118 research outputs found
SU(2) gauge theory of gravity with topological invariants
The most general gravity Lagrangian in four dimensions contains three
topological densities, namely Nieh-Yan, Pontryagin and Euler, in addition to
the Hilbert-Palatini term. We set up a Hamiltonian formulation based on this
Lagrangian. The resulting canonical theory depends on three parameters which
are coefficients of these terms and is shown to admit a real SU(2) gauge
theoretic interpretation with a set of seven first-class constraints. Thus, in
addition to the Newton's constant, the theory of gravity contains three
(topological) coupling constants, which might have non-trivial imports in the
quantum theory.Comment: Based on a talk at Loops-11, Madrid, Spain; To appear in Journal of
Physics: Conference Serie
Quantum realizations of Hilbert-Palatini second-class constraints
In a classical theory of gravity, the Barbero-Immirzi parameter ()
appears as a topological coupling constant through the Lagrangian density
containing the Hilbert-Palatini term and the Nieh-Yan invariant. In a quantum
framework, the topological interpretation of can be captured through a
rescaling of the wavefunctional representing the Hilbert-Palatini theory, as in
the case of the QCD vacuum angle. However, such a rescaling cannot be realized
for pure gravity within the standard (Dirac) quantization procedure where the
second-class constraints of Hilbert-Palatini theory are eliminated beforehand.
Here we present a different treatment of the Hilbert-Palatini second-class
constraints in order to set up a general rescaling procedure (a) for gravity
with or without matter and (b) for any choice of gauge (e.g. time gauge). The
analysis is developed using the Gupta-Bleuler and the coherent state
quantization methods.Comment: Published versio
Use of Matrix-Pencil Method for Efficient Islanding Detection in Static DG and a Parallel Comparison With DWT Method
Islanding or nonislanding events in grid-connected distributed generation bring along a typical distinguishable transient signature in its frequency profile. This demarcation leads to the development of a new islanding protection approach, which is based on the estimation of frequency waveform parameter (transient\u27s frequency) by Matrix pencil (MP) method. To demonstrate the efficacy of the proposed MP method, four critical scenarios are considered in this paper for covering all possible disturbance events. These events are also compared along with a discrete wavelet transform (DWT) based islanding detection method in simulations as well as in RT-LAB-based real-time environment. It is noteworthy to mention that the proposed MP method has been found to have a positive edge over the DWT-based method in terms of robustness and chances of misidentification
Inflation with General Initial Conditions for Scalar Perturbations
We explore the possibility of a single field quasi-de Sitter inflationary
model with general initial state for primordial fluctuations. In this paper,
first we compute the power spectrum and the bispectrum of scalar perturbations
with coherent state as the initial state. We find that a large class of
coherent states are indistinguishable from the Bunch-Davies vacuum state and
hence consistent with the current observations. In case of a more general
initial state built over Bunch-Davies vacuum state, we show that the
constraints on the initial state from observed power spectrum and local
bispectrum are relatively weak and for quasi-de Sitter inflation a large number
of initial states are consistent with the current observations. However,
renormalizability of the energy-momentum tensor of the fluctuations constraints
the initial state further.Comment: Updated to match published version, 20 page
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PPARα-targeted mitochondrial bioenergetics mediate repair of intestinal barriers at the host-microbe intersection during SIV infection.
Chronic gut inflammatory diseases are associated with disruption of intestinal epithelial barriers and impaired mucosal immunity. HIV-1 (HIV) causes depletion of mucosal CD4+ T cells early in infection and disruption of gut epithelium, resulting in chronic inflammation and immunodeficiency. Although antiretroviral therapy (ART) is effective in suppressing viral replication, it is incapable of restoring the "leaky gut," which poses an impediment for HIV cure efforts. Strategies are needed for rapid repair of the epithelium to protect intestinal microenvironments and immunity in inflamed gut. Using an in vivo nonhuman primate intestinal loop model of HIV/AIDS, we identified the pathogenic mechanism underlying sustained disruption of gut epithelium and explored rapid repair of gut epithelium at the intersection of microbial metabolism. Molecular, immunological, and metabolomic analyses revealed marked loss of peroxisomal proliferator-activated receptor-α (PPARα) signaling, predominant impairment of mitochondrial function, and epithelial disruption both in vivo and in vitro. To elucidate pathways regulating intestinal epithelial integrity, we introduced probiotic Lactobacillus plantarum into Simian immunodeficiency virus (SIV)-inflamed intestinal lumen. Rapid recovery of the epithelium occurred within 5 h of L. plantarum administration, independent of mucosal CD4+ T cell recovery, and in the absence of ART. This intestinal barrier repair was driven by L. plantarum-induced PPARα activation and restoration of mitochondrial structure and fatty acid β-oxidation. Our data highlight the critical role of PPARα at the intersection between microbial metabolism and epithelial repair in virally inflamed gut and as a potential mitochondrial target for restoring gut barriers in other infectious or gut inflammatory diseases
Trend of Entamoeba histolytica infestation in Kolkata
Background:
Entamoeba histolytica infection is found almost all over the world and is highly endemic and a major cause of parasitic diarrhoea particularly in the developing countries.
