965 research outputs found
Thermodynamic Geometry of the Born-Infeld-anti-de Sitter black holes
Thermodynamic geometry is applied to the Born-Infeld-anti-de Sitter black
hole (BIAdS) in the four dimensions, which is a nonlinear generalization of the
Reissner-Norstr\"Aom-AdS black hole (RNAdS). We compute the Weinhold as well as
the Ruppeiner scalar curvature and find that the singular points are not the
same with the ones obtained using the heat capacity. Legendre-invariant metric
proposed by Quevedo and the metric obtained by using the free energy as the
thermodynamic potential are obtained and the corresponding scalar curvatures
diverge at the Davies points.Comment: Latex,19 pages,14 figure
Phase transition and scaling behavior of topological charged black holes in Horava-Lifshitz gravity
Gravity can be thought as an emergent phenomenon and it has a nice
"thermodynamic" structure. In this context, it is then possible to study the
thermodynamics without knowing the details of the underlying microscopic
degrees of freedom. Here, based on the ordinary thermodynamics, we investigate
the phase transition of the static, spherically symmetric charged black hole
solution with arbitrary scalar curvature in Ho\v{r}ava-Lifshitz gravity at
the Lifshitz point . The analysis is done using the canonical ensemble
frame work; i.e. the charge is kept fixed. We find (a) for both and
, there is no phase transition, (b) while case exhibits the second
order phase transition within the {\it physical region} of the black hole. The
critical point of second order phase transition is obtained by the divergence
of the heat capacity at constant charge. Near the critical point, we find the
various critical exponents. It is also observed that they satisfy the usual
thermodynamic scaling laws.Comment: Minor corrections, refs. added, to appear in Class. Quant. Grav.
arXiv admin note: text overlap with arXiv:1111.0973 by other author
Role of plasminogen activator inhibitor type 1 (PAI-1) in PCOS patient
Background: There has been few studies done demonstrating elevated level of PAI-1 in women with Polycystic Ovarian Syndrome (PCOS). PAI-1 has been associated with insulin resistance, obesity, anovulatory infertility, increased risk of cardiovascular disease in PCOS patient. The objective of the study was to find out the plasma level of PAI-1 in PCOS and compare with healthy age matched control. To correlate PAI-1 with various demographic, anthropometric, biochemical and hormonal parameters in PCOS patient and specific relation of PAI-1 with the insulin resistance, obesity, hyperandrogenemia.Methods: A prospective case control study was carried out in 50 patients having PCOS (fulfilling Rotterdam Criteria, 2003). 25 healthy age matched control were taken. Blood samples were taken for estimation of fasting glucose, fasting insulin, lipid profile, LH, FSH, Prolactin, Testosterone, insulin sensitive indices (HOMA-IR, glucose: insulin ratio). Plasma level of PAI-1 was estimated with Human ELISA invitorgen kit. The data were statistically analysed with SPSS 16.0 version (student T test, Pearson ranked correlation coefficient, linear regression analysis was applied) and PAI-1 was correlated with various parameters.Results: Mean level of PAI-1 was significantly raised in PCOS patient (893.36±234.97) pg/mL than in control (259.68±97.75) pg/mL (p<0.001). PAI-1 significantly correlated with insulin resistance, obesity; that is; PAI-1 significantly correlated with BMI (r=0.557; p<0.001), waist: hip ratio (r=0.550; p<0.001), fasting glucose (r=0.429; p=0.002), fasting insulin (r=0.357; p=0.001), triglyceride (r=0.492; p=0.000), LDL (r=0.604; p=0.001), HOMA-IR (r=0.467; p=0.001). On regression analysis LDL, fasting insulin, HOMA-IR altogether explained 54.9% of total variability of PAI-1.Conclusions: Plasma level of PAI-1 is elevated in PCOS patient and it is significantly correlated with insulin resistance and obesity
Matching of the continuous gravitational wave in an all sky search
We investigate the matching of continuous gravitational wave (CGW) signals in
an all sky search with reference to Earth based laser interferometric
detectors. We consider the source location as the parameters of the signal
manifold and templates corresponding to different source locations. It has been
found that the matching of signals from locations in the sky that differ in
their co-latitude and longitude by radians decreases with source
frequency. We have also made an analysis with the other parameters affecting
the symmetries. We observe that it may not be relevant to take care of the
symmetries in the sky locations for the search of CGW from the output of
LIGO-I, GEO600 and TAMA detectors.Comment: 16 pages, 7 figures, 3 Tables, To appear in Int. J. Mod. Phys.
