this test measures shear strength of joined components only when their fracture is completely inside theirmore » joined area.« less

The Shear Strength and Fracture Behavior of Sn-Ag- xSb Solder Joints with Au/Ni-P/Cu UBM

NASA Astrophysics Data System (ADS)

Lee, Hwa-Teng; Hu, Shuen-Yuan; Hong, Ting-Fu; Chen, Yin-Fa

2008-06-01

This study investigates the effects of Sb addition on the shear strength and fracture behavior of Sn-Ag-based solders with Au/Ni-P/Cu underbump metallization (UBM) substrates. Sn-3Ag- xSb ternary alloy solder joints were prepared by adding 0 wt.% to 10 wt.% Sb to a Sn-3.5Ag alloy and joining them with Au/Ni-P/Cu UBM substrates. The solder joints were isothermally stored at 150°C for up to 625 h to study their microstructure and interfacial reaction with the UBM. Single-lap shear tests were conducted to evaluate the mechanical properties, thermal resistance, and failure behavior. The results show that UBM effectively suppressed intermetallic compound (IMC) formation and growth during isothermal storage. The Sb addition helped to refine the Ag3Sn compounds, further improving the shear strength and thermal resistance of the solders. The fracture behavior evolved from solder mode toward the mixed mode and finally to the IMC mode with increasing added Sb and isothermal storage time. However, SnSb compounds were found in the solder with 10 wt.% Sb; they may cause mechanical degradation of the solder after long-term isothermal storage.

Predator–prey interactions mediated by prey personality and predator hunting mode

PubMed Central

Belgrad, Benjamin A.; Griffen, Blaine D.

2016-01-01

Predator–prey interactions are important drivers in structuring ecological communities. However, despite widespread acknowledgement that individual behaviours and predator species regulate ecological processes, studies have yet to incorporate individual behavioural variations in a multipredator system. We quantified a prevalent predator avoidance behaviour to examine the simultaneous roles of prey personality and predator hunting mode in governing predator–prey interactions. Mud crabs, Panopeus herbstii, reduce their activity levels and increase their refuge use in the presence of predator cues. We measured mud crab mortality and consistent individual variations in the strength of this predator avoidance behaviour in the presence of predatory blue crabs, Callinectes sapidus, and toadfish, Opsanus tau. We found that prey personality and predator species significantly interacted to affect mortality with blue crabs primarily consuming bold mud crabs and toadfish preferentially selecting shy crabs. Additionally, the strength of the predator avoidance behaviour depended upon the predation risk from the predator species. Consequently, the personality composition of populations and predator hunting mode may be valuable predictors of both direct and indirect predator–prey interaction strength. These findings support theories postulating mechanisms for maintaining intraspecies diversity and have broad implications for community dynamics. PMID:27075257

Predator-prey interactions mediated by prey personality and predator hunting mode.

PubMed

Belgrad, Benjamin A; Griffen, Blaine D

2016-04-13

Predator-prey interactions are important drivers in structuring ecological communities. However, despite widespread acknowledgement that individual behaviours and predator species regulate ecological processes, studies have yet to incorporate individual behavioural variations in a multipredator system. We quantified a prevalent predator avoidance behaviour to examine the simultaneous roles of prey personality and predator hunting mode in governing predator-prey interactions. Mud crabs, Panopeus herbstii, reduce their activity levels and increase their refuge use in the presence of predator cues. We measured mud crab mortality and consistent individual variations in the strength of this predator avoidance behaviour in the presence of predatory blue crabs, Callinectes sapidus, and toadfish, Opsanus tau We found that prey personality and predator species significantly interacted to affect mortality with blue crabs primarily consuming bold mud crabs and toadfish preferentially selecting shy crabs. Additionally, the strength of the predator avoidance behaviour depended upon the predation risk from the predator species. Consequently, the personality composition of populations and predator hunting mode may be valuable predictors of both direct and indirect predator-prey interaction strength. These findings support theories postulating mechanisms for maintaining intraspecies diversity and have broad implications for community dynamics. © 2016 The Author(s).

Rapid repair of severely earthquake-damaged bridge piers with flexural-shear failure mode

NASA Astrophysics Data System (ADS)

Sun, Zhiguo; Wang, Dongsheng; Du, Xiuli; Si, Bingjun

2011-12-01

An experimental study was conducted to investigate the feasibility of a proposed rapid repair technique for severely earthquake-damaged bridge piers with flexural-shear failure mode. Six circular pier specimens were first tested to severe damage in flexural-shear mode and repaired using early-strength concrete with high-fluidity and carbon fiber reinforced polymers (CFRP). After about four days, the repaired specimens were tested to failure again. The seismic behavior of the repaired specimens was evaluated and compared to the original specimens. Test results indicate that the proposed repair technique is highly effective. Both shear strength and lateral displacement of the repaired piers increased when compared to the original specimens, and the failure mechanism of the piers shifted from flexural-shear failure to ductile flexural failure. Finally, a simple design model based on the Seible formulation for post-earthquake repair design was compared to the experimental results. It is concluded that the design equation for bridge pier strengthening before an earthquake could be applicable to seismic repairs after an earthquake if the shear strength contribution of the spiral bars in the repaired piers is disregarded and 1.5 times more FRP sheets is provided.

Physical scales in the Wigner–Boltzmann equation

PubMed Central

Nedjalkov, M.; Selberherr, S.; Ferry, D.K.; Vasileska, D.; Dollfus, P.; Querlioz, D.; Dimov, I.; Schwaha, P.

2013-01-01

The Wigner–Boltzmann equation provides the Wigner single particle theory with interactions with bosonic degrees of freedom associated with harmonic oscillators, such as phonons in solids. Quantum evolution is an interplay of two transport modes, corresponding to the common coherent particle-potential processes, or to the decoherence causing scattering due to the oscillators. Which evolution mode will dominate depends on the scales of the involved physical quantities. A dimensionless formulation of the Wigner–Boltzmann equation is obtained, where these scales appear as dimensionless strength parameters. A notion called scaling theorem is derived, linking the strength parameters to the coupling with the oscillators. It is shown that an increase of this coupling is equivalent to a reduction of both the strength of the electric potential, and the coherence length. Secondly, the existence of classes of physically different, but mathematically equivalent setups of the Wigner–Boltzmann evolution is demonstrated. PMID:23504194

The effects of magnetic field in plume region on the performance of multi-cusped field thruster

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

Hu, Peng, E-mail: hupengemail@126.com; Liu, Hui, E-mail: thruster@126.com; Yu, Daren

2015-10-15

The performance characteristics of a Multi-cusped Field Thruster depending on the magnetic field in the plume region were investigated. Five magnetic field shielding rings were separately mounted near the exit of discharge channel to decrease the strength of magnetic field in the plume region in different levels, while the magnetic field in the upstream was well maintained. The test results show that the electron current increases with the decrease of magnetic field strength in the plume region, which gives rise to higher propellant utilization and lower current utilization. On the other hand, the stronger magnetic field in the plume regionmore » improves the performance at low voltages (high current mode) while lower magnetic field improves the performance at high voltages (low current mode). This work can provide some optimal design ideas of the magnetic strength in the plume region to improve the performance of thruster.« less

Fracture resistance and fatigue crack growth characteristics of two Al-Cu-Mg-Zr alloys

NASA Technical Reports Server (NTRS)

Sarkar, Bhaskar; Lisagor, W. B.

1992-01-01

The dependence of strength, fracture resistance, and fatigue crack growth rate on the aging conditions of two alloy compositions based on Al-3.7Cu-1.85Mg-0.2Mn is investigated. Mechanical properties were evaluated in two heat treatment conditions and in two orientations (longitudinal and transverse). Compact tension specimens were used to determine fatigue crack growth characteristics and fracture resistance. The aging response was monitored on coupons using hardness measurements determined with a standard Rockwell hardness tester. Fracture resistance is found to increase with increasing yield strength during artificial aging of age-hardenable 2124-Zr alloys processed by powder metallurgy techniques. Fatigue crack growth rate increases with increasing strength. It is argued that these changes are related to deformation modes of the alloys; a homogeneous deformation mode tends to increase fracture resistance and to decrease the resistance to the fatigue crack propagation rate.

Survival behavior in the cyclic Lotka-Volterra model with a randomly switching reaction rate

NASA Astrophysics Data System (ADS)

West, Robert; Mobilia, Mauro; Rucklidge, Alastair M.

2018-02-01

We study the influence of a randomly switching reproduction-predation rate on the survival behavior of the nonspatial cyclic Lotka-Volterra model, also known as the zero-sum rock-paper-scissors game, used to metaphorically describe the cyclic competition between three species. In large and finite populations, demographic fluctuations (internal noise) drive two species to extinction in a finite time, while the species with the smallest reproduction-predation rate is the most likely to be the surviving one (law of the weakest). Here we model environmental (external) noise by assuming that the reproduction-predation rate of the strongest species (the fastest to reproduce and predate) in a given static environment randomly switches between two values corresponding to more and less favorable external conditions. We study the joint effect of environmental and demographic noise on the species survival probabilities and on the mean extinction time. In particular, we investigate whether the survival probabilities follow the law of the weakest and analyze their dependence on the external noise intensity and switching rate. Remarkably, when, on average, there is a finite number of switches prior to extinction, the survival probability of the predator of the species whose reaction rate switches typically varies nonmonotonically with the external noise intensity (with optimal survival about a critical noise strength). We also outline the relationship with the case where all reaction rates switch on markedly different time scales.

Pilot Fullerton prepares meal on middeck

NASA Image and Video Library

1982-03-30

STS003-26-253 (30 March 1982) --- Astronaut Gordon Fullerton, STS-3 pilot, wearing communications kit assembly (assy) mini-headset (HDST), prepares meal on middeck. Fullerton clips corner of rehydratable food (cereal) package with scissors. The opening will allow Fullerton to insert JSC water dispenser kit water gun in order to heat contents with hot water. Meal tray assembly is secured to forward middeck locker and holds additional food packages and beverage containers. Photo credit: NASA

Close-up locker scene of material belonging to Payload specialist Neri

NASA Technical Reports Server (NTRS)

1985-01-01

Close-up locker scene of materials belonging to Payload specialist Rodolfo Neri. Items include a Morelos satellite decal, the crest of the Universidad Nacional Autonoma de Mexico (Neri's alma mater), and one of the plant experiments he monitored during the flight. The experiment at bottom frame is the Transportation of Nutrients in a Weightless Environment (TRANSPORT). A pair of scissors are on the locker and a pen floats above it.

Astronaut Jerry Linenger with sheet of TIPS correspondence

NASA Image and Video Library

1994-09-15

STS064-23-025 (9-20 Sept. 1994) --- With scissors in hand, astronaut Jerry M. Linenger, STS-64 mission specialist, prepares to cut off a lengthy sheet of correspondence from ground controllers. Called the Thermal Imaging Printing System (TIPS), the message center occupies a stowage locker on the space shuttle Discovery's middeck. Astronaut L. Blaine Hammond, pilot, retrieves a clothing item from a nearby locker. Photo credit: NASA or National Aeronautics and Space Administration

Bioengineered Skin From Stem Cells for Treatment of Cutaneous Vesicant Injury

DTIC Science & Technology

2006-11-01

sterile gauze; the gauze was dipped into the decontamination solution using forceps and gently applied to the injury site using circular motions...weight ratio of the skin biopsy of the animals exposed to CEES and treated with either bioengineered skin or saline. Briefly, at different time...The CEES + saline or CEES + bioengineered skin treated areas were excised using a sterile blade, scissors, and forceps . Half of the skin sample

Ki-67 Expression in Human Tumors Measured by Flow Cytometry

DTIC Science & Technology

1990-01-01

Analyzed Fresh tissues obtained from the lymph node biopsies of 30 patients diagnosed as having non-Hodgkin’s lymphoma, nine biopsies identified as...breast tumors, and eight biopsies identified as colon tumors were included in this study. Cell Lines K562 Cell Line The human ervthroleukemia cell line...petri dish. While holding the tissue with toothed forceps , it wa,-is minced with scissors. Ujsing at transfer pip:., tissue fragments we re aspirated

Block by Block: The Challenges of Urban Operations

DTIC Science & Technology

2003-01-01

So the game of measures and coun- termeasures—the adult, and much more deadly, version of the familiar children’s game of rock, scissors, paper—has...January 1995 that, even when badly outmanned and outequipped, the city offered them unique advantages— familiarity with the terrain, the element of... familiar with the conditions of urban fighting was Ratko Mladiæ. He later emerged as the overall Bosnian Serb commander at Sarajevo. Third, the

Estimation of polymer-surface interfacial interaction strength by a contact AFM technique.

PubMed

Dvir, H; Jopp, J; Gottlieb, M

2006-12-01

Atomic force microscopy (AFM) measurements were employed to assess polymer-surface interfacial interaction strength. The main feature of the measurement is the use of contact-mode AFM as a tool to scratch off the polymer monolayer adsorbed on the solid surface. Tapping-mode AFM was used to determine the depth of the scraped recess. Independent determination of the layer thickness obtained from optical phase interference microscopy (OPIM) confirmed the depth of the AFM scratch. The force required for the complete removal of the polymer layer with no apparent damage to the substrate surface was determined. Polypropylene (PP), low-density polyethylene (PE), and PP-grafted-maleic anhydride (PP-g-ma) were scraped off silane-treated glass slabs, and the strength of surface interaction of the polymer layer was determined. In all cases it was determined that the magnitude of surface interaction force is of the order of van der Waals (VDW) interactions. The interaction strength is influenced either by polymer ability to wet the surface (hydrophobic or hydrophilic interactions) or by hydrogen bonding between the polymer and the surface treatment.

Cannabis, cigarettes, and their co-occurring use: disentangling differences in default mode network functional connectivity

PubMed Central

Wetherill, Reagan R.; Fang, Zhuo; Jagannathan, Kanchana; Childress, Anna Rose; Rao, Hengyi; Franklin, Teresa R.

2015-01-01

Background Resting-state functional connectivity is a noninvasive, neuroimaging method for assessing neural network function. Altered functional connectivity among regions of the default-mode network have been associated with both nicotine and cannabis use; however, less is known about co-occurring cannabis and tobacco use. Methods We used posterior cingulate cortex (PCC) seed-based resting-state functional connectivity analyses to examine default mode network (DMN) connectivity strength differences between four groups: 1) individuals diagnosed with cannabis dependence who do not smoke tobacco (n=19; ages 20–50), 2) cannabis-dependent individuals who smoke tobacco (n=23, ages 21–52), 3) cannabis-naïve, nicotine-dependent individuals who smoke tobacco (n=24, ages 21–57), and 4) cannabis- and tobacco-naïve healthy controls (n=21, ages 21–50), controlling for age, sex, and alcohol use. We also explored associations between connectivity strength and measures of cannabis and tobacco use. Results PCC seed-based analyses identified the core nodes of the DMN (i.e., PCC, medial prefrontal cortex, inferior parietal cortex, and temporal cortex). In general, the cannabis-dependent, nicotine-dependent, and co-occurring use groups showed lower DMN connectivity strengths than controls, with unique group differences in connectivity strength between the PCC and the cerebellum, medial prefrontal cortex, parahippocampus, and anterior insula. In cannabis-dependent individuals, PCC-right anterior insula connectivity strength correlated with duration of cannabis use. Conclusions This study extends previous research that independently examined the differences in resting-state functional connectivity among individuals who smoke cannabis and tobacco by including an examination of co-occurring cannabis and tobacco use and provides further evidence that cannabis and tobacco exposure is associated with alterations in DMN connectivity. PMID:26094186

Less-invasive stabilization of rib fractures by intramedullary fixation: a biomechanical evaluation.

PubMed

Bottlang, Michael; Helzel, Inga; Long, William; Fitzpatrick, Daniel; Madey, Steven

2010-05-01

This study evaluated intramedullary fixation of rib fractures with Kirschner wires and novel ribs splints. We hypothesized that rib splints can provide equivalent fixation strength while avoiding complications associated with Kirschner wires, namely wire migration and cutout. The durability, strength, and failure modes of rib fracture fixation with Kirschner wires and rib splints were evaluated in 22 paired human ribs. First, intact ribs were loaded to failure to determine their strength. After fracture fixation with Kirschner wires and rib splints, fixation constructs were dynamically loaded to 360,000 cycles at five times the respiratory load to determine their durability. Finally, constructs were loaded to failure to determine residual strength and failure modes. All constructs sustained dynamic loading without failure. Dynamic loading caused three times more subsidence in Kirschner wire constructs (1.2 mm +/- 1.4 mm) than in rib splint constructs (0.4 mm +/- 0.2 mm, p = 0.09). After dynamic loading, rib splint constructs remained 48% stronger than Kirschner wire constructs (p = 0.001). Five of 11 Kirschner wire constructs failed catastrophically by cutting through the medial cortex, leading to complete loss of stability and wire migration through the lateral cortex. The remaining six constructs failed by wire bending. Rib splint constructs failed by development of fracture lines along the superior and interior cortices. No splint construct failed catastrophically, and all splint constructs retained functional reduction and fixation. Because of their superior strength and absence of catastrophic failure mode, rib splints can serve as an attractive alternative to Kirschner wires for intramedullary stabilization of rib fractures, especially in the case of posterior rib fractures where access for plating is limited.

Shear Bond Strength of Orthodontic Brackets Bonded to Zirconium Crowns

PubMed Central

Mehmeti, Blerim; Azizi, Bleron; Kelmendi, Jeta; Iljazi-Shahiqi, Donika; Alar, Željko

2017-01-01

Background An increasing demand for esthetic restorations has resulted in an increased use of all-ceramic restorations, such as zirconium. However, one of the challenges the orthodontist must be willing to face is how to increase bond strength between the brackets and various ceramic restorations.Bond strength can beaffected bybracket type, by the material that bracketsaremade of, and their base surface design or retention mode. ​ Aim: of this study was to perform a comparative analysis of the shear bond strength (SBS) of metallic and ceramic orthodontic brackets bonded to all-zirconium ceramic surfaces used for prosthetic restorations, and also to evaluate the fracture mode of these two types of orthodontic brackets. Material and methods Twenty samples/semi-crowns of all-zirconium ceramic, on which orthodontic brackets were bonded, 10 metallic and 10 ceramic polycrystalline brackets, were prepared for this research. SBS has been testedby Universal Testing Machine, with a load applied using a knife edged rod moving at a fixed rate of 1 mm/min, until failure occurred. The force required to debond the brackets was recorded in Newton, then SBS was calculated to MPa. In addition, the samples were analyzed using a digital camera magnifier to determine Adhesive Remnant Index (ARI). Statistical data were processed using t-test, and the level of significance was set at α = 0.05. Results Higher shear bond strength values were observed in metallic brackets bonded to zirconium crowns compared tothoseof ceramic brackets, with a significant difference. During the test, two of the ceramic brackets were partially or totally damaged. Conclusion Metallic brackets, compared to ceramic polycrystalline brackets, seemed tocreate stronger adhesion with all-zirconium surfaces due to their better retention mode. Also, ceramic brackets showed higher fragility during debonding. PMID:28827846

Shear Bond Strength of Orthodontic Brackets Bonded to Zirconium Crowns.

PubMed

Mehmeti, Blerim; Azizi, Bleron; Kelmendi, Jeta; Iljazi-Shahiqi, Donika; Alar, Željko; Anić-Milošević, Sandra

2017-06-01

An increasing demand for esthetic restorations has resulted in an increased use of all-ceramic restorations, such as zirconium. However, one of the challenges the orthodontist must be willing to face is how to increase bond strength between the brackets and various ceramic restorations.Bond strength can beaffected bybracket type, by the material that bracketsaremade of, and their base surface design or retention mode. ​: A im: of this study was to perform a comparative analysis of the shear bond strength (SBS) of metallic and ceramic orthodontic brackets bonded to all-zirconium ceramic surfaces used for prosthetic restorations, and also to evaluate the fracture mode of these two types of orthodontic brackets. Twenty samples/semi-crowns of all-zirconium ceramic, on which orthodontic brackets were bonded, 10 metallic and 10 ceramic polycrystalline brackets, were prepared for this research. SBS has been testedby Universal Testing Machine, with a load applied using a knife edged rod moving at a fixed rate of 1 mm/min, until failure occurred. The force required to debond the brackets was recorded in Newton, then SBS was calculated to MPa. In addition, the samples were analyzed using a digital camera magnifier to determine Adhesive Remnant Index (ARI). Statistical data were processed using t-test, and the level of significance was set at α = 0.05. Higher shear bond strength values were observed in metallic brackets bonded to zirconium crowns compared tothoseof ceramic brackets, with a significant difference. During the test, two of the ceramic brackets were partially or totally damaged. Metallic brackets, compared to ceramic polycrystalline brackets, seemed tocreate stronger adhesion with all-zirconium surfaces due to their better retention mode. Also, ceramic brackets showed higher fragility during debonding.

Comparative in vitro evaluation of CAD/CAM vs conventional provisional crowns

PubMed Central

ABDULLAH, Adil Othman; TSITROU, Effrosyni A; POLLINGTON, Sarah

2016-01-01

ABSTRACT Objective This study compared the marginal gap, internal fit, fracture strength, and mode of fracture of CAD/CAM provisional crowns with that of direct provisional crowns. Material and Methods An upper right first premolar phantom tooth was prepared for full ceramic crown following tooth preparation guidelines. The materials tested were: VITA CAD-Temp®, Polyetheretherketone “PEEK”, Telio CAD-Temp, and Protemp™4 (control group). The crowns were divided into four groups (n=10), Group1: VITA CAD-Temp®, Group 2: PEEK, Group 3: Telio CAD-Temp, and Group 4: Protemp™4. Each crown was investigated for marginal and internal fit, fracture strength, and mode of fracture. Statistical analysis was performed using GraphPad Prism software version 6.0. Results The average marginal gap was: VITA CAD-Temp® 60.61 (±9.99) µm, PEEK 46.75 (±8.26) µm, Telio CAD-Temp 56.10 (±5.65) µm, and Protemp™4 193.07(±35.96) µm (P<0.001). The average internal fit was: VITA CAD-Temp® 124.94 (±22.96) µm, PEEK 113.14 (±23.55) µm, Telio CAD-Temp 110.95 (±11.64) µm, and Protemp™4 143.48(±26.74) µm. The average fracture strength was: VITA CAD-Temp® 361.01 (±21.61) N, PEEK 802.23 (±111.29) N, Telio CAD-Temp 719.24 (±95.17) N, and Protemp™4 416.40 (±69.14) N. One-way ANOVA test showed a statistically significant difference for marginal gap, internal gap, and fracture strength between all groups (p<0.001). However, the mode of fracture showed no differences between the groups (p>0.05). Conclusions CAD/CAM fabricated provisional crowns demonstrated superior fit and better strength than direct provisional crowns. PMID:27383707

Comparative in vitro evaluation of CAD/CAM vs conventional provisional crowns.

