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Sample records for bec-bcs crossover experiments

  1. BCS wave-function approach to the BEC-BCS crossover of exciton-polariton condensates.

    PubMed

    Byrnes, Tim; Horikiri, Tomoyuki; Ishida, Natsuko; Yamamoto, Yoshihisa

    2010-10-29

    The crossover between low and high density regimes of exciton-polariton condensates is examined using a BCS wave-function approach. Our approach is an extension of the BEC-BCS crossover theory for excitons, but includes a cavity photon field. The approach can describe both the low density limit, where the system can be described as a Bose-Einstein condensate (BEC) of exciton-polaritons, and the high density limit, where the system enters a photon-dominated regime. In contrast to the exciton BEC-BCS crossover where the system approaches an electron-hole plasma, the polariton high density limit has strongly correlated electron-hole pairs. At intermediate densities, there is a regime with BCS-like properties, with a peak at nonzero momentum of the singlet pair function. We calculate the expected photoluminescence and give several experimental signatures of the crossover.

  2. Motion of a solitonic vortex in the BEC-BCS crossover.

    PubMed

    Ku, Mark J H; Ji, Wenjie; Mukherjee, Biswaroop; Guardado-Sanchez, Elmer; Cheuk, Lawrence W; Yefsah, Tarik; Zwierlein, Martin W

    2014-08-08

    We observe a long-lived solitary wave in a superfluid Fermi gas of (6)Li atoms after phase imprinting. Tomographic imaging reveals the excitation to be a solitonic vortex, oriented transverse to the long axis of the cigar-shaped atom cloud. The precessional motion of the vortex is directly observed, and its period is measured as a function of the chemical potential in the BEC-BCS crossover. The long period and the correspondingly large ratio of the inertial to the bare mass of the vortex are in good agreement with estimates based on superfluid hydrodynamics that we derive here using the known equation of state in the BEC-BCS crossover.

  3. Topological superfluids and the BEC-BCS crossover in the attractive Haldane-Hubbard model

    NASA Astrophysics Data System (ADS)

    Zhang, Yi-Cai; Xu, Zhihao; Zhang, Shizhong

    2017-04-01

    Motivated by the recent realization of the Haldane model in a shaking optical lattice, we investigate the effects of attractive interaction and the BEC-BCS crossover in this model at and away from half-filling. We show that, contrary to the usual s -wave BEC-BCS crossover in the lattice, a topological superfluid with Chern number C =2 appears in an extended region of the phase space for intermediate strength of the attractive interaction on the interaction-density plane. When inversion symmetry is broken, a gapless weak topological state is realized. We also investigate the fluctuations in these superfluid phases and show that the Anderson-Bogoliubov mode is quadratic due to time-reversal symmetry breaking and the existence of an undamped Leggett mode in the strong-coupling limit. Near the topological phase transition, the damping of the Leggett mode reaches its maximum.

  4. BEC-BCS crossover driven by the axial anomaly in the NJL model

    NASA Astrophysics Data System (ADS)

    Abuki, Hiroaki; Baym, Gordon; Hatsuda, Tetsuo; Yamamoto, Naoki

    2010-12-01

    We study the QCD phase structure in the three-flavor Nambu-Jona-Lasinio model, incorporating the chiral-diquark interplay due to the axial anomaly. We demonstrate that for a certain range of model parameters, the low temperature critical point predicted by a Ginzburg-Landau analysis appears in the phase diagram. In addition, we show that the axial anomaly presents a new scenario for a possible BEC-BCS crossover in the color-flavor locked phase of QCD.

  5. Critical Temperature Curve in BEC-BCS Crossover

    SciTech Connect

    Burovski, Evgeni; Kozik, Evgeny |; Prokofev, Nikolay ||; Svistunov, Boris |; Troyer, Matthias

    2008-08-29

    The strongly correlated regime of the crossover from Bardeen-Cooper-Schrieffer pairing to Bose-Einstein condensation can be realized by diluting a system of two-component fermions with a short-range attractive interaction. We investigate this system via a novel continuous-space-time diagrammatic determinant Monte Carlo method and determine the universal curve T{sub c}/{epsilon}{sub F} for the transition temperature between the normal and the superfluid states as a function of the scattering length with the maximum on the Bose-Einstein condensation side. At unitarity, we confirm that T{sub c}/{epsilon}{sub F}=0.152(7)

  6. Ginzburg-Landau theory of a trapped Fermi gas with a BEC-BCS crossover

    SciTech Connect

    Huang Kun; Yu Zengqiang; Yin Lan

    2009-05-15

    The Ginzburg-Landau theory of a trapped Fermi gas with a BEC-BCS crossover is derived by the path-integral method. In addition to the standard Ginzburg-Landau equation, a second equation describing the total atom density is obtained. These two coupled equations are necessary to describe both homogeneous and inhomogeneous systems. The Ginzburg-Landau theory is valid near the transition temperature T{sub c} on both sides of the crossover. In the weakly interacting BEC region, it is also accurate at zero temperature where the Ginzburg-Landau equation can be mapped onto the Gross-Pitaevskii (GP) equation. The applicability of GP equation at finite temperature is discussed. On the BEC side, the fluctuation of the order parameter is studied and the renormalization to the molecule coupling constant is obtained.

  7. Collective mode of homogeneous superfluid Fermi gases in the BEC-BCS crossover

    SciTech Connect

    Combescot, R.; Kagan, M. Yu.; Stringari, S.

    2006-10-15

    We perform a detailed study of the collective mode across the whole crossover from the Bose-Einstein condensate (BEC)-to the BCS regime in fermionic gases at zero temperature, covering the whole range of energy beyond the linear regime. This is done on the basis of the dynamical BCS model. We recover first the results of the linear regime in a simple form. Then specific attention is paid to the nonlinear part of the dispersion relation and its interplay with the continuum of single-fermionic excitations. In particular we consider in detail the merging of the collective mode into the continuum of single-fermionic excitations. This occurs not only on the BCS side of the crossover, but also slightly beyond unitarity on the BEC side. Another remarkable feature is the very linear behavior of the dispersion relation in the vicinity of unitarity almost up to merging with the continuum. Finally, while on the BEC side the mode is quite analogous to the Bogoliubov mode, a difference appears at high wave vectors. On the basis of our results we determine the Landau critical velocity in the BEC-BCS crossover which is found to be largest close to unitarity. Our investigation has revealed interesting qualitative features which deserve experimental exploration as well as further theoretical studies by more sophisticated means.

  8. Theoretical studies of carbon nanotube superconductivity and the BEC-BCS crossover

    NASA Astrophysics Data System (ADS)

    Sun, Mingyuan

    This thesis contains two parts. The first part is about superconductivity in 4-Angstrom carbon nanotubes (CNTs) embedded in linear, parallel pores of AFI zeolite crystals. In the second part, we study the pseudogap problem in the BEC-BCS crossover. The 4-Angstrom CNTs can be formed in the linear pores of AFI zeolite crystals. They exhibit quasi one-dimensional (1D) fluctuation superconductivity below a temperature of about 15 K. In samples with improved quality, three-dimensional (3D) superconducting behaviors were observed, which display a sharp resistance drop around the temperature 7.5 K. We build a simple model to explain this 1D-3D crossover. The system is inhomogeneous, and contains randomly situated bundles of small CNTs. We use the Ginzburg-Landau (GL) model, with weak Josephson-coupling between the bundles, to model the system. Monte Carlo (MC) simulations are employed to study the superconducting behaviors of this model. Owing to the weak Josephson-coupling, there exists a phase transition at a temperature around 7.5 K, which displays the signatures of the Berezinskii- Kosterlitz-Thouless (BKT) transition. Below this critical temperature, the phase fluctuations along the c-axis of the bundles are suppressed, and the whole system gradually approaches complete coherence as the temperature is lowered. This behavior is denoted a 1D to 3D crossover superconducting transition. The weak Josephson-coupling does not significantly contribute to the free energy of the system, thus the specific heat still exhibits quasi 1D characteristics, with a rounded peak between 7.5 K and 15 K. The results of numerical simulations are in good agreement with the experimental observations. The BEC-BCS crossover has been studied for decades. It is still controversial about whether there exists a pseudogap state above the critical temperature around the unitary limit, where Cooper pairs exist but do not condense. In this thesis, we study the Fermi gas with contact interaction at

  9. Snake instability of dark solitons across the BEC-BCS crossover: An effective-field-theory perspective

    NASA Astrophysics Data System (ADS)

    Lombardi, G.; Van Alphen, W.; Klimin, S. N.; Tempere, J.

    2017-09-01

    In the present article the snake instability mechanism for dark solitons in superfluid Fermi gases is studied in the context of a recently developed effective field theory [S. N. Klimin et al., Eur. Phys. J. B 88, 122 (2015), 10.1140/epjb/e2015-60213-4]. This theoretical treatment has proven to be suitable to study stable dark solitons in quasi-one-dimensional setups across the BEC-BCS crossover. In this paper the nodal plane of the stable soliton solution is perturbed by adding a transverse modulation. The numerical solution of the system of coupled nonlinear differential equations describing the amplitude of the perturbation leads to an estimate of the growth rate and characteristic length scale of the instability, which are calculated for a wide range of interaction regimes and compared to other theoretical predictions. The behavior of the maximum transverse size that the atomic cloud can have in order to preserve the stability is described across the BEC-BCS crossover. The analysis of the effects of spin imbalance on this critical length reveals a stabilization of the soliton with increasing imbalance and therefore provides the experimental community with a method to achieve the realization of stable solitons in real three-dimensional configurations, without reducing the system dimensionality.

  10. Equation of State of Ultracold Fermions in the 2D BEC-BCS Crossover Region.

    PubMed

    Boettcher, I; Bayha, L; Kedar, D; Murthy, P A; Neidig, M; Ries, M G; Wenz, A N; Zürn, G; Jochim, S; Enss, T

    2016-01-29

    We report the experimental measurement of the equation of state of a two-dimensional Fermi gas with attractive s-wave interactions throughout the crossover from a weakly coupled Fermi gas to a Bose gas of tightly bound dimers as the interaction strength is varied. We demonstrate that interactions lead to a renormalization of the density of the Fermi gas by several orders of magnitude. We compare our data near the ground state and at finite temperature with predictions for both fermions and bosons from quantum Monte Carlo simulations and Luttinger-Ward theory. Our results serve as input for investigations of close-to-equilibrium dynamics and transport in the two-dimensional system.

  11. Optimized perturbation theory applied to the study of the thermodynamics and BEC-BCS crossover in the three-color Nambu-Jona-Lasinio model

    NASA Astrophysics Data System (ADS)

    Duarte, Dyana C.; Farias, R. L. S.; Manso, Pedro H. A.; Ramos, Rudnei O.

    2017-09-01

    The Nambu-Jona-Lasinio model with two flavors, three colors, and diquark interactions is analyzed in the context of optimized perturbation theory (OPT). Corrections to the thermodynamical potential that go beyond the large-Nc (LN) approximation are taken into account, and the region of the phase diagram corresponding to intermediate chemical potentials and very low temperatures is explored. The simultaneous presence of both the quark-antiquark and diquark condensates can cause the system to behave as a fluid composed of a Bose-Einstein condensate (BEC) or a color superconductor one, in the form of a Bardeen-Cooper-Schrieffer (BCS) superfluid. The BEC-BCS crossover is then studied in the nonperturbative OPT scheme. The results obtained in the context of the OPT method are then contrasted with those obtained in the LN approximation. We show that there are values for the coupling constants related to quark-quark and quark-antiquark interactions where the corrections beyond LN brought by the OPT method can influence the behavior of the diquark condensate and the effective quark mass as a function of the baryon chemical potential. These changes in the behavior of the phase structure of the model modify the location of the critical point related to the phase structure as a whole of the model. Also, when we impose the color neutrality condition, our results show that the nature of the phase transition can change as well, shifting the ratio of the quark-antiquark and quark-quark interactions to higher values in the OPT case as compared to the LN approximation.

  12. Self-consistent theory for molecular instabilities in a normal degenerate Fermi gas in the BEC-BCS crossover

    SciTech Connect

    Combescot, R.; Leyronas, X.; Kagan, M. Yu.

    2006-02-15

    We investigate within a self-consistent theory the molecular instabilities arising in the normal state of a homogeneous degenerate Fermi gas, covering the whole Bose-Einstein condensate (BEC) to BCS crossover. These are the standard instability for molecular formation, the BCS instability which corresponds to the formation of Cooper pairs, and the related Bose-Einstein instability. These instabilities manifest themselves in the properties of the particle-particle vertex, which we calculate in a ladder approximation. To find the critical temperatures corresponding to these various instabilities, we handle the properties of the interacting Fermi gas on the same footing as the instabilities by making use of the same vertex. This approximate treatment is shown to be quite satisfactory in a number of limiting situations where it agrees with known exact results. The results for the BCS critical temperature and for the BE condensation are found to be in fair agreement with earlier results. The threshold for formation of molecules at rest undergoes a sizable shift toward the BEC side, due to quantum effects arising from the presence of the degenerate Fermi gas. This should make its experimental observation fairly easy. This shift remains important at least up to temperatures comparable to the Fermi energy of the gas.

  13. Excitonic Condensation under Spin-Orbit Coupling and BEC-BCS Crossover

    NASA Astrophysics Data System (ADS)

    Hakioǧlu, T.; Şahin, Mehmet

    2007-04-01

    The condensation of electron-hole pairs is studied at zero temperature and in the presence of a weak spin-orbit coupling (SOC) in coupled quantum wells. Under realistic conditions, a perturbative SOC can have observable effects in the order parameter of the condensate. First, the fermion exchange symmetry is absent. As a result, the condensate spin has no definite parity. Additionally, the excitonic SOC breaks the rotational symmetry yielding a complex order parameter in an unconventional way; i.e., the phase pattern of the order parameter is a function of the condensate density. This is manifested through finite off-diagonal components of the static spin susceptibility, suggesting a new experimental method to confirm an excitonic condensate.

  14. Critical behavior in one dimension: Unconventional pairing, phase separation, BEC-BCS crossover, and magnetic Lifshitz transition

    NASA Astrophysics Data System (ADS)

    Ptok, Andrzej; Cichy, Agnieszka; Rodríguez, Karen; Kapcia, Konrad Jerzy

    2017-03-01

    We study the superconducting properties of population-imbalanced ultracold Fermi mixtures in one-dimensional optical lattices that can be effectively described by the spin-imbalanced attractive Hubbard model in the presence of a Zeeman magnetic field. We use the mean-field theory approach to obtain the ground-state phase diagrams including some unconventional superconducting phases such as the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase, and the η phase (an extremal case of the FFLO phase), both for the case of a fixed chemical potential and for a fixed number of particles. It allows us to determine optimal regimes for the FFLO phase as well as η -pairing stability. We also investigate the evolution from the weak coupling (BCS-like limit) to the strong coupling limit of tightly bound local pairs (BEC) with increasing attraction, at T =0 . Finally, the obtained results show that in spite of the occurrence of the Lifshitz transition induced by an external magnetic field, the superconducting state can still exist in the system, at higher magnetic field values.

  15. Influence analysis on crossover design experiment in bioequivalence studies.

    PubMed

    Huang, Yufen; Ke, Bo-Shiang

    2014-01-01

    Crossover designs are commonly used in bioequivalence studies. However, the results can be affected by some outlying observations, which may lead to the wrong decision on bioequivalence. Therefore, it is essential to investigate the influence of aberrant observations. Chow and Tse in 1990 discussed this issue by considering the methods based on the likelihood distance and estimates distance. Perturbation theory provides a useful tool for the sensitivity analysis on statistical models. Hence, in this paper, we develop the influence functions via the perturbation scheme proposed by Hampel as an alternative approach on the influence analysis for a crossover design experiment. Moreover, the comparisons between the proposed approach and the method proposed by Chow and Tse are investigated. Two real data examples are provided to illustrate the results of these approaches. Our proposed influence functions show excellent performance on the identification of outlier/influential observations and are suitable for use with small sample size crossover designs commonly used in bioequivalence studies.

  16. Crossover from capillary fingering to viscous fingering for immiscible unstable flow:Experiment and modeling

    NASA Astrophysics Data System (ADS)

    Ferer, M.; Ji, Chuang; Bromhal, Grant S.; Cook, Joshua; Ahmadi, Goodarz; Smith, Duane H.

    2004-07-01

    Invasion percolation with trapping (IPT) and diffusion-limited aggregation (DLA) are simple fractal models, which are known to describe two-phase flow in porous media at well defined, but unphysical limits of the fluid properties and flow conditions. A decade ago, Fernandez, Rangel, and Rivero predicted a crossover from IPT (capillary fingering) to DLA (viscous fingering) for the injection of a zero-viscosity fluid as the injection velocity was increased from zero. [J. F. Fernandez, R. Rangel, and J. Rivero, Phys. Rev. Lett. 67, 2958 (1991)]. We have performed experiments in which air is injected into a glass micromodel to displace water. These experiments clearly demonstrate this crossover as the injection velocity of the air is increased. Furthermore, simulations, using our standard pore-level model, also support the predicted IPT-to-DLA crossover, as well as the predicted power-law behavior of the characteristic crossover length.

  17. The Widom line and dynamical crossover in supercritical water: Popular water models versus experiments

    SciTech Connect

    Corradini, D.; Rovere, M.; Gallo, P.

    2015-09-21

    In a previous study [Gallo et al., Nat. Commun. 5, 5806 (2014)], we have shown an important connection between thermodynamic and dynamical properties of water in the supercritical region. In particular, by analyzing the experimental viscosity and the diffusion coefficient obtained in simulations performed using the TIP4P/2005 model, we have found that the line of response function maxima in the one phase region, the Widom line, is connected to a crossover from a liquid-like to a gas-like behavior of the transport coefficients. This is in agreement with recent experiments concerning the dynamics of supercritical simple fluids. We here show how different popular water models (TIP4P/2005, TIP4P, SPC/E, TIP5P, and TIP3P) perform in reproducing thermodynamic and dynamic experimental properties in the supercritical region. In particular, the comparison with experiments shows that all the analyzed models are able to qualitatively predict the dynamical crossover from a liquid-like to a gas-like behavior upon crossing the Widom line. Some of the models perform better in reproducing the pressure-temperature slope of the Widom line of supercritical water once a rigid shift of the phase diagram is applied to bring the critical points to coincide with the experimental ones.

  18. The Widom line and dynamical crossover in supercritical water: Popular water models versus experiments.

    PubMed

    Corradini, D; Rovere, M; Gallo, P

    2015-09-21

    In a previous study [Gallo et al., Nat. Commun. 5, 5806 (2014)], we have shown an important connection between thermodynamic and dynamical properties of water in the supercritical region. In particular, by analyzing the experimental viscosity and the diffusion coefficient obtained in simulations performed using the TIP4P/2005 model, we have found that the line of response function maxima in the one phase region, the Widom line, is connected to a crossover from a liquid-like to a gas-like behavior of the transport coefficients. This is in agreement with recent experiments concerning the dynamics of supercritical simple fluids. We here show how different popular water models (TIP4P/2005, TIP4P, SPC/E, TIP5P, and TIP3P) perform in reproducing thermodynamic and dynamic experimental properties in the supercritical region. In particular, the comparison with experiments shows that all the analyzed models are able to qualitatively predict the dynamical crossover from a liquid-like to a gas-like behavior upon crossing the Widom line. Some of the models perform better in reproducing the pressure-temperature slope of the Widom line of supercritical water once a rigid shift of the phase diagram is applied to bring the critical points to coincide with the experimental ones.

  19. The Widom line and dynamical crossover in supercritical water: Popular water models versus experiments

    NASA Astrophysics Data System (ADS)

    Corradini, D.; Rovere, M.; Gallo, P.

    2015-09-01

    In a previous study [Gallo et al., Nat. Commun. 5, 5806 (2014)], we have shown an important connection between thermodynamic and dynamical properties of water in the supercritical region. In particular, by analyzing the experimental viscosity and the diffusion coefficient obtained in simulations performed using the TIP4P/2005 model, we have found that the line of response function maxima in the one phase region, the Widom line, is connected to a crossover from a liquid-like to a gas-like behavior of the transport coefficients. This is in agreement with recent experiments concerning the dynamics of supercritical simple fluids. We here show how different popular water models (TIP4P/2005, TIP4P, SPC/E, TIP5P, and TIP3P) perform in reproducing thermodynamic and dynamic experimental properties in the supercritical region. In particular, the comparison with experiments shows that all the analyzed models are able to qualitatively predict the dynamical crossover from a liquid-like to a gas-like behavior upon crossing the Widom line. Some of the models perform better in reproducing the pressure-temperature slope of the Widom line of supercritical water once a rigid shift of the phase diagram is applied to bring the critical points to coincide with the experimental ones.

  20. Spousal recovery support, recovery experiences, and life satisfaction crossover among dual-earner couples.

    PubMed

    Park, YoungAh; Fritz, Charlotte

    2015-03-01

    Research has indicated the importance of recovery from work stress for employee well-being and work engagement. However, very little is known about the specific factors that may support or hinder recovery in the context of dual-earner couples. This study proposes spousal recovery support as a potential resource that dual-earner couples can draw on to enhance their recovery experiences and well-being. It was hypothesized that spousal recovery support would be related to the recipient spouse's life satisfaction via his or her own recovery experiences (i.e., psychological detachment, relaxation, and mastery experiences). The study further investigated the crossover of life satisfaction between working spouses as a potential outcome of recovery processes. Data from 318 full-time employed married couples in South Korea were analyzed using structural equation modeling. Results showed that spousal recovery support was positively related to all 3 recovery experiences of the recipient spouse. Moreover, this recovery support was related to the recipient spouse's life satisfaction via relaxation and mastery experiences. Unexpectedly, psychological detachment was negatively related to life satisfaction, possibly indicating a suppression effect. Life satisfaction crossed over between working spouses. No gender differences were found in the hypothesized paths. Based on these findings, theoretical and practical implications are discussed, and future research directions are presented.

  1. Crossover behavior in interface depinning.

    PubMed

    Chen, Y J; Zapperi, Stefano; Sethna, James P

    2015-08-01

    We study the crossover scaling behavior of the height-height correlation function in interface depinning in random media. We analyze experimental data from a fracture experiment and simulate an elastic line model with nonlinear couplings and disorder. Both exhibit a crossover between two different universality classes. For the experiment, we fit a functional form to the universal crossover scaling function. For the model, we vary the system size and the strength of the nonlinear term and describe the crossover between the two universality classes with a multiparameter scaling function. Our method provides a general strategy to extract scaling properties in depinning systems exhibiting crossover phenomena.

  2. Peer Assessment Enhances Student Learning: The Results of a Matched Randomized Crossover Experiment in a College Statistics Class

    PubMed Central

    Sun, Dennis L.; Harris, Naftali; Walther, Guenther; Baiocchi, Michael

    2015-01-01

    Feedback has a powerful influence on learning, but it is also expensive to provide. In large classes it may even be impossible for instructors to provide individualized feedback. Peer assessment is one way to provide personalized feedback that scales to large classes. Besides these obvious logistical benefits, it has been conjectured that students also learn from the practice of peer assessment. However, this has never been conclusively demonstrated. Using an online educational platform that we developed, we conducted an in-class matched-set, randomized crossover experiment with high power to detect small effects. We establish that peer assessment causes a small but significant gain in student achievement. Our study also demonstrates the potential of web-based platforms to facilitate the design of high-quality experiments to identify small effects that were previously not detectable. PMID:26683053

  3. Peer Assessment Enhances Student Learning: The Results of a Matched Randomized Crossover Experiment in a College Statistics Class.

    PubMed

    Sun, Dennis L; Harris, Naftali; Walther, Guenther; Baiocchi, Michael

    2015-01-01

    Feedback has a powerful influence on learning, but it is also expensive to provide. In large classes it may even be impossible for instructors to provide individualized feedback. Peer assessment is one way to provide personalized feedback that scales to large classes. Besides these obvious logistical benefits, it has been conjectured that students also learn from the practice of peer assessment. However, this has never been conclusively demonstrated. Using an online educational platform that we developed, we conducted an in-class matched-set, randomized crossover experiment with high power to detect small effects. We establish that peer assessment causes a small but significant gain in student achievement. Our study also demonstrates the potential of web-based platforms to facilitate the design of high-quality experiments to identify small effects that were previously not detectable.

  4. Crossover from Fingering to Fracturing in Fluid-fluid Displacement in Deformable Granular Media: Theory and Experiments

    NASA Astrophysics Data System (ADS)

    Holtzman, R.; Szulczewski, M.; Darby, J.; Juanes, R.

    2011-12-01

    Predicting and, possibly, controlling the morphology of gas invasion in porous media is critical in many natural and engineered processes like enhanced oil recovery, hydraulic fracturing, methane venting from organic-rich sediments, and filter design. Here, we study fluid-fluid displacement in a deformable granular medium by means of laboratory experiments, computer simulations and scaling analysis. Experimentally, we inject air into a water-saturated glass beads packed in a slender cylindrical container, and record the evolution of the invasion pattern. We have three control variables: the injection rate, the bead size, and the confining stress. Under large confinement, when the granular pack behaves as a rigid medium, the invasion pattern experiences a transition from viscous to capillary fingering by decreasing the injection rate, in agreement with classical results [1]. We show, however, that for a fixed injection rate the system exhibits a crossover from fingering to "fracturing" as the bead size is decreased or the level of confinement is reduced. Thus, fracture opening is the dominant gas invasion mechanism in fine, soft sediments. Our mechanistic model and scaling analysis allow us to rationalize the different regimes of fluid displacement as a function of the properties of the fluids (interfacial tension and viscosity) and solid particles (particle size and stiffness), pore-scale disorder, injection rate and external confinement. We identify two dimensionless groups that describe the interplay between capillarity, viscosity and elasticity, and control the mode of fluid displacement [2].

  5. An Example Crossover Experiment for Testing New Vicarious Calibration Techniques for Satellite Ocean Color Radiometry

    NASA Technical Reports Server (NTRS)

    Voss, Kenneth J.; McLean, Scott; Lewis, Marlon; Johnson, Carol; Flora, Stephanie; Feinholz, Michael; Yarbrough, Mark; Trees, Charles; Twardowski, Mike; Clark, Dennis

    2010-01-01

    Vicarious calibration of ocean color satellites involves the use of accurate surface measurements of water-leaving radiance to update and improve the system calibration of ocean color satellite sensors. An experiment was performed to compare a free-fall technique with the established MOBY measurement. We found in the laboratory that the radiance and irradiance instruments compared well within their estimated uncertainties for various spectral sources. The spectrally averaged differences between the NIST values for the sources and the instruments were less than 2.5% for the radiance sensors and less than 1.5% for the irradiance sensors. In the field, the sensors measuring the above-surface downwelling irradiance performed nearly as well as they had in the laboratory, with an average difference of less than 2%. While the water-leaving radiance, L(sub w) calculated from each instrument agreed in almost all cases within the combined instrument uncertainties (approximately 7%), there was a relative bias between the two instrument classes/techniques that varied spectrally. The spectrally averaged (400 nm to 600 nm) difference between the two instrument classes/techniques was 3.1 %. However the spectral variation resulted in the free fall instruments being 0.2% lower at 450 nm and 5.9% higher at 550 nm. Based on the analysis of one matchup, the bias in the L(sub w), was similar to that observed for L(sub u)(1 m) with both systems, indicating the difference did not come from propagating L(sub u)(1 m) to L(sub w).

  6. An Example Crossover Experiment for Testing New Vicarious Calibration Techniques for Satellite Ocean Color Radiometry

    NASA Technical Reports Server (NTRS)

    Voss, Kenneth J.; McLean, Scott; Lewis, Marlon; Johnson, Carol; Flora, Stephanie; Feinholz, Michael; Yarbrough, Mark; Trees, Charles; Twardowski, Mike; Clark, Dennis

    2010-01-01

    Vicarious calibration of ocean color satellites involves the use of accurate surface measurements of water-leaving radiance to update and improve the system calibration of ocean color satellite sensors. An experiment was performed to compare a free-fall technique with the established MOBY measurement. We found in the laboratory that the radiance and irradiance instruments compared well within their estimated uncertainties for various spectral sources. The spectrally averaged differences between the NIST values for the sources and the instruments were less than 2.5% for the radiance sensors and less than 1.5% for the irradiance sensors. In the field, the sensors measuring the above-surface downwelling irradiance performed nearly as well as they had in the laboratory, with an average difference of less than 2%. While the water-leaving radiance, L(sub w) calculated from each instrument agreed in almost all cases within the combined instrument uncertainties (approximately 7%), there was a relative bias between the two instrument classes/techniques that varied spectrally. The spectrally averaged (400 nm to 600 nm) difference between the two instrument classes/techniques was 3.1 %. However the spectral variation resulted in the free fall instruments being 0.2% lower at 450 nm and 5.9% higher at 550 nm. Based on the analysis of one matchup, the bias in the L(sub w), was similar to that observed for L(sub u)(1 m) with both systems, indicating the difference did not come from propagating L(sub u)(1 m) to L(sub w).

  7. Effects of a 30 kV/m, 60 Hz electric field on the social behavior of baboons: A crossover experiment

    SciTech Connect

    Easley, S.P.; Coelho, A.M. Jr.; Rogers, W.R. )

    1992-01-01

    Using a crossover experimental design, we evaluated our earlier findings that exposure to a 30 kV/m, 60 Hz electric field for 12 hours per day, 7 days per week for 6 weeks produced significant changes in the performance rates of social behaviors among young adult male baboons. In the crossover experiment, the former control group was exposed to a 30 kV/m, 60 Hz electric field for 3 weeks. Only an extremely small, incidental magnetic field was generated by the exposure apparatus. We found that electric-field exposure again produced increases in the performance rates that index Passive Affinity, Tension, and Stereotypy. These findings, combined with results from our other electric-field experiments, indicate that exposure to strong electric fields, in the absence of associated magnetic fields, consistently produces effects that are expressed as increases in rates of performance of social behaviors in young adult male baboons.

  8. [Cross-over studies].

    PubMed

    Bonten, Tobias N; Siegerink, Bob; van der Bom, Johanna G

    2013-01-01

    Randomized, parallel group clinical trials often require large groups of patients; this is expensive and takes time. A randomized cross-over trial can be an efficient and more affordable alternative. A cross-over design can be used to study chronic disorders in which treatments have temporary effects. Participants receive all treatments in consecutive periods and outcomes are measured after every period. In general, only a quarter of the total group size is needed for cross-over studies compared with parallel group studies. Results can be affected by period-effects and carry-over-effects, which can be prevented through randomization and a wash-out period of sufficient length. The dropping-out of participants has more negative consequences for cross-over studies than for parallel group studies.

  9. Making crossovers during meiosis.

    PubMed

    Whitby, M C

    2005-12-01

    Homologous recombination (HR) is required to promote both correct chromosome segregation and genetic variation during meiosis. For this to be successful recombination intermediates must be resolved to generate reciprocal exchanges or 'crossovers' between the homologous chromosomes (homologues) during the first meiotic division. Crossover recombination promotes faithful chromosome segregation by establishing connections (chiasmata) between the homologues, which help guide their proper bipolar alignment on the meiotic spindle. Recent studies of meiotic recombination in both the budding and fission yeasts have established that there are at least two pathways for generating crossovers. One pathway involves the resolution of fully ligated four-way DNA junctions [HJs (Holliday junctions)] by an as yet unidentified endonuclease. The second pathway appears to involve the cleavage of the precursors of ligated HJs, namely displacement (D) loops and unligated/nicked HJs, by the Mus81-Eme1/Mms4 endonuclease.

  10. A matched crossover design for clinical trials.

    PubMed

    Simon, Laura J; Chinchilli, Vernon M

    2007-09-01

    Two design principles are used frequently in clinical trials: 1) A subject is "matched" or "paired" with a similar subject to reduce the chance that other variables obscure the primary comparison of interest. 2) A subject serves as his/her own control by "crossing over" from one treatment to another during the course of an experiment. There are situations in which it may be advantageous to use the two design principles - crossing over and matching - simultaneously. That is, it may be advantageous to conduct a "paired crossover design," in which each subject, while paired with a similar subject, crosses over and receives each experimental treatment. In this paper, we describe two clinical trials conducted by the National Heart, Lung and Blood Institute's Asthma Clinical Research Network that used a paired 2x2 crossover design. The Beta Adrenergic Response by GEnotype (BARGE) Study compared the effects of regular use of inhaled albuterol on mildly asthmatic patients with different genotypes at the 16th position of the beta-agonist receptor gene. The Smoking Modulates Outcomes of Glucocorticoid (SMOG) Therapy in Asthma Study evaluated the hypothesis that smoking reduces the response to inhaled corticosteroids. For such paired crossover designs, the primary parameter of interest is typically the treatment-by-pairing interaction term. In evaluating the relative efficiency of the paired 2x2 crossover design to two independent crossover designs with respect to this interaction term, we show that the paired 2x2 crossover design is more efficient if the correlations between the paired members on the same treatments are greater than their correlations on different treatments. This condition should hold in most circumstances, and therefore the paired crossover design deserves serious consideration for any clinical trial in which the crossing over and matching of subjects is deemed simultaneously beneficial.

  11. Composite-boson approach to molecular Bose-Einstein condensates in mixtures of ultracold Fermi gases

    NASA Astrophysics Data System (ADS)

    Bouvrie, P. Alexander; Tichy, Malte C.; Roditi, Itzhak

    2017-02-01

    We show that an ansatz based on independent composite bosons [Phys. Rep. 463, 215 (2008), 10.1016/j.physrep.2007.11.003] accurately describes the condensate fraction of molecular Bose-Einstein condensates in ultracold Fermi gases. The entanglement between the fermionic constituents of a single Feshbach molecule then governs the many-particle statistics of the condensate, from the limit of strong interaction to close to unitarity. This result strengthens the role of entanglement as the indispensable driver of composite-boson behavior. The condensate fraction of fermion pairs at zero temperature that we compute matches excellently previous results obtained by means of fixed-node diffusion Monte Carlo methods and the Bogoliubov depletion approximation. This paves the way towards the exploration of the BEC-BCS crossover physics in mixtures of cold Fermi gases with an arbitrary number of fermion pairs as well as the implementation of Hong-Ou-Mandel-like interference experiments proposed within coboson theory.

  12. Equation of state of a polarized Fermi gas in the Bose-Einstein-condensate limit

    SciTech Connect

    Alzetto, F.; Leyronas, X.

    2010-04-15

    We present a theoretical study of the BEC-BCS crossover in the Bose-Einstein-condensate (BEC) regime in the case of an unequal number of fermions of two species. We take full account of the composite nature of the dimers made of fermions. In the limit of low densities, we calculate the ground-state energy of the system, or equivalently the chemical potentials of each species, as well as the one-particle gap and the energy of an 'impurity' immersed in a Fermi sea. For the chemical potentials we go up to order (density){sup 4/3}. The results found involve the exact atom-dimer a{sub AD} and dimer-dimer a{sub DD} scattering lengths and therefore include the three- and four-body problems in the many-body problem. We briefly comment on the importance of the different mean-field corrections for recent experiments.

  13. Polaritons and pairing phenomena in Bose-Hubbard mixtures.

    PubMed

    Bhaseen, M J; Hohenadler, M; Silver, A O; Simons, B D

    2009-04-03

    Motivated by recent experiments on cold atomic gases in ultrahigh finesse optical cavities, we consider the two-band Bose-Hubbard model coupled to quantum light. Photoexcitation promotes carriers between the bands, and we study the interplay between Mott insulating behavior and superfluidity. The model displays a U(1)xU(1) symmetry which supports the coexistence of Mott insulating and superfluid phases and yields a rich phase diagram with multicritical points. This symmetry is shared by several other problems of current experimental interest, including two-component Bose gases in optical lattices and the bosonic BEC-BCS crossover for atom-molecule mixtures induced by a Feshbach resonance. We corroborate our findings by numerical simulations.

  14. Chladni Solitons and the Onset of the Snaking Instability for Dark Solitons in Confined Superfluids

    NASA Astrophysics Data System (ADS)

    Muñoz Mateo, A.; Brand, J.

    2014-12-01

    Complex solitary waves composed of intersecting vortex lines are predicted in a channeled superfluid. Their shapes in a cylindrical trap include a cross, spoke wheels, and Greek Φ , and trace the nodal lines of unstable vibration modes of a planar dark soliton in analogy to Chladni's figures of membrane vibrations. The stationary solitary waves extend a family of solutions that include the previously known solitonic vortex and vortex rings. Their bifurcation points from the dark soliton indicating the onset of new unstable modes of the snaking instability are predicted from scale separation for Bose-Einstein condensates (BECs) and superfluid Fermi gases across the BEC-BCS crossover, and confirmed by full numerical calculations. Chladni solitons could be observed in ultracold gas experiments by seeded decay of dark solitons.

  15. Chladni solitons and the onset of the snaking instability for dark solitons in confined superfluids.

    PubMed

    Muñoz Mateo, A; Brand, J

    2014-12-19

    Complex solitary waves composed of intersecting vortex lines are predicted in a channeled superfluid. Their shapes in a cylindrical trap include a cross, spoke wheels, and Greek Φ, and trace the nodal lines of unstable vibration modes of a planar dark soliton in analogy to Chladni's figures of membrane vibrations. The stationary solitary waves extend a family of solutions that include the previously known solitonic vortex and vortex rings. Their bifurcation points from the dark soliton indicating the onset of new unstable modes of the snaking instability are predicted from scale separation for Bose-Einstein condensates (BECs) and superfluid Fermi gases across the BEC-BCS crossover, and confirmed by full numerical calculations. Chladni solitons could be observed in ultracold gas experiments by seeded decay of dark solitons.

  16. Cedarwood: cross-over pressure research

    USDA-ARS?s Scientific Manuscript database

    A series of experiments were conducted to determine the cross-over pressure for cedarwood oil in carbon dioxide. A closed stirrer reactor with an in-line loop connected to the injector of a GC was used to measure the concentration of cedarwood oil in the carbon dioxide. Both neat cedarwood oil as ...

  17. Does Crossover Interference Count in Saccharomyces cerevisiae?

    PubMed Central

    Stahl, Franklin W.; Foss, Henriette M.; Young, Lisa S.; Borts, Rhona H.; Abdullah, M. F. F.; Copenhaver, Gregory P.

    2004-01-01

    We previously proposed a “counting model” for meiotic crossover interference, in which double-strand breaks occur independently and a fixed number of noncrossovers occur between neighboring crossovers. Whereas in some organisms (group I) this simple model alone describes the crossover distribution, in other organisms (group II) an additional assumption—that some crossovers lack interference—improves the fit. Other differences exist between the groups: Group II needs double-strand breaks and some repair functions to achieve synapsis, while repair in group I generally occurs after synapsis is achieved; group II, but not group I, has recombination proteins Dmc1, Mnd1, and Hop2. Here we report experiments in msh4 mutants that are designed to test predictions of the revised model in a group II organism. Further, we interpret these experiments, the above-mentioned differences between group I and II meiosis, and other data to yield the following proposal: Group II organisms use the repair of leptotene breaks to promote synapsis by generating double-Holliday-junction intermediates that lock homologs together (pairing pathway). The possible crossover or noncrossover resolution products of these structures lack interference. In contrast, for both group I and group II, repair during pachytene (disjunction pathway) is associated with interference and generates only two resolution types, whose structures suggest that the Holliday junctions of the repair intermediates are unligated. A crossover arises when such an intermediate is stabilized by a protein that prevents its default resolution to a noncrossover. The protein-binding pattern required for interference depends on clustering of sites that have received, or are normally about to receive, meiotic double-strand breaks. PMID:15454525

  18. Decomposing Multifractal Crossovers

    PubMed Central

    Nagy, Zoltan; Mukli, Peter; Herman, Peter; Eke, Andras

    2017-01-01

    Physiological processes—such as, the brain's resting-state electrical activity or hemodynamic fluctuations—exhibit scale-free temporal structuring. However, impacts common in biological systems such as, noise, multiple signal generators, or filtering by transport function, result in multimodal scaling that cannot be reliably assessed by standard analytical tools that assume unimodal scaling. Here, we present two methods to identify breakpoints or crossovers in multimodal multifractal scaling functions. These methods incorporate the robust iterative fitting approach of the focus-based multifractal formalism (FMF). The first approach (moment-wise scaling range adaptivity) allows for a breakpoint-based adaptive treatment that analyzes segregated scale-invariant ranges. The second method (scaling function decomposition method, SFD) is a crossover-based design aimed at decomposing signal constituents from multimodal scaling functions resulting from signal addition or co-sampling, such as, contamination by uncorrelated fractals. We demonstrated that these methods could handle multimodal, mono- or multifractal, and exact or empirical signals alike. Their precision was numerically characterized on ideal signals, and a robust performance was demonstrated on exemplary empirical signals capturing resting-state brain dynamics by near infrared spectroscopy (NIRS), electroencephalography (EEG), and blood oxygen level-dependent functional magnetic resonance imaging (fMRI-BOLD). The NIRS and fMRI-BOLD low-frequency fluctuations were dominated by a multifractal component over an underlying biologically relevant random noise, thus forming a bimodal signal. The crossover between the EEG signal components was found at the boundary between the δ and θ bands, suggesting an independent generator for the multifractal δ rhythm. The robust implementation of the SFD method should be regarded as essential in the seamless processing of large volumes of bimodal fMRI-BOLD imaging data for

  19. Patient participation in postoperative care activities in patients undergoing total knee replacement surgery: Multimedia Intervention for Managing patient Experience (MIME). Study protocol for a cluster randomised crossover trial.

    PubMed

    McDonall, Jo; de Steiger, Richard; Reynolds, John; Redley, Bernice; Livingston, Patricia; Botti, Mari

    2016-07-18

    Patient participation is an important indicator of quality care. Currently, there is little evidence to support the belief that participation in care is possible for patients during the acute postoperative period. Previous work indicates that there is very little opportunity for patients to participate in care in the acute context. Patients require both capability, in terms of having the required knowledge and understanding of how they can be involved in their care, and the opportunity, facilitated by clinicians, to engage in their acute postoperative care. This cluster randomised crossover trial aims to test whether a multimedia intervention improves patient participation in the acute postoperative context, as determined by pain intensity and recovery outcomes. A total of 240 patients admitted for primary total knee replacement surgery will be invited to participate in a cluster randomised, crossover trial and concurrent process evaluation in at least two wards at a major non-profit private hospital in Melbourne, Australia. Patients admitted to the intervention ward will receive the multimedia intervention daily from Day 1 to Day 5 (or day of discharge, if prior). The intervention will be delivered by nurses via an iPad™, comprising information on the goals of care for each day following surgery. Patients admitted to the control ward will receive usual care as determined by care pathways currently in use across the organization. The primary endpoint is the "worst pain experienced in the past 24 h" on Day 3 following TKR surgery. Pain intensity will be measured using the numerical rating scale. Secondary outcomes are interference of pain on activities of daily living, length of stay in hospital, function and pain following TKR surgery, overall satisfaction with hospitalisation, postoperative complications and hospital readmission. The results of this study will contribute to our understanding of the effectiveness of interventions that provide knowledge and

  20. Experience and challenges presented by a multicenter crossover study of combination analgesic therapy for the treatment of painful HIV-associated polyneuropathies

    PubMed Central

    Harrison, Taylor; Miyahara, Sachiko; Lee, Anthony; Evans, Scott; Bastow, Barbara; Simpson, David; Gilron, Ian; Dworkin, Robert; Daar, Eric S.; Wieclaw, Linda; Clifford, David B.

    2014-01-01

    Objective There is limited evidence for efficacy of analgesics as monotherapy for neuropathic pain associated with HIV-associated polyneuropathies, in spite of demonstrated efficacy in other neuropathic pain conditions. We evaluated the tolerability and analgesic efficacy of duloxetine, methadone, and the combination of duloxetine-methadone compared to placebo. Design This study was a phase II, randomized, double blind, placebo-controlled, four-period crossover multi-center study of analgesic therapy for patients with at least moderate neuropathic pain due to HIV-associated polyneuropathy. Duloxetine, methadone, combination duloxetine-methadone, and placebo were administered in four different possible sequences. The primary outcome measure was mean pain intensity (MPI) measured daily in a study-supplied pain diary. Results A total of 15 patients were enrolled from 8 study sites and 8 patients completed the entire trial. Study treatments failed to show statistically significant change in MPI compared to placebo. Adverse events were frequent and associated with high rates of drug discontinuation and study drop-out. Conclusions Challenges with participant recruitment and poor retention precluded trial completion to its planned targets, limiting our evaluation of the analgesic efficacy of the study treatments. Challenges to successful completion of this study and lessons learned are discussed. PMID:23565581

  1. Double-Blind Crossover Study to Compare Pain Experience During Inferior Alveolar Nerve Block Administration Using Buffered Two Percent Lidocaine in Children.

    PubMed

    Chopra, Radhika; Jindal, Garima; Sachdev, Vinod; Sandhu, Meera

    2016-01-01

    Buffering of anesthetic solutions has been suggested to reduce pain on injection and onset of anesthesia. The purpose of this study was to assess the reduction in pain on injection during inferior alveolar nerve block administration in children. A double blind crossover study was designed where 30 six- to 12-year-old patients received two sessions of inferior alveolar nerve block scheduled one week apart. Two percent lidocaine with 1:200,000 epinephrine was given during one appointment, and a buffered solution was given during the other. Pain on injection was assessed using the sound, eye, and motor (SEM) scale, and the time to onset was assessed after gingival probing. The Heft-Parker visual analogue scale (HP-VAS) was self recorded by the patient after administration of local anesthesia. When tested using Mann-Whitney analysis, no significant differences were found between the SEM scores (P=0.71) and HP-VAS scores (P=0.93) for the two solutions used. Student's t test was used to assess the difference in the onset of anesthesia, which was also found to be statistically insignificant (P=0.824). Buffered lidocaine did not reduce the pain on injection or time to onset of anesthesia for inferior alveolar nerve block in children.

  2. FANCM limits meiotic crossovers.

    PubMed

    Crismani, Wayne; Girard, Chloé; Froger, Nicole; Pradillo, Mónica; Santos, Juan Luis; Chelysheva, Liudmila; Copenhaver, Gregory P; Horlow, Christine; Mercier, Raphaël

    2012-06-22

    The number of meiotic crossovers (COs) is tightly regulated within a narrow range, despite a large excess of molecular precursors. The factors that limit COs remain largely unknown. Here, using a genetic screen in Arabidopsis thaliana, we identified the highly conserved FANCM helicase, which is required for genome stability in humans and yeasts, as a major factor limiting meiotic CO formation. The fancm mutant has a threefold-increased CO frequency as compared to the wild type. These extra COs arise not from the pathway that accounts for most of the COs in wild type, but from an alternate, normally minor pathway. Thus, FANCM is a key factor imposing an upper limit on the number of meiotic COs, and its manipulation holds much promise for plant breeding.

  3. Effects of culinary spices and psychological stress on postprandial lipemia and lipase activity: results of a randomized crossover study and in vitro experiments.

    PubMed

    McCrea, Cindy E; West, Sheila G; Kris-Etherton, Penny M; Lambert, Joshua D; Gaugler, Trent L; Teeter, Danette L; Sauder, Katherine A; Gu, Yeyi; Glisan, Shannon L; Skulas-Ray, Ann C

    2015-01-16

    Data suggest that culinary spices are a potent, low-calorie modality for improving physiological responses to high fat meals. In a pilot study (N = 6 healthy adults), we showed that a meal containing a high antioxidant spice blend attenuated postprandial lipemia by 30% compared to a low spice meal. Our goal was to confirm this effect in a larger sample and to consider the influence of acute psychological stress on fat metabolism. Further, we used in vitro methods to evaluate the inhibitory effect of spices on digestive enzymes. In a 2 x 2, randomized, 4-period crossover design, we compared the effects of 14.5 g spices (black pepper, cinnamon, cloves, garlic, ginger, oregano, paprika, rosemary, and turmeric) vs. placebo incorporated into a high fat meal (1000 kcal, 45 g fat), followed by psychological stress (Trier Social Stress Test) vs. rest on postprandial metabolism in 20 healthy but overweight adults. Blood was sampled at baseline and at 105, 140, 180, and 210 minutes for analysis of triglycerides, glucose, and insulin. Additional in vitro analyses examined the effect of the spice blend and constituent spices on the activity of pancreatic lipase (PL) and secreted phospholipase A₂ (PLA₂). Mixed models were used to model the effects of spices and stress (SAS v9.3). Serum triglycerides, glucose and insulin were elevated following the meal (p < 0.01). Spices reduced post-meal triglycerides by 31% when the meal was followed by the rest condition (p = 0.048), but this effect was not present during stress. There was no effect of the spice blend on glucose or insulin; however, acute stress significantly increased both of these measures (p < 0.01; mean increase of 47% and 19%, respectively). The spice blend and several of the individual spices dose-dependently inhibited PL and PLA2 activity in vitro. Inclusion of spices may attenuate postprandial lipemia via inhibition of PL and PLA₂. However, the impact of psychological stress negates any

  4. Crossover studies with survival outcomes.

    PubMed

    Buyze, Jozefien; Goetghebeur, Els

    2013-12-01

    Crossover designs are well known to have major advantages when comparing the effect of two treatments which do not interact. With a right-censored survival endpoint, however, this design is quickly abandoned in favour of the more costly parallel design. Motivated by human immunodeficiency virus (HIV) prevention studies which lacked power, we evaluate what may be gained in this setting and compare parallel with crossover designs. In a heterogeneous population, we find and explain a substantial increase in power for the crossover study using a non-parametric logrank test. With frailties in a proportional hazards model, crossover designs equally lead to substantially smaller variance for the subject-specific hazard ratio (HR), while the population-averaged HR sees negligible gain. Its efficiency benefit is recovered when the population-averaged HR is reconstructed from estimated subject-specific hazard rates. We derive the time point for treatment crossover that optimizes efficiency and end with the analysis of two recent HIV prevention trials. We find that a Cellulose sulphate trial could have hardly gained efficiency from a crossover design, while a Nonoxynol-9 trial stood to gain substantial power. We conclude that there is a role for effective crossover designs in important classes of survival problems.

  5. Topological crossovers near a quantum critical point

    NASA Astrophysics Data System (ADS)

    Khodel, V. A.; Clark, J. W.; Zverev, M. V.

    2011-09-01

    We study the temperature evolution of the single-particle spectrum ɛ-( p) and quasiparticle momentum distribution n( p) of homogeneous strongly correlated Fermi systems beyond a point where the necessary condition for stability of the Landau state is violated, and the Fermi surface becomes multi-connected by virtue of a topological crossover. Attention is focused on the different non-Fermi-liquid temperature regimes experienced by a phase exhibiting a single additional hole pocket compared with the conventional Landau state. A critical experiment is proposed to elucidate the origin of NFL behavior in dense films of liquid 3He.

  6. Shocks generate crossover behavior in lattice avalanches.

    PubMed

    Burridge, James

    2013-11-22

    A spatial avalanche model is introduced, in which avalanches increase stability in the regions where they occur. Instability is driven globally by a driving process that contains shocks. The system is typically subcritical, but the shocks occasionally lift it into a near- or supercritical state from which it rapidly retreats due to large avalanches. These shocks leave behind a signature-a distinct power-law crossover in the avalanche size distribution. The model is inspired by landslide field data, but the principles may be applied to any system that experiences stabilizing failures, possesses a critical point, and is subject to an ongoing process of destabilization that includes occasional dramatic destabilizing events.

  7. Separable Crossover-Promoting and Crossover-Constraining Aspects of Zip1 Activity during Budding Yeast Meiosis

    PubMed Central

    Voelkel-Meiman, Karen; Johnston, Cassandra; Thappeta, Yashna; Subramanian, Vijayalakshmi V.; Hochwagen, Andreas; MacQueen, Amy J.

    2015-01-01

    Accurate chromosome segregation during meiosis relies on the presence of crossover events distributed among all chromosomes. MutSγ and MutLγ homologs (Msh4/5 and Mlh1/3) facilitate the formation of a prominent group of meiotic crossovers that mature within the context of an elaborate chromosomal structure called the synaptonemal complex (SC). SC proteins are required for intermediate steps in the formation of MutSγ-MutLγ crossovers, but whether the assembled SC structure per se is required for MutSγ-MutLγ-dependent crossover recombination events is unknown. Here we describe an interspecies complementation experiment that reveals that the mature SC is dispensable for the formation of Mlh3-dependent crossovers in budding yeast. Zip1 forms a major structural component of the budding yeast SC, and is also required for MutSγ and MutLγ-dependent crossover formation. Kluyveromyces lactis ZIP1 expressed in place of Saccharomyces cerevisiae ZIP1 in S. cerevisiae cells fails to support SC assembly (synapsis) but promotes wild-type crossover levels in those nuclei that progress to form spores. While stable, full-length SC does not assemble in S. cerevisiae cells expressing K. lactis ZIP1, aggregates of K. lactis Zip1 displayed by S. cerevisiae meiotic nuclei are decorated with SC-associated proteins, and K. lactis Zip1 promotes the SUMOylation of the SC central element protein Ecm11, suggesting that K. lactis Zip1 functionally interfaces with components of the S. cerevisiae synapsis machinery. Moreover, K. lactis Zip1-mediated crossovers rely on S. cerevisiae synapsis initiation proteins Zip3, Zip4, Spo16, as well as the Mlh3 protein, as do the crossovers mediated by S. cerevisiae Zip1. Surprisingly, however, K. lactis Zip1-mediated crossovers are largely Msh4/Msh5 (MutSγ)-independent. This separation-of-function version of Zip1 thus reveals that neither assembled SC nor MutSγ is required for Mlh3-dependent crossover formation per se in budding yeast. Our data

  8. Microelectronic superconducting crossover and coil

    DOEpatents

    Wellstood, Frederick C.; Kingston, John J.; Clarke, John

    1994-01-01

    A microelectronic component comprising a crossover is provided comprising a substrate, a first high T.sub.c superconductor thin film, a second insulating thin film comprising SrTiO.sub.3 ; and a third high T.sub.c superconducting film which has strips which crossover one or more areas of the first superconductor film. An in situ method for depositing all three films on a substrate is provided which does not require annealing steps and which can be opened to the atmosphere between depositions.

  9. Tunneling above the crossover temperature.

    PubMed

    Alvarez-Barcia, Sonia; Flores, Jesús R; Kästner, Johannes

    2014-01-09

    Quantum mechanical tunneling of atoms plays a significant role in many chemical reactions. The crossover temperature between classical and quantum movement is a convenient preliminary indication of the importance of tunneling for a particular reaction. Here we show, using instanton theory, that quantum tunneling is possible significantly above this crossover temperature for specific forms of the potential energy surface. We demonstrate the effect on an analytic potential as well as a chemical system. While protons move asynchronously along a Grotthuss chain in the classical high-temperature range, the onset of tunneling results in a synchronization of their movement.

  10. The BCS-BEC Crossover

    NASA Astrophysics Data System (ADS)

    Parish, Meera M.

    2015-09-01

    This chapter presents the crossover from the Bardeen-Cooper-Schrieffer (BCS) state of weakly correlated pairs of fermions to the Bose-Einstein condensation (BEC) of diatomic molecules in the atomic Fermi gas. Our aim is to provide a pedagogical review of the BCS-BEC crossover, with an emphasis on the basic concepts, particularly those that are not generally known or are difficult to find in the literature. We shall not attempt to give an exhaustive survey of current research in the limited space here; where possible, we will direct the reader to more extensive reviews.

  11. Microelectronic superconducting crossover and coil

    DOEpatents

    Wellstood, F.C.; Kingston, J.J.; Clarke, J.

    1994-03-01

    A microelectronic component comprising a crossover is provided comprising a substrate, a first high T[sub c] superconductor thin film, a second insulating thin film comprising SrTiO[sub 3]; and a third high T[sub c] superconducting film which has strips which crossover one or more areas of the first superconductor film. An in situ method for depositing all three films on a substrate is provided which does not require annealing steps and which can be opened to the atmosphere between depositions. 13 figures.

  12. Crossover Interference on Nucleolus Organizing Region-Bearing Chromosomes in Arabidopsis

    PubMed Central

    Lam, Sandy Y.; Horn, Sarah R.; Radford, Sarah J.; Housworth, Elizabeth A.; Stahl, Franklin W.; Copenhaver, Gregory P.

    2005-01-01

    In most eukaryotes, crossovers are not independently distributed along the length of a chromosome. Instead, they appear to avoid close proximity to one another—a phenomenon known as crossover interference. Previously, for three of the five Arabidopsis chromosomes, we measured the strength of interference and suggested a model wherein some crossovers experience interference while others do not. Here we show, using the same model, that the fraction of interference-insensitive crossovers is significantly smaller on the remaining two chromosomes. Since these two chromosomes bear the Arabidopsis NOR domains, the possibility that these chromosomal regions influence interference is discussed. PMID:15802520

  13. Crossover interference on nucleolus organizing region-bearing chromosomes in Arabidopsis.

    PubMed

    Lam, Sandy Y; Horn, Sarah R; Radford, Sarah J; Housworth, Elizabeth A; Stahl, Franklin W; Copenhaver, Gregory P

    2005-06-01

    In most eukaryotes, crossovers are not independently distributed along the length of a chromosome. Instead, they appear to avoid close proximity to one another--a phenomenon known as crossover interference. Previously, for three of the five Arabidopsis chromosomes, we measured the strength of interference and suggested a model wherein some crossovers experience interference while others do not. Here we show, using the same model, that the fraction of interference-insensitive crossovers is significantly smaller on the remaining two chromosomes. Since these two chromosomes bear the Arabidopsis NOR domains, the possibility that these chromosomal regions influence interference is discussed.

  14. Geometric crossovers for multiway graph partitioning.

    PubMed

    Moraglio, Alberto; Kim, Yong-Hyuk; Yoon, Yourim; Moon, Byung-Ro

    2007-01-01

    Geometric crossover is a representation-independent generalization of the traditional crossover defined using the distance of the solution space. By choosing a distance firmly rooted in the syntax of the solution representation as a basis for geometric crossover, one can design new crossovers for any representation. Using a distance tailored to the problem at hand, the formal definition of geometric crossover allows us to design new problem-specific crossovers that embed problem-knowledge in the search. The standard encoding for multiway graph partitioning is highly redundant: each solution has a number of representations, one for each way of labeling the represented partition. Traditional crossover does not perform well on redundant encodings. We propose a new geometric crossover for graph partitioning based on a labeling-independent distance that filters out the redundancy of the encoding. A correlation analysis of the fitness landscape based on this distance shows that it is well suited to graph partitioning. A second difficulty with designing a crossover for multiway graph partitioning is that of feasibility: in general recombining feasible partitions does not lead to feasible offspring partitions. We design a new geometric crossover for permutations with repetitions that naturally suits partition problems and we test it on the graph partitioning problem. We then combine it with the labeling-independent crossover and obtain a much superior geometric crossover inheriting both advantages.

  15. 30 CFR 57.11013 - Conveyor crossovers.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Conveyor crossovers. 57.11013 Section 57.11013... Escapeways Travelways-Surface and Underground § 57.11013 Conveyor crossovers. Crossovers shall be provided where it is necessary to cross conveyors....

  16. 30 CFR 57.11013 - Conveyor crossovers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Conveyor crossovers. 57.11013 Section 57.11013... Escapeways Travelways-Surface and Underground § 57.11013 Conveyor crossovers. Crossovers shall be provided where it is necessary to cross conveyors....

  17. 30 CFR 56.11013 - Conveyor crossovers.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Conveyor crossovers. 56.11013 Section 56.11013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Conveyor crossovers. Crossovers shall be provided where it is necessary to cross conveyors....

  18. 30 CFR 57.11013 - Conveyor crossovers.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Conveyor crossovers. 57.11013 Section 57.11013... Escapeways Travelways-Surface and Underground § 57.11013 Conveyor crossovers. Crossovers shall be provided where it is necessary to cross conveyors....

  19. 30 CFR 56.11013 - Conveyor crossovers.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Conveyor crossovers. 56.11013 Section 56.11013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Conveyor crossovers. Crossovers shall be provided where it is necessary to cross conveyors....

  20. 30 CFR 56.11013 - Conveyor crossovers.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Conveyor crossovers. 56.11013 Section 56.11013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Conveyor crossovers. Crossovers shall be provided where it is necessary to cross conveyors....

  1. 30 CFR 57.11013 - Conveyor crossovers.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Conveyor crossovers. 57.11013 Section 57.11013... Escapeways Travelways-Surface and Underground § 57.11013 Conveyor crossovers. Crossovers shall be provided where it is necessary to cross conveyors....

  2. 30 CFR 56.11013 - Conveyor crossovers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Conveyor crossovers. 56.11013 Section 56.11013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Conveyor crossovers. Crossovers shall be provided where it is necessary to cross conveyors....

  3. 30 CFR 56.11013 - Conveyor crossovers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Conveyor crossovers. 56.11013 Section 56.11013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Conveyor crossovers. Crossovers shall be provided where it is necessary to cross conveyors....

  4. 30 CFR 57.11013 - Conveyor crossovers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Conveyor crossovers. 57.11013 Section 57.11013... Escapeways Travelways-Surface and Underground § 57.11013 Conveyor crossovers. Crossovers shall be provided where it is necessary to cross conveyors....

  5. Subcritical-supercritical bifurcation crossover in directional solidification

    SciTech Connect

    Liu, D.; Williams, L.; Cummins, H. )

    1994-12-01

    The Mullins-Sekerka planar-cellular instability in directional solidification should be subcritical when the partition coefficient [ital k][lt]0.45 and latent heat is ignored. However, Merchant and Davis [Phys. Rev. Lett. [bold 63], 573 (1989)] predicted that as the solute concentration is reduced, the increasingly important thermal diffusion field would lead to a crossover from a subcritical to a supercritical bifurcation. We have performed directional solidification experiments on a series of succinonitrile samples containing different concentrations of Coumarin 152, and have found preliminary evidence for the predicted crossover at a concentration [ital C][sub [ital t

  6. Solving the Traveling Salesman Problem through Extended Changing Crossover Operators

    NASA Astrophysics Data System (ADS)

    Takahashi, Ryouei

    In order to efficiently obtain an approximate solution of the traveling salesman problem (TSP), extended changing crossover operators (ECXOs) which can substitute any crossover operator of genetic algorithms (GAs) and ant colony optimization (ACO) for another crossover operator at any time is proposed. In this investigation our ECXO uses both EX (or ACO) and EXX (Edge Exchange Crossover) in early generations to create local optimum sub-paths, and it uses EAX (Edge Assembly Crossover) to create a global optimum solution after generations. With EX or ACO any individual or any ant determines the next city he visits from lengths of edges or tours' lengths deposited on edges as pheromone, and he generates local optimum paths. With EXX the generated path converges to a provisional optimal path. With EAX a parent exchanges his edges with another parent's ones reciprocally to create sub-cyclic paths, before restructuring a cyclic path by combining the sub-cyclic paths with making distances between them minimum. In this paper validity of ECXO is verified by our C experiments using medium-sized problems in TSPLIB, and it is shown that ECXO can find the best solution earlier than EAX.

  7. Diffusion Dynamics of Water Molecules in a LiCl Solution: a Low-Temperature Crossover

    SciTech Connect

    Mamontov, Eugene

    2009-01-01

    A quasielastic neutron scattering experiment probing the dynamics of water molecules on the pico- to nanosecond time scale in an aqueous solution of lithium chloride has detected a crossover at about 220-230 K between the high-temperature non-Arrhenius and low-temperature Arrhenius behavior. This is the first experiment where the crossover in the dynamics of water molecules is detected in bulk rather than in confinement. The results suggest that the dynamic crossover observed in the current and many recent experiments is not linked to the specific properties of water; instead, it may represent a more general dynamic transition.

  8. Dimensional crossover in semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    McDonald, Matthew P.; Chatterjee, Rusha; Si, Jixin; Jankó, Boldizsár; Kuno, Masaru

    2016-08-01

    Recent advances in semiconductor nanostructure syntheses provide unprecedented control over electronic quantum confinement and have led to extensive investigations of their size- and shape-dependent optical/electrical properties. Notably, spectroscopic measurements show that optical bandgaps of one-dimensional CdSe nanowires are substantially (approximately 100 meV) lower than their zero-dimensional counterparts for equivalent diameters spanning 5-10 nm. But what, exactly, dictates the dimensional crossover of a semiconductor's electronic structure? Here we probe the one-dimensional to zero-dimensional transition of CdSe using single nanowire/nanorod absorption spectroscopy. We find that carrier electrostatic interactions play a fundamental role in establishing dimensional crossover. Moreover, the critical length at which this transition occurs is governed by the aspect ratio-dependent interplay between carrier confinement and dielectric contrast/confinement energies.

  9. Dimensional crossover in semiconductor nanostructures

    PubMed Central

    McDonald, Matthew P.; Chatterjee, Rusha; Si, Jixin; Jankó, Boldizsár; Kuno, Masaru

    2016-01-01

    Recent advances in semiconductor nanostructure syntheses provide unprecedented control over electronic quantum confinement and have led to extensive investigations of their size- and shape-dependent optical/electrical properties. Notably, spectroscopic measurements show that optical bandgaps of one-dimensional CdSe nanowires are substantially (approximately 100 meV) lower than their zero-dimensional counterparts for equivalent diameters spanning 5–10 nm. But what, exactly, dictates the dimensional crossover of a semiconductor's electronic structure? Here we probe the one-dimensional to zero-dimensional transition of CdSe using single nanowire/nanorod absorption spectroscopy. We find that carrier electrostatic interactions play a fundamental role in establishing dimensional crossover. Moreover, the critical length at which this transition occurs is governed by the aspect ratio-dependent interplay between carrier confinement and dielectric contrast/confinement energies. PMID:27577091

  10. Linear combinations come alive in crossover designs.

    PubMed

    Shuster, Jonathan J

    2017-10-30

    Before learning anything about statistical inference in beginning service courses in biostatistics, students learn how to calculate the mean and variance of linear combinations of random variables. Practical precalculus examples of the importance of these exercises can be helpful for instructors, the target audience of this paper. We shall present applications to the "1-sample" and "2-sample" methods for randomized short-term 2-treatment crossover studies, where patients experience both treatments in random order with a "washout" between the active treatment periods. First, we show that the 2-sample method is preferred as it eliminates "conditional bias" when sample sizes by order differ and produces a smaller variance. We also demonstrate that it is usually advisable to use the differences in posttests (ignoring baseline and post washout values) rather than the differences between the changes in treatment from the start of the period to the end of the period ("delta of delta"). Although the intent is not to provide a definitive discussion of crossover designs, we provide a section and references to excellent alternative methods, where instructors can provide motivation to students to explore the topic in greater detail in future readings or courses. Copyright © 2017 John Wiley & Sons, Ltd.

  11. Crossover behavior in driven cascades.

    PubMed

    Burridge, James

    2013-09-01

    We propose a model which explains how power-law crossover behavior can arise in a system which is capable of experiencing cascading failure. In our model the susceptibility of the system to cascades is described by a single number, the propagation power, which measures the ease with which cascades propagate. Physically, such a number could represent the density of unstable material in a system, its internal connectivity, or the mean susceptibility of its component parts to failure. We assume that the propagation power follows an upward drifting Brownian motion between cascades, and drops discontinuously each time a cascade occurs. Cascades are described by a continuous state branching process with distributional properties determined by the value of the propagation power when they occur. In common with many cascading models, pure power-law behavior is exhibited at a critical level of propagation power, and the mean cascade size diverges. This divergence constrains large systems to the subcritical region. We show that as a result, crossover behavior appears in the cascade distribution when an average is performed over the distribution of propagation power. We are able to analytically determine the exponents before and after the crossover.

  12. The BCS Bose crossover theory

    NASA Astrophysics Data System (ADS)

    Adhikari, S. K.; de Llano, M.; Sevilla, F. J.; Solís, M. A.; Valencia, J. J.

    2007-03-01

    We contrast four distinct versions of the BCS-Bose statistical crossover theory according to the form assumed for the electron-number equation that accompanies the BCS gap equation. The four versions correspond to explicitly accounting for two-hole-(2h) as well as two-electron-(2e) Cooper pairs (CPs), or both in equal proportions, or only either kind. This follows from a recent generalization of the Bose-Einstein condensation (GBEC) statistical theory that includes not boson-boson interactions but rather 2e- and also (without loss of generality) 2h-CPs interacting with unpaired electrons and holes in a single-band model that is easily converted into a two-band model. The GBEC theory is essentially an extension of the Friedberg-Lee 1989 BEC theory of superconductors that excludes 2h-CPs. It can thus recover, when the numbers of 2h- and 2e-CPs in both BE-condensed and non-condensed states are separately equal, the BCS gap equation for all temperatures and couplings as well as the zero-temperature BCS (rigorous-upper-bound) condensation energy for all couplings. But ignoring either 2h- or 2e-CPs it can do neither. In particular, only half the BCS condensation energy is obtained in the two crossover versions ignoring either kind of CPs. We show how critical temperatures Tc from the original BCS-Bose crossover theory in 2D require unphysically large couplings for the Cooper/BCS model interaction to differ significantly from the Tcs of ordinary BCS theory (where the number equation is substituted by the assumption that the chemical potential equals the Fermi energy).

  13. Crossover Designs in Nutrition and Dietetics Research.

    PubMed

    Harris, Jeffrey E; Raynor, Hollie A

    2017-07-01

    This article is the 12th installment in a statistical series exploring the importance of research design, epidemiologic methods, and statistical analysis as applied to nutrition and dietetics research. The purpose of this series is to assist registered dietitian nutritionists in interpreting nutrition research and aid nutrition researchers in applying scientific principles to produce high-quality nutrition research. This article focuses on the use of crossover designs in nutrition and dietetics research. The purpose is to distinguish the crossover design from the randomized clinical trial, define important terms, illustrate a 2×2 crossover design, discuss potential confounding variables in the crossover design, describe the analysis and interpretation of crossover data, present sample size considerations, provide examples of the use of the crossover design in nutrition and dietetics, and discuss additional considerations when the independent variable has more than two levels. Copyright © 2017 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

  14. Crossover and parallel study of oral analgesics.

    PubMed

    Wang, R I; Waite, E

    1981-04-01

    Ten years ago, analgesics were studied using crossover designs. In recent years, analgesics have been studied only in parallel designs primarily because biostatisticians do not like crossover studies. The advantages of crossover studies are numerous: (1) patients serve as their own control; (2) there is less variability of responses among patients; and (3) a smaller number of patients is needed to provide statistically significant data. As long as crossover of treatment medications does not occur within 4 to 6 hours, the problem of carryover effect of the previous medication is insignificant or negligible. Two studies will be presented. One is a crossover study of Percodan with and without naloxone to placebo. The other is a parallel study comparing the effects of propoxyphene with naloxone to those of propoxyphene alone. The results of these studies reaffirm the value of the crossover method of evaluating analgesics.

