1,258 research outputs found
Stock margins and the condition probability of price reversals
Does the cost of trading affect stock prices? Yes, according to the evidence in this article. The authors find that high costs seem to reduce the frequency of price reversals.Stocks ; Stock - Prices
EXPLORING THE EFFECT OF 8 WEEKS OF CANNABIDIOL ON SERUM BRAIN-DERIVED NEUROTROPHIC FACTOR
Studies have shown that cannabidiol (CBD) consumption may lead to neuroprotective effects. Brain-derived neurotrophic factor (BDNF) is a circulating biomarker of neural health and studies exploring the effects of CBD on BDNF concentrations are limited. Purpose: The purpose of this study is to determine whether a longer-term CBD intervention would significantly change BDNF concentrations in human serum. Methods: This study used a double-blind placebo-controlled design where thirty-five healthy adult participants were randomly assigned into two groups. Participants were 25.94 ± 6.5 years of age with a body weight of 72.35 ± 13.89 kg and a body fat percentage of 22.61 ± 7.95%. One group (CB, n=18) ingested a 50mg CBD gel capsule orally once a day for 8 weeks while the control group (PL, n=17) group consumed a calorie-matched placebo (PL) over the course of the same 8-week period. At pre intervention and post intervention time points, participant body size, body composition was obtained. Blood was also collected at both time points and serum was used to determine BDNF concentration using an enzyme-linked immunosorbent assay (ELISA). An ANOVA was used to determine whether there were differences at the pre-intervention time point and the way CB and PL groups responded to the intervention. Significance was set at p \u3c 0.05. Results: There were no differences between groups at the pre-intervention time points or as a result of the intervention. Mean concentrations of BDNF at the pre-intervention time point were 25.35 ± 7.3 ng/ml and 23.03 ± 5.2 ng/ml in the PL and CB groups, respectively. Conclusion: Eight weeks of daily, low-dose CBD does not improve BDNF concentrations in healthy people. Future studies may want to explore a higher dose in individuals with impaired neural health
China and the internationalisation of the sociology of contemporary work and employment
The China e-Special Issue brings together 11 articles on the sociology of contemporary work and employment in China which have been published in WES in the past two decades, highlighting the increasing frequency of submissions, and also reflecting the diversity, complexity and plurality of work and employment in the region. The foci of debates include the changing fault lines of work and employment; the changing relationships between state, employers and workers; the impact of rural to urban migration and urbanisation on the labour process and employment configurations; the interrelations between production and social reproduction and its gendered dimensions; and the need to develop established methodologies further given the changing nature of the research subject
ISW effect in Unified Dark Matter Scalar Field Cosmologies: an analytical approach
We perform an analytical study of the Integrated Sachs-Wolfe (ISW) effect
within the framework of Unified Dark Matter models based on a scalar field
which aim at a unified description of dark energy and dark matter. Computing
the temperature power spectrum of the Cosmic Microwave Background anisotropies
we are able to isolate those contributions that can potentially lead to strong
deviations from the usual ISW effect occurring in a CDM universe. This
helps to highlight the crucial role played by the sound speed in the Unified
Dark Matter models. Our treatment is completely general in that all the results
depend only on the speed of sound of the dark component and thus it can be
applied to a variety of unified models, including those which are not described
by a scalar field but relies on a single dark fluid.Comment: 15 pages, LateX file; one comment after Eq.(36) and formula (44)
added in order to underline procedure and main results. Accepted for
publication in JCAP; some typos correcte
Some Remarks on Oscillating Inflation
In a recent paper Damour and Mukhanov describe a scenario where inflation may
continue during the oscillatory phase. This effect is possible because the
scalar field spends a significant fraction of each period of oscillation on the
upper part of the potential. Such additional period of inflation could push
perturbations after the slow roll regime to observable scales. Although in this
work we show that the small region of the Damour-Mukhanov parameter q gives the
main contribution to oscillating inflation, it was not satisfactory understood
until now. Furthermore, it gives an expression for the energy density spectrum
of perturbations, which is well behaved in the whole physical range of q .Comment: 4 pages including figures caption, 3 ps-figures. To appear in Phys.
Rev.
Topological Defects Formation after Inflation on Lattice Simulation
We consider the formation of topological defects after inflation. In order to
take into account the effects of the rescattering of fluctuations, we integrate
the classical equation that describes the evolution of a complex scalar field
on the two-dimensional lattice with a slab symmetry. The growth of fluctuations
during preheating is found not to be enough for defect formation, and rather a
long stage of the rescattering of fluctuations after preheating is necessary.
We conclude that the topological defects are not formed if the breaking scale
\eta is lager than \sim (2 - 3)\times 10^{16} GeV.Comment: 7 pages, RevTex, 10 postscript figures included; version to be
published in Phys. Rev.
The Development of Equilibrium After Preheating
We present a fully nonlinear study of the development of equilibrium after
preheating. Preheating is the exponentially rapid transfer of energy from the
nearly homogeneous inflaton field to fluctuations of other fields and/or the
inflaton itself. This rapid transfer leaves these fields in a highly nonthermal
state with energy concentrated in infrared modes. We have performed lattice
simulations of the evolution of interacting scalar fields during and after
preheating for a variety of inflationary models. We have formulated a set of
generic rules that govern the thermalization process in all of these models.
Notably, we see that once one of the fields is amplified through parametric
resonance or other mechanisms it rapidly excites other coupled fields to
exponentially large occupation numbers. These fields quickly acquire nearly
thermal spectra in the infrared, which gradually propagates into higher
momenta. Prior to the formation of total equilibrium, the excited fields group
into subsets with almost identical characteristics (e.g. group effective
temperature). The way fields form into these groups and the properties of the
groups depend on the couplings between them. We also studied the onset of chaos
after preheating by calculating the Lyapunov exponent of the scalar fields.Comment: 15 pages, 23 figure
Cosmological perturbations from inhomogeneous preheating and multi-field trapping
We consider inhomogeneous preheating in a multi-field trapping model. The
curvature perturbation is generated by inhomogeneous preheating which induces
multi-field trapping at the enhanced symmetric point (ESP), and results in
fluctuation in the number of e-foldings. Instead of considering simple
reheating after preheating, we consider a scenario of shoulder inflation
induced by the trapping. The fluctuation in the number of e-foldings is
generated during this weak inflationary period, when the additional light
scalar field is trapped at the local maximum of its potential. The situation
may look similar to locked or thermal inflation or even to hybrid inflation,
but we will show that the present mechanism of generating the curvature
perturbation is very different from these others. Unlike the conventional
trapped inflationary scenario, we do not make the assumption that an ESP
appears at some unstable point on the inflaton potential. This assumption is
crucial in the original scenario, but it is not important in the multi-field
model. We also discuss inhomogeneous preheating at late-time oscillation, in
which the magnitude of the curvature fluctuation can be enhanced to accommodate
low inflationary scale.Comment: 18pages, 2 figures, to appear in JHE
Gendered dynamics of transnational social protection
Social protection refers to resources and strategies to deal with social risks, such as poverty or obligations and needs of care, which might impede the realization of life chances and well-being. Previous research has shown that migrants are particularly affected by challenges when accessing or providing social protection, because of unfamiliar welfare regulations in the immigration country and their family and friends being located in various locations, calling for an investigation of gendered dynamics in transnational spaces. In this special issue we aim to advance these vital debates by elucidating the social consequences of the articulation and organization of formal and informal social protection across borders for different actors involved through a joint investigation of gender and transnationality as key dimensions of social inequality
- …