PubMed

Abdullah, Adil Othman; Tsitrou, Effrosyni A; Pollington, Sarah

2016-01-01

This study compared the marginal gap, internal fit, fracture strength, and mode of fracture of CAD/CAM provisional crowns with that of direct provisional crowns. An upper right first premolar phantom tooth was prepared for full ceramic crown following tooth preparation guidelines. The materials tested were: VITA CAD-Temp®, Polyetheretherketone "PEEK", Telio CAD-Temp, and Protemp™4 (control group). The crowns were divided into four groups (n=10), Group1: VITA CAD-Temp®, Group 2: PEEK, Group 3: Telio CAD-Temp, and Group 4: Protemp™4. Each crown was investigated for marginal and internal fit, fracture strength, and mode of fracture. Statistical analysis was performed using GraphPad Prism software version 6.0. The average marginal gap was: VITA CAD-Temp® 60.61 (±9.99) µm, PEEK 46.75 (±8.26) µm, Telio CAD-Temp 56.10 (±5.65) µm, and Protemp™4 193.07(±35.96) µm (P<0.001). The average internal fit was: VITA CAD-Temp® 124.94 (±22.96) µm, PEEK 113.14 (±23.55) µm, Telio CAD-Temp 110.95 (±11.64) µm, and Protemp™4 143.48(±26.74) µm. The average fracture strength was: VITA CAD-Temp® 361.01 (±21.61) N, PEEK 802.23 (±111.29) N, Telio CAD-Temp 719.24 (±95.17) N, and Protemp™4 416.40 (±69.14) N. One-way ANOVA test showed a statistically significant difference for marginal gap, internal gap, and fracture strength between all groups (p<0.001). However, the mode of fracture showed no differences between the groups (p>0.05). CAD/CAM fabricated provisional crowns demonstrated superior fit and better strength than direct provisional crowns.

Effectiveness of silica-lasing method on the bond strength of composite resin repair to Ni-Cr alloy.

PubMed

Madani, Azam S; Astaneh, Pedram Ansari; Nakhaei, Mohammadreza; Bagheri, Hossein G; Moosavi, Horieh; Alavi, Samin; Najjaran, Niloufar Tayarani

2015-04-01

The aim of this study was to evaluate the effectiveness of silica-lasing method for improving the composite resin repair of metal ceramic restorations. Sixty Ni-Cr cylindrical specimens were fabricated. The bonding surface of all specimens was airborne-particle abraded using 50 μm aluminum oxide particles. Specimens were divided into six groups that received the following surface treatments: group 1-airborne-particle abrasion alone (AA); group 2-Nd:YAG laser irradiation (LA); group 3-silica coating (Si-CO); group 4-silica-lasing (metal surface was coated with slurry of opaque porcelain and irradiated by Nd:YAG laser) (Si-LA); group 5-silica-lasing plus etching with HF acid (Si-LA-HF); group 6-CoJet sand lased (CJ-LA). Composite resin was applied on metal surfaces. Specimens were thermocycled and tested in shear mode in a universal testing machine. The shear bond strength values were analyzed using ANOVA and Tukey's tests (α = 0.05). The mode of failure was determined, and two specimens in each group were examined by scanning electron microscopy and wavelength dispersive X-ray spectroscopy. Si-CO showed significantly higher shear bond strength in comparison to other groups (p < 0.001). The shear bond strength values of the LA group were significantly higher than those of the AA group (p < 0.05). No significant difference was found among lased groups (LA, Si-LA, Si-LA-HF, CJ-LA; p > 0.05). The failure mode was 100% adhesive for AA, Si-LA, Si-LA-HF, and CJ-LA. LA and Si-CO groups showed 37.5% and 87.5% cohesive failure, respectively. Silica coating of Ni-Cr alloy resulted in higher shear bond strength than those of other surface treatments. © 2014 by the American College of Prosthodontists.

The effect of a ceramic coating on the cpTi-porcelain bond strength.

PubMed

Papadopoulos, Triantafillos D; Spyropoulos, Konstantin D

2009-02-01

To investigate the bond strength between cpTi and low fusing porcelains after different treatments. 72 patterns were covered with a ceramic coating and invested with phosphate-bonded material (group A), another 72 were invested with magnesia material (group B) and all cast with cpTi. 31 solid castings were selected from each group. The castings of group B were ground and sandblasted, while the castings of group A were only sandblasted. Aluminum content of the metal surface was determined by EDS and castings were submitted to a 3-point bending test to determine the modulus of elasticity (E). The porcelains Duceratin Plus, Noritake Ti22 and Triceram were applied respectively and specimens were submitted to a 3-point bending test. The fracture mode and the remaining porcelain were determined by optical microscopy and SEM/EDS. Bond strength and fracture mode were calculated by two-way ANOVA. The E of groups A and B was 98.3 GPa and 98.6 GPa respectively. The bond strength was 26+/-3 MPa (Duceratin Plus), 28+/-3 MPa (Noritake Ti22), 27+/-2 MPa (Triceram) for group A and 24+/-1 MPa, 29+/-2 MPa, 27+/-1 MPa for group B respectively. No significant differences were found for the same porcelain between the two groups (p<0.05). A significant difference was found between Duceratin Plus and Noritake Ti22, for group B (p<0.05). The mode of failure was mainly adhesive for all specimens. A significant reduction in aluminum was recorded in all subgroups. The special coating of patterns makes the Ti casting procedure inexpensive, without reducing the metal-ceramic bond strength.

Efficient Scheme for Perfect Collective Einstein-Podolsky-Rosen Steering

PubMed Central

Wang, M.; Gong, Q. H.; Ficek, Z.; He, Q. Y.

2015-01-01

A practical scheme for the demonstration of perfect one-sided device-independent quantum secret sharing is proposed. The scheme involves a three-mode optomechanical system in which a pair of independent cavity modes is driven by short laser pulses and interact with a movable mirror. We demonstrate that by tuning the laser frequency to the blue (anti-Stokes) sideband of the average frequency of the cavity modes, the modes become mutually coherent and then may collectively steer the mirror mode to a perfect Einstein-Podolsky-Rosen state. The scheme is shown to be experimentally feasible, it is robust against the frequency difference between the modes, mechanical thermal noise and damping, and coupling strengths of the cavity modes to the mirror. PMID:26212901

Numerical simulations of fast-axis instability of vector solitons in mode-locked fiber lasers.

PubMed

Du, Yueqing; Shu, Xuewen; Cheng, Peiyun

2017-01-23

We demonstrate the fast-axis instability in mode-locked fiber lasers numerically for the first time. We find that the energy of the fast mode will be transferred to the slow mode when the strong pump strength makes the soliton period short. A nearly linearly polarized vector soliton along the slow-axis could be generated under certain cavity parameters. The final polarization of the vector soliton is related to the initial polarization of the seed pulse. Two regimes of energy exchanging between the slow mode and the fast mode are explored and the direction of the energy flow between two modes depends on the phase difference. The dip-type sidebands are found to be intrinsic characteristics of the mode-locked fiber lasers under high pulse energy.

The effect of thermocycling on tensile bond strength of two soft liners.

PubMed

Geramipanah, Farideh; Ghandari, Masoumeh; Zeighami, Somayeh

2013-09-01

Failure of soft liners depends mostly on separation from the denture base resin; therefore measurement of the bond strength is very important. The purpose of this study was to compare the tensile bond strength of two soft liners (Acropars, Molloplast-B) to denture base resin before and after thermocycling. Twenty specimens fromeach of the two different soft liners were processed according to the manufacturer's instructions between two polymethyl methacrylate (PMMA) sheets. Ten specimens in each group were maintained in 37°C water for 24 hours and 10 were thermocycled (5000 cycles) among baths of 5° and 55°C. The tensile bond strength was measured using a universal testing machine at a crosshead speed of 5 mm/min. Mode of failure was determined with SEM (magnification ×30). Two-way ANOVA was used to analyze the data. The mean and standard deviation of tensile bond strength of Acropars and Molloplast-B before thermocycling were 6.59±1.85 and1.51±0.22 MPa, respectively and 5.89±1.52 and1.37±0.18 MPa, respectively after thermocycling. There was no significant difference before and after thermocycling. Mode of failure in Acropars and Molloplast-B were adhesive and cohesive, respectivley. The bond strength of Acropars was significantly higher than Molloplast-B (P<0.05).

Transverse Isotropy of Phyllite Under Brazilian Tests: Laboratory Testing and Numerical Simulations

NASA Astrophysics Data System (ADS)

Xu, Guowen; He, Chuan; Chen, Ziquan; Su, Ang

2018-04-01

Phyllite is a low-grade, metamorphic rock with well-developed foliation. We characterized the fracture pattern and failure strength of phyllite specimens under Brazilian tests. The specimens were obtained from the Zhegu mountain tunnel in China and had different foliation-loading angles, namely 0°, 15°, 30°, 45°, 60°, 75° and 90°. The processes for the initiation and propagation of macro-cracks were recorded using high-speed photography. The evolution of micro-cracks was analyzed based on the results of acoustic emission (AE) tests. The failure process of the specimens during the Brazilian tests was simulated with a new numerical approach based on the particle discrete element method. The influence of foliation strength and the microstructure of the rock matrix were also studied numerically. The experimental results showed that the failure strength of the specimens was related to their fracture patterns and the areas of their fracture surfaces. The initial cracking point of the specimens appeared at the upper or lower loading position, and the cracks propagated to the boundaries of the specimens along or across foliation. The temporal distributions of the AE counts and AE energy of the specimens were affected predominantly by the fracture pattern, and we divided these distributions into two modes: the peak mode and the uniformly distributed mode. The numerical results indicated that the fracture surface was roughly parallel to the loading direction and that the surface was located in the central part of the disk specimens for rocks with loose structure (low coordination number or large crack density) or with strong foliation, i.e., foliation with high shear strength. The failure pattern and trends of variation in failure strength as a function of foliation-loading angles varied with the ratio of cohesion to the tensile strength of foliation, the crack density, and the coordination number.

Dynamic deformation and fracture of single crystal silicon: Fracture modes, damage laws, and anisotropy

DOE PAGES

Huang, J. Y.; E, J. C.; Huang, J. W.; ...

2016-05-25

Impact fracture of single-crystal Si is critical to long-term reliability of electronic devices and solar cells for its wide use as components or substrates in semiconductor industry. Single-crystal Si is loaded along two different crystallographic directions with a split Hopkinson pressure bar integrated with an in situ x-ray imaging and diffraction system. Bulk stress histories are measured, simultaneously with x-ray phase contrast imaging (XPCI) and Laue diffraction. Damage evolution is quantified with grayscale maps from XPCI. Single-crystal Si exhibits pronounced anisotropy in fracture modes, and thus fracture strengths and damage evolution. For loading along [11¯ 0] and viewing along [001],more » (1¯1¯0)[11¯ 0] cleavage is activated and induces horizontal primary cracks followed by perpendicular wing cracks. However, for loading along [011¯] and viewing along [111], random nucleation and growth of shear and tensile-splitting crack networks lead to catastrophic failure of materials with no cleavage. The primary-wing crack mode leads to a lower characteristic fracture strength due to predamage, but a more concentrated strength distribution, i.e., a higher Weibull modulus, compared to the second loading case. Furthermore, the sequential primary cracking, wing cracking and wing-crack coalescence processes result in a gradual increase of damage with time, deviating from theoretical predictions. Particle size and aspect ratios of fragments are discussed with postmortem fragment analysis, which verifies fracture modes observed in XPCI.« less

Exact edge, bulk, and bound states of finite topological systems

NASA Astrophysics Data System (ADS)

Duncan, Callum W.; Öhberg, Patrik; Valiente, Manuel

2018-05-01

Finite topologically nontrivial systems are characterized, among many other unique properties, by the presence of bound states at their physical edges. These topological edge modes can be distinguished from usual Shockley waves energetically, as their energies remain finite and in gap even when the boundaries of the system represent an effectively infinite and sharp energetic barrier. Theoretically, the existence of topological edge modes can be shown by means of the bulk-edge correspondence and topological invariants. On a clean one-dimensional lattice and reducible two-dimensional models, in either the commensurate or semi-infinite case, the edge modes can be essentially obtained analytically, as shown previously [Y. Hatsugai, Phys. Rev. Lett. 71, 3697 (1993), 10.1103/PhysRevLett.71.3697; D. Hügel and B. Paredes, Phys. Rev. A 89, 023619 (2014), 10.1103/PhysRevA.89.023619]. In this work, we put forward a method for obtaining the spectrum and wave functions of topological edge modes for arbitrary finite lattices, including the incommensurate case. A small number of parameters are easily determined numerically, with the form of the eigenstates remaining fully analytical. We also obtain the bulk modes in the finite system analytically and their associated eigenenergies, which lie within the infinite-size limit continuum. Our method is general and can be easily applied to obtain the properties of nontopological models and/or extended to include impurities. As an example, we consider a relevant case of an impurity located next to one edge of a one-dimensional system, equivalent to a softened boundary in a separable two-dimensional model. We show that a localized impurity can have a drastic effect on the original topological edge modes of the system. Using the periodic Harper and Hofstadter models to illustrate our method, we find that, on increasing the impurity strength, edge states can enter or exit the continuum, and a trivial Shockley state bound to the impurity may appear. The fate of the topological edge modes in the presence of impurities can be addressed by quenching the impurity strength. We find that at certain critical impurity strengths, the transition probability for a particle initially prepared in an edge mode to decay into the bulk exhibits discontinuities that mark the entry and exit points of edge modes from and into the bulk spectrum.

Skeletal Strength and Skeletogenetic Mechanisms Over Phanerozoic Time

NASA Astrophysics Data System (ADS)

Constantz, B. R.

2004-12-01

Mineralized skeletons have a remarkable range of mechanical properties with respect to strength and durability. Measurements of skeletal mechanical properties show that taxonomic groups with relatively simple, `physiochemically-dominated' modes of mineralization possess skeletal strengths and durabilities that are among the lowest of any known mineralized skeletons. Organisms with relatively sophisticated, `biologically-dominated' modes of mineralization have mechanical properties among the highest values known for any materials. These extraordinarily strong and durable skeletal materials are found in mollusks, echinoderms, vertebrates, and arthropods, which are groups with primarily mobile ecological habits. These skeletons are frequently lightweight, non-massive skeletons with little phenotypic variation. By contrast, dominant reef framework builders and reef sediment formers, with physiochemically-dominated modes of mineralization, have non-mobile ecological habits and construct massive, phenotypically plastic skeletons, possessing extremely poor mechanical properties. Endolithic organisms that further degrade the mechanical properties of the mineralized skeletons of reef builders frequently ravage their massive skeletons. As a result, the skeletons of these groups commonly fragment, and play a central role in reef establishment and maintenance, as they are incorporated in reefal, wave-resistant carbonate buildups. Scleractinian corals have a physiochemically-dominated mode of mineralization and are the dominant modern reef framework builders. Mechanical properties of modern aragonitic scleractinian coral skeletons, tested alive, demonstrate skeletal strengths that are orders of magnitude lower than those seen in mollusks, echinoderms, vertebrates, and arthropods. Rudist bivalves, the dominant reef framework-building group of the Cretaceous, show prolific, massive, highly variable, calcific skeletal elements with structures similar to some reef-forming modern, non-mobile mollusks and the skeletons of other organisms with physiochemically-dominated modes of mineralization. Many aspects of the ecological habits of reef-framework building scleractinians and rudsits are similar, including relatively high skeletal growth rates, which produce massive skeletons and wave-resistant structures with entrapped bioclastic sediments. The principal adaptive role of mineralization in reef framework building groups appears to be the rapid production of massive, brittle, wave-resistant mineralized skeletons. The physiochemically-dominated mode of mineralization of these reef framework builders appears to have made them susceptible to secular variations in Phanerozoic seawater during `calcite' and `aragonite' seas, favoring scleractinians in aragonite seas and rudists during the Cretaceous calcite episode. By contrast, most mobile mollusks, echinoderms, vertebrates, and arthropods appear relatively unaffected by secular variations in seawater chemistry over the Phanerozoic

Effect of ozone gas on the shear bond strength to enamel

PubMed Central

PIRES, Patrícia Teixeira; FERREIRA, João Cardoso; OLIVEIRA, Sofia Arantes; SILVA, Mário Jorge; MELO, Paulo Ribeiro

2013-01-01

Ozone is an important disinfecting agent, however its influence on enamel adhesion has not yet been clarified. Objective: Evaluate the influence of ozone pretreatment on the shear strength of an etch-and-rinse and a self-etch system to enamel and analyze the respective failure modes. Material and Methods: Sixty sound bovine incisors were used. Specimens were randomly assigned to four experimental groups (n=15): Group G1 (Excite® with ozone) and group G3 (AdheSE® with ozone) were prepared with ozone gas from the HealOzone unit (Kavo®) for 20 s prior to adhesion, and groups G2 (Excite®) and G4 (AdheSE®) were used as control. Teeth were bisected and polished to simulate a smear layer just before the application of the adhesive systems. The adhesives were applied according to the manufacturer's instructions to a standardized 3 mm diameter surface, and a composite (Synergy D6, Coltene Whaledent) cylinder with 2 mm increments was build. Specimens were stored in 100% humidity for 24 h at 37º C and then subjected to a thermal cycling regimen of 500 cycles. Shear bond tests were performed with a Watanabe device in a universal testing machine at 5 mm/min. The failure mode was analyzed under scanning electron microscope. Means and standard deviation of shear bond strength (SBS) were calculated and difference between the groups was analyzed using ANOVA, Kolmogorov-Smirnov, Levene and Bonferroni. Chi-squared statistical tests were used to evaluate the failure modes. Results: Mean bond strength values and failure modes were as follows: G1- 26.85±6.18 MPa (33.3% of adhesive cohesive failure); G2 - 27.95±5.58 MPa (53.8% of adhesive failures between enamel and adhesive); G3 - 15.0±3.84 MPa (77.8% of adhesive failures between enamel and adhesive) and G4 - 13.1±3.68 MPa (36.4% of adhesive failures between enamel and adhesive). Conclusions: Shear bond strength values of both adhesives tested on enamel were not influenced by the previous application of ozone gas. PMID:23739859

Effect of ozone gas on the shear bond strength to enamel.

PubMed

Pires, Patrícia Teixeira; Ferreira, João Cardoso; Oliveira, Sofia Arantes; Silva, Mário Jorge; Melo, Paulo Ribeiro

2013-01-01

Ozone is an important disinfecting agent, however its influence on enamel adhesion has not yet been clarified. Evaluate the influence of ozone pretreatment on the shear strength of an etch-and-rinse and a self-etch system to enamel and analyze the respective failure modes. Sixty sound bovine incisors were used. Specimens were randomly assigned to four experimental groups (n=15): Group G1 (Excite® with ozone) and group G3 (AdheSE® with ozone) were prepared with ozone gas from the HealOzone unit (Kavo®) for 20 s prior to adhesion, and groups G2 (Excite®) and G4 (AdheSE®) were used as control. Teeth were bisected and polished to simulate a smear layer just before the application of the adhesive systems. The adhesives were applied according to the manufacturer's instructions to a standardized 3 mm diameter surface, and a composite (Synergy D6, Coltene Whaledent) cylinder with 2 mm increments was build. Specimens were stored in 100% humidity for 24 h at 37°C and then subjected to a thermal cycling regimen of 500 cycles. Shear bond tests were performed with a Watanabe device in a universal testing machine at 5 mm/min. The failure mode was analyzed under scanning electron microscope. Means and standard deviation of shear bond strength (SBS) were calculated and difference between the groups was analyzed using ANOVA, Kolmogorov-Smirnov, Levene and Bonferroni. Chi-squared statistical tests were used to evaluate the failure modes. Mean bond strength values and failure modes were as follows: G1--26.85±6.18 MPa (33.3% of adhesive cohesive failure); G2--27.95±5.58 MPa (53.8% of adhesive failures between enamel and adhesive); G3--15.0±3.84 MPa (77.8% of adhesive failures between enamel and adhesive) and G4--13.1±3.68 MPa (36.4% of adhesive failures between enamel and adhesive). Shear bond strength values of both adhesives tested on enamel were not influenced by the previous application of ozone gas.

Time- and temperature-dependent failures of a bonded joint

NASA Astrophysics Data System (ADS)

Sihn, Sangwook

This dissertation summarizes my study of time- and temperature-dependent behavior of a tubular lap bonded joint to provide a design methodology for windmill blade structures. The bonded joint is between a cast-iron rod and a GFRP composite pipe. The adhesive material is an epoxy containing chopped glass fibers. We proposed a new fabrication method to make concentric and void-less specimens of the tubular joint with a thick adhesive bondline to stimulate the root bond of a blade. The thick bondline facilitates the joint assembly of actual blades. For a better understanding of the behavior of the bonded joint, we studied viscoelastic behavior of the adhesive materials by measuring creep compliance at several temperatures during loading period. We observed that the creep compliance depends highly on the period of loading and the temperature. We applied time-temperature equivalence to the creep compliance of the adhesive material to obtain time-temperature shift factors. We also performed constant-rate of monotonically increased uniaxial tensile tests to measure static strength of the tubular lap joint at several temperatures and different strain-rates. We observed two failure modes from load-deflection curves and failed specimens. One is the brittle mode, which was caused by weakness of the interfacial strength occurring at low temperature and short period of loading. The other is the ductile mode, which was caused by weakness of the adhesive material at high temperature and long period of loading. Transition from the brittle to the ductile mode appeared as the temperature or the loading period increased. We also performed tests under uniaxial tensile-tensile cyclic loadings to measure fatigue strength of the bonded joint at several temperatures, frequencies and stress ratios. The fatigue data are analyzed statistically by applying the residual strength degradation model to calculate statistical distribution of the fatigue life. Combining the time-temperature equivalence and the residual strength degradation model enables us to estimate the fatigue life of the bonded joint at different load levels, frequencies and temperatures with a certain probability. A numerical example shows how to apply the life estimation method to a structure subjected to a random load history by rainflow cycle counting.

