172 research outputs found
Interacting agegraphic dark energy models in phase space
Agegraphic dark energy, has been recently proposed, based on the so-called
Karolyhazy uncertainty relation, which arises from quantum mechanics together
with general relativity. In the first part of the article we study the original
agegraphic dark energy model by including the interaction between agegraphic
dark energy and pressureless (dark) matter. The phase space analysis was made
and the critical points were found, one of which is the attractor corresponding
to an accelerated expanding Universe.
Recent observations of near supernova show that the acceleration of Universe
decreases. This phenomenon is called the transient acceleration. In the second
part of Article we consider the 3-component Universe composed of a scalar
field, interacting with the dark matter on the agegraphic dark energy
background. We show that the transient acceleration appears in frame of such a
model. The obtained results agree with the observations.Comment: 15 pages, 5 figures, 2 table
The Holographic Model of Dark Energy and Thermodynamics of Non-Flat Accelerated Expanding Universe
Motivated by recent results on non-vanishing spatial curvature \cite{curve}
we employ the holographic model of dark energy to investigate the validity of
first and second laws of thermodynamics in non-flat (closed) universe enclosed
by apparent horizon and the event horizon measured from the sphere of
horizon named . We show that for the apparent horizon the first law is
roughly respected for different epochs while the second laws of thermodynamics
is respected while for as the system's IR cut-off first law is broken down
and second law is respected for special range of deceleration parameter. It is
also shown that at late-time universe is equal to and the
thermodynamic laws are hold, when the universe has non-vanishing curvature.
Defining the fluid temperature to be proportional to horizon temperature the
range for coefficient of proportionality is obtained provided that the
generalized second law of thermodynamics is hold.Comment: 12 pages, no figure, abstract and text extended, references added,
accepted for publication in JCA
Interacting holographic dark energy model and generalized second law of thermodynamics in non-flat universe
In the present paper we consider the interacting holographic model of dark
energy to investigate the validity of the generalized second laws of
thermodynamics in non-flat (closed) universe enclosed by the event horizon
measured from the sphere of the horizon named . We show that for as the
system's IR cut-off the generalized second law is respected for the special
range of the deceleration parameter.Comment: 11 pages, no figure
Optimized Synthesis of Solution Processable Crystalline Poly Triazine Imide with Minimized Defects for OLED Application
Poly triazine imide PTI is a highly crystallinesemiconductor, and though no techniques exist that enablesynthesis of macroscopic monolayers of PTI, it is possible tostudy it in thin layer device applications that are compatiblewith its polycrystalline, nanoscale morphology. We find that theby product of conventional PTI synthesis is a C C carbon richphase that is detrimental for charge transport and photo luminescence. An optimized synthetic protocol yields a PTImaterial with an increased quantum yield, enabled photo current and electroluminescence. We report that protonation ofthe PTI structure happens preferentially at the pyridinicN atoms of the triazine rings, is accompanied by exfoliationof PTI layers, and contributes to increases in quantum yieldand exciton lifetimes. This study describes structure propertyrelationships in PTI that link the nature of defects, theirformation, and how to avoid them with the optical andelectronic performance of PTI. On the basis of our findings, wecreate an OLED prototype with PTI as the active, metal freemateria
Self assembly and photoinduced fabrication of conductive nanographene wires on boron nitride
Manufacturing molecule based functional elements directly at device interfaces is a frontier in bottom up materials engineering. A longstanding challenge in the field is the covalent stabilization of pre assembled molecular architectures to afford nanodevice components. Here, we employ the controlled supramolecular self assembly of anthracene derivatives on a hexagonal boron nitride sheet, to generate nanographene wires through photo crosslinking and thermal annealing. Specifically, we demonstrate m long nanowires with an average width of 200 amp; 8201;nm, electrical conductivities of 106 amp; 8201;S amp; 8201;m amp; 8722;1 and breakdown current densities of 1011 amp; 8201;A amp; 8201;m amp; 8722;2. Joint experiments and simulations reveal that hierarchical self assembly promotes their formation and functional properties. Our approach demonstrates the feasibility of combined bottom up supramolecular templating and top down manufacturing protocols for graphene nanomaterials and interconnects, towards integrated carbon nanodevice
Weak lensing, dark matter and dark energy
Weak gravitational lensing is rapidly becoming one of the principal probes of
dark matter and dark energy in the universe. In this brief review we outline
how weak lensing helps determine the structure of dark matter halos, measure
the expansion rate of the universe, and distinguish between modified gravity
and dark energy explanations for the acceleration of the universe. We also
discuss requirements on the control of systematic errors so that the
systematics do not appreciably degrade the power of weak lensing as a
cosmological probe.Comment: Invited review article for the GRG special issue on gravitational
lensing (P. Jetzer, Y. Mellier and V. Perlick Eds.). V3: subsection on
three-point function and some references added. Matches the published versio
Safety and efficacy of ABT-089 in pediatric attention-deficit/hyperactivity disorder: results from two randomized placebo-controlled clinical trials.