  15. Becoming a crossover-competent DSB.

    PubMed

    Lake, Cathleen M; Hawley, R Scott

    2016-06-01

    The proper execution of meiotic recombination (or crossing over) is essential for chromosome segregation during the first meiotic division, and thus this process is regulated by multiple, and often elaborate, mechanisms. Meiotic recombination begins with the programmed induction of DNA double-strand breaks (DSBs), of which only a subset are selected to be repaired into crossovers. This crossover selection process is carried out by a number of pro-crossover proteins that regulate the fashion in which DSBs are repaired. Here, we highlight recent studies regarding the process of DSB fate selection by a family of pro-crossover proteins known as the Zip-3 homologs.

  16. Crossover dynamics at large metastability in gas-liquid nucleation.

    PubMed

    Santra, Mantu; Bagchi, Biman

    2011-03-01

    We have developed an alternate description of dynamics of nucleation in terms of an extended set of order parameters. The order parameters consist of an ordered set of kth largest clusters, ordered such that k= 1 is the largest cluster in the system, k= 2 is the second largest cluster, and so on. We have derived an analytic expression for the free energy for the kth largest cluster, which is in excellent agreement with the simulated results. At large supersaturation, the free energy barrier for the growth of the kth largest cluster disappears and the nucleation becomes barrierless. The major success of this extended theoretical formalism is that it can clearly explain the observed change in mechanism at large metastability [P. Bhimalapuram et al., Phys. Rev. Lett. 98, 206104 (2007)] and the associated dynamical crossover. The classical nucleation theory cannot explain this crossover. The crossover from activated to barrierless nucleation is found to occur at a supersaturation where multiple clusters cross the critical size. We attribute the crossover as the onset of the kinetic spinodal. We have derived an expression for the rate of nucleation in the barrierless regime by modeling growth as diffusion on the free energy surface of the largest cluster. The model reproduces the slower increase in the rate of growth as a function of supersaturation, as observed in experiments.

  17. Biases in Attentional Orientation and Magnitude Estimation Explain Crossover: Neglect is a Disorder of Both

    PubMed Central

    Mennemeier, Mark; Pierce, Christopher A.; Chatterjee, Anjan; Anderson, Britt; Jewell, George; Dowler, Rachael; Woods, Adam J.; Glenn, Tannahill; Mark, Victor W.

    2015-01-01

    Crossover refers to a pattern of performance on the line bisection test in which short lines are bisected on the side opposite the true center of long lines. Although most patients with spatial neglect demonstrate crossover, contemporary theories of neglect cannot explain it. In contrast, we show that blending the psychophysical construct of magnitude estimation with neglect theory not only explains crossover, but also addresses a quantitative feature of neglect that is independent of spatial deficits. We report a prospective validation study of the orientation/estimation hypothesis of crossover. Forty subjects (17 patients with and without neglect following unilateral brain injury and 23 normal controls) completed four experiments that examined crossover using line bisection, line bisection with cueing, and reproducing line lengths from both memory and a standard. Replicating earlier findings, all except one subject group exhibited crossover on the standard line bisection test, all groups showed a spontaneous preference to orient attention to one end of the lines, and all groups overestimated the length of short lines and underestimated long lines. Biases in attentional orientation and magnitude estimation are exaggerated in patients with neglect. The truly novel finding of this study occurred when, after removing the line from the bisection task, the direction of crossover was completely reversed in all subject groups depending on where attention was oriented. These findings are consistent with our hypothesis of crossover: (1) crossover is a normal component of performance on line bisection; (2) crossover results from the interplay of biases in attentional orientation and magnitude estimation; and (3) attentional orientation predicts the direction of crossover, whereas a disorder of magnitude estimation, not previously emphasized in neglect, accounts for the quantitative changes in length estimation that make crossover more obvious in neglect subjects

  18. Biases in attentional orientation and magnitude estimation explain crossover: neglect is a disorder of both.

    PubMed

    Mennemeier, Mark; Pierce, Christopher A; Chatterjee, Anjan; Anderson, Britt; Jewell, George; Dowler, Rachael; Woods, Adam J; Glenn, Tannahill; Mark, Victor W

    2005-08-01

    Crossover refers to a pattern of performance on the line bisection test in which short lines are bisected on the side opposite the true center of long lines. Although most patients with spatial neglect demonstrate crossover, contemporary theories of neglect cannot explain it. In contrast, we show that blending the psychophysical construct of magnitude estimation with neglect theory not only explains crossover, but also addresses a quantitative feature of neglect that is independent of spatial deficits. We report a prospective validation study of the orientation/estimation hypothesis of crossover. Forty subjects (17 patients with and without neglect following unilateral brain injury and 23 normal controls) completed four experiments that examined crossover using line bisection, line bisection with cueing, and reproducing line lengths from both memory and a standard. Replicating earlier findings, all except one subject group exhibited crossover on the standard line bisection test, all groups showed a spontaneous preference to orient attention to one end of the lines, and all groups overestimated the length of short lines and underestimated long lines. Biases in attentional orientation and magnitude estimation are exaggerated in patients with neglect. The truly novel finding of this study occurred when, after removing the line from the bisection task, the direction of crossover was completely reversed in all subject groups depending on where attention was oriented. These findings are consistent with our hypothesis of crossover: (1) crossover is a normal component of performance on line bisection; (2) crossover results from the interplay of biases in attentional orientation and magnitude estimation; and (3) attentional orientation predicts the direction of crossover, whereas a disorder of magnitude estimation, not previously emphasized in neglect, accounts for the quantitative changes in length estimation that make crossover more obvious in neglect subjects

  19. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Electrical crossovers. 3285.701... URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Electrical Systems and Equipment § 3285.701 Electrical crossovers. Multi-section homes with electrical wiring in more than one section require...

  20. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false Electrical crossovers. 3285.701... URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Electrical Systems and Equipment § 3285.701 Electrical crossovers. Multi-section homes with electrical wiring in more than one section require...

  1. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 false Electrical crossovers. 3285.701... URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Electrical Systems and Equipment § 3285.701 Electrical crossovers. Multi-section homes with electrical wiring in more than one section...

  2. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 5 2013-04-01 2013-04-01 false Electrical crossovers. 3285.701... URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Electrical Systems and Equipment § 3285.701 Electrical crossovers. Multi-section homes with electrical wiring in more than one section...

  3. 24 CFR 3285.701 - Electrical crossovers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 5 2012-04-01 2012-04-01 false Electrical crossovers. 3285.701... URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Electrical Systems and Equipment § 3285.701 Electrical crossovers. Multi-section homes with electrical wiring in more than one section...

  4. Meiotic crossover patterns: Obligatory crossover, interference and homeostasis in a single process

    PubMed Central

    Wang, Shunxin; Zickler, Denise; Kleckner, Nancy; Zhang, Liangran

    2015-01-01

    During meiosis, crossover recombination is tightly regulated. A spatial patterning phenomenon known as interference ensures that crossovers are well-spaced along the chromosomes. Additionally, every pair of homologs acquires at least one crossover. A third feature, crossover homeostasis, buffers the system such that the number of crossovers remains steady despite decreases or increases in the number of earlier recombinational interactions. Here we summarize recent work from our laboratory supporting the idea that all 3 of these aspects are intrinsic consequences of a single basic process and suggesting that the underlying logic of this process corresponds to that embodied in a particular (beam-film) model. PMID:25590558

  5. An end to crossover designs for studies on the effect of sugar substitutes on caries?

    PubMed

    Mäkinen, K K

    2009-01-01

    Clinical trials and laboratory studies involving the administration of oral health treatments and foods have benefited from the observance of the so-called crossover study design. Field experience and a growing number of laboratory experiments have shown, however, that 'blind' reliance on crossover designs may in some instances lead to unexpected results and erroneous conclusions. Some dietary substances, antibiotic agents, and even fluoride applications may have long-term effects that call into question the appropriateness of the washout periods between treatments. Studies have also been conducted on compounds that have turned out to display synergistic effects. When long-term and synergistic effects are simultaneously present in trials involving a crossover design, difficulties may arise in the interpretation of results. This communication uses as an example the long-term clinical and microbiological effects of xylitol and suggests that inclusion of the crossover practice in clinical trials should be separately and carefully contemplated in each instance.

  6. The choice in meiosis - defining the factors that influence crossover or non-crossover formation.

    PubMed

    Youds, Jillian L; Boulton, Simon J

    2011-02-15

    Meiotic crossovers are essential for ensuring correct chromosome segregation as well as for creating new combinations of alleles for natural selection to take place. During meiosis, excess meiotic double-strand breaks (DSBs) are generated; a subset of these breaks are repaired to form crossovers, whereas the remainder are repaired as non-crossovers. What determines where meiotic DSBs are created and whether a crossover or non-crossover will be formed at any particular DSB remains largely unclear. Nevertheless, several recent papers have revealed important insights into the factors that control the decision between crossover and non-crossover formation in meiosis, including DNA elements that determine the positioning of meiotic DSBs, and the generation and processing of recombination intermediates. In this review, we focus on the factors that influence DSB positioning, the proteins required for the formation of recombination intermediates and how the processing of these structures generates either a crossover or non-crossover in various organisms. A discussion of crossover interference, assurance and homeostasis, which influence crossing over on a chromosome-wide and genome-wide scale - in addition to current models for the generation of interference - is also included. This Commentary aims to highlight recent advances in our understanding of the factors that promote or prevent meiotic crossing over.

  7. Crossover critical phenomena in fluids

    NASA Astrophysics Data System (ADS)

    Kostrowicka Wyczalkowska, Anna Judyta

    In fluids the effects of critical density fluctuations remain significant over a large range of temperatures and densities. The nonanalytical behavior observed in real fluids in the vicinity of the critical point is well described by renormalization-group theory. This theory accounts properly for the influence of the critical fluctuations in density which are entirely neglected by the classical equations. Specifically, fluids asymptotically close to the critical point belong to the universality class of the 3-dimensional Ising model and their behavior near the critical point is governed by scaling laws with critical exponents appropriate for this universality class. The validity of the asymptotic power laws is, however, restricted to a very small region near the critical point. An approach to deal with the nonasymptotic behavior of fluids including the crossover from Ising behavior in the immediate vicinity of the critical point to classical behavior far away from the critical point has been developed by Chen and coworkers and is further improved in this thesis. This approach is based on earlier work of Nicoll and coworkers and it leads to a transformation of a classical Landau expansion to incorporate the effects of critical fluctuations. Here we show how this transformation applies to real fluids: water and sulfurhexafluoride. Nevertheless, even such a crossover Landau expansion still fails to make a connection with the behavior of the fluid very far away from the critical point like the ideal-gas limit at low densities. We demonstrate how a procedure, earlier developed to include the effects of critical fluctuations into a classical Landau expansion of the Helmholtz-energy density, can also be applied to a closed-form classical equation of state like the equation of van der Waals. One of the consequences of accounting for the presence of the critical fluctuations is a shift in the location of the critical point. The resulting equation incorporates the

  8. Thermodynamics of ultracold Bose gases at a dimensional crossover

    NASA Astrophysics Data System (ADS)

    Labouvie, Ralf; Vogler, Andreas; Guarrera, Vera; Ott, Herwig

    2013-05-01

    We have studied the thermodynamics of ultracold Bose gases in the crossover from a three-dimensional to a one-dimensional regime. In our experiment, we use a focused electron-beam to probe in situ atomic density distributions with high temporal and spatial resolution. Starting with a Bose-Einstein-Condensate in a single beam optical dipole trap we can create one-dimensional systems by loading the atoms in a two-dimensional blue-detuned optical lattice. With increasing strength of the lattices we go from a three-dimensional into a one-dimensional system. Furthermore we tune the interaction strengths of the one-dimensional quantum-gases from weak (quasi-condensate) to strong (Tonks-Girardeau). By measuring the density profiles and applying an inverse Abel-Transformation we extract the equation of states of these systems and characterize the crossover from the three-dimensional to the one-dimensional regime.

  9. Splitter imperfections in annular split-flow thin separation channels: experimental study of nonspecific crossover.

    PubMed

    Williams, P Stephen; Decker, Keith; Nakamura, Masayuki; Chalmers, Jeffrey J; Moore, Lee R; Zborowski, Maciej

    2003-12-01

    The separation performance of a split-flow thin (SPLITT) separation device depends on uniformity of channel thickness and the precise placement of the flow splitters at fixed distances between the channel walls. The observation of nonspecific crossover, that is, the transport of sample materials across the channel thickness without the influence of an applied field, has routinely been taken to indicate the presence of irregularities in splitter shape or placement. Computational fluid dynamics software may be used to predict the influence of splitter imperfections on nonspecific crossover, where it is assumed that sample transport is by convection alone. A previous study has shown how small inlet splitter imperfections can account for the relatively low levels of nonspecific crossover observed with typical annular SPLITT devices. This study, however, could not distinguish between the possible sources of nonspecific crossover; hydrodynamic lift or shear-induced diffusion could have contributed. To confirm the validity of the computational approach, a series of experiments has been carried out on a channel having a deliberately and severely bent splitter. Nonspecific crossover was measured for a range of inlet and outlet flow rate ratios, with the bent splitter placed at both the channel inlet and outlet. The severity of the splitter distortion was sufficient to produce significant nonspecific crossover over a wide range of flow conditions. Good agreement was found between experiment and prediction based on computational fluid dynamics, with experiment generally showing only slightly higher crossover than prediction. The quantitative agreement for this extreme case suggests that the contribution to nonspecific crossover due to geometrical imperfections can be well described using computational fluid dynamics.

  10. Direct observation in 3d of structural crossover in binary hard sphere mixtures

    NASA Astrophysics Data System (ADS)

    Statt, Antonia; Pinchaipat, Rattachai; Turci, Francesco; Evans, Robert; Royall, C. Patrick

    2016-04-01

    For binary fluid mixtures of spherical particles in which the two species are sufficiently different in size, the dominant wavelength of oscillations of the pair correlation functions is predicted to change from roughly the diameter of the large species to that of the small species along a sharp crossover line in the phase diagram [C. Grodon et al., J. Chem. Phys. 121, 7869 (2004)]. Using particle-resolved colloid experiments in 3d we demonstrate that crossover exists and that its location in the phase diagram is in quantitative agreement with the results of both theory and our Monte-Carlo simulations. In contrast with previous work [J. Baumgartl et al., Phys. Rev. Lett. 98, 198303 (2007)], where a correspondence was drawn between crossover and percolation of both species, in our 3d study we find that structural crossover is unrelated to percolation.

  11. Time-dependent couplings and crossover length scales in nonequilibrium surface roughening

    NASA Astrophysics Data System (ADS)

    Pradas, Marc; López, Juan M.; Hernández-Machado, A.

    2007-07-01

    We show that time-dependent couplings may lead to nontrivial scaling properties of the surface fluctuations of the asymptotic regime in nonequilibrium kinetic roughening models. Three typical situations are studied. In the case of a crossover between two different rough regimes, the time-dependent coupling may result in anomalous scaling for scales above the crossover length. In a different setting, for a crossover from a rough to either a flat or damping regime, the time-dependent crossover length may conspire to produce a rough surface, although the most relevant term tends to flatten the surface. In addition, our analysis sheds light into an existing debate in the problem of spontaneous imbibition, where time-dependent couplings naturally arise in theoretical models and experiments.

  12. The Misguided Ethics of Crossover Trials

    PubMed Central

    Prasad, Vinay; Grady, Christine

    2014-01-01

    Crossover is increasingly favored in trials of cancer therapies; even those that seek to establish the basic efficacy of novel drugs. Crossover is done in part for trial recruitment, but also out of a sense of doing the right thing—offering the investigational agent to more patients. In this paper, we argue that this ethical feeling—that crossover is a preferred trial choice—is misguided. In seeking to sate the desires of participants, we might undermine a trial’s ability to answer a meaningful clinical question. When a trial is incapable of answering a question, it becomes unethical. Using a crossover strategy in oncology clinical trials can make trials less ethical, not more. L’enfer est plein de bonnes volontés et désirs (Hell is full of good wishes and desires)--Saint Bernard of Clairvaux (c.1150) PMID:24365533

  13. Microelectromechanical systems integrating molecular spin crossover actuators

    NASA Astrophysics Data System (ADS)

    Manrique-Juarez, Maria D.; Rat, Sylvain; Mathieu, Fabrice; Saya, Daisuke; Séguy, Isabelle; Leïchlé, Thierry; Nicu, Liviu; Salmon, Lionel; Molnár, Gábor; Bousseksou, Azzedine

    2016-08-01

    Silicon MEMS cantilevers coated with a 200 nm thin layer of the molecular spin crossover complex [Fe(H2B(pz)2)2(phen)] (H2B(pz)2 = dihydrobis(pyrazolyl)borate and phen = 1,10-phenantroline) were actuated using an external magnetic field and their resonance frequency was tracked by means of integrated piezoresistive detection. The light-induced spin-state switching of the molecules from the ground low spin to the metastable high spin state at 10 K led to a well-reproducible shift of the cantilever's resonance frequency (Δfr = -0.52 Hz). Control experiments at different temperatures using coated as well as uncoated devices along with simple calculations support the assignment of this effect to the spin transition. This latter translates into changes in mechanical behavior of the cantilever due to the strong spin-state/lattice coupling. A guideline for the optimization of device parameters is proposed so as to efficiently harness molecular scale movements for large-scale mechanical work, thus paving the road for nanoelectromechanical systems (NEMS) actuators based on molecular materials.

  14. Standard Model thermodynamics across the electroweak crossover

    NASA Astrophysics Data System (ADS)

    Laine, M.; Meyer, M.

    2015-07-01

    Even though the Standard Model with a Higgs mass mH = 125GeV possesses no bulk phase transition, its thermodynamics still experiences a "soft point" at temperatures around T = 160GeV, with a deviation from ideal gas thermodynamics. Such a deviation may have an effect on precision computations of weakly interacting dark matter relic abundances if their mass is in the few TeV range, or on leptogenesis scenarios operating in this temperature range. By making use of results from lattice simulations based on a dimensionally reduced effective field theory, we estimate the relevant thermodynamic functions across the crossover. The results are tabulated in a numerical form permitting for their insertion as a background equation of state into cosmological particle production/decoupling codes. We find that Higgs dynamics induces a non-trivial "structure" visible e.g. in the heat capacity, but that in general the largest radiative corrections originate from QCD effects, reducing the energy density by a couple of percent from the free value even at T > 160GeV.

  15. Standard Model thermodynamics across the electroweak crossover

    SciTech Connect

    Laine, M.; Meyer, M. E-mail: meyer@itp.unibe.ch

    2015-07-01

    Even though the Standard Model with a Higgs mass m{sub H} = 125GeV possesses no bulk phase transition, its thermodynamics still experiences a 'soft point' at temperatures around T = 160GeV, with a deviation from ideal gas thermodynamics. Such a deviation may have an effect on precision computations of weakly interacting dark matter relic abundances if their mass is in the few TeV range, or on leptogenesis scenarios operating in this temperature range. By making use of results from lattice simulations based on a dimensionally reduced effective field theory, we estimate the relevant thermodynamic functions across the crossover. The results are tabulated in a numerical form permitting for their insertion as a background equation of state into cosmological particle production/decoupling codes. We find that Higgs dynamics induces a non-trivial 'structure' visible e.g. in the heat capacity, but that in general the largest radiative corrections originate from QCD effects, reducing the energy density by a couple of percent from the free value even at T > 160GeV.

  16. Microelectromechanical systems integrating molecular spin crossover actuators

    SciTech Connect

    Manrique-Juarez, Maria D.; Rat, Sylvain; Salmon, Lionel; Molnár, Gábor; Bousseksou, Azzedine E-mail: azzedine.bousseksou@lcc-toulouse.fr; Mathieu, Fabrice; Saya, Daisuke; Séguy, Isabelle; Leïchlé, Thierry; Nicu, Liviu E-mail: azzedine.bousseksou@lcc-toulouse.fr

    2016-08-08

    Silicon MEMS cantilevers coated with a 200 nm thin layer of the molecular spin crossover complex [Fe(H{sub 2}B(pz){sub 2}){sub 2}(phen)] (H{sub 2}B(pz){sub 2} = dihydrobis(pyrazolyl)borate and phen = 1,10-phenantroline) were actuated using an external magnetic field and their resonance frequency was tracked by means of integrated piezoresistive detection. The light-induced spin-state switching of the molecules from the ground low spin to the metastable high spin state at 10 K led to a well-reproducible shift of the cantilever's resonance frequency (Δf{sub r} = −0.52 Hz). Control experiments at different temperatures using coated as well as uncoated devices along with simple calculations support the assignment of this effect to the spin transition. This latter translates into changes in mechanical behavior of the cantilever due to the strong spin-state/lattice coupling. A guideline for the optimization of device parameters is proposed so as to efficiently harness molecular scale movements for large-scale mechanical work, thus paving the road for nanoelectromechanical systems (NEMS) actuators based on molecular materials.

  17. Standard Model thermodynamics across the electroweak crossover

    SciTech Connect

    Laine, M.; Meyer, M.

    2015-07-22

    Even though the Standard Model with a Higgs mass m{sub \\tiny H}=125 GeV possesses no bulk phase transition, its thermodynamics still experiences a “soft point” at temperatures around T=160 GeV, with a deviation from ideal gas thermodynamics. Such a deviation may have an effect on precision computations of weakly interacting dark matter relic abundances if their mass is in the few TeV range, or on leptogenesis scenarios operating in this temperature range. By making use of results from lattice simulations based on a dimensionally reduced effective field theory, we estimate the relevant thermodynamic functions across the crossover. The results are tabulated in a numerical form permitting for their insertion as a background equation of state into cosmological particle production/decoupling codes. We find that Higgs dynamics induces a non-trivial “structure” visible e.g. in the heat capacity, but that in general the largest radiative corrections originate from QCD effects, reducing the energy density by a couple of percent from the free value even at T>160 GeV.

  18. Thermodynamics of Forming a Parallel DNA Crossover

    PubMed Central

    Spink, Charles H.; Ding, Liang; Yang, Qingyi; Sheardy, Richard D.; Seeman, Nadrian C.

    2009-01-01

    Abstract The process of genetic recombination involves the formation of branched four-stranded DNA structures known as Holliday junctions. The Holliday junction is known to have an antiparallel orientation of its helices, i.e., the crossover occurs between strands of opposite polarity. Some intermediates in this process are known to involve two crossover sites, and these may involve crossovers between strands of identical polarity. Surprisingly, if a crossover occurs at every possible juxtaposition of backbones between parallel DNA double helices, the molecules form a paranemic structure with two helical domains, known as PX-DNA. Model PX-DNA molecules can be constructed from a variety of DNA molecules with five nucleotide pairs in the minor groove and six, seven or eight nucleotide pairs in the major groove. A topoisomer of the PX motif is the juxtaposed JX1 molecule, wherein one crossover is missing between the two helical domains. The JX1 molecule offers an outstanding baseline molecule with which to compare the PX molecule, so as to measure the thermodynamic cost of forming a crossover in a parallel molecule. We have made these measurements using calorimetric and ultraviolet hypochromicity methods, as well as denaturing gradient gel electrophoretic methods. The results suggest that in relaxed conditions, a system that meets the pairing requirements for PX-DNA would prefer to form the PX motif relative to juxtaposed molecules, particularly for the 6:5 structure. PMID:19619467

  19. Design, analysis, and presentation of crossover trials

    PubMed Central

    Mills, Edward J; Chan, An-Wen; Wu, Ping; Vail, Andy; Guyatt, Gordon H; Altman, Douglas G

    2009-01-01

    Objective Although crossover trials enjoy wide use, standards for analysis and reporting have not been established. We reviewed methodological aspects and quality of reporting in a representative sample of published crossover trials. Methods We searched MEDLINE for December 2000 and identified all randomized crossover trials. We abstracted data independently, in duplicate, on 14 design criteria, 13 analysis criteria, and 14 criteria assessing the data presentation. Results We identified 526 randomized controlled trials, of which 116 were crossover trials. Trials were drug efficacy (48%), pharmacokinetic (28%), and nonpharmacologic (30%). The median sample size was 15 (interquartile range 8–38). Most (72%) trials used 2 treatments and had 2 periods (64%). Few trials reported allocation concealment (17%) or sequence generation (7%). Only 20% of trials reported a sample size calculation and only 31% of these considered pairing of data in the calculation. Carry-over issues were addressed in 29% of trial's methods. Most trials reported and defended a washout period (70%). Almost all trials (93%) tested for treatment effects using paired data and also presented details on by-group results (95%). Only 29% presented CIs or SE so that data could be entered into a meta-analysis. Conclusion Reports of crossover trials frequently omit important methodological issues in design, analysis, and presentation. Guidelines for the conduct and reporting of crossover trials might improve the conduct and reporting of studies using this important trial design. PMID:19405975

  20. Behavioral testing of antidepressant compounds: an analysis of crossover design for correlated binary data.

    PubMed

    Shkedy, Ziv; Vandersmissen, Veerle; Molenberghs, Geert; Van Craenendonck, Hansfried; Aerts, Nancy; Steckler, Thomas; Bijnens, Luc

    2005-06-01

    The differential reinforcement of low-rate 72 seconds schedule (DRL-72) is a standard behavioral test procedure for screening potential antidepressant compounds. The protocol for the DRL-72 experiment, proposed by Evenden et al. (1993), consists of using a crossover design for the experiment and one-way ANOVA for the statistical analysis. In this paper we discuss the choice of several crossover designs for the DRL-72 experiment and propose to estimate the treatment effects using either generalized linear mixed models (GLMM) or generalized estimating equation (GEE) models for clustered binary data.

  1. Bullen's parameter as a seismic observable for spin crossovers in the lower mantle

    NASA Astrophysics Data System (ADS)

    Valencia-Cardona, J. J.; Da Silveira, P. R.; Williams, Q.; Wentzcovitch, R. M.

    2016-12-01

    Elastic anomalies produced by the spin crossover in ferropericlase have been documented by both first principles calculations and high pressure-temperature experiments. The predicted signature of this spin crossover in the lower mantle is subtle and not obvious. Thermally induced velocity heterogeneities associated with this crossover appear to correlate statistically with seismic tomography patterns observed in deeply rooted plumes (1), however, spherically averaged anomalies have not yet been recognized by seismologic studies of the deep mantle. This may be due to the resolving capabilities for gradual changes in seismic velocities and the complicated data processing techniques and trade-offs involved in seismic inversions of depth-dependent velocity and density structures. In particular, velocity anomalies associated with the spin crossover in ferropericlase span a depth range greater than 1,000 km at mantle temperatures. A sensitive seismic parameter is needed to determine the presence or absence of this spin crossover signature and shed light on the amount of ferropericlase in the lower mantle. Bullen's parameter, η, is an ideal candidate as it relates seismic wave speeds with density variations, and sensitively records deviations from adiabaticity. For the lower mantle, values of η close to 1 are typically derived in 1-D models, with greater values implying superadiabatic gradients. Here we address the behavior of this parameter for different lower mantle compositions as they undergo the spin crossover. We conclude that predicted deviations in Bullen's parameter due to the spin crossover in ferropericlase for geophysically relevant compositions may be sufficiently large to turn up in accurate seismic inversions of this parameter. (1) Z.-Q. Wu and R. Wentzcovitch, Spin crossover in ferropericlase and lateral heterogeneities in the Earth's lower mantle, Proc. Nat. Acad. Sc. USA 111, 10468- 10472 (2014).

  2. Spin-crossover molecule based thermoelectric junction

    SciTech Connect

    Ghosh, Dibyajyoti; Parida, Prakash; Pati, Swapan K.

    2015-05-11

    Using ab-initio numerical methods, we explore the spin-dependent transport and thermoelectric properties of a spin-crossover molecule (i.e., iron complex of 2-(1H-pyrazol-1-yl)-6-(1H-tetrazole-5-yl)pyridine) based nano-junction. We demonstrate a large magnetoresistance, efficient conductance-switching, and spin-filter activity in this molecule-based two-terminal device. The spin-crossover process also modulates the thermoelectric entities. It can efficiently switch the magnitude as well as spin-polarization of the thermocurrent. We find that thermocurrent is changed by ∼4 orders of magnitude upon spin-crossover. Moreover, it also substantially affects the thermopower and consequently, the device shows extremely efficient spin-crossover magnetothermopower generation. Furthermore, by tuning the chemical potential of electrodes into a certain range, a pure spin-thermopower can be achieved for the high-spin state. Finally, the reasonably large values of figure-of-merit in the presence and absence of phonon demonstrate a large heat-to-voltage conversion efficiency of the device. We believe that our study will pave an alternative way of tuning the transport and thermoelectric properties through the spin-crossover process and can have potential applications in generation of spin-dependent current, information storage, and processing.

  3. Looking forwards and backwards: The real-time processing of Strong and Weak Crossover.

    PubMed

    Kush, Dave; Lidz, Jeffrey; Phillips, Colin

    2017-01-01

    We investigated the processing of pronouns in Strong and Weak Crossover constructions as a means of probing the extent to which the incremental parser can use syntactic information to guide antecedent retrieval. In Experiment 1 we show that the parser accesses a displaced wh-phrase as an antecedent for a pronoun when no grammatical constraints prohibit binding, but the parser ignores the same wh-phrase when it stands in a Strong Crossover relation to the pronoun. These results are consistent with two possibilities. First, the parser could apply Principle C at antecedent retrieval to exclude the wh-phrase on the basis of the c-command relation between its gap and the pronoun. Alternatively, retrieval might ignore any phrases that do not occupy an Argument position. Experiment 2 distinguished between these two possibilities by testing antecedent retrieval under Weak Crossover. In Weak Crossover binding of the pronoun is ruled out by the argument condition, but not Principle C. The results of Experiment 2 indicate that antecedent retrieval accesses matching wh-phrases in Weak Crossover configurations. On the basis of these findings we conclude that the parser can make rapid use of Principle C and c-command information to constrain retrieval. We discuss how our results support a view of antecedent retrieval that integrates inferences made over unseen syntactic structure into constraints on backward-looking processes like memory retrieval.

  4. Looking forwards and backwards: The real-time processing of Strong and Weak Crossover

    PubMed Central

    Lidz, Jeffrey; Phillips, Colin

    2017-01-01

    We investigated the processing of pronouns in Strong and Weak Crossover constructions as a means of probing the extent to which the incremental parser can use syntactic information to guide antecedent retrieval. In Experiment 1 we show that the parser accesses a displaced wh-phrase as an antecedent for a pronoun when no grammatical constraints prohibit binding, but the parser ignores the same wh-phrase when it stands in a Strong Crossover relation to the pronoun. These results are consistent with two possibilities. First, the parser could apply Principle C at antecedent retrieval to exclude the wh-phrase on the basis of the c-command relation between its gap and the pronoun. Alternatively, retrieval might ignore any phrases that do not occupy an Argument position. Experiment 2 distinguished between these two possibilities by testing antecedent retrieval under Weak Crossover. In Weak Crossover binding of the pronoun is ruled out by the argument condition, but not Principle C. The results of Experiment 2 indicate that antecedent retrieval accesses matching wh-phrases in Weak Crossover configurations. On the basis of these findings we conclude that the parser can make rapid use of Principle C and c-command information to constrain retrieval. We discuss how our results support a view of antecedent retrieval that integrates inferences made over unseen syntactic structure into constraints on backward-looking processes like memory retrieval. PMID:28936483

  5. Multiferroic crossover in perovskite oxides

    NASA Astrophysics Data System (ADS)

    Weston, L.; Cui, X. Y.; Ringer, S. P.; Stampfl, C.

    2016-04-01

    drives the ferroelectric state (Kv). The recovery of the lattice instability for high-spin d5-d7 and d8 cations is due to (i) a reduction in K0 due to a significant volume increase arising from population of the σ -bonded axial d eg orbitals, and (ii) an increase in the Kv contribution arising from increased p -d hybridization; our calculations suggest that the former mechanism is dominant. Surprisingly, we are able to show that, in some cases unpaired electron spins actually drive ferroelectricity, rather than inhibit it, which represents a shift in the understanding of how ferroelectricity and magnetism interact in perovskite oxides. It follows, that for the case of BiCoO3, the Co3 + ion plays a major role in the ferroelectric lattice instability. Importantly, the ferroelectric polarization is greatly enhanced when the Co3 + ion is in the high-spin state, when compared to the nonmagnetic, low-spin state, and a large coupling of the electric and magnetic polarization is present. Generally, for d5-d7 B cations in A B O3 perovskites, an inherent and remarkably strong magnetoelectric coupling exists via the multiferroic crossover effect, whereby switching the spin state strongly affects the ferroelectric polarization and, potentially, manipulation of the polarization with an externally applied electric field could induce a spin-state transition. This novel effect is demonstrated for BiCoO3, for which the ground spin state is switched by reducing the internal ferroelectric polarization. These results provide a deeper insight into perovskite ferroelectrics and multiferroics.

  6. Crossover and scaling phenomena in a disordered Fermi liquid

    NASA Astrophysics Data System (ADS)

    Belitz, D.; Kirkpatrick, T. R.

    1989-09-01

    We consider Finkelshtein's model for a disordered Fermi liquid. We show that logarithmic terms at two-loop order suppress the fixed point proposed by Castellani et al. Spin transport slows down dramatically, and in d=2+ɛ a sizable scaling region exists. We show that in the scaling region the apparent conductivity exponent is zero to all orders in a loop expansion. This implies that the charge transport is unaffected by the crossover in the spin system. Experiments compare favorably with this scenario. Further measurements of the Wilson ratio are proposed.

  7. Fluctuations of the number of particles within a given volume in cold quantum gases

    SciTech Connect

    Astrakharchik, G. E.; Combescot, R.; Pitaevskii, L. P.

    2007-12-15

    In ultracold gases many experiments use atom imaging as a basic observable. The resulting image is averaged over a number of realizations and mostly only this average is used. Only recently the noise has been measured to extract physical information. In the present paper we investigate the quantum noise arising in these gases at zero temperature. We restrict ourselves to the homogeneous situation and study the fluctuations in particle number found within a given volume in the gas, and more specifically inside a sphere of radius R. We show that zero-temperature fluctuations are not extensive and the leading term scales with sphere radius R as R{sup 2} ln R (or ln R) in three- (or one-) dimensional systems. We calculate systematically the next term beyond this leading order. We consider first the generic case of a compressible superfluid. Then we investigate the whole Bose-Einstein-condensation (BEC) -BCS crossover, and in particular the limiting cases of the weakly interacting Bose gas and of the free Fermi gas.

  8. Spectral functions in ultracold Fermi gases

    NASA Astrophysics Data System (ADS)

    Schneider, William; Randeria, Mohit

    2011-03-01

    We study the fermion spectral function in the superfluid state across the BEC-BCS crossover and in the normal Fermi liquid phase in highly imbalanced Fermi gases. We focus on features that can be measured in momentum-resolved radio frequency spectroscopy experiments. We go beyond mean field theory and include the effects of Gaussian order parameter fluctuations in a manner that gives excellent agreement with asymptotically exact results for the T = 0 equation of state in the BEC and BCS limits, as well as quantum Monte Carlo (QMC) results near unitarity. We show that sharp Bogoliubov quasiparticles, with a substantial coherent spectral weight, exist near unitarity. We argue that this is true generally even beyond the Gaussian approximation. In addition, quasiparticle scattering and interaction with collective modes produces incoherent spectral weight. We show that the dispersion is strongly renormalized at unitarity with its minimum shifted up from its mean field value √{ 2 mμ } and compare our results with existing QMC data. We discuss how the spectral function changes qualitatively compared with its mean field form as 1 / (kF a) increases and the chemical potential changes sign. Supported by NSF-DMR 0706203 and ARO W911NF-08-1-0338.

  9. Magnetic crossover realized by electrical methods

    NASA Astrophysics Data System (ADS)

    Hao, Hua; Zheng, XiaoHong; Jia, Ting; Zeng, Zhi

    2017-05-01

    Electrical control of molecular-scale magnetisms is a greatly important topic in molecular spintronics. This enables the ultimate-limit manipulation of magnetisms, and has the potential to revolutionize computer technologies. Two mechanisms related to electrical control of molecular-scale magnetisms are concerned in this review. One is the magnetic crossover realized by the electrostatic Stark effect. The other is the magnetic crossover induced by the electron tunneling through the lowest unoccupied molecular orbital under bias voltages or one added electron under gate voltages.

  10. Anode reaction mechanism and crossover in direct dimethyl ether fuel cell

    NASA Astrophysics Data System (ADS)

    Mizutani, Itsuko; Liu, Yan; Mitsushima, Shigenori; Ota, Ken-ichiro; Kamiya, Nobuyuki

    The anode reaction mechanism and the crossover of a direct dimethyl ether fuel cell (DDMEFC) have been investigated. This was done by considering the anode products of the half-cell and DDMEFC experiments. It was found that the CO 2 current efficiency of the DDMEFC was almost 1 at 30-80 °C and that this value was higher than that of a DMFC. The main by-products of the DDMEFC were methyl formate and methanol whose amounts are negligibly small compared to CO 2. With respect to crossover, the influence of DME on the oxygen reduction reaction (ORR) was examined with a half-cell, and the amount of crossover of DME was measured while operating an actually constructed DDMEFC. From these experiments, it was found that DME does not influence the ORR as much as methanol under similar conditions. Furthermore, the amount of crossover of DME decreased with an increase in temperature and current density and it was one-half that of methanol on open circuit and at 80 °C. The CO 2 current efficiency of the DDMEFC is higher than that of a DMFC, and the influence of crossover in the DDMEFC is less than that in the DMFC. Since the temperature dependence of the reactivity of DME is larger than that of methanol, the higher output is expected for the DDMEFC at the elevated temperature. Therefore, the DDMEFC has a promising potential as a portable power source in the future.

  11. The Design of Cluster Randomized Crossover Trials

    ERIC Educational Resources Information Center

    Rietbergen, Charlotte; Moerbeek, Mirjam

    2011-01-01

    The inefficiency induced by between-cluster variation in cluster randomized (CR) trials can be reduced by implementing a crossover (CO) design. In a simple CO trial, each subject receives each treatment in random order. A powerful characteristic of this design is that each subject serves as its own control. In a CR CO trial, clusters of subjects…

  12. The Design of Cluster Randomized Crossover Trials

    ERIC Educational Resources Information Center

    Rietbergen, Charlotte; Moerbeek, Mirjam

    2011-01-01

    The inefficiency induced by between-cluster variation in cluster randomized (CR) trials can be reduced by implementing a crossover (CO) design. In a simple CO trial, each subject receives each treatment in random order. A powerful characteristic of this design is that each subject serves as its own control. In a CR CO trial, clusters of subjects…

  13. Critical Crossover Functions for Simple Fluids: Towards the Crossover Modelling Uniqueness

    NASA Astrophysics Data System (ADS)

    Garrabos, Yves; Lecoutre, Carole; Marre, Samuel; LeNeindre, Bernard; Hahn, Inseob

    2016-11-01

    Based on a single non-universal temperature scaling factor present in a simple fluid case, a detailed analysis of non-universal parameters involved in different critical-to-classical crossover models is given. For the infinite limit of the cutoff wave number, a set of three scaling-parameters is defined for each model such that it shows all the shapes of the theoretical crossover functions overlap on the mean crossover function shapes close to the non-trivial fixed point. The analysis of corresponding links between their fluid-dependent parameters opens a route to define a parametric model of crossover equation-of-state, closely satisfying the universal features calculated from the Ising-like limit in the massive renormalization scheme.

  14. Extensive Interallelic Polymorphisms Drive Meiotic Recombination into a Crossover Pathway

    PubMed Central

    Dooner, Hugo K.

    2002-01-01

    Recombinants isolated from most meiotic intragenic recombination experiments in maize, but not in yeast, are borne principally on crossover chromosomes. This excess of crossovers is not explained readily by the canonical double-strand break repair model of recombination, proposed to account for a large body of yeast data, which predicts that crossovers (COs) and noncrossovers (NCOs) should be recovered equally. An attempt has been made here to identify general rules governing the recovery of the CO and NCO classes of intragenic recombinants in maize. Recombination was analyzed in bz heterozygotes between a variety of mutations derived from the same or different progenitor alleles. The mutations include point mutations, transposon insertions, and transposon excision footprints. Consequently, the differences between the bz heteroalleles ranged from just two nucleotides to many nucleotides, indels, and insertions. In this article, allelic pairs differing at only two positions are referred to as dimorphic to distinguish them from polymorphic pairs, which differ at multiple positions. The present study has revealed the following effects at these bz heteroalleles: (1) recombination between polymorphic heteroalleles produces mostly CO chromosomes; (2) recombination between dimorphic heteroalleles produces both CO and NCO chromosomes, in ratios apparently dependent on the nature of the heteroalleles; and (3) in dimorphic heterozygotes, the two NCO classes are recovered in approximately equal numbers when the two mutations are point mutations but not when one or both mutations are insertions. These observations are discussed in light of a recent version of the double-strand break repair model of recombination that postulates separate pathways for the formation of CO and NCO products. PMID:12034905

  15. Spectrum and Dynamics of the BCS-BEC Crossover from a Few-Body Perspective

    SciTech Connect

    Stecher, Javier von; Greene, Chris H.

    2007-08-31

    The spectrum of two spin-up and two spin-down fermions in a trap is calculated using a correlated Gaussian basis throughout the range of the BCS-BEC crossover. These accurate calculations provide a few-body solution to the crossover problem. This solution is used to study the time evolution of the system as the scattering length is changed, mimicking experiments with Fermi gases near Fano-Feshbach resonances. The structure of avoiding crossings in the spectrum allow us to understand the dynamics of the system as a sequence of Landau-Zener transitions. Finally, we propose a ramping scheme to study atom-molecule coherence.

  16. Spin crossover and hyperfine interactions of iron in (Mg ,Fe ) CO3 ferromagnesite

    NASA Astrophysics Data System (ADS)

    Hsu, Han; Huang, Sheng-Chieh

    2016-08-01

    Ferromagnesite, an iron-bearing carbonate stable up to 100-115 GPa, is believed to be the major carbon carrier in the earth's lower mantle and play a key role in the earth's deep carbon cycle. In this paper, we use the local density approximation plus self-consistent Hubbard U (LDA+Usc) method to study the iron spin crossover in ferromagnesite with a wide range of iron concentration (12.5-100%). Our calculation shows that this mineral undergoes a crossover from the high-spin (HS) (S =2 ) to the low-spin (LS) (S =0 ) state at around 45-50 GPa, regardless of the iron concentration. The intermediate-spin (S =1 ) state is energetically unfavorable and not involved in spin crossover. The anomalous changes of volume, density, and bulk modulus accompanying the spin crossover obtained in our calculation are in great agreement with experiments. Our calculation also predicts that an abrupt change of the iron nuclear quadrupole splitting, from ≳2.8 mm/s to ≲0.3 mm/s, can be observed in Mössbauer spectra at 45-50 GPa as a signature of the HS-LS crossover.

  17. Threshold Levels of Infant and Under-Five Mortality for Crossover between Life Expectancies at Ages Zero, One and Five in India: A Decomposition Analysis.

    PubMed

    Dubey, Manisha; Ram, Usha; Ram, Faujdar

    2015-01-01

    Under the prevailing conditions of imbalanced life table and historic gender discrimination in India, our study examines crossover between life expectancies at ages zero, one and five years for India and quantifies the relative share of infant and under-five mortality towards this crossover. We estimate threshold levels of infant and under-five mortality required for crossover using age specific death rates during 1981-2009 for 16 Indian states by sex (comprising of India's 90% population in 2011). Kitagawa decomposition equations were used to analyse relative share of infant and under-five mortality towards crossover. India experienced crossover between life expectancies at ages zero and five in 2004 for menand in 2009 for women; eleven and nine Indian states have experienced this crossover for men and women, respectively. Men usually experienced crossover four years earlier than the women. Improvements in mortality below ages five have mostly contributed towards this crossover. Life expectancy at age one exceeds that at age zero for both men and women in India except for Kerala (the only state to experience this crossover in 2000 for men and 1999 for women). For India, using life expectancy at age zero and under-five mortality rate together may be more meaningful to measure overall health of its people until the crossover. Delayed crossover for women, despite higher life expectancy at birth than for men reiterates that Indian women are still disadvantaged and hence use of life expectancies at ages zero, one and five become important for India. Greater programmatic efforts to control leading causes of death during the first month and 1-59 months in high child mortality areas can help India to attain this crossover early.

  18. Threshold Levels of Infant and Under-Five Mortality for Crossover between Life Expectancies at Ages Zero, One and Five in India: A Decomposition Analysis

    PubMed Central

    Dubey, Manisha

    2015-01-01

    Objectives Under the prevailing conditions of imbalanced life table and historic gender discrimination in India, our study examines crossover between life expectancies at ages zero, one and five years for India and quantifies the relative share of infant and under-five mortality towards this crossover. Methods We estimate threshold levels of infant and under-five mortality required for crossover using age specific death rates during 1981–2009 for 16 Indian states by sex (comprising of India’s 90% population in 2011). Kitagawa decomposition equations were used to analyse relative share of infant and under-five mortality towards crossover. Findings India experienced crossover between life expectancies at ages zero and five in 2004 for menand in 2009 for women; eleven and nine Indian states have experienced this crossover for men and women, respectively. Men usually experienced crossover four years earlier than the women. Improvements in mortality below ages five have mostly contributed towards this crossover. Life expectancy at age one exceeds that at age zero for both men and women in India except for Kerala (the only state to experience this crossover in 2000 for men and 1999 for women). Conclusions For India, using life expectancy at age zero and under-five mortality rate together may be more meaningful to measure overall health of its people until the crossover. Delayed crossover for women, despite higher life expectancy at birth than for men reiterates that Indian women are still disadvantaged and hence use of life expectancies at ages zero, one and five become important for India. Greater programmatic efforts to control leading causes of death during the first month and 1–59 months in high child mortality areas can help India to attain this crossover early. PMID:26683617

  19. Crossover by Line Length and Spatial Location

    PubMed Central

    Mennemeier, Mark; Rapcsak, Steven Z.; Pierce, Chris; Vezey, Elsie

    2015-01-01

    It is well known that line length has a systematic influence on line bisection error in neglect. Most patients with neglect misbisect long lines on the same side of true center as their brain lesion but then cross over on short lines, misbisecting them on the opposite side (i.e., crossover by line length). What is less recognized is that the spatial location of lines relative to the viewer can similarly induce a crossover effect when one considers line bisection error scores that have been averaged across individual line lengths. Patients with right hemisphere injury and neglect classically make averaged line bisection errors that fall right of true center on lines located either at midline or to the left of the viewer; however, we observed that the averaged line bisection error can fall left of true center when lines are located to the right of the viewer (i.e., crossover by spatial location). We hypothesized that crossover by both line length and spatial location stem from systematic errors in magnitude estimation, i.e., perceived line length. We tested predictions based on this hypothesis by examining how the crossover effect by line length is altered by the spatial location of lines along a horizontal axis relative to the viewer. Participants included patients with unilateral lesions of the right and left cerebral hemispheres and age-appropriate normal subjects. All groups demonstrated a crossover effect by line length at the midline location but the effect was altered by placing lines to the right and left of the viewer. In particular, patients with right hemisphere injury and neglect crossed-over across a hroader range of line lengths when the lines were located to the right of the viewer rather than at either midline or left of the viewer. It is proposed that mental representations of stimulus magnitude are altered in neglect, in addition to mental representations of space, and that traditional accounts of neglect can be enhanced by including the

  20. Universal low-temperature crossover in two-channel Kondo models

    NASA Astrophysics Data System (ADS)

    Mitchell, Andrew K.; Sela, Eran

    2012-06-01

    An exact expression is derived for the electron Green function in two-channel Kondo models with one and two impurities, describing the crossover from non-Fermi liquid (NFL) behavior at intermediate temperatures to standard Fermi liquid (FL) physics at low temperatures. Symmetry-breaking perturbations generically present in experiment ensure the standard low-energy FL description, but the full crossover is wholly characteristic of the unstable NFL state. Distinctive conductance lineshapes in quantum dot devices should result. We exploit a connection between this crossover and one occurring in a classical boundary Ising model to calculate real-space electron densities at finite temperature. The single universal finite-temperature Green function is then extracted by inverting the integral transformation relating these Friedel oscillations to the t matrix. Excellent agreement is demonstrated between exact results and full numerical renormalization group calculations.

  1. Crossover in the Scaling Behavior of Ion-sputtered Pd(001)

    NASA Astrophysics Data System (ADS)

    Kim, T. C.; Kim, Y.; Noh, D. Y.; Kahng, B.; Kim, J.-S.

    2007-01-01

    We investigate morphological evolution of Ar+ ion sputtered Pd(001) by in situ real-time x-ray reflectivity and grazing incidence small angle x-ray scattering (GISAXS) experiments. Surface roughness W, and its dynamic scaling behavior show a definite crossover across a crossover time tc. Before tc, growth exponent β, varies from 0.20 to 0.49 depending on substrate temperature, T. After tc, β drops to ˜0.1, irrespective to substrate temperature. Satellite peaks in GISAXS indicating laterally ordered structure develop as the growth time approaches tc, which become clear with further sputtering. We think that the crossover behavior near tc indicates the reduction of non-linear effect and the scaling behavior would follow the Edwards-Wilkinson model.

  2. Dimensional crossover in fluids under nanometer-scale confinement.

    PubMed

    Das, Amit; Chakrabarti, J

    2012-05-01

    Several earlier studies have shown signatures of crossover in various static and dynamics properties of a confined fluid when the confining dimension decreases to about a nanometer. The density fluctuations govern the majority of such properties of a fluid. Here, we illustrate the crossover in density fluctuation in a confined fluid, to provide a generic understanding of confinement-induced crossover of fluid properties, using computer simulations. The crossover can be understood as a manifestation of changes in the long-wavelength behavior of fluctuation in density due to geometrical constraints. We further show that the confining potential significantly affects the crossover behavior.

  3. High-temperature atomic superfluidity in lattice Bose-Fermi mixtures.

    PubMed

    Illuminati, Fabrizio; Albus, Alexander

    2004-08-27

    We consider atomic Bose-Fermi mixtures in optical lattices and study the superfluidity of fermionic atoms due to s-wave pairing induced by boson-fermion interactions. We prove that the induced fermion-fermion coupling is always attractive if the boson-boson on-site interaction is repulsive, and predict the existence of an enhanced BEC-BCS crossover as the strength of the lattice potential is varied. We show that for direct on-site fermion-fermion repulsion, the induced attraction can give rise to superfluidity via s-wave pairing at striking variance with the case of pure systems of fermionic atoms with direct repulsive interactions.

  4. Acoustic Attenuation Probe for Fermion Superfluidity in Ultracold-Atom Gases

    SciTech Connect

    Gaudio, Sergio; Mihaila, Bogdan; Blagoev, Krastan B.; Timmermans, Eddy; Bedell, Kevin S.

    2007-03-16

    Dilute gas Bose-Einstein condensates (BEC's), currently used to cool fermionic atoms in atom traps, can also probe the superfluidity of these fermions. The damping rate of BEC-acoustic excitations (phonon modes), measured in the middle of the trap as a function of the phonon momentum, yields an unambiguous signature of BCS-like superfluidity, provides a measurement of the superfluid gap parameter, and gives an estimate of the size of the Cooper pairs in the BEC-BCS crossover regime. We also predict kinks in the momentum dependence of the damping rate which can reveal detailed information about the fermion quasiparticle dispersion relation.

  5. Probing quasiparticle states in strongly interacting atomic gases by momentum-resolved Raman photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Dao, Tung-Lam; Carusotto, Iacopo; Georges, Antoine

    2009-08-01

    We investigate a momentum-resolved Raman spectroscopy technique which is able to probe the one-body spectral function and the quasiparticle states of a gas of strongly interacting ultracold atoms. This technique is inspired by angle-resolved photoemission spectroscopy, a powerful experimental probe of electronic states in solid-state systems. Quantitative examples of experimentally accessible spectra are given for the most significant regimes along the BEC-BCS crossover. When the theory is specialized to rf spectroscopy, agreement is found with recent experimental data. The main advantages of this Raman spectroscopy over existing techniques are pointed out.

  6. Exchangeability in the case-crossover design.

    PubMed

    Mittleman, Murray A; Mostofsky, Elizabeth

    2014-10-01

    In cohort and case-control studies, confounding that arises as a result of differences in the distribution of determinants of the outcome between exposure groups leading to non-exchangeability are addressed by restriction, matching or with statistical models. In case-only studies, this issue is addressed by comparing each individual with his/herself. Although case-only designs use self-matching and only include individuals who develop the outcome of interest, issues of non-exchangeability are identical to those that arise in traditional case-control and cohort studies. In this review, we describe one type of case-only design, the case-crossover design, and discuss how the concept of exchangeability can be used to understand issues of confounding, carryover effects, period effects and selection bias in case-crossover studies.

  7. Dimensional crossover in dipolar magnetic layers

    NASA Astrophysics Data System (ADS)

    Bulenda, M.; Täuber, U. C.; Schwabl, F.

    2000-01-01

    We investigate the static critical behaviour of a uniaxial magnetic layer, with finite thickness L in one direction, yet infinitely extended in the remaining d dimensions. The magnetic dipole-dipole interaction is taken into account. We apply a variant of Wilson's momentum shell renormalization group approach to describe the crossover between the critical behaviour of the 3D Ising, 2D Ising, 3D uniaxial dipolar, and the 2D uniaxial dipolar universality classes. The corresponding renormalization group fixed points are in addition to different effective dimensionalities characterized by distinct analytic structures of the propagator, and are consequently associated with varying upper critical dimensions. While the limiting cases can be discussed by means of dimensional icons/Journals/Common/epsilon" ALT="epsilon" ALIGN="TOP"/> expansions with respect to the appropriate upper critical dimensions, respectively, the crossover features must be addressed in terms of the renormalization group flow trajectories at fixed dimensionality d .

  8. Crossover from quantum to classical transport

    NASA Astrophysics Data System (ADS)

    Morr, Dirk K.

    2016-01-01

    Understanding the crossover from quantum to classical transport has become of fundamental importance not only for technological applications due to the creation of sub-10-nm transistors - an important building block of our modern life - but also for elucidating the role played by quantum mechanics in the evolutionary fitness of biological complexes. This article provides a basic introduction into the nature of charge and energy transport in the quantum and classical regimes. It discusses the characteristic transport properties in both limits and demonstrates how they can be connected through the loss of quantum mechanical coherence. The salient features of the crossover physics are identified, and their importance in opening new transport regimes and in understanding efficient and robust energy transport in biological complexes are demonstrated.

  9. Viscous to Inertial Crossover in Liquid Drop Coalescence

    NASA Astrophysics Data System (ADS)

    Paulsen, Joseph; Burton, Justin; Nagel, Sidney

    2010-11-01

    When two liquid drops coalesce, a dramatic topological transition occurs. We use an electrical method and high-speed imaging to probe the coalescence down to 10 ns after the drops touch. Immediately after contact, the resistance varies as t-1 and later crosses over to t-1/2. In the case of water drops [1], this behavior had been interpreted with a model in which coalescence occurs between slightly deformed interfaces. By varying the liquid viscosity over two decades, we conclude that at sufficiently low approach velocity where deformation is not present, the drops coalesce as spheres, but with an unexpectedly late crossover time between a regime dominated by viscous (i.e., t-1) and one dominated by inertial (i.e., t-1/2) effects. This interpretation is consistent with experiments in which we change the drop approach velocity and the surrounding gas pressure and molecular weight. We argue that the late crossover, not accounted for in the theory [2], is due to the flow field in the liquid and an additional length-scale present in the drop geometry. [1] S. C. Case, and S. R. Nagel, PRL 100, 084503 (2008). [2] J. Eggers, J. Lister, and H. A. Stone, JFM 401, 293 (1999).

  10. More than one dynamic crossover in protein hydration water

    PubMed Central

    Mazza, Marco G.; Stokely, Kevin; Pagnotta, Sara E.; Bruni, Fabio; Stanley, H. Eugene; Franzese, Giancarlo

    2011-01-01

    Studies of liquid water in its supercooled region have helped us better understand the structure and behavior of water. Bulk water freezes at its homogeneous nucleation temperature (approximately 235 K), but protein hydration water avoids this crystallization because each water molecule binds to a protein. Here, we study the dynamics of the hydrogen bond (HB) network of a percolating layer of water molecules and compare the measurements of a hydrated globular protein with the results of a coarse-grained model that successfully reproduces the properties of hydration water. Using dielectric spectroscopy, we measure the temperature dependence of the relaxation time of proton charge fluctuations. These fluctuations are associated with the dynamics of the HB network of water molecules adsorbed on the protein surface. Using Monte Carlo simulations and mean-field calculations, we study the dynamics and thermodynamics of the model. Both experimental and model analyses are consistent with the interesting possibility of two dynamic crossovers, (i) at approximately 252 K and (ii) at approximately 181 K. Because the experiments agree with the model, we can relate the two crossovers to the presence at ambient pressure of two specific heat maxima. The first is caused by fluctuations in the HB formation, and the second, at a lower temperature, is due to the cooperative reordering of the HB network. PMID:22135473

  11. More than one dynamic crossover in protein hydration water.

    PubMed

    Mazza, Marco G; Stokely, Kevin; Pagnotta, Sara E; Bruni, Fabio; Stanley, H Eugene; Franzese, Giancarlo

    2011-12-13

    Studies of liquid water in its supercooled region have helped us better understand the structure and behavior of water. Bulk water freezes at its homogeneous nucleation temperature (approximately 235 K), but protein hydration water avoids this crystallization because each water molecule binds to a protein. Here, we study the dynamics of the hydrogen bond (HB) network of a percolating layer of water molecules and compare the measurements of a hydrated globular protein with the results of a coarse-grained model that successfully reproduces the properties of hydration water. Using dielectric spectroscopy, we measure the temperature dependence of the relaxation time of proton charge fluctuations. These fluctuations are associated with the dynamics of the HB network of water molecules adsorbed on the protein surface. Using Monte Carlo simulations and mean-field calculations, we study the dynamics and thermodynamics of the model. Both experimental and model analyses are consistent with the interesting possibility of two dynamic crossovers, (i) at approximately 252 K and (ii) at approximately 181 K. Because the experiments agree with the model, we can relate the two crossovers to the presence at ambient pressure of two specific heat maxima. The first is caused by fluctuations in the HB formation, and the second, at a lower temperature, is due to the cooperative reordering of the HB network.

  12. JavaGenes: Evolving Graphs with Crossover

    NASA Technical Reports Server (NTRS)

    Globus, Al; Atsatt, Sean; Lawton, John; Wipke, Todd

    2000-01-01

    Genetic algorithms usually use string or tree representations. We have developed a novel crossover operator for a directed and undirected graph representation, and used this operator to evolve molecules and circuits. Unlike strings or trees, a single point in the representation cannot divide every possible graph into two parts, because graphs may contain cycles. Thus, the crossover operator is non-trivial. A steady-state, tournament selection genetic algorithm code (JavaGenes) was written to implement and test the graph crossover operator. All runs were executed by cycle-scavagging on networked workstations using the Condor batch processing system. The JavaGenes code has evolved pharmaceutical drug molecules and simple digital circuits. Results to date suggest that JavaGenes can evolve moderate sized drug molecules and very small circuits in reasonable time. The algorithm has greater difficulty with somewhat larger circuits, suggesting that directed graphs (circuits) are more difficult to evolve than undirected graphs (molecules), although necessary differences in the crossover operator may also explain the results. In principle, JavaGenes should be able to evolve other graph-representable systems, such as transportation networks, metabolic pathways, and computer networks. However, large graphs evolve significantly slower than smaller graphs, presumably because the space-of-all-graphs explodes combinatorially with graph size. Since the representation strongly affects genetic algorithm performance, adding graphs to the evolutionary programmer's bag-of-tricks should be beneficial. Also, since graph evolution operates directly on the phenotype, the genotype-phenotype translation step, common in genetic algorithm work, is eliminated.

  13. Quantum-classical crossover in electrodynamics

    SciTech Connect

    Polonyi, Janos

    2006-09-15

    A classical field theory is proposed for the electric current and the electromagnetic field interpolating between microscopic and macroscopic domains. It represents a generalization of the density functional for the dynamics of the current and the electromagnetic field in the quantum side of the crossover and reproduces standard classical electrodynamics on the other side. The effective action derived in the closed time path formalism and the equations of motion follow from the variational principle. The polarization of the Dirac-sea can be taken into account in the quadratic approximation of the action by the introduction of the deplacement field strengths as in conventional classical electrodynamics. Decoherence appears naturally as a simple one-loop effect in this formalism. It is argued that the radiation time arrow is generated from the quantum boundary conditions in time by decoherence at the quantum-classical crossover and the Abraham-Lorentz force arises from the accelerating charge or from other charges in the macroscopic or the microscopic side, respectively. The functional form of the quantum renormalization group, the generalization of the renormalization group method for the density matrix, is proposed to follow the scale dependence through the quantum-classical crossover in a systematical manner.

  14. Geosat crossover analysis in the tropical Pacific. Part 1: Constrained sinusoidal crossover adjustment

    NASA Technical Reports Server (NTRS)

    Tai, Chang-Kou

    1988-01-01

    A new method (constrained sinusoidal crossover adjustment) for removing the orbit error in satellite altimetry is tested (using crossovers accumulated in the first 91 days of the Geosat non-repeat era in the tropical Pacific) and found to have excellent qualities. Two features distinguish the new method from the conventional bias-and-tilt crossover adjustment. First, a sine wave (with wavelength equaling the circumference of the Earth) is used to represent the orbit error for each satellite revolution, instead of the bias-and-tilt (and curvature, if necessary) approach for each segment of the satellite ground track. Secondly, the indeterminacy of the adjustment process is removed by a simple constraint minimizing the amplitudes of the sine waves, rather than by fixing selected tracks. Overall the new method is more accurate, more efficient, and much less cumbersome than the old. The idea of restricting the crossover adjustment to crossovers between tracks that are less than certain days apart in order to preserve the large-scale long-term oceanic variability is also tested with inconclusive results because the orbit error was unusually nonstationary in the initial 91 days of the GEOSAT mission.

  15. A new crossover operator in genetic programming for object classification.

    PubMed

    Zhang, Mengjie; Gao, Xiaoying; Lou, Weijun

    2007-10-01

    The crossover operator has been considered "the centre of the storm" in genetic programming (GP). However, many existing GP approaches to object recognition suggest that the standard GP crossover is not sufficiently powerful in producing good child programs due to the totally random choice of the crossover points. To deal with this problem, this paper introduces an approach with a new crossover operator in GP for object recognition, particularly object classification. In this approach, a local hill-climbing search is used in constructing good building blocks, a weight called looseness is introduced to identify the good building blocks in individual programs, and the looseness values are used as heuristics in choosing appropriate crossover points to preserve good building blocks. This approach is examined and compared with the standard crossover operator and the headless chicken crossover (HCC) method on a sequence of object classification problems. The results suggest that this approach outperforms the HCC, the standard crossover, and the standard crossover operator with hill climbing on all of these problems in terms of the classification accuracy. Although this approach spends a bit longer time than the standard crossover operator, it significantly improves the system efficiency over the HCC method.

  16. Bias induced spin transitions of spin crossover molecules: the role of charging effect.

    PubMed

    Hao, Hua; Jia, Ting; Zheng, Xiaohong; Zeng, Zhi

    2017-03-15

    The spin transition of spin crossover molecules induced by bias voltages from low spin to high spin was observed recently and several mechanisms were suggested to understand it. However, these mechanisms fail to explain the dependence of spin transitions on the bias polarity in experiments and thus may still be questionable. Based on a first-principles study, we propose that the bias-induced spin transition is triggered by a charging effect, namely, the filling of the lowest unoccupied molecular orbital of spin crossover molecules. Our proposal is substantiated by three steps: (1) the spin transition from low spin to high spin can be achieved by charging the isolated spin crossover molecules with one extra electron; (2) in molecular junctions, the charging of spin crossover molecules can be realized by electron transfer from electrodes to molecules under finite bias; (3) more importantly, the electron transfer is dependent on the bias polarity due to asymmetrical couplings of the sandwiched molecule with two electrodes. This mechanism satisfactorily explains the bias-polarity dependent spin transitions in experiments [Miyamachi et al., Nat. Commun., 2012, 3, 938; Gopakumar et al., Angew. Chem. Int. Ed., 2012, 51, 6262].

  17. Crossover between magnetic and electric edges in quantum Hall systems

    NASA Astrophysics Data System (ADS)

    Nogaret, Alain; Mondal, Puja; Kumar, Ankip; Ghosh, Sankalpa; Beere, Harvey; Ritchie, David

    2017-08-01

    We report on the transition from magnetic edge to electric edge transport in a split magnetic gate device which applies a notch magnetic field to a two-dimensional electron gas. The gate bias allows tuning the overlap of magnetic and electric edge wave functions on the scale of the magnetic length. Conduction at the magnetic edges, in the two-dimensional bulk, is found to compete with conduction at the electric edges until the magnetic edges become depleted. Current lines then move to the electrostatic edges as in the conventional quantum Hall picture. The conductivity was modeled using the quantum Boltzmann equation in the exact hybrid potential. The theory predicts the features of the bulk-edge crossover, in good agreement with experiment.

  18. A quantum genetic algorithm with quantum crossover and mutation operations

    NASA Astrophysics Data System (ADS)

    SaiToh, Akira; Rahimi, Robabeh; Nakahara, Mikio

    2013-11-01

    In the context of evolutionary quantum computing in the literal meaning, a quantum crossover operation has not been introduced so far. Here, we introduce a novel quantum genetic algorithm that has a quantum crossover procedure performing crossovers among all chromosomes in parallel for each generation. A complexity analysis shows that a quadratic speedup is achieved over its classical counterpart in the dominant factor of the run time to handle each generation.

  19. Crossover assessment of cardiolocomotor synchronization during running.

    PubMed

    Cerqueira, Lucenildo Silva; D'Affonsêca Netto, Aluizio; Mello, Roger Gomes Tavares; Nadal, Jurandir

    2017-02-01

    This study aimed at testing the hypothesis that positive cardiolocomotor coordination (CLC) measure occurs by chance during a running task where the heart rate (HR) is approximated to the step frequency (StepF). The electrocardiogram and electromyogram from the right gastrocnemius lateralis muscle were continuously recorded from ten healthy young men running at a paced rhythm of 152 step/min, to monitor HR and StepF. CLC was evaluated by phase synchrograms and the index of conditional probability (iCP). Results were validated with surrogate data and a crossover approach, where the HR of one subject was related to the StepF of another one, and comparisons were made combining subjects two by two. Six subjects showed synchrogram structures and high iCP values (≥0.8), suggesting the occurrence of physiological entrainment, when the HR reached the SF range. In crossover analysis, phase synchrograms and iCP presented similar behavior of original data when the HR from one subject was close enough to the SF from another one. Significant iCP values in 46 of 90 comparisons (51%) were observed, including all cases crossing signals among the six positive cases. Synchrogram and iCP tools currently employed for measuring CLC are not appropriate because they indicate the occurrence of this phenomenon even among subjects who ran on different days and times of each other.

  20. The fragile-to-strong dynamic crossover transition in confined water: nuclear magnetic resonance results

    NASA Astrophysics Data System (ADS)

    Mallamace, F.; Broccio, M.; Corsaro, C.; Faraone, A.; Wanderlingh, U.; Liu, L.; Mou, C.-Y.; Chen, S. H.

    2006-04-01

    By means of a nuclear magnetic resonance experiment, we give evidence of the existence of a fragile-to-strong dynamic crossover transition (FST) in confined water at a temperature TL=223±2K. We have studied the dynamics of water contained in 1D cylindrical nanoporous matrices (MCM-41-S) in the temperature range 190-280K, where experiments on bulk water were so far hampered by crystallization. The FST is clearly inferred from the T dependence of the inverse of the self-diffusion coefficient of water (1/D) as a crossover point from a non-Arrhenius to an Arrhenius behavior. The combination of the measured self-diffusion coefficient D and the average translational relaxation time ⟨τT⟩, as measured by neutron scattering, shows the predicted breakdown of Stokes-Einstein relation in deeply supercooled water.

  1. The fragile-to-strong dynamic crossover transition in confined water: nuclear magnetic resonance results.

    PubMed

    Mallamace, F; Broccio, M; Corsaro, C; Faraone, A; Wanderlingh, U; Liu, L; Mou, C-Y; Chen, S H

    2006-04-28

    By means of a nuclear magnetic resonance experiment, we give evidence of the existence of a fragile-to-strong dynamic crossover transition (FST) in confined water at a temperature T(L)=223+/-2 K. We have studied the dynamics of water contained in 1D cylindrical nanoporous matrices (MCM-41-S) in the temperature range 190-280 K, where experiments on bulk water were so far hampered by crystallization. The FST is clearly inferred from the T dependence of the inverse of the self-diffusion coefficient of water (1D) as a crossover point from a non-Arrhenius to an Arrhenius behavior. The combination of the measured self-diffusion coefficient D and the average translational relaxation time tau(T), as measured by neutron scattering, shows the predicted breakdown of Stokes-Einstein relation in deeply supercooled water.

  2. Clinostatic rotation decreases crossover frequencies in the fungus Sordaria macrospora Auersw.

    PubMed

    Henkel, J; Hock, B

    1991-12-01

    Two-factor crosses between the non-allelic spore colour mutants r2 and lu of the fungus Sordaria macrospora were used to investigate the effect of clinostatic rotation (= simulated weightlessness) on crossover frequencies. The experiment was carried out with different rotary directions at a rotary rate of 4 rpm. Second-division segregations of the gene lu, which result from crossover between the gene locus and centromere, are significantly smaller in the clinostat experiments than in the static controls. No differences were found between the two rotary directions. A similar influence of clinostatic rotation was not observed for the gene r2 which in contrast to the lu locus is located very close to the centromere. The suitability of this approach for the investigation of the effect of space flight conditions on cytogenetic processes is pointed out.

