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Luca Baiotti, Luciano Rezzolla
The merger of binary neutron-stars systems combines in a single process: extreme gravity, copious emission of gravitational waves, complex microphysics, and electromagnetic processes that can lead to astrophysical signatures observable at the largest redshifts. We review here the recent progress in understanding what could be considered Einstein's richest laboratory, highlighting in particular the numerous significant advances of the last decade. Although special attention is paid to the status of models, techniques, and results for fully general-relativistic dynamical simulations, a review is also offered on initial data and advanced simulations with approximate treatments of gravity...
March 20, 2017: Reports on Progress in Physics
Daniel E Hurtado, Nicolás Villarroel, Carlos Andrade, Jaime Retamal, Guillermo Bugedo, Alejandro Bruhn
Understanding regional deformation in the lung has long attracted the medical community, as parenchymal deformation plays a key role in respiratory physiology. Recent advances in image registration make it possible to noninvasively study regional deformation, showing that volumetric deformation in healthy lungs follows complex spatial patterns not necessarily shared by all subjects, and that deformation can be highly anisotropic. In this work, we systematically study the regional deformation in the lungs of eleven human subjects by means of in vivo image-based biomechanical analysis...
March 18, 2017: Biomechanics and Modeling in Mechanobiology
Thomas E Collett, David Bacon
Probing the relative speeds of gravitational waves and light acts as an important test of general relativity and alternative theories of gravity. Measuring the arrival time of gravitational waves (GWs) and electromagnetic (EM) counterparts can be used to measure the relative speeds, but only if the intrinsic time lag between emission of the photons and gravitational waves is well understood. Here we suggest a method that does not make such an assumption, using future strongly lensed GW events and EM counterparts; Biesiada et al...
March 3, 2017: Physical Review Letters
Xi-Long Fan, Kai Liao, Marek Biesiada, Aleksandra Piórkowska-Kurpas, Zong-Hong Zhu
We propose a new model-independent measurement strategy for the propagation speed of gravitational waves (GWs) based on strongly lensed GWs and their electromagnetic (EM) counterparts. This can be done in two ways: by comparing arrival times of GWs and their EM counterparts and by comparing the time delays between images seen in GWs and their EM counterparts. The lensed GW-EM event is perhaps the best way to identify an EM counterpart. Conceptually, this method does not rely on any specific theory of massive gravitons or modified gravity...
March 3, 2017: Physical Review Letters
O Obidi, A H Muggeridge, V Vesovic
An alternative analytical solution is presented, based on irreversible thermodynamics, that describes the equilibrium distribution of the components of a nonideal fluid mixture in a one-dimensional hydrostatic and isothermal system. In such a system, the vertical compositional profile of the fluid at equilibrium will be determined by the interaction of gravitational and chemical potentials. Our alternative analytical solution estimates this profile from the overall composition of the fluid. It is thus more general than the existing solution, which requires knowledge of the fluid composition at a given depth and assumes that the vertical compositional profile of this fluid is already at equilibrium...
February 2017: Physical Review. E
Pankaj Kumar, Bruce N Miller, Dan Pirjol
We study the thermodynamic properties of a one-dimensional gas with one-dimensional gravitational interactions. Periodic boundary conditions are implemented as a modification of the potential consisting of a sum over mirror images (Ewald sum), regularized with an exponential cutoff. As a consequence, each particle carries with it its own background density. Using mean-field theory, we show that the system has a phase transition at a critical temperature. Above the critical temperature the gas density is uniform, while below the critical point the system becomes inhomogeneous...
February 2017: Physical Review. E
Hiroshi Gotoda, Hiroaki Kobayashi, Kenta Hayashi
We have intensively examined the dynamic behavior of flame front instability in a lean swirling premixed flame generated by a change in gravitational orientation [H. Gotoda, T. Miyano, and I. G. Shepherd, Phys. Rev. E 81, 026211 (2010)PLEEE81539-375510.1103/PhysRevE.81.026211] from the viewpoints of complex networks, symbolic dynamics, and statistical complexity. Here, we considered the permutation entropy in combination with the surrogate data method, the permutation spectrum test, and the multiscale complexity-entropy causality plane incorporating a scale-dependent approach, none of which have been considered in the study of flame front instabilities...