Stability and modal analysis of shock/boundary layer interactions

NASA Astrophysics Data System (ADS)

Nichols, Joseph W.; Larsson, Johan; Bernardini, Matteo; Pirozzoli, Sergio

2017-02-01

The dynamics of oblique shock wave/turbulent boundary layer interactions is analyzed by mining a large-eddy simulation (LES) database for various strengths of the incoming shock. The flow dynamics is first analyzed by means of dynamic mode decomposition (DMD), which highlights the simultaneous occurrence of two types of flow modes, namely a low-frequency type associated with breathing motion of the separation bubble, accompanied by flapping motion of the reflected shock, and a high-frequency type associated with the propagation of instability waves past the interaction zone. Global linear stability analysis performed on the mean LES flow fields yields a single unstable zero-frequency mode, plus a variety of marginally stable low-frequency modes whose stability margin decreases with the strength of the interaction. The least stable linear modes are grouped into two classes, one of which bears striking resemblance to the breathing mode recovered from DMD and another class associated with revolving motion within the separation bubble. The results of the modal and linear stability analysis support the notion that low-frequency dynamics is intrinsic to the interaction zone, but some continuous forcing from the upstream boundary layer may be required to keep the system near a limit cycle. This can be modeled as a weakly damped oscillator with forcing, as in the early empirical model by Plotkin (AIAA J 13:1036-1040, 1975).

Scissoring Fault Rupture Properties along the Median Tectonic Line Fault Zone, Southwest Japan

NASA Astrophysics Data System (ADS)

Ikeda, M.; Nishizaka, N.; Onishi, K.; Sakamoto, J.; Takahashi, K.

2017-12-01

The Median Tectonic Line fault zone (hereinafter MTLFZ) is the longest and most active fault zone in Japan. The MTLFZ is a 400-km-long trench parallel right-lateral strike-slip fault accommodating lateral slip components of the Philippine Sea plate oblique subduction beneath the Eurasian plate [Fitch, 1972; Yeats, 1996]. Complex fault geometry evolves along the MTLFZ. The geomorphic and geological characteristics show a remarkable change through the MTLFZ. Extensional step-overs and pull-apart basins and a pop-up structure develop in western and eastern parts of the MTLFZ, respectively. It is like a "scissoring fault properties". We can point out two main factors to form scissoring fault properties along the MTLFZ. One is a regional stress condition, and another is a preexisting fault. The direction of σ1 anticlockwise rotate from N170°E [Famin et al., 2014] in the eastern Shikoku to Kinki areas and N100°E [Research Group for Crustral Stress in Western Japan, 1980] in central Shikoku to N85°E [Onishi et al., 2016] in western Shikoku. According to the rotation of principal stress directions, the western and eastern parts of the MTLFZ are to be a transtension and compression regime, respectively. The MTLFZ formed as a terrain boundary at Cretaceous, and has evolved with a long active history. The fault style has changed variously, such as left-lateral, thrust, normal and right-lateral. Under the structural condition of a preexisting fault being, the rupture does not completely conform to Anderson's theory for a newly formed fault, as the theory would require either purely dip-slip motion on the 45° dipping fault or strike-slip motion on a vertical fault. The fault rupture of the 2013 Barochistan earthquake in Pakistan is a rare example of large strike-slip reactivation on a relatively low angle dipping fault (thrust fault), though many strike-slip faults have vertical plane generally [Avouac et al., 2014]. In this presentation, we, firstly, show deep subsurface structures of the MTLFZ based on newly obtained data and previous research results. And then, we discuss how the relationship between the surface fault geometry and the deep subsurface structures changes through the MTLFZ which is under the heterogeneous regional stress condition.

Surface topography and bond strengths of feldspathic porcelain prepared using various sandblasting pressures.

PubMed

Moravej-Salehi, Elham; Moravej-Salehi, Elahe; Valian, Azam

2016-11-01

The purpose of this study was to determine the bond strength of composite resin to feldspathic porcelain and its surface topography after sandblasting at different pressures. In this in vitro study, 68 porcelain disks were fabricated and randomly divided into four groups of 17. The porcelain surface in group 1 was etched with hydrofluoric acid. Groups 2, 3, and 4 were sandblasted at 2, 3 and 4 bars pressure, respectively. Surface topography of seven samples in each of the four groups was examined by a scanning electron microscope (SEM). The remaining 40 samples received the same silane agent, bonding agent, and composite resin and they were then subjected to 5000 thermal cycles and evaluated for shear bond strength. Data were analyzed using one-way anova. The mode of failure was determined using stereomicroscope and SEM. The highest shear bond strength was seen in group 4. however, statistically significant differences were not seen between the groups (P = 0.780). The most common mode of failure was cohesive in porcelain. The SEM showed different patterns of hydrofluoric acid etching and sandblasting. Increasing the sandblasting pressure increased the surface roughness of feldspathic porcelain but no difference in bond strength occurred. © 2015 Wiley Publishing Asia Pty Ltd.

A Wind Tunnel Investigation of Joined Wing Scissor Morphing

DTIC Science & Technology

2006-06-01

would use the low sweep for carrier landing and subsonic cruise, and use the high sweep for 12 supersonic flight [13]. According to Raymer [19...Wright-Patterson AFB, Ohio: Air Force Institute of Technology, 2005. 12. Katz, Joseph, Shaun Byrne, and Robert Hahl. "Stall Resistance Features of...Lifting-Body Airplane Configurations." Journal of Aircraft 2nd ser. 36 (1999): 471-474. 13. Kress, Robert W. "Variable Sweep Wing Design." AIAA 83

Decidual tissue growth and regression in the guinea pig: regulation by uterine blood flow and relation to circulating progesterone concentrations.

PubMed

Garris, D R

1984-05-01

The role of uterine blood flow (UBF) in the modulation of experimentally induced decidua formation was assessed in mature guinea pigs. The response to endometrial trauma, as indexed by uterine weight changes, was dependent upon the type of stimulus used, with deciduogenic effectiveness as follows: saline = oil = knife scratch less than scissor cut. Both the knife scratch and scissor cut techniques induced elevations in UBF compared with control values. Neither uterine weight nor UBF increased when trauma was applied to unresponsive uteri, indicating that inflammation was not the cause of uterine hyperemia. Uterine weight increased from basal levels on the day of trauma (i.e. day 5 of the estrous cycle) to a maximal weight between days 10 and 12 posttrauma. Maximal growth of the induced decidua occurred under conditions of elevated UBF. Subsequently, UBF declined between days 10 and 15 posttrauma, preceding the associate resorption of the induced decidua. During the period of decidua growth, serum progesterone levels were elevated compared with those in control animals. These data indicate that experimentally induced decidua formation in the guinea pig is associated with uterine hyperemia and increased corpus luteum activity, both of which are necessary for proper endometrial differentiation. It is hypothesized that these events mimic the uterine hyperemia associated with blastocyst implanplantation and early placentation in this species.

A refined surgical treatment modality for bromhidrosis: Subcutaneous scissor with micropore.

PubMed

Dai, Yeqin; Xu, Ai-E; He, Junhua

2017-05-01

Axillary bromhidrosis has a strong negative effect on one's social life. A high success rate and few complications are criteria for a surgical treatment. The objective of this study was to evaluate a new surgical treatment modality for bromhidrosis: subcutaneous scissor with micropore. Twenty patients with bromhidrosis were treated. Patients were placed in a supine position with their treated arms abducted to 110°. After injection of 60 mL of tumescent solution into each axilla, one small incision was made at the middle axillary of the hair-bearing area. The whole hair-bearing skin was undermined at the level of the superficial fat to obtain adequate skin eversion. The flaps were everted to offer full exposure of the apocrine glands, and meticulous excision of each gland was performed. Both sides were punctured with scalpel. The micropore was used for drainage, and whose width was just 3 mm. Finally, the incisions were re-approximated, and bulky compressive dressings were applied to the area for 72 hours. Of the 40 axillae (20 patients), 34 (85.0%) showed excellent results, and six (15.0%) had good results. Malodor was significantly decreased. There were no serious complications. This technique can produce excellent results with a lower complication rate than most other surgical modalities and can be performed without costly equipment. © 2017 Wiley Periodicals, Inc.

Accelerated fatigue durability of a high performance composite

NASA Technical Reports Server (NTRS)

Rotem, A.

1982-01-01

The fatigue behavior of multidirectional graphite-epoxy laminates was analyzed theoretically and experimentally in an effort to establish an accelerated testing methodology. Analysis of the failure mechanism in fatigue of the laminates led to the determination of the failure mode governing fracture. The nonlinear, cyclic-dependent shear modulus was used to calculate the changing stress field in the laminate during the fatigue loading. Fatigue tests were performed at three different temperatures: 25 C, 74 C, and 114 C. The prediction of the S-N curves was made based on the artificial static strength artificial static strength at a reference temperature and the fatigue functions associated with them. The prediction of an S-N curve at other temperatures was performed using shifting factors determined for the specific failure mode. For multidirectional laminates, different S-N curves at different temperatures could be predicted using these shifting factors. Different S-N curves at different temperatures occur only when the fatigue failure mode is matrix dominated. It was found that whenever the fatigue failure mode is fiber dominated, temperature, over the range investigated, had no influence on the fatigue life. These results permit the prediction of long-time, low temperature fatigue behavior from data obtained in short time, high temperature testing, for laminates governed by a matrix failure mode.

In Tropical Lowland Rain Forests Monocots have Tougher Leaves than Dicots, and Include a New Kind of Tough Leaf

PubMed Central

Dominy, Nathaniel J.; Grubb, Peter J.; Jackson, Robyn V.; Lucas, Peter W.; Metcalfe, Daniel J.; Svenning, Jens-Christian; Turner, Ian M.

2008-01-01

Background and Aims There has been little previous work on the toughness of the laminae of monocots in tropical lowland rain forest (TLRF) despite the potential importance of greater toughness in inhibiting herbivory by invertebrates. Of 15 monocot families with >100 species in TLRF, eight have notably high densities of fibres in the lamina so that high values for toughness are expected. Methods In north-eastern Australia punch strength was determined with a penetrometer for both immature leaves (approx. 30 % final area on average) and fully expanded, fully toughened leaves. In Singapore and Panama, fracture toughness was determined with an automated scissors apparatus using fully toughened leaves only. Key Results In Australia punch strength was, on average, 7× greater in shade-tolerant monocots than in neighbouring dicots at the immature stage, and 3× greater at the mature stage. In Singapore, shade-tolerant monocots had, on average, 1·3× higher values for fracture toughness than neighbouring dicots. In Panama, both shade-tolerant and gap-demanding monocots were tested; they did not differ in fracture toughness. The monocots had markedly higher values than the dicots whether shade-tolerant or gap-demanding species were considered. Conclusions It is predicted that monocots will be found to experience lower rates of herbivory by invertebrates than dicots. The tough monocot leaves include both stiff leaves containing relatively little water at saturation (e.g. palms), and leaves which lack stiffness, are rich in water at saturation and roll readily during dry weather or even in bright sun around midday (e.g. gingers, heliconias and marants). Monocot leaves also show that it is possible for leaves to be notably tough throughout the expansion phase of development, something never recorded for dicots. The need to broaden the botanist's mental picture of a ‘tough leaf’ is emphasized. PMID:18387969

In tropical lowland rain forests monocots have tougher leaves than dicots, and include a new kind of tough leaf.

PubMed

Dominy, Nathaniel J; Grubb, Peter J; Jackson, Robyn V; Lucas, Peter W; Metcalfe, Daniel J; Svenning, Jens-Christian; Turner, Ian M

2008-06-01

There has been little previous work on the toughness of the laminae of monocots in tropical lowland rain forest (TLRF) despite the potential importance of greater toughness in inhibiting herbivory by invertebrates. Of 15 monocot families with >100 species in TLRF, eight have notably high densities of fibres in the lamina so that high values for toughness are expected. In north-eastern Australia punch strength was determined with a penetrometer for both immature leaves (approx. 30 % final area on average) and fully expanded, fully toughened leaves. In Singapore and Panama, fracture toughness was determined with an automated scissors apparatus using fully toughened leaves only. In Australia punch strength was, on average, 7x greater in shade-tolerant monocots than in neighbouring dicots at the immature stage, and 3x greater at the mature stage. In Singapore, shade-tolerant monocots had, on average, 1.3x higher values for fracture toughness than neighbouring dicots. In Panama, both shade-tolerant and gap-demanding monocots were tested; they did not differ in fracture toughness. The monocots had markedly higher values than the dicots whether shade-tolerant or gap-demanding species were considered. It is predicted that monocots will be found to experience lower rates of herbivory by invertebrates than dicots. The tough monocot leaves include both stiff leaves containing relatively little water at saturation (e.g. palms), and leaves which lack stiffness, are rich in water at saturation and roll readily during dry weather or even in bright sun around midday (e.g. gingers, heliconias and marants). Monocot leaves also show that it is possible for leaves to be notably tough throughout the expansion phase of development, something never recorded for dicots. The need to broaden the botanist's mental picture of a 'tough leaf' is emphasized.

Resonator modes and mode dynamics for an external cavity-coupled laser array

NASA Astrophysics Data System (ADS)

Nair, Niketh; Bochove, Erik J.; Aceves, Alejandro B.; Zunoubi, Mohammad R.; Braiman, Yehuda

2015-03-01

Employing a Fox-Li approach, we derived the cold-cavity mode structure and a coupled mode theory for a phased array of N single-transverse-mode active waveguides with feedback from an external cavity. We applied the analysis to a system with arbitrary laser lengths, external cavity design and coupling strengths to the external cavity. The entire system was treated as a single resonator. The effect of the external cavity was modeled by a set of boundary conditions expressed by an N-by-N frequency-dependent matrix relation between incident and reflected fields at the interface with the external cavity. The coupled mode theory can be adapted to various types of gain media and internal and external cavity designs.

Emergence of resonant mode-locking via delayed feedback in quantum dot semiconductor lasers.

PubMed

Tykalewicz, B; Goulding, D; Hegarty, S P; Huyet, G; Erneux, T; Kelleher, B; Viktorov, E A

2016-02-22

With conventional semiconductor lasers undergoing external optical feedback, a chaotic output is typically observed even for moderate levels of the feedback strength. In this paper we examine single mode quantum dot lasers under strong optical feedback conditions and show that an entirely new dynamical regime is found consisting of spontaneous mode-locking via a resonance between the relaxation oscillation frequency and the external cavity repetition rate. Experimental observations are supported by detailed numerical simulations of rate equations appropriate for this laser type. The phenomenon constitutes an entirely new mode-locking mechanism in semiconductor lasers.

Microstructure Evolution and Mechanical Behavior of 2219 Aluminum Alloys Additively Fabricated by the Cold Metal Transfer Process

PubMed Central

Fang, Xuewei; Li, Hui; Li, Chaolong; Lu, Bingheng

2018-01-01

In this research, four different welding arc modes including conventional cold metal transfer (CMT), CMT-Pulse (CMT-P), CMT-Advanced (CMT-ADV), and CMT pulse advanced (CMT-PADV) were used to deposit 2219-Al wire. The effects of different arc modes on porosity, pore size distribution, microstructure evolution, and mechanical properties were thoroughly investigated. The statistical analysis of the porosity and its size distribution indicated that the CMT-PADV process gave the smallest pore area percentage and pore aspect ratio, and had almost no larger pores. The results from optical microscopy, scanning electron microscopy, and fractographic morphology proved that uniform and fine equiaxed grains, evenly distributed Al2Cu second phase particles were formed during the CMT-PADV process. Furthermore, the X-ray diffraction test ascertained that the CMT-PADV sample had the smallest lattice parameter and the highest solute Cu content. Besides, the tensile strength could reach 283 MPa, the data scattering was the smallest, and the strength scattering of the sample in the horizontal direction was the shortest. In addition, the strength properties were nearly isotropic, with only 5 MPa difference in the vertical and horizontal directions. The above mentioned results indicated that the mechanical properties of 2219 aluminum alloy was improved using the CMT-PADV arc mode. PMID:29772708

Effect of Gamma Ray Irradiation on Interlaminar Shear Strength of Glass Fiber Reinforced Plastics at 77 K

NASA Astrophysics Data System (ADS)

Nishimura, A.; Nishijima, S.; Izumi, Y.

2008-03-01

It is known that an organic material is damaged by gamma ray irradiation, and the strength after irradiation has dependence on the gamma ray dose. These issues are important not only to make global understanding of electric insulating performance of glass fiber reinforced plastics (GFRP) under irradiation condition but also to develop new insulation materials. This paper presents the dependence of fracture mode and interlaminar shear strength (ILSS) on the material and the gamma ray irradiation effect on the fracture mode and the ILSS. 6 mm radius loading nose and supports were used to prompt ILS fracture for a short beam test. A 2.5 mm thick small specimen machined out of a 13 mm thick G-10CR GFRP plate (sliced specimen) showed lower ILSS and translaminar shear (TLS) fracture, although the same size specimen prepared from a 2.5 mm G-10CR GFRP plate (non-sliced specimen) showed ILS fracture and the higher ILSS. Both type of specimens showed the degradation of ILSS after gamma ray irradiation. The fracture mode of the non-sliced specimen changed from ILS to TLS fracture and no bending fracture was observed. The resistance to shear deformation of glass cloth/epoxy laminate structure would be damaged by the irradiation.

Inverse cascades and resonant triads in rotating and stratified turbulence

NASA Astrophysics Data System (ADS)

Oks, D.; Mininni, P. D.; Marino, R.; Pouquet, A.

2017-11-01

Kraichnan's seminal ideas on inverse cascades yielded new tools to study common phenomena in geophysical turbulent flows. In the atmosphere and the oceans, rotation and stratification result in a flow that can be approximated as two-dimensional at very large scales but which requires considering three-dimensional effects to fully describe turbulent transport processes and non-linear phenomena. Motions can thus be classified into two classes: fast modes consisting of inertia-gravity waves and slow quasi-geostrophic modes for which the Coriolis force and horizontal pressure gradients are close to balance. In this paper, we review previous results on the strength of the inverse cascade in rotating and stratified flows and then present new results on the effect of varying the strength of rotation and stratification (measured by the inverse Prandtl ratio N/f, of the Coriolis frequency to the Brunt-Väisäla frequency) on the amplitude of the waves and on the flow quasi-geostrophic behavior. We show that the inverse cascade is more efficient in the range of N/f for which resonant triads do not exist, 1 /2 ≤N /f ≤2 . We then use the spatio-temporal spectrum to show that in this range slow modes dominate the dynamics, while the strength of the waves (and their relevance in the flow dynamics) is weaker.

Microstructure Evolution and Mechanical Behavior of 2219 Aluminum Alloys Additively Fabricated by the Cold Metal Transfer Process.

PubMed

Fang, Xuewei; Zhang, Lijuan; Li, Hui; Li, Chaolong; Huang, Ke; Lu, Bingheng

2018-05-16

In this research, four different welding arc modes including conventional cold metal transfer (CMT), CMT-Pulse (CMT-P), CMT-Advanced (CMT-ADV), and CMT pulse advanced (CMT-PADV) were used to deposit 2219-Al wire. The effects of different arc modes on porosity, pore size distribution, microstructure evolution, and mechanical properties were thoroughly investigated. The statistical analysis of the porosity and its size distribution indicated that the CMT-PADV process gave the smallest pore area percentage and pore aspect ratio, and had almost no larger pores. The results from optical microscopy, scanning electron microscopy, and fractographic morphology proved that uniform and fine equiaxed grains, evenly distributed Al₂Cu second phase particles were formed during the CMT-PADV process. Furthermore, the X-ray diffraction test ascertained that the CMT-PADV sample had the smallest lattice parameter and the highest solute Cu content. Besides, the tensile strength could reach 283 MPa, the data scattering was the smallest, and the strength scattering of the sample in the horizontal direction was the shortest. In addition, the strength properties were nearly isotropic, with only 5 MPa difference in the vertical and horizontal directions. The above mentioned results indicated that the mechanical properties of 2219 aluminum alloy was improved using the CMT-PADV arc mode.

Neuromuscular and muscle-tendon system adaptations to isotonic and isokinetic eccentric exercise.

PubMed

Guilhem, G; Cornu, C; Guével, A

2010-06-01

To present the properties of an eccentric contraction and compare neuromuscular and muscle-tendon system adaptations induced by isotonic and isokinetic eccentric trainings. An eccentric muscle contraction is characterized by the production of muscle force associated to a lengthening of the muscle-tendon system. This muscle solicitation can cause micro lesions followed by a regeneration process of the muscle-tendon system. Eccentric exercise is commonly used in functional rehabilitation for its positive effect on collagen synthesis but also for resistance training to increase muscle strength and muscle mass in athletes. Indeed, eccentric training stimulates muscle hypertrophy, increases the fascicle pennation angle, fascicles length and neural activation, thus inducing greater strength gains than concentric or isometric training programs. Eccentric exercise is commonly performed either against a constant external load (isotonic) or at constant velocity (isokinetic), inducing different mechanical constraints. These different mechanical constraints could induce structural and neural adaptive strategies specific to each type of exercise. The literature tends to show that isotonic mode leads to a greater strength gain than isokinetic mode. This observation could be explained by a greater neuromuscular activation after IT training. However, the specific muscle adaptations induced by each mode remain difficult to determine due to the lack of standardized, comparative studies. 2010 Elsevier Masson SAS. All rights reserved.