  3. All in the Family: Work-Family Enrichment and Crossover Among Farm Couples.

    PubMed

    Sprung, Justin M; Jex, Steve M

    2016-04-21

    This study expands upon the contextualization of the work-family interface by examining positive work-family experiences within the farming industry. Both individual and crossover effects were examined among a sample of 217 married farm couples. Results demonstrated multiple significant relationships between self-reported attitudes, work-family enrichment, and health outcomes. In addition, crossover effects reveal the importance of individual attitudes (husband work engagement and wife farm satisfaction) for spousal work-family enrichment and health outcomes. Furthermore, individual work-family enrichment was positively related to spousal psychological health and negatively related to spousal physical symptoms. Many of these findings remained significant after controlling for work-family conflict. Overall, our results suggest the potential beneficial impact of the integrated work-family dynamic associated with the farming profession for positive work-family experiences. Implications of these findings, as well as directions for future research, are discussed. (PsycINFO Database Record

  4. Research Update: The mechanocaloric potential of spin crossover compounds

    NASA Astrophysics Data System (ADS)

    Sandeman, Karl G.

    2016-11-01

    We present a first evaluation of the potential for spin crossover (SCO) compounds to be considered as a new class of giant mechanocaloric effect materials. From literature data on the variation of the spin crossover temperature with pressure, we estimate the maximum available adiabatic temperature change for several compounds and the relatively low pressures that may be required to observe these effects.

  5. Numerical simulation of bromine crossover behavior in flow battery

    NASA Astrophysics Data System (ADS)

    Jia, Yaobin; Cheng, Shijian; Chu, Dandan; Li, Xin

    2017-03-01

    Br2 and HBr has its own series of advantages as the positive electrolyte solution, so some batteries select the Br2/Br- as the positive electrolyte solution, such as sodium polysulfide/bromine flow battery, zinc/bromine flow battery, vanadium/ bromine flow batteries and hydrogen/bromine flow batteries. But the crossover benavior of bromine occurs in these batteries too, resulting in cross-contamination, capacity loss and affecting battery's performance. In this work, we build numerical models to study the influence of bromine crossover phenomenon on the three forms of bromine crossover, the concentration of electrolyte on the cathode side and the flow rate of the negative side in the quinone bromine flow battery, to find the main models affecting the bromine crossover and the impact of bromine crossover on battery performance. It was found that the three ways of crossover through the membranes was mainly by diffusion. By reducing the concentration of positive electrolyte solution, the bromine crossover can be reduced and Coulomb Efficiency can be improved. Rising the flow rate of the electrolyte solution on the negative side and reducing the differential between positive side's pressure and negative side's pressure can also reduce the amount of bromine crossover to improve Coulomb efficiency in the battery.

  6. A spin crossover ferrous complex with ordered magnetic ferric anions.

    PubMed

    Roubeau, Olivier; Evangelisti, Marco; Natividad, Eva

    2012-08-07

    The first tetrahaloferrate spin crossover compound, [Fe(Metz)(6)](FeBr(4))(2) (Metz = 1-methyltetrazole), is reported. The FeBr(4)(-) ions form ferromagnetically coupled 1D stacks and exhibit an antiferromagnetic order at 2.2 K, which coexists with the gradual spin crossover centred at 165 K.

  7. Electromagnetic pump stator frame having power crossover struts

    DOEpatents

    Fanning, Alan W.; Olich, Eugene E.

    1995-01-01

    A stator frame for an electromagnetic pump includes a casing joined to a hub by a plurality of circumferentially spaced apart struts. At least one electrically insulated power crossover lead extends through the hub, through a crossover one of the struts, and through the casing for carrying electrical current therethrough.

  8. Stress Crossover in Newlywed Marriage: A Longitudinal and Dyadic Perspective

    ERIC Educational Resources Information Center

    Neff, Lisa A.; Karney, Benjamin R.

    2007-01-01

    Studies of stress and marital quality often assess stress as an intrapersonal phenomenon, examining how spouses' stress may influence their own relationship well-being. Yet spouses' stress also may influence partners' relationship evaluations, a phenomenon referred to as stress crossover. This study examined stress crossover, and conditions that…

  9. Crossover ensembles of random matrices and skew-orthogonal polynomials

    SciTech Connect

    Kumar, Santosh; Pandey, Akhilesh

    2011-08-15

    Highlights: > We study crossover ensembles of Jacobi family of random matrices. > We consider correlations for orthogonal-unitary and symplectic-unitary crossovers. > We use the method of skew-orthogonal polynomials and quaternion determinants. > We prove universality of spectral correlations in crossover ensembles. > We discuss applications to quantum conductance and communication theory problems. - Abstract: In a recent paper (S. Kumar, A. Pandey, Phys. Rev. E, 79, 2009, p. 026211) we considered Jacobi family (including Laguerre and Gaussian cases) of random matrix ensembles and reported exact solutions of crossover problems involving time-reversal symmetry breaking. In the present paper we give details of the work. We start with Dyson's Brownian motion description of random matrix ensembles and obtain universal hierarchic relations among the unfolded correlation functions. For arbitrary dimensions we derive the joint probability density (jpd) of eigenvalues for all transitions leading to unitary ensembles as equilibrium ensembles. We focus on the orthogonal-unitary and symplectic-unitary crossovers and give generic expressions for jpd of eigenvalues, two-point kernels and n-level correlation functions. This involves generalization of the theory of skew-orthogonal polynomials to crossover ensembles. We also consider crossovers in the circular ensembles to show the generality of our method. In the large dimensionality limit, correlations in spectra with arbitrary initial density are shown to be universal when expressed in terms of a rescaled symmetry breaking parameter. Applications of our crossover results to communication theory and quantum conductance problems are also briefly discussed.

  10. Orbital Transfer Rocket Engine Technology High Velocity Ratio Diffusing Crossover

    DTIC Science & Technology

    1992-12-01

    Inducer Tip Seal ......................... 21 Figure 13 - Crossover Tester Thrust Balance Disk...Crossover Tester Rotor Mode Shapes for 500 Kibin ............ ,.....2 9 Figure 18 - Inducer Deflections In Wattr . 0 ’Figure 19 - Impeller Tip...Inducer and Impeller subassembly cantilevered on a shalt supported by two ball bearings. The finite element model of the rotor Is shown in Figure 14

  11. Stress Crossover in Newlywed Marriage: A Longitudinal and Dyadic Perspective

    ERIC Educational Resources Information Center

    Neff, Lisa A.; Karney, Benjamin R.

    2007-01-01

    Studies of stress and marital quality often assess stress as an intrapersonal phenomenon, examining how spouses' stress may influence their own relationship well-being. Yet spouses' stress also may influence partners' relationship evaluations, a phenomenon referred to as stress crossover. This study examined stress crossover, and conditions that…

  12. Inverted crossover resonance within one Zeeman manifold

    NASA Astrophysics Data System (ADS)

    Salter, L. A.; de Clercq, E.; McFerran, J. J.

    2017-08-01

    We carry out investigations of inverted crossover resonances (ICRs) in π-driven four-level systems where {{Δ }}F can be zero. Through the use of sub-Doppler frequency modulation spectroscopy of the (6{s}2) {}1{S}0 - (6s6p) {}3{P}1 transition in 171Yb the resonance becomes manifest. The centre frequency is inherently insensitive to first-order Zeeman shifts and equates to the two-level resonance frequency in the absence of a magnetic field. A rate equation model is used to help validate the nature of the resonance. Optical frequency measurements of the F\\prime =1/2 hyperfine line recorded over two months demonstrate a statistical uncertainty of 2 × 10-11. The ICR found with the F\\prime =3/2 line is used for 556 nm laser frequency stabilisation, which is an alternative means when applied to magneto-optical trapping of 171Yb.

  13. Neutrino dynamics below the electroweak crossover

    SciTech Connect

    Ghiglieri, J.; Laine, M.

    2016-07-12

    We estimate the thermal masses and damping rates of active (m< eV) and sterile (M∼ GeV) neutrinos with thermal momenta k∼3T at temperatures below the electroweak crossover (5 GeV 130 GeV remains an option. Our differential rates are tabulated in a form suitable for studies of specific scenarios with given neutrino Yukawa matrices.

  14. Neutrino dynamics below the electroweak crossover

    NASA Astrophysics Data System (ADS)

    Ghiglieri, J.; Laine, M.

    2016-07-01

    We estimate the thermal masses and damping rates of active (m < eV) and sterile (M ~ GeV) neutrinos with thermal momenta k~ 3T at temperatures below the electroweak crossover (5 GeV < T < 160 GeV) . These quantities fix the equilibration or ``washout'' rates of Standard Model lepton number densities. Sterile neutrinos interact via direct scatterings mediated by Yukawa couplings, and via their overlap with active neutrinos. Including all leading-order reactions we find that the washout rate generally exceeds the Hubble rate for 5 GeV < T < 30 GeV . Therefore it is challenging to generate a large lepton asymmetry facilitating dark matter computations operating at T < 5 GeV, whereas the generation of a baryon asymmetry at T > 130 GeV remains an option. Our differential rates are tabulated in a form suitable for studies of specific scenarios with given neutrino Yukawa matrices.

  15. Fuel cell membranes and crossover prevention

    DOEpatents

    Masel, Richard I.; York, Cynthia A.; Waszczuk, Piotr; Wieckowski, Andrzej

    2009-08-04

    A membrane electrode assembly for use with a direct organic fuel cell containing a formic acid fuel includes a solid polymer electrolyte having first and second surfaces, an anode on the first surface and a cathode on the second surface and electrically linked to the anode. The solid polymer electrolyte has a thickness t:.gtoreq..times..times..times..times. ##EQU00001## where C.sub.f is the formic acid fuel concentration over the anode, D.sub.f is the effective diffusivity of the fuel in the solid polymer electrolyte, K.sub.f is the equilibrium constant for partition coefficient for the fuel into the solid polymer electrolyte membrane, I is Faraday's constant n.sub.f is the number of electrons released when 1 molecule of the fuel is oxidized, and j.sub.f.sup.c is an empirically determined crossover rate of fuel above which the fuel cell does not operate.

  16. Fuel cell membranes and crossover prevention

    DOEpatents

    Masel, Richard I.; York, Cynthia A.; Waszczuk, Piotr; Wieckowski, Andrzej

    2009-08-04

    A membrane electrode assembly for use with a direct organic fuel cell containing a formic acid fuel includes a solid polymer electrolyte having first and second surfaces, an anode on the first surface and a cathode on the second surface and electrically linked to the anode. The solid polymer electrolyte has a thickness t:.gtoreq..times..times..times..times. ##EQU00001## where C.sub.f is the formic acid fuel concentration over the anode, D.sub.f is the effective diffusivity of the fuel in the solid polymer electrolyte, K.sub.f is the equilibrium constant for partition coefficient for the fuel into the solid polymer electrolyte membrane, I is Faraday's constant n.sub.f is the number of electrons released when 1 molecule of the fuel is oxidized, and j.sub.f.sup.c is an empirically determined crossover rate of fuel above which the fuel cell does not operate.

  17. Extended precedence preservative crossover for job shop scheduling problems

    NASA Astrophysics Data System (ADS)

    Ong, Chung Sin; Moin, Noor Hasnah; Omar, Mohd

    2013-04-01

    Job shop scheduling problems (JSSP) is one of difficult combinatorial scheduling problems. A wide range of genetic algorithms based on the two parents crossover have been applied to solve the problem but multi parents (more than two parents) crossover in solving the JSSP is still lacking. This paper proposes the extended precedence preservative crossover (EPPX) which uses multi parents for recombination in the genetic algorithms. EPPX is a variation of the precedence preservative crossover (PPX) which is one of the crossovers that perform well to find the solutions for the JSSP. EPPX is based on a vector to determine the gene selected in recombination for the next generation. Legalization of children (offspring) can be eliminated due to the JSSP representation encoded by using permutation with repetition that guarantees the feasibility of chromosomes. The simulations are performed on a set of benchmarks from the literatures and the results are compared to ensure the sustainability of multi parents recombination in solving the JSSP.

  18. An efficient algorithm for computing the crossovers in satellite altimetry

    NASA Technical Reports Server (NTRS)

    Tai, Chang-Kou

    1988-01-01

    An efficient algorithm has been devised to compute the crossovers in satellite altimetry. The significance of the crossovers is twofold. First, they are needed to perform the crossover adjustment to remove the orbit error. Secondly, they yield important insight into oceanic variability. Nevertheless, there is no published algorithm to make this very time consuming task easier, which is the goal of this report. The success of the algorithm is predicated on the ability to predict (by analytical means) the crossover coordinates to within 6 km and 1 sec of the true values. Hence, only one interpolation/extrapolation step on the data is needed to derive the crossover coordinates in contrast to the many interpolation/extrapolation operations usually needed to arrive at the same accuracy level if deprived of this information.

  19. Verification of an analytic fit for the vortex core profile in superfluid Fermi gases

    NASA Astrophysics Data System (ADS)

    Verhelst, Nick; Klimin, Serghei; Tempere, Jacques

    2017-02-01

    A characteristic property of superfluidity and -conductivity is the presence of quantized vortices in rotating systems. To study the BEC-BCS crossover the two most common methods are the Bogoliubov-De Gennes theory and the usage of an effective field theory. In order to simplify the calculations for one vortex, it is often assumed that the hyperbolic tangent yields a good approximation for the vortex structure. The combination of a variational vortex structure, together with cylindrical symmetry yields analytic (or numerically simple) expressions. The focus of this article is to investigate to what extent this analytic fit truly reflects the vortex structure throughout the BEC-BCS crossover at finite temperatures. The vortex structure will be determined using the effective field theory presented in [Eur. Phys. Journal B 88, 122 (2015)] and compared to the variational analytic solution. By doing this it is possible to see where these two structures agree, and where they differ. This comparison results in a range of applicability where the hyperbolic tangent will be a good fit for the vortex structure.

  20. Density response of a trapped Fermi gas: A crossover from the pair vibration mode to the Goldstone mode

    SciTech Connect

    Korolyuk, A.; Kinnunen, J. J.; Toermae, P.

    2011-09-15

    We consider the density response of a trapped two-component Fermi gas. Combining the Bogoliubov-deGennes method with the random phase approximation allows the study of both collective and single-particle excitations. Calculating the density response across a wide range of interactions, we observe a crossover from a weakly interacting pair vibration mode to a strongly interacting Goldstone mode. The crossover is associated with a depressed collective mode frequency and an increased damping rate, in agreement with density response experiments performed in strongly interacting atomic gases.

  1. Piezo- and thermo-switch investigation of the spin-crossover compound [Fe(PM-BiA) 2(NCS) 2

    NASA Astrophysics Data System (ADS)

    Tanasa, Radu; Stancu, Alexandru; Létard, Jean-François; Codjovi, Epiphane; Linares, Jorge; Varret, François

    2007-08-01

    We performed pressure and thermal switching experiments using a novel automatic temperature-pressure-reflectivity set-up. We report here on the pressure and temperature major hysteresis loops of the spin-crossover compound [Fe(PM-BiA) 2(NCS) 2]. The correlation between the temperature and pressure loops is discussed.

  2. Scale Invariance in 2D BCS-BEC Crossover

    NASA Astrophysics Data System (ADS)

    Sensarma, Rajdeep; Taylor, Edward; Randeria, Mohit

    2013-03-01

    In 2D BCS-BEC crossover, the frequency of the breathing mode in a harmonic trap, as well as the lower edge of the radio frequency spectroscopy response, show remarkable scale-invariance throughout the crossover regime, i.e. they are independent of the coupling constant. Using functional integral methods, we study the behaviour of these quantities in the 2D BCS-BEC crossover and comment on the possible reasons for this scale independence. RS was supported by DAE, Govt. of India. MR was supported by NSF Grant No. DMR-1006532. ET was supported by NSERC and the Canadian Institute for Advanced Research.

  3. A crossover in the mechanical response of nanocrystalline ceramics.

    PubMed

    Szlufarska, Izabela; Nakano, Aiichiro; Vashishta, Priya

    2005-08-05

    Multimillion-atom molecular dynamics simulation of indentation of nanocrystalline silicon carbide reveals unusual deformation mechanisms in brittle nanophase materials, resulting from the coexistence of brittle grains and soft amorphous grain boundary phases. Simulations predict a crossover from intergranular continuous deformation to intragrain discrete deformation at a critical indentation depth. The crossover arises from the interplay between cooperative grain sliding, grain rotations, and intergranular dislocation formation similar to stick-slip behavior. The crossover is also manifested in switching from deformation dominated by indentation-induced crystallization to deformation dominated by disordering, leading to amorphization. This interplay between deformation mechanisms is critical for the design of ceramics with superior mechanical properties.

  4. Pressure and Temperature Sensors Using Two Spin Crossover Materials

    PubMed Central

    Jureschi, Catalin-Maricel; Linares, Jorge; Boulmaali, Ayoub; Dahoo, Pierre Richard; Rotaru, Aurelian; Garcia, Yann

    2016-01-01

    The possibility of a new design concept for dual spin crossover based sensors for concomitant detection of both temperature and pressure is presented. It is conjectured from numerical results obtained by mean field approximation applied to a Ising-like model that using two different spin crossover compounds containing switching molecules with weak elastic interactions it is possible to simultaneously measure P and T. When the interaction parameters are optimized, the spin transition is gradual and for each spin crossover compounds, both temperature and pressure values being identified from their optical densities. This concept offers great perspectives for smart sensing devices. PMID:26848663

  5. Crossover Invariance Determined by Partner Choice for Meiotic DNA Break Repair

    PubMed Central

    Hyppa, Randy W.; Smith, Gerald R.

    2010-01-01

    SUMMARY Crossovers between meiotic homologs are crucial for their proper segregation, and crossover number and position are carefully controlled. Crossover homeostasis in budding yeast maintains crossovers at the expense of non-crossovers when double-strand DNA break (DSB) frequency is reduced. The mechanism of maintaining constant crossover levels in other species has been unknown. Here we investigate in fission yeast a different aspect of crossover control – the near invariance of crossover frequency per kb of DNA despite large variations in DSB intensity across the genome. Crossover invariance involves the choice of sister chromatid vs. homolog for DSB repair. At strong DSB hotspots, intersister repair outnumbers interhomolog repair ~3:1, but our genetic and physical data indicate the converse in DSB-cold regions. This unanticipated mechanism of crossover control may operate in many species and explain, for example, the large excess of DSBs over crossovers and the repair of DSBs on unpaired chromosomes in diverse species. PMID:20655467

  6. Qualitative determination of H2S crossover rates in nation membranes using ion-probe techniques

    SciTech Connect

    Brosha, Eric L; Rockward, Tommy; Uribe, Francisco A; Garzon, Fernando H

    2008-01-01

    Polymer electrolyte membrane fuel cells are sensitive to impurities that may be present in either the oxidizer or fuel. H2S, even at the ppb level, will have a dramatic and adverse affect on fuel cell performance. The H2S permeability through dry and humidified Nafion PEMFC membranes was studied using ion probe techniques. A sulfide anti-oxidant buffer solution was used to trap and concentrate trace quantities of H2S that permeated through 50 cm2samples of Nafion 117 and 212 membranes using a partial pressure difference up to I030ppm at room temperature. Experiments were conducted for up to 24 hours in order to achieve sulfide ion concentrations high enough to be precisely determined by subsequent titration with Pb(N03)2. The rate of H2S crossover for dry 117 and 212 were identical at 1.2e-7 g/min. Humidification increased the crossover rate to 5.ge-7 glmin and 1.8e-6 glmin for 117 and 212 respectively. Although the data collected in this work show that the rate of H2S crossover increases with water content and reduced membrane thickness, an accurate determination of permeation constants from this work was not possible because the H2S partial pressure was not constant throughout the experiment.

  7. Inversion for Refractivity Parameters Using a Dynamic Adaptive Cuckoo Search with Crossover Operator Algorithm.

    PubMed

    Zhang, Zhihua; Sheng, Zheng; Shi, Hanqing; Fan, Zhiqiang

    2016-01-01

    Using the RFC technique to estimate refractivity parameters is a complex nonlinear optimization problem. In this paper, an improved cuckoo search (CS) algorithm is proposed to deal with this problem. To enhance the performance of the CS algorithm, a parameter dynamic adaptive operation and crossover operation were integrated into the standard CS (DACS-CO). Rechenberg's 1/5 criteria combined with learning factor were used to control the parameter dynamic adaptive adjusting process. The crossover operation of genetic algorithm was utilized to guarantee the population diversity. The new hybrid algorithm has better local search ability and contributes to superior performance. To verify the ability of the DACS-CO algorithm to estimate atmospheric refractivity parameters, the simulation data and real radar clutter data are both implemented. The numerical experiments demonstrate that the DACS-CO algorithm can provide an effective method for near-real-time estimation of the atmospheric refractivity profile from radar clutter.

  8. Inversion for Refractivity Parameters Using a Dynamic Adaptive Cuckoo Search with Crossover Operator Algorithm

    PubMed Central

    Zhang, Zhihua; Sheng, Zheng; Shi, Hanqing; Fan, Zhiqiang

    2016-01-01

    Using the RFC technique to estimate refractivity parameters is a complex nonlinear optimization problem. In this paper, an improved cuckoo search (CS) algorithm is proposed to deal with this problem. To enhance the performance of the CS algorithm, a parameter dynamic adaptive operation and crossover operation were integrated into the standard CS (DACS-CO). Rechenberg's 1/5 criteria combined with learning factor were used to control the parameter dynamic adaptive adjusting process. The crossover operation of genetic algorithm was utilized to guarantee the population diversity. The new hybrid algorithm has better local search ability and contributes to superior performance. To verify the ability of the DACS-CO algorithm to estimate atmospheric refractivity parameters, the simulation data and real radar clutter data are both implemented. The numerical experiments demonstrate that the DACS-CO algorithm can provide an effective method for near-real-time estimation of the atmospheric refractivity profile from radar clutter. PMID:27212938

  9. Reentrant Resistive Behavior and Dimensional Crossover in Disordered Superconducting TiN Films.

    PubMed

    Postolova, Svetlana V; Mironov, Alexey Yu; Baklanov, Mikhail R; Vinokur, Valerii M; Baturina, Tatyana I

    2017-05-11

    A reentrant temperature dependence of the normal state resistance often referred to as the N-shaped temperature dependence, is omnipresent in disordered superconductors - ranging from high-temperature cuprates to ultrathin superconducting films - that experience superconductor-to-insulator transition. Yet, despite the ubiquity of this phenomenon its origin still remains a subject of debate. Here we investigate strongly disordered superconducting TiN films and demonstrate universality of the reentrant behavior. We offer a quantitative description of the N-shaped resistance curve. We show that upon cooling down the resistance first decreases linearly with temperature and then passes through the minimum that marks the 3D-2D crossover in the system. In the 2D temperature range the resistance first grows with decreasing temperature due to quantum contributions and eventually drops to zero as the system falls into a superconducting state. Our findings demonstrate the prime importance of disorder in dimensional crossover effects.

  10. Laser frequency stabilization using bichromatic crossover spectroscopy

    SciTech Connect

    Jeong, Taek; Seb Moon, Han

    2015-03-07

    We propose a Doppler-free spectroscopic method named bichromatic crossover spectroscopy (BCS), which we then use for the frequency stabilization of an off-resonant frequency that does not correspond to an atomic transition. The observed BCS in the 5S{sub 1/2} → 5P{sub 1/2} transition of {sup 87}Rb is related to the hyperfine structure of the conventional saturated absorption spectrum of this transition. Furthermore, the Doppler-free BCS is numerically calculated by considering all of the degenerate magnetic sublevels of the 5S{sub 1/2} → 5P{sub 1/2} transition in an atomic vapor cell, and is found to be in good agreement with the experimental results. Finally, we successfully achieve modulation-free off-resonant locking at the center frequency between the two 5S{sub 1/2}(F = 1 and 2) → 5P{sub 1/2}(F′ = 1) transitions using a polarization rotation of the BCS. The laser frequency stability was estimated to be the Allan variance of 2.1 × 10{sup −10} at 1 s.

  11. Electrostatically-tuned dimensional crossover in nanowires

    NASA Astrophysics Data System (ADS)

    Tomczyk, Michelle; Cheng, Guanglei; Huang, Mengchen; Lee, Hyungwoo; Eom, Chang-Beom; Irvin, Patrick; Levy, Jeremy

    The electron system at the interface of two complex oxides, LaAlO3 and SrTiO3, exhibits a number of interesting strongly-correlated electronic properties, such as superconductivity and spin-orbit coupling. Reduced dimensionality is made accessible through nanowire devices created with conducting AFM lithography. Here, we describe an electrostatically-controlled dimensionality crossover in weak antilocalization behavior of LaAlO3/SrTiO3 nanowires at low temperature. These measurements give insight to the interplay of spin-orbit coupling and dimensionality. Characterizing the behavior of the strongly-correlated electronic properties in these reduced dimensions is necessary in order to develop this system as a multifunctional nanoelectronics platform. We gratefully acknowledge financial support from the following agencies and grants: ARO (W911NF-08-1-0317), AFOSR FA9550-10-1-0524 (JL) and FA9550-12-1-0342 (CBE), and NSF (DMR-1104191, DMR-1124131 (JL), ONR N00014-15-1-2847 (JL) and DMR-1234096 (CBE).

  12. Estimating efficacy in trials with selective crossover.

    PubMed

    Brentnall, Adam R; Sasieni, Peter; Cuzick, Jack

    2017-03-15

    When one arm in a trial has a worse early endpoint such as recurrence, a data-monitoring committee might recommend that all participants are offered the apparently superior treatment. The resultant crossover makes it difficult to measure differences between arms thereafter, including for longer-term endpoints such as mortality and disease-specific mortality. In this paper, we consider estimators of the efficacy of treatment on those who would not cross over if randomised to the apparently inferior arm. Binomial and proportional hazards maximum likelihood estimators are developed. The binomial estimator is applied to analysis of a breast cancer treatment trial and compared with intention-to-treat and inverse probability weighting estimators. Full and partial likelihood proportional-hazard model estimators are assessed through computer simulations, where they had similar bias and variance. The new efficacy estimators extend those for all-or-none compliance to this important problem. © 2017 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.

  13. Crossover from retro to specular Andreev reflections in bilayer graphene

    NASA Astrophysics Data System (ADS)

    Efetov, Dmitri K.; Efetov, Konstantin B.

    2016-08-01

    Ongoing experimental progress in the preparation of ultraclean graphene/superconductor (SC) interfaces enabled the recent observation of specular interband Andreev reflections (ARs) at bilayer graphene (BLG )/NbSe2 van der Waals interfaces [Efetov et al., Nat. Phys. 12, 328 (2016), 10.1038/nphys3583]. Motivated by this experiment we theoretically study the differential conductance across a BLG/SC interface at the continuous transition from high to ultralow Fermi energies EF in BLG. Using the Bogoliubov-de Gennes equations and the Blonder-Tinkham-Klapwijk formalism we derive analytical expressions for the differential conductance across the BLG/SC interface. We find a characteristic signature of the crossover from intraband retro (high EF) to interband specular (low EF) ARs that manifests itself in a strongly suppressed interfacial conductance when the excitation energy |ɛ |=| EF|<Δ (the SC gap). The sharpness of these conductance dips is strongly dependent on the size of the potential step at the BLG/SC interface U0.

  14. Characterization of Non-Specific Crossover in SPLITT Fractionation

    PubMed Central

    Williams, P. Stephen; Hoyos, Mauricio; Kurowski, Pascal; Salhi, Dorra; Moore, Lee R.; Zborowski, Maciej

    2009-01-01

    Split-flow thin channel (SPLITT) fractionation is a technique for continuous separation of particles or macromolecules in a fluid stream into fractions according to the lateral migration induced by application of a field perpendicular to the direction of flow. Typical applications have involved isolation of different fractions from a polydisperse sample. Some specialized applications involve the separation of the fraction influenced by the transverse field from the fraction that is not. For example, immuno-magnetically labeled biological cells may be separated from non-labeled cells with the application of a transverse magnetic field gradient. In such cases, it may be critically important to minimize contamination of the labeled cells with non-labeled cells while at the same time maximizing the throughput. Such contamination is known as non-specific crossover (NSC) and refers to the real or apparent migration of non-mobile particles or cells across streamlines with the mobile material. The possible mechanisms for NSC are discussed, and experimental results interpreted in terms of shear-induced diffusion (SID) caused by viscous interactions between particles in a sheared flow. It is concluded that SID may contribute to NSC, but that further experiments and mathematical modeling are necessary to more fully explore the phenomenon. PMID:18698797

  15. Self-affinity and Crossover of A Clay Deposit

    NASA Astrophysics Data System (ADS)

    Fossum, J. O.; Huru Bergene, H.; Hansen, A.; Manificat, G.

    Self-affine dehydrated colloidal deposits on fresh mica surfaces of the synthetic 2:1 smectite clay laponite have been studied by means of Atomic Force Microscopy. AFM images of these prepared assemblies of sol and gel aggregates have been analyzed both by means of standard AFM software, and wavelet methods. The deposited surfaces show an anti-persistent to persistent crossover with a clay concentration dependent crossover length. It is thus concluded that the investigated electrolyte concentrations play a minor role

  16. The kinetochore prevents centromere-proximal crossover recombination during meiosis

    PubMed Central

    Vincenten, Nadine; Kuhl, Lisa-Marie; Lam, Isabel; Oke, Ashwini; Kerr, Alastair RW; Hochwagen, Andreas; Fung, Jennifer; Keeney, Scott; Vader, Gerben; Marston, Adèle L

    2015-01-01

    During meiosis, crossover recombination is essential to link homologous chromosomes and drive faithful chromosome segregation. Crossover recombination is non-random across the genome, and centromere-proximal crossovers are associated with an increased risk of aneuploidy, including Trisomy 21 in humans. Here, we identify the conserved Ctf19/CCAN kinetochore sub-complex as a major factor that minimizes potentially deleterious centromere-proximal crossovers in budding yeast. We uncover multi-layered suppression of pericentromeric recombination by the Ctf19 complex, operating across distinct chromosomal distances. The Ctf19 complex prevents meiotic DNA break formation, the initiating event of recombination, proximal to the centromere. The Ctf19 complex independently drives the enrichment of cohesin throughout the broader pericentromere to suppress crossovers, but not DNA breaks. This non-canonical role of the kinetochore in defining a chromosome domain that is refractory to crossovers adds a new layer of functionality by which the kinetochore prevents the incidence of chromosome segregation errors that generate aneuploid gametes. DOI: http://dx.doi.org/10.7554/eLife.10850.001 PMID:26653857

  17. Crossovers from parity conserving to directed percolation universality.

    PubMed

    Odor, Géza; Menyhárd, Nóra

    2008-10-01

    The crossover behavior of various models exhibiting phase transition to absorbing phase with parity conserving class has been investigated by numerical simulations and cluster mean-field method. In case of models exhibiting Z_2 symmetric absorbing phases (the cellular automaton version of the nonequilibrium kinetic Ising model (NEKIMCA) and a stochastic cellular automaton invented by Grassberger, Krause, and von der Twer [J. Phys. A 17, L105 (1984)]) the introduction of an external symmetry breaking field causes a crossover to kink parity conserving models characterized by dynamical scaling of the directed percolation (DP) and the crossover exponent: 1/phi approximately equal to 0.53(2) . In the case of a branching and annihilating random walk model with an even number of offspring (dual to NEKIMCA) the introduction of spontaneous particle decay destroys the parity conservation and results in a crossover to the DP class characterized by the crossover exponent: 1/phi approximately equal to 0.205(5) . The two different kinds of crossover operators cannot be mapped onto each other and the resulting models show a diversity within the DP universality class in one dimension. These subclasses differ in cluster scaling exponents.

  18. The dynamical crossover in attractive colloidal systems

    SciTech Connect

    Mallamace, Francesco; Corsaro, Carmelo; Stanley, H. Eugene; Mallamace, Domenico; Chen, Sow-Hsin

    2013-12-07

    We study the dynamical arrest in an adhesive hard-sphere colloidal system. We examine a micellar suspension of the Pluronic-L64 surfactant in the temperature (T) and volume fraction (ϕ) phase diagram. According to mode-coupling theory (MCT), this system is characterized by a cusp-like singularity and two glassy phases: an attractive glass (AG) phase and a repulsive glass (RG) phase. The T − ϕ phase diagram of this system as confirmed by a previous series of scattering data also exhibits a Percolation Threshold (PT) line, a reentrant behavior (AG-liquid-RG), and a glass-to-glass transition. The AG phase can be generated out of the liquid phase by using T and ϕ as control parameters. We utilize viscosity and nuclear magnetic resonance (NMR) techniques. NMR data confirm all the characteristic properties of the colloidal system phase diagram and give evidence of the onset of a fractal-like percolating structure at a precise threshold. The MCT scaling laws used to study the shear viscosity as a function of ϕ and T show in both cases a fragile-to-strong liquid glass-forming dynamic crossover (FSC) located near the percolation threshold where the clustering process is fully developed. These results suggest a larger thermodynamic generality for this phenomenon, which is usually studied only as a function of the temperature. We also find that the critical values of the control parameters, coincident with the PT line, define the locus of the FSC. In the region between the FSC and the glass transition lines the system dynamics are dominated by clustering effects. We thus demonstrate that it is possible, using the conceptual framework provided by extended mode-coupling theory, to describe the way a system approaches dynamic arrest, taking into account both cage and hopping effects.

  19. The dynamical crossover in attractive colloidal systems.

    PubMed

    Mallamace, Francesco; Corsaro, Carmelo; Stanley, H Eugene; Mallamace, Domenico; Chen, Sow-Hsin

    2013-12-07

    We study the dynamical arrest in an adhesive hard-sphere colloidal system. We examine a micellar suspension of the Pluronic-L64 surfactant in the temperature (T) and volume fraction (φ) phase diagram. According to mode-coupling theory (MCT), this system is characterized by a cusp-like singularity and two glassy phases: an attractive glass (AG) phase and a repulsive glass (RG) phase. The T - φ phase diagram of this system as confirmed by a previous series of scattering data also exhibits a Percolation Threshold (PT) line, a reentrant behavior (AG-liquid-RG), and a glass-to-glass transition. The AG phase can be generated out of the liquid phase by using T and φ as control parameters. We utilize viscosity and nuclear magnetic resonance (NMR) techniques. NMR data confirm all the characteristic properties of the colloidal system phase diagram and give evidence of the onset of a fractal-like percolating structure at a precise threshold. The MCT scaling laws used to study the shear viscosity as a function of φ and T show in both cases a fragile-to-strong liquid glass-forming dynamic crossover (FSC) located near the percolation threshold where the clustering process is fully developed. These results suggest a larger thermodynamic generality for this phenomenon, which is usually studied only as a function of the temperature. We also find that the critical values of the control parameters, coincident with the PT line, define the locus of the FSC. In the region between the FSC and the glass transition lines the system dynamics are dominated by clustering effects. We thus demonstrate that it is possible, using the conceptual framework provided by extended mode-coupling theory, to describe the way a system approaches dynamic arrest, taking into account both cage and hopping effects.

  20. Fermi-to-Bose crossover in a trapped quasi-2D gas of fermionic atoms

    NASA Astrophysics Data System (ADS)

    Turlapov, A. V.; Kagan, M. Yu

    2017-09-01

    The physics of many-body systems where particles are restricted to move in two spatial dimensions is challenging and even controversial: on one hand, neither long-range order nor Bose condensation may appear in infinite uniform 2D systems at finite temperature, on the other hand this does not prohibit superfluidity or superconductivity. Moreover, 2D superconductors, such as cuprates, are among the systems with the highest critical temperatures. Ultracold atoms are a platform for studying 2D physics. Unique from other physical systems, quantum statistics may be completely changed in an ultracold gas: an atomic Fermi gas may be smoothly crossed over into a gas of Bose molecules (or dimers) by tuning interatomic interactions. We review recent experiments where such crossover has been demonstrated, as well as critical phenomena in the Fermi-to-Bose crossover. We also present simple theoretical models describing the gas at different points of the crossover and compare the data to these and more advanced models.

  1. Mood spillover and crossover among dual-earner couples: a cell phone event sampling study.

    PubMed

    Song, Zhaoli; Foo, Maw-Der; Uy, Marilyn A

    2008-03-01

    In this study, the authors examined affective experiences of dual-earner couples. More specifically, the authors explored how momentary moods can spill over between work and family and cross over from one spouse to another. Fifty couples used their cell phones to provide reports of their momentary moods over 8 consecutive days. Results show significant spillover and crossover effects for both positive and negative moods. Work orientation moderated negative mood spillover from work to home, and the presence of children in the family decreased negative mood crossover between spouses. Crossover was observed when spouses were physically together and when the time interval between the spouses' reports was short. With this study, the authors contribute to the work and family research by examining the nature of mood transfers among dual-earner couples, including the direction, valence, and moderators of these transfers across work and family domains. The authors also contribute to the event sampling methodology by introducing a new method of using cell phones to collect momentary data. Copyright 2008 APA

  2. The commerce and crossover of resources: resource conservation in the service of resilience.

    PubMed

    Chen, Shoshi; Westman, Mina; Hobfoll, Stevan E

    2015-04-01

    Conservation of resources (COR) theory was originally introduced as a framework for understanding and predicting the consequences of major and traumatic stress, but following the work of Hobfoll and Shirom (1993), COR theory has been adopted to understanding and predicting work-related stress and both the stress and resilience that occur within work settings and work culture. COR theory underscores the critical role of resource possession, lack, loss and gain and depicts personal, social and material resources co-travelling in resource caravans, rather than piecemeal. We briefly review the principles of COR theory and integrate it in the crossover model, which provides a key mechanism for multi-person exchange of emotions, experiences and resources. Understanding the impact of resource reservoirs, resource passageways and crossover provides a framework for research and intervention promoting resilience to employees as well as to organizations. It emphasizes that the creation and maintenance of resource caravan passageways promote resource gain climates through resource crossover processes. Copyright © 2014 John Wiley & Sons, Ltd.

  3. [Case-crossover design: Basic essentials and applications].

    PubMed

    Carracedo-Martínez, Eduardo; Tobías, Aurelio; Saez, Marc; Taracido, Margarita; Figueiras, Adolfo

    2009-01-01

    Case-crossover analysis is an observational epidemiological design that was proposed by Maclure in 1991 to assess whether a given intermittent or unusual exposure may have triggered an immediate short-term, acute event. The present article outlines the basics of case-crossover designs, as well as their applications and limitations. The case-crossover design is based on exclusively selecting case subjects. To calculate relative risk, exposure during the period of time prior to the event (case period) is compared against the same subject's exposure during one or more control periods. This method is only appropriate when the exposures are transient in time and have acute short-term effects. For exposures in which there is no trend, a unidirectional approach is the most frequent and consists of selecting one or more control periods prior to the case period. When the exposure displays a time trend (e.g., air pollution), a unidirectional approach will yield biased estimates, and therefore bidirectional case-crossover designs are used, which select control time intervals preceding and subsequent to that of the event. The case-crossover design is being increasingly used across a wide range of fields, including factors triggering traffic, occupational and domestic accidents and acute myocardial infarction, and those involved in air pollution and health and pharmacoepidemiology, among others. Insofar as data-analysis is concerned, case-crossover designs can generally be regarded as matched case-control studies and consequently conditional logistic regression can be applied. Lastly, this study analyzes practical examples of distinct applications of the case-crossover design.

  4. Detection of crossover time scales in multifractal detrended fluctuation analysis

    NASA Astrophysics Data System (ADS)

    Ge, Erjia; Leung, Yee

    2013-04-01

    Fractal is employed in this paper as a scale-based method for the identification of the scaling behavior of time series. Many spatial and temporal processes exhibiting complex multi(mono)-scaling behaviors are fractals. One of the important concepts in fractals is crossover time scale(s) that separates distinct regimes having different fractal scaling behaviors. A common method is multifractal detrended fluctuation analysis (MF-DFA). The detection of crossover time scale(s) is, however, relatively subjective since it has been made without rigorous statistical procedures and has generally been determined by eye balling or subjective observation. Crossover time scales such determined may be spurious and problematic. It may not reflect the genuine underlying scaling behavior of a time series. The purpose of this paper is to propose a statistical procedure to model complex fractal scaling behaviors and reliably identify the crossover time scales under MF-DFA. The scaling-identification regression model, grounded on a solid statistical foundation, is first proposed to describe multi-scaling behaviors of fractals. Through the regression analysis and statistical inference, we can (1) identify the crossover time scales that cannot be detected by eye-balling observation, (2) determine the number and locations of the genuine crossover time scales, (3) give confidence intervals for the crossover time scales, and (4) establish the statistically significant regression model depicting the underlying scaling behavior of a time series. To substantive our argument, the regression model is applied to analyze the multi-scaling behaviors of avian-influenza outbreaks, water consumption, daily mean temperature, and rainfall of Hong Kong. Through the proposed model, we can have a deeper understanding of fractals in general and a statistical approach to identify multi-scaling behavior under MF-DFA in particular.

  5. Macrocycle-based spin-crossover materials.

    PubMed

    El Hajj, Fatima; Sebki, Ghania; Patinec, Véronique; Marchivie, Mathieu; Triki, Smail; Handel, Henri; Yefsah, Said; Tripier, Raphaël; Gómez-García, Carlos J; Coronado, Eugenio

    2009-11-02

    New iron(II) complexes of formula [Fe(L1)](BF(4))(2) (1) and [Fe(L2)](BF(4))(2) x H(2)O (2) (L1 = 1,7-bis(2'-pyridylmethyl)-1,4,7,10-tetraazacyclododecane; L2 = 1,8-bis(2'-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane) have been synthesized and characterized by infrared spectroscopy, variable-temperature single-crystal X-ray diffraction, and variable-temperature magnetic susceptibility measurements. The crystal structure determinations of 1 and 2 reveal in both cases discrete iron(II) monomeric structures in which the two functionalized tetraazamacrocycles (L1 and L2) act as hexadentate ligands; the iron(II) ions are coordinated with six nitrogen atoms: four from the macrocycle and two from two pyridine groups occupying two cis positions around the metal ion. In 1, the N-Fe-N bond angles indicate that the Fe(II) ion adopts an unusual distorted trigonal prismatic geometry. In agreement with the observed paramagnetic behavior, the average of the six Fe-N distances at 293 K (2.218(6) A) and at 90 K (2.209(2) A) correspond well with distances observed for high-spin (HS) Fe(II) complexes with a coordination index of 6. For 2, the Fe(II) ion adopts a distorted octahedral geometry for which the six Fe-N distances (average 2.197(4) A) at room temperature are in the range expected for HS Fe(II) complexes. The crystal structure solved at 90 K showed a strong modification of the iron coordination sphere, suggesting the presence of a spin-crossover transition from HS to low spin (LS). Surprisingly, the averaged Fe-N value (2.077(4) A) at this temperature is not in agreement with the magnetic measurements since the chi(m)T product versus T showed a full LS state at 90 K. This may be explained by the presence of important distortions arising from the macrocycle constraints. To understand how the crystal and the lattice parameters were affected by the magnetic transition, the temperature dependence of the lattice parameters of 2 was determined in the range 293-90 K: the a and

  6. Inhibition of the Smc5/6 Complex during Meiosis Perturbs Joint Molecule Formation and Resolution without Significantly Changing Crossover or Non-crossover Levels

    PubMed Central

    Lilienthal, Ingrid; Kanno, Takaharu; Sjögren, Camilla

    2013-01-01

    Meiosis is a specialized cell division used by diploid organisms to form haploid gametes for sexual reproduction. Central to this reductive division is repair of endogenous DNA double-strand breaks (DSBs) induced by the meiosis-specific enzyme Spo11. These DSBs are repaired in a process called homologous recombination using the sister chromatid or the homologous chromosome as a repair template, with the homolog being the preferred substrate during meiosis. Specific products of inter-homolog recombination, called crossovers, are essential for proper homolog segregation at the first meiotic nuclear division in budding yeast and mice. This study identifies an essential role for the conserved Structural Maintenance of Chromosomes (SMC) 5/6 protein complex during meiotic recombination in budding yeast. Meiosis-specific smc5/6 mutants experience a block in DNA segregation without hindering meiotic progression. Establishment and removal of meiotic sister chromatid cohesin are independent of functional Smc6 protein. smc6 mutants also have normal levels of DSB formation and repair. Eliminating DSBs rescues the segregation block in smc5/6 mutants, suggesting that the complex has a function during meiotic recombination. Accordingly, smc6 mutants accumulate high levels of recombination intermediates in the form of joint molecules. Many of these joint molecules are formed between sister chromatids, which is not normally observed in wild-type cells. The normal formation of crossovers in smc6 mutants supports the notion that mainly inter-sister joint molecule resolution is impaired. In addition, return-to-function studies indicate that the Smc5/6 complex performs its most important functions during joint molecule resolution without influencing crossover formation. These results suggest that the Smc5/6 complex aids primarily in the resolution of joint molecules formed outside of canonical inter-homolog pathways. PMID:24244180

  7. Interference-mediated synaptonemal complex formation with embedded crossover designation.

    PubMed

    Zhang, Liangran; Espagne, Eric; de Muyt, Arnaud; Zickler, Denise; Kleckner, Nancy E

    2014-11-25

    Biological systems exhibit complex patterns at length scales ranging from the molecular to the organismic. Along chromosomes, events often occur stochastically at different positions in different nuclei but nonetheless tend to be relatively evenly spaced. Examples include replication origin firings, formation of chromatin loops along chromosome axes and, during meiosis, localization of crossover recombination sites ("crossover interference"). We present evidence in the fungus Sordaria macrospora that crossover interference is part of a broader pattern that includes synaptonemal complex (SC) nucleation. This pattern comprises relatively evenly spaced SC nucleation sites, among which a subset are crossover sites that show a classical interference distribution. This pattern ensures that SC forms regularly along the entire length of the chromosome as required for the maintenance of homolog pairing while concomitantly having crossover interactions locally embedded within the SC structure as required for both DNA recombination and structural events of chiasma formation. This pattern can be explained by a threshold-based designation and spreading interference process. This model can be generalized to give diverse types of related and/or partially overlapping patterns, in two or more dimensions, for any type of object.

  8. Interference-mediated synaptonemal complex formation with embedded crossover designation

    PubMed Central

    Zhang, Liangran; Espagne, Eric; de Muyt, Arnaud; Zickler, Denise; Kleckner, Nancy E.

    2014-01-01

    Biological systems exhibit complex patterns at length scales ranging from the molecular to the organismic. Along chromosomes, events often occur stochastically at different positions in different nuclei but nonetheless tend to be relatively evenly spaced. Examples include replication origin firings, formation of chromatin loops along chromosome axes and, during meiosis, localization of crossover recombination sites (“crossover interference”). We present evidence in the fungus Sordaria macrospora that crossover interference is part of a broader pattern that includes synaptonemal complex (SC) nucleation. This pattern comprises relatively evenly spaced SC nucleation sites, among which a subset are crossover sites that show a classical interference distribution. This pattern ensures that SC forms regularly along the entire length of the chromosome as required for the maintenance of homolog pairing while concomitantly having crossover interactions locally embedded within the SC structure as required for both DNA recombination and structural events of chiasma formation. This pattern can be explained by a threshold-based designation and spreading interference process. This model can be generalized to give diverse types of related and/or partially overlapping patterns, in two or more dimensions, for any type of object. PMID:25380597

  9. Orbital transfer vehicle engine technology high velocity ratio diffusing crossover

    NASA Astrophysics Data System (ADS)

    Lariviere, Brian W.

    1992-12-01

    High speed, high efficiency head rise multistage pumps require continuous passage diffusing crossovers to effectively convey the pumped fluid from the exit of one impeller to the inlet of the next impeller. On Rocketdyne's Orbital Transfer Vehicle (OTV), the MK49-F, a three stage high pressure liquid hydrogen turbopump, utilizes a 6.23 velocity ratio diffusing crossover. This velocity ratio approaches the diffusion limits for stable and efficient flow over the operating conditions required by the OTV system. The design of the high velocity ratio diffusing crossover was based on advanced analytical techniques anchored by previous tests of stationary two-dimensional diffusers with steady flow. To secure the design and the analytical techniques, tests were required with the unsteady whirling characteristics produced by an impeller. A tester was designed and fabricated using a 2.85 times scale model of the MK49-F turbopumps first stage, including the inducer, impeller, and the diffusing crossover. Water and air tests were completed to evaluate the large scale turbulence, non-uniform velocity, and non-steady velocity on the pump and crossover head and efficiency. Suction performance tests from 80 percent to 124 percent of design flow were completed in water to assess these pump characteristics. Pump and diffuser performance from the water and air tests were compared with the actual MK49-F test data in liquid hydrogen.

  10. Orbital Transfer Vehicle Engine Technology High Velocity Ratio Diffusing Crossover

    NASA Technical Reports Server (NTRS)

    Lariviere, Brian W.

    1992-01-01

    High speed, high efficiency head rise multistage pumps require continuous passage diffusing crossovers to effectively convey the pumped fluid from the exit of one impeller to the inlet of the next impeller. On Rocketdyne's Orbital Transfer Vehicle (OTV), the MK49-F, a three stage high pressure liquid hydrogen turbopump, utilizes a 6.23 velocity ratio diffusing crossover. This velocity ratio approaches the diffusion limits for stable and efficient flow over the operating conditions required by the OTV system. The design of the high velocity ratio diffusing crossover was based on advanced analytical techniques anchored by previous tests of stationary two-dimensional diffusers with steady flow. To secure the design and the analytical techniques, tests were required with the unsteady whirling characteristics produced by an impeller. A tester was designed and fabricated using a 2.85 times scale model of the MK49-F turbopumps first stage, including the inducer, impeller, and the diffusing crossover. Water and air tests were completed to evaluate the large scale turbulence, non-uniform velocity, and non-steady velocity on the pump and crossover head and efficiency. Suction performance tests from 80 percent to 124 percent of design flow were completed in water to assess these pump characteristics. Pump and diffuser performance from the water and air tests were compared with the actual MK49-F test data in liquid hydrogen.

  11. A Link between Meiotic Prophase Progression and CrossoverControl

    SciTech Connect

    Carlton, Peter M.; Farruggio, Alfonso P.; Dernburg, Abby F.

    2005-07-06

    During meiosis, most organisms ensure that homologous chromosomes undergo at least one exchange of DNA, or crossover, to link chromosomes together and accomplish proper segregation. How each chromosome receives a minimum of one crossover is unknown. During early meiosis in Caenorhabditis elegans and many other species, chromosomes adopt a polarized organization within the nucleus, which normally disappears upon completion of homolog synapsis. Mutations that impair synapsis even between a single pair of chromosomes in C. elegans delay this nuclear reorganization. We quantified this delay by developing a classification scheme for discrete stages of meiosis. Immunofluorescence localization of RAD-51 protein revealed that delayed meiotic cells also contained persistent recombination intermediates. Through genetic analysis, we found that this cytological delay in meiotic progression requires double-strand breaks and the function of the crossover-promoting heteroduplex HIM-14 (Msh4) and MSH-5. Failure of X chromosome synapsis also resulted in impaired crossover control on autosomes, which may result from greater numbers and persistence of recombination intermediates in the delayed nuclei. We conclude that maturation of recombination events on chromosomes promotes meiotic progression, and is coupled to the regulation of crossover number and placement. Our results have broad implications for the interpretation of meiotic mutants, as we have shown that asynapsis of a single chromosome pair can exert global effects on meiotic progression and recombination frequency.

  12. Eating marshmallows reduces ileostomy output: a randomized crossover trial.

    PubMed

    Clarebrough, E; Guest, G; Stupart, D

    2015-12-01

    Anecdotally, many ostomates believe that eating marshmallows can reduce ileostomy effluent. There is a plausible mechanism for this, as the gelatine contained in marshmallows may thicken small bowel fluid, but there is currently no evidence that this is effective. This was a randomized crossover trial. Adult patients with well-established ileostomies were included. Ileostomy output was measured for 1 week during which three marshmallows were consumed three times daily, and for one control week where marshmallows were not eaten. There was a 2-day washout period. Patients were randomly allocated to whether the control or intervention week occurred first. In addition, a questionnaire was administered regarding patient's subjective experience of their ileostomy function. Thirty-one participants were recruited; 28 completed the study. There was a median reduction in ileostomy output volume of 75 ml per day during the study period (P = 0.0054, 95% confidence interval 23.4-678.3) compared with the control week. Twenty of 28 subjects (71%) experienced a reduction in their ileostomy output, two had no change and six reported an increase. During the study period, participants reported fewer ileostomy bag changes (median five per day vs six in the control period, P = 0.0255). Twenty of 28 (71%) reported that the ileostomy effluent was thicker during the study week (P = 0.023). Overall 19 (68%) participants stated they would use marshmallows in the future if they wanted to reduce or thicken their ileostomy output. Eating marshmallows leads to a small but statistically significant reduction in ileostomy output. Colorectal Disease © 2015 The Association of Coloproctology of Great Britain and Ireland.

  13. Magnetic tuning of the relativistic BCS-BEC crossover

    NASA Astrophysics Data System (ADS)

    Wang, Jin-Cheng; de La Incera, Vivian; Ferrer, Efrain J.; Wang, Qun

    2011-09-01

    The effect of an applied magnetic field in the crossover from Bose-Einstein condensate (BEC) to Bardeen-Cooper-Schrieffer (BCS) pairing regimes is investigated. We use a model of relativistic fermions and bosons inspired by those previously used in the context of cold fermionic atoms and in the magnetic-color-flavor-locking phase of color superconductivity. It turns out that, as with cold atom systems, an applied magnetic field can also tune the BCS-BEC crossover in the relativistic case. We find that no matter what the initial state is at B=0, for large enough magnetic fields the system always settles into a pure BCS regime. In contrast to the atomic case, the magnetic field tuning of the crossover in the relativistic system is not connected to a Feshbach resonance, but to the relative numbers of Landau levels with either BEC or BCS type of dispersion relations that are occupied at each magnetic field strength.

  14. Crossover from equilibration to aging: Nonequilibrium theory versus simulations

    NASA Astrophysics Data System (ADS)

    Mendoza-Méndez, P.; Lázaro-Lázaro, E.; Sánchez-Díaz, L. E.; Ramírez-González, P. E.; Pérez-Ángel, G.; Medina-Noyola, M.

    2017-08-01

    Understanding glasses and the glass transition requires comprehending the nature of the crossover from the ergodic (or equilibrium) regime, in which the stationary properties of the system have no history dependence, to the mysterious glass transition region, where the measured properties are nonstationary and depend on the protocol of preparation. In this work we use nonequilibrium molecular dynamics simulations to test the main features of the crossover predicted by the molecular version of the recently developed multicomponent nonequilibrium self-consistent generalized Langevin equation theory. According to this theory, the glass transition involves the abrupt passage from the ordinary pattern of full equilibration to the aging scenario characteristic of glass-forming liquids. The same theory explains that this abrupt transition will always be observed as a blurred crossover due to the unavoidable finiteness of the time window of any experimental observation. We find that within their finite waiting-time window, the simulations confirm the general trends predicted by the theory.

  15. Self-affine crossover length in a layered silicate deposit.

    PubMed

    Fossum, J O; Bergene, H H; Hansen, Alex; O'Rourke, B; Manificat, G

    2004-03-01

    Self-affine dehydrated colloidal deposits on fresh mica surfaces of the synthetic layered silicate 2:1 smectite clay laponite have been studied by means of atomic force microscopy (AFM). AFM images of these prepared assemblies of sol and gel aggregates have been analyzed both by means of standard AFM Fourier software and a wavelet method. The deposited surfaces show a persistence to antipersistent crossover with a clay concentration dependent crossover length. It is concluded that the crossover length is associated with aggregate size, and further that the persistent roughness at small length scales signals near compact clusters of fractal dimension three, whereas the antipersistent roughness at large length scales signals a sedimentation process.

  16. Self-affine crossover length in a layered silicate deposit

    NASA Astrophysics Data System (ADS)

    Fossum, J. O.; Bergene, H. H.; Hansen, Alex; O'Rourke, B.; Manificat, G.

    2004-03-01

    Self-affine dehydrated colloidal deposits on fresh mica surfaces of the synthetic layered silicate 2:1 smectite clay laponite have been studied by means of atomic force microscopy (AFM). AFM images of these prepared assemblies of sol and gel aggregates have been analyzed both by means of standard AFM Fourier software and a wavelet method. The deposited surfaces show a persistence to antipersistent crossover with a clay concentration dependent crossover length. It is concluded that the crossover length is associated with aggregate size, and further that the persistent roughness at small length scales signals near compact clusters of fractal dimension three, whereas the antipersistent roughness at large length scales signals a sedimentation process.

  17. Effects of crossover hydrogen on platinum dissolution and agglomeration

    NASA Astrophysics Data System (ADS)

    Cheng, Tommy T. H.; Rogers, Erin; Young, Alan P.; Ye, Siyu; Colbow, Vesna; Wessel, Silvia

    2011-10-01

    The durability of catalysts in the polymer-electrolyte membrane fuel cell (PEMFC) is identified as a critical limiting factor for wide commercialization of fuel cells. Even though much progress has been made in understanding the degradation mechanisms, the phenomena of Pt dissolution and agglomeration and their contributing factors are not fully understood. In the present investigation, the effects of crossover hydrogen on Pt degradation are studied using an accelerated stress test (AST). The end-of-test (EOT) membrane-electrode-assemblies (MEAs) were characterized by X-ray diffraction (XRD), scanning-electron microscopy (SEM), and energy-dispersive X-ray (EDX). The results provided mechanistic understanding of Pt dissolution and agglomeration: Pt growth and agglomeration were found to be less severe with more crossover hydrogen due likely to the chemical reduction of Pt oxides by crossover hydrogen and the subsequently decrease in the amount of Pt ions formed via the oxide pathway.

  18. The Distribution of Crossovers along Unreplicated Lambda Bacteriophage Chromosomes

    PubMed Central

    Stahl, Franklin W.; McMilin, Kenneth D.; Stahl, Mary M.; Crasemann, Jean M.; Lam, Stephen

    1974-01-01

    The distribution of crossovers along unreplicated chromosomes of bacteriophage lambda has been examined by determining the density distributions and genotypes of particles in the progenies of crosses of density-labeled by ordinary parents in the presence of genetic blocks to replication. The Red and Rec systems combined produce crossovers primarily near the ends (especially the right end) of the chromosome. Removal of the generalized lambda recombination functions by red and gam mutations results in loss of these terminal crossovers; coupled with this loss is a disappearance of the differential dependence of recombination frequencies in terminal and central intervals on DNA synthesis. Removal of the bacterial system by a recA mutation results in severe depression of crossing over among unreplicated phage, with the few recombinants produced by the lambda system occurring near the right end. PMID:4416166

  19. Dimensional crossover of the dephasing time in disordered mesoscopic rings

    NASA Astrophysics Data System (ADS)

    Treiber, M.; Yevtushenko, O. M.; Marquardt, F.; von Delft, J.; Lerner, I. V.

    2009-11-01

    We study dephasing by electron interactions in a small disordered quasi-one-dimensional (1D) ring weakly coupled to leads. We use an influence functional for quantum Nyquist noise to describe the crossover for the dephasing time τφ(T) from diffusive or ergodic 1D (τφ-1∝T2/3,T1) to zero-dimensional (0D) behavior (τφ-1∝T2) as T drops below the Thouless energy. The crossover to 0D, predicted earlier for two-dimensional and three-dimensional systems, has so far eluded experimental observation. The ring geometry holds promise of meeting this long-standing challenge, since the crossover manifests itself not only in the smooth part of the magnetoconductivity but also in the amplitude of Altshuler-Aronov-Spivak oscillations. This allows signatures of dephasing in the ring to be cleanly extracted by filtering out those of the leads.

  20. Surface-environment effects in spin crossover solids

    NASA Astrophysics Data System (ADS)

    Gudyma, Iu.; Maksymov, A.

    2017-06-01

    The impact of surface effects on thermal induced spin crossover phenomenon is a subject of a broad and current interest. Using the modified Ising-like model of spin crossover solids with the ligand field as function of the molecule' positions and random component on surface by means of Metropolis Monte Carlo algorithm the thermal spin transition curves were calculated. The analysis of spin configuration during transition gives a general idea about contribution of molecules from the surface and inside the lattice into resulting magnetization of the systems. The behavior of hysteresis loop for various surface coupling and fluctuations strength has been described.

  1. Investigating dirty crossover through fidelity susceptibility and density of states

    NASA Astrophysics Data System (ADS)

    Khan, Ayan; Basu, Saurabh; Tanatar, B.

    2014-03-01

    We investigate the BCS-BEC crossover in an ultracold atomic gas in the presence of disorder. The disorder is incorporated in the mean-field formalism through Gaussian fluctuations. We observe evolution to an asymmetric line-shape of fidelity susceptibility (FS) as a function of interaction coupling with increasing disorder strength which may point to an impending quantum phase transition (QPT). The asymmetric line-shape is further analyzed using the statistical tools of skewness and kurtosis. We extend our analysis to density of states (DOS) for a better understanding of the crossover in the disordered environment.

  2. Fractal-to-nonfractal crossover for viscous fingers

    NASA Astrophysics Data System (ADS)

    Lee, Jysoo; Coniglio, Antonio; Stanley, H. Eugene

    1990-04-01

    We propose a position-space renormalization-group approach to the problem of viscous fingering in the absence of surface tension, with arbitrary viscosity ratio between the injected and displaced fluid. We find there are only two fixed points, the Eden and the diffusion-limited aggregation (DLA) points. The Eden point, which corresponds to a compact cluster with nonfractal surface, is stable in all directions, while the DLA fixed point is a saddle point. Hence if the viscosity of the injected fluid is not zero, the system must eventually cross over to a compact cluster. We also calculate the crossover exponent φ and crossover radius R×, and discuss possible experimental measurements.

  3. Stochastic resonance in photo-switchable spin-crossover solids

    NASA Astrophysics Data System (ADS)

    Gudyma, Iurii; Maksymov, Artur

    2017-07-01

    The stochastic kinetic in photo-switchable spin-crossover materials with periodic driving force in the context of stochastic resonance (SR) was studied. The resonance phenomena in spin-crossover system have been analyzed by means of spectral power amplification (SPA) function. The influence of the parameters of harmonic signal (amplitude and frequency) together with changes of noise intensity have been considered. The SPA is characterized by double peak curve with qualitatively different mechanisms of amplification of the peaks and is examined by Fourier analysis.

  4. With practice, keyboard shortcuts become faster than menu selection: A crossover interaction.

    PubMed

    Remington, Roger W; Yuen, Ho Wang Holman; Pashler, Harold

    2016-03-01

    It is widely believed that a graphical user interface (GUI) is superior to a command line interface (CLI) for novice users, but less efficient than the CLI after practice. However, there appears to be no detailed study of the crossover interaction that this implies. The rate of learning may shed light on the reluctance of experienced users to adopt keyboard shortcuts, even though, when mastered, shortcut use would reduce task completion times. We report 2 experiments examining changes in the efficiency of and preference for keyboard input versus GUI with practice. Experiment 1 had separate groups of subjects make speeded choice responses to words on a 20-item list either by clicking on a tab in a dropdown menu (GUI version) or by entering a preassigned keystroke combination (CLI version). The predicted crossover was observed after approximately 200 responses. Experiment 2 showed that following training all but 1 subject in the CLI-trained group chose to continue using shortcuts. These results suggest that frequency of shortcut use is a function of ease of retrieval, which develops over the course of multiple repetitions of the command. We discuss possible methods for promoting shortcut learning and the practical implications of our results.

  5. Hidden crossover phenomena in strongly Pauli-limited multiband superconductors: Application to CeCu2Si2

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Yasumasa; Machida, Kazushige; Ichioka, Masanori

    2015-07-01

    Motivated by recent experiments on heavy fermion materials CeCu2Si2 and UBe13, we develop a framework to capture generic properties of multiband superconductors with strong Pauli paramagnetic effect (PPE). In contrast to the single band case, the upper critical field Hc 2 can remain a second-order transition even for strong PPE cases. The expected first-order transition is hidden inside Hc 2 and becomes a crossover due to the interplay of multibandness. The present theory based on full self-consistent solutions of the microscopic Eilenberger theory explains several mysterious anomalies associated with the crossover and the "empty" vortex core state which is observed by recent STM experiment on CeCu2Si2 .

  6. Fluorescent Arabidopsis tetrads: a visual assay for quickly developing large crossover and crossover interference data sets.

    PubMed

    Berchowitz, Luke E; Copenhaver, Gregory P

    2008-01-01

    In most organisms, one crossover (CO) event inhibits the chances of another nearby event. The term used to describe this phenomenon is 'CO interference'. Here, we describe a protocol for quickly generating large data sets that are amenable to CO interference analysis in the flowering plant, Arabidopsis thaliana. We employ a visual assay that utilizes transgenic marker constructs encoding pollen-expressed fluorescent proteins of three colors in the quartet mutant background. In this genetic background, male meiotic products--the pollen grains--remain physically attached thereby facilitating tetrad analysis. We have developed a library of mapped marker insertions that, when crossed together, create adjacent intervals that can be rapidly and simultaneously screened for COs. This assay system is capable of detecting and differentiating single COs as well as two-, three- and four-strand double COs. We also describe how to analyze the data that are produced by this method. To generate and score a double interval in a wild-type and mutant background using this protocol will take 22-27 weeks.

  7. Phosphorylation of the Synaptonemal Complex Protein Zip1 Regulates the Crossover/Noncrossover Decision during Yeast Meiosis.

    PubMed

    Chen, Xiangyu; Suhandynata, Ray T; Sandhu, Rima; Rockmill, Beth; Mohibullah, Neeman; Niu, Hengyao; Liang, Jason; Lo, Hsiao-Chi; Miller, Danny E; Zhou, Huilin; Börner, G Valentin; Hollingsworth, Nancy M

    2015-12-01

    Interhomolog crossovers promote proper chromosome segregation during meiosis and are formed by the regulated repair of programmed double-strand breaks. This regulation requires components of the synaptonemal complex (SC), a proteinaceous structure formed between homologous chromosomes. In yeast, SC formation requires the "ZMM" genes, which encode a functionally diverse set of proteins, including the transverse filament protein, Zip1. In wild-type meiosis, Zmm proteins promote the biased resolution of recombination intermediates into crossovers that are distributed throughout the genome by interference. In contrast, noncrossovers are formed primarily through synthesis-dependent strand annealing mediated by the Sgs1 helicase. This work identifies a conserved region on the C terminus of Zip1 (called Zip1 4S), whose phosphorylation is required for the ZMM pathway of crossover formation. Zip1 4S phosphorylation is promoted both by double-strand breaks (DSBs) and the meiosis-specific kinase, MEK1/MRE4, demonstrating a role for MEK1 in the regulation of interhomolog crossover formation, as well as interhomolog bias. Failure to phosphorylate Zip1 4S results in meiotic prophase arrest, specifically in the absence of SGS1. This gain of function meiotic arrest phenotype is suppressed by spo11Δ, suggesting that it is due to unrepaired breaks triggering the meiotic recombination checkpoint. Epistasis experiments combining deletions of individual ZMM genes with sgs1-md zip1-4A indicate that Zip1 4S phosphorylation functions prior to the other ZMMs. These results suggest that phosphorylation of Zip1 at DSBs commits those breaks to repair via the ZMM pathway and provides a mechanism by which the crossover/noncrossover decision can be dynamically regulated during yeast meiosis.

  8. Phosphorylation of the Synaptonemal Complex Protein Zip1 Regulates the Crossover/Noncrossover Decision during Yeast Meiosis

    PubMed Central

    Chen, Xiangyu; Suhandynata, Ray T.; Sandhu, Rima; Rockmill, Beth; Mohibullah, Neeman; Niu, Hengyao; Liang, Jason; Lo, Hsiao-Chi; Miller, Danny E.; Zhou, Huilin; Börner, G. Valentin; Hollingsworth, Nancy M.

    2015-01-01

    Interhomolog crossovers promote proper chromosome segregation during meiosis and are formed by the regulated repair of programmed double-strand breaks. This regulation requires components of the synaptonemal complex (SC), a proteinaceous structure formed between homologous chromosomes. In yeast, SC formation requires the “ZMM” genes, which encode a functionally diverse set of proteins, including the transverse filament protein, Zip1. In wild-type meiosis, Zmm proteins promote the biased resolution of recombination intermediates into crossovers that are distributed throughout the genome by interference. In contrast, noncrossovers are formed primarily through synthesis-dependent strand annealing mediated by the Sgs1 helicase. This work identifies a conserved region on the C terminus of Zip1 (called Zip1 4S), whose phosphorylation is required for the ZMM pathway of crossover formation. Zip1 4S phosphorylation is promoted both by double-strand breaks (DSBs) and the meiosis-specific kinase, MEK1/MRE4, demonstrating a role for MEK1 in the regulation of interhomolog crossover formation, as well as interhomolog bias. Failure to phosphorylate Zip1 4S results in meiotic prophase arrest, specifically in the absence of SGS1. This gain of function meiotic arrest phenotype is suppressed by spo11Δ, suggesting that it is due to unrepaired breaks triggering the meiotic recombination checkpoint. Epistasis experiments combining deletions of individual ZMM genes with sgs1-md zip1-4A indicate that Zip1 4S phosphorylation functions prior to the other ZMMs. These results suggest that phosphorylation of Zip1 at DSBs commits those breaks to repair via the ZMM pathway and provides a mechanism by which the crossover/noncrossover decision can be dynamically regulated during yeast meiosis. PMID:26682552

  9. Locking and Unlocking the Molecular Spin Crossover Transition.

    PubMed

    Zhang, Xin; Costa, Paulo S; Hooper, James; Miller, Daniel P; N'Diaye, Alpha T; Beniwal, Sumit; Jiang, Xuanyuan; Yin, Yuewei; Rosa, Patrick; Routaboul, Lucie; Gonidec, Mathieu; Poggini, Lorenzo; Braunstein, Pierre; Doudin, Bernard; Xu, Xiaoshan; Enders, Axel; Zurek, Eva; Dowben, Peter A

    2017-08-28

    The Fe(II) spin crossover complex [Fe{H2 B(pz)2 }2 (bipy)] (pz = pyrazol-1-yl, bipy = 2,2'-bipyridine) can be locked in a largely low-spin-state configuration over a temperature range that includes temperatures well above the thermal spin crossover temperature of 160 K. This locking of the spin state is achieved for nanometer thin films of this complex in two distinct ways: through substrate interactions with dielectric substrates such as SiO2 and Al2 O3 , or in powder samples by mixing with the strongly dipolar zwitterionic p-benzoquinonemonoimine C6 H2 (-⋯ NH2 )2 (-⋯ O)2 . Remarkably, it is found in both cases that incident X-ray fluences then restore the [Fe{H2 B(pz)2 }2 (bipy)] moiety to an electronic state characteristic of the high spin state at temperatures of 200 K to above room temperature; that is, well above the spin crossover transition temperature for the pristine powder, and well above the temperatures characteristic of light- or X-ray-induced excited-spin-state trapping. Heating slightly above room temperature allows the initial locked state to be restored. These findings, supported by theory, show how the spin crossover transition can be manipulated reversibly around room temperature by appropriate design of the electrostatic and chemical environment. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. 50 CFR 660.120 - Trawl fishery-crossover provisions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Trawl fishery-crossover provisions. 660.120 Section 660.120 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OFF WEST COAST STATES West...