February 2017: Physical Review. E
Chin-Feng Lai, Ren-Hung Hwang, Ying-Hsun Lai
Sensors can be installed on various body parts to provide information for computer diagnosis to identify the current body state. However, as human posture is subject to gravity, the direction of the force on each limb differs. For example, the directions of gravitational force on legs and trunk differ. In addition, each person's height and structure of limbs differs, hence, the acceleration and rotation resulted from such differences on force and length of the limbs of a person in motion would be different, and be presented by cases of different postures...
April 2017: Journal of Medical Systems
Johannes Schönke, Eliot Fried
A linear stability analysis is performed for a pair of coaxial vertical chains made from permanently magnetized balls under the influence of gravity. While one chain rises from the ground, the other hangs from above, with the remaining ends separated by a gap of prescribed length. Various boundary conditions are considered, as are situations in which the magnetic dipole moments in the two chains are parallel or antiparallel. The case of a single chain attached to the ground is also discussed. The stability of the system is examined with respect to three quantities: the number of balls in each chain, the length of the gap between the chains, and a single dimensionless parameter which embodies the competition between magnetic and gravitational forces...
February 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
Daegeun Park, Kyu-Jin Cho
Compensating the weight of human limbs is important in reducing muscle fatigue experienced by manual laborers. In this study, a compact and lightweight soft wearable weight support device was developed and evaluated. The device supports gravitational force on the shoulder at any arm posture, although there are some limitations in its assistive performance. The device actuator consists of a cam-rod structure, a tendon-driven mechanism, and a rubber band. The desired assistive torque is translated to the shoulder joint along a tendon routing structure...
2017: PloS One
Chor Yong Tay, Magdiel Inggrid Setyawati, David Tai Leong
The integrity of the vasculature system is intrinsically sensitive to a short list of biophysical cues spanning from nano to micro scales. We have earlier found that certain nanoparticles could induce endothelial leakiness (nanoparticle induced endothelial leakiness, NanoEL). In this study, we report that the intrinsic density of the nanomaterial, a basic intrinsic material property not implicated in many nanoparticle-mediated biological effects, predominantly dictates the NanoEL effect. We demonstrated that the impinging force exerted by a library of increasing effective densities but consistently sized silica nanoparticles (SiNPs) could directly increase endothelial permeability...
March 13, 2017: ACS Nano
Matthew M Scase, Kyle A Baldwin, Richard J A Hill
Classical techniques for investigating the Rayleigh-Taylor instability include using compressed gasses(1), rocketry(2) or linear electric motors(3) to reverse the effective direction of gravity, and accelerate the lighter fluid toward the denser fluid. Other authors(e.g.)(4)(,)(5)(,)(6) have separated a gravitationally unstable stratification with a barrier that is removed to initiate the flow. However, the parabolic initial interface in the case of a rotating stratification imposes significant technical difficulties experimentally...
March 3, 2017: Journal of Visualized Experiments: JoVE
Vassiliki Kalogera, Albert Lazzarini
A unique window on the universe opened on September 14, 2015, with direct detection of gravitational waves by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors. This event culminated a half-century effort around the globe to develop terrestrial detectors of adequate sensitivity to achieve this goal. It also happened appropriately only a few months before the centennial of Einstein's final paper introducing the general theory of relativity. This detection provided the surprising discovery of a coalescing pair of "heavy" black holes (more massive than [Formula: see text] M[Formula: see text]) leading to the formation of a spinning [Formula: see text]62 solar mass black hole...
March 10, 2017: Proceedings of the National Academy of Sciences of the United States of America
Mitch Jacoby
No abstract text is available yet for this article.
