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G Ciani, M A Arain, S M Aston, D Feldbaum, P Fulda, J Gleason, M Heintze, R M Martin, C L Mueller, D M Nanda Kumar, A Pele, D H Reitze, P Sainathan, D B Tanner, L F Williams, G Mueller
We report on the design and performance of small optic suspensions developed to suppress seismic motion of out-of-cavity optics in the input optics subsystem of the Advanced Laser Interferometer Gravitational Wave Observatory. These compact single stage suspensions provide isolation in all six degrees of freedom of the optic, local sensing and actuation in three of them, and passive damping for the other three.
November 2016: Review of Scientific Instruments
Shao-Bo Qu, Xiao-Mei Xia, Yan-Zheng Bai, Shu-Chao Wu, Ze-Bing Zhou
The high precision space electrostatic accelerometer is an instrument to measure the non-gravitational forces acting on a spacecraft. It is one of the key payloads for satellite gravity measurements and space fundamental physics experiments. The measurement error of the accelerometer directly affects the precision of gravity field recovery for the earth. This paper analyzes the sources of the bias according to the operating principle and structural constitution of the space electrostatic accelerometer. Models of bias due to the asymmetry of the displacement sensing system, including the mechanical sensor head and the capacitance sensing circuit, and the asymmetry of the feedback control actuator circuit are described separately...
November 2016: Review of Scientific Instruments
S Karki, D Tuyenbayev, S Kandhasamy, B P Abbott, T D Abbott, E H Anders, J Berliner, J Betzwieser, C Cahillane, L Canete, C Conley, H P Daveloza, N De Lillo, J R Gleason, E Goetz, K Izumi, J S Kissel, G Mendell, V Quetschke, M Rodruck, S Sachdev, T Sadecki, P B Schwinberg, A Sottile, M Wade, A J Weinstein, M West, R L Savage
The two interferometers of the Laser Interferometry Gravitational-wave Observatory (LIGO) recently detected gravitational waves from the mergers of binary black hole systems. Accurate calibration of the output of these detectors was crucial for the observation of these events and the extraction of parameters of the sources. The principal tools used to calibrate the responses of the second-generation (Advanced) LIGO detectors to gravitational waves are systems based on radiation pressure and referred to as photon calibrators...
November 2016: Review of Scientific Instruments
Jinzhou Yuan, Hungtang Ko, David M Raizen, Haim H Bau
Nematodes such as Caenorhabditis elegans are heavier than water. When submerged in water, they settle to the bottom surface. Observations reveal that the animals do not lie flat on the bottom surface, but remain substantially suspended above the surface through continuous collisions with the surface, while maintaining their swimming gaits. Consequently, the swimming animals follow the bottom surface topography. When the bottom surface is inclined, the animals swim up or down along the incline. As the magnitude of the gravitational force can be easily estimated, this behaviour provides a convenient means to estimate the animal's propulsive thrust...
November 2016: Journal of the Royal Society, Interface
Vuk Mandic, Simeon Bird, Ilias Cholis
Recent Advanced LIGO detections of binary black hole mergers have prompted multiple studies investigating the possibility that the heavy GW150914 binary system was of primordial origin, and hence could be evidence for dark matter in the form of black holes. We compute the stochastic background arising from the incoherent superposition of such primordial binary black hole systems in the Universe and compare it to the similar background spectrum due to binary black hole systems of stellar origin. We investigate the possibility of detecting this background with future gravitational-wave detectors, and conclude that constraining the dark matter component in the form of black holes using stochastic gravitational-wave background measurements will be very challenging...
November 11, 2016: Physical Review Letters
Antoni Sagrista, Stefan Jordan, Andreas Just, Fabio Dias, Luis Gustavo Nonato, Filip Sadlo
Traditional vector field visualization has a close focus on velocity, and is typically constrained to the dynamics of massless particles. In this paper, we present a novel approach to the analysis of the force-induced dynamics of inertial particles. These forces can arise from acceleration fields such as gravitation, but also be dependent on the particle dynamics itself, as in the case of magnetism. Compared to massless particles, the velocity of an inertial particle is not determined solely by its position and time in a vector field...