Linear and circular dichroism characterization of thionine binding mode with DNA polynucleotides

NASA Astrophysics Data System (ADS)

Tuite, Eimer Mary; Nordén, Bengt

2018-01-01

The binding mode of thionine (3,7-diamino-5-phenothiazinium) with alternating and non-alternating DNA polynucleotides at low binding ratios was conclusively determined using linear and circular dichroism spectroscopies. The binding to [poly(dG-dC)]2 and poly(dG)·poly(dC) was purely intercalative and was insensitive to ionic strength. Intercalative binding to [poly(dA-dT)]2 is observed at low ionic strength, but a shift of some dye to an non-intercalative mode is observed as the background salt concentration increases. With poly(dA)·poly(dT), intercalative binding is unfavourable, although some dye molecules may intercalate at low ionic strength, and groove binding is strongly promoted with increasing concentration of background salt. However, stacking with bases is observed with single-stranded poly(dA) and with triplex poly(dT)*poly(dA)·poly(dT) which suggests that the unusual structure of poly(dA)·poly(dT) precludes intercalation. Thionine behaves similarly to the related dye methylene blue, and small differences may be attributed either to the ability of thionine to form H-bonds that stabilize intercalation or to its improved stacking interactions in the basepair pocket on steric grounds.

Notch strengthening or weakening governed by transition of shear failure to normal mode fracture

PubMed Central

Lei, Xianqi; Li, Congling; Shi, Xinghua; Xu, Xianghong; Wei, Yujie

2015-01-01

It is generally observed that the existence of geometrical discontinuity like notches in materials will lead to strength weakening, as a resultant of local stress concentration. By comparing the influence of notches to the strength of three typical materials, aluminum alloys with intermediate tensile ductility, metallic glasses with no tensile ductility, and brittle ceramics, we observed strengthening in aluminum alloys and metallic glasses: Tensile strength of the net section in circumferentially notched cylinders increases with the constraint quantified by the ratio of notch depth over notch root radius; in contrast, the ceramic exhibit notch weakening. The strengthening in the former two is due to resultant deformation transition: Shear failure occurs in intact samples while samples with deep notches break in normal mode fracture. No such deformation transition was observed in the ceramic, and stress concentration leads to its notch weakening. The experimental results are confirmed by theoretical analyses and numerical simulation. The results reported here suggest that the conventional criterion to use brittleness and/or ductility to differentiate notch strengthening or weakening is not physically sound. Notch strengthening or weakening relies on the existence of failure mode transition and materials exhibiting shear failure while subjected to tension will notch strengthen. PMID:26022892

Effects of drying agents on bond strength of etch-and-rinse adhesive systems to enamel immediately after bleaching.

PubMed

Niat, Alireza Boruzi; Yazdi, Fatmeh Maleknejad; Koohestanian, Niloufar

2012-12-01

To determine the effect of drying agents and adhesive solvents on the bond strength of resin composite to enamel immediately after bleaching. Sixty healthy human premolars were bleached using 15% carbamide peroxide gel and randomly divided into three groups according to the immersing solutions applied immediately after bleaching: 70% alcohol, acetone, and distilled water. Each group was randomly divided into two subgroups according to the adhesives that were applied: an alcohol-based adhesive (Single Bond) and an acetone-based adhesive (One Step). By using rubber washers, composite Z100 was placed onto the enamel and shear bond strength was evaluated in a universal testing machine at a crosshead speed of 1 mm/min. The type of failure was also assessed using a stereomicroscope. The data were statistically analyzed by two-way ANOVA and Tukey's post-hoc test (α = 0.05). Fisher's Exact test was used to evaluate differences in the failure modes. Statistical analysis showed that the bond strength of the distilled water groups was significantly lower than that of the other groups, but the bond strengths of the two groups where a drying agent was applied were similar to that of the unbleached group. The acetone-based adhesive (One Step) provided higher bond strength than did the alcohol-based adhesive (Single Bond) (p < 0.05). There was no interaction between the two variables (p > 0.05). Fisher's Exact test showed there was no significant difference in the failure mode of all the experimental groups (p > 0.05). The application of drying agents improves the bond strength of resin composite to bleached enamel. Furthermore, the acetone-based adhesive used in the study had a higher bond strength to bleached enamel than did the alcohol-based adhesive used.

Laboratory Determination of the Infrared Band Strengths of Pyrene Frozen in Water Ice: Implications for the Composition of Interstellar Ices

NASA Technical Reports Server (NTRS)

Hardegree-Ullman, E.E.; Gudipati, M.S.; Boogert, A.C.A.; Lignell, H.; Allamandola, L.J.; Stapelfeldt, K. R.; Werner, M.

2014-01-01

Broad infrared emission features (e.g., at 3.3, 6.2, 7.7, 8.6, and 11.3 micrometers) from the gas phase interstellar medium have long been attributed to polycyclic aromatic hydrocarbons (PAHs). A significant portion (10 to 20%) of the Milky Way's carbon reservoir is locked in PAH molecules, which makes their characterization integral to our understanding of astrochemistry. In molecular clouds and the dense envelopes and disks of young stellar objects (YSOs), PAHs are expected to be frozen in the icy mantles of dust grains where they should reveal themselves through infrared absorption. To facilitate the search for frozen interstellar PAHs, laboratory experiments were conducted to determine the positions and strengths of the bands of pyrene mixed with H2O and deuterium oxide ices. The deuterium oxide mixtures are used to measure pyrene bands that are masked by the strong bands of H2O, leading to the first laboratory determination of the band strength for the CH stretching mode of pyrene in water ice near 3.25 micrometers. Our infrared band strengths were normalized to experimentally determined ultraviolet (UV) band strengths, and we find that they are generally approximately 50% larger than those reported by Bouwman et al. (2011) based on theoretical strengths. These improved band strengths were used to reexamine YSO spectra published by Boogert et al. (2008) to estimate the contribution of frozen PAHs to absorption in the 5 to 8 micrometer spectral region, taking into account the strength of the 3.25 micrometer CH stretching mode. It is found that frozen neutral PAHs contain 5 to 9% of the cosmic carbon budget, and account for 2 to 9% of the unidentified absorption in the 5 to 8 micrometer region.

Microstructure-failure mode correlations in braided composites

NASA Technical Reports Server (NTRS)

Filatovs, G. J.; Sadler, Robert L.; El-Shiekh, Aly

1992-01-01

Explication of the fracture processes of braided composites is needed for modeling their behavior. Described is a systematic exploration of the relationship between microstructure, loading mode, and micro-failure mechanisms in carbon/epoxy braided composites. The study involved compression and fracture toughness tests and optical and scanning electron fractography, including dynamic in-situ testing. Principal failure mechanisms of low sliding, buckling, and unstable crack growth are correlated to microstructural parameters and loading modes; these are used for defining those microstructural conditions which are strength limiting.

Profile of isokinetic eccentric-to-concentric strength ratios of shoulder rotator muscles in elite female team handball players.

PubMed

Andrade, Marilia Dos Santos; Fleury, Anna Maria; de Lira, Claudio Andre Barbosia; Dubas, Joao Paulo; da Silva, Antonio Carlos

2010-05-01

The purpose of this study was to establish the isokinetic profile of shoulder rotator muscles strength in female handball players. Twenty-seven handball players performed concentric and eccentric strength tests of both dominant and non-dominant upper limbs on an isokinetic dynamometer. Internal and external rotator muscles peak torque was assessed at 1.05, 3.14, and 5.23 rad . s(-1) in concentric mode and at 3.14 and 5.23 rad . s(-1) in eccentric mode. Concentric balance ratio and functional ratio were obtained. Bi-lateral deficiency was compared. Concentric strength for internal and external rotation was significantly greater for the dominant than for the non-dominant limb for all speeds (P < or = 0.0001). For eccentric actions, internal rotator muscles were stronger in the dominant than the non-dominant limb (P < or = 0.0001) at both speeds. Concentric balance and functional balance ratios did not differ between sides at 3.14 rad . s(-1) (P = 0.1631), but at 5.23 rad . s(-1) the functional balance ratio in the dominant limb was lower than for the non-dominant limb (P = 0.0500). Although the dominant side was stronger than the non-dominant side, balance concentric ratios remained the same, with only the functional strength ratio different at 5.23 rad . s(-1). Our results suggest that concentric strength exercises be used for internal and external rotators on the non-dominant side, and functional exercise that improves eccentric rotation strength for prevention programmes.

Large-Scale Brain Network Coupling Predicts Acute Nicotine Abstinence Effects on Craving and Cognitive Function

PubMed Central

Lerman, Caryn; Gu, Hong; Loughead, James; Ruparel, Kosha; Yang, Yihong; Stein, Elliot A.

2014-01-01

IMPORTANCE Interactions of large-scale brain networks may underlie cognitive dysfunctions in psychiatric and addictive disorders. OBJECTIVES To test the hypothesis that the strength of coupling among 3 large-scale brain networks–salience, executive control, and default mode–will reflect the state of nicotine withdrawal (vs smoking satiety) and will predict abstinence-induced craving and cognitive deficits and to develop a resource allocation index (RAI) that reflects the combined strength of interactions among the 3 large-scale networks. DESIGN, SETTING, AND PARTICIPANTS A within-subject functional magnetic resonance imaging study in an academic medical center compared resting-state functional connectivity coherence strength after 24 hours of abstinence and after smoking satiety. We examined the relationship of abstinence-induced changes in the RAI with alterations in subjective, behavioral, and neural functions. We included 37 healthy smoking volunteers, aged 19 to 61 years, for analyses. INTERVENTIONS Twenty-four hours of abstinence vs smoking satiety. MAIN OUTCOMES AND MEASURES Inter-network connectivity strength (primary) and the relationship with subjective, behavioral, and neural measures of nicotine withdrawal during abstinence vs smoking satiety states (secondary). RESULTS The RAI was significantly lower in the abstinent compared with the smoking satiety states (left RAI, P = .002; right RAI, P = .04), suggesting weaker inhibition between the default mode and salience networks. Weaker inter-network connectivity (reduced RAI) predicted abstinence-induced cravings to smoke (r = −0.59; P = .007) and less suppression of default mode activity during performance of a subsequent working memory task (ventromedial prefrontal cortex, r = −0.66, P = .003; posterior cingulate cortex, r = −0.65, P = .001). CONCLUSIONS AND RELEVANCE Alterations in coupling of the salience and default mode networks and the inability to disengage from the default mode network may be critical in cognitive/affective alterations that underlie nicotine dependence. PMID:24622915

Acute Effects of Static vs. Ballistic Stretching on Strength and Muscular Fatigue Between Ballet Dancers and Resistance-Trained Women.

PubMed

Lima, Camila D; Brown, Lee E; Wong, Megan A; Leyva, Whitney D; Pinto, Ronei S; Cadore, Eduardo L; Ruas, Cassio V

2016-11-01

Lima, CD, Brown, LE, Wong, MA, Leyva, WD, Pinto, RS, Cadore, EL, and Ruas, CV. Acute effects of static vs. ballistic stretching on strength and muscular fatigue between ballet dancers and resistance-trained women. J Strength Cond Res 30(11): 3220-3227, 2016-Stretching is used to increase joint range of motion, but the acute effects can decrease muscle strength. However, this may depend on the population or mode of stretching. The purpose of this study was to compare the acute effects of static vs. ballistic stretching on strength and muscular fatigue between ballet dancers and resistance-trained women. Fifteen resistance-trained women (age 23.8 ± 1.80 years, mass 67.47 ± 7.77 kg, height 168.30 ± 5.53 cm) and 12 ballet dancers (age 22.8 ± 3.04 years, mass 58.67 ± 5.65 kg, height 168.00 ± 7.69 cm) performed 5 days of testing. The first day was control (no stretching), whereas the other 4 days were static or ballistic stretching in a counterbalanced order. Range of motion, strength, and fatigue tests were also performed. Both groups demonstrated a significant decrease in hamstrings strength after static (102.71 ± 2.67 N·m) and ballistic stretching (99.49 ± 2.61 N·m) compared with control (113.059 ± 3.25 N·m), with no changes in quadriceps strength. For fatigue, only ballet dancers demonstrated a decrease from control (71.79 ± 4.88%) to ballistic (65.65 ± 8.19%), but no difference with static (65.01 ± 12.29%). These findings suggest that stretching decreases hamstrings strength similarly in ballet dancers and resistance-trained women, with no differences between modes of stretching. However, ballistic stretching only decreased muscular fatigue in ballet dancers, but not in resistance-trained women. Therefore, no stretching should be performed before strength performance. However, ballistic stretching may decrease acute muscular fatigue in ballet dancers.

Evaluation of shear bond strength of porcelain bonded to laser welded titanium surface and determination of mode of bond failure.

PubMed

Patil, Narendra P; Dandekar, Minal; Nadiger, Ramesh K; Guttal, Satyabodh S

2010-09-01

The aim of this study was to evaluate the shear bond strength of porcelain to laser welded titanium surface and to determine the mode of bond failure through scanning electron microscopy (SEM) and energy dispersive spectrophotometry (EDS). Forty five cast rectangular titanium specimens with the dimension of 10 mm x 8 mm x 1 mm were tested. Thirty specimens had a perforation of 2 mm diameter in the centre. These were randomly divided into Group A and B. The perforations in the Group B specimens were repaired by laser welding using Cp Grade II titanium wire. The remaining 15 specimens were taken as control group. All the test specimens were layered with low fusing porcelain and tested for shear bond strength. The debonded specimens were subjected to SEM and EDS. Data were analysed with 1-way analysis of variance and Student's t-test for comparison among the different groups. One-way analysis of variance (ANOVA) showed no statistically significant difference in shear bond strength values at a 5% level of confidence. The mean shear bond strength values for control group, Group A and B was 8.4 +/- 0.5 Mpa, 8.1 +/- 0.4 Mpa and 8.3 +/- 0.3 Mpa respectively. SEM/EDS analysis of the specimens showed mixed and cohesive type of bond failure. Within the limitations of the study laser welding did not have any effect on the shear bond strength of porcelain bonded to titanium.

Effect of Tool Offset and Tool Rotational Speed on Enhancing Mechanical Property of Al/Mg Dissimilar FSW Joints

NASA Astrophysics Data System (ADS)

Liang, Zhiyuan; Chen, Ke; Wang, Xiaona; Yao, Junshan; Yang, Qi; Zhang, Lanting; Shan, Aidang

2013-08-01

Friction stir welding (FSW) is a promising solid-state joining technique for producing effective welds between Al alloy and Mg alloy. However, previously reported Al/Mg dissimilar FSW joints generally have limited strength or barely any ductility with relatively high strength, which was blamed on the brittle intermetallics formed during welding. In this study, effective joints with comparably high strength (163 MPa) and large elongation (~6 pct) were obtained. Three crucial/weak zones were identified in the welds: (1) Al/Mg bottom interface (BI) zone that resulted from the insufficient materials' intermixing and interdiffusion; (2) banded structure (BS) zone which contains intermetallic particles possibly formed by constitutional liquation; and (3) softened Al alloy to the retreating side (SAA-RS) zone due to the dissolution and coarsening of the strengthening precipitates. Three fracture modes observed in the tensile specimens perpendicular to the weld seam were found closely related to these zones. Their microstructure evolution with the change of tool rotational speed and tool offset was characterized and the consequent effect on the fracture mode alteration was studied. It turned out that enhancing the strengths of all these zones, but keeping the strength of the SAA lowest, is an effective way for enhancing ductility while keeping comparatively high strength in Al/Mg FSW joints. Also, suggestions for further improving the mechanical property of the Al/Mg dissimilar FSW joints were made accordingly for practical applications.

Effects of silicon coating on bond strength of two different titanium ceramic to titanium.

PubMed

Ozcan, Isil; Uysal, Hakan

2005-08-01

This study investigated the effect of silicon coating (SiO2) by magnetron sputtering on bond strength of two different titanium ceramics to titanium. Sixty cast titanium specimens were prepared following the protocol ISO 9693. Titanium specimens were divided into two test and control groups with 15 specimens in each. Test groups were silicon coated by the magnetron sputtering technique. Two titanium ceramics (Triceram and Duceratin) were applied on both test (coated) and control (uncoated) metal specimens. The titanium-ceramic specimens were subjected to a three point flexural test. The groups were compared for their bond strength. SEM and SEM/EDS analyses were performed on the delaminated titanium surfaces to ascertain bond failure. The mean bond strength of Ti-Duceratin, Ti-Triceram, Si-coated Ti-Duceratin and Si-coated Ti-Triceram were 17.22+/-2.43, 23.31+/-3.18, 23.21+/-3.81 and 24.91+/-3.70 MPa, respectively. While the improvement in bond strength was 30% for Duceratin, it was statistically insignificant for Triceram. An adhesive mode of failure was observed in the Duceratin control group. In the silicoated Duceratin specimen, the bonded ceramic boundaries were wider but less than in the silicoated Triceram specimen. In the coated Triceram specimen, the ceramic retained areas were frequent and the failure mode was generally cohesive. Silicon coating was significantly effective in both preventing titanium oxide layer formation and in improving bond strength for Duceratin. However, it was of less value for Triceram.

Processing, Structural Characterization and Comparative Studies on Uniaxial Tensile Properties of a New Type of Porous Twisted Wire Material

PubMed Central

Wu, Fei; Zhou, Zhaoyao; Duan, Liuyang; Xiao, Zhiyu

2015-01-01

A self-developed rotary multi-cutter device cuts stainless steel wire ropes into segments to fabricate twisted wires. Stainless steel porous twisted wire materials (PTWMs) with a spatial composite intertexture structure are produced by the compaction and subsequent vacuum solid-phase sintering of twisted wires. The stainless steel PTWMs show two types of typical uniaxial tensile failure modes, i.e., a 45° angle fracture mode and an auxetic failure mode (the PTWMs expand along the direction perpendicular to the tension). The effects of the sintering parameters, porosities, wire diameters, and sampling direction on the tensile properties of the PTWMs are carefully investigated. By increasing the sintering temperature from 1130 °C to 1330 °C, the tensile strength of the PTWMs with 70% target porosity increased from 7.7 MPa to 28.6 MPa and the total failure goes down to 50%. When increasing the sintering time from 90 min to 150 min, the tensile strength increases from 12.4 MPa to 19.1 MPa and the total failure elongation drops to 78.6%. The tensile strength of the PTWMs increases from 28.9 MPa to 112.7 MPa with decreasing porosity from 69.5% to 46.0%, and the total failure elongation also increases from 14.8% to 40.7%. The tensile strength and the failure strain of the PTWMs with fine wires are higher than those of the PTWMs with coarse wires under the same porosity. Sampling direction has a small influence on the tensile properties of the PTWMs. PMID:28793526

An Experimental Investigation of Silicone-to-Metal Bond Strength in Composite Space Docking System Seals

NASA Technical Reports Server (NTRS)

Gaier, James R.; Siamidis, John; Larkin, Elizabeth M. G.

2010-01-01

The National Aeronautics and Space Administration (NASA) is currently developing a new universal docking mechanism for future space exploration missions called the Low Impact Docking System (LIDS). A candidate LIDS main interface seal design is a composite assembly of silicone elastomer seals vacuum molded into grooves in an electroless nickel plated aluminum retainer. The strength of the silicone-tometal bond is a critical consideration for the new system, especially due to the presence of small areas of disbond created during the molding process. In the work presented herein, seal-to-retainer bonds of subscale seal specimens with different sizes of intentional disbond were destructively tensile tested. Nominal specimens without intentional disbonds were also tested. Tension was applied either uniformly on the entire seal circumference or locally in one short circumferential length. Bond failure due to uniform tension produced a wide scatter of observable failure modes and measured load-displacement behaviors. Although the preferable failure mode for the seal-to-retainer bond is cohesive failure of the elastomer material, the dominant observed failure mode under the uniform loading condition was found to be the less desirable adhesive failure of the bond in question. The uniform tension case results did not show a correlation between disbond size and bond strength. Localized tension was found to produce failure either as immediate tearing of the elastomer material outside the bond region or as complete peel-out of the seal in one piece. The obtained results represent a valuable benchmark for comparison in the future between adhesion loads under various separation conditions and composite seal bond strength.

Processing, Structural Characterization and Comparative Studies on Uniaxial Tensile Properties of a New Type of Porous Twisted Wire Material.

PubMed

Wu, Fei; Zhou, Zhaoyao; Duan, Liuyang; Xiao, Zhiyu

2015-08-27

A self-developed rotary multi-cutter device cuts stainless steel wire ropes into segments to fabricate twisted wires. Stainless steel porous twisted wire materials (PTWMs) with a spatial composite intertexture structure are produced by the compaction and subsequent vacuum solid-phase sintering of twisted wires. The stainless steel PTWMs show two types of typical uniaxial tensile failure modes, i.e. , a 45° angle fracture mode and an auxetic failure mode (the PTWMs expand along the direction perpendicular to the tension). The effects of the sintering parameters, porosities, wire diameters, and sampling direction on the tensile properties of the PTWMs are carefully investigated. By increasing the sintering temperature from 1130 °C to 1330 °C, the tensile strength of the PTWMs with 70% target porosity increased from 7.7 MPa to 28.6 MPa and the total failure goes down to 50%. When increasing the sintering time from 90 min to 150 min, the tensile strength increases from 12.4 MPa to 19.1 MPa and the total failure elongation drops to 78.6%. The tensile strength of the PTWMs increases from 28.9 MPa to 112.7 MPa with decreasing porosity from 69.5% to 46.0%, and the total failure elongation also increases from 14.8% to 40.7%. The tensile strength and the failure strain of the PTWMs with fine wires are higher than those of the PTWMs with coarse wires under the same porosity. Sampling direction has a small influence on the tensile properties of the PTWMs.