  11. Academic Crossover Study, University of Hawaii Community Colleges, Fall 1999.

    ERIC Educational Resources Information Center

    Hawaii Univ., Honolulu. Office of the Chancellor for Community Colleges.

    The academic crossover study was developed to answer two questions: (1) What is the course-taking pattern of the different groups of academic majors? (e.g. what is proportion of academic load taken outside the major); and (2) What is the client-serving pattern of the different subject disciplines? (e.g. what are the groups of students served by…

  12. Design and analysis of crossover trials for absorbing binary endpoints.

    PubMed

    Nason, Martha; Follmann, Dean

    2010-09-01

    The crossover is a popular and efficient trial design used in the context of patient heterogeneity to assess the effect of treatments that act relatively quickly and whose benefit disappears with discontinuation. Each patient can serve as her own control as within-individual treatment and placebo responses are compared. Conventional wisdom is that these designs are not appropriate for absorbing binary endpoints, such as death or HIV infection. We explore the use of crossover designs in the context of these absorbing binary endpoints and show that they can be more efficient than the standard parallel group design when there is heterogeneity in individuals' risks. We also introduce a new two-period design where first period "survivors" are rerandomized for the second period. This design combines the crossover design with the parallel design and achieves some of the efficiency advantages of the crossover design while ensuring that the second period groups are comparable by randomization. We discuss the validity of the new designs and evaluate both a mixture model and a modified Mantel-Haenszel test for inference. The mixture model assumes no carryover or period effects while the Mantel-Haenszel approach conditions out period effects. Simulations are used to compare the different designs and an example is provided to explore practical issues in implementation.

  13. Crossover Improvement for the Genetic Algorithm in Information Retrieval.

    ERIC Educational Resources Information Center

    Vrajitoru, Dana

    1998-01-01

    In information retrieval (IR), the aim of genetic algorithms (GA) is to help a system to find, in a huge documents collection, a good reply to a query expressed by the user. Analysis of phenomena seen during the implementation of a GA for IR has led to a new crossover operation, which is introduced and compared to other learning methods.…

  14. Crossover Improvement for the Genetic Algorithm in Information Retrieval.

    ERIC Educational Resources Information Center

    Vrajitoru, Dana

    1998-01-01

    In information retrieval (IR), the aim of genetic algorithms (GA) is to help a system to find, in a huge documents collection, a good reply to a query expressed by the user. Analysis of phenomena seen during the implementation of a GA for IR has led to a new crossover operation, which is introduced and compared to other learning methods.…

  15. The critical crossover at the n-hexane-water interface

    SciTech Connect

    Tikhonov, A. M.

    2010-06-15

    According to estimates of the parameters of the critical crossover in monolayers of long-chain alcohol molecules adsorbed at the n-hexane-water interface, all systems in which this phenomenon is observed are characterized by the same value of the critical exponent {nu} {approx} 1.8.

  16. Estimating crossover frequencies and testing for numerical interference with highly polymorphic markers

    SciTech Connect

    Ott, J.

    1996-12-31

    Interference maybe viewed as having two aspects, numerical interference referring to the numbers of crossovers occurring, and positional interference referring to the positions of crossovers. Here, the focus is on numerical interference and on methods of testing for its presence. A dense map of highly polymorphic markers is assumed so that each crossover can be observed. General relationships are worked out between crossover distributions and underlying chiasma distributions. It is shown that crossover distributions may be invalid, and methods are developed to estimate valid crossover distributions from observed counts of crossovers. Based on valid estimates of crossover distributions, tests for interference and development of empirical map functions are outlined. The methods are applied to published data on human chromosomes 9 and 19. 16 refs., 1 fig., 3 tabs.

  17. Crossover and thermodynamic representation in the extended η model for fractal growth

    NASA Astrophysics Data System (ADS)

    Nagatani, Takashi; Stanley, H. Eugene

    1990-10-01

    The η model for the dielectric breakdown is extended to the case where double power laws apply. It is shown that a crossover phenomenon between the diffusion-limited aggregation (DLA) fractal and the η fractal occurs in the extended η model. Through the use of the dimensional analysis, a dimensionless parameter is found to govern the crossover. It is shown that when η<1 the crossover from the DLA fractal to the η fractal occurs with increasing size, and if η>1 the inverse crossover from the η fractal to the DLA fractal appears. It is also shown that the crossover radius is controlled by changing the applied field. The global flow diagram in the two-parameter space is obtained by using a two-parameter position-space renormalization-group approach. The crossover exponent and the crossover radius are calculated. The crossover phenomenon is described in terms of a thermodynamic representation of the two-phase equilibrium.

  18. Geodetic constraints from multi-beam laser altimeter crossovers

    NASA Astrophysics Data System (ADS)

    Mazarico, Erwan; Neumann, G. A.; Rowlands, D. D.; Smith, D. E.

    2010-06-01

    The round-trip travel time measurements made by spacecraft laser altimeters are primarily used to construct topographic maps of the target body. The accuracy of the calculated bounce point locations of the laser pulses depends on the quality of the spacecraft trajectory reconstruction. The trajectory constraints from Doppler and range radio tracking data can be supplemented by altimetric “crossovers”, to greatly improve the reconstruction of the spacecraft trajectory. Crossovers have been used successfully in the past (e.g., Mars Orbiter Laser Altimeter on Mars Global Surveyor), but only with single-beam altimeters. The same algorithms can be used with a multi-beam laser altimeter, but we present a method using the unique cross-track topographic information present in the multi-beam data. Those crossovers are especially adapted to shallow (small angle) intersections, as the overlapping area is large, reducing the inherent ambiguities of single-beam data in that situation. We call those “swath crossovers”. They prove particularly useful in the case of polar-orbiting spacecraft over slowly rotating bodies, because all the non-polar crossovers have small intersection angles. To demonstrate this method, we perform a simplified simulation based on the Lunar Reconnaissance Orbiter (LRO) and its five-beam Lunar Orbiter Laser Altimeter. We show that swath crossovers over one lunar month can independently, from geometry alone, recover the imposed orbital perturbations with great accuracy (5 m horizontal, < 1 m vertical, about one order of magnitude smaller than the imposed perturbations). We also present new types of constraints that can be derived from the swath crossovers, and designed to be used in a precision orbit determination setup. In future work, we will use such multi-beam altimetric constraints with data from LRO.

  19. Gene Conversion Tracts Associated with Crossovers in Rhizobium etli

    PubMed Central

    Santoyo, Gustavo; Martínez-Salazar, Jaime M.; Rodríguez, César; Romero, David

    2005-01-01

    Gene conversion has been defined as the nonreciprocal transfer of information between homologous sequences. Despite its broad interest for genome evolution, the occurrence of this mechanism in bacteria has been difficult to ascertain due to the possible occurrence of multiple crossover events that would mimic gene conversion. In this work, we employ a novel system, based on cointegrate formation, to isolate gene conversion events associated with crossovers in the nitrogen-fixing bacterium Rhizobium etli. In this system, selection is applied only for cointegrate formation, with gene conversions being detected as unselected events. This minimizes the likelihood of multiple crossovers. To track the extent and architecture of gene conversions, evenly spaced nucleotide changes were made in one of the nitrogenase structural genes (nifH), introducing unique sites for different restriction endonucleases. Our results show that (i) crossover events were almost invariably accompanied by a gene conversion event occurring nearby; (ii) gene conversion events ranged in size from 150 bp to 800 bp; (iii) gene conversion events displayed a strong bias, favoring the preservation of incoming sequences; (iv) even small amounts of sequence divergence had a strong effect on recombination frequency; and (v) the MutS mismatch repair system plays an important role in determining the length of gene conversion segments. A detailed analysis of the architecture of the conversion events suggests that multiple crossovers are an unlikely alternative for their generation. Our results are better explained as the product of true gene conversions occurring under the double-strand break repair model for recombination. PMID:15937174

  20. Altered Crossover Distribution and Frequency in Spermatocytes of Infertile Men with Azoospermia

    PubMed Central

    Ren, He; Ferguson, Kyle; Kirkpatrick, Gordon; Vinning, Tanya; Chow, Victor; Ma, Sai

    2016-01-01

    During meiosis, homologous chromosomes pair to facilitate the exchange of DNA at crossover sites along the chromosomes. The frequency and distribution of crossover formation are tightly regulated to ensure the proper progression of meiosis. Using immunofluorescence techniques, our group and others have studied the meiotic proteins in spermatocytes of infertile men, showing that this population displays a reduced frequency of crossovers compared to fertile men. An insufficient number of crossovers is thought to promote chromosome missegregation, in which case the faulty cell may face meiotic arrest or contribute to the production of aneuploid sperm. Increasing evidence in model organisms has suggested that the distribution of crossovers may also be important for proper chromosome segregation. In normal males, crossovers are shown to be rare near centromeres and telomeres, while frequent in subtelomeric regions. Our study aims to characterize the crossover distribution in infertile men with non-obstructive (NOA) and obstructive azoospermia (OA) along chromosomes 13, 18 and 21. Eight of the 16 NOA men and five of the 21 OA men in our study displayed reduced crossover frequency compared to control fertile men. Seven NOA men and nine OA men showed altered crossover distributions on at least one of the chromosome arms studied compared to controls. We found that although both NOA and OA men displayed altered crossover distributions, NOA men may be at a higher risk of suffering both altered crossover frequencies and distributions compared to OA men. Our data also suggests that infertile men display an increase in crossover formation in regions where they are normally inhibited, specifically near centromeres and telomeres. Finally, we demonstrated a decrease in crossovers near subtelomeres, as well as increased average crossover distance to telomeres in infertile men. As telomere-guided mechanisms are speculated to play a role in crossover formation in subtelomeres, future

  1. 50 CFR 660.320 - Open access fishery-crossover provisions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Open access fishery-crossover provisions... West Coast Groundfish-Open Access Fisheries § 660.320 Open access fishery—crossover provisions. The crossover provisions listed at § 660.60(h)(7), apply to vessels fishing in the open access fishery. ...

  2. 50 CFR 660.320 - Open access fishery-crossover provisions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Open access fishery-crossover provisions... West Coast Groundfish-Open Access Fisheries § 660.320 Open access fishery—crossover provisions. The crossover provisions listed at § 660.60(h)(7), apply to vessels fishing in the open access fishery. ...

  3. 50 CFR 660.320 - Open access fishery-crossover provisions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Open access fishery-crossover provisions... West Coast Groundfish-Open Access Fisheries § 660.320 Open access fishery—crossover provisions. The crossover provisions listed at § 660.60(h)(7), apply to vessels fishing in the open access fishery. ...

  4. What's Mine Is Yours: The Crossover of Day-Specific Self-Esteem

    ERIC Educational Resources Information Center

    Neff, Angela; Sonnentag, Sabine; Niessen, Cornelia; Unger, Dana

    2012-01-01

    This diary study examines the daily crossover of self-esteem within working couples. By integrating self-esteem research into the crossover framework, we hypothesized that the day-specific self-esteem experienced by one partner after work crosses over to the other partner. Furthermore, we proposed that this daily crossover process is moderated by…

  5. What's Mine Is Yours: The Crossover of Day-Specific Self-Esteem

    ERIC Educational Resources Information Center

    Neff, Angela; Sonnentag, Sabine; Niessen, Cornelia; Unger, Dana

    2012-01-01

    This diary study examines the daily crossover of self-esteem within working couples. By integrating self-esteem research into the crossover framework, we hypothesized that the day-specific self-esteem experienced by one partner after work crosses over to the other partner. Furthermore, we proposed that this daily crossover process is moderated by…

  6. The crossover toe and valgus toe deformity.

    PubMed

    Sferra, James; Arndt, Steven

    2011-12-01

    Second toe problems are among the most common of all forefoot complaints. Its proximity to the hallux combined with limited motion at the second tarsometatarsal joint likely contributes to the second MTP joint being the most common to experience both pain and deformity. Many causes have been linked to this problem, which has lead to many surgical techniques to correct this deformity. Although many techniques have been described, a systematic approach relying first on soft tissue releases and plication followed by osteotomies as necessary has lead to satisfactory outcomes in the treatment of this difficult problem.

  7. Audiovisual distraction for pain relief in paediatric inpatients: A crossover study.

    PubMed

    Oliveira, N C A C; Santos, J L F; Linhares, M B M

    2017-01-01

    Pain is a stressful experience that can have a negative impact on child development. The aim of this crossover study was to examine the efficacy of audiovisual distraction for acute pain relief in paediatric inpatients. The sample comprised 40 inpatients (6-11 years) who underwent painful puncture procedures. The participants were randomized into two groups, and all children received the intervention and served as their own controls. Stress and pain-catastrophizing assessments were initially performed using the Child Stress Scale and Pain Catastrophizing Scale for Children, with the aim of controlling these variables. The pain assessment was performed using a Visual Analog Scale and the Faces Pain Scale-Revised after the painful procedures. Group 1 received audiovisual distraction before and during the puncture procedure, which was performed again without intervention on another day. The procedure was reversed in Group 2. Audiovisual distraction used animated short films. A 2 × 2 × 2 analysis of variance for 2 × 2 crossover study was performed, with a 5% level of statistical significance. The two groups had similar baseline measures of stress and pain catastrophizing. A significant difference was found between periods with and without distraction in both groups, in which scores on both pain scales were lower during distraction compared with no intervention. The sequence of exposure to the distraction intervention in both groups and first versus second painful procedure during which the distraction was performed also significantly influenced the efficacy of the distraction intervention. Audiovisual distraction effectively reduced the intensity of pain perception in paediatric inpatients. The crossover study design provides a better understanding of the power effects of distraction for acute pain management. Audiovisual distraction was a powerful and effective non-pharmacological intervention for pain relief in paediatric inpatients. The effects were

  8. The effects of mismatch repair and RAD1 genes on interchromosomal crossover recombination in Saccharomyces cerevisiae.

    PubMed

    Nicholson, Ainsley; Fabbri, Rebecca M; Reeves, Jason W; Crouse, Gray F

    2006-06-01

    We have previously shown that recombination between 400-bp substrates containing only 4-bp differences, when present in an inverted repeat orientation, is suppressed by >20-fold in wild-type strains of S. cerevisiae. Among the genes involved in this suppression were three genes involved in mismatch repair--MSH2, MSH3, and MSH6--and one in nucleotide excision repair, RAD1. We now report the involvement of these genes in interchromosomal recombination occurring via crossovers using these same short substrates. In these experiments, recombination was stimulated by a double-strand break generated by the HO endonuclease and can occur between completely identical (homologous) substrates or between nonidentical (homeologous) substrates. In addition, a unique feature of this system is that recombining DNA strands can be given a choice of either type of substrate. We find that interchromosomal crossover recombination with these short substrates is severely inhibited in the absence of MSH2, MSH3, or RAD1 and is relatively insensitive to the presence of mismatches. We propose that crossover recombination with these short substrates requires the products of MSH2, MSH3, and RAD1 and that these proteins have functions in recombination in addition to the removal of terminal nonhomology. We further propose that the observed insensitivity to homeology is a result of the difference in recombinational mechanism and/or the timing of the observed recombination events. These results are in contrast with those obtained using longer substrates and may be particularly relevant to recombination events between the abundant short repeated sequences that characterize the genomes of higher eukaryotes.

  9. Using scratch card technology for random allocation concealment in a clinical trial with a crossover design.

    PubMed

    Beksinska, Mags E; Joanis, Carol; Smit, Jenni A; Pienaar, Jacqueline; Piaggio, Gilda

    2013-02-01

    To avoid selection bias in clinical trials, random allocation concealment is crucial to ensure that participants and or researchers remain unaware of assignments. We aimed to design an allocation concealment method that reduced the possibility of selection bias for a randomized, open-label, crossover trial to evaluate device function of four female condom (FC) types. Using scratch card technology, we devised a simple method of concealment, whereby the treatment sequence was printed on a single card for each participant, and the codes for each treatment in the sequence were concealed beneath foil squares on a stiff A6-sized card. On the first and subsequent follow-up visits, the foil corresponding to that visit was scratched from the square to reveal the condom type allocation for the next condom-use period. Staff in the South African and Chinese trial sites were trained in use and care of the card, and on completion of the study completed a questionnaire on their experience of use. Research staff in both countries found the card easy to use and those who had previously used the sequentially numbered, opaque, sealed envelopes (SNOSE) system for random allocation reported the scratch card easier to use. Research staff most commonly used a coin to remove the foil square and some used their fingernails. In both South Africa and China, no errors in allocation sequence were found during study monitoring. Scratch card system of allocation cannot be printed in-house. This novel, effective method of concealment for a crossover random allocation was well liked by study staff. The most important advantage of this method is the ability to conceal consecutive allocations of a crossover design using a single card, thus eliminating the need for multiple envelopes per participant. While we used this method in a clinical trial of FCs, it could be employed in a range of other clinical trials and other randomized studies.

  10. Skating crossovers on a motorized flywheel: a preliminary experimental design to test effect on speed and on crossovers.

    PubMed

    Smith, Aynsley M; Krause, David A; Stuart, Michael J; Montelpare, William J; Sorenson, Matthew C; Link, Andrew A; Gaz, Daniel V; Twardowski, Casey P; Larson, Dirk R; Stuart, Michael B

    2013-12-01

    Ice hockey requires frequent skater crossovers to execute turns. Our investigation aimed to determine the effectiveness of training crossovers on a motorized, polyethylene high-resistance flywheel. We hypothesized that high school hockey players training on the flywheel would perform as well as their peers training on ice. Participants were 23 male high-school hockey players (age 15-19 years). The study used an experimental prospective design to compare players who trained for 9 sessions on the 22-foot flywheel with players who trained for 9 sessions on a similarly sized on-ice circle. Both groups were compared with control subjects who were randomly selected from the same participant pool as those training on ice. All players were tested before and after their 3-week training regimens, and control subjects were asked to not practice crossovers between testing. Group 1 trained in a hockey training facility housing the flywheel, and group 2 trained in the ice hockey arena where testing occurred. Primary outcome measures tested in both directions were: (a) speed (time in seconds) required to skate crossovers for 3 laps of a marked face-off circle, (b) cadence of skating crossovers on the similarly sized circles, and (c) a repeat interval speed test, which measures anaerobic power. No significant changes were found between groups in on-ice testing before and after training. Among the group 1 players, 7 of 8 believed they benefited from flywheel training. Group 2 players, who trained on ice, did not improve performance significantly over group 1 players. Despite the fact that no significant on-ice changes in performance were observed in objective measures, players who trained on the flywheel subjectively reported that the flywheel is an effective cost-effective alternative to training on ice. This is a relevant finding when placed in context with limited availability of on-ice training.

  11. Comparison of the Carbon System Parameters at the Global CO2 Survey Crossover Locations in the North and South Pacific Ocean, 1990-1996

    SciTech Connect

    Feely, Richard A; Lamb, Marilyn F.; Greeley, Dana J.; Wanninkhof, Rik

    1999-10-01

    As a collaborative program to measure global ocean carbon inventories and provide estimates of the anthropogenic carbon dioxide (C02) uptake by the oceans. the National Oceanic and Atmospheric Administration and the U.S. Department of Energy have sponsored the collection of ocean carbon measurements as part of the World Ocean Circulation Experiment and Ocean-Atmosphere Carbon Exchange Study cruises. The cruises discussed here occurred in the North and South Pacific from 1990 through 1996. The carbon parameters from these 30 crossover locations have been compared to ensure that a consistent global data set emerges from the survey cruises. !'he results indicate that for dissolved inorganic carbon. fugacity of C02• and pH. the a~:,rreements at most crossover locations are well within the design specifications for the global CO) survey: whereas. in the case of total alkaliniry. the agreement between crossover locations is not as close.

  12. Crossover-site sequence and DNA torsional stress control strand interchanges by the Bxb1 site-specific serine recombinase

    PubMed Central

    Keenholtz, Ross A.; Grindley, Nigel D.F.; Hatfull, Graham F.; Marko, John F.

    2016-01-01

    DNA segment exchange by site-specific serine recombinases (SRs) is thought to proceed by rigid-body rotation of the two halves of the synaptic complex, following the cleavages that create the two pairs of exchangeable ends. It remains unresolved how the amount of rotation occurring between cleavage and religation is controlled. We report single-DNA experiments for Bxb1 integrase, a model SR, where dynamics of individual synapses were observed, using relaxation of supercoiling to report on cleavage and rotation events. Relaxation events often consist of multiple rotations, with the number of rotations per relaxation event and rotation velocity sensitive to DNA sequence at the center of the recombination crossover site, torsional stress and salt concentration. Bulk and single-DNA experiments indicate that the thermodynamic stability of the annealed, but cleaved, crossover sites controls ligation efficiency of recombinant and parental synaptic complexes, regulating the number of rotations during a breakage-religation cycle. The outcome is consistent with a ‘controlled rotation’ model analogous to that observed for type IB topoisomerases, with religation probability varying in accord with DNA base-pairing free energies at the crossover site. Significantly, we find no evidence for a special regulatory mechanism favoring ligation and product release after a single 180° rotation. PMID:27550179

  13. Signatures of Fermion Pairing with Unconventional Symmetry Around the BCS-BEC Crossover in a Quasi-2D Lattice

    NASA Astrophysics Data System (ADS)

    Volčko, Dušan; Quader, Khandker F.

    2012-12-01

    We consider fermions on a 2D square lattice with a finite-range pairing interaction, and obtain signatures for unconventional pair-symmetry states, dx2-y2 and extended-s (s*), in the Bardeen-Cooper-Schrieffer-Bose-Einstein Condensation crossover region. We find that the fermion momentum distribution function, vk2, the ratio of the Bogoliubov coefficients, vk/uk, and the Fourier transform of vk2 are strikingly different for d and s* symmetries in the crossover region. The chemical potential and the gap functions for both pairing symmetries show several interesting features as a function of interaction. Fermionic atoms in 2D optical lattices may provide a way to test these signatures. We discuss current generation cold atom experiments that may be utilized.

  14. Two-dimensional metal-insulator transition as a strong localization induced crossover phenomenon

    NASA Astrophysics Data System (ADS)

    Das Sarma, S.; Hwang, E. H.

    2014-06-01

    classical percolation theory, concluding that experiments support the Ioffe-Regel criterion for the 2D MIT crossover phenomena.

  15. Effect of sex, age and genetics on crossover interference in cattle

    PubMed Central

    Wang, Zhiying; Shen, Botong; Jiang, Jicai; Li, Jinquan; Ma, Li

    2016-01-01

    Crossovers generated by homologous recombination ensure proper chromosome segregation during meiosis. Crossover interference results in chiasmata being more evenly distributed along chromosomes, but the mechanism underlying crossover interference remains elusive. Based on large pedigrees of Holstein and Jersey cattle with genotype data, we extracted three-generation families, including 147,327 male and 71,687 female meioses in Holstein, and 108,163 male and 37,008 female meioses in Jersey, respectively. We identified crossovers in these meioses and fitted the Housworth-Stahl “interference-escape” model to study crossover interference patterns in the cattle genome. Our result reveals that the degree of crossover interference is stronger in females than in males. We found evidence for inter-chromosomal variation in the level of crossover interference, with smaller chromosomes exhibiting stronger interference. In addition, crossover interference levels decreased with maternal age. Finally, sex-specific GWAS analyses identified one locus near the NEK9 gene on chromosome 10 to have a significant effect on crossover interference levels. This locus has been previously associated with recombination rate in cattle. Collectively, this large-scale analysis provided a comprehensive description of crossover interference across chromosome, sex and age groups, identified associated candidate genes, and produced useful insights into the mechanism of crossover interference. PMID:27892966

  16. Cascading dynamics on random networks: crossover in phase transition.

    PubMed

    Liu, Run-Ran; Wang, Wen-Xu; Lai, Ying-Cheng; Wang, Bing-Hong

    2012-02-01

    In a complex network, random initial attacks or failures can trigger subsequent failures in a cascading manner, which is effectively a phase transition. Recent works have demonstrated that in networks with interdependent links so that the failure of one node causes the immediate failures of all nodes connected to it by such links, both first- and second-order phase transitions can arise. Moreover, there is a crossover between the two types of transitions at a critical system-parameter value. We demonstrate that these phenomena can occur in the more general setting where no interdependent links are present. A heuristic theory is derived to estimate the crossover and phase-transition points, and a remarkable agreement with numerics is obtained.

  17. Cascading dynamics on random networks: Crossover in phase transition

    NASA Astrophysics Data System (ADS)

    Liu, Run-Ran; Wang, Wen-Xu; Lai, Ying-Cheng; Wang, Bing-Hong

    2012-02-01

    In a complex network, random initial attacks or failures can trigger subsequent failures in a cascading manner, which is effectively a phase transition. Recent works have demonstrated that in networks with interdependent links so that the failure of one node causes the immediate failures of all nodes connected to it by such links, both first- and second-order phase transitions can arise. Moreover, there is a crossover between the two types of transitions at a critical system-parameter value. We demonstrate that these phenomena can occur in the more general setting where no interdependent links are present. A heuristic theory is derived to estimate the crossover and phase-transition points, and a remarkable agreement with numerics is obtained.

  18. Hot Neutron Stars with Hadron-Quark Crossover

    NASA Astrophysics Data System (ADS)

    Masuda, Kota; Hatsuda, Tetsuo; Takatsuka, Tatsuyuki

    2016-12-01

    The effects of the hadron-quark crossover on the bulk properties of cold and hot neutron stars (NSs) are studied. We suggested a new phenomenological equation of state (EOS), which interpolates the two phases at around 3 times the nuclear matter density (ρ0), and found that the cold NSs with the gravitational mass larger than 2M⊙ can be sustained. This is in sharp contrast to the case of the first-order hadron-quark transition where the quark matter inevitably leads to soft EOS. The interpolated EOS is also generalized to the supernova matter at finite temperature to describe the hot NSs at birth. The hadron-quark crossover is found to decrease the central temperature of the hot NSs under isentropic condition due to the color degrees of freedom.

  19. Net baryon fluctuations from a crossover equation of state

    NASA Astrophysics Data System (ADS)

    Kapusta, J.; Albright, M.; Young, C.

    2016-08-01

    We have constructed an equation of state which smoothly interpolates between an excluded-volume hadron resonance gas at low energy density to a plasma of quarks and gluons at high energy density. This crossover equation of state agrees very well with lattice calculations at both zero and nonzero baryon chemical potential. We use it to compute the variance, skewness, and kurtosis of fluctuations of baryon number, and compare to measurements of proton number fluctuations in central Au-Au collisions as measured by the STAR Collaboration in a beam energy scan at the Relativistic Heavy-Ion Collider. The crossover equation of state can reproduce the data if the fluctuations are frozen out at temperatures well below than the average chemical freeze-out.

  20. 3D Framework DNA Origami with Layered Crossovers.

    PubMed

    Hong, Fan; Jiang, Shuoxing; Wang, Tong; Liu, Yan; Yan, Hao

    2016-10-04

    Designer DNA architectures with nanoscale geometric controls provide a programmable molecular toolbox for engineering complex nanodevices. Scaffolded DNA origami has dramatically improved our ability to design and construct DNA nanostructures with finite size and spatial addressability. Here we report a novel design strategy to engineer multilayered wireframe DNA structures by introducing crossover pairs that connect neighboring layers of DNA double helices. These layered crossovers (LX) allow the scaffold or helper strands to travel through different layers and can control the relative orientation of DNA helices in neighboring layers. Using this design strategy, we successfully constructed four versions of two-layer parallelogram structures with well-defined interlayer angles, a three-layer structure with triangular cavities, and a 9- and 15-layer square lattices. This strategy provides a general route to engineer 3D framework DNA nanostructures with controlled cavities and opportunities to design host-guest networks analogs to those produced with metal organic frameworks.

  1. Isospin Dependent Pairing Interactions and BCS-BEC crossover

    SciTech Connect

    Sagawa, H.; Margueron, J.; Hagino, K.

    2008-11-11

    We propose new types of density dependent contact pairing interaction which reproduce the pairing gaps in symmetric and neutron matters obtained by a microscopic treatment based on the realistic nucleon-nucleon interaction. The BCS-BEC crossover of neutrons pairs in symmetric and asymmetric nuclear matters is studied by using these contact interactions. It is shown that the bare and screened pairing interactions lead to different features of the BCS-BEC crossover in symmetric nuclear matter. We perform Hartree-Fock-Bogoliubov (HFB) calculations for semi-magic Calcium, Nickel, Tin and Lead isotopes and N = 20, 28, 50 and 82 isotones using these density-dependent pairing interactions. Our calculations well account for the experimental data for the neutron number dependence of binding energy, two neutrons separation energy, and odd-even mass staggering of these isotopes. Especially the interaction IS+IV Bare without the medium polarization effect gives satisfactory results for all the isotopes.

  2. Single-crossover recombination and ancestral recombination trees.

    PubMed

    Baake, Ellen; von Wangenheim, Ute

    2014-05-01

    We consider the Wright-Fisher model for a population of [Formula: see text] individuals, each identified with a sequence of a finite number of sites, and single-crossover recombination between them. We trace back the ancestry of single individuals from the present population. In the [Formula: see text] limit without rescaling of parameters or time, this ancestral process is described by a random tree, whose branching events correspond to the splitting of the sequence due to recombination. With the help of a decomposition of the trees into subtrees, we calculate the probabilities of the topologies of the ancestral trees. At the same time, these probabilities lead to a semi-explicit solution of the deterministic single-crossover equation. The latter is a discrete-time dynamical system that emerges from the Wright-Fisher model via a law of large numbers and has been waiting for a solution for many decades.

  3. A Bistable Microelectromechanical System Actuated by Spin-Crossover Molecules.

    PubMed

    Manrique-Juarez, Maria D; Mathieu, Fabrice; Shalabaeva, Victoria; Cacheux, Jean; Rat, Sylvain; Nicu, Liviu; Leïchlé, Thierry; Salmon, Lionel; Molnár, Gábor; Bousseksou, Azzedine

    2017-07-03

    We report on a bistable MEMS device actuated by spin-crossover molecules. The device consists of a freestanding silicon microcantilever with an integrated piezoresistive detection system, which was coated with a 140 nm thick film of the [Fe(HB(tz)3 )2 ] (tz=1,2,4-triazol-1-yl) molecular spin-crossover complex. Switching from the low-spin to the high-spin state of the ferrous ions at 338 K led to a reversible upward bending of the cantilever in agreement with the change in the lattice parameters of the complex. The strong mechanical coupling was also evidenced by the decrease of approximately 66 Hz in the resonance frequency in the high-spin state as well as by the drop in the quality factor around the spin transition. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Crossover behavior in hydrogen sensing mechanism for palladium ultrathin films.

    SciTech Connect

    Darling, S. B.; Ramanathan, M.; Skudlarek, G.; Wang, H. H.; Illinois Math and Science Academy

    2010-01-01

    Palladium has been extensively studied as a material for hydrogen sensors because of the simplicity of its reversible resistance change when exposed to hydrogen gas. Various palladium films and nanostructures have been used, and different responses have been observed with these diverse morphologies. In some cases, such as with nanowires, the resistance will decrease, whereas in others, such as with thick films, the resistance will increase. Each of these mechanisms has been explored for several palladium structures, but the crossover between them has not been systematically investigated. Here we report on a study aimed at deciphering the nanostructure-property relationships of ultrathin palladium films used as hydrogen gas sensors. The crossover in these films is observed at a thickness of {approx} 5 nm. Ramifications for future sensor developments are discussed.

  5. Assestment of correlations and crossover scale in electroseismic time series

    NASA Astrophysics Data System (ADS)

    Guzman-Vargas, L.; Ramírez-Rojas, A.; Angulo-Brown, F.

    2009-04-01

    Evaluating complex fluctuations in electroseismic time series is an important task not only for earthquake prediction but also for understanding complex processes related to earthquake preparation. Previous studies have reported alterations, as the emergence of correlated dynamics in geoelectric potentials prior to an important earthquake (EQ). In this work, we apply the detrended fluctuation analysis and introduce a statistical procedure to characterize the presence of crossovers in scaling exponents, to analyze the fluctuations of geoelectric time series monitored in two sites located in Mexico. We find a complex behavior characterized by the presence of a crossover in the correlation exponents in the vicinity of a M=7.4 EQ occurred on Sept. 14, 1995. Finally, we apply the t-student test to evaluate the level of significance between short and large scaling exponents.

  6. Chiral relaxation time at the crossover of quantum chromodynamics

    NASA Astrophysics Data System (ADS)

    Ruggieri, M.; Peng, G. X.; Chernodub, M.

    2016-09-01

    We study microscopic processes responsible for chirality flips in the thermal bath of quantum chromodynamics at finite temperature and zero baryon chemical potential. We focus on the temperature range where the crossover from chirally broken phase to quark-gluon plasma takes place, namely, T ≃(150 ,200 ) MeV . The processes we consider are quark-quark scatterings mediated by collective excitations with the quantum number of pions and σ meson; hence we refer to these processes simply as one-pion (one-σ ) exchanges. We use a Nambu-Jona-Lasinio model to compute equilibrium properties of the thermal bath, as well as the relevant scattering kernel to be used in the collision integral to estimate the chiral relaxation time τ . We find τ ≃0.1 ÷1 fm /c around the chiral crossover.

  7. Tuning the quantum critical crossover in quantum dots

    NASA Astrophysics Data System (ADS)

    Murthy, Ganpathy

    2005-03-01

    Quantum dots with large Thouless number g embody a regime where both disorder and interactions can be treated nonperturbatively using large-N techniques (with N=g) and quantum phase transitions can be studied. Here we focus on dots where the noninteracting Hamiltonian is drawn from a crossover ensemble between two symmetry classes, where the crossover parameter introduces a new, tunable energy scale independent of and much smaller than the Thouless energy. We show that the quantum critical regime, dominated by collective critical fluctuations, can be accessed at the new energy scale. The nonperturbative physics of this regime can only be described by the large-N approach, as we illustrate with two experimentally relevant examples. G. Murthy, PRB 70, 153304 (2004). G. Murthy, R. Shankar, D. Herman, and H. Mathur, PRB 69, 075321 (2004)

  8. Excitonic correlation in the Mott crossover regime in Ge

    NASA Astrophysics Data System (ADS)

    Sekiguchi, Fumiya; Shimano, Ryo

    2015-04-01

    Exciton Mott transition (EMT) in Ge was investigated by using optical-pump and terahertz-probe spectroscopy. From the quantitative analysis of optical conductivity and dielectric function, we evaluated the densities of unbound electron-hole pairs and excitons after the photoexcitation, from which we determined the ionization ratio of excitons α. The Mott crossover density region in Ge was elucidated from the density dependence of α in the temperature range above the critical temperature of electron-hole droplets. The 1 s -2 p excitonic transition energy hardly shifted with increasing density toward the EMT. Combined with the similar results recently observed in bulk Si, we suggest that the robustness of excitonic correlation against the Coulomb screening is a universal feature in bulk semiconductors in the Mott crossover regime.

  9. Dynamical Crossover in Complex Networks near the Percolation Transition

    NASA Astrophysics Data System (ADS)

    Kawasaki, Fumiya; Yakubo, Kousuke

    2011-10-01

    The return probability P0(t) of random walkers is investigated numerically for several scale-free fractal networks. Our results show that P0(t) is proportional to t-ds/2 with the non-integer spectral dimension ds as in the case of non-scale free fractal networks. We also study how the diffusion process is affected by the structural crossover from a fractal to a small-world architecture in a network near the percolation transition. It is elucidated that the corresponding dynamical crossover is scaled only by the unique characteristic time tξ regardless of whether the network is scale free or not. In addition, the scaling relation ds= 2Df/dw is found to be valid even for scale-free fractal networks, where Df and dw are the fractal and the walk dimensions. These results suggest that qualitative properties of P0(t) are irrelevant to the scale-free nature of networks.

  10. Dipole modes of a superfluid Bose-Fermi mixture in the BCS-BEC crossover

    NASA Astrophysics Data System (ADS)

    Wen, Wen; Chen, Bingyan; Zhang, Xuewu

    2017-02-01

    Motivated by the first experimental realization by the Ecole Normale Supérieure (ENS) group of a mixture of a Bose-Einstein condensate with a Fermi superfluid continuously changing from a Bardeen-Cooper-Schrieffer (BCS) superfluid to a Bose-Einstein condensate (BEC) (Ferrier-Barbut et al 2014 Science 345 1035), we analytically study the dipole modes of the superfluid Bose-Fermi mixture in the BCS-BEC crossover. The analytical approach can explicitly reveal relationships between the frequencies of the dipole modes and the microscopic properties of the novel system. We start from coupled hydrodynamic equations, where the equation of state for the Fermi superfluid in the crossover is an analytical fitting formula based on experimental data, and by using a scaling approach we analytically study eigenfrequencies of the dipole modes for the coupled system in the ENS experimental parameters. Without the boson-fermion interaction in the equilibrium density profiles, our theoretical results can be reduced to the mean-field model and is consistent with the experimental data. However, by further taking into account the boson-fermion interaction numerically and analytically, we find that the results disagree with the experiment, especially in the parameter regime where the boson interaction is smaller than the boson-fermion interaction.

  11. Crossovers are associated with mutation and biased gene conversion at recombination hotspots

    PubMed Central

    Arbeithuber, Barbara; Betancourt, Andrea J.; Ebner, Thomas; Tiemann-Boege, Irene

    2015-01-01

    Meiosis is a potentially important source of germline mutations, as sites of meiotic recombination experience recurrent double-strand breaks (DSBs). However, evidence for a local mutagenic effect of recombination from population sequence data has been equivocal, likely because mutation is only one of several forces shaping sequence variation. By sequencing large numbers of single crossover molecules obtained from human sperm for two recombination hotspots, we find direct evidence that recombination is mutagenic: Crossovers carry more de novo mutations than nonrecombinant DNA molecules analyzed for the same donors and hotspots. The observed mutations were primarily CG to TA transitions, with a higher frequency of transitions at CpG than non-CpGs sites. This enrichment of mutations at CpG sites at hotspots could predominate in methylated regions involving frequent single-stranded DNA processing as part of DSB repair. In addition, our data set provides evidence that GC alleles are preferentially transmitted during crossing over, opposing mutation, and shows that GC-biased gene conversion (gBGC) predominates over mutation in the sequence evolution of hotspots. These findings are consistent with the idea that gBGC could be an adaptation to counteract the mutational load of recombination. PMID:25646453

  12. Enhanced nonlinear optical characteristics of copper-ion-doped double crossover DNAs

    NASA Astrophysics Data System (ADS)

    Park, Byeongho; Lee, Byung Jic; Dugasani, Sreekantha Reddy; Cho, Youngho; Kim, Chulki; Seo, Minah; Lee, Taikjin; Jhon, Young Min; Choi, Jaebin; Lee, Seok; Park, Sung Ha; Jun, Seong Chan; Yeom, Dong-Il; Rotermund, Fabian; Kim, Jae Hun

    2015-10-01

    The modification of deoxyribonucleic acid (DNA) samples by sequencing the order of bases and doping copper ions opens the possibility for the design of novel nanomaterials exhibiting large optical nonlinearity. We investigated the nonlinear characteristics of copper-ion doped double crossover DNA samples for the first time to the best of our knowledge by using Z-scan and four-wave mixing methods. To accelerate the nonlinear characteristics, we prepared two types of unique DNA nanostructures composed of 148 base pairs doped with copper ions with a facile annealing method. The outstanding third-order nonlinear optical susceptibility of the copper-ion-doped DNA solution, 1.19 × 10-12 esu, was estimated by the conventional Z-scan measurement, whereas the four-wave mixing experiment was also investigated. In the visible spectral range, the copper-ion-doped DNA solution samples provided competent four-wave mixing signals with a remarkable conversion efficiency of -4.15 dB for the converted signal at 627 nm. The interactions between DNA and copper ions contribute to the enhancement of nonlinearity due to structural and functional changes. The present study signifies that the copper-ion-doped double crossover DNA is a potential candidate as a highly efficient novel material for further nonlinear optical applications.

  13. First-principles study of iron spin crossover in the new hexagonal aluminous phase

    NASA Astrophysics Data System (ADS)

    Hsu, Han

    2017-01-01

    The new hexagonal aluminous (NAL) phase, chemical formula A B2C6O12 (A = Na+, K+, Ca2 +; B = Mg2 +, Fe2 +, Fe3 +; C = Al3 +, Si4 +, Fe3 +), is considered a major component (˜20 vol%) of mid-ocean ridge basalt (MORB) under the lower-mantle condition. As MORB can be transported back into the Earth's lower mantle via subduction, a thorough knowledge of the NAL phase is essential to fully understand the fate of subducted MORB and its role in mantle dynamics and heterogeneity. In this Rapid Communication, the complicated spin crossover of the Fe-bearing NAL phase is revealed by a series of local density approximation + self-consistent Hubbard U (LDA+Us c) calculations. Only the ferric iron (Fe3 +) substituting Al/Si in the octahedral (C ) site undergoes a crossover from the high-spin (HS) to the low-spin (LS) state at ˜40 GPa, while iron substituting Mg in the trigonal-prismatic (B ) site remains in the HS state, regardless of its oxidation state (Fe2 + or Fe3 +). The volume/elastic anomalies and the iron nuclear quadrupole splittings determined by calculations are in great agreement with room-temperature experiments. The calculations further predict that the HS-LS transition pressure of the NAL phase barely increases with temperature due to the three nearly degenerate LS states of Fe3 +, suggesting that the elastic anomalies of this mineral can occur at the top lower mantle.

  14. Cooperativity of Spin Crossover Complexes: Combining Periodic Density Functional Calculations and Monte Carlo Simulation.

    PubMed

    Kreutzburg, Lars; Hübner, Christian G; Paulsen, Hauke

    2017-02-13

    The total enthalpies of the 16 different spin configurations that can be realized in the unit cell of the archetype spin crossover complex [Fe(phen)2(NCS)2] (phen = 1,2-phenanthroline) were calculated, applying periodic density functional theory combined with the Hubbard model and the Grimme-D2 dispersion correction (DFT+U+D2). The obtained enthalpy differences between the individual spin configurations were used to determine spin couplings of an Ising-like model, and subsequent Monte Carlo simulations for this model allowed the estimation of the phenomenological interaction parameter Γ of the Slichter-Drickamer model, which is commonly used to describe the cooperativity of the spin transition. The calculation procedure described here-which led to an estimate of about 3 kJ·mol-1 for Γ, in good agreement with experiment-may be used to predict from first principles how modifications of spin crossover complexes can change the character of the spin transition from gradual to abrupt and vice versa.

  15. Dynamic heterogeneity in crossover spin facilitated model of supercooled liquid and fractional Stokes-Einstein relation

    SciTech Connect

    Choi, Seo-Woo; Kim, Soree; Jung, YounJoon

    2015-06-28

    Kinetically constrained models have gained much interest as models that assign the origins of interesting dynamic properties of supercooled liquids to dynamical facilitation mechanisms that have been revealed in many experiments and numerical simulations. In this work, we investigate the dynamic heterogeneity in the fragile-to-strong liquid via Monte Carlo method using the model that linearly interpolates between the strong liquid-like behavior and the fragile liquid-like behavior by an asymmetry parameter b. When the asymmetry parameter is sufficiently small, smooth fragile-to-strong transition is observed both in the relaxation time and the diffusion constant. Using these physical quantities, we investigate fractional Stokes-Einstein relations observed in this model. When b is fixed, the system shows constant power law exponent under the temperature change, and the exponent has the value between that of the Frederickson-Andersen model and the East model. Furthermore, we investigate the dynamic length scale of our systems and also find the crossover relation between the relaxation time. We ascribe the competition between energetically favored symmetric relaxation mechanism and entropically favored asymmetric relaxation mechanism to the fragile-to-strong crossover behavior.

  16. Spin transition in arrays of gold nanoparticles and spin crossover molecules.

    PubMed

    Devid, Edwin J; Martinho, Paulo N; Kamalakar, M Venkata; Šalitroš, Ivan; Prendergast, Úna; Dayen, Jean-François; Meded, Velimir; Lemma, Tibebe; González-Prieto, Rodrigo; Evers, Ferdinand; Keyes, Tia E; Ruben, Mario; Doudin, Bernard; van der Molen, Sense Jan

    2015-04-28

    We investigate if the functionality of spin crossover molecules is preserved when they are assembled into an interfacial device structure. Specifically, we prepare and investigate gold nanoparticle arrays, into which room-temperature spin crossover molecules are introduced, more precisely, [Fe(AcS-BPP)2](ClO4)2, where AcS-BPP = (S)-(4-{[2,6-(dipyrazol-1-yl)pyrid-4-yl]ethynyl}phenyl)ethanethioate (in short, Fe(S-BPP)2). We combine three complementary experiments to characterize the molecule-nanoparticle structure in detail. Temperature-dependent Raman measurements provide direct evidence for a (partial) spin transition in the Fe(S-BPP)2-based arrays. This transition is qualitatively confirmed by magnetization measurements. Finally, charge transport measurements on the Fe(S-BPP)2-gold nanoparticle devices reveal a minimum in device resistance versus temperature, R(T), curves around 260-290 K. This is in contrast to similar networks containing passive molecules only that show monotonically decreasing R(T) characteristics. Backed by density functional theory calculations on single molecular conductance values for both spin states, we propose to relate the resistance minimum in R(T) to a spin transition under the hypothesis that (1) the molecular resistance of the high spin state is larger than that of the low spin state and (2) transport in the array is governed by a percolation model.

  17. An algorithmic analysis of the role of unequal crossover in alpha-satellite DNA evolution.

    PubMed

    Alkan, Can; Bailey, Jeffrey A; Eichler, Evan E; Sahinalp, S Cenk; Tuzun, Eray

    2002-01-01

    Human DNA consists of a large number of tandem repeat sequences. Such sequences are usually called satellites, with the primary example being the centromeric alpha-satellite DNA. The basic repeat unit of the alpha-satellite DNA is a 171 bp monomer. However, with the exception of peripheral alpha-satellite DNA, monomers can be grouped into blocks of k-monomers (4 < k < 20) between which the divergence rate is much smaller (e.g. 5%). Perhaps the simplest and best understood mechanism for tandem repeat array evolution is the unequal crossover. Although it is possible that the alpha-satellite sequence developed as a result of subsequent unequal crossovers only, no formal computational framework seems to have been developed to verify this possibility. In this paper we develop such a framework and perform experiments which seem to indicate that pericentromeric alpha-satellite segments (which are devoid of higher-order structure) are evolutionarily distinct from the higher-order repeat segments. It is likely that the higher order repeats developed independently in distinct regions of the genome and were carried into their current locations through an unknown mechanism of transposition.

  18. The role of unequal crossover in alpha-satellite DNA evolution: a computational analysis.

    PubMed

    Alkan, Can; Eichler, Evan E; Bailey, Jeffrey A; Sahinalp, S Cenk; Tüzün, Eray

    2004-01-01

    Human DNA consists of a large number of tandem repeat sequences. Such sequences are usually called satellites, with the primary example being the centromeric alpha-satellite DNA. The basic repeat unit of the alpha-satellite DNA is a 171 bp monomer. Arbitrary monomer pairs usually have considerable sequence divergence (20-40%). However, with the exception of peripheral alpha-satellite DNA, monomers can be grouped into blocks of k-monomers (4 < or = k < or = 20) between which the divergence rate is much smaller (e.g., 5%). Perhaps the simplest and best understood mechanism for tandem repeat array evolution is unequal crossover. Although it is possible that alpha-satellite sequences developed as a result of subsequent unequal crossovers only, no formal computational framework seems to have been developed to verify this possibility. In this paper, we develop such a framework and report on experiments which imply that pericentromeric alpha-satellite segments (which are devoid of higher order structure) are evolutionarily distinct from the higher order repeat segments. It is likely that the higher order repeats developed independently in distinct regions of the genome and were carried into their current locations through an unknown mechanism of transposition.

  19. Transport in thin insulating films close to the Boson-Fermion Crossover

    NASA Astrophysics Data System (ADS)

    Joy, J. C.; Zhang, X.; Hollen, S. M.; Zhao, C.; Fernandes, G.; Xu, J. M.; Valles, J. M., Jr.

    2015-03-01

    In two-dimensional systems, sufficient levels of disorder are known to localize Cooper Pairs into a phase incoherent insulating state. While many theoretical and experimental works have shown this state's existence, its ubiquity close to the disorder tuned Superconductor to Insulator transition is still an open problem. Recent experiments on nanopatterned Pb0.9Bi0.1 films have suggested a crossover from Bosonic to Fermionic transport deep in the insulating phase, indicating that the Cooper Pair Insulator (CPI) only persists to a finite level of microscopic disorder. The normal state resistance at which this crossover occurs is governed by the extent coupling constant inhomogeneities on the scale of the coherence length, which allow the formation of locally phase coherent superconducting islands in the insulating state. By tuning the scale of these inhomogeneities and examining the extent of the CPI state, we argue that the disorder tuned Superconductor to Insulator transition proceeds via pair breaking and Anderson localization of fermions when the level spacing in the islands approaches the size of the mean field gap. This work was supported by the NSF through grants No. DMR-1307290 and DMR-0907357 and by the AFRL, the ONR, and the AFOSR. Currently at the Center for Emergent Materials, Ohio State University.

  20. Spin-Polarized Fermi Gases in 1D, 3D, and Crossover Regimes

    NASA Astrophysics Data System (ADS)

    Fry, Jacob A.; Revelle, Melissa C.; Olsen, Ben A.; Hulet, Randall G.

    2015-05-01

    We report recent results on mapping the superfluid transition as a function of atomic interaction and global spin polarization in a two-component, 3D gas of fermionic lithium. The atomic interactions are controlled using a Feshbach resonance to tune between the strongly interacting BEC regime and the weakly interacting BCS regime. Previously, a 3D gas was found to have an unpolarized superfluid core that is enclosed by polarized shells. By applying a 2D optical lattice we confine our gas in one-dimensional tubes. In this 1D gas, in contrast to the 3D gas, we found a partially polarized superfluid core and either fully polarized or fully paired wings depending on the overall spin polarization. In the current experiment, we have mapped the phase diagram of the 1D/3D crossover by increasing the inter-tube coupling. The exotic superfluid state, FFLO, is predicted to occupy a large portion of the phase diagram in the crossover regime, making it an ideal location in parameter space for its detection. ARO, NSF, ONR, and The Welch Foundation.

  1. Control of Meiotic Crossovers: From Double-Strand Break Formation to Designation

    PubMed Central

    Gray, Stephen

    2017-01-01

    Meiosis, the mechanism of creating haploid gametes, is a complex cellular process observed across sexually reproducing organisms. Fundamental to meiosis is the process of homologous recombination, whereby DNA double-strand breaks are introduced into the genome and are subsequently repaired to generate either noncrossovers or crossovers. Although homologous recombination is essential for chromosome pairing during prophase I, the resulting crossovers are critical for maintaining homolog interactions and enabling accurate segregation at the first meiotic division. Thus, the placement, timing, and frequency of crossover formation must be exquisitely controlled. In this review, we discuss the proteins involved in crossover formation, the process of their formation and designation, and the rules governing crossovers, all within the context of the important landmarks of prophase I. We draw together crossover designation data across organisms, analyze their evolutionary divergence, and propose a universal model for crossover regulation. PMID:27648641

  2. The spatial regulation of meiotic recombination hotspots: are all DSB hotspots crossover hotspots?

    PubMed

    Serrentino, Maria-Elisabetta; Borde, Valérie

    2012-07-15

    A key step for the success of meiosis is programmed homologous recombination, during which crossovers, or exchange of chromosome arms, take place. Crossovers increase genetic diversity but their main function is to ensure accurate chromosome segregation. Defects in crossover number and position produce aneuploidies that represent the main cause of miscarriages and chromosomal abnormalities such as Down's syndrome. Recombination is initiated by the formation of programmed double strand breaks (DSBs), which occur preferentially at places called DSB hotspots. Among all DSBs generated, only a small fraction is repaired by crossover, the other being repaired by other homologous recombination pathways. Crossover maps have been generated in a number of organisms, defining crossover hotspots. With the availability of genome-wide maps of DSBs as well as the ability to measure genetically the repair outcome at several hotspots, it is becoming more and more clear that not all DSB hotspots behave the same for crossover formation, suggesting that chromosomal features distinguish different types of hotspots.

  3. The case-crossover study design in pharmacoepidemiology.

    PubMed

    Delaney, Joseph A 'Chris'; Suissa, Samy

    2009-02-01

    In the study of the association of transient drug exposures with acute outcomes, the case-crossover design is an efficient alternative to the case-control approach. This design based exclusively on the case series uses within-subject comparisons of drug exposures over time to estimate the rate ratio of the outcome associated with the drug under study. This design inherently removes the biasing effects of unmeasured, time-invariant confounding factors from the estimated rate ratio, but is sensitive to several assumptions. We illustrated the case-crossover design and explored its sensitivity using data from 4028 cases of gastrointestinal bleeding from the General Practice Research Database in assessing the effects of the drug warfarin. We compared the use of different time window lengths to assess exposure and considered the use of a case-time-control design to account for exposure time trends. The case-crossover approach found no excess risk of bleeding with warfarin exposure [rate ratio 0.98; 95% confidence interval (CI): 0.74-1.28] using a 1-month time window. When we restricted the analysis to subjects with truly transient drug exposure, defined by 1 to 3 prescriptions in the previous year, the rate ratio was 2.59 (95% CI: 1.42-4.74). To consider the longer 1-year exposure time window, the case-time-control approach was used and resulted in a rate ratio of 1.72 (95% CI: 1.08-2.43). In conclusion, the case-crossover design is potentially a powerful approach to assess the risk of drugs. This design is, however, highly sensitive to assumptions about intermittency of drug use and the length of the exposure time window, as demonstrated with the example of bleeding associated with warfarin use.

  4. Persistent User Bias in Case-Crossover Studies in Pharmacoepidemiology.

    PubMed

    Hallas, Jesper; Pottegård, Anton; Wang, Shirley; Schneeweiss, Sebastian; Gagne, Joshua J

    2016-10-25

    Studying the effect of chronic medication exposure by means of a case-crossover design may result in an upward-biased odds ratio. In this study, our aim was to assess the occurrence of this bias and to evaluate whether it is remedied by including a control group (the case-time-control design). Using Danish data resources from 1995-2012, we conducted case-crossover and case-time-control analyses for 3 medications (statins, insulin, and thyroxine) in relation to 3 outcomes (retinal detachment, wrist fracture, and ischemic stroke), all with assumed null associations. Controls were matched on age, sex, and index date, and exposure over the preceding 12 months was ascertained. For retinal detachment, the case-crossover odds ratio was 1.60 (95% confidence interval (CI): 1.42, 1.80) for statins, 1.40 (95% CI: 1.02, 1.92) for thyroxine, and 1.53 (95% CI: 1.04, 2.24) for insulin. Estimates for the retinal detachment controls were similar, leading to near-null case-time-control estimates for all 3 medication classes. For wrist fracture and stroke, the odds ratios were higher for cases than for controls, and case-time-control odds ratios were consistently above unity, thus implying significant residual bias. In case-crossover studies of medications, contamination by persistent users confers a moderate bias upward, which is partly remedied by using a control group. The optimal strategy for dealing with this problem is currently unknown.

  5. Hyperon puzzle, hadron-quark crossover and massive neutron stars

    NASA Astrophysics Data System (ADS)

    Masuda, Kota; Hatsuda, Tetsuo; Takatsuka, Tatsuyuki

    2016-03-01

    Bulk properties of cold and hot neutron stars are studied on the basis of the hadron-quark crossover picture where a smooth transition from the hadronic phase to the quark phase takes place at finite baryon density. By using a phenomenological equation of state (EOS) "CRover", which interpolates the two phases at around 3 times the nuclear matter density (ρ0, it is found that the cold NSs with the gravitational mass larger than 2M_{odot} can be sustained. This is in sharp contrast to the case of the first-order hadron-quark transition. The radii of the cold NSs with the CRover EOS are in the narrow range (12.5 ± 0.5) km which is insensitive to the NS masses. Due to the stiffening of the EOS induced by the hadron-quark crossover, the central density of the NSs is at most 4 ρ0 and the hyperon-mixing barely occurs inside the NS core. This constitutes a solution of the long-standing hyperon puzzle. The effect of color superconductivity (CSC) on the NS structures is also examined with the hadron-quark crossover. For the typical strength of the diquark attraction, a slight softening of the EOS due to two-flavor CSC (2SC) takes place and the maximum mass is reduced by about 0.2M_{odot}. The CRover EOS is generalized to the supernova matter at finite temperature to describe the hot NSs at birth. The hadron-quark crossover is found to decrease the central temperature of the hot NSs under isentropic condition. The gravitational energy release and the spin-up rate during the contraction from the hot NS to the cold NS are also estimated.

  6. Dimensional crossover in the torque in a layered superconductor

    NASA Astrophysics Data System (ADS)

    Klemm, R. A.

    1993-04-01

    The procedure of Bulaevski, Ledvij, and Kogan for evaluating the line energy of single, straight vortex in the Lawrence-Doniach model in the linearized phase-only approximation is modified to take accurate account of the vortex core cross-sections. Dimensional crossover effects are found to be pronounced, with oscillations in the regular dependence of the torque for theta approximately = pi/2 and T approximately = T* less than Tc.

  7. Surface and Size Effects in Spin-Crossover Nanocrystals.

    PubMed

    Gudyma, Iurii; Ivashko, Victor; Bobák, Andrej

    2017-12-01

    We perform Monte Carlo simulations to analyze the surface and size effects in spin-crossover nanocrystals using an Ising-like model including surface and core intermolecular interactions. The consequences of downsizing effect on the transition temperature and the width of hysteresis as finger of the system cooperativity are discussed. The critical temperature is calculated using the real-space renormalization method. The obtained results are in agreement with the experimental data.

  8. Surface and Size Effects in Spin-Crossover Nanocrystals

    NASA Astrophysics Data System (ADS)

    Gudyma, Iurii; Ivashko, Victor; Bobák, Andrej

    2017-02-01

    We perform Monte Carlo simulations to analyze the surface and size effects in spin-crossover nanocrystals using an Ising-like model including surface and core intermolecular interactions. The consequences of downsizing effect on the transition temperature and the width of hysteresis as finger of the system cooperativity are discussed. The critical temperature is calculated using the real-space renormalization method. The obtained results are in agreement with the experimental data.

  9. Flow equations for the BCS-BEC crossover

    SciTech Connect

    Diehl, S.; Gies, H.; Pawlowski, J. M.; Wetterich, C.

    2007-08-15

    The functional renormalization group is used for the BCS-BEC crossover in gases of ultracold fermionic atoms. In a simple truncation, we see how universality and an effective theory with composite bosonic diatom states emerge. We obtain a unified picture of the whole phase diagram. The flow reflects different effective physics at different scales. In the BEC limit as well as near the critical temperature, it describes an interacting bosonic theory.

  10. Master crossover functions for one-component fluids.

    PubMed

    Garrabos, Yves; Lecoutre, Carole; Palencia, Fabien; Le Neindre, Bernard; Erkey, Can

    2008-02-01

    By introducing three well-defined dimensionless numbers, we establish the link between the scale dilatation method able to estimate master (i.e., unique) singular behaviors of the one-component fluid subclass and the universal crossover functions recently estimated [Garrabos and Bervillier, Phys. Rev. E 74, 021113 (2006)] from the bounded results of the massive renormalization scheme applied to the Phi(d)(4)(n) model of scalar order parameter (n=1) and three dimensions (d=3), representative of the Ising-like universality class. The master (i.e., rescaled) crossover functions are then able to fit the singular behaviors of any one-component fluid without adjustable parameter, using only one critical energy scale factor, one critical length scale factor, and two dimensionless asymptotic scale factors, which characterize the fluid critical interaction cell at its liquid-gas critical point. An additional adjustable parameter accounts for quantum effects in light fluids at the critical temperature. The effective extension of the thermal field range along the critical isochore where the master crossover functions seems to be valid corresponds to a correlation length greater than three times the effective range of the microscopic short-range molecular interaction.

  11. Case-crossover design and its implementation in R.

    PubMed

    Zhang, Zhongheng

    2016-09-01

    Case-crossover design is a variation of case-control design that it employs persons' history periods as controls. Case-crossover design can be viewed as the hybrid of case-control study and crossover design. Characteristic confounding that is constant within one person can be well controlled with this method. The relative risk and odds ratio, as well as their 95% confidence intervals (CIs), can be estimated using Cochran-Mantel-Haenszel method. R codes for the calculation are provided in the main text. Readers may adapt these codes to their own task. Conditional logistic regression model is another way to estimate odds ratio of the exposure. Furthermore, it allows for incorporation of other time-varying covariates that are not constant within subjects. The model fitting per se is not technically difficult because there is well developed statistical package. However, it is challenging to convert original dataset obtained from case report form to that suitable to be passed to clogit() function. R code for this task is provided and explained in the text.

  12. A Ferroelectric Iron(II) Spin Crossover Material.

    PubMed

    Jornet-Mollá, Verónica; Duan, Yan; Giménez-Saiz, Carlos; Tang, Yuan-Yuan; Li, Peng-Fei; Romero, Francisco M; Xiong, Ren-Gen

    2017-09-07

    A dual-function material in which ferroelectricity and spin crossover coexist in the same temperature range has been obtained. Our synthetic strategy allows the construction of acentric crystal structures in a predictable way and is based on the high directionality of hydrogen bonds. The well-known iron(II) spin crossover complex [Fe(bpp)2 ](2+) (bpp=2,6-bis(pyrazol-3-yl)pyridine), a four-fold noncentrosymmetric H-bond donor, was combined with a disymmetric H-bond acceptor such as the isonicotinate (isonic) anion to afford [Fe(bpp)2 ](isonic)2 ⋅2 H2 O. This low-spin iron(II) compound crystallizes in the acentric nonpolar I4‾ space group and shows piezoelectricity and SHG properties. Upon dehydration, it undergoes a single-crystal to single-crystal structural rearrangement to a monoclinic polar Pc phase that is ferroelectric and exhibits spin crossover. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Crossover of critical Casimir forces between different surface universality classes.

    PubMed

    Mohry, T F; Maciołek, A; Dietrich, S

    2010-06-01

    In confined systems near a continuous phase transition the long-ranged fluctuations of the corresponding order parameter are subject to boundary conditions. These constraints result in so-called critical Casimir forces acting as effective forces on the confining surfaces. For systems belonging to the Ising bulk universality class corresponding to a scalar order parameter the critical Casimir force is studied for the film geometry in the crossover regime characterized by different surface fields at the two surfaces. The scaling function of the critical Casimir force is calculated within mean-field theory. Within our approach, the scaling functions of the critical Casimir force and of the order parameter profile for finite surface fields can be mapped by rescaling, except for a narrow crossover regime, onto the corresponding scaling function of the so-called normal fixed point of strong surface fields. In the crossover regime, the critical Casimir force as function of temperature exhibits more than one extremum and for certain ranges of surface field strengths it changes sign twice upon varying temperature. Monte Carlo simulation data obtained for a three-dimensional Ising film show similar trends. The sign of the critical Casimir force can be inferred from the comparison of the order parameter profiles in the film and in the semi-infinite geometry.

  14. Automatic identification of vessel crossovers in retinal images

    NASA Astrophysics Data System (ADS)

    Sánchez, L.; Barreira, N.; Penedo, M. G.; Cancela, B.

    2015-02-01

    Crossovers and bifurcations are interest points of the retinal vascular tree useful to diagnose diseases. Specifically, detecting these interest points and identifying which of them are crossings will give us the opportunity to search for arteriovenous nicking, this is, an alteration of the vessel tree where an artery is crossed by a vein and the former compresses the later. These formations are a clear indicative of hypertension, among other medical problems. There are several studies that have attempted to define an accurate and reliable method to detect and classify these relevant points. In this article, we propose a new method to identify crossovers. Our approach is based on segmenting the vascular tree and analyzing the surrounding area of each interest point. The minimal path between vessel points in this area is computed in order to identify the connected vessel segments and, as a result, to distinguish between bifurcations and crossovers. Our method was tested using retinographies from public databases DRIVE and VICAVR, obtaining an accuracy of 90%.

  15. Residuals and outliers in replicate design crossover studies.

    PubMed

    Schall, Robert; Endrenyi, Laszlo; Ring, Arne

    2010-07-01

    Outliers in bioequivalence trials may arise through various mechanisms, requiring different interpretation and handling of such data points. For example, regulatory authorities might permit exclusion from analysis of outliers caused by product or process failure, while exclusion of outliers caused by subject-by-treatment interaction generally is not acceptable. In standard 2 x 2 crossover studies it is not possible to distinguish between relevant types of outliers based on statistical criteria alone. However, in replicate design (2-treatment, 4-period) crossover studies three types of outliers can be distinguished: (i) Subject outliers are usually unproblematic, at least regarding the analysis of bioequivalence, and may require no further action; (ii) Subject-by-formulation outliers may affect the outcome of the bioequivalence test but generally cannot simply be removed from analysis; and (iii) Removal of single-data-point outliers from analysis may be justified in certain cases. As a very simple but effective diagnostic tool for the identification and classification of outliers in replicate design crossover studies we propose to calculate and plot three types of residual corresponding to the three different types of outliers that can be distinguished. The residuals are obtained from four mutually orthogonal linear contrasts of the four data points associated with each subject. If preferred, outlier tests can be applied to the resulting sets of residuals after suitable standardization.

  16. Crossover among structural motifs in Pd-Au nanoalloys.

    PubMed

    Zhu, Beien; Guesmi, Hazar; Creuze, Jérôme; Legrand, Bernard; Mottet, Christine

    2015-11-14

    The crossovers among the most abundant structural motifs (icosahedra, decahedra and truncated octahedra) of Pd-Au nanoalloys have been determined theoretically in a size range between 2 and 7 nm and for three compositions equivalent to Pd3Au, PdAu and PdAu3. The chemical ordering and segregation optimisation are performed via Monte Carlo simulations using semi-empirical tight-binding potentials fitted to ab initio calculations. The chemical configurations are then quenched via molecular dynamic simulations in order to compare their energy and characterize the equilibrium structures as a function of the cluster size. For the smaller sizes (of around 300 atoms and fewer) the structures are also optimized at the electronic level within ab initio calculations in order to validate the semi-empirical potential. The predictions of the crossover sizes for the nanoalloys cannot be simply extrapolated from the crossover of the pure nanoparticles but imply stress release phenomena related to the size misfit between the two metals. Indeed, alloying extends the range of stability of the icosahedron beyond that of the pure systems and the energy differences between decahedra and truncated octahedra become asymptotic, around the sizes of 5-6 nm. Nevertheless, such equilibrium results should be modulated regarding kinetic considerations or possible gas adsorption under experimental conditions.

  17. Spin crossover in ferropericlase and some consequences for mantle velocities

    NASA Astrophysics Data System (ADS)

    Wentzcovitch, R. M.

    2015-12-01

    The spin crossover in ferropericlase ((Mg,Fe)O) introduces anomalies in its thermodynamics and thermoelastic properties [1] with impactful consequences on lower mantle velocities. These anomalies fundamentally change the interpretation of the origin of lateral heterogeneities in the mid lower mantle. In particular, SCF reduces the sensitivity of longitudinal velocity (VP) to lateral temperature variations around 1700 km [2]. It also dramatically impacts the manifestation of two important types of compositional heterogeneities, i.e., change in iron concentration in Fp or in molar fraction of Fp in the aggregate. It enhances the sensitivity of Vϕ and VP to these compositional variations by several-fold. In addition, it affects the mantle adiabatic geotherm, altering the radial velocity profile. Here I will review these effects and relate them to some potential features observed in seismic tomography models. [1] Wu, Z.Q., Justo, J. F., & Wentzcovitch, R.M. (2013). Elastic anomalies in a spin-crossover system: ferropericlase at lower mantle conditions, Phys. Rev. Lett. 110, 228501 (2013). [2] Wu, Z.Q., & Wentzcovitch, R.M. (2014). Spin crossover in ferropericlase and velocity heterogeneities in the lower mantle. Proc. Natl. Acad. Sci. U. S. A. 111: 10468-10472.

