1,790 research outputs found
Poststroke depression and risk of stroke recurrence and mortality:protocol of a meta-analysis and systematic review
Introduction A number of observational studies have indicated that poststroke depression could increase the risk of stroke outcomes. There is a meta-analysis indicating that poststroke depression is a risk factor of all-cause mortality. This paper reports the protocol for a systematic review and meta-analysis to clarify the associations of poststroke depression with stroke recurrence and mortality in order to determine whether poststroke depression is a predictor of stroke outcomes according to data extracted from relevant observational studies.Methods and analysis MEDLINE, Web of Science databases, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews will be used to conduct the search. Published studies written in English will be included. The risk of bias for the studies included in the systematic review or meta-analysis will be assessed by the Newcastle–Ottawa Quality Assessment Scale. HRs for stroke recurrence and mortality with 95% CIs will be included as primary outcomes. Subgroup analyses and meta-regression will be performed.Ethics and dissemination Ethics approval will not be needed because the data used in this systematic review will be extracted from published studies. The results of the systematic review focusing on whether depression after stroke is a predictor for stroke recurrence and mortality will be disseminated by publication in a peer-reviewed journal.PROSPERO registration number CRD42018107944
Association between late-life depression or depressive symptoms and stroke morbidity in elders::a systematic review and meta-analysis of cohort studies
Holographic GB gravity in arbitrary dimensions
We study the properties of the holographic CFT dual to Gauss-Bonnet gravity
in general dimensions. We establish the AdS/CFT dictionary and in
particular relate the couplings of the gravitational theory to the universal
couplings arising in correlators of the stress tensor of the dual CFT. This
allows us to examine constraints on the gravitational couplings by demanding
consistency of the CFT. In particular, one can demand positive energy fluxes in
scattering processes or the causal propagation of fluctuations. We also examine
the holographic hydrodynamics, commenting on the shear viscosity as well as the
relaxation time. The latter allows us to consider causality constraints arising
from the second-order truncated theory of hydrodynamics.Comment: 48 pages, 9 figures. v2: New discussion on free fields in subsection
3.3 and new appendix B on conformal tensor fields. Added comments on the
relation between the central charge appearing in the two-point function and
the "central charge" characterizing the entropy density in the discussion.
References adde
#WuhanDiary and #WuhanLockdown: gendered posting patterns and behaviours on Weibo during the COVID-19 pandemic
Social media can be both a source of information and misinformation during health emergencies. During the COVID-19 pandemic, social media became a ubiquitous tool for people to communicate and represents a rich source of data researchers can use to analyse users' experiences, knowledge and sentiments. Research on social media posts during COVID-19 has identified, to date, the perpetuity of traditional gendered norms and experiences. Yet these studies are mostly based on Western social media platforms. Little is known about gendered experiences of lockdown communicated on non-Western social media platforms. Using data from Weibo, China's leading social media platform, we examine gendered user patterns and sentiment during the first wave of the pandemic between 1 January 2020 and 1 July 2020. We find that Weibo posts by self-identified women and men conformed with some gendered norms identified on other social media platforms during the COVID-19 pandemic (posting patterns and keyword usage) but not all (sentiment). This insight may be important for targeted public health messaging on social media during future health emergencies
Laser-induced etching of few-layer graphene synthesized by Rapid-Chemical Vapour Deposition on Cu thin films
The outstanding electrical and mechanical properties of graphene make it very
attractive for several applications, Nanoelectronics above all. However a
reproducible and non destructive way to produce high quality, large-scale area,
single layer graphene sheets is still lacking. Chemical Vapour Deposition of
graphene on Cu catalytic thin films represents a promising method to reach this
goal, because of the low temperatures (T < 900 Celsius degrees) involved during
the process and of the theoretically expected monolayer self-limiting growth.