Alkane-modified short polyethyleneimine for siRNA delivery
RNA interference (RNAi) is a highly specific gene-silencing mechanism triggered by small interfering RNA (siRNA). Effective intracellular delivery requires the development of potent siRNA carriers. Here, we describe the synthesis and screening of a series of siRNA delivery materials. Short polyethyleneimine (PEI, Mw 600) was selected as a cationic backbone to which lipid tails were conjugated at various levels of saturation. In solution these polymer–lipid hybrids self-assemble to form nanoparticles capable of complexing siRNA. The complexes silence genes specifically and with low cytotoxicity. The efficiency of gene knockdown increased as the number of lipid tails conjugated to the PEI backbone increased. This is explained by reducing the binding affinity between the siRNA strands to the complex, thereby enabling siRNA release after cellular internalization. These results highlight the importance of complexation strength when designing siRNA delivery materials.Misrock FoundationAmerican Society for Engineering Education. National Defense Science and Engineering Graduate FellowshipNational Institutes of Health (U.S) (Grant EB000244)National Cancer Institute (U.S.) (MIT-Harvard Center of Cancer Nanotechnology Excellence. Grant CA151884)National Science Foundation (U.S.)Massachusetts Institute of Technology (Presidential Fellowships
Secondary organic aerosol production from diesel vehicle exhaust: impact of aftertreatment, fuel chemistry and driving cycle
Environmental chamber ("smog chamber") experiments were conducted to
investigate secondary organic aerosol (SOA) production from dilute emissions
from two medium-duty diesel vehicles (MDDVs) and three heavy-duty diesel
vehicles (HDDVs) under urban-like conditions. Some of the vehicles were
equipped with emission control aftertreatment devices, including diesel
particulate filters (DPFs), selective catalytic reduction (SCR) and diesel
oxidation catalysts (DOCs). Experiments were also performed with different
fuels (100% biodiesel and low-, medium- or high-aromatic ultralow sulfur
diesel) and driving cycles (Unified Cycle,~Urban Dynamometer Driving
Schedule, and creep + idle). During normal operation, vehicles with a
catalyzed DPF emitted very little primary particulate matter (PM).
Furthermore, photooxidation of dilute emissions from these vehicles produced
essentially no SOA (below detection limit). However, significant primary PM
emissions and SOA production were measured during active DPF regeneration
experiments. Nevertheless, under reasonable assumptions about DPF
regeneration frequency, the contribution of regeneration emissions to the
total vehicle emissions is negligible, reducing PM trapping efficiency by
less than 2%. Therefore, catalyzed DPFs appear to be very effective in
reducing both primary PM emissions and SOA production from diesel vehicles.
For both MDDVs and HDDVs without aftertreatment substantial SOA formed in the
smog chamber – with the emissions from some vehicles generating twice as
much SOA as primary organic aerosol after 3 h of oxidation at typical
urban VOC / NO<sub>x</sub> ratios (3 : 1). Comprehensive organic gas
speciation was performed on these emissions, but less than half of the
measured SOA could be explained by traditional (speciated) SOA precursors.
The remainder presumably originates from the large fraction (~30%) of
the nonmethane organic gas emissions that could not be speciated using
traditional one-dimensional gas chromatography. The unspeciated organics –
likely comprising less volatile species such as intermediate volatility
organic compounds – appear to be important SOA precursors; we estimate that
the effective SOA yield (defined as the ratio of SOA mass to reacted
precursor mass) was 9 ± 6% if both speciated SOA precursors and
unspeciated organics are included in the analysis. SOA production from creep
+ idle operation was 3–4 times larger than SOA production from the same
vehicle operated over the Urban Dynamometer Driving Schedule (UDDS). Fuel
properties had little or no effect on primary PM emissions or SOA formation
Retrograde semaphorin-plexin signalling drives homeostatic synaptic plasticity.