Methods:
A systemic surveillance was set up at the Infectious Disease hospital, Kolkata, India between November 2007 and October 2009 for understanding the trend of E. histolytica infection in Kolkata. Fecal samples were collected from diarrhoeal patients attending the hospital, under the surveillance system and processed for detection of E. histolytica.
Results:
During the last two years about 2500 diarrhoeal samples were collected and screened for E. histolytica. About 3.6% were positive for E. histolytica. As compared to the earlier years, E. histolytica infection was observed to be less amongst patients screened during the last two years. No seasonality was observed in Kolkata although in the neighboring tropical country Bangladesh, a typical seasonality of E. histolytica infection was noticed.
Conclusion:
The study indicates that the detection rate of E. histolytica infection amongst diarrhoeal patients in Kolkata is decreasing during the last two years than that of Bangladesh
Examining the Experience of Teen-to-Teen Crisis Line Work for Adolescent Volunteers: A Pilot Study
Suicidal thoughts and behaviors are high and increasing among youth. Crisis lines are one of the oldest downstream approaches for suicide prevention, which have demonstrated effectiveness for adults and preliminary effectiveness for youth. Teen-to-teen (t2t) crisis lines are a unique resource where adolescent volunteers help their similarly aged peers (through texts, chats, calls, and emails). However, no research to date has examined the impacts of t2t crisis line volunteering on the youth. The goal of this pilot study is to begin to evaluate the experience of t2t crisis lines for the youth volunteers. Adolescent (n=20, ages 15-20) volunteers were recruited from two of the largest crisis lines in the U.S. – Teen Line and YouthLine. Enrolled volunteers were administered surveys assessing positive/helpful experiences, negative/unhelpful experiences, and motivations for joining the t2t crisis line. Volunteers were assessed up to five times over the course of one year; once at baseline and then every three months for up to one year (baseline, 3-month follow-up, 6-month follow-up, 9-month follow-up, 12-month/1-year follow-up). Direct content analysis was used to examine the experiences and motivations of volunteering on the crisis line. Preliminary results indicate that all volunteers reported some positive aspects of the t2t line experience, and many reported some negative aspects as well.https://digitalcommons.odu.edu/gradposters2023_sciences/1011/thumbnail.jp
Seed yield increase in Niger crop in to relation to honeybee and other pollinators
Niger (Guizotia abyssinica
Cass) is an important minor oilseed crop of
hilly and tribal regions and it is used for oil
as well as for various other purposes only by
the tribal people. Therefore, a systematic
study was arranged to document about the
increase in the seed yield of niger crop in
relation to honeybees (Aphis mellifera), as a
pollinator in niger crop with paired plot
technique at the Niger Research Station
(NRS) at Navsari Agricultural University
(NAU) and at farmer’s field, Vanarasi,
Navsari, Gujarat (India) and also studied its
relation in terms of cost benefit ratio (CB).
The trial was conducted at Niger Research
Station (NRS), Vanarasi for 3 years (2013-
14, 2014-15 and 2015-16) and also at
farmer's field to ascertain the role and
involvement of honey bees (Aphis mellifera)
in swelling the seed yield of niger crop (due
to pollination) and its effect on income due
to increase in the niger seed yield.
Significant differences were observed for
number of capitula/plant, number of
seeds/capitula, 1000 seed weight and seed
yield in both the location for the consecutive
3 years. However, the seed yield and gross
returns were considerably higher in first
location of T1 Natural plot/ open pollinated
with beehive (Aphis mellifera) in all the
3 years data with the maximum seed yield
with the gross return was obtained in this
treatment
Discovery and Optimisation of a Compound Series active against Trypanosoma cruzi, the causative agent of Chagas’ Disease
Chagas disease is caused by the protozoan parasite; Trypanosoma cruzi; . It is endemic in South and Central America and recently has been found in other parts of the world, due to migration of chronically infected patients. The current treatment for Chagas disease is not satisfactory, and there is a need for new treatments. In this work, we describe the optimization of a hit compound resulting from the phenotypic screen of a library of compounds against; T. cruzi; . The compound series was optimized to the level where it had satisfactory pharmacokinetics to allow an efficacy study in a mouse model of Chagas disease. We were able to demonstrate efficacy in this model, although further work is required to improve the potency and selectivity of this series
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