693 research outputs found
Semileptonic to Nucleon Transitions in Full QCD at Light Cone
The tree level semileptonic and
transitions are investigated using the light cone QCD sum rules approach in
full theory. The spin--1/2, baryon with or , is
considered by the most general form of its interpolating current. The time
ordering product of the initial and transition currents is expanded in terms of
the nucleon distribution amplitudes with different twists. Considering two sets
of independent input parameters entering to the nucleon wave functions, namely,
QCD sum rules and Lattice QCD parameters, the related form factors and their
heavy quark effective theory limits are calculated and compared with the
existing predictions of other approaches. It is shown that our results satisfy
the heavy quark symmetry relations for lattice input parameters and b case
exactly and the maximum violation is for charm case and QCD sum rules input
parameters. The obtained form factors are used to compute the transition rates
both in full theory and heavy quark effective theory. A comparison of the
results on decay rate of with those predicted by other
phenomenological methods or the same method in heavy quark effective theory
with different interpolating current and distribution amplitudes of the
is also presented.Comment: 18 Pages and 16 Table
On the direction of transcription of cloned genes in Neurospora crassa.
On the direction of transcription of cloned genes in Neurospora crassa
On the Early History of Current Algebra
The history of Current Algebra is reviewed up to the appearance of the
Adler-Weisberger sum rule. Particular emphasis is given to the role current
algebra played for the historical struggle in strong interaction physics of
elementary particles between the S-matrix approach based on dispersion
relations and field theory. The question whether there are fundamental
particles or all hadrons are bound or resonant states of one another played an
important role in this struggle and is thus also regarded.Comment: 17 page
On the state of Latin American states: approaching the bicentenary
Praca recenzowana / Peer-reviewed paperWhat is the actual condition of the state in Latin America? Each contributor to
this volume has been invited to answer this question by writing an interpretative
essay from a specifically suggested angle: the origins of the state; government
and society; economic growth; society and economy; nation-building;
the indigenous population; political culture; international relations etc. It was
the contributors’ decision which particular states to focus on in order to best
illuminate the issues involved.
Our main focus in the volume is on outlining some of the processes concerning
the state now, two hundred years since the first declarations of independence.
Along the way, we tackle both theoretical and normative issues. All
the contributors to this volume share a long-cultivated multidisciplinary research
interest in Latin America but the volume also reflects our disagreement
on what we take the state to be as well as on the prevailing situation in Latin
America.
Each chapter reflects the views of its author all the way down to his choice
of British or American English. As a result all chapters reflect the authors’
views on the contemporary state of the State in Latin America, as well as – why
not say it – the authors’ identities.
The book is aimed primarily at academics and students of the humanities
and social sciences
Renormalization of the QED of second order spin 1/2 fermions
In this work we study the renormalization of the electrodynamics of spin 1/2
fermions in the Poincar\'e projector formalism which is second order in the
derivatives of the fields. We analyze the superficial degree of divergence of
the vertex functions of this theory, calculate at one-loop level the vacuum
polarization, fermion self-energy and \gamma-fermion-fermion vertex function
and the divergent piece of the one-loop contributions to the
\gamma-\gamma-fermion-fermion vertex function. It is shown that these functions
are renormalizable independently of the value of the gyromagnetic factor g
which is a free parameter of the theory. We find a photon propagator and a
running coupling constant \alpha (q^2) that depend on the value of g. The
magnetic moment form factor contains a divergence associated to g which
disappears for g=2 but in general requires the coupling g to be renormalized. A
suitable choice of the renormalization condition for the magnetic form factor
yields the one loop finite correction \Delta{g}=g\alpha/2\pi. For a particle
with g=2 we recover results of Dirac theory for the photon propagator, the
running of \alpha (q^2) and the one-loop corrections to the gyromagnetic
factor.Comment: 20 pages including 6 figures. Rewritten paper, results unchanged,
version accepted in PRD. Results written in terms of Passarino-Veltman scalar
integral
Combination of Caloric Restriction and a Mixed Training Protocol as an Effective Strategy to Counteract the Deleterious Effects in Trabecular Bone Microarchitecture Caused by a Diet-Induced Obesity in Sprague Dawley Rats
The association of obesity with changes in bone mass is not clear. Obese individuals tend
to have an increased bone mineral density, but other studies have shown that obesity is a major
risk factor for fractures. The mechanisms of bone response during a weight loss therapy as well
as the possible osteoprotective effect of exercise should be analyzed. The aim of this study was to
test the effects of a weight-loss program based on the combination of caloric restriction and/or a
mixed training protocol on different parameters of bone morphology and functionality in a DIO rat
model. Three stages were established over a 21-week period (obesity induction 0–12 w, weight loss
intervention 12–15 w, weight maintenance intervention 15–21 w) in 88 male Sprague Dawley rats.