The Impact of Thermocycling Process on the Dislodgement Force of Different Endodontic Cements

PubMed Central

Saghiri, Mohammad Ali; Asatourian, Armen; Garcia-Godoy, Franklin; Gutmann, James L.; Sheibani, Nader

2013-01-01

To evaluate the effects of thermocycling (500 cycles, 5°C/55°C) on the push-out bond strength of calcium silicate based cements including WMTA, Nano-WMTA, and Bioaggregate to root dentin. Forty-eight dentin slices were prepared and divided into 3 groups (n = 16) and filled with Angelus WMTA, Nano-WMTA, or Bioaggregate. After incubation, half of the samples were thermocycled while the other half remained untreated. Push-out bond strength was calculated, and the modes of the bond failures were determined by SEM. The highest bond strength was seen in nonthermocycled Nano-WMTA samples and the lowest in thermocycled Bioaggregate samples. The significant differences between nonthermocycled and thermocycled samples were only noticed in WMTA and Nano-WMTA groups (P < 0.001). The mode of failure for thermocycled samples of all three cements was mostly cohesive. Thermocycling process can drastically affect the push-out bond strength of calcium silicate based cements. The intrastructural damages occurred due to the thermal stresses, causing cohesive failures in set materials. Sealing property of endodontic cements which have experienced the thermal stresses can be jeopardized due to occlusal forces happening in furcation cites. PMID:24063004

Effects of stitching on fracture toughness of uniweave textile graphite/epoxy laminates

NASA Technical Reports Server (NTRS)

Sankar, Bhavani V.; Sharma, Suresh

1995-01-01

The effects of through-the-thickness stitching on impact damage resistance, impact damage tolerance, and Mode 1 and Mode 2 fracture toughness of textile graphite/epoxy laminates were studied experimentally. Graphite/epoxy laminates were fabricated from AS4 graphite uniweave textiles and 3501-6 epoxy using Resin Transfer Molding. The cloths were stitched with Kevlar(tm) and glass yarns before resin infusion. Delamination was implanted during processing to simulate impact damage. Sublaminate buckling tests were performed in a novel fixture to measure Compression After Impact (CAI) strength of stitched laminates. The results show that CAI strength can be improved up to 400% by through-the-thickness stitching. Double Cantilever Beam tests were performed to study the effect of stitching on Mode 1 fracture toughness G(sub 1c). It was found that G(sub 1c) increased 30 times for a low stitching density of 16 stitches/sq in. Mode 2 fracture toughness was measured by testing the stitched beams in End Notch Flexure tests. Unlike in the unstitiched beams, crack propagation in the stitched beams was steady. The current formulas for ENF tests were not found suitable for determining G(sub 2C) for stitched beams. Hence two new methods were developed - one based on crack area measured from ultrasonic C-scanning and the other based on equivalent crack area measured from the residual stiffness of the specimen. The G(sub 2c) was found to be at least 5-15 times higher for the stitched laminates. The mechanisms by which stitching increases the CAI strength and fracture toughness are discussed.

Isovector and isoscalar dipole excitations in 9Be and 10Be studied with antisymmetrized molecular dynamics

NASA Astrophysics Data System (ADS)

Kanada-En'yo, Yoshiko

2016-02-01

Isovector and isoscalar dipole excitations in 9Be and 10Be are investigated in the framework of antisymmetrized molecular dynamics, in which angular-momentum and parity projections are performed. In the present method, 1p-1h excitation modes built on the ground state and a large amplitude α -cluster mode are taken into account. The isovector giant dipole resonance (GDR) in E >20 MeV shows the two-peak structure, which is understood from the dipole excitation in the 2 α core part with the prolate deformation. Because of valence neutron modes against the 2 α core, low-energy E 1 resonances appear in E <20 MeV, exhausting about 20 % of the Thomas-Reiche-Kuhn sum rule and 10 % of the calculated energy-weighted sum. The dipole resonance at E ˜15 MeV in 10Be can be interpreted as the parity partner of the ground state having a 6He+α structure and has remarkable E 1 strength because of the coherent contribution of two valence neutrons. The isoscalar dipole strength for some low-energy resonances is significantly enhanced by the coupling with the α -cluster mode. For the E 1 strength of 9Be, the calculation overestimates the energy-weighted sum (EWS) in the low-energy (E <20 MeV) and GDR (20

Mode Selection Rules for a Two-Delay System with Positive and Negative Feedback Loops

NASA Astrophysics Data System (ADS)

Takahashi, Kin'ya; Kobayashi, Taizo

2018-04-01

The mode selection rules for a two-delay system, which has negative feedback with a short delay time t1 and positive feedback with a long delay time t2, are studied numerically and theoretically. We find two types of mode selection rules depending on the strength of the negative feedback. When the strength of the negative feedback |α1| (α1 < 0) is sufficiently small compared with that of the positive feedback α2 (> 0), 2m + 1-th harmonic oscillation is well sustained in a neighborhood of t1/t2 = even/odd, i.e., relevant condition. In a neighborhood of the irrelevant condition given by t1/t2 = odd/even or t1/t2 = odd/odd, higher harmonic oscillations are observed. However, if |α1| is slightly less than α2, a different mode selection rule works, where the condition t1/t2 = odd/even is relevant and the conditions t1/t2 = odd/odd and t1/t2 = even/odd are irrelevant. These mode selection rules are different from the mode selection rule of the normal two-delay system with two positive feedback loops, where t1/t2 = odd/odd is relevant and the others are irrelevant. The two types of mode selection rules are induced by individually different mechanisms controlling the Hopf bifurcation, i.e., the Hopf bifurcation controlled by the "boosted bifurcation process" and by the "anomalous bifurcation process", which occur for |α1| below and above the threshold value αth, respectively.

Performance evaluation of a second-generation elastic loop mobility system

NASA Technical Reports Server (NTRS)

Melzer, K. J.; Swanson, G. D.

1974-01-01

Tests were conducted to evaluate the mobility performance of a second-generation Elastic Loop Mobility System (ELMS II). Performance on level test lanes and slopes of lunar soil simulant (LSS) and obstacle-surmounting and crevasse-crossing capabilities were investigated. In addition, internal losses and contact pressure distributions were evaluated. To evaluate the soft-soil performance, two basic soil conditions were tested: loose (LSS1) and dense (LSS5). These conditions embrace the spectrum of soil strengths tested during recent studies for NASA related to the mobility performance of the LRV. Data indicated that for the tested range of the various performance parameters, performance was independent of unit load (contact pressure) and ELMS II drum angular velocity, but was influenced by soil strength and ELMS pitch mode. Power requirements were smaller at a given system output for dense soil than for loose soil. The total system output in terms of pull developed or slope-climbing capability was larger for the ELMS II operating in restrained-pitch mode than in free-pitch mode.

Mode Transitions in Magnetically Shielded Hall Effect Thrusters

NASA Technical Reports Server (NTRS)

Sekerak, Michael J.; Longmier, Benjamin W.; Gallimore, Alec D.; Huang, Wensheng; Kamhawi, Hani; Hofer, Richard R.; Jorns, Benjamin A.; Polk, James E.

2014-01-01

A mode transition study is conducted in magnetically shielded thrusters where the magnetic field magnitude is varied to induce mode transitions. Three different oscillatory modes are identified with the 20-kW NASA-300MS-2 and the 6-kW H6MS: Mode 1) global mode similar to unshielded thrusters at low magnetic fields, Mode 2) cathode oscillations at nominal magnetic fields, and Mode 3) combined spoke, cathode and breathing mode oscillations at high magnetic fields. Mode 1 exhibits large amplitude, low frequency (1-10 kHz), breathing mode type oscillations where discharge current mean value and oscillation amplitude peak. The mean discharge current is minimized while thrust-to-power and anode efficiency are maximized in Mode 2, where higher frequency (50-90 kHz), low amplitude, cathode oscillations dominate. Thrust is maximized in Mode 3 and decreases by 5-6% with decreasing magnetic field strength. The presence or absence of spokes and strong cathode oscillations do not affect each other or discharge current. Similar to unshielded thrusters, mode transitions and plasma oscillations affect magnetically shielded thruster performance and should be characterized during system development.

Binding mode and thermodynamic studies on the interaction of the anticancer drug dacarbazine and dacarbazine-Cu(II) complex with single and double stranded DNA.

PubMed

Temerk, Yassien; Ibrahim, Hossieny

2014-07-01

The binding mode and thermodynamic characteristics of the anticancer drug dacarbazine (Dac) with double and single stranded DNA were investigated in the absence and presence of Cu(II) using cyclic voltammetry, square wave voltammetry and fluorescence spectroscopy. The interaction of Dac and Dac-Cu(II) complex with dsDNA indicated their intercalation into the base stacking domain of dsDNA double helix and the strength of interaction is independent on the ionic strength. The interaction of Dac with dsDNA in the presence of Cu(II) leads to a much stronger intercalation. The interaction mode of Dac molecules with ssDNA is electrostatic attraction via negative phosphate on the exterior of the ssDNA with Dac. The binding constants, stoichiometric coefficients and thermodynamic parameters of Dac and Dac-Cu(II) complex with dsDNA and ssDNA were evaluated. Comparison of the mode interaction of Dac with dsDNA and ssDNA was discussed. The decrease of peak current of Dac was proportional to DNA concentration, which was applied for determination of dsDNA and ssDNA concentration. Copyright © 2014 Elsevier B.V. All rights reserved.

Modelling of Dynamic Rock Fracture Process with a Rate-Dependent Combined Continuum Damage-Embedded Discontinuity Model Incorporating Microstructure

NASA Astrophysics Data System (ADS)

Saksala, Timo

2016-10-01

This paper deals with numerical modelling of rock fracture under dynamic loading. For this end, a combined continuum damage-embedded discontinuity model is applied in finite element modelling of crack propagation in rock. In this model, the strong loading rate sensitivity of rock is captured by the rate-dependent continuum scalar damage model that controls the pre-peak nonlinear hardening part of rock behaviour. The post-peak exponential softening part of the rock behaviour is governed by the embedded displacement discontinuity model describing the mode I, mode II and mixed mode fracture of rock. Rock heterogeneity is incorporated in the present approach by random description of the rock mineral texture based on the Voronoi tessellation. The model performance is demonstrated in numerical examples where the uniaxial tension and compression tests on rock are simulated. Finally, the dynamic three-point bending test of a semicircular disc is simulated in order to show that the model correctly predicts the strain rate-dependent tensile strengths as well as the failure modes of rock in this test. Special emphasis is laid on modelling the loading rate sensitivity of tensile strength of Laurentian granite.

Bolted Joints in Three Axially Braided Carbon Fibre/Epoxy Textile Composites with Moulded-in and Drilled Fastener Holes

NASA Astrophysics Data System (ADS)

Ataş, Akın; Gautam, Mayank; Soutis, Constantinos; Potluri, Prasad

2017-04-01

Experimental behaviour of bolted joints in triaxial braided (0°/±45°) carbon fibre/epoxy composite laminates with drilled and moulded-in fastener holes has been investigated in this paper. Braided laminates were manufactured by vacuum infusion process using 12 K T700S carbon fibres (for bias and axial tows) and Araldite LY-564 epoxy resin. Moulded-in fastener holes were formed using guide pins which were inserted in the braided structure prior to the vacuum infusion process. The damage mechanism of the specimens was investigated using ultrasonic C-Scan technique. The specimens were dimensioned to obtain a bearing mode of failure. The bearing strength of the specimens with moulded-in hole was reduced in comparison to the specimens with drilled hole, due to the increased fibre misalignment angle following the pin insertion procedure. An improvement on the bearing strength of moulded-in hole specimens might be developed if the specimen dimensions would be prepared for a net-tension mode of failure where the fibre misalignment would not have an effect as significant as in the case of bearing failure mode, but this mode should be avoided since it leads to sudden catastrophic failures.

Effects of structure distortion on optical phonon properties of crystalline beta-BaTeMo{sub 2}O{sub 9}—A novel nonlinear optical material: Infrared and Raman spectra as well as first-principles calculations

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

Zhou, S. T.; Huang, Y.; Qiu, W. Y.

2013-12-21

The infrared dielectric property of monoclinic BaTeMo{sub 2}O{sub 9} single crystals is studied by polarized IR reflectance spectra from 20 to 1800 cm{sup −1}. Based on the modified Lorentz model, the frequencies, strengths, and dampings of TO modes as well as the orientations of the dipole momenta are determined, agreeing well with Raman spectra and results from First-principles calculation. The observed modes are visually assigned to the specific atoms' motions in the primitive cell based on the theory calculations. A large shift of the internal modes of the anion groups relative to free anion co-ordination polyhedra is observed, which can bemore » used to indicate the distortions of co-ordination polyhedra related to the nonlinear optical properties. Further, the experimental results of the strengths of the oscillators support the elimination and splitting of degenerate modes in free regular polyhedrons. These results offer a way to evaluate the nonlinear optical properties by use of traditional IR reflectivity spectra.« less

Dynamics of flows, fluctuations, and global instability under electrode biasing in a linear plasma device

NASA Astrophysics Data System (ADS)

Desjardins, T. R.; Gilmore, M.

2016-05-01

Grid biasing is utilized in a large-scale helicon plasma to modify an existing instability. It is shown both experimentally and with a linear stability analysis to be a hybrid drift-Kelvin-Helmholtz mode. At low magnetic field strengths, coherent fluctuations are present, while at high magnetic field strengths, the plasma is broad-band turbulent. Grid biasing is used to drive the once-coherent fluctuations to a broad-band turbulent state, as well as to suppress them. There is a corresponding change in the flow shear. When a high positive bias (10Te) is applied to the grid electrode, a large-scale ( n ˜/n ≈50 % ) is excited. This mode has been identified as the potential relaxation instability.

Faithful state transfer between two-level systems via an actively cooled finite-temperature cavity

NASA Astrophysics Data System (ADS)

Sárkány, Lőrinc; Fortágh, József; Petrosyan, David

2018-03-01

We consider state transfer between two qubits—effective two-level systems represented by Rydberg atoms—via a common mode of a microwave cavity at finite temperature. We find that when both qubits have the same coupling strength to the cavity field, at large enough detuning from the cavity mode frequency, quantum interference between the transition paths makes the swap of the excitation between the qubits largely insensitive to the number of thermal photons in the cavity. When, however, the coupling strengths are different, the photon-number-dependent differential Stark shift of the transition frequencies precludes efficient transfer. Nevertheless, using an auxiliary cooling system to continuously extract the cavity photons, we can still achieve a high-fidelity state transfer between the qubits.

Overdense microwave plasma heating in the CNT stellarator

NASA Astrophysics Data System (ADS)

Hammond, K. C.; Diaz-Pacheco, R. R.; Köhn, A.; Volpe, F. A.; Wei, Y.

2018-02-01

Overdense plasmas have been attained with 2.45 GHz microwave heating in the low-field, low-aspect-ratio CNT stellarator. Densities higher than four times the ordinary (O) mode cutoff density were measured with 8 kW of power injected in the O-mode and, alternatively, with 6.5 kW in the extraordinary (X) mode. The temperature profiles peak at the plasma edge. This was ascribed to collisional damping of the X-mode at the upper hybrid resonant layer. The X-mode reaches that location by tunneling, mode-conversions or after polarization-scrambling reflections off the wall and in-vessel coils, regardless of the initial launch being in O- or X-mode. This interpretation was confirmed by full-wave numerical simulations. Also, as the CNT plasma is not completely ionized at these low microwave power levels, electron density was shown to increase with power. A dependence on magnetic field strength was also observed, for O-mode launch.

Asymmetric linear efficiency and bunching mechanisms of TM modes for electron cyclotron maser

NASA Astrophysics Data System (ADS)

Chang, T. H.; Huang, W. C.; Yao, H. Y.; Hung, C. L.; Chen, W. C.; Su, B. Y.

2017-02-01

This study examines the transverse magnetic (TM) waveguide modes, which have long been considered as the unsuitable ones for the operation of the electron cyclotron maser. The beam-wave coupling strength of the TM modes, as expected, is found to be relatively weak as compared with that of the transverse electric (TE) waveguide modes. Unlike TE modes, surprisingly, the linear behavior of the TM modes depends on the sign of the wave number kz. The negative kz has a much stronger linear efficiency than that of the positive kz. The bunching mechanism analysis further exhibits that the azimuthal bunching and axial bunching do not compete but cooperate with each other for the backward-wave operation (negative kz). The current findings are encouraging and imply that TM modes might be advantageous to the gyrotron backward-wave oscillators.

Reservoir-engineered entanglement in a hybrid modulated three-mode optomechanical system

NASA Astrophysics Data System (ADS)

Liao, Chang-Geng; Chen, Rong-Xin; Xie, Hong; Lin, Xiu-Min

2018-04-01

We propose an effective approach for generating highly pure and strong cavity-mechanical entanglement (or optical-microwave entanglement) in a hybrid modulated three-mode optomechanical system. By applying two-tone driving to the cavity and modulating the coupling strength between two mechanical oscillators (or between a mechanical oscillator and a transmission line resonator), we obtain an effective Hamiltonian where an intermediate mechanical mode acting as an engineered reservoir cools the Bogoliubov modes of two target system modes via beam-splitter-like interactions. In this way, the two target modes are driven to two-mode squeezed states in the stationary limit. In particular, we discuss the effects of cavity-driving detuning on the entanglement and the purity. It is found that the cavity-driving detuning plays a critical role in the goal of acquiring highly pure and strongly entangled steady states.

Orbital angular momentum mode of Gaussian beam induced by atmospheric turbulence

NASA Astrophysics Data System (ADS)

Cheng, Mingjian; Guo, Lixin; Li, Jiangting; Yan, Xu; Dong, Kangjun

2018-02-01

Superposition theory of the spiral harmonics is employed to numerical study the transmission property of the orbital angular momentum (OAM) mode of Gaussian beam induced by atmospheric turbulence. Results show that Gauss beam does not carry OAM at the source, but various OAM modes appear after affected by atmospheric turbulence. With the increase of atmospheric turbulence strength, the smaller order OAM modes appear firstly, followed by larger order OAM modes. The beam spreading of Gauss beams in the atmosphere enhance with the increasing topological charge of the OAM modes caused by atmospheric turbulence. The mode probability density of the OAM generated by atmospheric turbulence decreases, and peak position gradually deviate from the Gauss beam spot center with the increase of the topological charge. Our results may be useful for improving the performance of long distance laser digital spiral imaging system.

Dishwasher For Earth Or Outer Space

NASA Technical Reports Server (NTRS)

Tromble, Jon D.

1991-01-01

Dishwashing machine cleans eating utensils in either Earth gravity or zero gravity of outer space. Cycle consists of three phases: filling, washing, and draining. Rotation of tub creates artificial gravity aiding recirculation of water during washing phase in absence of true gravity. Centrifugal air/water separator helps system function in zero gravity. Self-cleaning filter contains interdigitating blades catching solid debris when water flows between them. Later, blades moved back and forth in scissor-like manner to dislodge debris, removed by backflow of water.

How to build a model illustrating sea-floor spreading and subduction

USGS Publications Warehouse

Lahr, J.C.

1999-01-01

This report describes how to build a model of the outer 300 km (180 miles) of the Earth that can be used to develop a better understanding of the principal features of plate tectonics, including sea-floor spreading, the pattern of magnetic stripes frozen into the sea floor, transform faulting, thrust faulting, subduction, and volcanism. In addition to a paper copy of this report, the materials required are a cardboard shoebox, glue, scissors, straight edge, and safety razor blade.

Passive PE Sampling in Support of In Situ Remediation of Contaminated Sediments: Standard Operating Procedure for PE Analysis

DTIC Science & Technology

2012-12-01

4.5 Food-grade aluminum foil 4.6 Stainless steel forceps 4.7 Single-edge razor blades 4.8 Teflon (or similar non-contaminating material) cutting...handling PE to avoid cross-contaminating the PE. 6.3 Methylene chloride (pesticide grade) rinsed, stainless steel forceps and scissors are used...3.1 PE is susceptible to contamination from atmospheric and surfaces, and so it must be handled using clean techniques. 3.2 While the formation of

Astronaut Rhea Seddon works on flyswatter-like snagging device

NASA Technical Reports Server (NTRS)

1985-01-01

Astronaut Rhea Seddon begins works on flyswatter-like snagging device to be used as an extension to the remote manipulator system (RMS) arm on Discovery for an attempt to trip a lever on the troubled Syncom-IV satellite. She is seated on the floor of the aft flight deck with a pair of scissors in her mouth. She is using an exacto knife to cut the extension out of plastic. Her jacket is floating in the bottom right edge of the frame.

Effect of epidemic spreading on species coexistence in spatial rock-paper-scissors games.

PubMed

Wang, Wen-Xu; Lai, Ying-Cheng; Grebogi, Celso

2010-04-01

A fundamental question in nonlinear science and evolutionary biology is how epidemic spreading may affect coexistence. We address this question in the framework of mobile species under cyclic competitions by investigating the roles of both intra- and interspecies spreading. A surprising finding is that intraspecies infection can strongly promote coexistence while interspecies spreading cannot. These results are quantified and a theoretical paradigm based on nonlinear partial differential equations is derived to explain the numerical results.

Research on Method of Interactive Segmentation Based on Remote Sensing Images

NASA Astrophysics Data System (ADS)

Yang, Y.; Li, H.; Han, Y.; Yu, F.

2017-09-01

In this paper, we aim to solve the object extraction problem in remote sensing images using interactive segmentation tools. Firstly, an overview of the interactive segmentation algorithm is proposed. Then, our detailed implementation of intelligent scissors and GrabCut for remote sensing images is described. Finally, several experiments on different typical features (water area, vegetation) in remote sensing images are performed respectively. Compared with the manual result, it indicates that our tools maintain good feature boundaries and show good performance.