OBJECTIVE: To assess the safety and efficacy of ABT-089, a novel α(4)β(2) neuronal nicotinic receptor partial agonist, vs. placebo in children with attention-deficit/hyperactivity disorder (ADHD).
METHOD: Two multicenter, randomized, double-blind, placebo-controlled, parallel-group studies of children 6 through 12 years of age were conducted. Study 1 (n = 274) assessed six treatment groups over 8 weeks: 4 once-daily (QD) ABT-089 doses (0.085-0.700 mg/kg), QD atomoxetine, and placebo. Study 2 (n = 119) assessed three treatment groups over 6 weeks: 2 QD ABT-089 doses (0.7 mg/kg, 1.4 mg/kg) and placebo. The primary efficacy variable was the investigator-administered Attention-Deficit/Hyperactivity Disorder Rating Scale-IV: Home Version (ADHD-RS-IV [HV]) Total Score. Safety was assessed by adverse event (AE) monitoring, laboratory tests, vital signs, physical examinations, and electrocardiogram measures.
RESULTS: There was no statistically significant difference between ABT-089 and placebo in mean change from baseline to final evaluation of ADHD-RS-IV (HV) Total Score or other outcome measures at any dose in either study. In Study 1, atomoxetine showed statistically significant improvement for the primary and most secondary endpoints. ABT-089 was generally safe and well tolerated, with no statistically significant difference between any ABT-089 dose and placebo in the overall incidence of any specific AE, and no clinically significant changes in other safety measures.
CONCLUSIONS: ABT-089 did not show efficacy on the primary efficacy variable, the ADHD-RS-IV (HV) Total Score, or other measures of ADHD symptomatology in children with ADHD, and had a safety profile similar to placebo. These results contrast with published reports of efficacy of nicotinic modulators in adults with ADHD
Cosmic Dynamics in Gravity
In this paper we consider FRW cosmology in gravity. It is shown
that in particular cases the bouncing behavior may appears in the model whereas
the equation of state (EoS) parameter may crosses the phantom divider. For the
dynamical universe, quantitatively we also find parameters in the model which
satisfies two independent tests:the model independent Cosmological Redshift
Drift (CRD) test and the type Ia supernova luminosity distances.Comment: 15 pages, 12 figure
Fluid challenges in intensive care: the FENICE study A global inception cohort study
Fluid challenges (FCs) are one of the most commonly used therapies in critically ill patients and represent the cornerstone of hemodynamic management in intensive care units. There are clear benefits and harms from fluid therapy. Limited data on the indication, type, amount and rate of an FC in critically ill patients exist in the literature. The primary aim was to evaluate how physicians conduct FCs in terms of type, volume, and rate of given fluid; the secondary aim was to evaluate variables used to trigger an FC and to compare the proportion of patients receiving further fluid administration based on the response to the FC.This was an observational study conducted in ICUs around the world. Each participating unit entered a maximum of 20 patients with one FC.2213 patients were enrolled and analyzed in the study. The median [interquartile range] amount of fluid given during an FC was 500 ml (500-1000). The median time was 24 min (40-60 min), and the median rate of FC was 1000 [500-1333] ml/h. The main indication for FC was hypotension in 1211 (59 %, CI 57-61 %). In 43 % (CI 41-45 %) of the cases no hemodynamic variable was used. Static markers of preload were used in 785 of 2213 cases (36 %, CI 34-37 %). Dynamic indices of preload responsiveness were used in 483 of 2213 cases (22 %, CI 20-24 %). No safety variable for the FC was used in 72 % (CI 70-74 %) of the cases. There was no statistically significant difference in the proportion of patients who received further fluids after the FC between those with a positive, with an uncertain or with a negatively judged response.The current practice and evaluation of FC in critically ill patients are highly variable. Prediction of fluid responsiveness is not used routinely, safety limits are rarely used, and information from previous failed FCs is not always taken into account
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