January 2017: IEEE Transactions on Visualization and Computer Graphics
Projjwal Banerjee, Yong-Zhong Qian, Alexander Heger, W C Haxton
About 4.6 billion years ago, some event disturbed a cloud of gas and dust, triggering the gravitational collapse that led to the formation of the solar system. A core-collapse supernova, whose shock wave is capable of compressing such a cloud, is an obvious candidate for the initiating event. This hypothesis can be tested because supernovae also produce telltale patterns of short-lived radionuclides, which would be preserved today as isotopic anomalies. Previous studies of the forensic evidence have been inconclusive, finding a pattern of isotopes differing from that produced in conventional supernova models...
November 22, 2016: Nature Communications
Ling Ding, Wenying Lv, Kun Yao, Liming Li, Mengmeng Wang, Guoguang Liu
Humin is the component of humic substances that is recalcitrant to extraction by either strong bases or strong acids, which contains a variety of functional groups that may combine with heavy metal ions. The present study employed humin as an adsorbent to investigate the efficacy of a remediation strategy under the effects of humin-enhanced electrokinetics. Because the cations gravitate toward cathode and anions are transferred to anode, humin was placed in close proximity to the cathode in the form of a package...
November 21, 2016: Environmental Science and Pollution Research International
Jessica M Oakes, Shawn C Shadden, Céline Grandmont, Irene E Vignon-Clementel
Little is known about transport throughout the respiration cycle in the conducting airways. It is challenging to appropriately describe the time-dependent number of particles entering back into the model during exhalation. Modeling the entire lung is not feasible; therefore multi-domain methods must be employed. Here, we present a new framework that is designed to simulate particles throughout the respiration cycle, incorporating realistic airway geometry and respiration. This framework is applied for a healthy rat lung exposed to  ∼ 1μm diameter particles to facilitate parameterization and validation...
November 2, 2016: International Journal for Numerical Methods in Biomedical Engineering
Sander Wildeman, Chao Sun
Leidenfrost droplets, i.e. droplets whose mobility is ensured by a thin vapor film between the droplet and a hot plate, are exposed to an external electric field. We find that in a strong vertical electric field the droplet can start to bounce progressively higher, defying gravitational attraction. From the droplet's trajectory we infer the temporal evolution of the amount of charge on the droplet. This reveals that the charge starts high and then decreases in steps as the droplet slowly evaporates. After each discharge event the charge is in a fixed proportion to the droplet's surface area...
November 18, 2016: Soft Matter
Melanie Ast, Sebastian Steinlechner, Roman Schnabel
Quantum-dense metrology constitutes a special case of quantum metrology in which two orthogonal phase space projections of a signal are simultaneously sensed beyond the shot-noise limit. Previously, it was shown that the additional sensing channel that is provided by quantum-dense metrology contains information that can be used to identify and to discard corrupted segments from the measurement data. Here, we propose and demonstrate a new method in which this information is used for improving the sensitivity without discarding any measurement segments...
October 28, 2016: Physical Review Letters
Yuan-Ming Lu, Bo Jiao, Jun Lee, Lin Zhang, Zhi-Bin Yu
Gravitation is an important factor in maintaining cardiac contractility. Our study investigated whether simulated microgravity increases myocardial susceptibility to ischemia-reperfusion (IR) injury. Using the Langendorff-perfused heart model with 300 beats/min pacing, 4-week tail suspension (SUS) and control (CON) male Sprague-Dawley rats (n = 10 rats/group) were subjected to 60 min of left anterior descending coronary artery (LAD) occlusion followed by 120 min of reperfusion. Left ventricular end-systolic pressure (LVESP), left ventricular end-diastolic pressure (LVEDP), creatine kinase (CK) and lactate dehydrogenase (LDH) activity, and infarct size were assessed...
September 1, 2016: Canadian Journal of Physiology and Pharmacology
David Garfinkle
Though the main applications of computer simulations in relativity are to astrophysical systems such as black holes and neutron stars, nonetheless there are important applications of numerical methods to the investigation of general relativity as a fundamental theory of the nature of space and time. This paper gives an overview of some of these applications. In particular we cover (i) investigations of the properties of spacetime singularities such as those that occur in the interior of black holes and in big bang cosmology...
November 7, 2016: Reports on Progress in Physics
Huiyun Xu, Dandan Ning, Dezhi Zhao, Yunhe Chen, Dongdong Zhao, Sumin Gu, Jean Xin Jiang, Peng Shang
Osteocytes, the most abundant cells in bone, are highly responsive to external environmental changes. We tested how Cx43 hemichannels which mediate the exchange of small molecules between cells and extracellular environment impact genome wide gene expression under conditions of abnormal gravity and magnetic field. To this end, we subjected osteocytic MLO-Y4 cells to a high magneto-gravitational environment and used microarray to examine global gene expression and a specific blocking antibody was used to assess the role of Cx43 hemichannels...