The Effect of SnCl2/AmF Pretreatment on Short- and Long-Term Bond Strength to Eroded Dentin

PubMed Central

Zumstein, Katrin; Peutzfeldt, Anne; Lussi, Adrian

2018-01-01

This study investigated the effect of SnCl2/AmF pretreatment on short- and long-term bond strength of resin composite to eroded dentin mediated by two self-etch, MDP-containing adhesive systems. 184 dentin specimens were produced from extracted human molars. Half the specimens (n = 92) were artificially eroded, and half were left untreated. For both substrates, half the specimens were pretreated with SnCl2/AmF, and half were left untreated. The specimens were treated with Clearfil SE Bond or Scotchbond Universal prior to application of resin composite. Microtensile bond strength (μTBS) was measured after 24 h or 1 year. Failure mode was detected and EDX was performed. μTBS results were statistically analyzed (α = 0.05). μTBS was significantly influenced by the dentin substrate (eroded < noneroded dentin) and storage time (24 h > 1 year; p < 0.0001) but not by pretreatment with SnCl2/AmF or adhesive system. The predominant failure mode was adhesive failure at the dentin-adhesive interface. The content of Sn was generally below detection limit. Pretreatment with SnCl2/AmF did not influence short- and long-term bond strength to eroded dentin. Bond strength was reduced after storage for one year, was lower to eroded dentin than to noneroded dentin, and was similar for the two adhesive systems.

Characterization of Pu-238 Heat Source Granule Containment

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

Richardson, Paul Dean II; Sanchez, Joey Leo; Wall, Angelique Dinorah

The Milliwatt Radioisotopic Themoelectric Generator (RTG) provides power for permissive-action links. Essentially these are nuclear batteries that convert thermal energy to electrical energy using a doped silicon-germanium thermopile. The thermal energy is provided by a heat source made of 238Pu, in the form of 238PuO 2 granules. The granules are contained by 3 layers of encapsulation. A thin T-111 liner surrounds the 238PuO 2 granules and protects the second layer (strength member) from exposure to the fuel granules. An outer layer of Hastalloy-C protects the T-111 from oxygen embrittlement. The T-111 strength member is considered the critical component in thismore » 238PuO 2 containment system. Any compromise in the strength member seen during destructive testing required by the RTG surveillance program is characterized. The T-111 strength member is characterized through Scanning Electron Microscopy (SEM), and Metallography. SEM is used in the Secondary Electron mode to reveal possible grain boundary deformation and/or cracking in the region of the strength member weld. Deformation and cracking uncovered by SEM are further characterized by Metallography. Metallography sections are mounted and polished, observed using optical microscopy, then documented in the form of microphotographs. SEM mat further be used to examine polished Metallography mounts to characterize elements using the SEM mode of Energy Dispersive X-ray spectroscopy (EDS).« less

Microstructure and rheology of thermoreversible nanoparticle gels.

PubMed

Ramakrishnan, S; Zukoski, C F

2006-08-29

Naïve mode coupling theory is applied to particles interacting with short-range Yukawa attractions. Model results for the location of the gel line and the modulus of the resulting gels are reduced to algebraic equations capturing the effects of the range and strength of attraction. This model is then applied to thermo reversible gels composed of octadecyl silica particles suspended in decalin. The application of the model to the experimental system requires linking the experimental variable controlling strength of attraction, temperature, to the model strength of attraction. With this link, the model predicts temperature and volume fraction dependencies of gelation and modulus with five parameters: particle size, particle volume fraction, overlap volume of surface hairs, and theta temperature. In comparing model predictions with experimental results, we first observe that in these thermal gels there is no evidence of clustering as has been reported in depletion gels. One consequence of this observation is that there are no additional adjustable parameters required to make quantitative comparisons between experimental results and model predictions. Our results indicate that the naïve mode coupling approach taken here in conjunction with a model linking temperature to strength of attraction provides a robust approach for making quantitative predictions of gel mechanical properties. Extension of model predictions to additional experimental systems requires linking experimental variables to the Yukawa strength and range of attraction.

Evaluating the bonding of two adhesive systems to enamel submitted to whitening dentifrices.

PubMed

Briso, André Luiz Fraga; Toseto, Roberta Mariano; de Arruda, Alex Mendes; Tolentino, Patricia Ramos; de Alexandre, Rodrigo Sversut; dos Santos, Paulo Henrique

2010-01-01

The aim of this study was to evaluate by micro-shear bond strength test, the bond strength of composite resin restoration to enamel submitted to whitening dentifrices. Forty bovine teeth were embedded in polystyrene resin and polished. The specimens were randomly divided into eight groups (n=5), according to the dentifrice (carbamide peroxide, hydrogen peroxide and conventional dentifrice) and the adhesive system (Prime & Bond 2.1 and Adper Single Bond 2). Dentifrice was applied for 15 minutes a day, for 21 days. Thirty minutes after the last exposure to dentifrice, the samples were submitted to a bonding procedure with the respective adhesive system. After that, four buttons of resin were bonded in each sample using transparent cylindrical molds. After 24 hours, the teeth were submitted to the micro-shear bond strength test and subsequent analysis of the fracture mode. Data were submitted to analysis of variance and Fisher's PLSD test (alpha = 0.05). The micro-shear bond strength showed no difference between adhesives systems but a significant reduction was found between the control and carbamide groups (p = 0.0145) and the control and hydrogen groups (p = 0.0370). The evaluation of the failures modes showed that adhesive failures were predominant. Cohesive failures were predominant in group IV The use of dentifrice with peroxides can decrease bonding strength in enamel.

Reynolds-number-dependent dynamical transitions on hydrodynamic synchronization modes of externally driven colloids

NASA Astrophysics Data System (ADS)

Oyama, Norihiro; Teshigawara, Kosuke; Molina, John Jairo; Yamamoto, Ryoichi; Taniguchi, Takashi

2018-03-01

The collective dynamics of externally driven Np-colloidal systems (1 ≤Np≤4 ) in a confined viscous fluid have been investigated using three-dimensional direct numerical simulations with fully resolved hydrodynamics. The dynamical modes of collective particle motion are studied by changing the particle Reynolds number as determined by the strength of the external driving force and the confining wall distance. For a system with Np=3 , we found that at a critical Reynolds number a dynamical mode transition occurs from the doublet-singlet mode to the triplet mode, which has not been reported experimentally. The dynamical mode transition was analyzed in detail from the following two viewpoints: (1) spectrum analysis of the time evolution of a tagged particle velocity and (2) the relative acceleration of the doublet cluster with respect to the singlet particle. For a system with Np=4 , we found similar dynamical mode transitions from the doublet-singlet-singlet mode to the triplet-singlet mode and further to the quartet mode.

Reynolds-number-dependent dynamical transitions on hydrodynamic synchronization modes of externally driven colloids.

PubMed

Oyama, Norihiro; Teshigawara, Kosuke; Molina, John Jairo; Yamamoto, Ryoichi; Taniguchi, Takashi

2018-03-01

The collective dynamics of externally driven N_{p}-colloidal systems (1≤N_{p}≤4) in a confined viscous fluid have been investigated using three-dimensional direct numerical simulations with fully resolved hydrodynamics. The dynamical modes of collective particle motion are studied by changing the particle Reynolds number as determined by the strength of the external driving force and the confining wall distance. For a system with N_{p}=3, we found that at a critical Reynolds number a dynamical mode transition occurs from the doublet-singlet mode to the triplet mode, which has not been reported experimentally. The dynamical mode transition was analyzed in detail from the following two viewpoints: (1) spectrum analysis of the time evolution of a tagged particle velocity and (2) the relative acceleration of the doublet cluster with respect to the singlet particle. For a system with N_{p}=4, we found similar dynamical mode transitions from the doublet-singlet-singlet mode to the triplet-singlet mode and further to the quartet mode.

Simulation of transverse modes with their intrinsic Landau damping for bunched beams in the presence of space charge

DOE PAGES

Macridin, Alexandru; Burov, Alexey; Stern, Eric; ...

2015-07-22

Transverse dipole modes in bunches with space charge are simulated using the synergia accelerator modeling package and analyzed with dynamic mode decomposition. The properties of the first three space charge modes, including their shape, damping rates, and tune shifts are described over the entire range of space charge strength. As a result, the intrinsic Landau damping predicted and estimated in 2009 by one of the authors is confirmed with a reasonable scaling factor of ≃2.4. For the KV distribution, very good agreement with PATRIC simulations performed by Kornilov and Boine-Frankenheim is obtained.

Effect on cosmic microwave background polarization of coupling of quintessence to pseudoscalar formed from the electromagnetic field and its dual.

PubMed

Liu, Guo-Chin; Lee, Seokcheon; Ng, Kin-Wang

2006-10-20

We present the full set of power spectra of cosmic microwave background (CMB) temperature and polarization anisotropies due to the coupling between quintessence and pseudoscalar of electromagnetism. This coupling induces a rotation of the polarization plane of the CMB, thus resulting in a nonvanishing B mode and parity-violating TB and EB modes. Using the BOOMERANG data from the flight of 2003, we derive the most stringent constraint on the coupling strength. We find that in some cases the rotation-induced B mode can confuse the hunting for the gravitational lensing-induced B mode.

Effect of metal primers on bond strength of resin cements to base metals.

PubMed

Fonseca, Renata Garcia; de Almeida, Juliana Gomes dos Santos Paes; Haneda, Isabella Gagliardi; Adabo, Gelson Luis

2009-04-01

A strong and durable bond between a metal framework and a resin-based luting agent is desired. Metal primers have been shown to be very effective on noble alloys. However, there is insufficient information about their effect on base metals. The purpose of this study was to evaluate the effect of metal primers on the shear bond strength of resin cements to base metals. A total of 160 cast commercially pure titanium (CP Ti) and NiCr alloy (VeraBond II) disks were embedded in a polyvinyl chloride ring, and their surfaces were smoothed with silicon carbide papers (320, 400, and 600 grit) and airborne-particle abraded with 50-mum aluminum oxide. Specimens of each metal were divided into 4 groups (n=20), which received one of the following luting techniques: (1) Panavia F, (2) Alloy Primer plus Panavia F, (3) Bistite II DC, or (4) Metaltite plus Bistite II DC. Forty minutes after preparation, all specimens were stored in distilled water at 37 degrees C for 24 hours and then thermal cycled (1000 cycles, 5-55 degrees C). After thermal cycling, the specimens were stored in 37 degrees C distilled water for an additional 24 hours or 6 months before being tested in shear mode. Data (MPa) were analyzed using 3-way ANOVA and the post hoc Tukey test (alpha=.05). Each specimen was examined under an optical microscope (x30), and the failure mode was classified as adhesive, cohesive, or a combination of these. The only significant difference between the Panavia F and Alloy Primer plus Panavia F groups occurred in the NiCr alloy at 24 hours, at which point Panavia F demonstrated superior bond strength compared to Alloy Primer plus Panavia F (P<.001). The Bistite II DC and Metaltite plus Bistite II DC groups were not significantly different. The Bistite II DC and Metaltite plus Bistite II DC groups demonstrated significantly lower bond strength to CP Ti (P<.001) than the Panavia F and Alloy Primer plus Panavia F groups, and significantly lower bond strength to NiCr alloy (P<.001) than Panavia F. The Panavia F (P<.01) and Alloy Primer plus Panavia F groups' bond strength to titanium presented a significant increase (P<.001) in shear bond strength at 6 months. In general, the groups exhibited higher shear bond strength to CP Ti than to NiCr alloy (P<.01). The failure mode was 100% adhesive for all groups. The metal primers did not promote an increase in adhesive bonding of resin cements to NiCr alloy and to CP Ti. Water storage had no adverse effect on the shear bond strength of the groups. The shear bond strengths to titanium were significantly higher than those to the NiCr alloy.

Effects of oxygen plasma treatment power on Aramid fiber III/BMI composite humidity resistance properties

NASA Astrophysics Data System (ADS)

Wang, Jing; Shi, Chen; Feng, Jiayue; Long, Xi; Meng, Lingzhi; Ren, Hang

2018-01-01

The effects of oxygen plasma treatment power on Aramid Fiber III chemical structure and its reinforced bismaleimides (BMI) composite humidity resistance properties were investigated in this work. The aramid fiber III chemical structure under different plasma treatment power were measured by FTIR. The composite bending strength and interlinear shear strength with different plasma treatment power before and after absorption water were tested respectively. The composite rupture morphology was observed by SEM. The FTIR results showed that oxygen plasma treatment do not change the fiber bulk chemical structure. The composite humidity resistance of bending strength and interlinear shear strength are similar for untreated and plasma treated samples. The retention rate of composite bending strength and interlinear shear strength are about 75% and 94%, respectively. The composite rupture mode turns to be the fiber failure after water absorption.

'Unconventional' coordination chemistry by metal chelating fragments in a metalloprotein active site.

PubMed

Martin, David P; Blachly, Patrick G; Marts, Amy R; Woodruff, Tessa M; de Oliveira, César A F; McCammon, J Andrew; Tierney, David L; Cohen, Seth M

2014-04-09

The binding of three closely related chelators: 5-hydroxy-2-methyl-4H-pyran-4-thione (allothiomaltol, ATM), 3-hydroxy-2-methyl-4H-pyran-4-thione (thiomaltol, TM), and 3-hydroxy-4H-pyran-4-thione (thiopyromeconic acid, TPMA) to the active site of human carbonic anhydrase II (hCAII) has been investigated. Two of these ligands display a monodentate mode of coordination to the active site Zn(2+) ion in hCAII that is not recapitulated in model complexes of the enzyme active site. This unprecedented binding mode in the hCAII-thiomaltol complex has been characterized by both X-ray crystallography and X-ray spectroscopy. In addition, the steric restrictions of the active site force the ligands into a 'flattened' mode of coordination compared with inorganic model complexes. This change in geometry has been shown by density functional computations to significantly decrease the strength of the metal-ligand binding. Collectively, these data demonstrate that the mode of binding by small metal-binding groups can be significantly influenced by the protein active site. Diminishing the strength of the metal-ligand bond results in unconventional modes of metal coordination not found in typical coordination compounds or even carefully engineered active site models, and understanding these effects is critical to the rational design of inhibitors that target clinically relevant metalloproteins.

Vibrational dynamics and boson peak in a supercooled polydisperse liquid.

PubMed

Abraham, Sneha Elizabeth; Bagchi, Biman

2010-03-01

Vibrational density of states (VDOS) in a supercooled polydisperse liquid is computed by diagonalizing the Hessian matrix evaluated at the potential energy minima for systems with different values of polydispersity. An increase in polydispersity leads to an increase in the relative population of localized high-frequency modes. At low frequencies, the density of states shows an excess compared to the Debye squared-frequency law, which has been identified with the boson peak. The height of the boson peak increases with polydispersity and shows a rather narrow sensitivity to changes in temperature. While the modes comprising the boson peak appear to be largely delocalized, there is a sharp drop in the participation ratio of the modes that exist just below the boson peak indicative of the quasilocalized nature of the low-frequency vibrations. Study of the difference spectrum at two different polydispersity reveals that the increase in the height of boson peak is due to a population shift from modes with frequencies above the maximum in the VDOS to that below the maximum, indicating an increase in the fraction of the unstable modes in the system. The latter is further supported by the facilitation of the observed dynamics by polydispersity. Since the strength of the liquid increases with polydispersity, the present result provides an evidence that the intensity of boson peak correlates positively with the strength of the liquid, as observed earlier in many experimental systems.

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

Huang, J. Y.; E, J. C.; Huang, J. W.

Impact fracture of single-crystal Si is critical to long-term reliability of electronic devices and solar cells for its wide use as components or substrates in semiconductor industry. Single-crystal Si is loaded along two different crystallographic directions with a split Hopkinson pressure bar integrated with an in situ x-ray imaging and diffraction system. Bulk stress histories are measured, simultaneously with x-ray phase contrast imaging (XPCI) and Laue diffraction. Damage evolution is quantified with grayscale maps from XPCI. Single-crystal Si exhibits pronounced anisotropy in fracture modes, and thus fracture strengths and damage evolution. For loading along [11¯ 0] and viewing along [001],more » (1¯1¯0)[11¯ 0] cleavage is activated and induces horizontal primary cracks followed by perpendicular wing cracks. However, for loading along [011¯] and viewing along [111], random nucleation and growth of shear and tensile-splitting crack networks lead to catastrophic failure of materials with no cleavage. The primary-wing crack mode leads to a lower characteristic fracture strength due to predamage, but a more concentrated strength distribution, i.e., a higher Weibull modulus, compared to the second loading case. Furthermore, the sequential primary cracking, wing cracking and wing-crack coalescence processes result in a gradual increase of damage with time, deviating from theoretical predictions. Particle size and aspect ratios of fragments are discussed with postmortem fragment analysis, which verifies fracture modes observed in XPCI.« less

In situ rock strength and far field stress in the Nankai accretionary complex: Integration of downhole data from multiple wells

NASA Astrophysics Data System (ADS)

Huffman, K. A.; Saffer, D. M.

2014-12-01

Knowing the magnitude of tectonic stress and rock strength at seismically active margins is important towards understanding fault strength and failure mechanics, yet both are difficult to measure in situ. Recent work at subduction margins, including Integrated Ocean Drilling Program (IODP) Nankai Trough Subduction Zone Experiment (NanTroSEIZE) drillsites, uses the width of compressional wellbore breakouts (BO), which depends on far field stress conditions, rock strength, and borehole annular pressure (APRS), to estimate the magnitude of horizontal principal stresses (SHmax and Shmin); estimates are problematic due to uncertainty in rock strength (unconfined compressive strength/UCS- for which direct measurements are scarce) and rheology that govern stress distribution at the wellbore. We conduct a novel case study at IODP Site C0002, where a hole was drilled twice with different boundary conditions, providing an opportunity to define in situ stress and strength from field data. Site C0002 is the main deep riser borehole for NanTroSEIZE, located near the seaward edge of the Kumano Basin above the seismogenic plate boundary, ~30 km from the trench. Several boreholes were drilled at the site. During IODP Expedition 314 in 2007, Hole C0002A was drilled with a suite of logging while drilling (LWD) tools to 1401 mbsf in a riserless mode. Hole C0002F, ~70 m away, was drilled to 862 mbsf in riserless mode during Exp. 326 in 2010 and deepened to 2005 mbsf in a riser mode during Expedition 338 in 2012-2013. Increased APRS achieved by riser drilling stabilizes the borehole and suppresses BO, consistent with resistivity imaging data from Exp. 314 that document well-developed, continuous BO throughout the borehole, and data from Expedition 338 indicating few BO. We use a semi-Newtonian approach to solve for stress and UCS consistent with the observed BO width and measured APRS in the two holes over the interval from 862-2005 mbsf. Effective SHmax ranges from ~10-30 MPa and indicate a strike-slip or thrust regime. Our results indicate UCS is higher than predicted by empirical relations and a small suite of laboratory tests by as much as 20 MPa. This apparent discrepancy may indicate that the failure criterion, or assumed distribution of stresses around the wellbore in analyses of far field stress, may not be appropriate in this setting.

Polarization Dependent Coupling of Whispering Gallery Modes in Microspheres

NASA Technical Reports Server (NTRS)

Adamovsky, G.; Wrbanek, S.; Floyd, B.; Crotty, M.

2010-01-01

Two sets of resonances in glass microspheres attached to a standard communication-grade single-mode optical fiber have been observed. It has been found that the strength of the resonances depends strongly on the polarization of the coupled light. Furthermore, the position of the resonances in the wavelength domain depends on the polarization of light in the optical fiber with maximum magnitudes shifted by approximately 45 .

Do matrix metalloproteinase inhibitors improve the bond durability of universal dental adhesives?

PubMed

Tekçe, Neslihan; Tuncer, Safa; Demirci, Mustafa; Balci, Sibel

2016-11-01

The aim of this study was to evaluate the effects of matrix metalloproteinases (MMPs) inhibitors on the microtensile bond strength (μTBS) and the adhesive-dentin interface of two universal dentin bonding agents, Single Bond Universal and All Bond Universal, after 12 months of water storage. Seventy extracted, caries-free, human third molars were used in this study. Of these, 50 were used for μTBS testing and 20 were used for scanning electron microscopy. The two bonding agents were applied to flat dentin surfaces in five different ways: self-etch mode, etch-and-rinse mode with 37% phosphoric acid, etch-and-rinse mode with phosphoric acid containing 1% benzalkonium chloride, etch-and-rinse mode with phosphoric acid and 2% chlorhexidine, and etch-and-rinse mode with 0.5 M ethylenediaminetetraacetic acid (EDTA) (n = 5 for each bonding agent in each group; N = 50). Half the specimens were subjected to μTBS tests at 24 h, while half were subjected to the tests after 12 months of water storage. For each bonding agent, inhibition, storage, and their interaction effects were tested by two-way analysis of variance and Bonferroni tests. For Single Bond Universal, the benzalkonium chloride (p = 0.024) and chlorhexidine groups (p = 0.033) exhibited significantly higher μTBS values at 24 h compared with the self-etch group. For All Bond Universal, all groups displayed similar bond strengths at 24 h (p > 0.05). After 12 months of water storage, the μTBS values decreased significantly in the benzalkonium chloride group for Single Bond Universal (p = 0.001) and the self-etch (p = 0.029), chlorhexidine (p = 0.046), and EDTA (p = 0.032) groups for All Bond Universal. These results suggest that the immediate dentin bond strength increases when universal bonding systems are applied in the etch-and-rinse mode, although the durability decreases. The use of chlorhexidine and EDTA can increase the bond durability of mild adhesives such as Single Bond Universal. SCANNING 38:535-544, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Localized transversal-rotational modes in linear chains of equal masses.

PubMed

Pichard, H; Duclos, A; Groby, J-P; Tournat, V; Gusev, V E

2014-01-01

The propagation and localization of transversal-rotational waves in a two-dimensional granular chain of equal masses are analyzed in this study. The masses are infinitely long cylinders possessing one translational and one rotational degree of freedom. Two dispersive propagating modes are predicted in this granular crystal. By considering the semi-infinite chain with a boundary condition applied at its beginning, the analytical study demonstrates the existence of localized modes, each mode composed of two evanescent modes. Their existence, position (either in the gap between the propagating modes or in the gap above the upper propagating mode), and structure of spatial localization are analyzed as a function of the relative strength of the shear and bending interparticle interactions and for different boundary conditions. This demonstrates the existence of a localized mode in a semi-infinite monatomic chain when transversal-rotational waves are considered, while it is well known that these types of modes do not exist when longitudinal waves are considered.

