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Juan Idiaquez, Juan Francisco Idiaquez, Rodrigo Iturriaga
OBJECTIVE: Arterial blood pressure (BP) increased in healthy humans in response to isometric handgrip (IHG), but the pattern of the relative contribution of cardiac output (CO) and total peripheral resistance (TPR) changes to the pressor response is different among individuals. We investigated weather patients with recurrent vasovagal syncope (VVS) have a similar pattern of individual CO, TPR and pressor responses to IHG, as healthy subjects. METHODS: 32 patients (27...
July 2018: Autonomic Neuroscience: Basic & Clinical
André L P Livorati, Tiago Kroetz, Carl P Dettmann, Iberê L Caldas, Edson D Leonel
We characterize a transition from normal to ballistic diffusion in a bouncing ball dynamics. The system is composed of a particle, or an ensemble of noninteracting particles, experiencing elastic collisions with a heavy and periodically moving wall under the influence of a constant gravitational field. The dynamics lead to a mixed phase space where chaotic orbits have a free path to move along the velocity axis, presenting a normal diffusion behavior. Depending on the control parameter, one can observe the presence of featured resonances, known as accelerator modes, that lead to a ballistic growth of velocity...
March 2018: Physical Review. E
Neil J Cornish, Logan O'Beirne, Stephen R Taylor, Nicolás Yunes
The opening of the gravitational wave window by ground-based laser interferometers has made possible many new tests of gravity, including the first constraints on polarization. It is hoped that, within the next decade, pulsar timing will extend the window by making the first detections in the nanohertz frequency regime. Pulsar timing offers several advantages over ground-based interferometers for constraining the polarization of gravitational waves due to the many projections of the polarization pattern provided by the different lines of sight to the pulsars, and the enhanced response to longitudinal polarizations...
May 4, 2018: Physical Review Letters
David E Smith, Maria T Zuber, Erwan Mazarico, Antonio Genova, Gregory A Neumann, Xiaoli Sun, Mark H Torrence, Dan-Dan Mao
The scale of the solar system is slowly changing, likely increasing as a result of solar mass loss, with additional change possible if there is a secular variation of the gravitational constant, G . The measurement of the change of scale could provide insight into the past and the future of the solar system, and in addition a better understanding of planetary motion and fundamental physics. Estimates for the expansion of the scale of the solar system are of order 1.5 cm year-1 AU-1 , which over several years is an observable quantity with present-day laser ranging systems...
April 2018: Planetary and Space Science
Massimo Zecchin, Flavio Accaino, Silvia Ceramicola, Dario Civile, Salvatore Critelli, Cristina Da Lio, Giacomo Mangano, Giacomo Prosser, Pietro Teatini, Luigi Tosi
Large-scale submarine gravitational land movements involving even more than 1,000 m thick sedimentary successions are known as megalandslides. We prove the existence of large-scale gravitational phenomena off the Crotone Basin, a forearc basin located on the Ionian side of Calabria (southern Italy), by seismic, morpho-bathymetric and well data. Our study reveals that the Crotone Megalandslide started moving between Late Zanclean and Early Piacenzian and was triggered by a contractional tectonic event leading to the basin inversion...
May 17, 2018: Scientific Reports
Takuya Hashimoto, Nicolas Laporte, Ken Mawatari, Richard S Ellis, Akio K Inoue, Erik Zackrisson, Guido Roberts-Borsani, Wei Zheng, Yoichi Tamura, Franz E Bauer, Thomas Fletcher, Yuichi Harikane, Bunyo Hatsukade, Natsuki H Hayatsu, Yuichi Matsuda, Hiroshi Matsuo, Takashi Okamoto, Masami Ouchi, Roser Pelló, Claes-Erik Rydberg, Ikkoh Shimizu, Yoshiaki Taniguchi, Hideki Umehata, Naoki Yoshida
A fundamental quest of modern astronomy is to locate the earliest galaxies and study how they influenced the intergalactic medium a few hundred million years after the Big Bang1-3 . The abundance of star-forming galaxies is known to decline4,5 from redshifts of about 6 to 10, but a key question is the extent of star formation at even earlier times, corresponding to the period when the first galaxies might have emerged. Here we report spectroscopic observations of MACS1149-JD1 6 , a gravitationally lensed galaxy observed when the Universe was less than four per cent of its present age...