  18. Pressure and Temperature Spin Crossover Sensors with Optical Detection

    PubMed Central

    Linares, Jorge; Codjovi, Epiphane; Garcia, Yann

    2012-01-01

    Iron(II) spin crossover molecular materials are made of coordination centres switchable between two states by temperature, pressure or a visible light irradiation. The relevant macroscopic parameter which monitors the magnetic state of a given solid is the high-spin (HS) fraction denoted nHS, i.e., the relative population of HS molecules. Each spin crossover material is distinguished by a transition temperature T1/2 where 50% of active molecules have switched to the low-spin (LS) state. In strongly interacting systems, the thermal spin switching occurs abruptly at T1/2. Applying pressure induces a shift from HS to LS states, which is the direct consequence of the lower volume for the LS molecule. Each material has thus a well defined pressure value P1/2. In both cases the spin state change is easily detectable by optical means thanks to a thermo/piezochromic effect that is often encountered in these materials. In this contribution, we discuss potential use of spin crossover molecular materials as temperature and pressure sensors with optical detection. The ones presenting smooth transitions behaviour, which have not been seriously considered for any application, are spotlighted as potential sensors which should stimulate a large interest on this well investigated class of materials. PMID:22666041

  19. Viscous fingering near the percolation threshold: Double-crossover phenomena

    NASA Astrophysics Data System (ADS)

    Nagatani, Takashi; Stanley, H. Eugene

    1991-03-01

    Viscous fingering at a nonzero viscosity ratio on percolating clusters is considered to study morphological changes of patterns formed by the injected fluid in porous media. A fraction P of bonds is filled by the displaced fluid, while the others (1-P) are blocked, where P is the usual percolation probability. Fluid with a low viscosity is injected into the percolating cluster filled by the displaced fluid with high viscosity. Morphological changes of patterns of the injected fluid are described in terms of crossover phenomena by making use of a four-parameter position-space renormalization-group method. It is found that when μI/μD<<(P-Pc)<<1 the double crossover occurs from the diffusion-limited aggregation (DLA) on an incipient percolation cluster through the DLA on the perfect lattice to the dense structure, and when 1>>μI/μD>>(P-Pc) the other double crossover appears from the DLA on an incipient percolation cluster through the invasion percolation to the dense structure, where μI/μD is the viscosity ratio and Pc the critical percolation probability.

  20. Fine Scale Analysis of Crossover and Non-Crossover and Detection of Recombination Sequence Motifs in the Honeybee (Apis mellifera)

    PubMed Central

    Bessoltane, Nadia; Toffano-Nioche, Claire; Solignac, Michel; Mougel, Florence

    2012-01-01

    Background Meiotic exchanges are non-uniformly distributed across the genome of most studied organisms. This uneven distribution suggests that recombination is initiated by specific signals and/or regulations. Some of these signals were recently identified in humans and mice. However, it is unclear whether or not sequence signals are also involved in chromosomal recombination of insects. Methodology We analyzed recombination frequencies in the honeybee, in which genome sequencing provided a large amount of SNPs spread over the entire set of chromosomes. As the genome sequences were obtained from a pool of haploid males, which were the progeny of a single queen, an oocyte method (study of recombination on haploid males that develop from unfertilized eggs and hence are the direct reflect of female gametes haplotypes) was developed to detect recombined pairs of SNP sites. Sequences were further compared between recombinant and non-recombinant fragments to detect recombination-specific motifs. Conclusions Recombination events between adjacent SNP sites were detected at an average distance of 92 bp and revealed the existence of high rates of recombination events. This study also shows the presence of conversion without crossover (i. e. non-crossover) events, the number of which largely outnumbers that of crossover events. Furthermore the comparison of sequences that have undergone recombination with sequences that have not, led to the discovery of sequence motifs (CGCA, GCCGC, CCGCA), which may correspond to recombination signals. PMID:22567142

  1. Fine-Scale Crossover Rate Variation on the Caenorhabditis elegans X Chromosome

    PubMed Central

    Bernstein, Max R.; Rockman, Matthew V.

    2016-01-01

    Meiotic recombination creates genotypic diversity within species. Recombination rates vary substantially across taxa, and the distribution of crossovers can differ significantly among populations and between sexes. Crossover locations within species have been found to vary by chromosome and by position within chromosomes, where most crossover events occur in small regions known as recombination hotspots. However, several species appear to lack hotspots despite significant crossover heterogeneity. The nematode Caenorhabditis elegans was previously found to have the least fine-scale variation in crossover distribution among organisms studied to date. It is unclear whether this pattern extends to the X chromosome given its unique compaction through the pachytene stage of meiotic prophase in hermaphrodites. We generated 798 recombinant nested near-isogenic lines (NILs) with crossovers in a 1.41 Mb region on the left arm of the X chromosome to determine if its recombination landscape is similar to that of the autosomes. We find that the fine-scale variation in crossover rate is lower than that of other model species, and is inconsistent with hotspots. The relationship of genomic features to crossover rate is dependent on scale, with GC content, histone modifications, and nucleosome occupancy being negatively associated with crossovers. We also find that the abundances of 4- to 6-bp DNA motifs significantly explain crossover density. These results are consistent with recombination occurring at unevenly distributed sites of open chromatin. PMID:27172189

  2. Mechanistic studies of photoinduced spin crossover and electron transfer in inorganic complexes.

    PubMed

    Zhang, Wenkai; Gaffney, Kelly J

    2015-04-21

    Electronic excited-state phenomena provide a compelling intersection of fundamental and applied research interests in the chemical sciences. This holds true for coordination chemistry, where harnessing the strong optical absorption and photocatalytic activity of compounds depends on our ability to control fundamental physical and chemical phenomena associated with the nonadiabatic dynamics of electronic excited states. The central events of excited-state chemistry can critically influence the dynamics of electronic excited states, including internal conversion (transitions between distinct electronic states) and intersystem crossing (transitions between electronic states with different spin multiplicities), events governed by nonadiabatic interactions between electronic states in close proximity to conical intersections, as well as solvation and electron transfer. The diversity of electronic and nuclear dynamics also makes the robust interpretation of experimental measurements challenging. Developments in theory, simulation, and experiment can all help address the interpretation and understanding of chemical dynamics in organometallic and coordination chemistry. Synthesis presents the opportunity to chemically engineer the strength and symmetry of the metal-ligand interactions. This chemical control can be exploited to understand the influence of electronic ground state properties on electronic excited-state dynamics. New time-resolved experimental methods and the insightful exploitation of established methods have an important role in understanding, and ideally controlling, the photophysics and photochemistry of transition metal complexes. Techniques that can disentangle the coupled motion of electrons and nuclear dynamics warrant emphasis. We present a review of electron localization dynamics in charge transfer excited states and the dynamics of photoinitiated spin crossover dynamics. Both electron localization and spin crossover have been investigated by

  3. Finite-size effects on the lattice dynamics in spin crossover nanomaterials. II. Molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Mikolasek, Mirko; Nicolazzi, William; Terki, Férial; Molnár, Gábor; Bousseksou, Azzedine

    2017-07-01

    In the first part of this work, an experimental study of the lattice dynamics of spin crossover nanoparticles was performed using the nuclear inelastic scattering (NIS). A size dependence of low energy phonon modes appears under 10 nm, but its origin is not well understood. In this paper, we investigate the phonon confinement effects in the framework of molecular dynamics simulations by modeling three-dimensional nanoparticles considering a cubic lattice with an octahedral pattern. The vibrational density of states is computed and compared to the experiment. The simulations allow one to highlight both the role of the phonon quantification and the role of the size and shape distributions of particles on the extracted parameters leading to a better understanding of the experimental results.

  4. Crossover from negative to positive shear rate dependence in granular friction

    NASA Astrophysics Data System (ADS)