February 22, 2017: ACS Central Science
Daniele Pezzoli, Elisa Giupponi, Diego Mantovani, Gabriele Candiani
Although branched and linear polyethylenimines (bPEIs and lPEIs) are gold standard transfectants, a systematic analysis of the effects of the preparation protocol of polyplexes and the composition of the transfection medium on their physicochemical behaviour and effectiveness in vitro have been much neglected, undermining in some way the identification of precise structure-function relationships. This work aimed to address these issues. bPEI/DNA and lPEI/DNA, prepared using two different modes of addition of reagents, gave rise to polyplexes with exactly the same chemical composition but differing in dimensions...
March 8, 2017: Scientific Reports
Esteban Castro Ruiz, Flaminia Giacomini, Časlav Brukner
In general relativity, the picture of space-time assigns an ideal clock to each world line. Being ideal, gravitational effects due to these clocks are ignored and the flow of time according to one clock is not affected by the presence of clocks along nearby world lines. However, if time is defined operationally, as a pointer position of a physical clock that obeys the principles of general relativity and quantum mechanics, such a picture is, at most, a convenient fiction. Specifically, we show that the general relativistic mass-energy equivalence implies gravitational interaction between the clocks, whereas the quantum mechanical superposition of energy eigenstates leads to a nonfixed metric background...
March 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
Deanna C Easley, Steven D Abramowitch, Pamela A Moalli
PURPOSE OF REVIEW: The pelvic floor is a complex assembly of connective tissues and striated muscles that simultaneously counteracts gravitational forces, inertial forces, and intra-abdominal pressures while maintaining the position of the pelvic organs. In 30% of women, injury or failure of the pelvic floor results in pelvic organ prolapse. Surgical treatments have high recurrence rates, due, in part, to a limited understanding of physiologic loading conditions. It is critical to apply biomechanics to help elucidate how altered loading conditions of the pelvis contribute to the development of pelvic organ prolapse and to define surgeries to restore normal support...
March 4, 2017: Current Opinion in Urology
Arnald Puy, Rachata Muneepeerakul, Andrea L Balbo
This paper presents a systematic study of the relation between the size of irrigation systems and the management of uncertainty. We specifically focus on studying, through a stylized theoretical model, how stochasticity in water availability and taxation interacts with the stochastic behavior of the population within irrigation systems. Our results indicate the existence of two key population thresholds for the sustainability of any irrigation system: or the critical population size required to keep the irrigation system operative, and N* or the population threshold at which the incentive to work inside the irrigation system equals the incentives to work elsewhere...
March 7, 2017: Scientific Reports
Rohan Patil, Jason Walther
Continuous biomanufacturing of recombinant therapeutic proteins offers several potential advantages over conventional batch processing, including reduced cost of goods, more flexible and responsive manufacturing facilities, and improved and consistent product quality. Although continuous approaches to various upstream and downstream unit operations have been considered and studied for decades, in recent years interest and application have accelerated. Researchers have achieved increasingly higher levels of process intensification, and have also begun to integrate different continuous unit operations into larger, holistically continuous processes...
March 7, 2017: Advances in Biochemical Engineering/biotechnology
Ryohei Uchida, Ken Nakata, Fuminori Kawano, Yasukazu Yonetani, Issei Ogasawara, Naoya Nakai, Tatsuo Mae, Tomohiko Matsuo, Yuta Tachibana, Hiroyuki Yokoi, Hideki Yoshikawa
All living tissues and cells on Earth are subject to gravitational acceleration, but no reports have verified whether acceleration mode influences bone formation and healing. Therefore, this study was to compare the effects of two acceleration modes, vibration and constant (centrifugal) accelerations, on bone formation and healing in the trunk using BMP 2-induced ectopic bone formation (EBF) mouse model and a rib fracture healing (RFH) rat model. Additionally, we tried to verify the difference in mechanism of effect on bone formation by accelerations between these two models...
2017: PloS One
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