May 2018: Nature
V D Burkert, L Elouadrhiri, F X Girod
The proton, one of the components of atomic nuclei, is composed of fundamental particles called quarks and gluons. Gluons are the carriers of the force that binds quarks together, and free quarks are never found in isolation-that is, they are confined within the composite particles in which they reside. The origin of quark confinement is one of the most important questions in modern particle and nuclear physics because confinement is at the core of what makes the proton a stable particle and thus provides stability to the Universe...
May 2018: Nature
Lianhui Li, Hongguang Wang
Annual power load forecasting is not only the premise of formulating reasonable macro power planning, but also an important guarantee for the safety and economic operation of power system. In view of the characteristics of annual power load forecasting, the grey model of GM (1,1) are widely applied. Introducing buffer operator into GM (1,1) to pre-process the historical annual power load data is an approach to improve the forecasting accuracy. To solve the problem of nonadjustable action intensity of traditional weakening buffer operator, variable-weight weakening buffer operator (VWWBO) and background value optimization (BVO) are used to dynamically pre-process the historical annual power load data and a VWWBO-BVO-based GM (1,1) is proposed...
2018: PloS One
James M Hill, Joseph O'Leary
We examine a static, spherically symmetric solution of the empty space field equations of general relativity with a non-orthogonal line element which gives rise to an opportunity that does not occur in the standard derivations of the Schwarzschild solution. In these derivations, convenient coordinate transformations and dynamical assumptions inevitably lead to the Schwarzschild solution. By relaxing these conditions, a new solution possibility arises and the resulting formalism embraces the Schwarzschild solution as a special case...
April 2018: Royal Society Open Science
Magda Gioia, Anna Michaletti, Manuel Scimeca, Mario Marini, Umberto Tarantino, Lello Zolla, Massimo Coletta
Decreased mechanical loading on bones, such as prolonged bed rest and microgravity during space flights, leads to the development of an osteoporotic-like phenotype. Although osteoblast hypo-functionality is reported to be involved in the progression of bone pathological conditions, the cellular mechanisms of this process remain largely unknown. The combined application of mass spectrometry "-omics" and histochemical and ultrastructural approaches have been employed to investigate the effects of the gravitational unloading on human bone-cell biology...
2018: Cell Death Discovery
C Dietz, R Bergert, B Steinmüller, M Kretschmer, S Mitic, M H Thoma
Three-dimensional plasma crystals are often described as Yukawa systems for which a phase transition between the crystal structures fcc and bcc has been predicted. However, experimental investigations of this transition are missing. We use a fast scanning video camera to record the crystallization process of 70 000 microparticles and investigate the existence of the fcc-bcc phase transition at neutral gas pressures of 30, 40, and 50 Pa. To analyze the crystal, robust phase diagrams with the help of a machine learning algorithm are calculated...
April 2018: Physical Review. E
Renato Pakter, Yan Levin
We show that stability of planetary systems is intimately connected with their internal order. An arbitrary initial distribution of planets is susceptible to catastrophic events in which planets either collide or are ejected from the planetary system. These instabilities are a fundamental consequence of chaotic dynamics and of Arnold diffusion characteristic of many body gravitational interactions. To ensure stability over astronomical time scale of a realistic planetary system-in which planets have masses comparable to those of planets in the solar system-the motion must be quasiperiodic...
April 2018: Physical Review. E
Benaoumeur Bakhti, Divana Boukari, Michael Karbach, Philipp Maass, Gerhard Müller
We consider a lattice gas in spaces of dimensionality D=1,2,3. The particles are subject to a hardcore exclusion interaction and an attractive pair interaction that satisfies Gauss' law as do Newtonian gravity in D=3, a logarithmic potential in D=2, and a distance-independent force in D=1. Under mild additional assumptions regarding symmetry and fluctuations we investigate equilibrium states of self-gravitating material clusters, in particular radial density profiles for closed and open systems. We present exact analytic results in several instances and high-precision numerical data in others...
April 2018: Physical Review. E
Yanan Guo, Miao Yu, Na Jing, Shoutao Zhang
Embryonic stem cells and induced pluripotent stem cells depend on one of cytokines called leukemia inhibitory factor (LIF) to retain their undifferentiated state and pluripotency. Nevertheless, further progresses of stem cell scientific investigation and its possible application are limited owing to the expense of commercial LIF. Here we introduced a simple, practical and high level expression of MBP-mouse LIF through Escherichia coli system which was bioactive. The mLIF cDNA was inserted into vector of pMAL-C2X in order to generate N-terminal MBP-mLIF recombinant proteins in the cytoplasm of Escherichia coli...