    Kuwano, Osamu; Ando, Ryosuke; Hatano, Takahiro

    2013-04-01

    Abstract The frictional properties of granular matter are important for analyzing various phenomena in geosciences. Here, we conduct an <span class="hlt">experiment</span> on the shear-rate dependence of the friction coefficient, which determines the stability of granular flow. By changing the shear rate over four orders of magnitude, we find the characteristic rate at which the least friction is realized associated with the <span class="hlt">crossover</span> from negative to positive shear rate dependence. The least friction is explained in terms of the competition between two very different physical processes, namely frictional healing and anelasticity. We determine the expression of the characteristic shear rate, which is proportional to the square root of the normal stress.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhRvA..73f5601D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhRvA..73f5601D"><span>Expansion of a Fermi cloud in the BCS-BEC <span class="hlt">crossover</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Diana, G.; Manini, N.; Salasnich, L.</p> <p>2006-06-01</p> <p>We study the free expansion of a dilute two-component Fermi gas with attractive interspecies interaction in the Bardeen-Cooper-Schrieffer-Bose-Einstein condensate (BCS-BEC) <span class="hlt">crossover</span>. We apply a time-dependent parameter-free density-functional theory by using two choices of the equation of state: an analytic formula based on Monte Carlo data and the mean-field equation of state resulting from the extended BCS equations. The calculated axial and transverse radii and the aspect ratio of the expanding cloud are compared to experimental data on vapors of Li6 atoms. Remarkably, the mean-field theory shows a better agreement with the <span class="hlt">experiments</span> than the theory based on the Monte Carlo equation of state. Both theories predict a measurable dependence of the aspect ratio on expansion time and on scattering length.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMMR54A..01H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMMR54A..01H"><span>Spin <span class="hlt">crossover</span> and iron-rich dense partial melt in pyrolitic lower mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hirose, K.; Tateno, S.</p> <p>2012-12-01</p> <p>Spin <span class="hlt">crossover</span> of iron may occur not only in solids but also in melts in the lower mantle. The resulting change in Fe partitioning strongly affects the buoyancy of partial melts near the base of the mantle. Nomura et al. [2011 Nature] measured the Fe partitioning in (Mg0.89Fe0.11)2 SiO4 bulk composition over the entire mantle pressure range, demonstrating that Fe-Mg distribution coefficient KD = ([FePv]/[MgPv]) / ([Femelt]/[Mgmelt]) between (Mg,Fe)SiO3 perovskite and melt dropped from ~0.25 to <0.1 around 76 GPa, resulting in strong Fe-enrichment in melts and thereby dense partial melts in the mid-lower mantle. In contrast, the most recent <span class="hlt">experiments</span> by Andrault et al. [2012 Nature] found much higher KD and less Fe-enrichment in partial melts formed in primitive mantle composition, suggesting that melt is not dense in the lowermost mantle. Here we extend our measurements in pyrolitic natural mantle (KLB-1 peridotite) bulk composition. The distribution coefficient KD (total Fe/Mg) was determined at 40-180 GPa by a combination of laser-heated diamond-anvil cell <span class="hlt">experiments</span> and chemical analyses of recovered samples using field-emission-type electron microprobe (FE-EPMA). Our results demonstrate that KD between perovskite and melt is about 0.3 up to 58 GPa, consistent with earlier multi-anvil data. It then dropped to ~0.1 above 68 GPa, indicating strong Fe-enrichment in partial melts. These results are in excellent agreement with those of Nomura et al. [2011], indicating that Fe-rich partial melts are more dense than solids below 1600-km depth in the lower mantle. The observed Fe-enrichment in partial melt above 68 GPa can be explained by a spin <span class="hlt">crossover</span> of iron in silicate melt, as discussed previously in Nomura et al. [2011].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25133988','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25133988"><span>Single water entropy: hydrophobic <span class="hlt">crossover</span> and application to drug binding.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sasikala, Wilbee D; Mukherjee, Arnab</p> <p>2014-09-11</p> <p>Entropy of water plays an important role in both chemical and biological processes e.g. hydrophobic effect, molecular recognition etc. Here we use a new approach to calculate translational and rotational entropy of the individual water molecules around different hydrophobic and charged solutes. We show that for small hydrophobic solutes, the translational and rotational entropies of each water molecule increase as a function of its distance from the solute reaching finally to a constant bulk value. As the size of the solute increases (0.746 nm), the behavior of the translational entropy is opposite; water molecules closest to the solute have higher entropy that reduces with distance from the solute. This indicates that there is a <span class="hlt">crossover</span> in translational entropy of water molecules around hydrophobic solutes from negative to positive values as the size of the solute is increased. Rotational entropy of water molecules around hydrophobic solutes for all sizes increases with distance from the solute, indicating the absence of <span class="hlt">crossover</span> in rotational entropy. This makes the <span class="hlt">crossover</span> in total entropy (translation + rotation) of water molecule happen at much larger size (>1.5 nm) for hydrophobic solutes. Translational entropy of single water molecule scales logarithmically (Str(QH) = C + kB ln V), with the volume V obtained from the ellipsoid of inertia. We further discuss the origin of higher entropy of water around water and show the possibility of recovering the entropy loss of some hypothetical solutes. The results obtained are helpful to understand water entropy behavior around various hydrophobic and charged environments within biomolecules. Finally, we show how our approach can be used to calculate the entropy of the individual water molecules in a protein cavity that may be replaced during ligand binding.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12902160','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12902160"><span>Control of <span class="hlt">cross-over</span> by single-strand DNA resection.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Prado, Félix; Aguilera, Andrés</p> <p>2003-08-01</p> <p>Control of DNA <span class="hlt">cross-overs</span> is necessary for meiotic recombination and genome integrity. The frequency of <span class="hlt">cross-overs</span> is dependent on homology length and the conversion tract, but the mechanisms underlying the regulation of <span class="hlt">cross-overs</span> remain unknown. We propose that 5'-end resection, a key intermediate in double-strand break repair, could determine the formation of <span class="hlt">cross-overs</span>. Extensive DNA resection might favor gene conversion without <span class="hlt">cross-over</span> by channeling recombination events through synthesis-dependent strand-annealing. In reactions with short regions of homology, resection beyond the homologous sequence would impede Holliday junction formation and, consequently, <span class="hlt">cross-over</span>. Extensive DNA resection could be an effective mechanism to prevent reciprocal exchanges between dispersed DNA sequences, and thus contribute to the genome stability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15506859','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15506859"><span><span class="hlt">Crossover</span> of marital dissatisfaction during military downsizing among Russian army officers and their spouses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Westman, Mina; Vinokur, Amiram D; Hamilton, V Lee; Roziner, Ilan</p> <p>2004-10-01</p> <p>This study examined mechanisms of strain <span class="hlt">crossover</span> within couples and the moderating role of gender. Data were collected at a time of military downsizing from a sample of 1,250 Russian army officers and their spouses. The authors tested a model that incorporated 3 mechanisms for the <span class="hlt">crossover</span> of marital dissatisfaction among dual-earner couples. The model provided support for 2 suggested <span class="hlt">crossover</span> mechanisms: direct reactions of <span class="hlt">crossover</span> and indirect mediated effects through social undermining. Strong evidence was also provided for gender asymmetry in the <span class="hlt">crossover</span> process. Marital dissatisfaction crossed over from husbands to wives but not vice versa, and social undermining behavior played a role in the process of <span class="hlt">crossover</span> of marital dissatisfaction for husbands but not for wives.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1032567','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1032567"><span>Meige syndrome: double-blind <span class="hlt">crossover</span> study of sodium valproate.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Snoek, J W; van Weerden, T W; Teelken, A W; van den Burg, W; Lakke, J P</p> <p>1987-01-01</p> <p>A double-blind <span class="hlt">crossover</span> study of sodium valproate and placebo was conducted in five patients with Meige syndrome. CSF neurotransmitter studies were performed at the end of each treatment period. GABA levels were not influenced by the administration of sodium valproate. An increase in HVA levels was observed in every patient, which may reflect an increase in central dopaminergic activity. This finding may explain the trend towards clinical deterioration which was observed during treatment with sodium valproate. Sodium valproate appears to be ineffective in Meige syndrome. PMID:3121795</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22252826','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22252826"><span>Computational approach to the study of thermal spin <span class="hlt">crossover</span> phenomena</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rudavskyi, Andrii; Broer, Ria; Sousa, Carmen</p> <p>2014-05-14</p> <p>The key parameters associated to the thermally induced spin <span class="hlt">crossover</span> process have been calculated for a series of Fe(II) complexes with mono-, bi-, and tridentate ligands. Combination of density functional theory calculations for the geometries and for normal vibrational modes, and highly correlated wave function methods for the energies, allows us to accurately compute the entropy variation associated to the spin transition and the zero-point corrected energy difference between the low- and high-spin states. From these values, the transition temperature, T{sub 1/2}, is estimated for different compounds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24501227','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24501227"><span>Analysis of <span class="hlt">cross-over</span> studies with missing data.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rosenkranz, Gerd K</p> <p>2015-08-01</p> <p>This paper addresses some aspects of the analysis of <span class="hlt">cross-over</span> trials with missing or incomplete data. A literature review on the topic reveals that many proposals provide correct results under the missing completely at random assumption while only some consider the more general missing at random situation. It is argued that mixed-effects models have a role in this context to recover some of the missing intra-subject from the inter-subject information, in particular when missingness is ignorable. Eventually, sensitivity analyses to deal with more general missingness mechanisms are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21024343','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21024343"><span>Superfluid Equation of State of Dilute Composite Bosons</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Leyronas, X.; Combescot, R.</p> <p>2007-10-26</p> <p>We present an exact theory of the <span class="hlt">BEC-BCS</span> <span class="hlt">crossover</span> in the Bose-Einstein-condensate (BEC) regime, which treats explicitly dimers as made of two fermions. We apply our framework, at zero temperature, to the calculation of the equation of state. We find that, when expanding the chemical potential in powers of the density n up to the Lee-Huang-Yang order, proportional to n{sup 3/2}, the result is identical to the one of elementary bosons in terms of the dimer-dimer scattering length a{sub M}, the composite nature of the dimers appearing only in the next order term proportional to n{sup 2}.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvA..96b3619S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvA..96b3619S"><span>Effective-range dependence of two-dimensional Fermi gases</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schonenberg, L. M.; Verpoort, P. C.; Conduit, G. J.</p> <p>2017-08-01</p> <p>The Feshbach resonance provides precise control over the scattering length and effective range of interactions between ultracold atoms. We propose the ultratransferable pseudopotential to model effective interaction ranges -1.5 ≤kF2Reff2≤0 , where Reff is the effective range and kF is the Fermi wave vector, describing narrow to broad Feshbach resonances. We develop a mean-field treatment and exploit the pseudopotential to perform a variational and diffusion Monte Carlo study of the ground state of the two-dimensional Fermi gas, reporting on the ground-state energy, contact, condensate fraction, momentum distribution, and pair-correlation functions as a function of the effective interaction range across the <span class="hlt">BEC-BCS</span> <span class="hlt">crossover</span>. The limit kF2Reff2→-∞ is a gas of bosons with zero binding energy, whereas ln(kFa )→-∞ corresponds to noninteracting bosons with infinite binding energy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvL.118j3403L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvL.118j3403L"><span>Connecting Few-Body Inelastic Decay to Quantum Correlations in a Many-Body System: A Weakly Coupled Impurity in a Resonant Fermi Gas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laurent, Sébastien; Pierce, Matthieu; Delehaye, Marion; Yefsah, Tarik; Chevy, Frédéric; Salomon, Christophe</p> <p>2017-03-01</p> <p>We study three-body recombination in an ultracold Bose-Fermi mixture. We first show theoretically that, for weak interspecies coupling, the loss rate is proportional to Tan's contact. Second, using a <mml:mmultiscripts>Li 7 </mml:mmultiscripts> /<mml:mmultiscripts>Li 6 </mml:mmultiscripts> mixture we probe the recombination rate in both the thermal and dual superfluid regimes. We find excellent agreement with our model in the <span class="hlt">BEC-BCS</span> <span class="hlt">crossover</span>. At unitarity where the fermion-fermion scattering length diverges, we show that the loss rate is proportional to nf4 /3 , where nf is the fermionic density. This unusual exponent signals nontrivial two-body correlations in the system. Our results demonstrate that few-body losses can be used as a quantitative probe of quantum correlations in many-body ensembles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhRvA..82f1605Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhRvA..82f1605Z"><span>Quantitative comparison between theoretical predictions and experimental results for Bragg spectroscopy of a strongly interacting Fermi superfluid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zou, Peng; Kuhnle, Eva D.; Vale, Chris J.; Hu, Hui</p> <p>2010-12-01</p> <p>Theoretical predictions for the dynamic structure factor of a harmonically trapped Fermi superfluid near the Bose-Einstein condensate-Bardeen-Cooper-Schrieffer (<span class="hlt">BEC-BCS</span>) <span class="hlt">crossover</span> are compared with recent Bragg spectroscopy measurements at large transferred momenta. The calculations are based on a random-phase (or time-dependent Hartree-Fock-Gorkov) approximation generalized to the strongly interacting regime. Excellent agreement with experimental spectra at low temperatures is obtained, with no free parameters. Theoretical predictions for zero-temperature static structure factor are also found to agree well with the experimental results and independent theoretical calculations based on the exact Tan relations. The temperature dependence of the structure factors at unitarity is predicted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28339272','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28339272"><span>Connecting Few-Body Inelastic Decay to Quantum Correlations in a Many-Body System: A Weakly Coupled Impurity in a Resonant Fermi Gas.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Laurent, Sébastien; Pierce, Matthieu; Delehaye, Marion; Yefsah, Tarik; Chevy, Frédéric; Salomon, Christophe</p> <p>2017-03-10</p> <p>We study three-body recombination in an ultracold Bose-Fermi mixture. We first show theoretically that, for weak interspecies coupling, the loss rate is proportional to Tan's contact. Second, using a ^{7}Li/^{6}Li mixture we probe the recombination rate in both the thermal and dual superfluid regimes. We find excellent agreement with our model in the <span class="hlt">BEC-BCS</span> <span class="hlt">crossover</span>. At unitarity where the fermion-fermion scattering length diverges, we show that the loss rate is proportional to n_{f}^{4/3}, where n_{f} is the fermionic density. This unusual exponent signals nontrivial two-body correlations in the system. Our results demonstrate that few-body losses can be used as a quantitative probe of quantum correlations in many-body ensembles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22113599','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22113599"><span>Quantum field theory for condensation of bosons and fermions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>De Souza, Adriano N.; Filho, Victo S.</p> <p>2013-03-25</p> <p>In this brief review, we describe the formalism of the quantum field theory for the analysis of the condensation phenomenon in bosonic systems, by considering the cases widely verified in laboratory of trapped gases as condensate states, either with attractive or with repulsive two-body interactions. We review the mathematical formulation of the quantum field theory for many particles in the mean-field approximation, by adopting contact interaction potential. We also describe the phenomenon of condensation in the case of fermions or the degenerate Fermi gas, also verified in laboratory in the <span class="hlt">crossover</span> <span class="hlt">BEC-BCS</span> limit. We explain that such a phenomenon, equivalent to the bosonic condensation, can only occur if we consider the coupling of particles in pairs behaving like bosons, as occurs in the case of Cooper's pairs in superconductivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JPCM...24f0301C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JPCM...24f0301C"><span>PREFACE: Dynamic <span class="hlt">crossover</span> phenomena in water and other glass-forming liquids Dynamic <span class="hlt">crossover</span> phenomena in water and other glass-forming liquids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Sow-Hsin; Baglioni, Piero</p> <p>2012-02-01</p> <p> dynamics of the water molecules in the solution is observed in the single-particle relaxational dynamics in the μeV (nanosecond) time scale, but not in the collective dynamics on the meV (picosecond) time scale. Mallamace et al discuss the dynamic <span class="hlt">crossover</span> phenomenon in both bulk water and protein hydration water. They collect previous and new experimental data from different experimental techniques and molecular dynamic simulations, and are able to develop a unified picture for the different dynamical findings. Gallo et al present a MD study of confined water in MCM-41S-15 in order to test the applicability of Mode Coupling Theory (MCT) to the dynamics of the hydration water confined in the cylindrical pores of nominal diameter 15 Å. They find that the self dynamics of the hydration water is well described by MCT down to the <span class="hlt">crossover</span> temperature TC. However, below TC the predictions of idealized MCT no longer apply, since hopping processes intervene and water turns into a strong liquid. Soper raises some questions as to the validity of the analysis method employed to determine the density of water confined in porous silica material MCM-41-S15 from recent neutron scattering <span class="hlt">experiments</span>. Professors Stanley, Franzese and his collaborators describe an efficient Monte Carlo simulation of a coarse-grained model of water to study the phase diagram of a water monolayer confined in a fixed disordered matrix of hydrophobic nanoparticles between two hydrophobic plates. They find a drastic change of phase behavior of the confined water, such as shortening of the liquid-liquid phase transition line, upon increasing the concentration of the hydrophobic nano-particles. Sciortino and collaborators compute the equilibrium phase diagram of two simple models for patchy particles with three and five patches in a very broad range of pressure and temperature. The three-patch model produces a stable gas-liquid critical point. Yun Liu et al investigate, via small angle neutron scattering and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4878770','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4878770"><span>High-Resolution Mapping of <span class="hlt">Crossover</span> and Non-<span class="hlt">crossover</span> Recombination Events by Whole-Genome Re-sequencing of an Avian Pedigree</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Qvarnström, Anna; Ellegren, Hans</p> <p>2016-01-01</p> <p>Recombination is an engine of genetic diversity and therefore constitutes a key process in evolutionary biology and genetics. While the outcome of <span class="hlt">crossover</span> recombination can readily be detected as shuffled alleles by following the inheritance of markers in pedigreed families, the more precise location of both <span class="hlt">crossover</span> and non-<span class="hlt">crossover</span> recombination events has been difficult to pinpoint. As a consequence, we lack a detailed portrait of the recombination landscape for most organisms and knowledge on how this landscape impacts on sequence evolution at a local scale. To localize recombination events with high resolution in an avian system, we performed whole-genome re-sequencing at high coverage of a complete three-generation collared flycatcher pedigree. We identified 325 <span class="hlt">crossovers</span> at a median resolution of 1.4 kb, with 86% of the events localized to <10 kb intervals. Observed <span class="hlt">crossover</span> rates were in excellent agreement with data from linkage mapping, were 52% higher in male (3.56 cM/Mb) than in female meiosis (2.28 cM/Mb), and increased towards chromosome ends in male but not female meiosis. <span class="hlt">Crossover</span> events were non-randomly distributed in the genome with several distinct hot-spots and a concentration to genic regions, with the highest density in promoters and CpG islands. We further identified 267 non-<span class="hlt">crossovers</span>, whose location was significantly associated with <span class="hlt">crossover</span> locations. We detected a significant transmission bias (0.18) in favour of ‘strong’ (G, C) over ‘weak’ (A, T) alleles at non-<span class="hlt">crossover</span> events, providing direct evidence for the process of GC-biased gene conversion in an avian system. The approach taken in this study should be applicable to any species and would thereby help to provide a more comprehensive portray of the recombination landscape across organism groups. PMID:27219623</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27219623','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27219623"><span>High-Resolution Mapping of <span class="hlt">Crossover</span> and Non-<span class="hlt">crossover</span> Recombination Events by Whole-Genome Re-sequencing of an Avian Pedigree.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Smeds, Linnéa; Mugal, Carina F; Qvarnström, Anna; Ellegren, Hans</p> <p>2016-05-01</p> <p>Recombination is an engine of genetic diversity and therefore constitutes a key process in evolutionary biology and genetics. While the outcome of <span class="hlt">crossover</span> recombination can readily be detected as shuffled alleles by following the inheritance of markers in pedigreed families, the more precise location of both <span class="hlt">crossover</span> and non-<span class="hlt">crossover</span> recombination events has been difficult to pinpoint. As a consequence, we lack a detailed portrait of the recombination landscape for most organisms and knowledge on how this landscape impacts on sequence evolution at a local scale. To localize recombination events with high resolution in an avian system, we performed whole-genome re-sequencing at high coverage of a complete three-generation collared flycatcher pedigree. We identified 325 <span class="hlt">crossovers</span> at a median resolution of 1.4 kb, with 86% of the events localized to <10 kb intervals. Observed <span class="hlt">crossover</span> rates were in excellent agreement with data from linkage mapping, were 52% higher in male (3.56 cM/Mb) than in female meiosis (2.28 cM/Mb), and increased towards chromosome ends in male but not female meiosis. <span class="hlt">Crossover</span> events were non-randomly distributed in the genome with several distinct hot-spots and a concentration to genic regions, with the highest density in promoters and CpG islands. We further identified 267 non-<span class="hlt">crossovers</span>, whose location was significantly associated with <span class="hlt">crossover</span> locations. We detected a significant transmission bias (0.18) in favour of 'strong' (G, C) over 'weak' (A, T) alleles at non-<span class="hlt">crossover</span> events, providing direct evidence for the process of GC-biased gene conversion in an avian system. The approach taken in this study should be applicable to any species and would thereby help to provide a more comprehensive portray of the recombination landscape across organism groups.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26494791','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26494791"><span>DNA methylation epigenetically silences <span class="hlt">crossover</span> hot spots and controls chromosomal domains of meiotic recombination in Arabidopsis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yelina, Nataliya E; Lambing, Christophe; Hardcastle, Thomas J; Zhao, Xiaohui; Santos, Bruno; Henderson, Ian R</p> <p>2015-10-15</p> <p>During meiosis, homologous chromosomes undergo <span class="hlt">crossover</span> recombination, which is typically concentrated in narrow hot spots that are controlled by genetic and epigenetic information. Arabidopsis chromosomes are highly DNA methylated in the repetitive centromeres, which are also <span class="hlt">crossover</span>-suppressed. Here we demonstrate that RNA-directed DNA methylation is sufficient to locally silence Arabidopsis euchromatic <span class="hlt">crossover</span> hot spots and is associated with increased nucleosome density and H3K9me2. However, loss of CG DNA methylation maintenance in met1 triggers epigenetic <span class="hlt">crossover</span> remodeling at the chromosome scale, with pericentromeric decreases and euchromatic increases in recombination. We used recombination mutants that alter interfering and noninterfering <span class="hlt">crossover</span> repair pathways (fancm and zip4) to demonstrate that remodeling primarily involves redistribution of interfering <span class="hlt">crossovers</span>. Using whole-genome bisulfite sequencing, we show that <span class="hlt">crossover</span> remodeling is driven by loss of CG methylation within the centromeric regions. Using cytogenetics, we profiled meiotic DNA double-strand break (DSB) foci in met1 and found them unchanged relative to wild type. We propose that met1 chromosome structure is altered, causing centromere-proximal DSBs to be inhibited from maturation into interfering <span class="hlt">crossovers</span>. These data demonstrate that DNA methylation is sufficient to silence <span class="hlt">crossover</span> hot spots and plays a key role in establishing domains of meiotic recombination along chromosomes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4407271','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4407271"><span>Juxtaposition of heterozygous and homozygous regions causes reciprocal <span class="hlt">crossover</span> remodelling via interference during Arabidopsis meiosis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ziolkowski, Piotr A; Berchowitz, Luke E; Lambing, Christophe; Yelina, Nataliya E; Zhao, Xiaohui; Kelly, Krystyna A; Choi, Kyuha; Ziolkowska, Liliana; June, Viviana; Sanchez-Moran, Eugenio; Franklin, Chris; Copenhaver, Gregory P; Henderson, Ian R</p> <p>2015-01-01</p> <p>During meiosis homologous chromosomes undergo <span class="hlt">crossover</span> recombination. Sequence differences between homologs can locally inhibit <span class="hlt">crossovers</span>. Despite this, nucleotide diversity and population-scaled recombination are positively correlated in eukaryote genomes. To investigate interactions between heterozygosity and recombination we crossed Arabidopsis lines carrying fluorescent <span class="hlt">crossover</span> reporters to 32 diverse accessions and observed hybrids with significantly higher and lower <span class="hlt">crossovers</span> than homozygotes. Using recombinant populations derived from these crosses we observed that heterozygous regions increase <span class="hlt">crossovers</span> when juxtaposed with homozygous regions, which reciprocally decrease. Total <span class="hlt">crossovers</span> measured by chiasmata were unchanged when heterozygosity was varied, consistent with homeostatic control. We tested the effects of heterozygosity in mutants where the balance of interfering and non-interfering <span class="hlt">crossover</span> repair is altered. <span class="hlt">Crossover</span> remodeling at homozygosity-heterozygosity junctions requires interference, and non-interfering repair is inefficient in heterozygous regions. As a consequence, heterozygous regions show stronger <span class="hlt">crossover</span> interference. Our findings reveal how varying homolog polymorphism patterns can shape meiotic recombination. DOI: http://dx.doi.org/10.7554/eLife.03708.001 PMID:25815584</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvB..95b4103C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvB..95b4103C"><span>Ordering and dimensional <span class="hlt">crossovers</span> in metallic glasses and liquids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, David Z.; An, Qi; Goddard, William A.; Greer, Julia R.</p> <p>2017-01-01</p> <p>The atomic-level structures of liquids and glasses are amorphous, lacking long-range order. We characterize the atomic structures by integrating radial distribution functions (RDF) from molecular dynamics (MD) simulations for several metallic liquids and glasses: C u46Z r54 , N i80A l20 , N i33.3Z r66.7 , and P d82S i18 . Resulting cumulative coordination numbers (CN) show that metallic liquids have a dimension of d =2.55 ±0.06 from the center atom to the first coordination shell and metallic glasses have d =2.71 ±0.04 , both less than 3. Between the first and second coordination shells, both phases <span class="hlt">crossover</span> to a dimension of d =3 , as for a crystal. Observations from discrete atom center-of-mass position counting are corroborated by continuously counting Cu glass- and liquid-phase atoms on an artificial grid, which accounts for the occupied atomic volume. Results from Cu grid analysis show short-range d =2.65 for Cu liquid and d =2.76 for Cu glass. Cu grid structures <span class="hlt">crossover</span> to d =3 at ξ ˜8 Å (˜3 atomic diameters). We study the evolution of local structural dimensions during quenching and discuss its correlation with the glass transition phenomenon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5133552','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5133552"><span>Spin-<span class="hlt">Crossover</span> Materials towards Microwave Radiation Switches</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kucheriv, Olesia I.; Oliynyk, Viktor V.; Zagorodnii, Volodymyr V.; Launets, Vilen L.; Gural’skiy, Il’ya A.</p> <p>2016-01-01</p> <p>Microwave electromagnetic radiation that ranges from one meter to one millimetre wavelengths is finding numerous applications for wireless communication, navigation and detection, which makes materials able to tune microwave radiation getting widespread interest. Here we offer a new way to tune GHz frequency radiation by using spin-<span class="hlt">crossover</span> complexes that are known to change their various physical properties under the influence of diverse external stimuli. As a result of electronic re-configuration process, microwave absorption properties differ for high spin and low spin forms of the complex. The evolution of a microwave absorption spectrum for the switchable compound within the region of thermal transition indicates that the high-spin and the low-spin forms are characterized by a different attenuation of electromagnetic waves. Absorption and reflection coefficients were found to be higher in the high-spin state comparing to the low-spin state. These results reveal a considerable potential for the implementation of spin-<span class="hlt">crossover</span> materials into different elements of microwave signal switching and wireless communication. PMID:27910956</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18851199','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18851199"><span><span class="hlt">Crossover</span> from attractive to repulsive Casimir forces and vice versa.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schmidt, Felix M; Diehl, H W</p> <p>2008-09-05</p> <p>Systems described by an O(n) symmetrical varphi;{4} Hamiltonian are considered in a d-dimensional film geometry at their bulk critical points. The critical Casimir forces between the film's boundary planes B_{j}, j=1,2, are investigated as functions of film thickness L for generic symmetry-preserving boundary conditions partial differential_{n}phi=c[over composite function]_{j}phi. The L-dependent part of the reduced excess free energy per cross-sectional area takes the scaling form f_{res} approximately D(c_{1}L;{Phi/nu},c_{2}L;{Phi/nu})/L;{d-1} when d<4, where c_{i} are scaling fields associated with the variables c[over composite function]_{i} and Phi is a surface <span class="hlt">crossover</span> exponent. Explicit two-loop renormalization group results for the function D(c_{1},c_{2}) at d=4- dimensions are presented. These show that (i) the Casimir force can have either sign, depending on c_{1} and c_{2}, and (ii) for appropriate choices of the enhancements c[over composite function]_{j}, <span class="hlt">crossovers</span> from attraction to repulsion and vice versa occur as L increases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1254897-superconductor-insulator-transition-fermi-bose-crossovers','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1254897-superconductor-insulator-transition-fermi-bose-crossovers"><span>Superconductor-insulator transition and Fermi-Bose <span class="hlt">crossovers</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Loh, Yen Lee; Randeria, Mohit; Trivedi, Nandini; ...</p> <p>2016-05-31</p> <p>The direct transition from an insulator to a superconductor (SC) in Fermi systems is a problem of long-standing interest, which necessarily goes beyond the standard BCS paradigm of superconductivity as a Fermi surface instability. We introduce here a simple, translationally invariant lattice fermion model that undergoes a SC-insulator transition (SIT) and elucidate its properties using analytical methods and quantum Monte Carlo simulations. We show that there is a fermionic band insulator to bosonic insulator <span class="hlt">crossover</span> in the insulating phase and a BCS-to-BEC <span class="hlt">crossover</span> in the SC. The SIT is always found to be from a bosonic insulator to a BEC-likemore » SC, with an energy gap for fermions that remains finite across the SIT. Hence, the energy scales that go critical at the SIT are the gap to pair excitations in the insulator and the superfluid stiffness in the SC. In addition to giving insight into important questions about the SIT in solid-state systems, our model should be experimentally realizable using ultracold fermions in optical lattices.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21456965','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21456965"><span>Dimensional <span class="hlt">crossover</span> of a boson gas in multilayers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Salas, P.; Sevilla, F. J.; Fortes, M.; Solis, M. A.; Llano, M. de; Camacho, A.</p> <p>2010-09-15</p> <p>We obtain the thermodynamic properties for a noninteracting Bose gas constrained on multilayers modeled by a periodic Kronig-Penney delta potential in one direction and allowed to be free in the other two directions. We report Bose-Einstein condensation (BEC) critical temperatures, chemical potential, internal energy, specific heat, and entropy for different values of a dimensionless impenetrability P{>=}0 between layers. The BEC critical temperature T{sub c} coincides with the ideal gas BEC critical temperature T{sub 0} when P=0 and rapidly goes to zero as P increases to infinity for any finite interlayer separation. The specific heat C{sub V} as a function of absolute temperature T for finite P and plane separation a exhibits one minimum and one or two maxima in addition to the BEC, for temperatures larger than that of BEC T{sub c}. This highlights the effects due to particle confinement. We then discuss a distinctive dimensional <span class="hlt">crossover</span> of the system through the specific heat behavior driven by the magnitude of P. For T<T{sub c} the <span class="hlt">crossover</span> is revealed by a change in slope of logC{sub V}(T) and when T>T{sub c}, it is exhibited by a broad minimum in C{sub V}(T).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14995539','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14995539"><span>Dimensional <span class="hlt">crossover</span> and universal roughness distributions in Barkhausen noise.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>de Queiroz, S L A</p> <p>2004-02-01</p> <p>We investigate the dimensional <span class="hlt">crossover</span> of scaling properties of avalanches (domain-wall jumps) in a single-interface model, used for the description of Barkhausen noise in disordered magnets. By varying the transverse aspect ratio A=L(y)/L(x) of simulated samples, the system dimensionality changes from two to three. We find that perturbing away from d=2 is a relevant field. The exponent tau characterizing the power-law scaling of avalanche distributions varies between 1.06(1) for d=2 and 1.275(15) for d=3, according to a <span class="hlt">crossover</span> function f(x), x identical with (L-1x)(phi)/A, with phi=0.95(3). We discuss the possible relevance of our results to the interpretation of thin-film measurements of Barkhausen noise. We also study the probability distributions of interface roughness, sampled among successive equilibrium configurations in the Barkhausen noise regime. Attempts to fit our data to the class of universality distributions associated to 1/f(alpha) noise give alpha approximately 1-1.1 for d=2 and 3 (provided that suitable boundary conditions are used in the latter case).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22899697','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22899697"><span>Analysis of Poisson frequency data under a simple <span class="hlt">crossover</span> trial.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lui, Kung-Jong; Chang, Kuang-Chao</p> <p>2016-02-01</p> <p>When the frequency of occurrence for an event of interest follows a Poisson distribution, we develop asymptotic and exact procedures for testing non-equality, non-inferiority and equivalence, as well as asymptotic and exact interval estimators for the ratio of mean frequencies between two treatments under a simple <span class="hlt">crossover</span> design. Using Monte Carlo simulations, we evaluate the performance of these test procedures and interval estimators in a variety of situations. We note that all asymptotic test procedures developed here can generally perform well with respect to Type I error and can be preferable to the exact test procedure with respect to power if the number of patients per group is moderate or large. We further find that in these cases the asymptotic interval estimator with the logarithmic transformation can be more precise than the exact interval estimator without sacrificing the accuracy with respect to the coverage probability. However, the exact test procedure and exact interval estimator can be of use when the number of patients per group is small. We use a double-blind randomized <span class="hlt">crossover</span> trial comparing salmeterol with a placebo in exacerbations of asthma to illustrate the practical use of these estimators.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000059233','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000059233"><span>Low <span class="hlt">Crossover</span> Polymer Electrolyte Membranes for Direct Methanol Fuel Cells</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Prakash, G. K. Surya; Smart, Marshall; Atti, Anthony R.; Olah, George A.; Narayanan, S. R.; Valdez, T.; Surampudi, S.</p> <p>1996-01-01</p> <p>Direct Methanol Fuel Cells (DMFC's) using polymer electrolyte membranes are promising power sources for portable and vehicular applications. State of the art technology using Nafion(R) 117 membranes (Dupont) are limited by high methanol permeability and cost, resulting in reduced fuel cell efficiencies and impractical commercialization. Therefore, much research in the fuel cell field is focused on the preparation and testing of low <span class="hlt">crossover</span> and cost efficient polymer electrolyte membranes. The University of Southern California in cooperation with the Jet Propulsion Laboratory is focused on development of such materials. Interpenetrating polymer networks are an effective method used to blend polymer systems without forming chemical links. They provide the ability to modify physical and chemical properties of polymers by optimizing blend compositions. We have developed a novel interpenetrating polymer network based on poly (vinyl - difluoride)/cross-linked polystyrenesulfonic acid polymer composites (PVDF PSSA). Sulfonation of polystyrene accounts for protonic conductivity while the non-polar, PVDF backbone provides structural integrity in addition to methanol rejection. Precursor materials were prepared and analyzed to characterize membrane crystallinity, stability and degree of interpenetration. USC JPL PVDF-PSSA membranes were also characterized to determine methanol permeability, protonic conductivity and sulfur distribution. Membranes were fabricated into membrane electrode assemblies (MEA) and tested for single cell performance. Tests include cell performance over a wide range of temperatures (20 C - 90 C) and cathode conditions (ambient Air/O2). Methanol <span class="hlt">crossover</span> values are measured in situ using an in-line CO2 analyzer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4698653','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4698653"><span>Metal-to-insulator <span class="hlt">crossover</span> in alkali doped zeolite</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Igarashi, Mutsuo; Jeglič, Peter; Krajnc, Andraž; Žitko, Rok; Nakano, Takehito; Nozue, Yasuo; Arčon, Denis</p> <p>2016-01-01</p> <p>We report a systematic nuclear magnetic resonance investigation of the 23Na spin-lattice relaxation rate, 1/T1, in sodium loaded low-silica X (LSX) zeolite, Nan/Na12-LSX, for various loading levels of sodium atoms n across the metal-to-insulator <span class="hlt">crossover</span>. For high loading levels of n ≥ 14.2, 1/T1T shows nearly temperature-independent behaviour between 10 K and 25 K consistent with the Korringa relaxation mechanism and the metallic ground state. As the loading levels decrease below n ≤ 11.6, the extracted density of states (DOS) at the Fermi level sharply decreases, although a residual DOS at Fermi level is still observed even in the samples that lack the metallic Drude-peak in the optical reflectance. The observed <span class="hlt">crossover</span> is a result of a complex loading-level dependence of electric potential felt by the electrons confined to zeolite cages, where the electronic correlations and disorder both play an important role. PMID:26725368</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26668366','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26668366"><span>Recombination patterns in maize reveal limits to <span class="hlt">crossover</span> homeostasis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sidhu, Gaganpreet K; Fang, Celestia; Olson, Mischa A; Falque, Matthieu; Martin, Olivier C; Pawlowski, Wojciech P</p> <p>2015-12-29</p> <p>During meiotic recombination, double-strand breaks (DSBs) are formed in chromosomal DNA and then repaired as either <span class="hlt">crossovers</span> (COs) or non-<span class="hlt">crossovers</span> (NCOs). In most taxa, the number of DSBs vastly exceeds the number of COs. COs are required for generating genetic diversity in the progeny, as well as proper chromosome segregation. Their formation is tightly controlled so that there is at least one CO per pair of homologous chromosomes whereas the maximum number of COs per chromosome pair is fairly limited. One of the main mechanisms controlling the number of recombination events per meiosis is CO homeostasis, which maintains a stable CO number even when the DSB number is dramatically altered. The existence of CO homeostasis has been reported in several species, including mouse, yeast, and Caenorhabditis elegans. However, it is not known whether homeostasis exists in the same form in all species. In addition, the studies of homeostasis have been conducted using mutants and/or transgenic lines exhibiting fairly severe meiotic phenotypes, and it is unclear how important homeostasis is under normal physiological conditions. We found that, in maize, CO control is robust only to ensure one CO per chromosome pair. However, once this limit is reached, the CO number is linearly related to the DSB number. We propose that CO control is a multifaceted process whose different aspects have a varying degree of importance in different species.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27046666','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27046666"><span>Chaos based <span class="hlt">crossover</span> and mutation for securing DICOM image.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ravichandran, Dhivya; Praveenkumar, Padmapriya; Balaguru Rayappan, John Bosco; Amirtharajan, Rengarajan</p> <p>2016-05-01</p> <p>This paper proposes a novel encryption scheme based on combining multiple chaotic maps to ensure the safe transmission of medical images. The proposed scheme uses three chaotic maps namely logistic, tent and sine maps. To achieve an efficient encryption, the proposed chao-cryptic system employs a bio-inspired <span class="hlt">crossover</span> and mutation units to confuse and diffuse the Digital Imaging and Communications in Medicine (DICOM) image pixels. The <span class="hlt">crossover</span> unit extensively permutes the image pixels row-wise and column-wise based on the chaotic key streams generated from the Combined Logistic-Tent (CLT) system. Prior to mutation, the pixels of the crossed over image are decomposed into two images with reduced bit depth. The decomposed images are then mutated by XOR operation with quantized chaotic sequences from Combined Logistic-Sine (CLS) system. In order to validate the sternness of the proposed algorithm, the developed chao-cryptic scheme is subjected to various security analyses such as statistical, differential, key space, key sensitivity, intentional cropping attack and chosen plaintext attack analyses. The experimental results prove the proposed DICOM cryptosystem has achieved a desirable amount of protection for real time medical image security applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014IJMPB..2850054M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014IJMPB..2850054M"><span>Bcs-Bec <span class="hlt">Crossover</span> Without Appeal to Scattering Length Theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Malik, G. P.</p> <p>2014-01-01</p> <p>BCS-BEC (an acronym formed from Bardeen, Cooper, Schrieffer and Bose-Einstein condensation) <span class="hlt">crossover</span> physics has customarily been addressed in the framework of the scattering length theory (SLT), which requires regularization/renormalization of equations involving infinities. This paper gives a frame by frame picture, as it were, of the <span class="hlt">crossover</span> scenario without appealing to SLT. While we believe that the intuitive approach followed here will make the subject accessible to a wider readership, we also show that it sheds light on a feature that has not been under the purview of the customary approach: the role of the hole-hole scatterings vis-à-vis the electron-electron scatterings as one goes from the BCS to the BEC end. More importantly, we show that there are critical values of the concentration (n)and the interaction parameter (λ) at which the condensation of Cooper pairs takes place; this is a finding in contrast with the view that such pairs are automatically condensed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27676242','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27676242"><span>Speed behaviour in work zone <span class="hlt">crossovers</span>. A driving simulator study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Domenichini, Lorenzo; La Torre, Francesca; Branzi, Valentina; Nocentini, Alessandro</p> <p>2017-01-01</p> <p>Reductions in speed and, more critically, in speed variability between vehicles are considered an important factor to reduce crash risk in work zones. This study was designed to evaluate in a virtual environment the drivers' behaviour in response to nine different configurations of a motorway <span class="hlt">crossover</span> work zone. Specifically, the speed behaviour through a typical <span class="hlt">crossover</span> layout, designed in accordance with the Italian Ministerial Decree 10 July 2002, was compared with that of eight alternative configurations which differ in some characteristics such as the sequence of speed limits, the median opening width and the lane width. The influence of variable message signs, of channelizing devices and of perceptual treatments based on Human Factor principles were also tested. Forty-two participants drove in driving simulator scenarios while data on their speeds and decelerations were collected. The results indicated that drivers' speeds are always higher than the temporary posted speed limits for all configurations and that speeds decreases significantly only within the by-passes. However the implementation of higher speed limits, together with a wider median opening and taller channelization devices led to a greater homogeneity of the speeds adopted by the drivers. The presence of perceptual measures generally induced both the greatest homogenization of speeds and the largest reductions in mean speed values. Copyright © 2016 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27910956','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27910956"><span>Spin-<span class="hlt">Crossover</span> Materials towards Microwave Radiation Switches.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kucheriv, Olesia I; Oliynyk, Viktor V; Zagorodnii, Volodymyr V; Launets, Vilen L; Gural'skiy, Il'ya A</p> <p>2016-12-02</p> <p>Microwave electromagnetic radiation that ranges from one meter to one millimetre wavelengths is finding numerous applications for wireless communication, navigation and detection, which makes materials able to tune microwave radiation getting widespread interest. Here we offer a new way to tune GHz frequency radiation by using spin-<span class="hlt">crossover</span> complexes that are known to change their various physical properties under the influence of diverse external stimuli. As a result of electronic re-configuration process, microwave absorption properties differ for high spin and low spin forms of the complex. The evolution of a microwave absorption spectrum for the switchable compound within the region of thermal transition indicates that the high-spin and the low-spin forms are characterized by a different attenuation of electromagnetic waves. Absorption and reflection coefficients were found to be higher in the high-spin state comparing to the low-spin state. These results reveal a considerable potential for the implementation of spin-<span class="hlt">crossover</span> materials into different elements of microwave signal switching and wireless communication.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApSS..353.1143G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApSS..353.1143G"><span>Observation of a <span class="hlt">crossover</span> in kinetic aggregation of Palladium colloids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghafari, M.; Ranjbar, M.; Rouhani, S.</p> <p>2015-10-01</p> <p>We use field emission scanning electron microscope (FE-SEM) to investigate the growth of palladium colloids over the surface of thin films of WO3/glass. The film is prepared by Pulsed Laser Deposition (PLD) at different temperatures. A PdCl2 (aq) droplet is injected on the surface and in the presence of steam hydrogen the droplet is dried through a reduction reaction process. Two distinct aggregation regimes of palladium colloids are observed over the substrates. We argue that the change in aggregation dynamics emerges when the measured water drop Contact Angel (CA) for the WO3/glass thin films passes a certain threshold value, namely CA ≈ 46°, where a <span class="hlt">crossover</span> in kinetic aggregation of palladium colloids occurs. Our results suggest that the mass fractal dimension of palladium aggregates follows a power-law behavior. The fractal dimension (Df) in the fast aggregation regime, where the measured CA values vary from 27° up to 46° according to different substrate deposition temperatures, is Df = 1.75(± 0.02) - the value of Df is in excellent agreement with kinetic aggregation of other colloidal systems in fast aggregation regime. Whereas for the slow aggregation regime, with CA = 58°, the fractal dimension changes abruptly to Df = 1.92(± 0.03). We have also used a modified Box-Counting method to calculate fractal dimension of gray-level images and observe that the <span class="hlt">crossover</span> at around CA ≈ 46° remains unchanged.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...618682I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...618682I"><span>Metal-to-insulator <span class="hlt">crossover</span> in alkali doped zeolite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Igarashi, Mutsuo; Jeglič, Peter; Krajnc, Andraž; Žitko, Rok; Nakano, Takehito; Nozue, Yasuo; Arčon, Denis</p> <p>2016-01-01</p> <p>We report a systematic nuclear magnetic resonance investigation of the 23Na spin-lattice relaxation rate, 1/T1, in sodium loaded low-silica X (LSX) zeolite, Nan/Na12-LSX, for various loading levels of sodium atoms n across the metal-to-insulator <span class="hlt">crossover</span>. For high loading levels of n ≥ 14.2, 1/T1T shows nearly temperature-independent behaviour between 10 K and 25 K consistent with the Korringa relaxation mechanism and the metallic ground state. As the loading levels decrease below n ≤ 11.6, the extracted density of states (DOS) at the Fermi level sharply decreases, although a residual DOS at Fermi level is still observed even in the samples that lack the metallic Drude-peak in the optical reflectance. The observed <span class="hlt">crossover</span> is a result of a complex loading-level dependence of electric potential felt by the electrons confined to zeolite cages, where the electronic correlations and disorder both play an important role.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005PhRvB..72u4408G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005PhRvB..72u4408G"><span>Spin <span class="hlt">crossover</span> in [ MnIII (pyrol)3 tren] probed by high-pressure and low-temperature x-ray diffraction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guionneau, Philippe; Marchivie, Mathieu; Garcia, Yann; Howard, Judith A. K.; Chasseau, Daniel</p> <p>2005-12-01</p> <p>The interplay between the solid-state spin-<span class="hlt">crossover</span> features and the structural properties is analyzed for the [MnIII(pyrol)3tren] complex on the basis of high-pressure and low-temperature single-crystal x-ray-diffraction <span class="hlt">experiments</span>. In particular, the low-temperature ( 30K , 105Pa ) low spin crystal structure is compared to the low-temperature ( 60K , 105Pa ) high spin and to the high-pressure ( 293K , 1.00GPa ) high spin crystal structures. The low-temperature structural properties show the structural modifications due to the spin <span class="hlt">crossover</span> in a Mn(III) complex. Comparison of these structural modifications to those described for mononuclear Fe(II) spin-<span class="hlt">crossover</span> compounds emphasizes significant differences, such as in bond length variation and polyhedron distortion, for example. Elsewhere, analysis of the high-pressure data shows that the internal stress on the metal ion is not the cause of the occurrence of the thermal spin <span class="hlt">crossover</span>, contrary to a general belief.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060031888&hterms=critical+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcritical%2Btheory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060031888&hterms=critical+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcritical%2Btheory"><span>Microgravity Scaling Theory <span class="hlt">Experiment</span>: MISTE science requirements document</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barmatz, M.</p> <p>2001-01-01</p> <p>The goal of the MISTE (Microgravity Scaling Theory <span class="hlt">Experiment</span>) is to provide a stringent test of scaling theory predictions for critical behavior near a liquid-gas critical point both in the asymptomatic and <span class="hlt">crossover</span> regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060031888&hterms=critical+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcritical%2Btheory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060031888&hterms=critical+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcritical%2Btheory"><span>Microgravity Scaling Theory <span class="hlt">Experiment</span>: MISTE science requirements document</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barmatz, M.</p> <p>2001-01-01</p> <p>The goal of the MISTE (Microgravity Scaling Theory <span class="hlt">Experiment</span>) is to provide a stringent test of scaling theory predictions for critical behavior near a liquid-gas critical point both in the asymptomatic and <span class="hlt">crossover</span> regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMMR13A2391T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMMR13A2391T"><span>Systematics of high spin to low spin <span class="hlt">crossovers</span> across the RCoO3 family</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Topsakal, M.; Shukla, G.; Wentzcovitch, R. M.</p> <p>2016-12-01</p> <p>Using density functional theory plus self-consistent Hubbard U (DFT+Usc ) calculations, we have investigated the spin <span class="hlt">crossover</span> phenomenon observed in rare-earth cobaltites RCoO3 (R = Pr - Lu). Previous DFT studies of this series focused on structural and electronic structure variations across the RCoO3 series in which all Co3+ ions are kept in low-spin (LS) state (S=0). Here we manage to stabilize Co3+ ions in the high-spin (HS) state and perform thermodynamics calculations to predict their HS to LS phase diagrams. We show that the early stage of thermally induced spin <span class="hlt">crossover</span> in RCoO 3 can be successfully described by introducing a carefully and legitimately chosen Hubbard U for the HS Co3+. The spin excitation energy (ΔE), as the energy difference of HS and LS states, is calculated across the series. Our calculations show that ΔE increases from PrCoO3 to LuCoO3 in agreement with the increase of spin-state transition temperature observed in <span class="hlt">experiments</span>. We also observed that the Co3+ octahedral volume (or Co-O bond lengths) significantly increases upon excitation into the HS state and we also relate this volume change to ΔE. The octahedral volume expansion (ΔV) increases from PrCoO3 to LuCoO3 : the larger the volume expansion to accommodate HS, the larger the energy required to excite from LS to HS. Furthermore, the Hubbard U parameters presented in this work allow more accurate predictive DFT+U studies on RCoO3 perovskites, especially their magnetic properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22676368','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22676368"><span>Experimental study of <span class="hlt">crossover</span> from capillary to viscous fingering for supercritical CO2-water displacement in a homogeneous pore network.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Ying; Zhang, Changyong; Wei, Ning; Oostrom, Mart; Wietsma, Thomas W; Li, Xiaochun; Bonneville, Alain</p> <p>2013-01-02</p> <p>Carbon sequestration in saline aquifers involves displacing brine from the pore space by supercritical CO(2) (scCO(2)). The displacement process is considered unstable due to the unfavorable viscosity ratio between the invading scCO(2) and the resident brine. The mechanisms that affect scCO(2)-water displacement under reservoir conditions (41 °C, 9 MPa) were investigated in a homogeneous micromodel. A large range of injection rates, expressed as the dimensionless capillary number (Ca), was studied in two sets of <span class="hlt">experiments</span>: discontinuous-rate injection, where the micromodel was saturated with water before each injection rate was imposed, and continuous-rate injection, where the rate was increased after quasi-steady conditions were reached for a certain rate. For the discontinuous-rate <span class="hlt">experiments</span>, capillary fingering and viscous fingering are the dominant mechanisms for low (logCa ≤ -6.61) and high injection rates (logCa ≥ -5.21), respectively. <span class="hlt">Crossover</span> from capillary to viscous fingering was observed for logCa = -5.91 to -5.21, resulting in a large decrease in scCO(2) saturation. The discontinuous-rate experimental results confirmed the decrease in nonwetting fluid saturation during <span class="hlt">crossover</span> from capillary to viscous fingering predicted by numerical simulations by Lenormand et al. (J. Fluid Mech.1988, 189, 165-187). Capillary fingering was the dominant mechanism for all injection rates in the continuous-rate <span class="hlt">experiment</span>, resulting in monotonic increase in scCO(2) saturation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22594415','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22594415"><span>Matrix-assisted relaxation in Fe(phen){sub 2}(NCS){sub 2} spin-<span class="hlt">crossover</span> microparticles, experimental and theoretical investigations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Enachescu, Cristian Stancu, Alexandru; Tanasa, Radu; Tissot, Antoine; Laisney, Jérôme; Boillot, Marie-Laure</p> <p>2016-07-18</p> <p>In this study, we present the influence of the embedding matrix on the relaxation of Fe(phen){sub 2}(NCS){sub 2} (phen = 1,10-phenanthroline) spin-transition microparticles as revealed by <span class="hlt">experiments</span> and provide an explanation within the framework of an elastic model based on a Monte-Carlo method. <span class="hlt">Experiments</span> show that the shape of the high-spin → low-spin relaxation curves is drastically changed when the particles are dispersed in glycerol. This effect was considered in the model by means of interactions between the microparticles and the matrix. A faster start of the relaxation for microparticles embedded in glycerol is due to an initial positive local pressure acting on the edge spin-<span class="hlt">crossover</span> molecules from the matrix side. This local pressure diminishes and eventually becomes negative during relaxation, as an effect of the decrease of the volume of spin-<span class="hlt">crossover</span> microparticles from high-spin to low-spin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4820060','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4820060"><span>Daily Positive Spillover and <span class="hlt">Crossover</span> from Mothers’ Work to Youth Health</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lawson, Katie M.; Davis, Kelly D.; McHale, Susan M.; Hammer, Leslie B.; Buxton, Orfeu M.</p> <p>2016-01-01</p> <p>Prior research shows that employees’ work <span class="hlt">experiences</span> can “spill over” into their family lives and “cross over” to affect family members. Expanding on studies that emphasize negative implications of work for family life, this study examined positive work-to-family spillover and positive and negative <span class="hlt">crossover</span> between mothers and their children. Participants were 174 mothers in the extended care (nursing home) industry and their children (ages 9-17), both of whom completed daily diaries on the same, eight, consecutive evenings. On each workday, mothers reported whether they had a positive <span class="hlt">experience</span> at work, youth reported on their mothers’ positive and negative mood after work, and youth rated their own mental (positive and negative affect) and physical health (physical health symptoms, sleep quality, sleep duration). Results of two-level models showed that mothers’ positive mood after work, on average, was directly related to youth reports of more positive affect, better sleep quality, and longer sleep duration. In addition, mothers with more positive work <span class="hlt">experiences</span>, on average, displayed less negative mood after work, and in turn, adolescents reported less negative affect and fewer physical health symptoms. Results are discussed in terms of daily family system dynamics. PMID:25243577</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title50-vol11/pdf/CFR-2011-title50-vol11-sec660-320.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title50-vol11/pdf/CFR-2011-title50-vol11-sec660-320.pdf"><span>50 CFR 660.320 - Open access fishery-<span class="hlt">crossover</span> provisions.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-10-01</p> <p>... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Open access fishery-<span class="hlt">crossover</span> provisions... West Coast Groundfish-Open Access Fisheries § 660.320 Open access fishery—<span class="hlt">crossover</span> provisions. (a) Operating in both limited entry and open access fisheries. See provisions at § 660.60, subpart C. (b...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title50-vol13/pdf/CFR-2012-title50-vol13-sec660-220.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title50-vol13/pdf/CFR-2012-title50-vol13-sec660-220.pdf"><span>50 CFR 660.220 - Fixed gear fishery-<span class="hlt">crossover</span> provisions.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-10-01</p> <p>... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Fixed gear fishery-<span class="hlt">crossover</span> provisions... West Coast Groundfish-Limited Entry Fixed Gear Fisheries § 660.220 Fixed gear fishery—<span class="hlt">crossover</span>... fixed gear fishery....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5358726','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5358726"><span>Natural variation and dosage of the HEI10 meiotic E3 ligase control Arabidopsis <span class="hlt">crossover</span> recombination</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ziolkowski, Piotr A.; Underwood, Charles J.; Lambing, Christophe; Martinez-Garcia, Marina; Lawrence, Emma J.; Ziolkowska, Liliana; Griffin, Catherine; Choi, Kyuha; Franklin, F. Chris H.; Martienssen, Robert A.; Henderson, Ian R.</p> <p>2017-01-01</p> <p>During meiosis, homologous chromosomes undergo <span class="hlt">crossover</span> recombination, which creates genetic diversity and balances homolog segregation. Despite these critical functions, <span class="hlt">crossover</span> frequency varies extensively within and between species. Although natural <span class="hlt">crossover</span> recombination modifier loci have been detected in plants, causal genes have remained elusive. Using natural Arabidopsis thaliana accessions, we identified two major recombination quantitative trait loci (rQTLs) that explain 56.9% of <span class="hlt">crossover</span> variation in Col×Ler F2 populations. We mapped rQTL1 to semidominant polymorphisms in HEI10, which encodes a conserved ubiquitin E3 ligase that regulates <span class="hlt">crossovers</span>. Null hei10 mutants are haploinsufficient, and, using genome-wide mapping and immunocytology, we show that transformation of additional HEI10 copies is sufficient to more than double euchromatic <span class="hlt">crossovers</span>. However, heterochromatic centromeres remained recombination-suppressed. The strongest HEI10-mediated <span class="hlt">crossover</span> increases occur in subtelomeric euchromatin, which is reminiscent of sex differences in Arabidopsis recombination. Our work reveals that HEI10 naturally limits Arabidopsis <span class="hlt">crossovers</span> and has the potential to influence the response to selection. PMID:28223312</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=crossover+AND+design&pg=7&id=ED143310','ERIC'); return false;" href="http://eric.ed.gov/?q=crossover+AND+design&pg=7&id=ED143310"><span>A <span class="hlt">Cross-Over</span> Experimental Design for Testing Audiovisual Training Materials.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Stolovitch, Harold D.; Bordeleau, Pierre</p> <p></p> <p>This paper contains a description of the <span class="hlt">cross-over</span> type of experimental design as well as a case study of its use in field testing audiovisual materials related to teaching handicapped children. Increased efficiency is an advantage of the <span class="hlt">cross-over</span> design, while difficulty in selecting similar format audiovisual materials for field testing is a…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24595585','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24595585"><span>Methods for adjusting for bias due to <span class="hlt">crossover</span> in oncology trials.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ishak, K Jack; Proskorovsky, Irina; Korytowsky, Beata; Sandin, Rickard; Faivre, Sandrine; Valle, Juan</p> <p>2014-06-01</p> <p>Trials of new oncology treatments often involve a <span class="hlt">crossover</span> element in their design that allows patients receiving the control treatment to <span class="hlt">crossover</span> to receive the experimental treatment at disease progression or when sufficient evidence about the efficacy of the new treatment is achieved. <span class="hlt">Crossover</span> leads to contamination of the initial randomized groups due to a mixing of the effects of the control and experimental treatments in the reference group. This is further complicated by the fact that <span class="hlt">crossover</span> is often a very selective process whereby patients who switch treatment have a different prognosis than those who do not. Standard statistical techniques, including those that attempt to account for the treatment switch, cannot fully adjust for the bias introduced by <span class="hlt">crossover</span>. Specialized methods such as rank-preserving structural failure time (RPSFT) models and inverse probability of censoring weighted (IPCW) analyses are designed to deal with selective treatment switching and have been increasingly applied to adjust for <span class="hlt">crossover</span>. We provide an overview of the <span class="hlt">crossover</span> problem and highlight circumstances under which it is likely to cause bias. We then describe the RPSFT and IPCW methods and explain how these methods adjust for the bias, highlighting the assumptions invoked in the process. Our aim is to facilitate understanding of these complex methods using a case study to support explanations. We also discuss the implications of <span class="hlt">crossover</span> adjustment on cost-effectiveness results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title50-vol13/pdf/CFR-2013-title50-vol13-sec660-220.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title50-vol13/pdf/CFR-2013-title50-vol13-sec660-220.pdf"><span>50 CFR 660.220 - Fixed gear fishery-<span class="hlt">crossover</span> provisions.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-10-01</p> <p>... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Fixed gear fishery-<span class="hlt">crossover</span> provisions... West Coast Groundfish-Limited Entry Fixed Gear Fisheries § 660.220 Fixed gear fishery—<span class="hlt">crossover</span>... fixed gear fishery. ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title50-vol13/pdf/CFR-2014-title50-vol13-sec660-220.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title50-vol13/pdf/CFR-2014-title50-vol13-sec660-220.pdf"><span>50 CFR 660.220 - Fixed gear fishery-<span class="hlt">crossover</span> provisions.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-10-01</p> <p>... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Fixed gear fishery-<span class="hlt">crossover</span> provisions... West Coast Groundfish-Limited Entry Fixed Gear Fisheries § 660.220 Fixed gear fishery—<span class="hlt">crossover</span>... fixed gear fishery. ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title49-vol4/pdf/CFR-2011-title49-vol4-sec218-107.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title49-vol4/pdf/CFR-2011-title49-vol4-sec218-107.pdf"><span>49 CFR 218.107 - Additional operational requirements for hand-operated <span class="hlt">crossover</span> switches.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-10-01</p> <p>... 49 Transportation 4 2011-10-01 2011-10-01 false Additional operational requirements for hand... hand-operated <span class="hlt">crossover</span> switches. (a) Each railroad shall adopt and comply with an operating rule which... requirements of this section. (b) Hand-operated <span class="hlt">crossover</span> switches, generally. Both hand-operated switches of a...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title49-vol4/pdf/CFR-2013-title49-vol4-sec218-107.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title49-vol4/pdf/CFR-2013-title49-vol4-sec218-107.pdf"><span>49 CFR 218.107 - Additional operational requirements for hand-operated <span class="hlt">crossover</span> switches.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-10-01</p> <p>... 49 Transportation 4 2013-10-01 2013-10-01 false Additional operational requirements for hand... hand-operated <span class="hlt">crossover</span> switches. (a) Each railroad shall adopt and comply with an operating rule which... requirements of this section. (b) Hand-operated <span class="hlt">crossover</span> switches, generally. Both hand-operated switches of a...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title49-vol4/pdf/CFR-2010-title49-vol4-sec218-107.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title49-vol4/pdf/CFR-2010-title49-vol4-sec218-107.pdf"><span>49 CFR 218.107 - Additional operational requirements for hand-operated <span class="hlt">crossover</span> switches.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-10-01</p> <p>... 49 Transportation 4 2010-10-01 2010-10-01 false Additional operational requirements for hand... hand-operated <span class="hlt">crossover</span> switches. (a) Each railroad shall adopt and comply with an operating rule which... requirements of this section. (b) Hand-operated <span class="hlt">crossover</span> switches, generally. Both hand-operated switches of a...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title49-vol4/pdf/CFR-2014-title49-vol4-sec218-107.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title49-vol4/pdf/CFR-2014-title49-vol4-sec218-107.pdf"><span>49 CFR 218.107 - Additional operational requirements for hand-operated <span class="hlt">crossover</span> switches.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-10-01</p> <p>... 49 Transportation 4 2014-10-01 2014-10-01 false Additional operational requirements for hand... hand-operated <span class="hlt">crossover</span> switches. (a) Each railroad shall adopt and comply with an operating rule which... requirements of this section. (b) Hand-operated <span class="hlt">crossover</span> switches, generally. Both hand-operated switches of a...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title49-vol4/pdf/CFR-2012-title49-vol4-sec218-107.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title49-vol4/pdf/CFR-2012-title49-vol4-sec218-107.pdf"><span>49 CFR 218.107 - Additional operational requirements for hand-operated <span class="hlt">crossover</span> switches.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-10-01</p> <p>... 49 Transportation 4 2012-10-01 2012-10-01 false Additional operational requirements for hand... hand-operated <span class="hlt">crossover</span> switches. (a) Each railroad shall adopt and comply with an operating rule which... requirements of this section. (b) Hand-operated <span class="hlt">crossover</span> switches, generally. Both hand-operated switches of a...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=job+AND+demands&pg=7&id=EJ723874','ERIC'); return false;" href="http://eric.ed.gov/?q=job+AND+demands&pg=7&id=EJ723874"><span>Spillover and <span class="hlt">Crossover</span> of Exhaustion and Life Satisfaction among Dual-Earner Parents</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Demerouti, Evangelia; Bakker, Arnold B.; Schaufeli, Wilmar B.</p> <p>2005-01-01</p> <p>This study integrates spillover research of stress transferring from work to home and <span class="hlt">crossover</span> research of strains transferring from one spouse to another. A spillover and <span class="hlt">crossover</span> model was tested among 191 (couples of) dual-earner parents. For both males and females, it was hypothesized that (self-reported and partners' rating of)…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title50-vol9/pdf/CFR-2010-title50-vol9-sec660-320.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title50-vol9/pdf/CFR-2010-title50-vol9-sec660-320.pdf"><span>50 CFR 660.320 - Open access fishery-<span class="hlt">crossover</span> provisions.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-10-01</p> <p>... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Open access fishery-<span class="hlt">crossover</span> provisions... West Coast Groundfish-Open Access Fisheries § 660.320 Open access fishery—<span class="hlt">crossover</span> provisions. (a) Operating in both limited entry and open access fisheries. See provisions at § 660.60, subpart C. (b...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22486184','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22486184"><span>A <span class="hlt">crossover</span> in anisotropic nanomechanochemistry of van der Waals crystals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shimamura, Kohei; Misawa, Masaaki; Li, Ying; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya; Shimojo, Fuyuki</p> <p>2015-12-07</p> <p>In nanoscale mechanochemistry, mechanical forces selectively break covalent bonds to essentially control chemical reactions. An archetype is anisotropic detonation of layered energetic molecular crystals bonded by van der Waals (vdW) interactions. Here, quantum molecular dynamics simulations reveal a <span class="hlt">crossover</span> of anisotropic nanomechanochemistry of vdW crystal. Within 10{sup −13} s from the passage of shock front, lateral collision produces NO{sub 2} via twisting and bending of nitro-groups and the resulting inverse Jahn-Teller effect, which is mediated by strong intra-layer hydrogen bonds. Subsequently, as we transition from heterogeneous to homogeneous mechanochemical regimes around 10{sup −12} s, shock normal to multilayers becomes more reactive, producing H{sub 2}O assisted by inter-layer N-N bond formation. These time-resolved results provide much needed atomistic understanding of nanomechanochemistry that underlies a wider range of technologies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10180792','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10180792"><span><span class="hlt">Crossover</span> from BCS to Bose superconductivity: A functional integral approach</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Randeria, M.; Sa de Melo, C.A.R.; Engelbrecht, J.R.</p> <p>1993-04-01</p> <p>We use a functional integral formulation to study the <span class="hlt">crossover</span> from cooperative Cooper pairing to the formation and condensation of tightly bound pairs in a 3D continuum model of fermions with attractive interactions. The inadequacy of a saddle point approximation with increasing coupling is pointed out, and the importance of temporal (quantum) fluctuations for normal state properties at intermediate and strong coupling is emphasized. In addition to recovering the Nozieres-Schmitt-Pink interpolation scheme for T{sub c}, and the Leggett variational results for T = 0, we also present results for evolution of the time-dependent Ginzburg-Landau equation and collective mode spectrum as a function of the coupling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998moeg.book..121P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998moeg.book..121P"><span>Scaling and <span class="hlt">crossovers</span> in models for thin film growth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pimpinelli, Alberto; Jensen, Pablo; Larralde, Hernán Peyla, Philippe</p> <p></p> <p>A self-contained review of the scaling arguments used for computing the maximum island density in adatom aggregation on a substrate during thin-film growth, is presented. We show how a general argument can be formulated, which applies to all physical situations, and allows to re-derive known results, as well as generalizations and new ones. When several processes, such as island aggregation, capture by pre-existing steps, adatom desorption, are in competition, this scaling argument allows to determine the appropriate scaling parameters, and yields approximate analytic forms of the <span class="hlt">crossover</span> scaling functions. The scaling form of the growth velocity of a film when adatom desorption is present, is investigated. Surprisingly, a strict analogy between layer-by-layer growth on a high-symmetry substrate and step flow on a vicinal substrate, is found.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21902299','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21902299"><span><span class="hlt">Crossover</span> from adiabatic to antiadiabatic quantum pumping with dissipation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pellegrini, Franco; Negri, C; Pistolesi, F; Manini, Nicola; Santoro, Giuseppe E; Tosatti, Erio</p> <p>2011-08-05</p> <p>Quantum pumping, in its different forms, is attracting attention from different fields, from fundamental quantum mechanics, to nanotechnology, to superconductivity. We investigate the <span class="hlt">crossover</span> of quantum pumping from the adiabatic to the antiadiabatic regime in the presence of dissipation, and find general and explicit analytical expressions for the pumped current in a minimal model describing a system with the topology of a ring forced by a periodic modulation of frequency ω. The solution allows following in a transparent way the evolution of pumped dc current from much smaller to much larger ω values than the other relevant energy scale, the energy splitting introduced by the modulation. We find and characterize a temperature-dependent optimal value of the frequency for which the pumped current is maximal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9655E..3AP','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9655E..3AP"><span>Metal ion sensing solution containing double <span class="hlt">crossover</span> DNA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, Byeongho; Dugasani, Sreekantha R.; Cho, Youngho; Oh, Juyeong; Kim, Chulki; Seo, Min Ah; Lee, Taikjin; Jhon, Young Miin; Woo, Deok Ha; Lee, Seok; Jun, Seong Chan; Park, Sung Ha; Kim, Jae Hun</p> <p>2015-07-01</p> <p>The current study describes metal ion sensing with double <span class="hlt">crossover</span> DNAs (DX1 and DX2), artificially designed as a platform of doping. The sample for sensing is prepared by a facile annealing method to grow the DXs lattice on a silicon/silicon oxide. Adding and incubating metal ion solution with the sensor substrate into the micro-tube lead the optical property change. Photoluminescence (PL) is employed for detecting the concentration of metal ion in the specimen. We investigated PL emission for sensor application with the divalent copper. In the range from 400 to 650 nm, the PL features of samples provide significantly different peak positions with excitation and emission detection. Metal ions contribute to modify the optical characteristics of DX with structural and functional change, which results from the intercalation of them into hydrogen bonding positioned at the center of double helix. The PL intensity is decreased gradually after doping copper ion in the DX tile on the substrate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26538182','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26538182"><span>Optimal adaptive sequential designs for <span class="hlt">crossover</span> bioequivalence studies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xu, Jialin; Audet, Charles; DiLiberti, Charles E; Hauck, Walter W; Montague, Timothy H; Parr, Alan F; Potvin, Diane; Schuirmann, Donald J</p> <p>2016-01-01</p> <p>In prior works, this group demonstrated the feasibility of valid adaptive sequential designs for <span class="hlt">crossover</span> bioequivalence studies. In this paper, we extend the prior work to optimize adaptive sequential designs over a range of geometric mean test/reference ratios (GMRs) of 70-143% within each of two ranges of intra-subject coefficient of variation (10-30% and 30-55%). These designs also introduce a futility decision for stopping the study after the first stage if there is sufficiently low likelihood of meeting bioequivalence criteria if the second stage were completed, as well as an upper limit on total study size. The optimized designs exhibited substantially improved performance characteristics over our previous adaptive sequential designs. Even though the optimized designs avoided undue inflation of type I error and maintained power at ≥ 80%, their average sample sizes were similar to or less than those of conventional single stage designs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhRvB..81v4411W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhRvB..81v4411W"><span>Dimensionality <span class="hlt">crossover</span> and frustrated spin dynamics on a triangular lattice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wikberg, J. M.; Dahbi, M.; Saadoune, I.; Gustafsson, T.; Edström, K.; Svedlindh, P.</p> <p>2010-06-01</p> <p>Investigations of the magnetic behavior of the layered oxide, LiNi0.65Co0.25Mn0.10O2 , through ac and time-dependent susceptibility, dc linear and nonlinear susceptibility as well as neutron-diffraction measurements are presented. A ferrimagneticlike spin ordering appears at 119 K with a spontaneous magnetization coexisting with spin frustration in two dimensions (2D). At lower temperature, a cluster-glass transition is found at 17.4 K indicating a transformation to a completely frustrated state in three dimensions (3D). A dimensionality <span class="hlt">crossover</span> with temperature, from 2D to 3D, in a magnetically frustrated system has been demonstrated. The observed magnetic behavior is believed to originate from a percolating system of spin clusters defined by disordered and frustrated exchange interactions and the findings conform well with predictions of the percolation cluster model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3739003','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3739003"><span>Quantum Corrections <span class="hlt">Crossover</span> and Ferromagnetism in Magnetic Topological Insulators</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bao, Lihong; Wang, Weiyi; Meyer, Nicholas; Liu, Yanwen; Zhang, Cheng; Wang, Kai; Ai, Ping; Xiu, Faxian</p> <p>2013-01-01</p> <p>Revelation of emerging exotic states of topological insulators (TIs) for future quantum computing applications relies on breaking time-reversal symmetry and opening a surface energy gap. Here, we report on the transport response of Bi2Te3 TI thin films in the presence of varying Cr dopants. By tracking the magnetoconductance (MC) in a low doping regime we observed a progressive <span class="hlt">crossover</span> from weak antilocalization (WAL) to weak localization (WL) as the Cr concentration increases. In a high doping regime, however, increasing Cr concentration yields a monotonically enhanced anomalous Hall effect (AHE) accompanied by an increasing carrier density. Our results demonstrate a possibility of manipulating bulk ferromagnetism and quantum transport in magnetic TI, thus providing an alternative way for experimentally realizing exotic quantum states required by spintronic applications. PMID:23928713</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24730796','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24730796"><span><span class="hlt">Crossover</span> behavior of conductivity in a discontinuous percolation model.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kim, Seongmin; Cho, Y S; Araújo, N A M; Kahng, B</p> <p>2014-03-01</p> <p>When conducting bonds are occupied randomly in a two-dimensional square lattice, the conductivity of the system increases continuously as the density of those conducting bonds exceeds the percolation threshold. Such a behavior is well known in percolation theory; however, the conductivity behavior has not been studied yet when the percolation transition is discontinuous. Here we investigate the conductivity behavior through a discontinuous percolation model evolving under a suppressive external bias. Using effective medium theory, we analytically calculate the conductivity behavior as a function of the density of conducting bonds. The conductivity function exhibits a <span class="hlt">crossover</span> behavior from a drastically to a smoothly increasing function beyond the percolation threshold in the thermodynamic limit. The analytic expression fits well our simulation data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21537048','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21537048"><span>Berezinskii-Kosterlitz-Thouless <span class="hlt">crossover</span> in a photonic lattice</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Small, Eran; Pugatch, Rami; Silberberg, Yaron</p> <p>2011-01-15</p> <p>We show that a periodic two-dimensional (2D) photonic lattice with Kerr nonlinearity exhibits a Berezinskii-Kosterlitz-Thouless (BKT) <span class="hlt">crossover</span> associated with a vortex-unbinding transition. We find that averaging over random initial conditions is equivalent to Boltzmann thermal averaging with the discrete nonlinear Schro{center_dot}{center_dot}dinger Hamiltonian. By controlling the initial randomness we can continuously vary the effective temperature. Since this Hamiltonian is in the 2D XY universality class, a BKT transition ensues. We verify this prediction using experimentally accessible observables and find good agreement between theory and simulations. This opens the possibility of experimental access to interesting phase transitions known in condensed matter using nonlinear optics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009CoTPh..51..358M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009CoTPh..51..358M"><span><span class="hlt">Crossover</span> Phenomena in Detrended Fluctuation Analysis Used in Financial Markets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ma, Shi-Hao</p> <p>2009-02-01</p> <p>A systematic analysis of Shanghai and Japan stock indices for the period of Jan. 1984 to Dec. 2005 is performed. After stationarity is verified by ADF (Augmented Dickey-Fuller) test, the power spectrum of the data exhibits a power law decay as a whole characterized by 1/fβ processes with possible long range correlations. Subsequently, by using the method of detrended fluctuation analysis (DFA) of the general volatility in the stock markets, we find that the long-range correlations are occurred among the return series and the <span class="hlt">crossover</span> phenomena exhibit in the results obviously. Further, Shanghai stock market shows long-range correlations in short time scale and shows short-range correlations in long time scale. Whereas, for Japan stock market, the data behaves oppositely absolutely. Last, we compare the varying of scale exponent in large volatility between two stock markets. All results obtained may indicate the possibility of characteristic of multifractal scaling behavior of the financial markets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19778128','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19778128"><span><span class="hlt">Crossover</span> from nucleation to spinodal decomposition in a condensing vapor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wedekind, Jan; Chkonia, Guram; Wölk, Judith; Strey, Reinhard; Reguera, David</p> <p>2009-09-21</p> <p>The mechanism controlling the initial step of a phase transition has a tremendous influence on the emerging phase. We study the <span class="hlt">crossover</span> from a purely nucleation-controlled transition toward spinodal decomposition in a condensing Lennard-Jones vapor using molecular dynamics simulations. We analyze both the kinetics and at the same time the thermodynamics by directly reconstructing the free energy of cluster formation. We estimate the location of the spinodal, which lies at much deeper supersaturations than expected. Moreover, the nucleation barriers we find differ only by a constant from the classical nucleation theory predictions and are in very good agreement with semiempirical scaling relations. In the regime from very small barriers to the spinodal, growth controls the rate of the transition but not its nature because the activation barrier has not yet vanished. Finally, we discuss in detail the influence of the chosen reaction coordinate on the interpretation of such simulation results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009NatMa...8..813B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009NatMa...8..813B"><span>Electrostatic spin <span class="hlt">crossover</span> effect in polar magnetic molecules</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baadji, Nadjib; Piacenza, Manuel; Tugsuz, Tugba; Sala, Fabio Della; Maruccio, Giuseppe; Sanvito, Stefano</p> <p>2009-10-01</p> <p>The magnetic configuration of a nanostructure can be altered by an external magnetic field, by spin-transfer torque or by its magnetoelastic response. Here, we explore an alternative route, namely the possibility of switching the sign of the exchange coupling between two magnetic centres by means of an electric potential. This general effect, which we name electrostatic spin <span class="hlt">crossover</span>, occurs in insulating molecules with super-exchange magnetic interaction and inversion symmetry breaking. As an example we present the case of a family of di-cobaltocene-based molecules. The critical fields for switching, calculated from first principles, are of the order of 1Vnm-1 and can be achieved in two-terminal devices. More crucially, such critical fields can be engineered with an appropriate choice of substituents to add to the basic di-cobaltocene unit. This suggests that an easy chemical strategy for achieving the synthesis of suitable molecules is possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2000055','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2000055"><span>Acupuncture for bronchial asthma? A double-blind <span class="hlt">crossover</span> study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tandon, M K; Soh, P F; Wood, A T</p> <p>1991-03-18</p> <p>The therapeutic effectiveness of classic Chinese acupuncture was compared with "placebo" acupuncture in 15 patients with stable bronchial asthma. The patients received treatments with real and placebo acupuncture in a randomly ordered, subject and evaluator-blind <span class="hlt">crossover</span> fashion twice weekly for five weeks. Both real and placebo treatment periods were preceded by three week periods when no acupuncture was administered. Five patients felt better on real treatment, five patients preferred placebo and five did not feel any improvement on either of the two treatments. Treatment with real acupuncture when compared with no treatment and placebo treatment failed to provide any improvement in daily peak flow rates, asthma symptom scores, number of puffs of beta 2-agonist aerosol use, and pulmonary function results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25089719','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25089719"><span>Factors underlying restricted <span class="hlt">crossover</span> localization in barley meiosis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Higgins, James D; Osman, Kim; Jones, Gareth H; Franklin, F Chris H</p> <p>2014-01-01</p> <p>Meiotic recombination results in the formation of cytological structures known as chiasmata at the sites of genetic <span class="hlt">crossovers</span> (COs). The formation of at least one chiasma/CO between homologous chromosome pairs is essential for accurate chromosome segregation at the first meiotic division as well as for generating genetic variation. Although DNA double-strand breaks, which initiate recombination, are widely distributed along the chromosomes, this is not necessarily reflected in the chiasma distribution. In many species there is a tendency for chiasmata to be distributed in favored regions along the chromosomes, whereas in others, such as barley and some other grasses, chiasma localization is extremely pronounced. Localization of chiasma to the distal regions of barley chromosomes restricts the genetic variation available to breeders. Studies reviewed herein are beginning to provide an explanation for chiasma localization in barley. Moreover, they suggest a potential route to manipulating chiasma distribution that could be of value to plant breeders.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/40230650','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/40230650"><span>Charge <span class="hlt">crossover</span> at the U(1)-Higgs phase transition</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Freire, Filipe; Litim, Daniel F.</p> <p>2001-08-15</p> <p>The type-I region of phase transitions at finite temperature of the U(1)-Higgs theory in 3+1 dimensions is investigated in detail using a Wilsonian renormalization group. We consider, in particular, the quantitative effects induced through the <span class="hlt">crossover</span> of the scale-dependent Abelian charge from the Gaussian to a nontrivial Abelian fixed point. As a result, the strength of the first-order phase transition is weakened. Analytical solutions to approximate flow equations are obtained, and all characteristics of the phase transition are discussed and compared to the results obtained from perturbation theory. In addition, we present a detailed quantitative study regarding the dependence of the physical observables on the coarse-graining scheme. This results in error bars for the regularization scheme (RS) dependence. We find quantitative evidence for an intimate link between the RS dependence and truncations of flow equations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28935973','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28935973"><span>Scaling of Memories and <span class="hlt">Crossover</span> in Glassy Magnets.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Samarakoon, A M; Takahashi, M; Zhang, D; Yang, J; Katayama, N; Sinclair, R; Zhou, H D; Diallo, S O; Ehlers, G; Tennant, D A; Wakimoto, S; Yamada, K; Chern, G-W; Sato, T J; Lee, S-H</p> <p>2017-09-21</p> <p>Glassiness is ubiquitous and diverse in characteristics in nature. Understanding their differences and classification remains a major scientific challenge. Here, we show that scaling of magnetic memories with time can be used to classify magnetic glassy materials into two distinct classes. The systems studied are high temperature superconductor-related materials, spin-orbit Mott insulators, frustrated magnets, and dilute magnetic alloys. Our bulk magnetization measurements reveal that most densely populated magnets exhibit similar memory behavior characterized by a relaxation exponent of [Formula: see text]. This exponent is different from [Formula: see text] of dilute magnetic alloys that was ascribed to their hierarchical and fractal energy landscape, and is also different from [Formula: see text] of the conventional Debye relaxation expected for a spin solid, a state with long range order. Furthermore, our systematic study on dilute magnetic alloys with varying magnetic concentration exhibits <span class="hlt">crossovers</span> among the two glassy states and spin solid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15524929','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15524929"><span>Magic angle effects and angular magnetoresistance oscillations as dimensional <span class="hlt">crossovers</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lebed, A G; Bagmet, N N; Naughton, M J</p> <p>2004-10-08</p> <p>Interference effects between velocity and density of states, which occur as electrons move along open orbits in the extended Brillouin zone in anisotropic conductors, result in a change of wave functions' dimensionality at magic angle (MA) directions of a magnetic field. In particular, these 1D-->2D dimensional <span class="hlt">crossovers</span> result in the appearance of sharp minima in a resistivity component rho perpendicular (H,alpha), perpendicular to conducting layers. This explains the main qualitative features of MA and angular magnetoresistance oscillations' phenomena observed due to the existence of quasi-one-dimensional sheets of Fermi surface in (TMTSF)2X, (DMET-TSeF)2X, and kappa-(ET)2Cu(NCS)(2) conductors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/320924','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/320924"><span>Economic <span class="hlt">crossover</span> parameters for outsourcing water treatment equipment</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sinha, K.; Khan, S.</p> <p>1998-12-31</p> <p>Outsourcing water treatment systems is an attractive alternative to installing permanent systems. The current industry trend favors leased and outsourced systems for demineralized water applications when water demands are small and no pretreatment system is required. This paper provides economic <span class="hlt">crossover</span> parameters for power plant applications, taking life cycle costs into consideration, including operation and maintenance (O and M) and capital costs, auxiliary load and heat rate penalties, O and M personnel requirements, and other economic considerations. Furthermore, the paper establishes ground rules for such comparisons between outsourced and permanent water treatment systems considering demineralization of water as well as impact on other power plant systems. Water production costs and $/1,000 gallon cost parameters for water production are presented, with graphical references to the economic parameters discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10431286','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10431286"><span>The <span class="hlt">crossover</span> of strain from school principals to teachers and vice versa.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Westman, M; Etzion, D</p> <p>1999-07-01</p> <p>The study investigated <span class="hlt">crossover</span> of stress and strain in the workplace on a sample of 47 school principals and 183 teachers in Israeli elementary schools. The main goal of this study was to examine whether the <span class="hlt">crossover</span> effect found among couples in the family also exists in the workplace. A 2nd aim of the study was to unravel the mechanisms that account for the <span class="hlt">crossover</span> process. Using structural equation modeling, the authors found a significant <span class="hlt">crossover</span> of job-induced tension but not of burnout from principals to teachers and vice versa. Being undermined by their principals elevated teachers' burnout and job-induced tension. This is the 1st study to demonstrate <span class="hlt">crossover</span> of strain in the workplace and to discuss the implications of contagious job-induced tension in work environments.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990PhRvA..41.4433N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990PhRvA..41.4433N"><span><span class="hlt">Crossover</span> phenomena in non-Newtonian viscous fingers at a finite viscosity ratio</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nagatani, Takashi</p> <p>1990-04-01</p> <p>A viscous fingering of non-Newtonian fluids at a finite viscosity ratio is considered in order to study the effect of non-Newtonian fluid on <span class="hlt">crossover</span> phenomena. The <span class="hlt">crossover</span> from the fractal pattern to the dense structure is investigated by using a two-parameter position-space renormalization-group method. The global flow diagrams in two-parameter space are obtained. It is found that there are two nontrivial fixed points: the fractal point and the Eden point. When the viscosity ratio is finite, the pattern must eventually cross over to the dense structure. The dependences of the <span class="hlt">crossover</span> phenomena on the parameter k, which describes the different non-Newtonian fluids, are shown. It is found that the non-Newtonian fluids have important effects on the fractal point and the <span class="hlt">crossover</span> line but the <span class="hlt">crossover</span> exponent is independent of the non-Newtonian property.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28133662','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28133662"><span>A luminescent Pt2Fe spin <span class="hlt">crossover</span> complex.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schäfer, Bernhard; Bauer, Thomas; Faus, Isabelle; Wolny, Juliusz A; Dahms, Fabian; Fuhr, Olaf; Lebedkin, Sergei; Wille, Hans-Christian; Schlage, Kai; Chevalier, Katharina; Rupp, Fabian; Diller, Rolf; Schünemann, Volker; Kappes, Manfred M; Ruben, Mario</p> <p>2017-02-14</p> <p>A heterotrinuclear [Pt2Fe] spin <span class="hlt">crossover</span> (SCO) complex was developed and synthesized employing a ditopic bridging bpp-alkynyl ligand L and alkynyl coordinated Pt(II) terpy units: [Fe(II)(L-Pt(II))2]2(BF4)2 (1). We identified two different types of crystals of 1 which differ in their molecular packing and the number of co-crystallized solvent molecules: 1H (1·3.5CH2Cl2 in P1[combining macron]) and 1L (1·10CH2Cl2 in C2/c); while 1L shows a reversible SCO with a transition temperature of 268 K, the analogous compound 1H does not show any SCO and remains blocked in the HS state. The temperature-dependent magnetic properties of 1H and 1L were complementarily studied by Mössbauer spectroscopy. It has been shown that 1L performs thermal spin <span class="hlt">crossover</span> and that 1L can be excited to a LIESST state. The vibrational properties of 1 were investigated by experimental nuclear resonance vibrational spectroscopy. The experimentally determined partial density of vibrational states (pDOS) was compared to a DFT-based simulation of the pDOS. The vibrational modes of the different components were assigned and visualized. In addition, the photophysical properties of 1 and L-Pt were investigated in the solid state and in solution. The ultrafast transient absorption spectroscopy of 1 in solution was carried out to study the PL quenching channel via energy transfer from photoexcited Pt(II) terpy units to the Fe(II)-moiety.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22390845','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22390845"><span>Design and numerical characterization of a <span class="hlt">crossover</span> EBIS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Geyer, Sabrina Langbein, A. Meusel, Oliver; Kester, Oliver</p> <p>2015-01-09</p> <p>For the investigation of highly charged ions, a <span class="hlt">crossover</span> EBIS (XEBIS) was developed at the University of Frankfurt. In contrast to conventional EBIS/T devices the compression of the electron beam is achieved by electrostatic focusing to a <span class="hlt">crossover</span> point in the interaction region. This concept allows a compact and simple design. Simulations performed with EGUN show a perveance of 2.1×10{sup −7} A/V{sup 3/2} for the realized gun system. In the interaction region the electron beam has a density of around 10 A/cm{sup 2} and a minimum radius of 0.15 mm. The XEBIS has a total length of 112 mm with a trap length of 26 mm. It is designed for electron beam energies of up to 6 keV/q. The storage capacity of the trap region is in the order of 1×10{sup 8} charges. Charge state breeding studies with CBSIM indicate for the noble gases as maximal achievable charge state Ar{sup 16+}, Kr{sup 30+} and Xe{sup 35+}. Thus ion beam currents of around 2.04 nA assuming 50 Hz repetition rate can be expected. The emittance of the extracted beam is approximated to 8 mm mrad. After completion of the construction phase, the XEBIS will be installed for first performance investigations at a dedicated test bench, equipped with a fast Faraday Cup (FC), a retarding field spectrometer, a luminescence screen and optical diagnostics. Subsequently the XEBIS will serve as source for highly charged ions at different experimental setups.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AIPC.1640..141G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AIPC.1640..141G"><span>Design and numerical characterization of a <span class="hlt">crossover</span> EBIS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Geyer, Sabrina; Langbein, A.; Meusel, Oliver; Kester, Oliver</p> <p>2015-01-01</p> <p>For the investigation of highly charged ions, a <span class="hlt">crossover</span> EBIS (XEBIS) was developed at the University of Frankfurt. In contrast to conventional EBIS/T devices the compression of the electron beam is achieved by electrostatic focusing to a <span class="hlt">crossover</span> point in the interaction region. This concept allows a compact and simple design. Simulations performed with EGUN show a perveance of 2.1×10-7 A/V3/2 for the realized gun system. In the interaction region the electron beam has a density of around 10 A/cm2 and a minimum radius of 0.15 mm. The XEBIS has a total length of 112 mm with a trap length of 26 mm. It is designed for electron beam energies of up to 6 keV/q. The storage capacity of the trap region is in the order of 1×108 charges. Charge state breeding studies with CBSIM indicate for the noble gases as maximal achievable charge state Ar16+, Kr30+ and Xe35+. Thus ion beam currents of around 2.04 nA assuming 50 Hz repetition rate can be expected. The emittance of the extracted beam is approximated to 8 mm mrad. After completion of the construction phase, the XEBIS will be installed for first performance investigations at a dedicated test bench, equipped with a fast Faraday Cup (FC), a retarding field spectrometer, a luminescence screen and optical diagnostics. Subsequently the XEBIS will serve as source for highly charged ions at different experimental setups.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20158035','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20158035"><span>The <span class="hlt">crossover</span> from single file to Fickian diffusion.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sané, Jimaan; Padding, Johan T; Louis, Ard A</p> <p>2010-01-01</p> <p>The <span class="hlt">crossover</span> from single-file diffusion, where the mean-square displacement scales as (x2) to approximately t(1/2), to normal Fickian diffusion, where (x2) to approximately t, is studied as a function of channel width for colloidal particles. By comparing Brownian dynamics to a hybrid molecular dynamics and mesoscopic simulation technique, we can study the effect of hydrodynamic interactions on the single file mobility and on the <span class="hlt">crossover</span> to Fickian diffusion for wider channel widths. For disc-like particles with a steep interparticle repulsion, the single file mobilities for different particle densities are well described by the exactly solvable hard-rod model. This holds both for simulations that include hydrodynamics, as well as for those that do not. When the single file constraint is lifted, then for particles of diameter sigma and pipe of width L such that (L - 2sigma)/sigma = deltac < 1, the particles can be described as hopping past one-another in an average time t(hop). For shorter times t < t(hop) the particles still exhibit sub-diffusive behaviour, but at longer times t > t(hop), normal Fickian diffusion sets in with an effective diffusion constant Dhop to approximately 1/ mean square root of t(hop). For the Brownian particles, t(hop) to approximately deltac(-2) when deltac < 1, but when hydrodynamic interactions are included, we find a stronger dependence than deltac(-2). We attribute this difference to short-range lubrication forces that make it more difficult for particles to hop past each other in very narrow channels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28356327','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28356327"><span>The <span class="hlt">crossover</span> conformational shift of the GTPase atlastin provides the energy driving ER fusion.