Bone microarchitecture, total mineral and elemental composition, and bone metabolism parameters
were assessed. Weight loss interventions were associated to healthy changes in body composition,
decreasing body fat and increasing lean body mass. On the other hand, obesity was related to a
higher content of bone resorption and inflammatory markers, which was decreased by the weight
control interventions. Caloric restriction led to marked changes in trabecular microarchitecture, with a
significant decrease in total volume but no changes in bone volume (BV). In addition, the intervention
diet caused an increase in trabeculae number and a decrease in trabecular spacing. The training
protocol increased the pore diameter and reversed the changes in cortical porosity and density of
BV induced by the high protein diet at diaphysis level. Regarding the weight-maintenance stage,
diminished SMI values indicate the presence of more plate-like spongiosa in sedentary and exercise
groups. In conclusion, the lifestyle interventions of caloric restriction and mixed training protocol
implemented as weight loss strategies have been effective to counteract some of the deleterious effects
caused by a dietary induction of obesity, specifically in trabecular bone morphometric parameters as
well as bone mineral content.Spanish Government DEP2014-58296-R
RTC-2017-6540-1
RTI2018-100934-B-I00Spanish Ministry of Science, Innovation and Universities through FEDER programEuropean Commission DEP2014-58296-R
RTC-2017-6540-1
RTI2018-100934-B-I00European Union through FEDER progra
Identification of a novel phosphorylation site in hepatitis C virus NS5A
Hepatitis C virus (HCV) NS5A protein is phosphorylated on multiple residues; however, despite extensive study, the precise identity of these sites has not been determined unambiguously. In this study, we have used a combination of immunoprecipitation and mass spectrometry to identify these phosphorylation sites. This analysis revealed the presence of a major phosphorylated residue within NS5A from the genotype 1b Con1 isolate – serine 249 (serine 2221 in polyprotein numbering). However, mutation of this residue (or the corresponding threonine in the JFH-1 isolate) to either a phosphomimetic (aspartate) or a phosphoablative (alanine) residue resulted in no phenotype. We conclude that phosphorylation of this residue, in the context of a highly culture-adapted HCV genome, does not play a role in either viral RNA replication or virus assembly. It is possible that it might be important in an aspect of virus biology that is not recapitulated faithfully in the Huh-7 cell-culture system
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Expanding the host range of hepatitis C virus through viral adaptation
Hepatitis C virus (HCV) species tropism is incompletely understood. We have previously shown that at the level of entry, human CD81 and occludin (OCLN) comprise the minimal set of human factors needed for viral uptake into murine cells. As an alternative approach to genetic humanization, species barriers can be overcome by adapting HCV to use the murine orthologues of these entry factors. We previously generated a murine tropic HCV (mtHCV or Jc1/mCD81) strain harboring three mutations within the viral envelope proteins that allowed productive entry into mouse cell lines. In this study, we aimed to characterize the ability of mtHCV to enter and infect mouse hepatocytes in vivo and in vitro Using a highly sensitive, Cre-activatable reporter, we demonstrate that mtHCV can enter mouse hepatocytes in vivo in the absence of any human cofactors. Viral entry still relied on expression of mouse CD81 and SCARB1 and was more efficient when mouse CD81 and OCLN were overexpressed. HCV entry could be significantly reduced in the presence of anti-HCV E2 specific antibodies, suggesting that uptake of mtHCV is dependent on viral glycoproteins. Despite mtHCV's ability to enter murine hepatocytes in vivo, we did not observe persistent infection, even in animals with severely blunted type I and III interferon signaling and impaired adaptive immune responses. Altogether, these results establish proof of concept that the barriers limiting HCV species tropism can be overcome by viral adaptation. However, additional viral adaptations will likely be needed to increase the robustness of a murine model system for hepatitis C. IMPORTANCE: At least 150 million individuals are chronically infected with HCV and are at risk of developing serious liver disease. Despite the advent of effective antiviral therapy, the frequency of chronic carriers has only marginally decreased. A major roadblock in developing a vaccine that would prevent transmission is the scarcity of animal models that are susceptible to HCV infection. It is poorly understood why HCV infects only humans and chimpanzees. To develop an animal model for hepatitis C, previous efforts focused on modifying the host environment of mice, for example, to render them more susceptible to HCV infection. Here, we attempted a complementary approach in which a laboratory-derived HCV variant was tested for its ability to infect mice. We demonstrate that this engineered HCV strain can enter mouse liver cells but does not replicate efficiently. Thus, additional adaptations are likely needed to construct a robust animal model for HCV
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