May 11, 2018: Protein Expression and Purification
Lionel London, Sebastian Khan, Edward Fauchon-Jones, Cecilio García, Mark Hannam, Sascha Husa, Xisco Jiménez-Forteza, Chinmay Kalaghatgi, Frank Ohme, Francesco Pannarale
Gravitational-wave observations of binary black holes currently rely on theoretical models that predict the dominant multipoles (ℓ=2,|m|=2) of the radiation during inspiral, merger, and ringdown. We introduce a simple method to include the subdominant multipoles to binary black hole gravitational waveforms, given a frequency-domain model for the dominant multipoles. The amplitude and phase of the original model are appropriately stretched and rescaled using post-Newtonian results (for the inspiral), perturbation theory (for the ringdown), and a smooth transition between the two...
April 20, 2018: Physical Review Letters
Brando Bellazzini, Francesco Riva, Javi Serra, Francesco Sgarlata
We constrain effective field theories by going beyond the familiar positivity bounds that follow from unitarity, analyticity, and crossing symmetry of the scattering amplitudes. As interesting examples, we discuss the implications of the bounds for the Galileon and ghost-free massive gravity. The combination of our theoretical bounds with the experimental constraints on the graviton mass implies that the latter is either ruled out or unable to describe gravitational phenomena, let alone to consistently implement the Vainshtein mechanism, down to the relevant scales of fifth-force experiments, where general relativity has been successfully tested...
April 20, 2018: Physical Review Letters
Carl L Rodriguez, Pau Amaro-Seoane, Sourav Chatterjee, Frederic A Rasio
We present models of realistic globular clusters with post-Newtonian dynamics for black holes. By modeling the relativistic accelerations and gravitational-wave emission in isolated binaries and during three- and four-body encounters, we find that nearly half of all binary black hole mergers occur inside the cluster, with about 10% of those mergers entering the LIGO/Virgo band with eccentricities greater than 0.1. In-cluster mergers lead to the birth of a second generation of black holes with larger masses and high spins, which, depending on the black hole natal spins, can sometimes be retained in the cluster and merge again...
April 13, 2018: Physical Review Letters
Eemeli Annala, Tyler Gorda, Aleksi Kurkela, Aleksi Vuorinen
The detection of gravitational waves originating from a neutron-star merger, GW170817, by the LIGO and Virgo Collaborations has recently provided new stringent limits on the tidal deformabilities of the stars involved in the collision. Combining this measurement with the existence of two-solar-mass stars, we generate a generic family of neutron-star-matter equations of state (EOSs) that interpolate between state-of-the-art theoretical results at low and high baryon density. Comparing the results to ones obtained without the tidal-deformability constraint, we witness a dramatic reduction in the family of allowed EOSs...
April 27, 2018: Physical Review Letters
F J Fattoyev, J Piekarewicz, C J Horowitz
The historical first detection of a binary neutron star merger by the LIGO-Virgo Collaboration [B. P. Abbott et al., Phys. Rev. Lett. 119, 161101 (2017)PRLTAO0031-900710.1103/PhysRevLett.119.161101] is providing fundamental new insights into the astrophysical site for the r process and on the nature of dense matter. A set of realistic models of the equation of state (EOS) that yield an accurate description of the properties of finite nuclei, support neutron stars of two solar masses, and provide a Lorentz covariant extrapolation to dense matter are used to confront its predictions against tidal polarizabilities extracted from the gravitational-wave data...
April 27, 2018: Physical Review Letters
Vesna Martic, Ivo Bozovic, Ivana Berisavac, Ivana Basta, Stojan Peric, Milica Babic, Sonja Lukic Rajic, Bogdan Bjelica, Olivera Stojiljkovic Tamas, Aleksandar Stojanov, Marija Grunauer, Mina Cobeljic, Nenad Komatina, Vanja Djuric, Milutin Petrovic, Balsa Vujovic, Aleksandra Dominovic Kovacevic, Gordana Djordjevic, Dejana Jovanovic, Zorica Stevic
A majority of patients with Guillain-Barré syndrome (GBS) have tendency of a good recovery. Our aim was to evaluate the outcome of the disease 1 and 3 years after GBS symptom onset. METHODS: During 2014, GBS was diagnosed in 82 patients in seven tertiary healthcare centers. Neurological follow-up was conducted in 57 (70%) patients after 1 year, and in 54 (66%) after 3 years. Functional disability was estimated according to the GBS disability scale (GDS), with a score of 0-3 indicating mild disability and a score of 4-6 indicating severe disability during acute phase, whereas a score >1 indicated poor recovery on follow-ups...
May 2018: Canadian Journal of Neurological Sciences. le Journal Canadien des Sciences Neurologiques
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