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Winsor, James; Hackney, David D; Lee, Tina H</p> <p>2017-05-01</p> <p>The homotypic fusion of endoplasmic reticulum membranes is catalyzed by the atlastin GTPase. The mechanism involves trans-dimerization between GTPase heads and a favorable <span class="hlt">crossover</span> conformational shift, catalyzed by GTP hydrolysis, that converts the dimer from a "prefusion" to "postfusion" state. However, whether <span class="hlt">crossover</span> formation actually energizes fusion remains unclear, as do the sequence of events surrounding it. Here, we made mutations in atlastin to selectively destabilize the <span class="hlt">crossover</span> conformation and used fluorescence-based kinetic assays to analyze the variants. All variants underwent dimerization and <span class="hlt">crossover</span> concurrently, and at wild-type rates. However, certain variants were unstable once in the <span class="hlt">crossover</span> dimer conformation, and <span class="hlt">crossover</span> dimer stability closely paralleled lipid-mixing activity. Tethering, however, appeared to be unimpaired in all mutant variants. The results suggest that tethering and lipid mixing are catalyzed concurrently by GTP hydrolysis but that the energy requirement for lipid mixing exceeds that for tethering, and the full energy released through <span class="hlt">crossover</span> formation is necessary for fusion. © 2017 Winsor et al.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JPS...195.4622C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JPS...195.4622C"><span>Effect of gas composition on Ru dissolution and <span class="hlt">crossover</span> in polymer-electrolyte membrane fuel cells</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cheng, Tommy T. H.; Jia, Nengyou; Colbow, Vesna; Wessel, Silvia; Dutta, Monica</p> <p></p> <p>Pt-Ru-based anodes are commonly used in polymer-electrolyte membrane fuel cells (PEMFCs) to provide improved CO tolerance for reformate fuel applications. However, Ru <span class="hlt">crossover</span> from the anode to the cathode has been identified as a critical durability problem that has severe performance implications. In the present study, an anode accelerated stress test (AST) was used to simulate potential spikes that occur during fuel cell start-ups and shutdowns to induce Ru <span class="hlt">crossover</span>. The effects of fuel gas composition, namely hydrogen and carbon dioxide concentrations, on Ru dissolution and <span class="hlt">crossover</span> were investigated. The cell performance losses were correlated with the degree of Ru <span class="hlt">crossover</span> as determined by the changes in cathode cyclic voltammetry (CV) characteristics and neutron activation analysis (NAA). It was found that higher hydrogen concentration in the fuel accelerated Ru <span class="hlt">crossover</span> and that the presence of carbon dioxide hindered Ru <span class="hlt">crossover</span>. In particular, the injection of 20 vol.% carbon dioxide during potential cycling resulted in very minor Ru <span class="hlt">crossover</span>, which showed essentially identical performance losses and CV characteristic changes as a fuel cell composed of a Ru-free anode. The experimental results suggest that the Ru species in our Pt-Ru metal oxide catalysts need to go through a reduction step by hydrogen before dissolution. The presence of carbon dioxide may play a role in hindering the reduction step.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2929096','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2929096"><span><span class="hlt">Crossovers</span> Get a Boost in Brassica Allotriploid and Allotetraploid Hybrids[W</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Leflon, Martine; Grandont, Laurie; Eber, Frédérique; Huteau, Virginie; Coriton, Olivier; Chelysheva, Liudmila; Jenczewski, Eric; Chèvre, Anne-Marie</p> <p>2010-01-01</p> <p>Meiotic <span class="hlt">crossovers</span> are necessary to generate balanced gametes and to increase genetic diversity. Even if <span class="hlt">crossover</span> number is usually constrained, recent results suggest that manipulating karyotype composition could be a new way to increase <span class="hlt">crossover</span> frequency in plants. In this study, we explored this hypothesis by analyzing the extent of <span class="hlt">crossover</span> variation in a set of related diploid AA, allotriploid AAC, and allotetraploid AACC Brassica hybrids. We first used cytogenetic methods to describe the meiotic behavior of the different hybrids. We then combined a cytogenetic estimation of class I <span class="hlt">crossovers</span> in the entire genome by immunolocalization of a key protein, MutL Homolog1, which forms distinct foci on meiotic chromosomes, with genetic analyses to specifically compare <span class="hlt">crossover</span> rates between one pair of chromosomes in the different hybrids. Our results showed that the number of <span class="hlt">crossovers</span> in the allotriploid AAC hybrid was higher than in the diploid AA hybrid. Accordingly, the allotetraploid AACC hybrid showed an intermediate behavior. We demonstrated that this increase was related to hybrid karyotype composition (diploid versus allotriploid versus allotetraploid) and that interference was maintained in the AAC hybrids. These results could provide another efficient way to manipulate recombination in traditional breeding and genetic studies. PMID:20622148</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26660866','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26660866"><span>TD-DFT study of the light-induced spin <span class="hlt">crossover</span> of Fe(III) complexes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Saureu, Sergi; de Graaf, Coen</p> <p>2016-01-14</p> <p>Two light-induced spin-<span class="hlt">crossover</span> Fe(III) compounds have been studied with time-dependent density functional theory (TD-DFT) to investigate the deactivation mechanism and the role of the ligand-field states as intermediates in this process. The B3LYP* functional has previously shown its ability to accurately describe (light-induced) spin-<span class="hlt">crossover</span> in Fe(II) complexes. Here, we establish its performance for Fe(III) systems using [Fe(qsal)2](+) (Hqsal = 2-[(8-quinolinylimino)methyl]phenol) and [Fe(pap)2](+) (Hpap = 2-(2-pyridylmethyleneamino)phenol) as test cases comparing the B3LYP* results to experimental information and to multiconfigurational wave function results. In addition to rather accurate high spin (HS) and low spin (LS) state geometries, B3LYP* also predicts ligand-to-metal charge transfer (LMCT) states with large oscillator strength in the energy range where the UV-VIS spectrum shows an intense absorption band, whereas optically allowed π-π* excitations on the ligands were calculated at higher energy. Subsequently, we have generated a two-dimensional potential energy surface of the HS and LS states varying the Fe-N and Fe-O distances. LMCT and metal centered (MC) excited states were followed along the approximate minimal energy path that connects the minima of the HS and LS on this surface. The (2)LMCT state has a minimum in the same region as the initial LS state, where we also observe a crossing with the intermediate spin (IS) state. Upon the expansion of the coordination sphere of the Fe(III) ion, the IS state crosses with the HS state and further expansion of the coordination sphere leads to the excited spin state trapping as observed in <span class="hlt">experiment</span>. The calculation of the intersystem crossing rates reveals that the deactivation from (2)LMCT → IS → HS competes with the (2)LMCT → IS → LS pathway, in line with the low efficiency encountered in <span class="hlt">experiments</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4963421','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4963421"><span>A Pilot Study on Culottes versus <span class="hlt">Crossover</span> Single Stenting for True Coronary Bifurcation Lesions</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhang, Linlin; Zhong, Wenliang; Luo, Yukun; Chen, Lianglong</p> <p>2016-01-01</p> <p>Background The purpose of our study was to compare clinical and angiographic outcomes of planned culottes technique with that of provisional <span class="hlt">crossover</span> single stenting in the treatment of true coronary bifurcation lesions (CBL) with drug-eluting stent (DES). Methods True CBL patients (n = 104) were randomly assigned to either the provisional stenting of the side branch (<span class="hlt">crossover</span> group) or the culottes group. Additional side branch (SB) stenting in the <span class="hlt">crossover</span> group was required if there was thrombolysis in myocardial infarction flow ≤ 1 flow). The primary end point was the occurrence of major adverse cardiac events (MACE) at nine months, including cardiac death, myocardial infarction, target lesion/vessel revascularization and in-stent thrombosis. The secondary end point was angiographic in-segment restenosis at nine months. Results The rate of MACE at nine months was similar between the <span class="hlt">crossover</span> and culottes groups (7.7% vs. 7.7%, p = 1.000). Additional SB stenting in the <span class="hlt">crossover</span> group was required in 3.8% of patients. There was one procedural occlusion of SB in the <span class="hlt">crossover</span> group. At nine months, the rate of in-segment restenosis was similar in the parent main vessel (0% vs. 1.9%, p = 1.000), main branch (1.9% vs. 7.7%, p = 0.363) and SB (17.3% vs. 9.6%, p = 0.250) between the <span class="hlt">crossover</span> and culottes groups, respectively. Conclusions This study demonstrated that there is no significant difference in cumulative MACE or in-segment restenosis between <span class="hlt">crossover</span> and culottes groups. Larger randomized clinical trials are warranted to re-evaluate the outcomes of the provisional <span class="hlt">crossover</span> stenting versus the culottes stenting techniques utilizing DES for true CBL. PMID:27471358</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21161249','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21161249"><span><span class="hlt">Crossover</span> replantation as a salvage procedure following bilateral transhumeral upper limb amputation: a case report.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ozçelik, Ismail Bülent; Mersa, Berkan; Kabakaş, Fatih; Saçak, Bülent; Kuvat, Samet Vasfi</p> <p>2011-04-01</p> <p><span class="hlt">Cross-over</span> replantation is a salvage option for cases with bilateral extremity amputations where the wound conditions do not enable an orthotopic replantation. Here, we present a 24-year-old patient who applied to our center with bilateral transhumeral amputations. Due to the wound conditions, a <span class="hlt">cross-over</span> replantation was performed. 24 months after the initial operation, the patient exhibits good protective sensation at the distal levels and function to some degree, whereas the active range of motion is not as promising as previously expected. In this article, we present this case together with its immediate and long-term outcomes and the consequences of the <span class="hlt">cross-over</span> replantation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23786490','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23786490"><span><span class="hlt">Crossover</span> versus parallel designs: dose-escalation design comparisons for first-in-human studies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yan, Zhiwu; Hosmane, Balakrishna; Locke, Charles</p> <p>2013-01-01</p> <p>We study the statistical efficiency for rising-dose designs in the context of first-in-human studies. Specifically, we identify a class of <span class="hlt">crossover</span> designs that are appealing in terms of both subject safety and statistical efficiency and, for a three-period, two-panel design in such a class, we compare its A-efficiency relative to the corresponding parallel designs and optimal/efficient <span class="hlt">crossover</span> designs, respectively, under various plausible models. In the meantime, we also evaluate the impact of inclusion of baseline measurements as a covariate in the statistical analysis, for both <span class="hlt">crossover</span> and parallel studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20503990','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20503990"><span>Tuning size and thermal hysteresis in bistable spin <span class="hlt">crossover</span> nanoparticles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Galán-Mascarós, José Ramón; Coronado, Eugenio; Forment-Aliaga, Alicia; Monrabal-Capilla, María; Pinilla-Cienfuegos, Elena; Ceolin, Marcelo</p> <p>2010-06-21</p> <p>Nanoparticles of iron(II) triazole salts have been prepared from water-organic microemulsions. The mean size of the nanoparticles can be tuned down to 6 nm in diameter, with a narrow size distribution. A sharp spin transition from the low spin (LS) to the high spin (HS) state is observed above room temperature, with a 30-40-K-wide thermal hysteresis. The same preparation can yield second generation nanoparticles containing molecular alloys by mixing triazole with triazole derivatives, or from metallic mixtures of iron(II) and zinc(II). In these nanoparticles of 10-15 nm, the spin transition "moves" towards lower temperatures, reaching a 316 K limit for the cooling down transition and maintaining a thermal hysteresis over 15-20-K-wide. The nanoparticles were characterized by dynamic light scattering, TEM, and AFM, after deposition on gold or silicon surfaces. The spin transition was characterized by magnetic susceptibility measurements and EXAFS (in solid samples after solvent removal) and also by the color change between the LS (violet) and HS (colorless) states in an organic solvent suspension. The discovery of bistable magnetic nanoparticles of 6 nm with a wide thermal hysteresis above room temperature showcases the actual possibilities of spin <span class="hlt">crossover</span> materials for nanotechnological applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4483742','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4483742"><span>Flooding and Clostridium difficile Infection: A Case-<span class="hlt">Crossover</span> Analysis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lin, Cynthia J.; Wade, Timothy J.; Hilborn, Elizabeth D.</p> <p>2015-01-01</p> <p>Clostridium difficile is a bacterium that can spread by water. It often causes acute gastrointestinal illness in older adults who are hospitalized and/or receiving antibiotics; however, community-associated infections affecting otherwise healthy individuals have become more commonly reported. A case-<span class="hlt">crossover</span> study was used to assess emergency room (ER) and outpatient visits for C. difficile infection following flood events in Massachusetts from 2003 through 2007. Exposure status was based on whether or not a flood occurred prior to the case/control date during the following risk periods: 0–6 days, 7–13 days, 14–20 days, and 21–27 days. Fixed-effects logistic regression was used to estimate the risk of diagnosis with C. difficile infection following a flood. There were 129 flood events and 1575 diagnoses of C. difficile infection. Among working age adults (19–64 years), ER and outpatient visits for C. difficile infection were elevated during the 7–13 days following a flood (Odds Ratio, OR = 1.69; 95% Confidence Interval, CI: 0.84, 3.37). This association was more substantial among males (OR = 3.21; 95% CI: 1.01–10.19). Associations during other risk periods were not observed (p < 0.05). Although we were unable to differentiate community-associated versus nosocomial infections, a potential increase in C. difficile infections should be considered as more flooding is projected due to climate change. PMID:26090609</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26174461','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26174461"><span>A randomized <span class="hlt">crossover</span> clinical trial of sertraline for intradialytic hypotension.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Razeghi, Effat; Dashti-Khavidaki, Simin; Nassiri, Samira; Abolghassemi, Rozita; Khalili, Hossein; Hashemi Nazari, Seyed Saeed; Mansournia, Mohammad Ali; Taraz, Mohammad</p> <p>2015-07-01</p> <p>Intradialytic hypotension (IDH) has been reported in 15% to 50% of hemodialysis patients and increases patients morbidity and mortality. Some small noncontrolled studies evaluated the effect of sertraline on IDH with conflicting results. This study is a randomized <span class="hlt">crossover</span> controlled trial on the effectiveness of sertraline to reduce IDH. Patients on hemodialysis who suffered IDH in at least 50% of their dialysis sessions were enrolled. Each patient received either sertraline or placebo for 4 weeks and after a 4-week washout period, was switched to the other arm of the trial. All patients started sertraline at a daily dose of 50 mg that increased to 100 mg after 1 week. Twelve patients completed all phases of the study. Sertraline therapy increased nadir intradialysis diastolic and systolic blood pressure by 3.8 mm Hg and 4.9 mm Hg at the end of the intervention, respectively. Sertraline therapy also significantly increased postdialysis diastolic and systolic blood pressure by 6.0 mm Hg and 8.7 mm Hg. Sertraline therapy significantly reduced the risk of hypotension episodes by 43%. The improvement of intradialysis and postdialysis diastolic and systolic blood pressure were only significant in nondiabetic patients. Sertraline therapy significantly increases intradialysis and postdialysis blood pressure. These effects of sertraline can result in significant decrease in hypotension episodes during dialysis treatment and the number of interventions required to manage IDH. However, not all patients may benefit from sertraline depending on comorbidities such as diabetes mellitus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JChPh.145v4702K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JChPh.145v4702K"><span>Thermopower of molecular junctions: Tunneling to hopping <span class="hlt">crossover</span> in DNA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Korol, Roman; Kilgour, Michael; Segal, Dvira</p> <p>2016-12-01</p> <p>We study the electrical conductance G and the thermopower S of single-molecule junctions and reveal signatures of different transport mechanisms: off-resonant tunneling, on-resonant coherent (ballistic) motion, and multi-step hopping. These mechanisms are identified by studying the behavior of G and S while varying molecular length and temperature. Based on a simple one-dimensional model for molecular junctions, we derive approximate expressions for the thermopower in these different regimes. Analytical results are compared to numerical simulations, performed using a variant of Büttiker's probe technique, the so-called voltage-temperature probe, which allows us to phenomenologically introduce environmentally induced elastic and inelastic electron scattering effects, while applying both voltage and temperature biases across the junction. We further simulate the thermopower of GC-rich DNA sequences with mediating A:T blocks and manifest the tunneling-to-hopping <span class="hlt">crossover</span> in both the electrical conductance and the thermopower, in accord with measurements by Li et al. [Nat. Commun. 7, 11294 (2016)].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1258609-quantum-classical-crossover-near-quantum-critical-point','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1258609-quantum-classical-crossover-near-quantum-critical-point"><span>Quantum-to-classical <span class="hlt">crossover</span> near quantum critical point</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Vasin, M.; Ryzhov, V.; Vinokur, V. M.</p> <p>2015-12-21</p> <p>A quantum phase transition (QPT) is an inherently dynamic phenomenon. However, while non-dissipative quantum dynamics is described in detail, the question, that is not thoroughly understood is how the omnipresent dissipative processes enter the critical dynamics near a quantum critical point (QCP). Here we report a general approach enabling inclusion of both adiabatic and dissipative processes into the critical dynamics on the same footing. We reveal three distinct critical modes, the adiabatic quantum mode (AQM), the dissipative classical mode [classical critical dynamics mode (CCDM)], and the dissipative quantum critical mode (DQCM). We find that as a result of the transitionmore » from the regime dominated by thermal fluctuations to that governed by the quantum ones, the system acquires effective dimension d+zΛ(T), where z is the dynamical exponent, and temperature-depending parameter Λ(T)ε[0, 1] decreases with the temperature such that Λ(T=0) = 1 and Λ(T →∞) = 0. Lastly, our findings lead to a unified picture of quantum critical phenomena including both dissipation- and dissipationless quantum dynamic effects and offer a quantitative description of the quantum-to-classical <span class="hlt">crossover</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16532455','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16532455"><span>Blinded placebo <span class="hlt">crossover</span> study of gabapentin in primary orthostatic tremor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rodrigues, Julian P; Edwards, Dylan J; Walters, Susan E; Byrnes, Michelle L; Thickbroom, Gary W; Stell, Rick; Mastaglia, Frank L</p> <p>2006-07-01</p> <p>Primary orthostatic tremor (OT) is a rare but disabling condition characterized by leg tremor and feelings of instability during stance. Previous studies have reported a reduction in OT symptoms with gabapentin treatment. In this study, we report on the benefits of gabapentin treatment in a double-blind placebo-controlled <span class="hlt">crossover</span> study of 6 OT patients. First, the maximally effective gabapentin dosage (600-2,700 mg/day) for each patient was determined during an initial dose-titration phase. Patients were then studied 7 days after drug withdrawal and again after two 2-week periods of treatment with either gabapentin or placebo, using force platform posturography to quantify postural sway and tremor. Other medications for OT were continued unchanged. Symptomatic response was assessed by a patient-rated severity scale and quality of life (QOL) questionnaire. All patients reported an increase in symptoms during the washout phase and symptom reduction (50%-75%) during gabapentin treatment. Tremor amplitude was reduced to 79% +/- 11% and sway area to 71% +/- 11% of the placebo state. QOL improved in all patients, no adverse drug effects were noted, and symptomatic benefit was maintained at follow-up (mean = 19 months). The findings confirm that gabapentin is an effective treatment for OT, reducing both tremor and postural instability and improving quality of life, and support its use as add-on or first-line therapy for OT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21408468','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21408468"><span>BCS-BEC <span class="hlt">crossover</span> with unequal-mass fermions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Diener, Roberto B.; Randeria, Mohit</p> <p>2010-03-15</p> <p>We investigate the <span class="hlt">crossover</span> from BCS pairing to molecular Bose-Einstein condensation (BEC) in an atomic gas with two fermion species with masses m{sub {up_arrow}{ne}m{down_arrow}}tuned through a Feshbach resonance. We present results for the T=0 equation of state as a function of the scattering length including the effects of Gaussian fluctuations about the mean field ground state. We compute the ground state energy as a function of m{sub {up_arrow}/}m{sub {down_arrow}}at unitarity and find excellent agreement with the quantum Monte Carlo result for m{sub {up_arrow}/}m{sub {down_arrow}=}6.67 for a {sup 40}K-{sup 6}Li mixture. We show that the dimer scattering length in the BEC limit as a function of m{sub {up_arrow}/}m{sub {down_arrow}}compares well with the exact four-body results of Petrov et al. [J. Phys. B 38, S645 (2005)]. We also derive the condition for trapping frequencies to obtain an unpolarized gas in a harmonic trap.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhRvE..89a2105S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhRvE..89a2105S"><span>Finite size induces <span class="hlt">crossover</span> temperature in growing spin chains</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sienkiewicz, Julian; Suchecki, Krzysztof; Hołyst, Janusz A.</p> <p>2014-01-01</p> <p>We introduce a growing one-dimensional quenched spin model that bases on asymmetrical one-side Ising interactions in the presence of external field. Numerical simulations and analytical calculations based on Markov chain theory show that when the external field is smaller than the exchange coupling constant J there is a nonmonotonous dependence of the mean magnetization on the temperature in a finite system. The <span class="hlt">crossover</span> temperature Tc corresponding to the maximal magnetization decays with system size, approximately as the inverse of the Lambert W function. The observed phenomenon can be understood as an interplay between the thermal fluctuations and the presence of the first cluster determined by initial conditions. The effect exists also when spins are not quenched but fully thermalized after the attachment to the chain. By performing tests on real data we conceive the model is in part suitable for a qualitative description of online emotional discussions arranged in a chronological order, where a spin in every node conveys emotional valence of a subsequent post.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3296130','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3296130"><span>Control in the Middle (CIM) for Three Period <span class="hlt">Crossover</span> Studies</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shuster, Jonathan; Anton, Stephen D.; Theriaque, Douglas; Yoon, Saunjoo</p> <p>2012-01-01</p> <p>Three period <span class="hlt">crossover</span> studies can be efficient and convenient methods of conducting Phase II clinical trials. Non-randomly placing control in the middle (CIM) has not been practiced, but may be extremely useful in studies testing herbal products for which placebos are not available, or for distinguishing between behavioral and biological effects. Furthermore, this design can serve as a valuable addition to classical studies of either (a) two competing treatments or (b) treatment versus placebo versus an open label “nothing” as the control. Therefore, we propose rigorous designs that will help practitioners efficiently answer research questions where (1) two active treatments need to be compared against each other with treatment vs. placebo comparisons of secondary importance; (2) a single active treatment needs to be tested where no placebo is available; or (3) the placebo effect is of interest in a treatment vs. placebo trial. For studies where no placebo is available, deception will be required, with participants told that in one randomly selected period (#1 or #3) they will receive the active treatment, and that they will receive a new experimental inert placebo in the other period. Assuming this design is approved by an ethics committee, it can be very useful in biomedical research. PMID:21509714</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080007395','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080007395"><span>At grade optical <span class="hlt">crossover</span> for monolithic optial circuits</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jamieson, Robert S. (Inventor)</p> <p>1983-01-01</p> <p>Planar optical circuits may be made to cross through each other, (thus eliminating extra steps required to fabricate elevated, nonintersecting <span class="hlt">crossovers</span>) by control of the dimensions of the crossing light conductors (10, 12) to be significantly greater than d=0.89.lambda. and the angle of crossing as nearly 90.degree. as conveniently possible. A light trap may be provided just ahead of the intersection to trap any light being reflected in the source conductor at angles greater than about 45.degree.. The light trap may take the form of triangular shaped portions (16a, 16b) on each side of the source conductor with the far side of the triangular portion receiving incident light at an angle so that incident light will be reflected to the other side, or it may take the form of windows (18a, 18b) in place of the triangular portions. Planar optical circuit boards (21-23) may be fabricated and stacked to form a keyboard (20) with intersecting conductors (26-29) and keyholes (0-9) where conductors merge at the broad side of the circuit boards. These keyholes may be prearranged to form an array or matrix of keyholes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22569882','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22569882"><span>The dynamic <span class="hlt">crossover</span> in water does not require bulk water.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Turton, David A; Corsaro, Carmelo; Martin, David F; Mallamace, Francesco; Wynne, Klaas</p> <p>2012-06-14</p> <p>Many of the anomalous properties of water may be explained by invoking a second critical point that terminates the coexistence line between the low- and high-density amorphous states in the liquid. Direct experimental evidence of this point, and the associated polyamorphic liquid-liquid transition, is elusive as it is necessary for liquid water to be cooled below its homogeneous-nucleation temperature. To avoid crystallization, water in the eutectic LiCl solution has been studied but then it is generally considered that "bulk" water cannot be present. However, recent computational and experimental studies observe cooperative hydration in which case it is possible that sufficient hydrogen-bonded water is present for the essential characteristics of water to be preserved. For femtosecond optical Kerr-effect and nuclear magnetic resonance measurements, we observe in each case a fractional Stokes-Einstein relation with evidence of the dynamic <span class="hlt">crossover</span> appearing near 220 K and 250 K respectively. Spectra obtained in the glass state also confirm the complex nature of the hydrogen-bonding modes reported for neat room-temperature water and support predictions of anomalous diffusion due to "worm-hole" structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24580170','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24580170"><span>Finite size induces <span class="hlt">crossover</span> temperature in growing spin chains.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sienkiewicz, Julian; Suchecki, Krzysztof; Hołyst, Janusz A</p> <p>2014-01-01</p> <p>We introduce a growing one-dimensional quenched spin model that bases on asymmetrical one-side Ising interactions in the presence of external field. Numerical simulations and analytical calculations based on Markov chain theory show that when the external field is smaller than the exchange coupling constant J there is a nonmonotonous dependence of the mean magnetization on the temperature in a finite system. The <span class="hlt">crossover</span> temperature Tc corresponding to the maximal magnetization decays with system size, approximately as the inverse of the Lambert W function. The observed phenomenon can be understood as an interplay between the thermal fluctuations and the presence of the first cluster determined by initial conditions. The effect exists also when spins are not quenched but fully thermalized after the attachment to the chain. By performing tests on real data we conceive the model is in part suitable for a qualitative description of online emotional discussions arranged in a chronological order, where a spin in every node conveys emotional valence of a subsequent post.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4685645','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4685645"><span>Quantum-to-classical <span class="hlt">crossover</span> near quantum critical point</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vasin, M.; Ryzhov, V.; Vinokur, V. M.</p> <p>2015-01-01</p> <p>A quantum phase transition (QPT) is an inherently dynamic phenomenon. However, while non-dissipative quantum dynamics is described in detail, the question, that is not thoroughly understood is how the omnipresent dissipative processes enter the critical dynamics near a quantum critical point (QCP). Here we report a general approach enabling inclusion of both adiabatic and dissipative processes into the critical dynamics on the same footing. We reveal three distinct critical modes, the adiabatic quantum mode (AQM), the dissipative classical mode [classical critical dynamics mode (CCDM)], and the dissipative quantum critical mode (DQCM). We find that as a result of the transition from the regime dominated by thermal fluctuations to that governed by the quantum ones, the system acquires effective dimension d + zΛ(T), where z is the dynamical exponent, and temperature-depending parameter Λ(T) ∈ [0, 1] decreases with the temperature such that Λ(T = 0) = 1 and Λ(T → ∞) = 0. Our findings lead to a unified picture of quantum critical phenomena including both dissipation- and dissipationless quantum dynamic effects and offer a quantitative description of the quantum-to-classical <span class="hlt">crossover</span>. PMID:26688102</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3571647','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3571647"><span>Does Milk Cause Constipation? A <span class="hlt">Crossover</span> Dietary Trial</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Crowley, Elesa T.; Williams, Lauren T.; Roberts, Tim K.; Dunstan, Richard H.; Jones, Peter D.</p> <p>2013-01-01</p> <p>The aims of this study were to: (1) determine whether replacement of cow’s milk protein with soy resolves Chronic Functional Constipation (CFC); and (2) investigate the effects of cow’s milk β casein A1 and cow’s milk β casein A2 on CFC. Children diagnosed with CFC were recruited to one of two <span class="hlt">crossover</span> trials: Trial 1 compared the effects of cow’s milk and soy milk; Trial 2 compared the effects of cow’s milk β casein A1 and cow’s milk β casein A2. Resolution of constipation was defined as greater than eight bowel motions during a two week intervention. Thirteen children (18 to 144 months) participated in Trial 1 (6 boys, 7 girls). Nine participants who completed the soy epoch all experienced resolution (p < 0.05). Thirty-nine children (21 to 144 months) participated in Trial 2 (25 boys, 14 girls). Resolution of constipation was highest during the washout epoch, 81%; followed by cow’s milk β casein A2, 79%; and cow’s milk β casein A1, 57%; however, the proportions did not differ statistically. The results of Trial 1 demonstrate an association between CFC and cow’s milk consumption but Trial 2 failed to show an effect from type of casein. Some other component in cow’s milk common to both A1 and A2 milk may be causing a problem in these susceptible children. PMID:23340316</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870055081&hterms=Qualitative+data+analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DQualitative%2Bdata%2Banalysis','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870055081&hterms=Qualitative+data+analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DQualitative%2Bdata%2Banalysis"><span>Analysis of <span class="hlt">crossover</span> between local and massive separation on airfoils</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barnett, Mark</p> <p>1987-01-01</p> <p>The occurrence of massive separation on airfoils operating at high Reynolds number poses an important problem to the aerodynamicist. In the present study, the phenomenon of <span class="hlt">crossover</span>, induced by airfoil thickness, between local separation and massive separation is investigated for low speed (incompressible), symmetric flow past realistic airfoil geometries. This problem is studied both for the infinite Reynolds number asymptotic limit using triple-deck theory and for finite Reynolds number using interacting boundary-layer theory. Numerical results are presented which illustrate how the flow evolves from local to massive separation as the airfoil thickness is increased. The results of the triple-deck and the interacting boundary-layer analyses are found to be in qualitative agreement for the NACA four digit series and an uncambered supercritical airfoil. The effect of turbulence on the evolution of the flow is also considered. Solutions are presented for turbulent flows past a NACA 0014 airfoil and a circular cylinder. For the latter case, the calculated surface pressure distribution is found to agree well with experimental data if the proper eddy pressure level is specified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28690996','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28690996"><span>Long Term Outcomes of Femorofemoral <span class="hlt">Crossover</span> Bypass Grafts.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Park, Keun-Myoung; Park, Yang-Jin; Kim, Young-Wook; Hyun, Dongho; Park, Kwang Bo; Do, Young-Soo; Kim, Dong-Ik</p> <p>2017-06-01</p> <p>Femorofemoral <span class="hlt">crossover</span> bypass (FCB) is a good procedure for patients with unilateral iliac artery disease. There are many articles about the results of FCB, but most of them were limited to 5 years follow-up. The purpose of our study was to analysis the results of FCB with a 10-year follow-up period. Between January 1995 and December 2010, 133 patients were operated in Samsung Medical Center (median follow-up: 58.8 months). We retrospectively analysed patient characteristics, the preoperative treatment, the operative procedure, and material used. The indications for FCB were claudication in 110 and critical limb ischemia in 23 patients. Three patients were died due to myocardiac infarction, intracranial hemorrhage, and acute respiratory failure within 30 days after surgery. The one-year primary and secondary patency rates were 89% and 97%, the 5-year primary and secondary patency rates were 70% and 85%, and the 10-year primary and secondary patency rates were 31% and 67%. The 5-year and 10-year limb salvage rates were 97% and 95%, respectively. Our long term analysis suggests that FCB might be a valuable alternative treatment modality in patients with unilateral iliac artery disease.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17710740','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17710740"><span>Sequential design approaches for bioequivalence studies with <span class="hlt">crossover</span> designs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Potvin, Diane; DiLiberti, Charles E; Hauck, Walter W; Parr, Alan F; Schuirmann, Donald J; Smith, Robert A</p> <p>2008-01-01</p> <p>The planning of bioequivalence (BE) studies, as for any clinical trial, requires a priori specification of an effect size for the determination of power and an assumption about the variance. The specified effect size may be overly optimistic, leading to an underpowered study. The assumed variance can be either too small or too large, leading, respectively, to studies that are underpowered or overly large. There has been much work in the clinical trials field on various types of sequential designs that include sample size reestimation after the trial is started, but these have seen only little use in BE studies. The purpose of this work was to validate at least one such method for <span class="hlt">crossover</span> design BE studies. Specifically, we considered sample size reestimation for a two-stage trial based on the variance estimated from the first stage. We identified two methods based on Pocock's method for group sequential trials that met our requirement for at most negligible increase in type I error rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017IJQI...1550027W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017IJQI...1550027W"><span>Quantum speed-up dynamical <span class="hlt">crossover</span> in open systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, W.-J.; Yan, K.; Xie, Y.-Q.; Wu, Yinzhong; Hao, Xiang</p> <p></p> <p>We put forward a measure for evaluating quantum speed limit for arbitrary mixed states of open systems by means of trace distance. Compared with some present measures, it can provide an optimal bound to the speed of the evolution. The dynamical <span class="hlt">crossover</span> from no speedup region to speedup region happens during the spontaneous decay of an atom. The evolution is characteristic of the alternating behavior between quantum acceleration and deceleration in the strong coupling case. Under the condition of detuning, the evolution can be initially accelerated and then decelerated to a normal process either in the weak or strong coupling regime. In accordance with the uncertainty relation, we demonstrate that the potential capacity for quantum speedup evolution is closely related to the energy feedback from the reservoir to the system. The negative decay rate for the evolution results in the speedup process where the photons previously emitted by the atom are reabsorbed at a later time. The values of the spontaneous decay rate become positive after a long enough time, which results in the evolution with no speedup potential.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27974736','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27974736"><span>Hed1 Promotes Meiotic <span class="hlt">Crossover</span> Formation in Saccharomyces cerevisiae.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kong, Yoon-Ju; Joo, Jeong-Hwan; Kim, Keun Pil; Hong, Soogil</p> <p>2017-02-28</p> <p>Homologous recombination occurs between homologous chromosomes and is significantly involved in programmed double-strand break (DSB) repair. Activation of two recombinases, Rad51 and Dmc1, is essential for an interhomolog bias during meiosis. Rad51 participates in both mitotic and meiotic recombination, and its strand exchange activity is regulated by an inhibitory factor during meiosis. Thus, activities of Rad51 and Dmc1 are coordinated to promote homolog bias. It has been reported that Hed1, a meiosis-specific protein in budding yeast, regulates Rad51-dependent recombination activity. Here, we investigated the role of Hed1 in meiotic recombination by ectopic expression of the protein after pre-meiotic replication in Saccharomyces cerevisiae. DNA physical analysis revealed that the overexpression of Hed1 delays the DSB-to-joint molecule (JM) transition and promotes interhomolog JM formation. The study indicates a possible role of Hed1 in controlling the strand exchange activity of Rad51 and, eventually, meiotic <span class="hlt">crossover</span> formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26688102','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26688102"><span>Quantum-to-classical <span class="hlt">crossover</span> near quantum critical point.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vasin, M; Ryzhov, V; Vinokur, V M</p> <p>2015-12-21</p> <p>A quantum phase transition (QPT) is an inherently dynamic phenomenon. However, while non-dissipative quantum dynamics is described in detail, the question, that is not thoroughly understood is how the omnipresent dissipative processes enter the critical dynamics near a quantum critical point (QCP). Here we report a general approach enabling inclusion of both adiabatic and dissipative processes into the critical dynamics on the same footing. We reveal three distinct critical modes, the adiabatic quantum mode (AQM), the dissipative classical mode [classical critical dynamics mode (CCDM)], and the dissipative quantum critical mode (DQCM). We find that as a result of the transition from the regime dominated by thermal fluctuations to that governed by the quantum ones, the system acquires effective dimension d + zΛ(T), where z is the dynamical exponent, and temperature-depending parameter Λ(T) ∈ [0, 1] decreases with the temperature such that Λ(T = 0) = 1 and Λ(T → ∞) = 0. Our findings lead to a unified picture of quantum critical phenomena including both dissipation- and dissipationless quantum dynamic effects and offer a quantitative description of the quantum-to-classical <span class="hlt">crossover</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1258609','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1258609"><span>Quantum-to-classical <span class="hlt">crossover</span> near quantum critical point</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vasin, M.; Ryzhov, V.; Vinokur, V. M.</p> <p>2015-12-21</p> <p>A quantum phase transition (QPT) is an inherently dynamic phenomenon. However, while non-dissipative quantum dynamics is described in detail, the question, that is not thoroughly understood is how the omnipresent dissipative processes enter the critical dynamics near a quantum critical point (QCP). Here we report a general approach enabling inclusion of both adiabatic and dissipative processes into the critical dynamics on the same footing. We reveal three distinct critical modes, the adiabatic quantum mode (AQM), the dissipative classical mode [classical critical dynamics mode (CCDM)], and the dissipative quantum critical mode (DQCM). We find that as a result of the transition from the regime dominated by thermal fluctuations to that governed by the quantum ones, the system acquires effective dimension d+zΛ(T), where z is the dynamical exponent, and temperature-depending parameter Λ(T)ε[0, 1] decreases with the temperature such that Λ(T=0) = 1 and Λ(T →∞) = 0. Lastly, our findings lead to a unified picture of quantum critical phenomena including both dissipation- and dissipationless quantum dynamic effects and offer a quantitative description of the quantum-to-classical <span class="hlt">crossover</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23340316','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23340316"><span>Does milk cause constipation? A <span class="hlt">crossover</span> dietary trial.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Crowley, Elesa T; Williams, Lauren T; Roberts, Tim K; Dunstan, Richard H; Jones, Peter D</p> <p>2013-01-22</p> <p>The aims of this study were to: (1) determine whether replacement of cow's milk protein with soy resolves Chronic Functional Constipation (CFC); and (2) investigate the effects of cow's milk β casein A1 and cow's milk β casein A2 on CFC. Children diagnosed with CFC were recruited to one of two <span class="hlt">crossover</span> trials: Trial 1 compared the effects of cow's milk and soy milk; Trial 2 compared the effects of cow's milk β casein A1 and cow's milk β casein A2. Resolution of constipation was defined as greater than eight bowel motions during a two week intervention. Thirteen children (18 to 144 months) participated in Trial 1 (6 boys, 7 girls). Nine participants who completed the soy epoch all experienced resolution (p < 0.05). Thirty-nine children (21 to 144 months) participated in Trial 2 (25 boys, 14 girls). Resolution of constipation was highest during the washout epoch, 81%; followed by cow's milk β casein A2, 79%; and cow's milk β casein A1, 57%; however, the proportions did not differ statistically. The results of Trial 1 demonstrate an association between CFC and cow's milk consumption but Trial 2 failed to show an effect from type of casein. Some other component in cow's milk common to both A1 and A2 milk may be causing a problem in these susceptible children.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JLTP..tmp..264T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JLTP..tmp..264T"><span>Zero-Temperature Properties of a Strongly Interacting Superfluid Fermi Gas in the BCS-BEC <span class="hlt">Crossover</span> Region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tajima, H.; van Wyk, P.; Hanai, R.; Kagamihara, D.; Inotani, D.; Horikoshi, M.; Ohashi, Y.</p> <p>2016-11-01</p> <p>We investigate thermodynamic properties and effects of quantum fluctuations in the Bardeen-Cooper-Schrieffer (BCS)-Bose-Einstein condensation (BEC) <span class="hlt">crossover</span> region of a superfluid Fermi gas in the low-temperature limit. Including strong-coupling corrections within the framework of an extended T-matrix approximation, we numerically compute the isothermal compressibility χ _n . While quantum fluctuation effects on χ _n in the strong-coupling BEC regime are explained by the quantum depletion due to a repulsive interaction between tightly bound molecules, effects of self-energy shift on the Fermi chemical potential are found to enhance χ _n in the weak-coupling BCS region. We also show that the calculated χ _n agrees well with the recent <span class="hlt">experiment</span> on a ^6 Li Fermi gas done from the weak-coupling region to the unitarity limit. Our result would be useful for the study of many-body quantum corrections in the BCS-BEC <span class="hlt">crossover</span> region of a strongly interacting Fermi superfluid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JLTP..187..677T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JLTP..187..677T"><span>Zero-Temperature Properties of a Strongly Interacting Superfluid Fermi Gas in the BCS-BEC <span class="hlt">Crossover</span> Region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tajima, H.; van Wyk, P.; Hanai, R.; Kagamihara, D.; Inotani, D.; Horikoshi, M.; Ohashi, Y.</p> <p>2017-06-01</p> <p>We investigate thermodynamic properties and effects of quantum fluctuations in the Bardeen-Cooper-Schrieffer (BCS)-Bose-Einstein condensation (BEC) <span class="hlt">crossover</span> region of a superfluid Fermi gas in the low-temperature limit. Including strong-coupling corrections within the framework of an extended T-matrix approximation, we numerically compute the isothermal compressibility χ _n. While quantum fluctuation effects on χ _n in the strong-coupling BEC regime are explained by the quantum depletion due to a repulsive interaction between tightly bound molecules, effects of self-energy shift on the Fermi chemical potential are found to enhance χ _n in the weak-coupling BCS region. We also show that the calculated χ _n agrees well with the recent <span class="hlt">experiment</span> on a ^6Li Fermi gas done from the weak-coupling region to the unitarity limit. Our result would be useful for the study of many-body quantum corrections in the BCS-BEC <span class="hlt">crossover</span> region of a strongly interacting Fermi superfluid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16267132','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16267132"><span>Relation between the Widom line and the dynamic <span class="hlt">crossover</span> in systems with a liquid-liquid phase transition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xu, Limei; Kumar, Pradeep; Buldyrev, S V; Chen, S-H; Poole, P H; Sciortino, F; Stanley, H E</p> <p>2005-11-15</p> <p>We investigate, for two water models displaying a liquid-liquid critical point, the relation between changes in dynamic and thermodynamic anomalies arising from the presence of the liquid-liquid critical point. We find a correlation between the dynamic <span class="hlt">crossover</span> and the locus of specific heat maxima C(P)(max) ("Widom line") emanating from the critical point. Our findings are consistent with a possible relation between the previously hypothesized liquid-liquid phase transition and the transition in the dynamics recently observed in neutron scattering <span class="hlt">experiments</span> on confined water. More generally, we argue that this connection between C(P)(max) and dynamic <span class="hlt">crossover</span> is not limited to the case of water, a hydrogen bond network-forming liquid, but is a more general feature of crossing the Widom line. Specifically, we also study the Jagla potential, a spherically symmetric two-scale potential known to possess a liquid-liquid critical point, in which the competition between two liquid structures is generated by repulsive and attractive ramp interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1283834','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1283834"><span>Relation between the Widom line and the dynamic <span class="hlt">crossover</span> in systems with a liquid–liquid phase transition</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Xu, Limei; Kumar, Pradeep; Buldyrev, S. V.; Chen, S.-H.; Poole, P. H.; Sciortino, F.; Stanley, H. E.</p> <p>2005-01-01</p> <p>We investigate, for two water models displaying a liquid–liquid critical point, the relation between changes in dynamic and thermodynamic anomalies arising from the presence of the liquid–liquid critical point. We find a correlation between the dynamic <span class="hlt">crossover</span> and the locus of specific heat maxima \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}C_{P}^{{\\mathrm{max}}}\\end{equation*}\\end{document} (“Widom line”) emanating from the critical point. Our findings are consistent with a possible relation between the previously hypothesized liquid–liquid phase transition and the transition in the dynamics recently observed in neutron scattering <span class="hlt">experiments</span> on confined water. More generally, we argue that this connection between \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}C_{P}^{{\\mathrm{max}}}\\end{equation*}\\end{document} and dynamic <span class="hlt">crossover</span> is not limited to the case of water, a hydrogen bond network-forming liquid, but is a more general feature of crossing the Widom line. Specifically, we also study the Jagla potential, a spherically symmetric two-scale potential known to possess a liquid–liquid critical point, in which the competition between two liquid structures is generated by repulsive and attractive ramp interactions. PMID:16267132</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23368134','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23368134"><span>Fragile-strong fluid <span class="hlt">crossover</span> and universal relaxation times in a confined hard-disk fluid.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yamchi, Mahdi Zaeifi; Ashwin, S S; Bowles, Richard K</p> <p>2012-11-30</p> <p>We show that a system of hard disks confined to a narrow channel exhibits a fragile-strong fluid <span class="hlt">crossover</span> located at the maximum of the isobaric heat capacity and that the relaxation times for different channel widths fall onto a single master curve when rescaled by the relaxation times and temperatures of the <span class="hlt">crossover</span>. Calculations of the configurational entropy and the inherent structure equation of state find that the <span class="hlt">crossover</span> is related to properties of the jamming landscape for the model but that the Adam-Gibbs relation does not predict the relaxation behavior. We also show that a facilitated dynamics description of the system, where kinetically excited regions are identified with local packing arrangements of the disks, successfully describes the fragile-strong <span class="hlt">crossover</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060037525&hterms=methanol&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmethanol','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060037525&hterms=methanol&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmethanol"><span>Studies on Methanol <span class="hlt">Crossover</span> in Liquid-Feed Direct Methanol Pem Fuel Cells</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Narayanan, S. R.</p> <p>1995-01-01</p> <p>The performance of liquid feed direct methanol fuel cells using various types of Nafion membranes as the solid polymer electrolyte have been studied. The rate of fuel <span class="hlt">crossover</span> and electrical performance has been measured for cells with Nafion membranes of various thicknesses and equivalent weights. The <span class="hlt">crossover</span> rate is found to decrease with increasing thickness and applied current. The dependence of <span class="hlt">crossover</span> rate on current density can be understood in terms of a simple linear diffusion model which suggests that the <span class="hlt">crossover</span> rate can be influenced by the electrode structure in addition to the membrane. The studies suggest that Nafion EW 1500 is a very promising alternate to Nafion EW 1100 for direct methanol fuel cells.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21965170','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21965170"><span>Design evaluation and optimisation in <span class="hlt">crossover</span> pharmacokinetic studies analysed by nonlinear mixed effects models.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nguyen, Thu Thuy; Bazzoli, Caroline; Mentré, France</p> <p>2012-05-20</p> <p>Bioequivalence or interaction trials are commonly studied in <span class="hlt">crossover</span> design and can be analysed by nonlinear mixed effects models as an alternative to noncompartmental approach. We propose an extension of the population Fisher information matrix in nonlinear mixed effects models to design <span class="hlt">crossover</span> pharmacokinetic trials, using a linearisation of the model around the random effect expectation, including within-subject variability and discrete covariates fixed or changing between periods. We use the expected standard errors of treatment effect to compute the power for the Wald test of comparison or equivalence and the number of subjects needed for a given power. We perform various simulations mimicking <span class="hlt">crossover</span> two-period trials to show the relevance of these developments. We then apply these developments to design a <span class="hlt">crossover</span> pharmacokinetic study of amoxicillin in piglets and implement them in the new version 3.2 of the r function PFIM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26356084','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26356084"><span>Measuring Meiotic <span class="hlt">Crossovers</span> via Multi-Locus Genotyping of Single Pollen Grains in Barley.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dreissig, Steven; Fuchs, Jörg; Cápal, Petr; Kettles, Nicola; Byrne, Ed; Houben, Andreas</p> <p>2015-01-01</p> <p>The detection of meiotic <span class="hlt">crossovers</span> in crop plants currently relies on scoring DNA markers in a segregating population or cytological visualization. We investigated the feasibility of using flow-sorted haploid nuclei, Phi29 DNA polymerase-based whole-genome-amplification (WGA) and multi-locus KASP-genotyping to measure meiotic <span class="hlt">crossovers</span> in individual barley pollen grains. To demonstrate the proof of concept, we used 24 gene-based physically mapped single nucleotide polymorphisms to genotype the WGA products of 50 single pollen nuclei. The number of <span class="hlt">crossovers</span> per chromosome, recombination frequencies along chromosome 3H and segregation distortion were analysed and compared to a doubled haploid (DH) population of the same genotype. The number of <span class="hlt">crossovers</span> and chromosome wide recombination frequencies show that this approach is able to produce results that resemble those obtained from other methods in a biologically meaningful way. Only the segregation distortion was found to be lower in the pollen population than in DH plants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060037525&hterms=fuel+cell+electrode+model&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dfuel%2Bcell%2Belectrode%2Bmodel','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060037525&hterms=fuel+cell+electrode+model&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dfuel%2Bcell%2Belectrode%2Bmodel"><span>Studies on Methanol <span class="hlt">Crossover</span> in Liquid-Feed Direct Methanol Pem Fuel Cells</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Narayanan, S. R.</p> <p>1995-01-01</p> <p>The performance of liquid feed direct methanol fuel cells using various types of Nafion membranes as the solid polymer electrolyte have been studied. The rate of fuel <span class="hlt">crossover</span> and electrical performance has been measured for cells with Nafion membranes of various thicknesses and equivalent weights. The <span class="hlt">crossover</span> rate is found to decrease with increasing thickness and applied current. The dependence of <span class="hlt">crossover</span> rate on current density can be understood in terms of a simple linear diffusion model which suggests that the <span class="hlt">crossover</span> rate can be influenced by the electrode structure in addition to the membrane. The studies suggest that Nafion EW 1500 is a very promising alternate to Nafion EW 1100 for direct methanol fuel cells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25002507','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25002507"><span>Spin <span class="hlt">crossover</span> in ferropericlase and velocity heterogeneities in the lower mantle.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wu, Zhongqing; Wentzcovitch, Renata M</p> <p>2014-07-22</p> <p>Deciphering the origin of seismic velocity heterogeneities in the mantle is crucial to understanding internal structures and processes at work in the Earth. The spin <span class="hlt">crossover</span> in iron in ferropericlase (Fp), the second most abundant phase in the lower mantle, introduces unfamiliar effects on seismic velocities. First-principles calculations indicate that anticorrelation between shear velocity (VS) and bulk sound velocity (Vφ) in the mantle, usually interpreted as compositional heterogeneity, can also be produced in homogeneous aggregates containing Fp. The spin <span class="hlt">crossover</span> also suppresses thermally induced heterogeneity in longitudinal velocity (VP) at certain depths but not in VS. This effect is observed in tomography models at conditions where the spin <span class="hlt">crossover</span> in Fp is expected in the lower mantle. In addition, the one-of-a-kind signature of this spin <span class="hlt">crossover</span> in the RS/P (∂ ln VS/∂ ln VP) heterogeneity ratio might be a useful fingerprint to detect the presence of Fp in the lower mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990PhRvA..42.3512N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990PhRvA..42.3512N"><span>Phase transition and <span class="hlt">crossover</span> in diffusion-limited aggregation with reaction times</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nagatani, Takashi; Stanley, H. Eugene</p> <p>1990-09-01</p> <p>A generalized diffusion-limited aggregation (DLA) with reaction times that has been proposed by Bunde and Miyazima [Phys. Rev. A 38, 2099 (1988)] is considered. <span class="hlt">Crossover</span> from the DLA to the diffusion-limited self-avoiding walk (DLSAW) is investigated by using the two-parameter position-space renormalization-group method. The <span class="hlt">crossover</span> exponent and the <span class="hlt">crossover</span> radius are calculated. The geometrical phase transition between DLA and DLSAW found by Bunde and Miyajima is analyzed by making use of the three-parameter position-space renormalization-group method. A global flow diagram in the three-parameter space is obtained. Above the percolation threshold all the renormalization flows are merged into the DLA point. Below the threshold all the renormalization flows are merged into the DLSAW point. When the reaction time is large, the double-<span class="hlt">crossover</span> phenomenon occurs below the threshold.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2646836','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2646836"><span>A Fine-Structure Map of Spontaneous Mitotic <span class="hlt">Crossovers</span> in the Yeast Saccharomyces cerevisiae</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lee, Phoebe S.; Greenwell, Patricia W.; Dominska, Margaret; Gawel, Malgorzata; Hamilton, Monica; Petes, Thomas D.</p> <p>2009-01-01</p> <p>Homologous recombination is an important mechanism for the repair of DNA damage in mitotically dividing cells. Mitotic <span class="hlt">crossovers</span> between homologues with heterozygous alleles can produce two homozygous daughter cells (loss of heterozygosity), whereas <span class="hlt">crossovers</span> between repeated genes on non-homologous chromosomes can result in translocations. Using a genetic system that allows selection of daughter cells that contain the reciprocal products of mitotic crossing over, we mapped <span class="hlt">crossovers</span> and gene conversion events at a resolution of about 4 kb in a 120-kb region of chromosome V of Saccharomyces cerevisiae. The gene conversion tracts associated with mitotic <span class="hlt">crossovers</span> are much longer (averaging about 12 kb) than the conversion tracts associated with meiotic recombination and are non-randomly distributed along the chromosome. In addition, about 40% of the conversion events have patterns of marker segregation that are most simply explained as reflecting the repair of a chromosome that was broken in G1 of the cell cycle. PMID:19282969</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title49-vol4/pdf/CFR-2011-title49-vol4-sec236-203.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title49-vol4/pdf/CFR-2011-title49-vol4-sec236-203.pdf"><span>49 CFR 236.203 - Hand operated <span class="hlt">crossover</span> between main tracks; protection.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-10-01</p> <p>...) Facing point locks on both switches of the <span class="hlt">crossover</span>, with both locks operated by a single lever, or (c... matter on the rail prevents effective shunting; (2) Where facing point locks with a single lever are...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title49-vol4/pdf/CFR-2014-title49-vol4-sec236-203.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title49-vol4/pdf/CFR-2014-title49-vol4-sec236-203.pdf"><span>49 CFR 236.203 - Hand operated <span class="hlt">crossover</span> between main tracks; protection.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-10-01</p> <p>...) Facing point locks on both switches of the <span class="hlt">crossover</span>, with both locks operated by a single lever, or (c... matter on the rail prevents effective shunting; (2) Where facing point locks with a single lever are...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title49-vol4/pdf/CFR-2012-title49-vol4-sec236-203.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title49-vol4/pdf/CFR-2012-title49-vol4-sec236-203.pdf"><span>49 CFR 236.203 - Hand operated <span class="hlt">crossover</span> between main tracks; protection.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-10-01</p> <p>...) Facing point locks on both switches of the <span class="hlt">crossover</span>, with both locks operated by a single lever, or (c... matter on the rail prevents effective shunting; (2) Where facing point locks with a single lever are...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title49-vol4/pdf/CFR-2013-title49-vol4-sec236-203.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title49-vol4/pdf/CFR-2013-title49-vol4-sec236-203.pdf"><span>49 CFR 236.203 - Hand operated <span class="hlt">crossover</span> between main tracks; protection.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-10-01</p> <p>...) Facing point locks on both switches of the <span class="hlt">crossover</span>, with both locks operated by a single lever, or (c... matter on the rail prevents effective shunting; (2) Where facing point locks with a single lever are...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title49-vol4/pdf/CFR-2010-title49-vol4-sec236-203.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title49-vol4/pdf/CFR-2010-title49-vol4-sec236-203.pdf"><span>49 CFR 236.203 - Hand operated <span class="hlt">crossover</span> between main tracks; protection.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-10-01</p> <p>...) Facing point locks on both switches of the <span class="hlt">crossover</span>, with both locks operated by a single lever, or (c... matter on the rail prevents effective shunting; (2) Where facing point locks with a single lever are...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22413009','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22413009"><span>First principles study of thermal conductivity <span class="hlt">cross-over</span> in nanostructured zinc-chalcogenides</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Katre, Ankita; Madsen, Georg K. H.; Togo, Atsushi; Tanaka, Isao</p> <p>2015-01-28</p> <p>Systematic first principles studies of zinc-chalcogenides have been performed to understand their thermal transport behaviour. We have applied the Boltzmann transport equation in the relaxation time approximation to calculate the thermal conductivity of ZnS, ZnSe, and ZnTe. We find a thermal conductivity <span class="hlt">cross-over</span> between ZnS and ZnSe at nanostructure sizes around 0.1–0.2 μm and explain this in terms of the different contributions of phonon modes in these materials. We study the effect of nanostructuring using both the diffusive boundary scattering and confined mean free path limit and discuss the variations in the results. Furthermore, we show the strong influence of isotope scattering on the thermal conductivity. The calculated thermal conductivity is found to be strongly dependent on the volume and we explain the observed differences between local density and generalized gradient approximation calculations. We compare further calculated thermal properties, such as the thermal expansion coefficient, to <span class="hlt">experiment</span> to validate our approach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1364138-reentrant-resistive-behavior-dimensional-crossover-disordered-superconducting-tin-films','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1364138-reentrant-resistive-behavior-dimensional-crossover-disordered-superconducting-tin-films"><span>Reentrant resistive behavior and dimensional <span class="hlt">crossover</span> in disordered superconducting TiN films</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Postolova, Svetlana V.; Mironov, Alexey Yu.; Baklanov, Mikhail R.; ...</p> <p>2017-05-11</p> <p>A reentrant temperature dependence of the normal state resistance often referred to as the N-shaped temperature dependence, is omnipresent in disordered superconductors – ranging from high-temperature cuprates to ultrathin superconducting films – that <span class="hlt">experience</span> superconductor-to-insulator transition. Yet, despite the ubiquity of this phenomenon its origin still remains a subject of debate. Here we investigate strongly disordered superconducting TiN films and demonstrate universality of the reentrant behavior. We offer a quantitative description of the N-shaped resistance curve. We show that upon cooling down the resistance first decreases linearly with temperature and then passes through the minimum that marks the 3D-2D crossovermore » in the system. In the 2D temperature range the resistance first grows with decreasing temperature due to quantum contributions and eventually drops to zero as the system falls into a superconducting state. As a result, our findings demonstrate the prime importance of disorder in dimensional <span class="hlt">crossover</span> effects.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvB..91h5430B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvB..91h5430B"><span>Hexagonal AlN: Dimensional-<span class="hlt">crossover</span>-driven band-gap transition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bacaksiz, C.; Sahin, H.; Ozaydin, H. D.; Horzum, S.; Senger, R. T.; Peeters, F. M.</p> <p>2015-02-01</p> <p>Motivated by a recent <span class="hlt">experiment</span> that reported the successful synthesis of hexagonal (h ) AlN [Tsipas et al., Appl. Phys. Lett. 103, 251605 (2013), 10.1063/1.4851239], we investigate structural, electronic, and vibrational properties of bulk, bilayer, and monolayer structures of h -AlN by using first-principles calculations. We show that the hexagonal phase of the bulk h -AlN is a stable direct-band-gap semiconductor. The calculated phonon spectrum displays a rigid-layer shear mode at 274 cm-1 and an Eg mode at 703 cm-1, which are observable by Raman measurements. In addition, single-layer h -AlN is an indirect-band-gap semiconductor with a nonmagnetic ground state. For the bilayer structure, A A' -type stacking is found to be the most favorable one, and interlayer interaction is strong. While N -layered h -AlN is an indirect-band-gap semiconductor for N =1 -9 , we predict that thicker structures (N ≥10 ) have a direct band gap at the Γ point. The number-of-layer-dependent band-gap transitions in h -AlN is interesting in that it is significantly different from the indirect-to-direct <span class="hlt">crossover</span> obtained in the transition-metal dichalcogenides.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhRvB..81v4102Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhRvB..81v4102Z"><span>Phase diagram of Ti50-xNi50+x : <span class="hlt">Crossover</span> from martensite to strain glass</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Zhen; Wang, Yu; Wang, Dong; Zhou, Yumei; Otsuka, Kazuhiro; Ren, Xiaobing</p> <p>2010-06-01</p> <p>We systematically investigated the variation in transition behavior and physical properties over a wide excess Ni (acting as defect) concentration range (x=0-2.5) in Ti50-xNi50+x alloys. This enables the establishment of an updated quantitative phase diagram for this important system. The phase diagram shows not only the well-known parent phase and martensite phase but also a premartensitic state and a strain glass state. Our <span class="hlt">experiments</span> were able to determine quantitatively the borders of these states, the latter two having been unclear so far. The new phase diagram shows that a <span class="hlt">crossover</span> from martensite to strain glass occurs at x=1.3 , and the appearance of a “premartensitic phase” below a critical temperature Tnd for defect-containing compositions (x>0) . We propose that point defects (excess Ni here) play two roles in a ferroelastic/martensitic system: (i) changing the thermodynamic driving force for the formation of long-range strain order (martensite) and (ii) creating random local stress that favors a premartensitic nanostructure and strain glass. Our work enables a simple explanation for several long-standing puzzles, such as the appearance of premartensitic nanostructure, the vanishing of transition latent heat with increasing Ni content and the anomalous negative temperature coefficient of electrical resistivity in Ni-rich Ti-Ni alloys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvF...1f4101C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvF...1f4101C"><span><span class="hlt">Crossover</span> from shear-driven to thermally activated drainage of liquid-infused microscale capillaries</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Colosqui, Carlos E.; Wexler, Jason S.; Liu, Ying; Stone, Howard A.</p> <p>2016-10-01</p> <p>The shear-driven drainage of capillary grooves filled with viscous liquid is a dynamic wetting phenomenon relevant to numerous industrial processes and lubricant-infused surfaces for drag reduction and antifouling. Prior work has reported that a finite length L∞ of the capillary groove can remain indefinitely filled with liquid even when large shear stresses are applied. The mechanism preventing full drainage is attributed to a balance between the shear-driven flow and a counterflow driven by capillary pressures caused by deformation of the free surface. In this work, we examine closely the approach to the final equilibrium length L∞ and report a <span class="hlt">crossover</span> to a slow drainage regime that cannot be described by conventional dynamic models considering solely hydrodynamic and capillary forces. The slow drainage regime observed in <span class="hlt">experiments</span> can be instead modeled by a kinetic equation describing a sequence of random thermally activated transitions between multiple metastable states caused by surface defects with nanoscale dimensions. Our findings provide insights on the critical role that natural or engineered surface roughness with nanoscale dimensions can play in the imbibition and drainage of capillaries and other dynamic wetting processes in microscale systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvB..94p5150P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvB..94p5150P"><span>Effective Hamiltonian based Monte Carlo for the BCS to BEC <span class="hlt">crossover</span> in the attractive Hubbard model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pasrija, Kanika; Chakraborty, Prabuddha B.; Kumar, Sanjeev</p> <p>2016-10-01</p> <p>We present an effective Hamiltonian based real-space approach for studying the weak-coupling BCS to the strong-coupling Bose-Einstein condensate <span class="hlt">crossover</span> in the two-dimensional attractive Hubbard model at finite temperatures. We introduce and justify an effective classical Hamiltonian to describe the thermal fluctuations of the relevant auxiliary fields. Our results for Tc and phase diagrams compare very well with those obtained from more sophisticated and CPU-intensive numerical methods. We demonstrate that the method works in the presence of disorder and can be a powerful tool for a real-space description of the effect of disorder on superconductivity. From a combined analysis of the superconducting order parameter, the distribution of auxiliary fields, and the quasiparticle density of states, we identify the regions of metallic, insulating, superconducting, and pseudogapped behavior. Our finding of the importance of phase fluctuations for the pseudogap behavior is consistent with the conclusions drawn from recent <span class="hlt">experiments</span> on NbN superconductors. The method can be generalized to study superconductors with nontrivial order-parameter symmetries by identifying the relevant auxiliary variables.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23873735','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23873735"><span>Propagation of biochirality: <span class="hlt">crossovers</span> and nonclassical crystallization kinetics of aspartic acid in water.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Tu; Lin, Yu Kun; Tsai, Ya Chung; Lee, Hung Lin</p> <p>2013-11-01</p> <p>All experimental procedures discussed could be treated as a screening tool for probing the existence of molecular association among the chiral molecules and the solvent system. The molecular association phases of a racemic conglomerate solution (CS) and a racemic compound solution (RCS), and the templating effect of aspartic acid solid surface were observed to minimize the chance of redissolving racemic conglomerate and racemic compound aspartic acid in water and reforming an RCS in <span class="hlt">crossovers</span> <span class="hlt">experiments</span>. Only 1 %wt% of l-aspartic acid was adequate enough to induce a transformation from a racemic compound aspartic acid to a racemic conglomerate aspartic acid. This would make the propagation of biochirality more feasible and sound. However, tetrapeptide, (l-aspartic acid)4 , failed to induce enantioseparation as templates purely by crystallization. Nonclassical crystallization theory was needed to take into account the existence of a CS. Fundamental parameters of the crystallization kinetics such as the induction time, interfacial energy, Gibbs energetic barrier, nucleation rate, and critical size of stable nuclei of: (i) racemic compound aspartic acid, (ii) racemic compound aspartic acid seeded with 1 %wt% l-aspartic acid, (iii) racemic conglomerate aspartic acid, and (iv) l-aspartic acid were evaluated and compared with different initial supersaturation ratios. Morphological studies of crystals grown from the crystallization kinetics were also carried out. © 2013 Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhRvA..89e3604A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhRvA..89e3604A"><span>Inhomogeneous BCS-BEC <span class="hlt">crossover</span> for trapped cold atoms in optical lattices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Amaricci, A.; Privitera, A.; Capone, M.</p> <p>2014-05-01</p> <p>The BCS-BEC (Bose-Einstein condensation) <span class="hlt">crossover</span> in a lattice is a powerful paradigm that describes how a superconductor deviates from the Bardeen-Cooper-Schrieffer physics as the attractive interaction increases. Optical lattices loaded with binary mixtures of cold atoms allow one to access this phenomenon experimentally in a clean and controlled way. We show that, however, the possibility to study this phenomenon in actual cold-atoms <span class="hlt">experiments</span> is limited by the effect of the trapping potential. Real-space dynamical mean-field theory calculations show indeed that interactions and the confining potential conspire to pack the fermions in the center of the trap, which approaches a band insulator when the attraction becomes sizeable. Interestingly, the energy gap is spatially more homogeneous than the superfluid condensate order parameter. We show how this physics reflects in several observables, and we propose an alternative strategy to disentangle the effect of the harmonic potential and measure the intrinsic properties resulting from the interaction strength.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5580608','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5580608"><span>A Randomized <span class="hlt">Crossover</span> Trial on Acute Stress-Related Physiological Responses to Mountain Hiking</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Grafetstätter, Carina; Hartl, Arnulf; Kopp, Martin</p> <p>2017-01-01</p> <p>Green exercise, defined as physical activity in natural environments, might have positive effects on stress-related physiological measures. Little is known about the acute effects of green exercise bouts lasting longer than 60 min. Therefore, the aim of the present study was to analyze the acute effects of a three-hour green exercise intervention (mountain hiking) on stress-related physiological responses. Using a randomized <span class="hlt">crossover</span> design, 42 healthy participants were exposed to three different conditions in a field-based <span class="hlt">experiment</span>: outdoor mountain hiking, indoor treadmill walking, and sedentary control condition (three hours each). At baseline and at follow-up (five minutes after the condition), stress-related physiological responses (salivary cortisol, blood pressure, and heart rate variability) were measured. Salivary cortisol decreased in all conditions, but showed a larger decrease after both mountain hiking and treadmill walking compared to the sedentary control situation (partial η2 = 0.10). No differences were found between mountain hiking and treadmill walking in salivary cortisol. In heart rate variability and blood pressure, changes from baseline to follow-up did not significantly differ between the three conditions. The results indicate that three hours of hiking indoors or outdoors elicits positive effects on salivary cortisol concentration. Environmental effects seem to play a minor role in salivary cortisol, blood pressure, and heart rate variability. PMID:28800067</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28800067','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28800067"><span>A Randomized <span class="hlt">Crossover</span> Trial on Acute Stress-Related Physiological Responses to Mountain Hiking.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Niedermeier, Martin; Grafetstätter, Carina; Hartl, Arnulf; Kopp, Martin</p> <p>2017-08-11</p> <p>Green exercise, defined as physical activity in natural environments, might have positive effects on stress-related physiological measures. Little is known about the acute effects of green exercise bouts lasting longer than 60 min. Therefore, the aim of the present study was to analyze the acute effects of a three-hour green exercise intervention (mountain hiking) on stress-related physiological responses. Using a randomized <span class="hlt">crossover</span> design, 42 healthy participants were exposed to three different conditions in a field-based <span class="hlt">experiment</span>: outdoor mountain hiking, indoor treadmill walking, and sedentary control condition (three hours each). At baseline and at follow-up (five minutes after the condition), stress-related physiological responses (salivary cortisol, blood pressure, and heart rate variability) were measured. Salivary cortisol decreased in all conditions, but showed a larger decrease after both mountain hiking and treadmill walking compared to the sedentary control situation (partial η² = 0.10). No differences were found between mountain hiking and treadmill walking in salivary cortisol. In heart rate variability and blood pressure, changes from baseline to follow-up did not significantly differ between the three conditions. The results indicate that three hours of hiking indoors or outdoors elicits positive effects on salivary cortisol concentration. Environmental effects seem to play a minor role in salivary cortisol, blood pressure, and heart rate variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18698797','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18698797"><span>Characterization of nonspecific <span class="hlt">crossover</span> in split-flow thin channel fractionation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Williams, P Stephen; Hoyos, Mauricio; Kurowski, Pascal; Salhi, Dorra; Moore, Lee R; Zborowski, Maciej</p> <p>2008-09-15</p> <p>Split-flow thin channel (SPLITT) fractionation is a technique for continuous separation of particles or macromolecules in a fluid stream into fractions according to the lateral migration induced by application of a field perpendicular to the direction of flow. Typical applications have involved isolation of different fractions from a polydisperse sample. Some specialized applications involve the separation of the fraction influenced by the transverse field from the fraction that is not. For example, immunomagnetically labeled biological cells may be separated from nonlabeled cells with the application of a transverse magnetic field gradient. In such cases, it may be critically important to minimize contamination of the labeled cells with nonlabeled cells while at the same time maximizing the throughput. Such contamination is known as nonspecific <span class="hlt">crossover</span> (NSC) and refers to the real or apparent migration of nonmobile particles or cells across stream lines with the mobile material. The possible mechanisms for NSC are discussed, and experimental results interpreted in terms of shear-induced diffusion (SID) caused by viscous interactions between particles in a sheared flow. It is concluded that SID may contribute to NSC, but that further <span class="hlt">experiments</span> and mathematical modeling are necessary to more fully explore the phenomenon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1237164','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1237164"><span>Revealing the mechanism of the viscous-to-elastic <span class="hlt">crossover</span> in liquids</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bolmatov, Dima; Zhernenkov, Mikhail; Zav'yalov, Dmitry; Stoupin, Stanislav; Cai, Yong Q.; Cunsolo, Alessandro</p> <p>2015-07-18</p> <p>In our work, we report on inelastic X-ray scattering <span class="hlt">experiments</span> combined with the molecular dynamics simulations on deeply supercritical Ar. Our results unveil the mechanism and regimes of sound propagation in the liquid matter and provide compelling evidence for the adiabatic-to-isothermal longitudinal sound propagation transition. We introduce a Hamiltonian predicting low-frequency transverse sound propagation gaps, which is confirmed by experimental findings and molecular dynamics calculations. As a result, a universal link is established between the positive sound dispersion (PSD) phenomenon and the origin of transverse sound propagation revealing the viscous-to-elastic <span class="hlt">crossover</span> in liquids. The PSD and transverse phononic excitations evolve consistently with theoretical predictions. Both can be considered as a universal fingerprint of the dynamic response of a liquid, which is also observable in a subdomain of supercritical phase. Furthermore, the simultaneous disappearance of both these effects at elevated temperatures is a manifestation of the Frenkel line. We expect that these findings will advance the current understanding of fluids under extreme thermodynamic conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1237164-revealing-mechanism-viscous-elastic-crossover-liquids','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1237164-revealing-mechanism-viscous-elastic-crossover-liquids"><span>Revealing the mechanism of the viscous-to-elastic <span class="hlt">crossover</span> in liquids</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Bolmatov, Dima; Zhernenkov, Mikhail; Zav'yalov, Dmitry; ...</p> <p>2015-07-18</p> <p>In our work, we report on inelastic X-ray scattering <span class="hlt">experiments</span> combined with the molecular dynamics simulations on deeply supercritical Ar. Our results unveil the mechanism and regimes of sound propagation in the liquid matter and provide compelling evidence for the adiabatic-to-isothermal longitudinal sound propagation transition. We introduce a Hamiltonian predicting low-frequency transverse sound propagation gaps, which is confirmed by experimental findings and molecular dynamics calculations. As a result, a universal link is established between the positive sound dispersion (PSD) phenomenon and the origin of transverse sound propagation revealing the viscous-to-elastic <span class="hlt">crossover</span> in liquids. The PSD and transverse phononic excitations evolvemore » consistently with theoretical predictions. Both can be considered as a universal fingerprint of the dynamic response of a liquid, which is also observable in a subdomain of supercritical phase. Furthermore, the simultaneous disappearance of both these effects at elevated temperatures is a manifestation of the Frenkel line. We expect that these findings will advance the current understanding of fluids under extreme thermodynamic conditions.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3715419','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3715419"><span>Interplay between Structure-Specific Endonucleases for <span class="hlt">Crossover</span> Control during Caenorhabditis elegans Meiosis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kim, Hyun-Min; Meyer, Katherine; Colaiácovo, Monica P.</p> <p>2013-01-01</p> <p>The number and distribution of <span class="hlt">crossover</span> events are tightly regulated at prophase of meiosis I. The resolution of Holliday junctions by structure-specific endonucleases, including MUS-81, SLX-1, XPF-1 and GEN-1, is one of the main mechanisms proposed for <span class="hlt">crossover</span> formation. However, how these nucleases coordinately resolve Holliday junctions is still unclear. Here we identify both the functional overlap and differences between these four nucleases regarding their roles in <span class="hlt">crossover</span> formation and control in the Caenorhabditis elegans germline. We show that MUS-81, XPF-1 and SLX-1, but not GEN-1, can bind to HIM-18/SLX4, a key scaffold for nucleases. Analysis of synthetic mitotic defects revealed that MUS-81 and SLX-1, but not XPF-1 and GEN-1, have overlapping roles with the Bloom syndrome helicase ortholog, HIM-6, supporting their in vivo roles in processing recombination intermediates. Taking advantage of the ease of genetic analysis and high-resolution imaging afforded by C. elegans, we examined <span class="hlt">crossover</span> designation, frequency, distribution and chromosomal morphology in single, double, triple and quadruple mutants of the structure-specific endonucleases. This revealed that XPF-1 functions redundantly with MUS-81 and SLX-1 in executing <span class="hlt">crossover</span> formation during meiotic double-strand break repair. Analysis of <span class="hlt">crossover</span> distribution revealed that SLX-1 is required for <span class="hlt">crossover</span> suppression at the center region of the autosomes. Finally, analysis of chromosome morphology in oocytes at late meiosis I stages uncovered that SLX-1 and XPF-1 promote meiotic chromosomal stability by preventing formation of chromosomal abnormalities. We propose a model in which coordinate action between structure-specific nucleases at different chromosome domains, namely MUS-81, SLX-1 and XPF-1 at the arms and SLX-1 at the center region, exerts positive and negative regulatory roles, respectively, for <span class="hlt">crossover</span> control during C. elegans meiosis. PMID:23874210</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22558168','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22558168"><span>Empirical power and sample size calculations for cluster-randomized and cluster-randomized <span class="hlt">crossover</span> studies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Reich, Nicholas G; Myers, Jessica A; Obeng, Daniel; Milstone, Aaron M; Perl, Trish M</p> <p>2012-01-01</p> <p>In recent years, the number of studies using a cluster-randomized design has grown dramatically. In addition, the cluster-randomized <span class="hlt">crossover</span> design has been touted as a methodological advance that can increase efficiency of cluster-randomized studies in certain situations. While the cluster-randomized <span class="hlt">crossover</span> trial has become a popular tool, standards of design, analysis, reporting and implementation have not been established for this emergent design. We address one particular aspect of cluster-randomized and cluster-randomized <span class="hlt">crossover</span> trial design: estimating statistical power. We present a general framework for estimating power via simulation in cluster-randomized studies with or without one or more <span class="hlt">crossover</span> periods. We have implemented this framework in the clusterPower software package for R, freely available online from the Comprehensive R Archive Network. Our simulation framework is easy to implement and users may customize the methods used for data analysis. We give four examples of using the software in practice. The clusterPower package could play an important role in the design of future cluster-randomized and cluster-randomized <span class="hlt">crossover</span> studies. This work is the first to establish a universal method for calculating power for both cluster-randomized and cluster-randomized clinical trials. More research is needed to develop standardized and recommended methodology for cluster-randomized <span class="hlt">crossover</span> studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26583142','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26583142"><span><span class="hlt">Crossover</span> versus Stabilometric Platform for the Treatment of Balance Dysfunction in Parkinson's Disease: A Randomized Study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Frazzitta, G; Bossio, F; Maestri, R; Palamara, G; Bera, R; Ferrazzoli, D</p> <p>2015-01-01</p> <p>Balance dysfunctions are a major challenge in the treatment of Parkinson's disease (PD). Previous studies have shown that rehabilitation can play a role in their treatment. In this study, we have compared the efficacy of two different devices for balance training: stabilometric platform and <span class="hlt">crossover</span>. We have enrolled 60 PD patients randomly assigned to two groups. The first one (stabilometric group) performed a 4-week cycle of balance training, using the stabilometric platform, whereas the second one (<span class="hlt">crossover</span> group) performed a 4-week cycle of balance training, using the <span class="hlt">crossover</span>. The outcome measures used were Unified Parkinson's Disease Rating Scale (UPDRS) part II, Berg Balance Scale (BBS), Timed Up and Go (TUG), and Six Minutes Walking Test (6MWT). Results showed that TUG, BBS, and UPDRS II improved in both groups. There was not difference in the efficacy of the two balance treatments. Patients in both groups improved also the meters walked in the 6MWT at the end of rehabilitation, but the improvement was better for patients performing <span class="hlt">crossover</span> training. Our results show that the <span class="hlt">crossover</span> and the stabilometric platform have the same effect on balance dysfunction of Parkinsonian patients, while <span class="hlt">crossover</span> gets better results on the walking capacity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AIPC..854..215M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AIPC..854..215M"><span>Analysis of <span class="hlt">Crossovers</span> in the Interbeat Sequences of Elderly Individuals and Heart Failure Patients</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muñoz-Diosdado, A.; del Río Correa, J. L.</p> <p>2006-09-01</p> <p>Many physical and biological systems exhibit complex behavior characterized by long-range power-law correlations. Detrended fluctuation analysis (DFA) is a scaling analysis method that provides a scaling parameter to represent the correlation properties of a signal. The study of interbeat sequences with the DFA method has revealed the presence of <span class="hlt">crossovers</span> associated with physiological aging and heart with failure; the hinges present in the <span class="hlt">crossover</span> region from both the elderly healthy individuals and the patients with congestive heart failure (CHF) are in opposite directions. The interbeat sequences of healthy young persons do not show <span class="hlt">crossovers</span>. In this paper we study interbeat time series of healthy young and elderly persons and patients with CHF. We use the DFA-m method, where m refers to the order of the polynomial function used for the fitting. For instance, DFA-2 filters linear trends and DFA-3 filters quadratic trends. We found that the presence of the <span class="hlt">crossovers</span> and the direction of the hinges are conserved when we apply the DFA method for different values of m. Therefore we conclude that the DFA-m method is a reliable method to accurately quantify correlations in interbeat time series even if there are polynomial trends. We can characterize the <span class="hlt">crossovers</span> and we can conclude that the <span class="hlt">crossovers</span> are not a result of the trends; they are part of the system dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5222560','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5222560"><span>Local chromosome context is a major determinant of <span class="hlt">crossover</span> pathway biochemistry during budding yeast meiosis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Medhi, Darpan; Goldman, Alastair SH; Lichten, Michael</p> <p>2016-01-01</p> <p>The budding yeast genome contains regions where meiotic recombination initiates more frequently than in others. This pattern parallels enrichment for the meiotic chromosome axis proteins Hop1 and Red1. These proteins are important for Spo11-catalyzed double strand break formation; their contribution to <span class="hlt">crossover</span> recombination remains undefined. Using the sequence-specific VMA1-derived endonuclease (VDE) to initiate recombination in meiosis, we show that chromosome structure influences the choice of proteins that resolve recombination intermediates to form <span class="hlt">crossovers</span>. At a Hop1-enriched locus, most VDE-initiated <span class="hlt">crossovers</span>, like most Spo11-initiated <span class="hlt">crossovers</span>, required the meiosis-specific MutLγ resolvase. In contrast, at a locus with lower Hop1 occupancy, most VDE-initiated <span class="hlt">crossovers</span> were MutLγ-independent. In pch2 mutants, the two loci displayed similar Hop1 occupancy levels, and VDE-induced <span class="hlt">crossovers</span> were similarly MutLγ-dependent. We suggest that meiotic and mitotic recombination pathways coexist within meiotic cells, and that features of meiotic chromosome structure determine whether one or the other predominates in different regions. DOI: http://dx.doi.org/10.7554/eLife.19669.001 PMID:27855779</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4637085','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4637085"><span><span class="hlt">Crossover</span> versus Stabilometric Platform for the Treatment of Balance Dysfunction in Parkinson's Disease: A Randomized Study</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Frazzitta, G.; Bossio, F.; Maestri, R.; Palamara, G.; Bera, R.; Ferrazzoli, D.</p> <p>2015-01-01</p> <p>Balance dysfunctions are a major challenge in the treatment of Parkinson's disease (PD). Previous studies have shown that rehabilitation can play a role in their treatment. In this study, we have compared the efficacy of two different devices for balance training: stabilometric platform and <span class="hlt">crossover</span>. We have enrolled 60 PD patients randomly assigned to two groups. The first one (stabilometric group) performed a 4-week cycle of balance training, using the stabilometric platform, whereas the second one (<span class="hlt">crossover</span> group) performed a 4-week cycle of balance training, using the <span class="hlt">crossover</span>. The outcome measures used were Unified Parkinson's Disease Rating Scale (UPDRS) part II, Berg Balance Scale (BBS), Timed Up and Go (TUG), and Six Minutes Walking Test (6MWT). Results showed that TUG, BBS, and UPDRS II improved in both groups. There was not difference in the efficacy of the two balance treatments. Patients in both groups improved also the meters walked in the 6MWT at the end of rehabilitation, but the improvement was better for patients performing <span class="hlt">crossover</span> training. Our results show that the <span class="hlt">crossover</span> and the stabilometric platform have the same effect on balance dysfunction of Parkinsonian patients, while <span class="hlt">crossover</span> gets better results on the walking capacity. PMID:26583142</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25698715','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25698715"><span>Design and analysis of Bayesian adaptive <span class="hlt">crossover</span> trials for evaluating contact lens safety and efficacy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Quan; Toubouti, Youssef; Carlin, Bradley P</p> <p>2017-06-01</p> <p>A <span class="hlt">crossover</span> study, also referred to as a <span class="hlt">crossover</span> trial, is a form of longitudinal study. Subjects are randomly assigned to different arms of the study and receive different treatments sequentially. While there are many frequentist methods to analyze data from a <span class="hlt">crossover</span> study, random effects models for longitudinal data are perhaps most naturally modeled within a Bayesian framework. In this article, we introduce a Bayesian adaptive approach to <span class="hlt">crossover</span> studies for both efficacy and safety endpoints using Gibbs sampling. Using simulation, we find our approach can detect a true difference between two treatments with a specific false-positive rate that we can readily control via the standard equal-tail posterior credible interval. We then illustrate our Bayesian approaches using real data from Johnson & Johnson Vision Care, Inc. contact lens studies. We then design a variety of Bayesian adaptive predictive probability <span class="hlt">crossover</span> studies for single and multiple continuous efficacy endpoints, indicate their extension to binary safety endpoints, and investigate their frequentist operating characteristics via simulation. The Bayesian adaptive approach emerges as a <span class="hlt">crossover</span> trials tool that is useful yet surprisingly overlooked to date, particularly in contact lens development.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18999407','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18999407"><span>Atomic bond fluctuations and <span class="hlt">crossover</span> to potential-energy-landscape-influenced regime in supercooled liquid.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Levashov, V A; Egami, T; Aga, R S; Morris, J R</p> <p>2008-10-01</p> <p>The ideas related to potential-energy landscape and cooperativity of atomic rearrangements are widely discussed in the research field of glass transition. The <span class="hlt">crossover</span> transition from high-temperature regime to potential-energy-landscape-influenced regime was extensively studied using the concept of inherent structure. However, the interpretation of this <span class="hlt">crossover</span> behavior in terms of microscopic changes in real structures is still lacking. In this paper we present several observations on the <span class="hlt">crossover</span> behavior on real structures. We compare fluctuations in the global properties (total number of bonds, total potential energy, pressure) versus fluctuations in the local properties (coordination number, atomic potential energy, local atomic pressure) by means of molecular dynamics simulations. We then show that the total and local fluctuations in the number of atomic bonds in the system depend on temperature differently above and below the temperature of <span class="hlt">crossover</span> to the landscape-influenced regime. Similarly, the ratio between the global and local fluctuations in the potential energy and pressure changes in the vicinity of the <span class="hlt">crossover</span> temperature, whereas the change is less distinct than in the case of the bond fluctuations. Our results indicate that local fluctuations become more correlated below the <span class="hlt">crossover</span> temperature, most likely via the interaction through the dynamic shear elastic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Nanos...8..609H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Nanos...8..609H"><span>Coherent transport through spin-<span class="hlt">crossover</span> magnet Fe2 complexes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Jing; Xie, Rong; Wang, Weiyi; Li, Qunxiang; Yang, Jinlong</p> <p>2015-12-01</p> <p>As one of the most promising building blocks in molecular spintronics, spin <span class="hlt">crossover</span> (SCO) complexes have attracted increasing attention due to their magnetic bistability between the high-spin (HS) and low-spin (LS) states. Here, we explore the electronic structures and transport properties of SCO magnet Fe2 complexes with three different spin-pair configurations, namely [LS-LS], [LS-HS], and [HS-HS], by performing extensive density functional theory calculations combined with the non-equilibrium Green's function technique. Our calculations clearly reveal that the SCO magnet Fe2 complexes should display two-step spin transitions triggered by external stimuli, i.e. temperature or light, which confirm the previous phenomenological model and agree well with previous experimental measurements. Based on the calculated transport results, we observe a nearly perfect spin-filtering effect and negative differential resistance (NDR) behavior integrated in the SCO magnet Fe2 junction with the [HS-HS] configuration. The current through the [HS-HS] SCO magnet Fe2 complex under a small bias voltage is mainly contributed by the spin-down electrons, which is significantly larger than those of the [LS-LS] and [LS-HS] cases. The bias-dependent transmissions are responsible for the observed NDR effect. These theoretical findings suggest that SCO Fe2 complexes hold potential applications in molecular spintronic devices.As one of the most promising building blocks in molecular spintronics, spin <span class="hlt">crossover</span> (SCO) complexes have attracted increasing attention due to their magnetic bistability between the high-spin (HS) and low-spin (LS) states. Here, we explore the electronic structures and transport properties of SCO magnet Fe2 complexes with three different spin-pair configurations, namely [LS-LS], [LS-HS], and [HS-HS], by performing extensive density functional theory calculations combined with the non-equilibrium Green's function technique. Our calculations clearly reveal that the SCO</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4987722','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4987722"><span>Bloodcurdling movies and measures of coagulation: Fear Factor <span class="hlt">crossover</span> trial</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nemeth, Banne; Scheres, Luuk J J; Lijfering, Willem M</p> <p>2015-01-01</p> <p>Objective To assess whether, as has been hypothesised since medieval times, acute fear can curdle blood. Design <span class="hlt">Crossover</span> trial. Setting Main meeting room of Leiden University’s Department of Clinical Epidemiology, the Netherlands, converted to a makeshift cinema. Participants 24 healthy volunteers aged ≤30 years recruited among students, alumni, and employees of the Leiden University Medical Center: 14 were assigned to watch a frightening (horror) movie followed by a non-threatening (educational) movie and 10 to watch the movies in reverse order. The movies were viewed more than a week apart at the same time of day and both lasted approximately 90 minutes. Main outcome measures The primary outcome measures were markers, or “fear factors” of coagulation activity: blood coagulant factor VIII, D-dimer, thrombin-antithrombin complexes, and prothrombin fragments 1+2. The secondary outcome was participant reported fear experienced during each movie using a visual analogue fear scale. Results All participants completed the study. The horror movie was perceived to be more frightening than the educational movie on a visual analogue fear scale (mean difference 5.4, 95% confidence interval 4.7 to 6.1). The difference in factor VIII levels before and after watching the movies was higher for the horror movie than for the educational movie (mean difference of differences 11.1 IU/dL (111 IU/L), 95% confidence interval 1.2 to 21.0 IU/dL). The effect of either movie on levels of thrombin-antithrombin complexes, D-dimer, and prothrombin fragments 1+2 did not differ. Conclusion Frightening (in this case, horror) movies are associated with an increase of blood coagulant factor VIII without actual thrombin formation in young and healthy adults. Trial registration ClinicalTrials.gov NCT02601053. PMID:26673787</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27671366','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27671366"><span>Triggers for Preeclampsia Onset: a Case-<span class="hlt">Crossover</span> Study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ford, Jane B; Schemann, Kathrin; Patterson, Jillian A; Morris, Jonathan; Herbert, Robert D; Roberts, Christine L</p> <p>2016-11-01</p> <p>Risk factors for preeclampsia are well established, whereas, the triggers associated with timing of preeclampsia onset are not. The aim of this study was to establish whether recent infection or other triggers were associated with timing of preeclampsia onset. We used a case-<span class="hlt">crossover</span> design with preeclampsia cases serving as their own controls. Women with singleton pregnancies of ≥20 weeks gestation presenting at three hospitals were eligible for inclusion. Exposures to potential triggers were identified via guided questionnaire. Infective episodes included symptoms lasting >24 h. Preeclampsia was defined as hypertension (BP ≥140 mmHg and/or ≥90 mmHg) and proteinuria (protein/creatinine ratio ≥30 mg/mmol). Conditional logistic regression was used to compare the odds of exposure to potential triggers in the case windows (1-7 days preceding diagnosis of preeclampsia) and control windows (8-14 days prior to diagnosis); unadjusted odds ratios (ORs) are reported. Among 286 recruited women, 25 (8.7%) reported a new infection in the 7 days prior to preeclampsia onset and 21 (7.3%) in the 8-14 days prior. There was no significant association between onset of infection in the 7 days prior and preeclampsia diagnosis (OR 1.24, 95% CI 0.65, 2.34). Consumption of caffeine (OR 0.51, 95% CI 0.33, 0.77), spicy food (OR 0.49, 95% CI 0.30, 0.81), and alcohol (OR 0.26, 95% CI 0.10, 0.71) were strongly inversely associated with preeclampsia onset. Recent infection does not appear to trigger preeclampsia. Decreased consumption of caffeine, spicy food, and alcohol may be prodromal markers. Such behaviours may be early markers of imminent preeclampsia. © 2016 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4732573','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4732573"><span>Clarithromycin in GABA-related Hypersomnolence: A Randomized, <span class="hlt">Crossover</span> Trial</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Trotti, Lynn Marie; Saini, Prabhjyot; Bliwise, Donald L.; Freeman, Amanda A.; Jenkins, Andrew; Rye, David B.