Characterization of Pu-238 heat source granule containment

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

Richardson Ii, P D; Thronas, D L; Romero, J P

2008-01-01

The Milliwatt Radioisotopic Thermoelectric Generator (RTG) provides power for permissive-action links. These nuclear batteries convert thermal energy to electrical energy using a doped silicon-germanium thermopile. The thermal energy is provided by a heat source made of {sup 238}Pu, in the form of {sup 238}PuO{sub 2} granules. The granules are contained in 3 layers of encapsulation. A thin T-111 liner surrounds the {sup 238}PuO{sub 2} granules and protects the second layer (strength member) from exposure to the fuel granules. The T-111 strength member contains the fuel under impact condition. An outer clad of Hastelloy-C protects the T-111 from oxygen embrittlement. Themore » T-111 strength member is considered the critical component in this {sup 238}PuO{sub 2} containment system. Any compromise in the strength member is something that needs to be characterized. Consequently, the T-111 strength member is characterized upon it's decommissioning through Scanning Electron Microscopy (SEM), and Metallography. SEM is used in Secondary Electron mode to reveal possible grain boundary deformation and/or cracking in the region of the strength member weld. Deformation and cracking uncovered by SEM are further characterized by Metallography. Metallography sections are mounted and polished, observed using optical microscopy, then documented in the form of photomicrographs. SEM may further be used to examine polished Metallography mounts to characterize elements using the SEM mode of Energy Dispersive X-ray Spectroscopy (EDS). This paper describes the characterization of the metallurgical condition of decommissioned RTG heat sources.« less

Bond Capability of Universal Adhesive Systems to Dentin in Self-etch Mode after Short-term Storage and Cyclic Loading

PubMed Central

Costa, Daniele Morosini; Somacal, Deise Caren; Borges, Gilberto Antonio; Spohr, Ana Maria

2017-01-01

Objective: The aim was to evaluate, in vitro, the tensile bond strength to dentin of Scotchbond Universal (SU), All-Bond Universal (AU) and One Coat 7 Universal (OC7) adhesives applied in self-etch mode, after 24 h of storage and after 500,000 loading cycles, using Clearfil SE Bond (SE) as a control. Materials and Methods: The adhesives were applied on the dentin of bovine teeth, followed by the application of a composite resin. Thirty specimens were obtained for each adhesive. Half of the specimens were submitted to cyclic loading for 500,000 cycles. All specimens were submitted to a tensile bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/minute. Results: According to two-way ANOVA and Tukey’s test (α=5%), the interaction between the adhesive and cyclic loading factors was significant (p=0.001). The means followed by the same letter represent no significant difference in the bond strength (MPa) after 24 h: OC7=7.86A (±2.90), SU=6.78AB (±2.03), AU=5.61BC (±2.32), and SE=3.53C (±1.89). After cyclic loading, SE, SU and AU maintained bond strength comparable to 24 h period. There was a significant decrease only for OC7. Conclusion: SU, AU and OC7 had bond strength to dentin comparable to that of SE. Only OC7 had decreased bond strength to dentin after cyclic loading. PMID:28839476

The effect of storage conditions, contamination modes and cleaning procedures on the resin bond strength to lithium disilicate ceramic.

PubMed

Klosa, Karsten; Wolfart, Stefan; Lehmann, Frank; Wenz, Hans-Jürgen; Kern, Matthias

2009-04-01

The purpose of this in-vitro study was to evaluate the resin bond strength to pre-etched lithium disilicate ceramic using different cleaning methods after two contamination modes (saliva or saliva and silicone). Plexiglas tubes filled with composite resin (MultiCore Flow) were bonded to etched and silanized ceramic disks made of lithium disilicate ceramic (IPS e.max Press) using a luting resin (Multilink Automix). Either etched or unetched ceramic surfaces were contaminated with saliva or with saliva followed by a disclosing silicone. Groups of 16 specimens each were bonded after pretreatment using 4 surface cleaning agents (37% phosphoric acid, 5% hydrofluoric acid, 96% isopropanol, air polishing device with sodium bicarbonate) in different combinations. Before measuring tensile bond strength, specimens were stored for 3 or 150 days with thermocycling. After 150 days of storage, etching of saliva-contaminated surfaces with 5% hydrofluoric acid and/or 37% phosphoric acid provided statistically significantly higher bond strengths (37.9 to 49.5 MPa) than the other cleaning methods (1.7 to 15.5 MPa). After saliva and silicone contamination, etching with 5% hydrofluoric acid provided statistically significantly higher bond strengths (44.5 to 50.3 MPa) than all other cleaning methods (0.3 to 13.5 MPa). Ceramic cleaning methods after try-in procedures have a significant influence on the resin bond strength and are dependent on the type of contamination. Re-etching lithium disilicate ceramic with 5% hydrofluoric acid is most effective in removing contamination with saliva and/or a silicone disclosing medium.

Effects of moisture conditions of dental enamel surface on bond strength of brackets bonded with moisture-insensitive primer adhesive system.

PubMed

Endo, Toshiya; Ozoe, Rieko; Sanpei, Sugako; Shinkai, Koichi; Katoh, Yoshiroh; Shimooka, Shohachi

2008-07-01

The purposes of this study were to evaluate the effects of different degrees of water contamination on the shear bond strength of orthodontic brackets bonded to dental enamel with a moisture-insensitive primer (MIP) adhesive system and to compare the modes of bracket/adhesive failure. A total of 68 human premolars were divided into four groups by primers and enamel surface conditions (desiccated, blot dry, and overwet). In group I, the hydrophobic Transbond XT primer adhesive system was used under desiccated conditions for bonding the brackets; in group II, the hydrophilic Transbond MIP adhesive system was used under desiccated conditions; in group III, the hydrophilic Transbond MIP adhesive system was used under blot dry conditions; and in group IV, the hydrophilic Transbond MIP adhesive system was used under overwet conditions. Shear bond strength was measured with a universal testing machine, and the mode of bracket/adhesive failure was determined according to the adhesive remnant index. The mean shear bond strengths were not significantly different among groups I, II, and III, and were higher than the clinically required range of 6 to 8 MPa. The mean shear bond strength achieved in group IV was significantly lower than that achieved in groups I, II, and III, and also lower than the clinically required values. Bond failure occurred at the enamel-adhesive interface more frequently in group IV than in groups I and III. To achieve clinically sufficient bond strengths with the hydrophilic MIP adhesive system, excess water should be blotted from the water-contaminated enamel surface.

Is muscular strength balance influenced by menstrual cycle in female soccer players?

PubMed

Dos Santos Andrade, Marília; Mascarin, Naryana C; Foster, Roberta; de Jármy di Bella, Zsuzsanna I; Vancini, Rodrigo L; Barbosa de Lira, Claudio A

2017-06-01

Muscular strength imbalance is an important risk factor for ACL injury, but it is not clear the impact of menstrual cycle on muscular strength balance. Our aims were to compare muscular balance (hamstring-to-quadriceps peak torque strength balance ratio) between luteal and follicular phases and compare gender differences relative to strength balance to observe possible fluctuations in strength balance ratio. Thirty-eight soccer athletes (26 women and 12 men) took part in this study. Athletes participated in two identical isokinetic strength evaluations for both knee (non-dominant [ND] and dominant [D]). Peak torque for quadriceps and hamstring muscles were measured in concentric mode and hamstring-to-quadriceps peak torque strength balance ratio calculated. Women had significantly lower hamstring-to-quadriceps peak torque strength balance ratio during the follicular compared to luteal phase, for the ND limb (P=0.011). However, no differences, between luteal and follicular phases, were observed in the D limb. In men, no difference in strength balance ratios was found between the ND and D limbs. These data may be useful in prevention programs for knee (ACL) injuries among soccer female athletes.

Comparison of tensile strength among simple interrupted, cruciate, intradermal, and subdermal suture patterns for incision closure in ex vivo canine skin specimens.

PubMed

Zellner, Eric M; Hedlund, Cheryl S; Kraus, Karl H; Burton, Andrew F; Kieves, Nina R

2016-06-15

OBJECTIVE To compare suture placement time, tension at skin separation and suture line failure, and mode of failure among 4 suture patterns. DESIGN Randomized trial. SAMPLE 60 skin specimens from the pelvic limbs of 30 purpose-bred Beagles. PROCEDURES Skin specimens were harvested within 2 hours after euthanasia and tested within 6 hours after harvest. An 8-cm incision was made in each specimen and sutured with 1 of 4 randomly assigned suture patterns (simple interrupted, cruciate, intradermal, or subdermal). Suture placement time and percentage of skin apposition were evaluated. Specimens were mounted in a calibrated material testing machine and distracted until suture line failure. Tensile strength at skin-edge separation and suture-line failure and mode of failure were compared among the 4 patterns. RESULTS Mean suture placement time for the cruciate pattern was significantly less than that for other patterns. Percentage of skin apposition did not differ among the 4 patterns. Mean tensile strength at skin-edge separation and suture-line failure for the simple interrupted and cruciate patterns were significantly higher than those for the intradermal and subdermal patterns. Mean tensile strength at skin-edge separation and suture-line failure did not differ significantly between the intradermal and subdermal patterns or the simple interrupted and cruciate patterns. The primary mode of failure for the simple interrupted pattern was suture breakage, whereas that for the cruciate, intradermal, and subdermal patterns was tissue failure. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested external skin sutures may be preferred for closure of incisions under tension to reduce risk of dehiscence.

Failure Characteristics of Granite Influenced by Sample Height-to-Width Ratios and Intermediate Principal Stress Under True-Triaxial Unloading Conditions

NASA Astrophysics Data System (ADS)

Li, Xibing; Feng, Fan; Li, Diyuan; Du, Kun; Ranjith, P. G.; Rostami, Jamal

2018-05-01

The failure modes and peak unloading strength of a typical hard rock, Miluo granite, with particular attention to the sample height-to-width ratio (between 2 and 0.5), and the intermediate principal stress was investigated using a true-triaxial test system. The experimental results indicate that both sample height-to-width ratios and intermediate principal stress have an impact on the failure modes, peak strength and severity of rockburst in hard rock under true-triaxial unloading conditions. For longer rectangular specimens, the transition of failure mode from shear to slabbing requires higher intermediate principal stress. With the decrease in sample height-to-width ratios, slabbing failure is more likely to occur under the condition of lower intermediate principal stress. For same intermediate principal stress, the peak unloading strength monotonically increases with the decrease in sample height-to-width. However, the peak unloading strength as functions of intermediate principal stress for different types of rock samples (with sample height-to-width ratio of 2, 1 and 0.5) all present the pattern of initial increase, followed by a subsequent decrease. The curves fitted to octahedral shear stress as a function of mean effective stress also validate the applicability of the Mogi-Coulomb failure criterion for all considered rock sizes under true-triaxial unloading conditions, and the corresponding cohesion C and internal friction angle φ are calculated. The severity of strainburst of granite depends on the sample height-to-width ratios and intermediate principal stress. Therefore, different supporting strategies are recommended in deep tunneling projects and mining activities. Moreover, the comparison of test results of different σ 2/ σ 3 also reveals the little influence of minimum principal stress on failure characteristics of granite during the true-triaxial unloading process.

Application of albumin protein and indocyanine green chromophore for tissue soldering by using an IR diode laser: ex vivo and in vivo studies.

PubMed

Khosroshahi, M E; Nourbakhsh, M S; Saremi, S; Hooshyar, A; Rabbani, Sh; Tabatabai, F; Anvari, M Sotudeh

2010-12-01

We sought to examine the impact of different parameters of laser soldering on the thermophysical properties of the skin and to optimize these parameters for sealing a full-thickness incision in the rat skin under closed feedback control under in vivo conditions. Laser tissue soldering based on protein as biologic glues and other compounds can provide greater bond strength and less collateral damage. Endogenous and exogenous materials such as indocyanine green (ICG) are often added to solders to enhance light absorption. In ex vivo study, the temperature increase, number of scan (Ns), and scan velocity (Vs) were investigated. In ex vivo studies, four skin incisions were made over rat dorsa and were closed by using two different methods: (a) wound closure by suture and (b) closure by using an automated temperature-controlled system. An automated soldering system was developed based on a diode laser, IR detector, photodiode, digital thermocouple, and camera. The true temperature of heated tissue was determined by using a calibration software method. The results showed that at each laser irradiance (I), the tensile strength (σ) of incisions repaired in the static mode is higher than in the dynamic mode. It must also be noted that the tensile strength of the repaired skin wound was increased by increasing the irradiance in both static and dynamic modes. However, in parallel, an increase in the corresponding temperature was observed. The tensile strength was measured for sutured and laser-soldered tissue after 2 to 10 postoperative days. Histopathologic studies showed a better healing and less inflammatory reactions than with those caused by standard sutures after day 7. It is demonstrated that automated laser soldering technique can be practical provided the optothermal properties of tissue is carefully optimized.

DESENSITIZING BIOACTIVE AGENTS IMPROVES BOND STRENGTH OF INDIRECT RESIN-CEMENTED RESTORATIONS: PRELIMINARY RESULTS

PubMed Central

Pires-De-Souza, Fernanda de Carvalho Panzeri; de Marco, Fabíola Fiorezi; Casemiro, Luciana Assirati; Panzeri, Heitor

2007-01-01

Objective: The aim of this study was to assess the bond strength of indirect composite restorations cemented with a resin-based cement associated with etch-and-rinse and self-etching primer adhesive systems to dentin treated or not with a bioactive material. Materials and Method: Twenty bovine incisor crowns had the buccal enamel removed and the dentin ground flat. The teeth were assigned to 4 groups (n=5): Group I: acid etching + Prime & Bond NT (Dentsply); Group II: application of a bioactive glass (Biosilicato®)+ acid etching + Prime & Bond NT; Group III: One-up Bond F (J Morita); Group IV: Biosilicato® + One-up Bond F. Indirect composite resin (Artglass, Kulzer) cylinders (6x10mm) were fabricated and cemented to the teeth with a dualcure resin-based cement (Enforce, Dentsply). After cementation, the specimens were stored in artificial saliva at 37oC for 30 days and thereafter tested in tensile strength in a universal testing machine (EMIC) with 50 kgf load cell at a crosshead speed of 1 mm/min. Failure modes were assessed under scanning electron microscopy. Data were analyzed statistically by ANOVA and Tukey's test (95% level of confidence). Results: Groups I, II and III had statistically similar results (p>0.05). Group IV had statistically significant higher bond strength means (p<0.05) than the other groups. The analysis of the debonded surfaces showed a predominance of adhesive failure mode for Group III and mixed failure mode for the other groups. Conclusion: The use of desensitizing agent did not affect negatively the bonding of the indirect composite restorations to dentin, independently of the tested adhesive systems. PMID:19089114

Collaboration of doctors and nurses with ethnomedical practitioners.

PubMed

Bastien, J W

1994-01-01

In Bolivia, workshops serve as a means for biomedical practitioners and Aymara and Quechua ethnomedical practitioners from the Andes to share information about illnesses. The traditional practitioners demonstrate and biomedical personnel participate in curing rituals. Joint therapy sessions and development of joint strategies to improve health are included. Participants list the names, symptoms, causes, and treatments of diarrhea in a column for ethnomedicine and another for biomedicine. Biomedical and ethnomedical practitioners work together to persuade indigenous peoples to overcome their fear of and resistance to vaccination. One way to achieve this is by having people examine unsterilized knives under the microscope to see the tetanus toxoid. Physicians tend not to respect midwives and traditional birth attendants (TBAs). Biomedical trainers are not trained in and/or undervalue ethnomedicine, and can introduce midwives and TBAs to unhealthy practices. For example, they insist on scissors to cut the umbilical cord, but scissors are hard to sterilize, resulting in increased rates of neonatal tetanus. Women trained in medical anthropology, cross-cultural communication, and public health are the best trainers of TBAs and midwives. Supervision is needed to integrate TBAs and midwives into health programs and to improve their skills. Herbalism and ritual healing are more popular than the rural health care delivery system. Integrated clinics attract more clients than standard clinics. Recommended guidelines on collaboration revolve around recognition and respect of traditional healers, rewards for biomedical and ethnomedical personnel who collaborate, and issuance of health cards so both sets of practitioners can view patients' medical histories.

Vibration control of an energy regenerative seat suspension with variable external resistance

NASA Astrophysics Data System (ADS)

Ning, Donghong; Sun, Shuaishuai; Du, Haiping; Li, Weihua; Zhang, Nong

2018-06-01

In this paper, an energy regenerative seat suspension with a variable external resistance is proposed and built, and a semi-active controller for its vibration control is also designed and validated. The energy regenerative seat suspension is built with a three-phase generator and a gear reducer, which are installed in the scissors structure centre of the seat suspension, and the vibration energy is directly harvested from the rotary movement of suspension's scissors structure. The electromagnetic torque of the semi-active seat suspension actuator is controlled by an external variable resistor. An integrated model including the seat suspension's kinematics and the generator is built and proven to match the test result very well. A simplified experimental phenomenon model is also built based on the test results for the controller design. A state feedback H∞ controller is proposed for the regenerative seat suspension's semi-active vibration control. The proposed regenerative seat suspension and its controller are validated with both simulations and experiments. A well-tuned passive seat suspension is applied to evaluate the regenerative seat's performance. Based on ISO 2631-1, the frequency-weighted root mean square (FW-RMS) acceleration of the proposed seat suspension has a 22.84% reduction when compared with the passive one, which indicates the improvement of ride comfort. At the same time, the generated RMS power is 1.21 W. The proposed regenerative seat suspension can greatly improve the driver's ride comfort and has the potential to be developed to a self-powered semi-active system.

Optimal actuator location within a morphing wing scissor mechanism configuration

NASA Astrophysics Data System (ADS)

Joo, James J.; Sanders, Brian; Johnson, Terrence; Frecker, Mary I.

2006-03-01

In this paper, the optimal location of a distributed network of actuators within a scissor wing mechanism is investigated. The analysis begins by developing a mechanical understanding of a single cell representation of the mechanism. This cell contains four linkages connected by pin joints, a single actuator, two springs to represent the bidirectional behavior of a flexible skin, and an external load. Equilibrium equations are developed using static analysis and the principle of virtual work equations. An objective function is developed to maximize the efficiency of the unit cell model. It is defined as useful work over input work. There are two constraints imposed on this problem. The first is placed on force transferred from the external source to the actuator. It should be less than the blocked actuator force. The other is to require the ratio of output displacement over input displacement, i.e., geometrical advantage (GA), of the cell to be larger than a prescribed value. Sequential quadratic programming is used to solve the optimization problem. This process suggests a systematic approach to identify an optimum location of an actuator and to avoid the selection of location by trial and error. Preliminary results show that optimum locations of an actuator can be selected out of feasible regions according to the requirements of the problem such as a higher GA, a higher efficiency, or a smaller transferred force from external force. Results include analysis of single and multiple cell wing structures and some experimental comparisons.

Evolution of restraint in a structured rock–paper–scissors community

PubMed Central

Nahum, Joshua R.; Harding, Brittany N.; Kerr, Benjamin

2011-01-01

It is not immediately clear how costly behavior that benefits others evolves by natural selection. By saving on inherent costs, individuals that do not contribute socially have a selective advantage over altruists if both types receive equal benefits. Restrained consumption of a common resource is a form of altruism. The cost of this kind of prudent behavior is that restrained individuals give up resources to less-restrained individuals. The benefit of restraint is that better resource management may prolong the persistence of the group. One way to dodge the problem of defection is for altruists to interact disproportionately with other altruists. With limited dispersal, restrained individuals persist because of interaction with like types, whereas it is the unrestrained individuals that must face the negative long-term consequences of their rapacity. Here, we study the evolution of restraint in a community of three competitors exhibiting a nontransitive (rock–paper–scissors) relationship. The nontransitivity ensures a form of negative feedback, whereby improvement in growth of one competitor has the counterintuitive consequence of lowering the density of that improved player. This negative feedback generates detrimental long-term consequences for unrestrained growth. Using both computer simulations and evolution experiments with a nontransitive community of Escherichia coli, we find that restrained growth can evolve under conditions of limited dispersal in which negative feedback is present. This research, thus, highlights a set of ecological conditions sufficient for the evolution of one form of altruism. PMID:21690371

Evolution of restraint in a structured rock-paper-scissors community.

PubMed

Nahum, Joshua R; Harding, Brittany N; Kerr, Benjamin

2011-06-28

It is not immediately clear how costly behavior that benefits others evolves by natural selection. By saving on inherent costs, individuals that do not contribute socially have a selective advantage over altruists if both types receive equal benefits. Restrained consumption of a common resource is a form of altruism. The cost of this kind of prudent behavior is that restrained individuals give up resources to less-restrained individuals. The benefit of restraint is that better resource management may prolong the persistence of the group. One way to dodge the problem of defection is for altruists to interact disproportionately with other altruists. With limited dispersal, restrained individuals persist because of interaction with like types, whereas it is the unrestrained individuals that must face the negative long-term consequences of their rapacity. Here, we study the evolution of restraint in a community of three competitors exhibiting a nontransitive (rock-paper-scissors) relationship. The nontransitivity ensures a form of negative feedback, whereby improvement in growth of one competitor has the counterintuitive consequence of lowering the density of that improved player. This negative feedback generates detrimental long-term consequences for unrestrained growth. Using both computer simulations and evolution experiments with a nontransitive community of Escherichia coli, we find that restrained growth can evolve under conditions of limited dispersal in which negative feedback is present. This research, thus, highlights a set of ecological conditions sufficient for the evolution of one form of altruism.