On the contrary such self-limiting growth is not commonly observed in
experiments, thus making the development of techniques allowing for a better
control of graphene growth highly desirable. Here we report about the local
ablation effect, arising in Raman analysis, due to the heat transfer induced by
the laser incident beam onto the graphene sample.Comment: v1:9 pages, 8 figures, submitted to SpringerPlus; v2: 11 pages,
PDFLaTeX, 9 figures, revised peer-reviewed version resubmitted to
SpringerPlus; 1 figure added, figure 1 and 4 replaced,typos corrected,
"Results and discussion" section significantly extended to better explain
etching mechanism and features of Raman spectra, references adde
Nonlinear Hydrodynamics from Flow of Retarded Green's Function
We study the radial flow of retarded Green's function of energy-momentum
tensor and -current of dual gauge theory in presence of generic higher
derivative terms in bulk Lagrangian. These are first order non-linear Riccati
equations. We solve these flow equations analytically and obtain second order
transport coefficients of boundary plasma. This way of computing transport
coefficients has an advantage over usual Kubo approach. The non-linear equation
turns out to be a linear first order equation when we study the Green's
function perturbatively in momentum. We consider several examples including
term and generic four derivative terms in bulk. We also study the flow
equations for -charged black holes and obtain exact expressions for second
order transport coefficients for dual plasma in presence of arbitrary chemical
potentials. Finally we obtain higher derivative corrections to second order
transport coefficients of boundary theory dual to five dimensional gauge
supergravity.Comment: Version 2, reference added, typos correcte
Holographic Charged Fluid with Anomalous Current at Finite Cutoff Surface in Einstein-Maxwell Gravity
The holographic charged fluid with anomalous current in Einstein-Maxwell
gravity has been generalized from the infinite boundary to the finite cutoff
surface by using the gravity/fluid correspondence. After perturbing the boosted
Reissner-Nordstrom (RN)-AdS black brane solution of the Einstein-Maxwell
gravity with the Chern-Simons term, we obtain the first order perturbative
gravitational and Maxwell solutions, and calculate the stress tensor and
charged current of the dual fluid at finite cutoff surfaces which contains
undetermined parameters after demanding regularity condition at the future
horizon. We adopt the Dirichlet boundary condition and impose the Landau frame
to fix these parameters, finally obtain the dependence of transport
coefficients in the dual stress tensor and charged current on the arbitrary
radical cutoff . We find that the dual fluid is not conformal, but it has
vanishing bulk viscosity, and the shear viscosity to entropy density ratio is
universally . Other transport coefficients of the dual current turns
out to be cutoff-dependent. In particular, the chiral vortical conductivity
expressed in terms of thermodynamic quantities takes the same form as that of
the dual fluid at the asymptotic AdS boundary, and the chiral magnetic
conductivity receives a cutoff-dependent correction which vanishes at the
infinite boundary.Comment: 19 pages, v2: references added, v3: typos corrected, v5: typos
corrected, version accepted for publication in JHE
Thermodynamic analysis of black hole solutions in gravitating nonlinear electrodynamics
We perform a general study of the thermodynamic properties of static
electrically charged black hole solutions of nonlinear electrodynamics
minimally coupled to gravitation in three space dimensions. The Lagrangian
densities governing the dynamics of these models in flat space are defined as
arbitrary functions of the gauge field invariants, constrained by some
requirements for physical admissibility. The exhaustive classification of these
theories in flat space, in terms of the behaviour of the Lagrangian densities
in vacuum and on the boundary of their domain of definition, defines twelve
families of admissible models. When these models are coupled to gravity, the
flat space classification leads to a complete characterization of the
associated sets of gravitating electrostatic spherically symmetric solutions by
their central and asymptotic behaviours. We focus on nine of these families,
which support asymptotically Schwarzschild-like black hole configurations, for
which the thermodynamic analysis is possible and pertinent. In this way, the
thermodynamic laws are extended to the sets of black hole solutions of these
families, for which the generic behaviours of the relevant state variables are
classified and thoroughly analyzed in terms of the aforementioned boundary
properties of the Lagrangians. Moreover, we find universal scaling laws (which
hold and are the same for all the black hole solutions of models belonging to
any of the nine families) running the thermodynamic variables with the electric
charge and the horizon radius. These scale transformations form a one-parameter
multiplicative group, leading to universal "renormalization group"-like
first-order differential equations. The beams of characteristics of these
equations generate the full set of black hole states associated to any of these
gravitating nonlinear electrodynamics...Comment: 51 single column pages, 19 postscript figures, 2 tables, GRG tex
style; minor corrections added; final version appearing in General Relativity
and Gravitatio
Direct Measurement of Nuclear Dependence of Charged Current Quasielastic-like Neutrino Interactions using MINERvA
Charged-current interactions on carbon, iron, and lead with a
final state hadronic system of one or more protons with zero mesons are used to
investigate the influence of the nuclear environment on quasielastic-like
interactions. The transfered four-momentum squared to the target nucleus,
, is reconstructed based on the kinematics of the leading proton, and
differential cross sections versus and the cross-section ratios of iron,
lead and carbon to scintillator are measured for the first time in a single
experiment. The measurements show a dependence on atomic number. While the
quasielastic-like scattering on carbon is compatible with predictions, the
trends exhibited by scattering on iron and lead favor a prediction with
intranuclear rescattering of hadrons accounted for by a conventional particle
cascade treatment. These measurements help discriminate between different
models of both initial state nucleons and final state interactions used in the
neutrino oscillation experiments
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