January 1, 2017: Frontiers in Bioscience (Landmark Edition)
Lixiang Zhou, Jinlu Yu, Lichao Sun, Yanwu Han, Guangming Wang
INTRODUCTION: In patients with traumatic brain injury, an effective approach for managing refractory intracranial hypertension is wide decompressive craniectomy. Postoperative hydrocephalus is a frequent complication requiring cerebrospinal fluid (CSF) diversion. PRESENTATION OF CASE: A 50-year-old male who underwent decompressive craniectomy after traumatic brain injury. He developed hydrocephalus postoperatively, and accordingly we placed a ventriculoperitoneal shunt...
October 15, 2016: International Journal of Surgery Case Reports
Kamil J Chodzyński, Omer F Eker, Axel E Vanrossomme, Daniel Ribeiro de Sousa, Grégory Coussement, Luc Vanhamme, Frank Dubois, Alain Bonafé, Bastien Chopard, Guy Courbebaisse, Karim Zouaoui Boudjeltia
Most intracranial aneurysms morphologic studies focused on characterization of size, location, aspect ratio, relationship to the surrounding vasculature and hemodynamics. However, the spatial orientation with respect to the gravity direction has not been taken into account although it could trigger various hemodynamic conditions. The present work addresses this possibility. It was divided in two parts: 1) the orientations of 18, 3D time-of-flight MRI (3D TOF MRI), scans of saccular aneurysms were analyzed. This investigation suggested that there was no privileged orientation for cerebral aneurysms...
October 18, 2016: Journal of Biomechanics
Mohamad Reza Soltanian, Mohammad Amin Amooie, Zhenxue Dai, David Cole, Joachim Moortgat
When CO2 is injected in saline aquifers, dissolution causes a local increase in brine density that can cause Rayleigh-Taylor-type gravitational instabilities. Depending on the Rayleigh number, density-driven flow may mix dissolved CO2 throughout the aquifer at fast advective time-scales through convective mixing. Heterogeneity can impact density-driven flow to different degrees. Zones with low effective vertical permeability may suppress fingering and reduce vertical spreading, while potentially increasing transverse mixing...
November 3, 2016: Scientific Reports
Jeremie Gaveau, Bastien Berret, Dora E Angelaki, Charalambos Papaxanthis
The brain has evolved an internal model of gravity to cope with life in the Earth's gravitational environment. How this internal model benefits the implementation of skilled movement has remained unsolved. One prevailing theory has assumed that this internal model is used to compensate for gravity's mechanical effects on the body, such as to maintain invariant motor trajectories. Alternatively, gravity force could be used purposely and efficiently for the planning and execution of voluntary movements, thereby resulting in direction-depending kinematics...
November 2, 2016: ELife
Weijin Guo, Jonas Hansson, Wouter van der Wijngaart
Capillary flow is a dominating liquid transport phenomenon on the micro- and nanoscale. As described at the beginning of the 20th century, the flow rate during imbibition of a horizontal capillary tube follows the Washburn equation, i.e. decreases over time and depends on the viscosity of the sample. This poses a problem for capillary driven systems that rely on a predictable flow rate and where the liquid viscosity is not precisely known. Here we introduce and successfully experimentally verify the first compact capillary pump design with a flow rate constant in time and independent of the liquid viscosity that can operate over an extended period of time...
October 31, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Brandon C Johnson, David M Blair, Gareth S Collins, H Jay Melosh, Andrew M Freed, G Jeffrey Taylor, James W Head, Mark A Wieczorek, Jeffrey C Andrews-Hanna, Francis Nimmo, James T Keane, Katarina Miljković, Jason M Soderblom, Maria T Zuber
Multiring basins, large impact craters characterized by multiple concentric topographic rings, dominate the stratigraphy, tectonics, and crustal structure of the Moon. Using a hydrocode, we simulated the formation of the Orientale multiring basin, producing a subsurface structure consistent with high-resolution gravity data from the Gravity Recovery and Interior Laboratory (GRAIL) spacecraft. The simulated impact produced a transient crater, ~390 kilometers in diameter, that was not maintained because of subsequent gravitational collapse...
October 28, 2016: Science
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