Custom-Designed Molecular Scissors for Site-Specific Manipulation of the Plant and Mammalian Genomes

NASA Astrophysics Data System (ADS)

Kandavelou, Karthikeyan; Chandrasegaran, Srinivasan

Zinc finger nucleases (ZFNs) are custom-designed molecular scissors, engineered to cut at specific DNA sequences. ZFNs combine the zinc finger proteins (ZFPs) with the nonspecific cleavage domain of the FokI restriction enzyme. The DNA-binding specificity of ZFNs can be easily altered experimentally. This easy manipulation of the ZFN recognition specificity enables one to deliver a targeted double-strand break (DSB) to a genome. The targeted DSB stimulates local gene targeting by several orders of magnitude at that specific cut site via homologous recombination (HR). Thus, ZFNs have become an important experimental tool to make site-specific and permanent alterations to genomes of not only plants and mammals but also of many other organisms. Engineering of custom ZFNs involves many steps. The first step is to identify a ZFN site at or near the chosen chromosomal target within the genome to which ZFNs will bind and cut. The second step is to design and/or select various ZFP combinations that will bind to the chosen target site with high specificity and affinity. The DNA coding sequence for the designed ZFPs are then assembled by polymerase chain reaction (PCR) using oligonucleotides. The third step is to fuse the ZFP constructs to the FokI cleavage domain. The ZFNs are then expressed as proteins by using the rabbit reticulocyte in vitro transcription/translation system and the protein products assayed for their DNA cleavage specificity.

Anharmonic, dynamic and functional level effects in far-infrared spectroscopy: Phenol derivatives

NASA Astrophysics Data System (ADS)

Bakker, Daniël J.; Ong, Qin; Dey, Arghya; Mahé, Jérôme; Gaigeot, Marie-Pierre; Rijs, Anouk M.

2017-12-01

The far-infrared (far-IR) spectra of phenol and four ortho-substituted phenol derivatives, including three deuterated analogs, are presented. These spectra, measured using the free electron laser FELIX, are used to compare the performance of Born-Oppenheimer Molecular Dynamics (BOMD) with several commonly used levels of static density functional theory in the far-IR region. The molecules studied here form intramolecular hydrogen bonds of different strengths (except phenol), display diverse degrees of flexibility, and the OH moieties of the molecules provide large amplitude, anharmonic OH torsional modes. Since several of the molecules contain two OH groups, strong anharmonic couplings can also be present. Moreover, the experimental far-IR spectra of phenol and saligenin show overtones and combination bands as proven by the measurements of their deuterated analogs. All these characteristics of the molecules enable us to test the performance of the applied levels of theory on different complicating factors. Briefly summarized, both the strength of the hydrogen bond and molecular rigidity do not significantly influence the agreement between theory and experiment. All applied theoretical methods have difficulties to consistently predict modes that include the anharmonic OH torsional motion, resulting in overestimated intensities and frequencies. Coupling between two OH functional groups provides an additional challenge for theories, as seen for catechol. The various employed theoretical methods are found to complement each other, showing good results for complex harmonic modes in the case of static B3LYP-D3, while improved results are observed for anharmonic modes, including the OH torsional modes and their couplings, in the case of BOMD. Additionally, BOMD calculates the relative intensities better than the other theories. VPT2 reproduces weak anharmonic modes well, but it overestimates shifts and intensities for strong anharmonic modes.

Experimental strength of restorations with fibre posts at different stages, with and without using a simulated ligament.

PubMed

Pérez-González, A; González-Lluch, C; Sancho-Bru, J L; Rodríguez-Cervantes, P J; Barjau-Escribano, A; Forner-Navarro, L

2012-03-01

The aim of this study was to analyse the strength and failure mode of teeth restored with fibre posts under retention and flexural-compressive loads at different stages of the restoration and to analyse whether including a simulated ligament in the experimental setup has any effect on the strength or the failure mode. Thirty human maxillary central incisors were distributed in three different groups to be restored with simulation of different restoration stages (1: only post, 2: post and core, 3: post-core and crown), using Rebilda fibre posts. The specimens were inserted in resin blocks and loaded by means of a universal testing machine until failure under tension (stage 1) and 50º flexion (stages 2-3). Half the specimens in each group were restored using a simulated ligament between root dentine and resin block and the other half did not use this element. Failure in stage 1 always occurred at the post-dentine interface, with a mean failure load of 191·2 N. Failure in stage 2 was located mainly in the core or coronal dentine (mean failure load of 505·9 N). Failure in stage 3 was observed in the coronal dentine (mean failure load 397·4 N). Failure loads registered were greater than expected masticatory loads. Fracture modes were mostly reparable, thus indicating that this post is clinically valid at the different stages of restoration studied. The inclusion of the simulated ligament in the experimental system did not show a statistically significant effect on the failure load or the failure mode. © 2011 Blackwell Publishing Ltd.

Microstructure and Mechanical Properties of Dissimilar Friction Stir Spot Welding Between St37 Steel and 304 Stainless Steel

NASA Astrophysics Data System (ADS)

Khodadadi, Ali; Shamanian, Morteza; Karimzadeh, Fathallah

2017-05-01

In the present study, St37 low-carbon steel and 304 stainless steel were welded successfully, with the thickness of 2 mm, by a friction stir spot welding process carried out at the tool dwell time of 6 s and two different tool rotational speeds of 630 and 1250 rpm. Metallographic examinations revealed four different zones including SZ and HAZ areas of St37 steel and SZ and TMAZ regions of 304 stainless steel in the weld nugget, except the base metals. X-ray diffraction and energy-dispersive x-ray spectroscopy experiments were used to investigate the possible formation of such phases as chromium carbide. Based on these experiments, no chromium carbide precipitation was found. The recrystallization of the weld nugget in the 304 steel and the phase transformations of the weld regions in the St37 steel enhanced the hardness of the weld joint. Hardness changes of joint were acceptable and approximately uniform, as compared to the resistance spot weld. In this research, it was also observed that the tensile/shear strength, as a crucial factor, was increased with the rise in the tool rotational speed. The bond length along the interface between metals, as an effective parameter to increase the tensile/shear strength, was also determined. At higher tool rotational speeds, the bond length was found to be improved, resulting in the tensile/shear strength of 6682 N. Finally, two fracture modes were specified through the fracture mode analysis of samples obtained from the tensile/shear test consisting of the shear fracture mode and the mixed shear/tensile fracture mode.

Helicon normal modes in Proto-MPEX

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

Piotrowicz, Pawel A.; Caneses, Juan F.; Green, David L.

Here, the Proto-MPEX helicon source has been operating in a high electron density 'helicon-mode'. Establishing plasma densities and magnetic field strengths under the antenna that allow for the formation of normal modes of the fast-wave are believed to be responsible for the 'helicon-mode'. A 2D finite-element full-wave model of the helicon antenna on Proto-MPEX is used to identify the fast-wave normal modes responsible for the steady-state electron density profile produced by the source. We also show through the simulation that in the regions of operation in which core power deposition is maximum the slow-wave does not deposit significant power besidesmore » directly under the antenna. In the case of a simulation where a normal mode is not excited significant edge power is deposited in the mirror region.« less

Helicon normal modes in Proto-MPEX

DOE PAGES

Piotrowicz, Pawel A.; Caneses, Juan F.; Green, David L.; ...

2018-05-22

Here, the Proto-MPEX helicon source has been operating in a high electron density 'helicon-mode'. Establishing plasma densities and magnetic field strengths under the antenna that allow for the formation of normal modes of the fast-wave are believed to be responsible for the 'helicon-mode'. A 2D finite-element full-wave model of the helicon antenna on Proto-MPEX is used to identify the fast-wave normal modes responsible for the steady-state electron density profile produced by the source. We also show through the simulation that in the regions of operation in which core power deposition is maximum the slow-wave does not deposit significant power besidesmore » directly under the antenna. In the case of a simulation where a normal mode is not excited significant edge power is deposited in the mirror region.« less

Gaussian discriminating strength

NASA Astrophysics Data System (ADS)

Rigovacca, L.; Farace, A.; De Pasquale, A.; Giovannetti, V.

2015-10-01

We present a quantifier of nonclassical correlations for bipartite, multimode Gaussian states. It is derived from the Discriminating Strength measure, introduced for finite dimensional systems in Farace et al., [New J. Phys. 16, 073010 (2014), 10.1088/1367-2630/16/7/073010]. As the latter the new measure exploits the quantum Chernoff bound to gauge the susceptibility of the composite system with respect to local perturbations induced by unitary gates extracted from a suitable set of allowed transformations (the latter being identified by posing some general requirements). Closed expressions are provided for the case of two-mode Gaussian states obtained by squeezing or by linearly mixing via a beam splitter a factorized two-mode thermal state. For these density matrices, we study how nonclassical correlations are related with the entanglement present in the system and with its total photon number.

Hydrogen Assisted Cracking of High Strength Steel Welds

DTIC Science & Technology

1988-05-01

cracking of high strength steel welds. The microplasticity theory originally proposed by M Beachem is used to explain the effect of hydrogen on the var... microplasticity mechanism rather than embrittlement (B7). He suggests that the hydrogen in the lattice ahead of the crack tip assists whatever...intensity level on the observed fracture mode. This theory postu- lates that hydrogen will promote cracking by a microplasticity mechanism rather than

Evidence for the Presence of Hn-PAHs in Post AGB Stars

NASA Technical Reports Server (NTRS)

Materese, Christopher K.; Bregman, Jesse D.; Sandford, Scott A.

2017-01-01

Polycyclic aromatic hydrocarbons (PAHs) are believed to be ubiquitous in space therefore represent an important class of molecules for the field of astrochemistry. PAHs are relatively stable under interstellar conditions, account for a significant fraction of the known Universe's molecular carbon inventory, and are believed responsible for numerous telltale interstellar infrared emission bands. PAHs can be subdivided into numerous classes, one of which is Hydrogenated PAHs (Hn-PAHs). Hn-PAHs are multi-ringed partially aromatic compounds with excess hydrogenation, leading to a partial disruption of the aromatic system. The infrared spectra of these compounds produce telltale signatures that make them distinct from ordinary aromatic or aliphatic molecules (or a mixture of both). Hn-PAHs may be an important subclass of PAHs that could explain the spectra of some astronomical objects with anomalously large 3.4 micron features. The 3.4 micron feature observed in these objects may be associated with the aliphatic C-H stretching vibrations of the excess hydrogen. If this presumption is correct, we also expect to observe methylene scissoring modes at 6.9 microns. We have recently conducted a series of follow-up observations to compliment our laboratory experiments into the properties of Hn-PAHs. Here we present our laboratory and observational results in support of the hypothesis that Hn-PAHs are a viable candidate molecule as the emission source for numerous post-asymptotic giant branch objects with abnormally large 3.4 micron features.

Nanomechanical modeling of interfaces of polyvinyl alcohol (PVA)/clay nanocomposite

NASA Astrophysics Data System (ADS)

Paliwal, Bhasker; Lawrimore, William B.; Chandler, Mei Q.; Horstemeyer, Mark F.

2017-05-01

We study interfacial debonding of several representative structures of polyvinyl alcohol (PVA)/pyrophillite-clay systems - both gallery-interface (polymer/clay interface in the interlayer region containing polymer between clay layers stacked parallel to each other) and matrix-interphase (polymer/clay interphase-region when individual clay layers are well separated and dispersed in the polymer matrix) - using molecular dynamics simulations, while explicitly accounting for shearing/sliding (i.e. Mode-II) deformation mode. Ten nanocomposite geometries (five 2-D periodic structures for tension and five 1-D periodic structures for shearing) were constructed to quantify the structure-property relations by varying the number density of polymer chains, length of polymer chains and model dimensions related to the interface deformation. The results were subsequently mapped into a cohesive traction-separation law, including evaluation of peak traction and work of separation that are used to characterise the interface load transfer for larger length scale micromechanical models. Results suggest that under a crack nucleation opening mode (i.e. Mode-I), the matrix-interphase exhibits noticeably greater strength and a greater work of separation compared to the gallery-interface; however, they were similar under the shearing/sliding mode of deformation. When compared to shearing/sliding, the tensile peak opening mode stresses were considerably greater but the displacement at the peak stress, the displacement at the final failure and the work of separation were considerably lower. Results also suggest that PVA/clay nanocomposites with higher degree of exfoliation compared with nanocomposites with higher clay-intercalation can potentially display higher strength under tension-dominated loading for a given clay volume fraction.

Avalanche weak layer shear fracture parameters from the cohesive crack model

NASA Astrophysics Data System (ADS)

McClung, David

2014-05-01

Dry slab avalanches release by mode II shear fracture within thin weak layers under cohesive snow slabs. The important fracture parameters include: nominal shear strength, mode II fracture toughness and mode II fracture energy. Alpine snow is not an elastic material unless the rate of deformation is very high. For natural avalanche release, it would not be possible that the fracture parameters can be considered as from classical fracture mechanics from an elastic framework. The strong rate dependence of alpine snow implies that it is a quasi-brittle material (Bažant et al., 2003) with an important size effect on nominal shear strength. Further, the rate of deformation for release of an avalanche is unknown, so it is not possible to calculate the fracture parameters for avalanche release from any model which requires the effective elastic modulus. The cohesive crack model does not require the modulus to be known to estimate the fracture energy. In this paper, the cohesive crack model was used to calculate the mode II fracture energy as a function of a brittleness number and nominal shear strength values calculated from slab avalanche fracture line data (60 with natural triggers; 191 with a mix of triggers). The brittleness number models the ratio of the approximate peak value of shear strength to nominal shear strength. A high brittleness number (> 10) represents large size relative to fracture process zone (FPZ) size and the implications of LEFM (Linear Elastic Fracture Mechanics). A low brittleness number (e.g. 0.1) represents small sample size and primarily plastic response. An intermediate value (e.g. 5) implies non-linear fracture mechanics with intermediate relative size. The calculations also implied effective values for the modulus and the critical shear fracture toughness as functions of the brittleness number. The results showed that the effective mode II fracture energy may vary by two orders of magnitude for alpine snow with median values ranging from 0.08 N/m (non-linear) to 0.18 N/m (LEFM) for median slab density around 200 kg/m3. Schulson and Duval (2009) estimated the fracture energy of solid ice (mode I) to be about 0.22-1 N/m which yields rough theoretical limits of about 0.05- 0.2 N/m for density 200 kg/m3 when the ice volume fraction is accounted for. Mode I results from lab tests (Sigrist, 2006) gave 0.1 N/m (200 kg/m3). The median effective mode II shear fracture toughness was calculated between 0.31 to 0.35 kPa(m)1/2 for the avalanche data. All the fracture energy results are much lower than previously calculated from propagation saw tests (PST) results for a weak layer collapse model (1.3 N/m) (Schweizer et al., 2011). The differences are related to model assumptions and estimates of the effective slab modulus. The calculations in this paper apply to quasi-static deformation and mode II weak layer fracture whereas the weak layer collapse model is more appropriate for dynamic conditions which follow fracture initiation (McClung and Borstad, 2012). References: Bažant, Z.P. et al. (2003) Size effect law and fracture mechanics of the triggering of dry snow slab avalanches, J. Geophys. Res. 108(B2): 2119, doi:10.1029/2002JB))1884.2003. McClung, D.M. and C.P. Borstad (2012) Deformation and energy of dry snow slabs prior to fracture propagation, J. Glaciol. 58(209), 2012 doi:10.3189/2012JoG11J009. Schulson, E.M and P. Duval (2009) Creep and fracture of ice, Cambridge University Press, 401 pp. Schweizer, J. et al. (2011) Measurements of weak layer fracture energy, Cold Reg. Sci. and Tech. 69: 139-144. Sigrist, C. (2006) Measurement of fracture mechanical properties of snow and application to dry snow slab avalanche release, Ph.D thesis: 16736, ETH, Zuerich: 139 pp.

Prediction of Composite Laminate Strength Properties Using a Refined Zigzag Plate Element

NASA Technical Reports Server (NTRS)

Barut, Atila; Madenci, Erdogan; Tessler, Alexander

2013-01-01

This study presents an approach that uses the refined zigzag element, RZE(exp2,2) in conjunction with progressive failure criteria to predict the ultimate strength of composite laminates based on only ply-level strength properties. The methodology involves four major steps: (1) Determination of accurate stress and strain fields under complex loading conditions using RZE(exp2,2)-based finite element analysis, (2) Determination of failure locations and failure modes using the commonly accepted Hashin's failure criteria, (3) Recursive degradation of the material stiffness, and (4) Non-linear incremental finite element analysis to obtain stress redistribution until global failure. The validity of this approach is established by considering the published test data and predictions for (1) strength of laminates under various off-axis loading, (2) strength of laminates with a hole under compression, and (3) strength of laminates with a hole under tension.

On the strength of random fiber networks

NASA Astrophysics Data System (ADS)

Deogekar, S.; Picu, R. C.

2018-07-01

Damage accumulation and failure in random fiber networks is of importance in a variety of applications, from design of synthetic materials, such as paper and non-wovens, to accidental tearing of biological tissues. In this work we study these processes using three-dimensional models of athermal fiber networks, focusing attention on the modes of failure and on the relationship between network strength and network structural parameters. We consider network failure at small and large strains associated with the rupture of inter-fiber bonds. It is observed that the strength increases linearly with the network volume fraction and with the bond strength, while the stretch at peak stress is inversely related to these two parameters. A small fraction of the bonds rupture before peak stress and this fraction increases with increasing failure stretch. Rendering the bond strength stochastic causes a reduction of the network strength. However, heterogeneity retards damage localization and increases the stretch at peak stress, therefore promoting ductility.

[The effect of core veneer thickness ratio on the flexural strength of diatomite-based dental ceramic].

PubMed

Jiang, Jie; Zhang, Xin; Gao, Mei-qin; Zhang, Fei-min; Lu, Xiao-li

2015-06-01

To evaluate the effect of different core veneer thickness ratios on the flexural strength and failure mode of bilayered diatomite-based dental ceramics. Diatomite-based dental ceramics blocks (16 mm×5.4 mm×1 mm) were sintered with different thickness of veneer porcelains: 0 mm (group A), 0.6 mm (group B), 0.8 mm (group C) and 1.0 mm (group D). Flexural strength was detected and scanning electron microscope was used to observe the interface microstructure. Statistical analysis was performed using SPSS 17.0 software package. With the increase of the thickness of the veneer porcelain, flexural strength of group C showed highest flexural strength up to (277.24±5.47) MPa. Different core veneer thickness ratios can significantly influence the flexural strength of bilayered diatomite-based dental ceramics. Supported by Science and Technology Projects of Nantong City (HS2013010).

Laboratory determination of the infrared band strengths of pyrene frozen in water ice: Implications for the composition of interstellar ices

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

Hardegree-Ullman, E. E.; Gudipati, M. S.; Werner, M.

2014-04-01

Broad infrared emission features (e.g., at 3.3, 6.2, 7.7, 8.6, and 11.3 μm) from the gas phase interstellar medium have long been attributed to polycyclic aromatic hydrocarbons (PAHs). A significant portion (10%-20%) of the Milky Way's carbon reservoir is locked in PAH molecules, which makes their characterization integral to our understanding of astrochemistry. In molecular clouds and the dense envelopes and disks of young stellar objects (YSOs), PAHs are expected to be frozen in the icy mantles of dust grains where they should reveal themselves through infrared absorption. To facilitate the search for frozen interstellar PAHs, laboratory experiments were conductedmore » to determine the positions and strengths of the bands of pyrene mixed with H{sub 2}O and D{sub 2}O ices. The D{sub 2}O mixtures are used to measure pyrene bands that are masked by the strong bands of H{sub 2}O, leading to the first laboratory determination of the band strength for the CH stretching mode of pyrene in water ice near 3.25 μm. Our infrared band strengths were normalized to experimentally determined ultraviolet band strengths, and we find that they are generally ∼50% larger than those reported by Bouwman et al. based on theoretical strengths. These improved band strengths were used to reexamine YSO spectra published by Boogert et al. to estimate the contribution of frozen PAHs to absorption in the 5-8 μm spectral region, taking into account the strength of the 3.25 μm CH stretching mode. It is found that frozen neutral PAHs contain 5%-9% of the cosmic carbon budget and account for 2%-9% of the unidentified absorption in the 5-8 μm region.« less

Casein phosphopeptide-amorphous calcium phosphate and shear bond strength of adhesives to primary teeth enamel.

PubMed

Farokh Gisovar, Elham; Hedayati, Nassim; Shadman, Niloofar; Shafiee, Leila

2015-02-01

CPP-ACP (Phosphopeptide-Amorphous Calcium Phosphate) has an important role in caries prevention in pediatric patients. This study was done, because of the great use of CPP-ACP and the need for restoration for teeth treated with CPP-ACP as well as the importance of shear bond strength of adhesives in the success of restorations. This study aimed to evaluate the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on shear bond strength of dental adhesives to enamel of primary teeth molars. This in vitro study was conducted on 180 extracted primary molars. They were randomly divided into 6 groups and each group was divided into 2 subgroups (treated with CPP-ACP and untreated). In subgroups with CPP-ACP, enamel was treated with CPP-ACP paste 1 h/d for 5 days. Types of adhesives that were evaluated in this study were Tetric N-Bond, AdheSE, AdheSE One F, single Bond 2, SE Bond, and Adper Prompt L-Pop. Shear bond strength was tested with a universal testing machine and mode of failure was evaluated under stereomicroscope. Data were analyzed by T test, 2-way analysis of variance (ANOVA), Tukey and Fisher exact test using SPSS18. P < 0.05 was considered as significance level. Shear bond strengths of different adhesive systems to enamel of primary teeth treated and untreated with CPP-ACP showed no significant difference (P > 0.05). Mode of failure in all groups regardless of CPP-ACP administration was mainly adhesive type. Our results indicated that CPP-ACP did not affect shear bond strength of studied adhesives to primary teeth enamel. To have a successful and durable composite restoration, having a high strength bonding is essential. Considering the wide use of CPP-ACP in preventing tooth decay and the role of adhesive shear bond strength (SBS) in success of composite restoration, we conducted the present study to evaluate the effect of CPP-ACP on the SBS of adhesives to primary teeth enamel.