</p> <p>2016-01-01</p> <p>Objective Some central hypersomnolence syndromes are associated with a positive allosteric modulator of GABA-A receptors in cerebrospinal fluid. Negative allosteric modulators of GABA-A receptors, including clarithromycin, have been reported to reduce sleepiness in these patients. We sought to systematically assess the effects of clarithromycin on objective vigilance and subjective sleepiness. Methods This was a five-week, randomized, placebo-controlled, double-blind, <span class="hlt">crossover</span> trial of clarithromycin 500 mg with breakfast and lunch, in patients with hypersomnolence syndromes (excluding narcolepsy with cataplexy) and evidence for abnormal cerebrospinal fluid potentiation of GABA-A receptors. The study occurred at a university-affiliated medical center. The primary outcome measure was median reaction time on the psychomotor vigilance task (PVT) at week 2 in each condition. Secondary outcomes included the Epworth Sleepiness Scale, Stanford Sleepiness Scale, Functional Outcomes of Sleep, Pittsburgh Sleep Quality Index, the SF-36, and additional PVT measures. Results Twenty-three patients began treatment. Three patients dropped out, and final analyses were performed on twenty complete cases. Median reaction time was not significantly different between clarithromycin and placebo. Subjective measures of sleepiness were significantly improved on clarithromycin versus placebo. Altered taste perception occurred, but was the only side effect more common on clarithromycin than placebo. No serious adverse events occurred. Interpretation Subjective sleepiness, but not psychomotor vigilance, improved during a two-week course of clarithromycin. Although additional studies are needed, this suggests that clarithromycin may be a reasonable treatment option in patients with treatment-refractory hypersomnolence. This trial was registered at clinicaltrials.gov (NCT01146600) and supported by the American Sleep Medicine Foundation. PMID:26094838</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26673787','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26673787"><span>Bloodcurdling movies and measures of coagulation: Fear Factor <span class="hlt">crossover</span> trial.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nemeth, Banne; Scheres, Luuk J J; Lijfering, Willem M; Rosendaal, Frits R</p> <p>2015-12-16</p> <p>To assess whether, as has been hypothesised since medieval times, acute fear can curdle blood. <span class="hlt">Crossover</span> trial. Main meeting room of Leiden University's Department of Clinical Epidemiology, the Netherlands, converted to a makeshift cinema. 24 healthy volunteers aged ≤30 years recruited among students, alumni, and employees of the Leiden University Medical Center: 14 were assigned to watch a frightening (horror) movie followed by a non-threatening (educational) movie and 10 to watch the movies in reverse order. The movies were viewed more than a week apart at the same time of day and both lasted approximately 90 minutes. The primary outcome measures were markers, or "fear factors" of coagulation activity: blood coagulant factor VIII, D-dimer, thrombin-antithrombin complexes, and prothrombin fragments 1+2. The secondary outcome was participant reported fear experienced during each movie using a visual analogue fear scale. All participants completed the study. The horror movie was perceived to be more frightening than the educational movie on a visual analogue fear scale (mean difference 5.4, 95% confidence interval 4.7 to 6.1). The difference in factor VIII levels before and after watching the movies was higher for the horror movie than for the educational movie (mean difference of differences 11.1 IU/dL (111 IU/L), 95% confidence interval 1.2 to 21.0 IU/dL). The effect of either movie on levels of thrombin-antithrombin complexes, D-dimer, and prothrombin fragments 1+2 did not differ. Frightening (in this case, horror) movies are associated with an increase of blood coagulant factor VIII without actual thrombin formation in young and healthy adults. Trial registration ClinicalTrials.gov NCT02601053. 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20636739','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20636739"><span>Randomised <span class="hlt">cross-over</span> study of oral appliances for snoring.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Maguire, J; Steele, J G; Gibson, G J; Wilson, J A; Steen, N; McCracken, G I</p> <p>2010-06-01</p> <p>To compare a mandibular advancement splint to a control bite raising appliance in the treatment of snoring with or without mild obstructive sleep apnoea syndrome. A prospective two-treatment randomised <span class="hlt">cross-over</span> clinical trial. Single centre secondary care Dental Hospital. Fifty-two subjects (36 men, 16 women) diagnosed with non-apnoeic snoring or mild obstructive sleep apnoea syndrome (apnoea/hypopnoea index < or =15 events/h), were recruited from Departments of Respiratory Medicine and ENT surgery, Newcastle upon Tyne Hospitals NHS Foundation Trust. The Snoring Symptoms Inventory questionnaire (SSI) and the Epworth Sleepiness Score (ESS) were used to evaluate changes in symptoms. Patient reported outcomes (compliance, adverse events, splint preference) were recorded by questionnaire. Subjects attended for five study visits and used a mandibular advancement splint and a bite raising appliance at home each for 4 weeks, with a 3-week washout period between devices. Thirty-eight subjects completed the study. Both the mandibular advancement splint and bite raising appliance significantly reduced the SSI compared to the baseline scores: mandibular advancement splint 5.5, P = 0.013; bite raising appliance 3.1, P = 0.005. No statistically significant difference between the two treatment periods was detected (P > 0.05). The reduction in the Epworth Sleepiness Score was: mandibular advancement splint 1.0, P = 0.02; bite raising appliance 0.3, P = 0.4. The change in the Epworth Sleepiness Score was not statistically significantly different between the mandibular advancement splint and bite raising appliance treatment periods (P > 0.05). In this cohort of patients diagnosed with snoring +/- mild OSA: 1 both the mandibular advancement splint and bite raising appliance designs of splint appeared to reduce the symptoms of snoring; 2 no difference in the magnitude of this effect was detected in favour of one design of splint.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3399742','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3399742"><span>Randomized Polypill <span class="hlt">Crossover</span> Trial in People Aged 50 and Over</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wald, David S.; Morris, Joan K.; Wald, Nicholas J.</p> <p>2012-01-01</p> <p>Background A Polypill is proposed for the primary prevention of cardiovascular disease in people judged to be at risk on account of their age alone. Its efficacy in reducing cholesterol and blood pressure is uncertain. Methods We conducted a randomized double-blind placebo-controlled <span class="hlt">crossover</span> trial of a Polypill among individuals aged 50+ without a history of cardiovascular disease and compared the reductions with those predicted from published estimates of the effects of the individual drugs. Participants took the Polypill (amlodipine 2.5 mg, losartan 25 mg, hydrochlorothiazide 12.5 mg and simvastatin 40 mg) each evening for 12 weeks and a placebo each evening for 12 weeks in random sequence. The mean within-person differences in blood pressure and low density lipoprotein (LDL) cholesterol at the end of each 12 week period were determined. Results 84 out of 86 participants completed both treatment periods. The mean systolic blood pressure was reduced by 17.9 mmHg (95% CI, 15.7–20.1) on the Polypill, diastolic blood pressure by 9.8 mmHg (8.1–11.5), and LDL cholesterol by 1.4 mmol/L (1.2–1.6), reductions of 12%, 11%, and 39% respectively. The results were almost identical to those predicted; 18.4 mmHg, 9.7 mmHg, and 1.4 mmol/L respectively. Conclusion The Polypill resulted in the predicted reductions in blood pressure and LDL cholesterol. Long term reductions of this magnitude would have a substantial effect in preventing heart attacks and strokes. Trial Registration Controlled-Trials.com ISRCTN36672232 PMID:22815989</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15984397','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15984397"><span>Randomized <span class="hlt">crossover</span> comparison of adhesively coupled colostomy pouching systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Berg, Kirsten; Seidler, Heidi</p> <p>2005-03-01</p> <p>Ostomy pouching systems affect well being and quality of life, making selection of the appropriate system a key element of ostomy care. Several innovative adhesively coupled, two-piece systems are on the market. They feature flexible low profiles, allowing pouch removal/replacement without changing the skin barrier or wafer. This facilitates inspection or pouch changes without disrupting peristomal skin. Because few controlled trials compare pouching system effectiveness, a prospective, randomized open-label, <span class="hlt">crossover</span> study was conducted. Under the supervision of ostomy care nurses in six outpatient clinics in Germany, clinical performance of and patient preferences for two adhesively coupled, closed-end pouching systems were compared during normal use. One is a gelatin/pectin-based skin barrier sealed to the pouch with a company-specific adhesive coupling technology (System E); the other, a grooved base plate wafer adhesive pouch coupling system (System F). Seventeen attributes and seven end-of-study measures that included comfort, flexibility, wear time, ease of removal, and overall performance were assessed. Informed, consenting participants were randomly assigned to use one system for five skin barrier/wafer changes or up to 15 days and subsequently switched to the alternative system for a similar period. The 39 participants used a total of 1,645 pouches and 342 skin barriers. All were found safe as determined by incidence and nature of the reported peristomal skin problems, subject withdrawals, and adverse events for both systems. However, System E provided longer pouch wear times (P < 0.01). End-phase ratings favored System E on 10 of the 17 attributes (P < 0.04) and System Fon none. More participants preferred System E on all seven end-of-study measures, five significantly (comfort, flexibility, wear time, ease of removal, and overall performance; (P < 0.02). These participant-reported, ostomy-related outcomes underscore the importance of product evaluation</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19412946','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19412946"><span>Pharmacokinetic-pharmacodynamic <span class="hlt">crossover</span> comparison of two levodopa extension strategies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>LeWitt, Peter A; Jennings, Danna; Lyons, Kelly E; Pahwa, Rajesh; Rabinowicz, Adrian L; Wang, James; Guarnieri, Maria; Hubble, Jean P; Murck, Harold</p> <p>2009-07-15</p> <p>Controlled-release carbidopa and levodopa (CL-CR) and the combination of carbidopa, levodopa, and entacapone (CLE) are used for extending levodopa (L-dopa) effects. In a randomized, open-label <span class="hlt">crossover</span> study of 17 PD subjects with wearing-off responses, we compared 8-hour L-dopa pharmacokinetics (PK) and clinical effects after two doses of CL-CR (50 and 200 mg, respectively) and CLE (37.7, 150, 200 mg, respectively). PK analysis revealed the anticipated near-equivalent mean L-dopa area-under-the-concentration-curve values (639,490 ng min/mL for two doses of CLE, and 662,577 for CL-CR, P = 0.86). The mean hourly fluctuation index for L-dopa concentration was 235% for CLE and 196% for CL-CR (P = 0.004). The mean maximal concentration for the first CLE dose was 1,926 +/- 760 ng/mL and for CL-CR, 1,840 +/- 889 (P = 0.33). During the PK studies, the mean time that L-dopa concentration was > or =1,000 ng/mL for CLE was 291 +/- 88 minutes and for CL-CR, 306 +/- 86 (P = 0.33). The mean percent-time in "off" state was 18% for CLE and 28% for CL-CR (P = 0.017), "on state without dyskinesia" was 64% for CLE and 65% for CL-CR (P = 0.803), and "on state with nontroublesome dyskinesia" was 18% for CLE and 7% for CL-CR (P = 0.03). Despite less "off" time with CLE, both formulations demonstrated similar mean PK values and marked intersubject PK variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8841653','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8841653"><span>Modelling and design of <span class="hlt">cross-over</span> trials.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jones, B; Donev, A N</p> <p>1996-07-15</p> <p>There are many diseases and conditions that can be studied using a <span class="hlt">cross-over</span> clinical trial, where the subjects receive sequences of treatments. The treatments are then compared using the repeated measurements taken 'within' subjects. The actual plan or design of the trial is usually obtained by consulting a published table of designs or by applying relatively simple rules such as using all possible permutations of the treatments. However, there is a danger is this approach because the model assumed for the data when the tables or rules were constructed may not be appropriate for the new trial being planned. Also, there may be restrictions in the new trial on the number of treatment sequences that can be used or on the number of periods of treatment particular subjects can be given. Such restrictions may mean that a published design of the ideal size cannot be found unless compromises are made. A better approach is to make the design satisfy the objectives of the trial rather than vice versa. In this paper we describe an approach to constructing such tailor-made designs which we hope will lead to ill-fitting 'off the peg' designs being a thing of the past. We use a computer algorithm to search for optimal designs and illustrate it using a number of examples. The criterion of optimality used in this paper is A-optimality but our approach is not restricted to one particular criterion. The model used in the search for the optimal design is chosen to suit the nature of the trial at hand and as an example a variety of models for three treatments are considered. We also illustrate the construction of designs for the comparison of two active treatments and a placebo where it can be assumed that the carry-over effects of the active treatments are similar. Finally, we illustrate an augmentation of a design that could arise when the objectives of a trial change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4227630','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4227630"><span>Nutrition intervention for migraine: a randomized <span class="hlt">crossover</span> trial</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2014-01-01</p> <p>Background Limited evidence suggests that dietary interventions may offer a promising approach for migraine. The purpose of this study was to determine the effects of a low-fat plant-based diet intervention on migraine severity and frequency. Methods Forty-two adult migraine sufferers were recruited from the general community in Washington, DC, and divided randomly into two groups. This 36-week <span class="hlt">crossover</span> study included two treatments: dietary instruction and placebo supplement. Each treatment period was 16 weeks, with a 4-week washout between. During the diet period, a low-fat vegan diet was prescribed for 4 weeks, after which an elimination diet was used. Participants were assessed at the beginning, midpoint, and end of each period. Significance was determined using student’s t-tests. Results Worst headache pain in last 2 weeks, as measured by visual analog scale, was initially 6.4/10 cm (SD 2.1 cm), and declined 2.1 cm during the diet period and 0.7 cm during the supplement period (p=0.03). Average headache intensity (0–10 scale) was initially 4.2 (SD 1.4) per week, and this declined by 1.0 during the diet period and by 0.5 during the supplement period (p=0.20). Average headache frequency was initially 2.3 (SD 1.8) per week, and this declined by 0.3 during the diet period and by 0.4 during the supplement period (p=0.61). The Patient’s Global Impression of Change showed greater improvement in pain during the diet period (p<0.001). Conclusions These results suggest that a nutritional approach may be a useful part of migraine treatment, but that methodologic issues necessitate further research. Trial registration Clinicaltrials.gov, NCT01699009 and NCT01547494. PMID:25339342</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22069227','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22069227"><span>Induced quadrupole effects near a <span class="hlt">crossover</span> in a tetragonal TbLiF{sub 4} sheelite in a strong magnetic field up to 50 T</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kazei, Z. A. Snegirev, V. V.; Broto, J.-M.; Abdulsabirov, R. Yu.; Korableva, S. L.</p> <p>2012-12-15</p> <p>The anomalies of magnetic properties of TbLiF{sub 4} caused by the interaction of the energy levels of a rare-earth ion in a strong magnetic field up to 50 T directed along the [100] and [110] axes are studied experimentally and theoretically. The jumps in magnetization M(H) and the maxima of the differential magnetic susceptibility dM(H)/dH are found in critical fields H{sub c} = 28 and 31 T, where the lower component of the excited doublet approaches the ground-state singlet of a Tb{sup 3+} ion. Based on the crystal-field model with known interaction parameters, we calculated the Zeeman effect and the magnetization and magnetic susceptibility curves for the TbLiF{sub 4} crystal, which adequately describe magnetic anomalies and critical parameters of a <span class="hlt">crossover</span>. It is shown that the jumpwise change in the {alpha}- and {gamma}-symmetry quadrupole interactions in TbLiF{sub 4} caused by changes in the corresponding quadrupole moments during the crossing of energy levels leads, in accordance with <span class="hlt">experiments</span>, to a decrease in the critical field H{sub c} by approximately 4 T and an increase in the maximum of the differential susceptibility dM(H)/dH near the <span class="hlt">crossover</span> more than twofold. This behavior can be considered as an analog of the induced quadrupole transition caused by a change of the ground state of the rare-earth ion during <span class="hlt">crossover</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18220283','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18220283"><span><span class="hlt">Cross-over</span>: a generalizable phenomenon necessary for secondary intraneural ganglion cyst formation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Spinner, Robert J; Amrami, Kimberly K; Wang, Huan; Kliot, Michel; Carmichael, Stephen W</p> <p>2008-03-01</p> <p>The appearances of intraneural ganglion cysts are being elucidated. We previously introduced the <span class="hlt">cross-over</span> phenomenon to explain how a fibular (peroneal) or tibial intraneural ganglion cyst arising from the superior tibiofibular joint could give rise to multiple cysts: cyst fluid ascending up the primarily affected nerve could reach the level of the sciatic nerve, fill its common epineurial sheath and spread circumferentially (cross over), at which time pressure fluxes could result in further ascent up the sciatic or descent down the same parent nerve or the opposite, previously unaffected fibular or tibial nerves. In this study, we hypothesized that <span class="hlt">cross-over</span> could occur in other nerves, potentially leading to the formation of more than one intraneural ganglion cyst in such situations. We analyzed the literature and identified a single case that we could review where proximal extension of an intraneural ganglion cyst involving a nerve at a different site could theoretically undergo <span class="hlt">cross-over</span> in another major nerve large enough for available magnetic resonance images to resolve this finding. A case of a suprascapular intraneural ganglion cyst previously reported by our group that arose from the glenohumeral joint and extended to the neck was reanalyzed for the presence or absence of <span class="hlt">cross-over</span>. An injection of dye into the outer epineurium of the suprascapular nerve in a fresh cadaveric specimen was performed to test for <span class="hlt">cross-over</span> experimentally. Retrospective review of this case of suprascapular intraneural ganglion cyst demonstrated evidence to support previously unrecognized <span class="hlt">cross-over</span> at the level of the upper trunk, with predominant ascent up the C5 and the C6 nerve roots and subtle descent down the anterior and posterior divisions of the upper trunk as well as the proximal portion of the suprascapular nerve. This appearance gave rise to multiple interconnected intraneural ganglion cysts arising from a single distant connection to the glenohumeral joint</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012NJPh...14i5008O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012NJPh...14i5008O"><span>Classical to quantum <span class="hlt">crossover</span> of the cyclotron resonance in graphene: a study of the strength of intraband absorption</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Orlita, M.; Crassee, I.; Faugeras, C.; Kuzmenko, A. B.; Fromm, F.; Ostler, M.; Seyller, Th; Martinez, G.; Polini, M.; Potemski, M.</p> <p>2012-09-01</p> <p>We report on absolute magneto-transmission <span class="hlt">experiments</span> on highly doped quasi-free-standing epitaxial graphene targeting the classical-to-quantum <span class="hlt">crossover</span> of the cyclotron resonance. This study allows us to directly extract the carrier density and also other relevant quantities such as the quasiparticle velocity and the Drude weight, which is precisely measured from the strength of the cyclotron resonance. We find that the Drude weight is renormalized with respect to its non-interacting (or random phase approximation) value and that the renormalization is tied to the quasiparticle velocity enhancement. This finding is in agreement with recent theoretical predictions, which attribute the renormalization of the Drude weight in graphene to the interplay between broken Galilean invariance and electron-electron interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/397921','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/397921"><span>One-dimensional analysis of maximum performance in a closed two-phase thermosyphon with a <span class="hlt">crossover</span> flow separator</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lin, L.; Groll, M.; Roesler, S.</p> <p>1996-07-01</p> <p>A comprehensive model is developed to calculate the maximum performance of a thermosyphon with a built-in <span class="hlt">crossover</span> separator. Mechanisms limiting performance are considered to be a flow instability in a natural-circulation two-phase flow system at low reduced pressures (e.g., for Freon-11, p{sub r} < 0.126) and at low total mass flux and wave film spalling at moderate reduced pressures, respectively. Which limit becomes dominant depends on the operating conditions, as shown by the experimental data. In systematic <span class="hlt">experiments</span>, various working fluids are used, viz., water, ethanol, Freon-11, and Freon-113. Operating temperature and liquid fill ratio are varied. The present model for maximum performance agrees well (within {+-} 15%) with experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28249440','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28249440"><span>Microscopic origin of the fragile to strong <span class="hlt">crossover</span> in supercooled water: The role of activated processes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>De Marzio, M; Camisasca, G; Rovere, M; Gallo, P</p> <p>2017-02-28</p> <p>We perform an accurate analysis of the density self-correlation functions of TIP4P/2005 supercooled water on approaching the region of the liquid-liquid critical point. In a previous work on this model, we provided evidence of a fragile to strong <span class="hlt">crossover</span> of the dynamical behavior in the deep supercooled region. The structural relaxation follows the Mode Coupling theory in the fragile region and then deviates from Mode Coupling regime to a strong Arrhenius behavior. This <span class="hlt">crossover</span> is particularly important in water because it is connected to the thermodynamics of the supercooled region. To better understand the origin of this <span class="hlt">crossover</span>, we compute now the Van Hove self-correlation functions. In particular we aim at investigating the presence and the role of the hopping phenomena that are the cause of the fragile to strong <span class="hlt">crossover</span> in simple liquids. In TIP4P/2005 water, we find hopping processes too and we analyze how they depend on temperature and density upon approaching the fragile to strong <span class="hlt">crossover</span> and the Mode Coupling ideal <span class="hlt">crossover</span> temperature. Our results show that water behaves like a simple glass former. After an initial ballistic regime, the cage effect dominates the mild supercooled region, with diffusion taking place at long time. At the fragile to strong <span class="hlt">crossover</span>, we find that hopping (activated) processes start to play a role. This is evidenced by the appearance of peaks in the Van Hove correlation functions. In the deep supercooled regime, our analysis clearly indicates that activated processes dominate the dynamics. The comparison between the Van Hove functions and the radial distribution functions allows to better understand the mechanism of hopping phenomena in supercooled water and to connect their onset directly with the crossing of the Widom Line.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JChPh.146h4502D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JChPh.146h4502D"><span>Microscopic origin of the fragile to strong <span class="hlt">crossover</span> in supercooled water: The role of activated processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Marzio, M.; Camisasca, G.; Rovere, M.; Gallo, P.</p> <p>2017-02-01</p> <p>We perform an accurate analysis of the density self-correlation functions of TIP4P/2005 supercooled water on approaching the region of the liquid-liquid critical point. In a previous work on this model, we provided evidence of a fragile to strong <span class="hlt">crossover</span> of the dynamical behavior in the deep supercooled region. The structural relaxation follows the Mode Coupling theory in the fragile region and then deviates from Mode Coupling regime to a strong Arrhenius behavior. This <span class="hlt">crossover</span> is particularly important in water because it is connected to the thermodynamics of the supercooled region. To better understand the origin of this <span class="hlt">crossover</span>, we compute now the Van Hove self-correlation functions. In particular we aim at investigating the presence and the role of the hopping phenomena that are the cause of the fragile to strong <span class="hlt">crossover</span> in simple liquids. In TIP4P/2005 water, we find hopping processes too and we analyze how they depend on temperature and density upon approaching the fragile to strong <span class="hlt">crossover</span> and the Mode Coupling ideal <span class="hlt">crossover</span> temperature. Our results show that water behaves like a simple glass former. After an initial ballistic regime, the cage effect dominates the mild supercooled region, with diffusion taking place at long time. At the fragile to strong <span class="hlt">crossover</span>, we find that hopping (activated) processes start to play a role. This is evidenced by the appearance of peaks in the Van Hove correlation functions. In the deep supercooled regime, our analysis clearly indicates that activated processes dominate the dynamics. The comparison between the Van Hove functions and the radial distribution functions allows to better understand the mechanism of hopping phenomena in supercooled water and to connect their onset directly with the crossing of the Widom Line.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26699636','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26699636"><span>Maltreatment, Child Welfare, and Recidivism in a Sample of Deep-End <span class="hlt">Crossover</span> Youth.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Baglivio, Michael T; Wolff, Kevin T; Piquero, Alex R; Bilchik, Shay; Jackowski, Katherine; Greenwald, Mark A; Epps, Nathan</p> <p>2016-04-01</p> <p>Although research has oft-documented a maltreatment-delinquency link, the effect of involvement in-and timing of-child welfare system involvement on offending has received less attention. We examine whether the timing of child welfare involvement has differential effects on recidivism of deep-end juvenile offenders (youth who have been adjudicated delinquent by the court and placed in juvenile justice residential programs). The current study uses a large, diverse sample of 12,955 youth completing juvenile justice residential programs between 1 January 2010 and 30 June 2013 in Florida (13 % female, 55 % Black, 11 % Hispanic). Additionally, we explore the direct effects of childhood traumatic events on delinquency, as well as their indirect effects through child welfare involvement using structural equation modeling. The findings indicate that adverse childhood <span class="hlt">experiences</span> fail to exert a direct effect on recidivism, but do exhibit a significant indirect effect on recidivism through child welfare involvement, which is itself associated with recidivism. This means that while having exposures to more types of childhood traumatic events does not, in and of itself, increase the likelihood of re-offending, effects of such <span class="hlt">experiences</span> operate through child welfare placement. Differences in the effects of maltreatment timing and of adverse childhood <span class="hlt">experiences</span> are observed across sex and race/ethnicity subgroups. Across all racial subgroups, exposures to adverse childhood <span class="hlt">experiences</span> have a significant effect on the likelihood of child welfare placement, yet child welfare placement exerts a significant effect on recidivism for White and Hispanic youth, but not for Black youth. Only Hispanic female and White male youth with overlapping child welfare and juvenile justice cases (open cases in both systems at the same time during the study period) were more likely to recidivate than their delinquent-only counterpart youth. <span class="hlt">Crossover</span> status (child welfare and juvenile justice</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24618478','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24618478"><span>Noise levels and cardiovascular mortality: a case-<span class="hlt">crossover</span> analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tobías, A; Recio, A; Díaz, J; Linares, C</p> <p>2015-04-01</p> <p>The relationship between occupational noise and cardiovascular outcomes has been widely investigated. Regarding environmental noise levels, the attention is focused on road traffic noise due to the large number of exposed persons and the large periods of exposure. There are few studies assessing the short-term effects of traffic noise on cardiovascular outcomes. The aim of this study was to quantify the short-term effects of urban noise levels on age-specific cardiovascular mortality. A case-<span class="hlt">crossover</span> design was used. Daily mortality counts in Madrid city due to cardiovascular causes (ICD codes: 390-459) from 1 January 2003 to 31 December 2005 were obtained. Data noise levels were collected as diurnal equivalent noise (Leqd8-22 h), night equivalent noise (Leqn22-8 h), and daily equivalent noise (Leq24 h). Confounding variables as daily levels of air pollutants, temperature, and relative humidity data were controlled. Overdispersed Poisson regression models were adjusted to control for both seasonality and time trends. Estimated effects are reported as percentage increase in the relative risk (IRR) associated with an increase of 1 dBA. The strongest associations between all noise exposure levels and cardiovascular mortality were reported at lag 1: IRR 4.5% (95% CI 0.6, 8.7%), IRR 3.9% (95% CI 0.6, 7.3%), and IRR 6.2% (95% CI 2.1, 10.6%) for Leqd, Leqn, and Leq24, respectively. Analysing by age-specific groups at lag 1, statistically significant associations were found for those aged ≥65: 4.5% (95% CI 0.3, 8.9%), 3.4% (95% CI 0.1, 6.9%), and 6.6% (95% CI 2.2, 11.1%) for Leqd, Leqn, and Leq24, with no substantial changes in the effects of noise exposure levels at lag 1 after adjusting for PM2.5 and NO2. The association found between noise exposure levels and cardiovascular mortality suggests a joint effect of diurnal and night-time noise levels. Our results also reveal independent effects of noise exposure levels and the air pollutants analysed. This strongly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23767547','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23767547"><span>Dimensional <span class="hlt">crossover</span> of hard parallel cylinders confined on cylindrical surfaces.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Martínez-Ratón, Yuri; Velasco, Enrique</p> <p>2013-05-01</p> <p>We derive, from the dimensional-<span class="hlt">crossover</span> criterion, a fundamental-measure density functional for parallel hard curved rectangles moving on a cylindrical surface. We derive it from the density functional of circular arcs of length σ with centers of mass located on an external circumference of radius R(0). The latter functional in turn is obtained from the corresponding two-dimensional functional for a fluid of hard disks of radius R on a flat surface with centers of mass confined onto a circumference of radius R(0). Thus the curved length of closest approach between the two centers of mass of hard disks on this circumference is σ=2R(0)sin(-1)(R/R(0)), the length of the circular arcs. From the density functional of circular arcs, and by applying a dimensional expansion procedure to the spatial dimension orthogonal to the plane of the circumference, we finally obtain the density functional of curved rectangles of edge lengths σ and L. Along with the derivation, we show that, when the centers of mass of the disks are confined to the exterior circumference of a circle of radius R(0),(i) for R(0)>R, the exact Percus one-dimensional (1D) density functional of circular arcs of length 2R(0)sin(-1)(R/R(0)) is obtained, and (ii) for R(0)<R, the zero-dimensional limit (a cavity that can hold one particle at most) is recovered. We also show that, for R(0)>R, the obtained functional is equivalent to that of parallel hard rectangles on a flat surface of the same lengths, except that now the density profile of curved rectangles is a periodic function of the azimuthal angle, ρ(φ,z)=ρ(φ+2π,z). The phase behavior of a fluid of aligned curved rectangles is obtained by calculating the free-energy branches of smectic, columnar, and crystalline phases for different values of the ratio R(0)/R in the range 1<R(0)/R≤4; the smectic phase turns out to be the most stable except for R(0)/R=4, where the crystalline phase becomes reentrant in a small range of packing fractions. When R</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27076992','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27076992"><span>A Randomized <span class="hlt">Crossover</span> Design to Assess Learning Impact and Student Preference for Active and Passive Online Learning Modules.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Prunuske, Amy J; Henn, Lisa; Brearley, Ann M; Prunuske, Jacob</p> <p></p> <p>Medical education increasingly involves online learning <span class="hlt">experiences</span> to facilitate the standardization of curriculum across time and space. In class, delivering material by lecture is less effective at promoting student learning than engaging students in active learning <span class="hlt">experience</span> and it is unclear whether this difference also exists online. We sought to evaluate medical student preferences for online lecture or online active learning formats and the impact of format on short- and long-term learning gains. Students participated online in either lecture or constructivist learning activities in a first year neurologic sciences course at a US medical school. In 2012, students selected which format to complete and in 2013, students were randomly assigned in a <span class="hlt">crossover</span> fashion to the modules. In the first iteration, students strongly preferred the lecture modules and valued being told "what they need to know" rather than figuring it out independently. In the <span class="hlt">crossover</span> iteration, learning gains and knowledge retention were found to be equivalent regardless of format, and students uniformly demonstrated a strong preference for the lecture format, which also on average took less time to complete. When given a choice for online modules, students prefer passive lecture rather than completing constructivist activities, and in the time-limited environment of medical school, this choice results in similar performance on multiple-choice examinations with less time invested. Instructors need to look more carefully at whether assessments and learning strategies are helping students to obtain self-directed learning skills and to consider strategies to help students learn to value active learning in an online environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MSSP...83..272J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MSSP...83..272J"><span>Study on nature of <span class="hlt">crossover</span> phenomena with application to gearbox fault diagnosis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiang, Xingxing; Li, Shunming; Wang, Yong</p> <p>2017-01-01</p> <p>Detrended Fluctuation Analysis (DFA) is a robust tool for uncovering long-range correlations hidden in the non-stationary data. Recently, <span class="hlt">crossover</span> properties of the scaling-law curve obtained by DFA have been applied to diagnose gearbox faults. However, the nature of the <span class="hlt">crossover</span> phenomena has not been well- explained. In this paper, an explanation for the nature of <span class="hlt">crossover</span> phenomena is specifically given, which is conducive to discovering novel features for gearbox fault diagnosis. Firstly, an explicit exposition of the <span class="hlt">crossover</span> phenomena is provided by analyzing the gearbox vibration signal. Secondly, the nature of <span class="hlt">crossover</span> phenomena is specifically disclosed. Thirdly, the features with clear physical meaning are proposed to describe operating conditions of a gearbox. Then, to overcome the deficiency of feature extraction through visual observation, a piecewise-linear regression model is utilized to extract the features automatically. Lastly, several combinations of these features are used to classify the fault types. As a consequence, the proposed novel features are verified that they can well- distinguish the gearbox operating conditions with different fault types and severities, and deliver a better performance than the existing method depending on the sensitive index (SI).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JaJAP..55fGL04M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JaJAP..55fGL04M"><span>Constructing higher order DNA origami arrays using DNA junctions of anti-parallel/parallel double <span class="hlt">crossovers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ma, Zhipeng; Park, Seongsu; Yamashita, Naoki; Kawai, Kentaro; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu</p> <p>2016-06-01</p> <p>DNA origami provides a versatile method for the construction of nanostructures with defined shape, size and other properties; such nanostructures may enable a hierarchical assembly of large scale architecture for the placement of other nanomaterials with atomic precision. However, the effective use of these higher order structures as functional components depends on knowledge of their assembly behavior and mechanical properties. This paper demonstrates construction of higher order DNA origami arrays with controlled orientations based on the formation of two types of DNA junctions: anti-parallel and parallel double <span class="hlt">crossovers</span>. A two-step assembly process, in which preformed rectangular DNA origami monomer structures themselves undergo further self-assembly to form numerically unlimited arrays, was investigated to reveal the influences of assembly parameters. AFM observations showed that when parallel double <span class="hlt">crossover</span> DNA junctions are used, the assembly of DNA origami arrays occurs with fewer monomers than for structures formed using anti-parallel double <span class="hlt">crossovers</span>, given the same assembly parameters, indicating that the configuration of parallel double <span class="hlt">crossovers</span> is not energetically preferred. However, the direct measurement by AFM force-controlled mapping shows that both DNA junctions of anti-parallel and parallel double <span class="hlt">crossovers</span> have homogeneous mechanical stability with any part of DNA origami.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JPhA...42s5001G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JPhA...42s5001G"><span>The <span class="hlt">crossover</span> between organized and disorganized states in some non-equilibrium systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>González, Diego Luis; Téllez, Gabriel</p> <p>2009-05-01</p> <p>We study numerically the <span class="hlt">crossover</span> between organized and disorganized states of three non-equilibrium systems: the Poisson/coalesce random walk (PCRW), a one-dimensional spin system and a quasi one-dimensional lattice gas. In all cases, we describe this <span class="hlt">crossover</span> in terms of the average spacing between particles/domain borders langS(t)rang and the spacing distribution functions p(n)(s). The nature of the <span class="hlt">crossover</span> is not the same for all systems; however, we found that for all systems the nearest neighbor distribution p(0)(s) is well fitted by the Berry-Robnik model. The destruction of the level repulsion in the <span class="hlt">crossover</span> between organized and disorganized states is present in all systems. Additionally, we found that the correlations between domains in the gas and spin systems are not strong and can be neglected in a first approximation, but for the PCRW the correlations between particles must be taken into account. To find p(n)(s) with n > 1, we propose two different analytical models based on the Berry-Robnik model. Our models give us a good approximation for the statistical behavior of these systems at their <span class="hlt">crossover</span> and allow us to quantify the degree of order/disorder of the system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPA....7f5304Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPA....7f5304Y"><span>Dimensional analysis and prediction of dielectrophoretic <span class="hlt">crossover</span> frequency of spherical particles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yeh, Che-Kai; Juang, Jia-Yang</p> <p>2017-06-01</p> <p>The manipulation of biological cells and micrometer-scale particles using dielectrophoresis (DEP) is an indispensable technique for lab-on-a-chip systems for many biological and colloidal science applications. However, existing models, including the dipole model and numerical simulations based on Maxwell stress tensor (MST), cannot achieve high accuracy and high computation efficiency at the same time. The dipole model is widely used and provides adequate predictions on the <span class="hlt">crossover</span> frequency of submicron particles, but cannot predict the <span class="hlt">crossover</span> frequency for larger particles accurately; on the other hand, the MST method offers high accuracy for a wide variety of particle sizes and shapes, but is time-consuming and may lack predictive understanding of the interplay between key parameters. Here we present a mathematical model, using dimensional analysis and the Buckingham pi theorem, that permits high accuracy and efficiency in predicting the <span class="hlt">crossover</span> frequency of spherical particles. The curve fitting and calculation are performed using commercial packages OriginLab and MATLAB, respectively. In addition, through this model we also can predict the conditions in which no <span class="hlt">crossover</span> frequency exists. Also, we propose a pair of dimensionless parameters, forming a functional relation, that provide physical insights into the dependency of the <span class="hlt">crossover</span> frequency on five key parameters. The model is verified under several scenarios using comprehensive MST simulations by COMSOL Multiphysics software (COMSOL, Inc.) and some published experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24289144','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24289144"><span>Bayesian analysis of time-series data under case-<span class="hlt">crossover</span> designs: posterior equivalence and inference.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Shi; Mukherjee, Bhramar; Batterman, Stuart; Ghosh, Malay</p> <p>2013-12-01</p> <p>Case-<span class="hlt">crossover</span> designs are widely used to study short-term exposure effects on the risk of acute adverse health events. While the frequentist literature on this topic is vast, there is no Bayesian work in this general area. The contribution of this paper is twofold. First, the paper establishes Bayesian equivalence results that require characterization of the set of priors under which the posterior distributions of the risk ratio parameters based on a case-<span class="hlt">crossover</span> and time-series analysis are identical. Second, the paper studies inferential issues under case-<span class="hlt">crossover</span> designs in a Bayesian framework. Traditionally, a conditional logistic regression is used for inference on risk-ratio parameters in case-<span class="hlt">crossover</span> studies. We consider instead a more general full likelihood-based approach which makes less restrictive assumptions on the risk functions. Formulation of a full likelihood leads to growth in the number of parameters proportional to the sample size. We propose a semi-parametric Bayesian approach using a Dirichlet process prior to handle the random nuisance parameters that appear in a full likelihood formulation. We carry out a simulation study to compare the Bayesian methods based on full and conditional likelihood with the standard frequentist approaches for case-<span class="hlt">crossover</span> and time-series analysis. The proposed methods are illustrated through the Detroit Asthma Morbidity, Air Quality and Traffic study, which examines the association between acute asthma risk and ambient air pollutant concentrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15987698','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15987698"><span>Factors influencing recombination frequency and distribution in a human meiotic <span class="hlt">crossover</span> hotspot.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jeffreys, Alec J; Neumann, Rita</p> <p>2005-08-01</p> <p>Little is known about the factors that influence the frequency and distribution of meiotic recombination events within human <span class="hlt">crossover</span> hotspots. We now describe the detailed analysis of sperm recombination in the NID1 hotspot. Like the neighbouring MS32 hotspot, the NID1 hotspot is associated with a minisatellite, suggesting that hotspots predispose DNA to tandem repetition. Unlike MS32, <span class="hlt">crossover</span> resolution breakpoints in NID1 avoid the minisatellite, producing a cold spot within the hotspot. This avoidance may be related to the palindromic nature of the minisatellite interfering with the generation and/or processing of recombination intermediates. The NID1 hotspot also contains a single nucleotide polymorphism (SNP) close to the centre, which appears to directly influence the frequency of <span class="hlt">crossover</span> initiation. Quantitative gene conversion assays show that this SNP affects the frequency of gene conversion and <span class="hlt">crossover</span> to a very similar extent, providing evidence that conversions and <span class="hlt">crossovers</span> are triggered by the same recombination initiating events. The recombination-suppressing allele is over-transmitted to recombinant progeny, and provides the most dramatic example to date of recombination-mediated meiotic drive, of a magnitude sufficient to virtually guarantee that the recombination suppressor will eventually replace the more active allele in human populations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3945165','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3945165"><span>Randomized <span class="hlt">crossover</span> clinical trial of real and sham peripheral prism glasses for hemianopia</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bowers, Alex R.; Keeney, Karen; Peli, Eli</p> <p>2013-01-01</p> <p>Objective To evaluate the efficacy of real relative to sham peripheral prism glasses for patients with complete homonymous hemianopia and without visual neglect. Methods Patients recruited at 13 clinics were allocated by minimization into a double-masked, <span class="hlt">crossover</span> trial with two groups. One group received real (57Δ) oblique and sham (≤ 5Δ) horizontal prisms; the other received real horizontal and sham oblique, in counterbalanced order. A masked data collector at each clinic administered questionnaires after each 4-week <span class="hlt">crossover</span> period. Main outcome measure The primary outcome was the overall difference, across the two periods of the <span class="hlt">crossover</span>, between the proportion of participants who wanted to continue with (said “yes” to) real prisms and the proportion who said yes to sham prisms. The secondary outcome was the difference in perceived mobility improvement between real and sham prisms. Results Of 73 patients randomized, 61 completed the <span class="hlt">crossover</span>. A significantly higher proportion said yes to real than sham prisms (64% vs. 36%; odds ratio 5.3, 95% CI 1.8 to 21.0). Participants who continued wear after 6 months reported greater improvement in mobility with real than sham prisms at <span class="hlt">crossover</span> end (p=0.002); participants who discontinued wear reported no difference. Conclusion Real peripheral prism glasses were more helpful for obstacle avoidance when walking than sham glasses, with no differences between the horizontal and oblique designs. Applications to clinical practice Peripheral prism glasses provide a simple and inexpensive mobility rehabilitation intervention for hemianopia. PMID:24201760</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1172274','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1172274"><span>Hydrophobic hydration from small to large lengthscales: Understanding and manipulating the <span class="hlt">crossover</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rajamani, Sowmianarayanan; Truskett, Thomas M.; Garde, Shekhar</p> <p>2005-01-01</p> <p>Small and large hydrophobic solutes exhibit remarkably different hydration thermodynamics. Small solutes are accommodated in water with minor perturbations to water structure, and their hydration is captured accurately by theories that describe density fluctuations in pure water. In contrast, hydration of large solutes is accompanied by dewetting of their surfaces and requires a macroscopic thermodynamic description. A unified theoretical description of these lengthscale dependencies was presented by Lum, Chandler, and Weeks [(1999) J. Phys. Chem. B 103, 4570–4577]. Here, we use molecular simulations to study lengthscale-dependent hydrophobic hydration under various thermodynamic conditions. We show that the hydration of small and large solutes displays disparate dependencies on thermodynamic variables, including pressure, temperature, and additive concentration. Understanding these dependencies allows manipulation of the small-to-large <span class="hlt">crossover</span> lengthscale, which is nanoscopic under ambient conditions. Specifically, applying hydrostatic tension or adding ethanol decreases the <span class="hlt">crossover</span> length to molecular sizes, making it accessible to atomistic simulations. With detailed temperature-dependent studies, we further demonstrate that hydration thermodynamics changes gradually from entropic to enthalpic near the <span class="hlt">crossover</span>. The nanoscopic lengthscale of the <span class="hlt">crossover</span> and its sensitivity to thermodynamic variables imply that quantitative modeling of biomolecular self-assembly in aqueous solutions requires elements of both molecular and macroscopic hydration physics. We also show that the small-to-large <span class="hlt">crossover</span> is directly related to the Egelstaff-Widom lengthscale, the product of surface tension and isothermal compressibility, which is another fundamental lengthscale in liquids. PMID:15972804</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15972804','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15972804"><span>Hydrophobic hydration from small to large lengthscales: Understanding and manipulating the <span class="hlt">crossover</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rajamani, Sowmianarayanan; Truskett, Thomas M; Garde, Shekhar</p> <p>2005-07-05</p> <p>Small and large hydrophobic solutes exhibit remarkably different hydration thermodynamics. Small solutes are accommodated in water with minor perturbations to water structure, and their hydration is captured accurately by theories that describe density fluctuations in pure water. In contrast, hydration of large solutes is accompanied by dewetting of their surfaces and requires a macroscopic thermodynamic description. A unified theoretical description of these lengthscale dependencies was presented by Lum, Chandler, and Weeks [(1999) J. Phys. Chem. B 103, 4570-4577]. Here, we use molecular simulations to study lengthscale-dependent hydrophobic hydration under various thermodynamic conditions. We show that the hydration of small and large solutes displays disparate dependencies on thermodynamic variables, including pressure, temperature, and additive concentration. Understanding these dependencies allows manipulation of the small-to-large <span class="hlt">crossover</span> lengthscale, which is nanoscopic under ambient conditions. Specifically, applying hydrostatic tension or adding ethanol decreases the <span class="hlt">crossover</span> length to molecular sizes, making it accessible to atomistic simulations. With detailed temperature-dependent studies, we further demonstrate that hydration thermodynamics changes gradually from entropic to enthalpic near the <span class="hlt">crossover</span>. The nanoscopic lengthscale of the <span class="hlt">crossover</span> and its sensitivity to thermodynamic variables imply that quantitative modeling of biomolecular self-assembly in aqueous solutions requires elements of both molecular and macroscopic hydration physics. We also show that the small-to-large <span class="hlt">crossover</span> is directly related to the Egelstaff-Widom lengthscale, the product of surface tension and isothermal compressibility, which is another fundamental lengthscale in liquids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24510584','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24510584"><span>Two measures of bilingualism in the memories of immigrants and indigenous minorities: <span class="hlt">crossover</span> memories and codeswitching.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Altman, Carmit</p> <p>2015-04-01</p> <p>Two indices of bilingualism, <span class="hlt">crossover</span> memories and codeswitching (CS), were explored in five groups of immigrant (English-Hebrew, Georgian-Hebrew Russian-Hebrew) and indigenous bilinguals (Arabic-Hebrew, Hebrew-English). Participants recalled memories in response to cue words and then were asked to report the language of retrieval and provide a more elaborate narrative. More memories were 'same language' memories, recalled in the language of the experimental session/cue word, but as many as 48 % of the memories were <span class="hlt">crossovers</span>, i.e. memories reported in a language other than the language of the session/cue word. In an effort to examine the ecological validity of the self-reported language of the memories, the frequency of CS in the elaborated narratives was investigated. For the entire sample, more CS was found for self-reported <span class="hlt">crossover</span> memories in L2 sessions. In a further analysis of CS in <span class="hlt">crossover</span> memories, collapsed across L1 and L2 sessions, significant differences emerged between immigrants and indigenous bilinguals. Differences between immigrant and non-immigrant bilinguals are discussed in terms of the role of activation in <span class="hlt">crossover</span> memories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NatCo...4E2826L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NatCo...4E2826L"><span>A light-induced spin <span class="hlt">crossover</span> actuated single-chain magnet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Tao; Zheng, Hui; Kang, Soonchul; Shiota, Yoshihito; Hayami, Shinya; Mito, Masaki; Sato, Osamu; Yoshizawa, Kazunari; Kanegawa, Shinji; Duan, Chunying</p> <p>2013-11-01</p> <p>Both spin-<span class="hlt">crossover</span> complexes and molecular nanomagnets display bistable magnetic states, potentially behaving as elementary binary units for information storage. It is a challenge to introduce spin-<span class="hlt">crossover</span> units into molecular nanomagnets to switch the bistable state of the nanomagnets through external stimuli-tuned spin <span class="hlt">crossover</span>. Here we report an iron(II) spin-<span class="hlt">crossover</span> unit and paramagnetic iron(III) ions that are incorporated into a well-isolated double-zigzag chain. The chain exhibits thermally induced reversible spin-<span class="hlt">crossover</span> and light-induced excited spin-state trapping at the iron(II) sites. Single-chain magnet behaviour is actuated accompanying the synergy between light-induced excited spin-state trapping at the iron(II) sites and ferromagnetic interactions between the photoinduced high-spin iron(II) and low-spin iron(III) ions in the chain. The result provides a strategy to switch the bistable state of molecular nanomagnets using external stimuli such as light and heat, with the potential to erase and write information at a molecular level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16705162','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16705162"><span>Sgs1 regulates gene conversion tract lengths and <span class="hlt">crossovers</span> independently of its helicase activity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lo, Yi-Chen; Paffett, Kimberly S; Amit, Or; Clikeman, Jennifer A; Sterk, Rosa; Brenneman, Mark A; Nickoloff, Jac A</p> <p>2006-06-01</p> <p>RecQ helicases maintain genome stability and suppress tumors in higher eukaryotes through roles in replication and DNA repair. The yeast RecQ homolog Sgs1 interacts with Top3 topoisomerase and Rmi1. In vitro, Sgs1 binds to and branch migrates Holliday junctions (HJs) and the human RecQ homolog BLM, with Top3alpha, resolves synthetic double HJs in a noncrossover sense. Sgs1 suppresses <span class="hlt">crossovers</span> during the homologous recombination (HR) repair of DNA double-strand breaks (DSBs). <span class="hlt">Crossovers</span> are associated with long gene conversion tracts, suggesting a model in which Sgs1 helicase catalyzes reverse branch migration and convergence of double HJs for noncrossover resolution by Top3. Consistent with this model, we show that allelic <span class="hlt">crossovers</span> and gene conversion tract lengths are increased in sgs1Delta. However, <span class="hlt">crossover</span> and tract length suppression was independent of Sgs1 helicase activity, which argues against helicase-dependent HJ convergence. HJs may converge passively by a "random walk," and Sgs1 may play a structural role in stimulating Top3-dependent resolution. In addition to the new helicase-independent functions for Sgs1 in <span class="hlt">crossover</span> and tract length control, we define three new helicase-dependent functions, including the suppression of chromosome loss, chromosome missegregation, and synthetic lethality in srs2Delta. We propose that Sgs1 has helicase-dependent functions in replication and helicase-independent functions in DSB repair by HR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JChPh.141u4703Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JChPh.141u4703Z"><span>Predicting critical temperatures of iron(II) spin <span class="hlt">crossover</span> materials: Density functional theory plus U approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Yachao</p> <p>2014-12-01</p> <p>A first-principles study of critical temperatures (Tc) of spin <span class="hlt">crossover</span> (SCO) materials requires accurate description of the strongly correlated 3d electrons as well as much computational effort. This task is still a challenge for the widely used local density or generalized gradient approximations (LDA/GGA) and hybrid functionals. One remedy, termed density functional theory plus U (DFT+U) approach, introduces a Hubbard U term to deal with the localized electrons at marginal computational cost, while treats the delocalized electrons with LDA/GGA. Here, we employ the DFT+U approach to investigate the Tc of a pair of iron(II) SCO molecular crystals (α and β phase), where identical constituent molecules are packed in different ways. We first calculate the adiabatic high spin-low spin energy splitting ΔEHL and molecular vibrational frequencies in both spin states, then obtain the temperature dependent enthalpy and entropy changes (ΔH and ΔS), and finally extract Tc by exploiting the ΔH/T - T and ΔS - T relationships. The results are in agreement with <span class="hlt">experiment</span>. Analysis of geometries and electronic structures shows that the local ligand field in the α phase is slightly weakened by the H-bondings involving the ligand atoms and the specific crystal packing style. We find that this effect is largely responsible for the difference in Tc of the two phases. This study shows the applicability of the DFT+U approach for predicting Tc of SCO materials, and provides a clear insight into the subtle influence of the crystal packing effects on SCO behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26093936','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26093936"><span>Cytopathology whole slide images and adaptive tutorials for postgraduate pathology trainees: a randomized <span class="hlt">crossover</span> trial.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Van Es, Simone L; Kumar, Rakesh K; Pryor, Wendy M; Salisbury, Elizabeth L; Velan, Gary M</p> <p>2015-09-01</p> <p>To determine whether cytopathology whole slide images and virtual microscopy adaptive tutorials aid learning by postgraduate trainees, we designed a randomized <span class="hlt">crossover</span> trial to evaluate the quantitative and qualitative impact of whole slide images and virtual microscopy adaptive tutorials compared with traditional glass slide and textbook methods of learning cytopathology. Forty-three anatomical pathology registrars were recruited from Australia, New Zealand, and Malaysia. Online assessments were used to determine efficacy, whereas user <span class="hlt">experience</span> and perceptions of efficiency were evaluated using online Likert scales and open-ended questions. Outcomes of online assessments indicated that, with respect to performance, learning with whole slide images and virtual microscopy adaptive tutorials was equivalent to using traditional methods. High-impact learning, efficiency, and equity of learning from virtual microscopy adaptive tutorials were strong themes identified in open-ended responses. Participants raised concern about the lack of z-axis capability in the cytopathology whole slide images, suggesting that delivery of z-stacked whole slide images online may be important for future educational development. In this trial, learning cytopathology with whole slide images and virtual microscopy adaptive tutorials was found to be as effective as and perceived as more efficient than learning from glass slides and textbooks. The use of whole slide images and virtual microscopy adaptive tutorials has the potential to provide equitable access to effective learning from teaching material of consistently high quality. It also has broader implications for continuing professional development and maintenance of competence and quality assurance in specialist practice. Copyright © 2015 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27161198','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27161198"><span>Guest-, Light- and Thermally-Modulated Spin <span class="hlt">Crossover</span> in [Fe(II) 2 ] Supramolecular Helicates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Darawsheh, Mohanad; Barrios, Leoni A; Roubeau, Olivier; Teat, Simon J; Aromí, Guillem</p> <p>2016-06-13</p> <p>A new bis(pyrazolylpyridine) ligand (H2 L) has been prepared to form functional [Fe2 (H2 L)3 ](4+) metallohelicates. Changes to the synthesis yield six derivatives, X@[Fe2 (H2 L)3 ]X(PF6 )2 ⋅xCH3 OH (1, x=5.7 and X=Cl; 2, x=4 and X=Br), X@[Fe2 (H2 L)3 ]X(PF6 )2 ⋅yCH3 OH⋅H2 O (1 a, y=3 and X=Cl; 2 a, y=1 and X=Br) and X@[Fe2 (H2 L)3 ](I3 )2 ⋅3 Et2 O (1 b, X=Cl; 2 b, X=Br). Their structure and functional properties are described in detail by single-crystal X-ray diffraction <span class="hlt">experiments</span> at several temperatures. Helicates 1 a and 2 a are obtained from 1 and 2, respectively, by a single-crystal-to-single-crystal mechanism. The three possible magnetic states, [LS-LS], [LS-HS], and [HS-HS] can be accessed over large temperature ranges as a result of the structural nonequivalence of the Fe(II) centers. The nature of the guest (Cl(-) vs. Br(-) ) shifts the spin <span class="hlt">crossover</span> (SCO) temperature by roughly 40 K. Also, metastable [LS-HS] or [HS-HS] states are generated through irradiation. All helicates (X@[Fe2 (H2 L)3 ])(3+) persist in solution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/924710','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/924710"><span><span class="hlt">Crossover</span> from capillary fingering to compact invasion for two-phase drainage with stable viscosity ratios</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ferer, M.V.; Bromhal, G.S.; Smith, D.H</p> <p>2007-02-01</p> <p>Motivated by a wide range of applications from enhanced oil recovery to carbon dioxide sequestration, we have developed a two-dimensional, pore-level model of immiscible drainage, incorporating viscous, capillary, and gravitational effects. This model has been validated quantitatively, in the very different limits of zero viscosity ratio and zero capillary number; flow patterns from modeling agree well with <span class="hlt">experiment</span>. For a range of stable viscosity ratios (μinjected/μdisplaced 1), we have increased the capillary number, Nc, and studied the way in which the flows deviate from capillary fingering (the fractal flow of invasion percolation) and become compact for realistic capillary numbers. Results exhibiting this <span class="hlt">crossover</span> from capillary fingering to compact invasion are presented for the average position of the injected fluid, the fluid–fluid interface, the saturation and fractional flow profiles, and the relative permeabilities. The agreement between our results and earlier theoretical predictions [Blunt M, King MJ, Scher H. Simulation and theory of two-phase flow in porous media. Phys Rev A 1992;46:7680–99; Lenormand R. Flow through porous media: limits of fractal patterns. Proc Roy Soc A 1989;423:159–68; Wilkinson D. Percolation effects in immiscible displacement. Phys Rev A 1986;34:1380–90; Xu B, Yortsos YC, Salin D. Invasion Percolation with viscous forces. Phys Rev E 1998;57:739–51] supports the validity of these general theoretical arguments, which were independent of the details of the porous media in both two and three dimensions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22413277','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22413277"><span>Predicting critical temperatures of iron(II) spin <span class="hlt">crossover</span> materials: Density functional theory plus U approach</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhang, Yachao</p> <p>2014-12-07</p> <p>A first-principles study of critical temperatures (T{sub c}) of spin <span class="hlt">crossover</span> (SCO) materials requires accurate description of the strongly correlated 3d electrons as well as much computational effort. This task is still a challenge for the widely used local density or generalized gradient approximations (LDA/GGA) and hybrid functionals. One remedy, termed density functional theory plus U (DFT+U) approach, introduces a Hubbard U term to deal with the localized electrons at marginal computational cost, while treats the delocalized electrons with LDA/GGA. Here, we employ the DFT+U approach to investigate the T{sub c} of a pair of iron(II) SCO molecular crystals (α and β phase), where identical constituent molecules are packed in different ways. We first calculate the adiabatic high spin-low spin energy splitting ΔE{sub HL} and molecular vibrational frequencies in both spin states, then obtain the temperature dependent enthalpy and entropy changes (ΔH and ΔS), and finally extract T{sub c} by exploiting the ΔH/T − T and ΔS − T relationships. The results are in agreement with <span class="hlt">experiment</span>. Analysis of geometries and electronic structures shows that the local ligand field in the α phase is slightly weakened by the H-bondings involving the ligand atoms and the specific crystal packing style. We find that this effect is largely responsible for the difference in T{sub c} of the two phases. This study shows the applicability of the DFT+U approach for predicting T{sub c} of SCO materials, and provides a clear insight into the subtle influence of the crystal packing effects on SCO behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27816077','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27816077"><span>Relevant and Irrelevant Fear in Flooding - A <span class="hlt">Crossover</span> Study of Phobic Patients - Republished Article.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Watson, J P; Marks, I M</p> <p>2016-09-01</p> <p>This study investigated the role of relevant vs irrelevant fear cues in the flooding of phobic patients. Six specific phobics and 10 agoraphobics were treated in a balanced <span class="hlt">crossover</span> design. Eight patients had eight sessions of imaginal flooding concerned with their phobias followed by eight imaginal sessions concerned with situations which are normally frightening to anybody. Another eight patients had the same two treatments in the reverse order. The combined effects of both treatments after 16 sessions resulted in significant improvement on clinical, attitudinal, and heart-rate measures. Improvement was maintained at six months follow-up. Eight sessions by each treatment alone also produced significant improvement on clinical and attitudinal measures. Irrelevant fear also produced significant improvement in heart-rate and skin-conductance measures. The two treatments did not differ significantly from each other in their effects, except that irrelevant fear produced significantly more improvement than did relevant flooding in subjective anxiety during phobic imagery. The two treatments had significantly different prognostic correlates. Heightened physiological activity at the start of treatment predicted a good outcome to relevant flooding but not to irrelevant fear. High subjective anxiety during imagery before treatment predicted poor outcome to irrelevant fear. High anxiety during treatment sessions predicted good outcome to irrelevant fear, but did not correlate with outcome to relevant flooding. The <span class="hlt">experience</span> of relevant and irrelevant fear in fantasy reduced phobic anxiety and avoidance to a similar extent, but appeared to do so through different mechanisms. These mechanisms need not be mutually exclusive and might be additive.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28526482','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28526482"><span>Reducing Trunk Compensation in Stroke Survivors: A Randomized <span class="hlt">Crossover</span> Trial Comparing Visual and Force Feedback Modalities.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Valdés, Bulmaro Adolfo; Schneider, Andrea Nicole; Van der Loos, H F Machiel</p> <p>2017-10-01</p> <p>To investigate whether the compensatory trunk movements of stroke survivors observed during reaching tasks can be decreased by force and visual feedback, and to examine whether one of these feedback modalities is more efficacious than the other in reducing this compensatory tendency. Randomized <span class="hlt">crossover</span> trial. University research laboratory. Community-dwelling older adults (N=15; 5 women; mean age, 64±11y) with hemiplegia from nontraumatic hemorrhagic or ischemic stroke (>3mo poststroke), recruited from stroke recovery groups, the research group's website, and the community. In a single session, participants received augmented feedback about their trunk compensation during a bimanual reaching task. Visual feedback (60 trials) was delivered through a computer monitor, and force feedback (60 trials) was delivered through 2 robotic devices. Primary outcome measure included change in anterior trunk displacement measured by motion tracking camera. Secondary outcomes included trunk rotation, index of curvature (measure of straightness of hands' path toward target), root mean square error of hands' movement (differences between hand position on every iteration of the program), completion time for each trial, and posttest questionnaire to evaluate users' <span class="hlt">experience</span> and system's usability. Both visual (-45.6% [45.8 SD] change from baseline, P=.004) and force (-41.1% [46.1 SD], P=.004) feedback were effective in reducing trunk compensation. Scores on secondary outcome measures did not improve with either feedback modality. Neither feedback condition was superior. Visual and force feedback show promise as 2 modalities that could be used to decrease trunk compensation in stroke survivors during reaching tasks. It remains to be established which one of these 2 feedback modalities is more efficacious than the other as a cue to reduce compensatory trunk movement. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28045559','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28045559"><span>Acute blood pressure response in hypertensive elderly women immediately after water aerobics exercise: A <span class="hlt">crossover</span> study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cunha, Raphael Martins; Vilaça-Alves, José; Noleto, Marcelo Vasconcelos; Silva, Juliana Sá; Costa, Andressa Moura; Silva, Christoffer Novais Farias; Póvoa, Thaís Inácio Rolim; Lehnen, Alexandre Machado</p> <p>2017-01-01</p> <p>Water aerobics exercise is widely recommended for elderly people. However, little is known about the acute effects on hemodynamic variables. Thus, we assessed the effects of a water aerobic session on blood pressure in hypertensive elderly women. Fifty hypertensive elderly women aged 67.8 ± 4.1 years, 1.5 ± 0.6 m high and BMI 28.6 ± 3.9 kg/m(2), participated in a <span class="hlt">crossover</span> clinical trial. The <span class="hlt">experiment</span> consisted of a 45-minute water aerobics session (70%-75% HRmax adjusted for the aquatic environment) (ES) and a control session (no exercise for 45 minutes) (CS). Heart rate was monitored using a heart rate monitor and systolic blood pressure (SBP) and diastolic (DBP) measurements were taken using a semi-automatic monitor before and immediately after the sessions, and at 10, 20 and 30 minutes thereafter. It was using a generalized estimating equation (GEE) with Bonferroni's post-hoc test (p < 0.05). At the end of the experimental session, ES showed a rise in SBP of 17.4 mmHg (14.3%, p < 0.001) and DBP of 5.4 mmHg (7.8%, p < 0.001) compared to CS. At 10 minutes after exercise, BP declined in ES by a greater magnitude than in CS (SBP 7.5 mmHg, 6.2%, p = 0.005 and DBP 3.8 mmHg, 5.5%, p = 0.013). At 20 minutes after exercise and thereafter, SBP and DBP were similar in both ES and CS. In conclusion, BP returned to control levels within 10-20 minutes remaining unchanged until 30 minutes after exercise, and post-exercise hypotension was not observed. Besides, BP changed after exercise was a safe rise of small magnitude for hypertensive people.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25481157','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25481157"><span>Predicting critical temperatures of iron(II) spin <span class="hlt">crossover</span> materials: density functional theory plus U approach.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Yachao</p> <p>2014-12-07</p> <p>A first-principles study of critical temperatures (T(c)) of spin <span class="hlt">crossover</span> (SCO) materials requires accurate description of the strongly correlated 3d electrons as well as much computational effort. This task is still a challenge for the widely used local density or generalized gradient approximations (LDA/GGA) and hybrid functionals. One remedy, termed density functional theory plus U (DFT+U) approach, introduces a Hubbard U term to deal with the localized electrons at marginal computational cost, while treats the delocalized electrons with LDA/GGA. Here, we employ the DFT+U approach to investigate the T(c) of a pair of iron(II) SCO molecular crystals (α and β phase), where identical constituent molecules are packed in different ways. We first calculate the adiabatic high spin-low spin energy splitting ΔE(HL) and molecular vibrational frequencies in both spin states, then obtain the temperature dependent enthalpy and entropy changes (ΔH and ΔS), and finally extract T(c) by exploiting the ΔH/T - T and ΔS - T relationships. The results are in agreement with <span class="hlt">experiment</span>. Analysis of geometries and electronic structures shows that the local ligand field in the α phase is slightly weakened by the H-bondings involving the ligand atoms and the specific crystal packing style. We find that this effect is largely responsible for the difference in T(c) of the two phases. This study shows the applicability of the DFT+U approach for predicting T(c) of SCO materials, and provides a clear insight into the subtle influence of the crystal packing effects on SCO behavior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4565576','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4565576"><span>Continuous and Discontinuous Dynamic <span class="hlt">Crossover</span> in Supercooled Water in Computer Simulations</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2016-01-01</p> <p>The dynamic <span class="hlt">crossover</span> behavior of supercooled water as described by the first-principle based WAIL potential was investigated. Below the second liquid–liquid critical point, the viscosity shows a discontinuous jump consistent with a first-order phase transition between the high density liquid and the low density liquid. Above the critical point, a continuous transition occurs with only the first derivative of viscosity being discontinuous, and the dynamic <span class="hlt">crossover</span> temperature is about 8 K below the thermodynamic switchover temperature. The 8 K shift can be explained by a delay in dynamic <span class="hlt">crossover</span>, which does not occur until the more viscous liquid starts to dominate the population and jams the flow. On the basis of finite-size effects observed in our simulations, we believe that dynamic discontinuity may be observable above the critical point in confined water when the confinement is on a length scale shorter than the spatial correlation. PMID:27476514</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.4863V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.4863V"><span>Influence of the iron spin <span class="hlt">crossover</span> in ferropericlase on the lower mantle geotherm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Valencia-Cardona, Juan J.; Shukla, Gaurav; Wu, Zhongqing; Houser, Christine; Yuen, David A.; Wentzcovitch, Renata M.</p> <p>2017-05-01</p> <p>The iron spin <span class="hlt">crossover</span> in ferropericlase introduces anomalies in its thermodynamics and thermoelastic properties. Here we investigate how these anomalies can affect the lower mantle geotherm using thermodynamics properties from ab initio calculations. The anomalous effect is examined in mantle aggregates consisting of mixtures of bridgmanite, ferropericlase, and CaSiO3 perovskite, with different Mg/Si ratios varying from harzburgitic to perovskitic (Mg/Si ˜ 1.5 to 0.8). We find that the anomalies introduced by the spin <span class="hlt">crossover</span> increase the isentropic gradient and thus the geotherm proportionally to the amount of ferropericlase. The geotherms can be as much as ˜200 K hotter than the conventional adiabatic geotherm at deep lower mantle conditions. Aggregate elastic moduli and seismic velocities are also sensitive to the spin <span class="hlt">crossover</span> and the geotherm, which impacts analyses of lower mantle velocities and composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17677668','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17677668"><span>Experimental observation of structural <span class="hlt">crossover</span> in binary mixtures of colloidal hard spheres.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Baumgartl, Jörg; Dullens, Roel P A; Dijkstra, Marjolein; Roth, Roland; Bechinger, Clemens</p> <p>2007-05-11</p> <p>Using confocal microscopy, we investigate the structure of binary mixtures of colloidal hard spheres with size ratio q=0.61. As a function of the packing fraction of the two particle species, we observe a marked change of the dominant wavelength in the pair-correlation function. This behavior is in excellent agreement with a recently predicted structural <span class="hlt">crossover</span> in such mixtures. In addition, the repercussions of structural <span class="hlt">crossover</span> on the real-space structure of a binary fluid are analyzed. We suggest a relation between <span class="hlt">crossover</span> and the lateral extension of networks containing only equally-sized particles that are connected by nearest-neighbor bonds. This is supported by Monte Carlo simulations which are performed at different packing fractions and size ratios.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005PhRvE..71c6136G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005PhRvE..71c6136G"><span>Possible <span class="hlt">crossover</span> of a nonuniversal quantity at the upper critical dimension</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Galam, S.; Mauger, A.</p> <p>2005-03-01</p> <p>We report on a possible <span class="hlt">crossover</span> of a nonuniversal quantity at the upper critical dimensionality in the field of percolation. Plotting recent estimates for site percolation thresholds of hypercubes in dimension 6⩽d⩽13 against corresponding predictions from the Galam-Mauger (GM) formula pc=p0[(d-1)(q-1)]-adb for percolation thresholds, a significant departure of pc is observed for d⩾6 . This result is reminiscent of the <span class="hlt">crossover</span> undergone by universal quantities in critical phenomena. For bond percolation, evidence of such a <span class="hlt">crossover</span> of dimensionality would require an improvement of the GM formula to reach a relative error of typically 0.2%, while it is currently at 0.9% for hypercubes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20863949','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20863949"><span>BCS-BEC <span class="hlt">crossover</span> in atomic Fermi gases with a narrow resonance</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jensen, L. M.; Nilsen, H. M.; Watanabe, Gentaro</p> <p>2006-10-15</p> <p>We determine the effects on the BCS-BEC <span class="hlt">crossover</span> of the energy dependence of the effective two-body interaction, which at low energies is determined by the effective range. To describe interactions with an effective range of either sign, we consider a single-channel model with a two-body interaction having an attractive square well and a repulsive square barrier. We investigate the two-body scattering properties of the model, and then solve the Eagles-Leggett equations for the zero temperature <span class="hlt">crossover</span>, determining the momentum dependent gap and the chemical potential self-consistently. From this we investigate the dependence of the <span class="hlt">crossover</span> on the effective range of the interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EPJST.226.2793M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EPJST.226.2793M"><span>Correlation length and universality in the BCS-BEC <span class="hlt">crossover</span> for energy-dependent resonance superfluidity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Musolino, S.; Chiofalo, M.-L.</p> <p>2017-07-01</p> <p>We consider the BCS-BEC <span class="hlt">crossover</span> of a quantum Fermi gas at T = 0 in the presence of an energy-dependent Fano-Feshbach resonance, driving the system from broad to narrow limits. We choose a minimal microscopic potential reproducing the two-particle resonance physics in terms of the scattering length a and the effective range R∗ representing the resonance width, and solve the BCS mean-field equations varying a, R∗ and the density. We show that the condensate fraction manifests a universal behavior when the correlation length, measuring the pair size, is used as the <span class="hlt">crossover</span> parameter. Generally, a negative effective range has the effect of stretching the <span class="hlt">crossover</span> region between the two extreme regimes, as evidenced by the behavior of the chemical potential. These results can be useful in view of the more recent perspectives of realizing narrow resonances also by optical means and amenable as a base quantum Monte Carlo simulations.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22591410','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22591410"><span>Universal temperature <span class="hlt">crossover</span> behavior of electrical conductance in a single oligothiophene molecular wire.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, See Kei; Yamada, Ryo; Tanaka, Shoji; Chang, Gap Soo; Asai, Yoshihiro; Tada, Hirokazu</p> <p>2012-06-26</p> <p>We have observed and analyzed a universal temperature <span class="hlt">crossover</span> behavior of electrical conductance in a single oligothiophene molecular wire. The <span class="hlt">crossover</span> between the Arrhenius-type temperature dependence at high temperature and the temperature-invariant behavior at low temperature is found at a critical molecular wire length of 5.6 nm, where we found a change from the exponential length dependence to the length-invariant behavior. We have derived a scaling function analysis for the origin of the <span class="hlt">crossover</span> behavior. After assuring that the analysis fits the explanation of the Keldysh Green's function calculation for the temperature dependence, we have applied it to our experimental results and found successfully that our scaling function gives a universal description of the temperature dependence for all over the temperature range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvB..94w5110H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvB..94w5110H"><span>Detecting phase transitions and <span class="hlt">crossovers</span> in Hubbard models using the fidelity susceptibility</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Li; Wang, Yilin; Wang, Lei; Werner, Philipp</p> <p>2016-12-01</p> <p>A generalized version of the fidelity susceptibility of single-band and multiorbital Hubbard models is systematically studied using single-site dynamical mean-field theory in combination with a hybridization expansion continuous-time quantum Monte Carlo impurity solver. We find that the fidelity susceptibility is extremely sensitive to changes in the state of the system. It can be used as a numerically inexpensive tool to detect and characterize a broad range of phase transitions and <span class="hlt">crossovers</span> in Hubbard models, including (orbital-selective) Mott metal-insulator transitions, magnetic phase transitions, high-spin to low-spin transitions, Fermi-liquid to non-Fermi-liquid <span class="hlt">crossovers</span>, and spin-freezing <span class="hlt">crossovers</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvL.117w5301R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvL.117w5301R"><span>1D to 3D <span class="hlt">Crossover</span> of a Spin-Imbalanced Fermi Gas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Revelle, Melissa C.; Fry, Jacob A.; Olsen, Ben A.; Hulet, Randall G.</p> <p>2016-12-01</p> <p>We have characterized the one-dimensional (1D) to three-dimensional (3D) <span class="hlt">crossover</span> of a two-component spin-imbalanced Fermi gas of 6Li atoms in a 2D optical lattice by varying the lattice tunneling and the interactions. The gas phase separates, and we detect the phase boundaries using in situ imaging of the inhomogeneous density profiles. The locations of the phases are inverted in 1D as compared to 3D, thus providing a clear signature of the <span class="hlt">crossover</span>. By scaling the tunneling rate t with respect to the pair binding energy ɛB, we observe a collapse of the data to a universal <span class="hlt">crossover</span> point at a scaled tunneling value of t˜c=0.025 (7 ).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12659197','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12659197"><span>Splitter imperfections in annular split-flow thin separation channels: effect on nonspecific <span class="hlt">crossover</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Williams, P Stephen; Moore, Lee R; Chalmers, Jeffrey J; Zborowski, Maciej</p> <p>2003-03-15</p> <p>The separation performance of split-flow thin (SPLITT) separation channels generally falls short of ideal behavior. There are many possible contributing factors to the loss of separation resolution, and these are discussed in the text. The possibility that small imperfections in the splitters play a significant role is examined in this study. Computational fluid dynamics is used to determine the flow pattern within an annular SPLITT channel having small imperfections in the inlet splitter. These results are used to calculate the nonspecific <span class="hlt">crossover</span> of particles from the inner annular inlet to the outer annular outlet under various flow rate regimes. Nonspecific <span class="hlt">crossover</span>, obtained through convective transport alone, and not the result of field-induced transport, is often used as a check of channel behavior. The results of a typical experimental determination of nonspecific <span class="hlt">crossover</span> are included for comparison. It is concluded that geometrical imperfections can indeed play a significant role in the loss of resolution observed for these systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28149725','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28149725"><span>Correction of <span class="hlt">Crossover</span> Toe Deformity by Arthroscopically Assisted Plantar Plate Tenodesis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lui, Tun Hing</p> <p>2016-12-01</p> <p>Plantar plate deficiency is the major pathology causing metatarsophalangeal joint instability. As the joint subluxates dorsally, the lumbrical is tethered at the medial side of the joint by the deep metatarsal ligament and becomes a deforming force for the development of <span class="hlt">crossover</span> toe deformity. Plantar plate repair or reconstruction is a logical surgical treatment option. This can be performed through a dorsal or plantar approach. The purpose of this technical note is to report a minimally invasive technique of <span class="hlt">crossover</span> toe deformity correction by suturing the plantar plate to the extensor tendon. It is indicated for symptomatic <span class="hlt">crossover</span> toe deformity that is not responsive to nonsurgical treatment. It is contraindicated if the metatarsophalangeal joint is degenerated, destructed, or dislocated, or there is interdigital neuroma at the sides of the deformed toe, or the deformity is caused by bony deformities of the metatarsal head or the proximal phalanx.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3998905','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3998905"><span>A Quality Control Mechanism Coordinates Meiotic Prophase Events to Promote <span class="hlt">Crossover</span> Assurance</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Deshong, Alison J.; Ye, Alice L.; Lamelza, Piero; Bhalla, Needhi</p> <p>2014-01-01</p> <p>Meiotic chromosome segregation relies on homologous chromosomes being linked by at least one <span class="hlt">crossover</span>, the obligate <span class="hlt">crossover</span>. Homolog pairing, synapsis and meiosis specific DNA repair mechanisms are required for <span class="hlt">crossovers</span> but how they are coordinated to promote the obligate <span class="hlt">crossover</span> is not well understood. PCH-2 is a highly conserved meiotic AAA+-ATPase that has been assigned a variety of functions; whether these functions reflect its conserved role has been difficult to determine. We show that PCH-2 restrains pairing, synapsis and recombination in C. elegans. Loss of pch-2 results in the acceleration of synapsis and homolog-dependent meiotic DNA repair, producing a subtle increase in meiotic defects, and suppresses pairing, synapsis and recombination defects in some mutant backgrounds. Some defects in pch-2 mutants can be suppressed by incubation at lower temperature and these defects increase in frequency in wildtype worms grown at higher temperature, suggesting that PCH-2 introduces a kinetic barrier to the formation of intermediates that support pairing, synapsis or <span class="hlt">crossover</span> recombination. We hypothesize that this kinetic barrier contributes to quality control during meiotic prophase. Consistent with this possibility, defects in pch-2 mutants become more severe when another quality control mechanism, germline apoptosis, is abrogated or meiotic DNA repair is mildly disrupted. PCH-2 is expressed in germline nuclei immediately preceding the onset of stable homolog pairing and synapsis. Once chromosomes are synapsed, PCH-2 localizes to the SC and is removed in late pachytene, prior to SC disassembly, correlating with when homolog-dependent DNA repair mechanisms predominate in the germline. Indeed, loss of pch-2 results in premature loss of homolog access. Altogether, our data indicate that PCH-2 coordinates pairing, synapsis and recombination to promote <span class="hlt">crossover</span> assurance. Specifically, we propose that the conserved function of PCH-2 is to destabilize pairing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22251489','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22251489"><span>Temperature effect on the small-to-large <span class="hlt">crossover</span> lengthscale of hydrophobic hydration</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Djikaev, Y. S. Ruckenstein, E.</p> <p>2013-11-14</p> <p>The thermodynamics of hydration is expected to change gradually from entropic for small solutes to enthalpic for large ones. The small-to-large <span class="hlt">crossover</span> lengthscale of hydrophobic hydration depends on the thermodynamic conditions of the solvent such as temperature, pressure, presence of additives, etc. We attempt to shed some light on the temperature dependence of the <span class="hlt">crossover</span> lengthscale by using a probabilistic approach to water hydrogen bonding that allows one to obtain an analytic expression for the number of bonds per water molecule as a function of both its distance to a solute and solute radius. Incorporating that approach into the density functional theory, one can examine the solute size effects on its hydration over the entire small-to-large lengthscale range at a series of different temperatures. Knowing the dependence of the hydration free energy on the temperature and solute size, one can also obtain its enthalpic and entropic contributions as functions of both temperature and solute size. These functions can provide some interesting insight into the temperature dependence of the <span class="hlt">crossover</span> lengthscale of hydrophobic hydration. The model was applied to the hydration of spherical particles of various radii in water in the temperature range from T = 293.15 K to T = 333.15 K. The model predictions for the temperature dependence of the hydration free energy of small hydrophobes are consistent with the experimental and simulational data on the hydration of simple molecular solutes. Three alternative definitions for the small-to-large <span class="hlt">crossover</span> length-scale of hydrophobic hydration are proposed, and their temperature dependence is obtained. Depending on the definition and temperature, the small-to-large <span class="hlt">crossover</span> in the hydration mechanism is predicted to occur for hydrophobes of radii from one to several nanometers. Independent of its definition, the <span class="hlt">crossover</span> length-scale is predicted to decrease with increasing temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24320293','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24320293"><span>Temperature effect on the small-to-large <span class="hlt">crossover</span> lengthscale of hydrophobic hydration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Djikaev, Y S; Ruckenstein, E</p> <p>2013-11-14</p> <p>The thermodynamics of hydration is expected to change gradually from entropic for small solutes to enthalpic for large ones. The small-to-large <span class="hlt">crossover</span> lengthscale of hydrophobic hydration depends on the thermodynamic conditions of the solvent such as temperature, pressure, presence of additives, etc. We attempt to shed some light on the temperature dependence of the <span class="hlt">crossover</span> lengthscale by using a probabilistic approach to water hydrogen bonding that allows one to obtain an analytic expression for the number of bonds per water molecule as a function of both its distance to a solute and solute radius. Incorporating that approach into the density functional theory, one can examine the solute size effects on its hydration over the entire small-to-large lengthscale range at a series of different temperatures. Knowing the dependence of the hydration free energy on the temperature and solute size, one can also obtain its enthalpic and entropic contributions as functions of both temperature and solute size. These functions can provide some interesting insight into the temperature dependence of the <span class="hlt">crossover</span> lengthscale of hydrophobic hydration. The model was applied to the hydration of spherical particles of various radii in water in the temperature range from T = 293.15 K to T = 333.15 K. The model predictions for the temperature dependence of the hydration free energy of small hydrophobes are consistent with the experimental and simulational data on the hydration of simple molecular solutes. Three alternative definitions for the small-to-large <span class="hlt">crossover</span> length-scale of hydrophobic hydration are proposed, and their temperature dependence is obtained. Depending on the definition and temperature, the small-to-large <span class="hlt">crossover</span> in the hydration mechanism is predicted to occur for hydrophobes of radii from one to several nanometers. Independent of its definition, the <span class="hlt">crossover</span> length-scale is predicted to decrease with increasing temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMMR24A..07W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMMR24A..07W"><span>Spin <span class="hlt">crossover</span> in ferropericlase and velocity heterogeneities in the lower mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Z.; Wentzcovitch, R. M.</p> <p>2014-12-01</p> <p>Ferropericlase (Fp) is believed to be the second most abundant phase in the lower mantle. Since the discovery of the high spin (HS) to low spin (LS) <span class="hlt">crossover</span> in iron in Fp [1], this phenomenon has been investigated extensively experimentally and theoretically. This is a broad and smooth <span class="hlt">crossover</span> that takes place throughout most of the lower mantle and does not produce an obvious signature in radial velocity or density profiles [2]. Therefore, the spin transition has been generally considered to be invisible to seismic waves. This study, however, shows that it can produce a peculiar effect on lateral velocity heterogeneities at certain depths[3]. Deciphering the origin of seismic velocity heterogeneities in the mantle is crucial to understanding internal structures and processes at work in the Earth. The spin <span class="hlt">crossover</span> in iron introduces unfamiliar effects on seismic velocities. First principles calculations indicate that anti-correlation between shear velocity (VS) and bulk sound velocity (Vφ) in the mantle, usually interpreted as compositional heterogeneity, can also be produced in homogeneous aggregates containing Fp. The spin <span class="hlt">crossover</span> also suppresses thermally induced heterogeneity in VP but not in VS. This effect is observed in tomographic models at conditions where the spin <span class="hlt">crossover</span> in Fp is expected in the lower mantle. In addition, the one-of-a-kind signature of this spin <span class="hlt">crossover</span> in the RS/P () heterogeneity ratio might be a useful "fingerprint" to detect the presence of Fp in the lower mantle. [1] Badro J, et al. (2003) Science 300(5620):789-791. [2] Wu Z, Justo J. F., and Wentzcovitch R. M., (2013). Phys. Rev. Lett. 110. 228501-5 [3]Wu Z., and Wentzcovitch R. M., (2014) Proc Natl Acad Sci USA. www.pnas.org/cgi/doi/10.1073/pnas.1322427111</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998JPCM...10.6083V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998JPCM...10.6083V"><span>General resistance <span class="hlt">crossover</span> expressions for three-dimensional variable-range hopping</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Van Lien, Nguyen; Rosenbaum, Ralph</p> <p>1998-07-01</p> <p>We observe a <span class="hlt">crossover</span> in the temperature dependence of the variable-range-hopping resistivity in a three-dimensional nickel-silicon film from the Mott 0953-8984/10/27/009/img5-behaviour to the soft-gap 0953-8984/10/27/009/img6-behaviour with 0953-8984/10/27/009/img7. We propose general expressions for describing such <span class="hlt">crossovers</span> from 0953-8984/10/27/009/img5-behaviour to 0953-8984/10/27/009/img6-behaviour for any 0953-8984/10/27/009/img10 from 1/4 to 1. The theoretical expressions fit the experimental data well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NuPhB.916..304Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NuPhB.916..304Z"><span>Holographic entanglement entropy close to <span class="hlt">crossover</span>/phase transition in strongly coupled systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Shao-Jun</p> <p>2017-03-01</p> <p>We investigate the behavior of entanglement entropy in the holographic QCD model proposed by Gubser et al. By choosing suitable parameters of the scalar self-interaction potential, this model can exhibit various types of phase structures: <span class="hlt">crossover</span>, first order and second order phase transitions. We use entanglement entropy to probe the <span class="hlt">crossover</span>/phase transition, and find that it drops quickly/suddenly when the temperature approaches the critical point which can be seen as a signal of confinement. Moreover, the critical behavior of the entanglement entropy suggests that we may use it to characterize the corresponding phase structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21123640','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21123640"><span>Examining the <span class="hlt">Crossover</span> from the Hadronic to Partonic Phase in QCD</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Xu Mingmei; Yu Meiling; Liu Lianshou</p> <p>2008-03-07</p> <p>A mechanism, consistent with color confinement, for the transition between perturbative and physical vacua during the gradual <span class="hlt">crossover</span> from the hadronic to partonic phase is proposed. The essence of this mechanism is the appearance and growing up of a kind of grape-shape perturbative vacuum inside the physical one. A percolation model based on simple dynamics for parton delocalization is constructed to exhibit this mechanism. The <span class="hlt">crossover</span> from hadronic matter to sQGP (strongly coupled quark-gluon plasma) as well as the transition from sQGP to weakly coupled quark-gluon plasma with increasing temperature is successfully described by using this model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JChPh.139d4509P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JChPh.139d4509P"><span>Cooperative dynamic and diffusion behavior above and below the dynamical <span class="hlt">crossover</span> of supercooled water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Picasso, Germán C.; Malaspina, David C.; Carignano, Marcelo A.; Szleifer, Igal</p> <p>2013-07-01</p> <p>Using extensive molecular dynamics simulations combined with a novel approach to analyze the molecular displacements we analyzed the change in the dynamics above and below the <span class="hlt">crossover</span> temperature Tx for supercooled water. Our findings suggest that the <span class="hlt">crossover</span> from fragile to strong glass former occurring at Tx is related with a change in the diffusion mechanism evidencing the presence of jump-like diffusion at lower temperatures. Also we observe that fluctuations of the local environments are intimately connected with fluctuations in the size and the amount of cooperative cluster of mobile molecules, and in particular we find a highly cooperative nature of the motion at low temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5027514','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5027514"><span>Self-assembly of fully addressable DNA nanostructures from double <span class="hlt">crossover</span> tiles</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Wen; Lin, Tong; Zhang, Suoyu; Bai, Tanxi; Mi, Yongli; Wei, Bryan</p> <p>2016-01-01</p> <p>DNA origami and single-stranded tile (SST) are two proven approaches to self-assemble finite-size complex DNA nanostructures. The construction elements appeared in structures from these two methods can also be found in multi-stranded DNA tiles such as double <span class="hlt">crossover</span> tiles. Here we report the design and observation of four types of finite-size lattices with four different double <span class="hlt">crossover</span> tiles, respectively, which, we believe, in terms of both complexity and robustness, will be rival to DNA origami and SST structures. PMID:27484479</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhB...50k4002H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhB...50k4002H"><span><span class="hlt">Cross-over</span> to quasi-condensation: mean-field theories and beyond</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Henkel, Carsten; Sauer, Tim-O.; Proukakis, N. P.</p> <p>2017-06-01</p> <p>We analyze the <span class="hlt">cross-over</span> of a homogeneous, weakly interacting Bose gas in one dimension from the ideal gas into the dense quasi-condensate phase. We review a number of mean-field theories, perturbative or self-consistent, and provide accurate evaluations of equation of state, density fluctuations, and correlation functions. A smooth <span class="hlt">crossover</span> is reproduced by classical-field simulations based on the stochastic Gross-Pitaevskii equation and the Yang-Yang solution to the one-dimensional Bose gas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000058175','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000058175"><span>Recent Studies on Methanol <span class="hlt">Crossover</span> in Liquid-Feed Direct Methanol Fuel Cells</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Valdez, T. I.; Narayanan, S. R.</p> <p>2000-01-01</p> <p>In this work, the effects of methanol <span class="hlt">crossover</span> and airflow rates on the cathode potential of an operating direct methanol fuel cell are explored. Techniques for quantifying methanol <span class="hlt">crossover</span> in a fuel cell and for separating the electrical performance of each electrode in a fuel cell are discussed. The effect of methanol concentration on cathode potential has been determined to be significant. The cathode is found to be mass transfer limited when operating on low flow rate air and high concentrations of methanol. Improvements in cathode structure and operation at low methanol concentration have been shown to result in improved cell performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12225111','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12225111"><span><span class="hlt">Crossover</span> between universality classes in the statistics of rare events in disordered conductors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Apalkov, V M; Raikh, M E; Shapiro, B</p> <p>2002-09-16</p> <p>The <span class="hlt">crossover</span> from orthogonal to the unitary universality classes in the distribution of the anomalously localized states (ALS) in two-dimensional disordered conductors is traced as a function of magnetic field. We demonstrate that the microscopic origin of the <span class="hlt">crossover</span> is the change in the symmetry of the underlying disorder configurations that are responsible for ALS. These disorder configurations are of weak magnitude (compared to the Fermi energy) and of small size (compared to the mean free path). We find their shape explicitly by means of the direct optimal fluctuation method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvB..95b4205K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvB..95b4205K"><span>Universal <span class="hlt">crossover</span> from ground-state to excited-state quantum criticality</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kang, Byungmin; Potter, Andrew C.; Vasseur, Romain</p> <p>2017-01-01</p> <p>We study the nonequilibrium properties of a nonergodic random quantum chain in which highly excited eigenstates exhibit critical properties usually associated with quantum critical ground states. The ground state and excited states of this system belong to different universality classes, characterized by infinite-randomness quantum critical behavior. Using strong-disorder renormalization group techniques, we show that the <span class="hlt">crossover</span> between the zero and finite energy density regimes is universal. We analytically derive a flow equation describing the unitary dynamics of this isolated system at finite energy density from which we obtain universal scaling functions along the <span class="hlt">crossover</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1100779','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1100779"><span>Molecular dynamics studies of heterogeneous dynamics and dynamic <span class="hlt">crossover</span> in supercooled atomic liquids</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Andersen, Hans C.</p> <p>2005-01-01</p> <p>Supercooled liquids near the glass transition exhibit the phenomenon of heterogeneous relaxation; at any specific time, a nominally homogeneous equilibrium fluid undergoes dynamic fluctuations in its structure on a molecular distance scale with rates that are very different in different regions of the sample. Several theoretical and simulation studies have suggested a change in the nature of the dynamics of fluids as they are supercooled, leading to the concept of a dynamic <span class="hlt">crossover</span> that is often associated with mode coupling theory. Here, we will review the use of molecular dynamics computer simulation methods to investigate heterogeneous dynamics and dynamic <span class="hlt">crossovers</span> in models of atomic liquids. PMID:15870201</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JChPh.142u5102B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JChPh.142u5102B"><span><span class="hlt">Crossover</span> of two power laws in the anomalous diffusion of a two lipid membrane</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bakalis, Evangelos; Höfinger, Siegfried; Venturini, Alessandro; Zerbetto, Francesco</p> <p>2015-06-01</p> <p>Molecular dynamics simulations of a bi-layer membrane made by the same number of 1-palmitoyl-2-oleoyl-glycero-3-phospho-ethanolamine and palmitoyl-oleoyl phosphatidylserine lipids reveal sub-diffusional motion, which presents a <span class="hlt">crossover</span> between two different power laws. Fractional Brownian motion is the stochastic mechanism that governs the motion in both regimes. The location of the <span class="hlt">crossover</span> point is justified with simple geometrical arguments and is due to the activation of the mechanism of circumrotation of lipids about each other.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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