Homeostatic signalling systems ensure stable but flexible neural activity and animal behaviour. Presynaptic homeostatic plasticity is a conserved form of neuronal homeostatic signalling that is observed in organisms ranging from Drosophila to human. Defining the underlying molecular mechanisms of neuronal homeostatic signalling will be essential in order to establish clear connections to the causes and progression of neurological disease. During neural development, semaphorin-plexin signalling instructs axon guidance and neuronal morphogenesis. However, semaphorins and plexins are also expressed in the adult brain. Here we show that semaphorin 2b (Sema2b) is a target-derived signal that acts upon presynaptic plexin B (PlexB) receptors to mediate the retrograde, homeostatic control of presynaptic neurotransmitter release at the neuromuscular junction in Drosophila. Further, we show that Sema2b-PlexB signalling regulates presynaptic homeostatic plasticity through the cytoplasmic protein Mical and the oxoreductase-dependent control of presynaptic actin. We propose that semaphorin-plexin signalling is an essential platform for the stabilization of synaptic transmission throughout the developing and mature nervous system. These findings may be relevant to the aetiology and treatment of diverse neurological and psychiatric diseases that are characterized by altered or inappropriate neural function and behaviour
Geo-environmental mapping using physiographic analysis: constraints on the evaluation of land instability and groundwater pollution hazards in the Metropolitan District of Campinas, Brazil
Geo-environmental terrain assessments and territorial zoning are useful tools for the formulation and implementation of environmental management instruments (including policy-making, planning, and enforcement of statutory regulations). They usually involve a set of procedures and techniques for delimitation, characterisation and classification of terrain units. However, terrain assessments and zoning exercises are often costly and time-consuming, particularly when encompassing large areas, which in many cases prevent local agencies in developing countries from properly benefiting from such assessments. In the present paper, a low-cost technique based on the analysis of texture of satellite imagery was used for delimitation of terrain units. The delimited units were further analysed in two test areas situated in Southeast Brazil to provide estimates of land instability and the vulnerability of groundwater to pollution hazards. The implementation incorporated procedures for inferring the influences and potential implications of tectonic fractures and other discontinuities on ground behaviour and local groundwater flow. Terrain attributes such as degree of fracturing, bedrock lithology and weathered materials were explored as indicators of ground properties. The paper also discusses constraints on- and limitations of- the approaches taken
Thermodynamic Geometry and Phase Transitions in Kerr-Newman-AdS Black Holes
We investigate phase transitions and critical phenomena in Kerr-Newman-Anti
de Sitter black holes in the framework of the geometry of their equilibrium
thermodynamic state space. The scalar curvature of these state space Riemannian
geometries is computed in various ensembles. The scalar curvature diverges at
the critical point of second order phase transitions for these systems.
Remarkably, however, we show that the state space scalar curvature also carries
information about the liquid-gas like first order phase transitions and the
consequent instabilities and phase coexistence for these black holes. This is
encoded in the turning point behavior and the multi-valued branched structure
of the scalar curvature in the neighborhood of these first order phase
transitions. We re-examine this first for the conventional Van der Waals
system, as a preliminary exercise. Subsequently, we study the Kerr-Newman-AdS
black holes for a grand canonical and two "mixed" ensembles and establish novel
phase structures. The state space scalar curvature bears out our assertion for
the first order phase transitions for both the known and the new phase
structures, and closely resembles the Van der Waals system.Comment: 1 + 41 pages, LaTeX, 46 figures. Discussions, clarifications and
references adde
The effects of financialisation and financial development on investment: Evidence from firm-level data in Europe
In this paper we estimate the effects of financialization on physical investment in selected western European countries using panel data based on the balance-sheets of publicly listed non-financial companies (NFCs) supplied by Worldscope for the period 1995-2015. We find robust evidence of an adverse effect of both financial payments
(interests and dividends) and financial incomes on investment in fixed assets by the NFCs. This finding is robust for both the pool of all Western European firms and single country estimations. The negative impacts of financial incomes are non-linear with respect to the companies’ size: financial incomes crowd-out investment in large companies, and have a positive effect on the investment of only small, relatively more credit-constrained companies. Moreover, we find that a higher degree of financial development is associated with a stronger negative effect of financial incomes on companies’ investment. This finding challenges the common wisdom on ‘finance-growth nexus’. Our findings support the ‘financialization thesis’ that the increasing orientation of the non-financial sector towards financial activities is ultimately leading to lower physical investment, hence to stagnant or fragile growth, as well as long term stagnation in productivity
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