1,382 research outputs found
Comparing Poisson Sigma Model with A-model
We discuss the A-model as a gauge fixing of the Poisson Sigma Model with
target a symplectic structure. We complete the discussion in [arXiv:0706.3164],
where a gauge fixing defined by a compatible complex structure was introduced,
by showing how to recover the A-model hierarchy of observables in terms of the
AKSZ observables. Moreover, we discuss the off-shell supersymmetry of the
A-model as a residual BV symmetry of the gauge-fixed PSM action.Comment: 15 pages, one missing reference adde
Geometric quantization and non-perturbative Poisson sigma model
In this note we point out the striking relation between the conditions
arising within geometric quantization and the non-perturbative Poisson sigma
model. Starting from the Poisson sigma model, we analyze necessary requirements
on the path integral measure which imply a certain integrality condition for
the Poisson cohomology class .
The same condition was considered before by Crainic and Zhu but in a
different context.
In the case when is in the image of the sharp map we reproduce the
Vaisman's condition for prequantizable Poisson manifolds. For integrable
Poisson manifolds we show, with a different procedure than in Crainic and Zhu,
that our integrality condition implies the prequantizability of the symplectic
groupoid. Using the relation between prequantization and symplectic reduction
we construct the explicit prequantum line bundle for a symplectic groupoid.
This picture supports the program of quantization of Poisson manifold via
symplectic groupoid. At the end we discuss the case of a generic coisotropic
D-brane.Comment: 29 page
Alignment-free Genomic Analysis via a Big Data Spark Platform
Motivation: Alignment-free distance and similarity functions (AF functions,
for short) are a well established alternative to two and multiple sequence
alignments for many genomic, metagenomic and epigenomic tasks. Due to
data-intensive applications, the computation of AF functions is a Big Data
problem, with the recent Literature indicating that the development of fast and
scalable algorithms computing AF functions is a high-priority task. Somewhat
surprisingly, despite the increasing popularity of Big Data technologies in
Computational Biology, the development of a Big Data platform for those tasks
has not been pursued, possibly due to its complexity. Results: We fill this
important gap by introducing FADE, the first extensible, efficient and scalable
Spark platform for Alignment-free genomic analysis. It supports natively
eighteen of the best performing AF functions coming out of a recent hallmark
benchmarking study. FADE development and potential impact comprises novel
aspects of interest. Namely, (a) a considerable effort of distributed
algorithms, the most tangible result being a much faster execution time of
reference methods like MASH and FSWM; (b) a software design that makes FADE
user-friendly and easily extendable by Spark non-specialists; (c) its ability
to support data- and compute-intensive tasks. About this, we provide a novel
and much needed analysis of how informative and robust AF functions are, in
terms of the statistical significance of their output. Our findings naturally
extend the ones of the highly regarded benchmarking study, since the functions
that can really be used are reduced to a handful of the eighteen included in
FADE
Neuronal Activity at Synapse Resolution:Reporters and Effectors for Synaptic Neuroscience
The development of methods for the activity-dependent tagging of neurons enabled a new way to tackle the problem of engram identification at the cellular level, giving rise to groundbreaking findings in the field of memory studies. However, the resolution of activity-dependent tagging remains limited to the whole-cell level. Notably, events taking place at the synapse level play a critical role in the establishment of new memories, and strong experimental evidence shows that learning and synaptic plasticity are tightly linked. Here, we provide a comprehensive review of the currently available techniques that enable to identify and track the neuronal activity with synaptic spatial resolution. We also present recent technologies that allow to selectively interfere with specific subsets of synapses. Lastly, we discuss how these technologies can be applied to the study of learning and memory
Lie algebroids, Lie groupoids and TFT
We construct the moduli spaces associated to the solutions of equations of
motion (modulo gauge transformations) of the Poisson sigma model with target
being an integrable Poisson manifold. The construction can be easily extended
to a case of a generic integrable Lie algebroid. Indeed for any Lie algebroid
one can associate a BF-like topological field theory which localizes on the
space of algebroid morphisms, that can be seen as a generalization of flat
connections to the groupoid case. We discuss the finite gauge transformations
and discuss the corresponding moduli spaces. We consider the theories both
without and with boundaries.Comment: 21 page
Novel asleep techniques for intraoperative assessment of brain connectivity
[no abstract available
Towards equivariant Yang-Mills theory
We study four dimensional gauge theories in the context of an equivariant
extension of the Batalin-Vilkovisky (BV) formalism. We discuss the embedding of
BV Yang-Mills (YM) theory into a larger BV theory and their relation. Partial
integration in the equivariant BV setting (BV push-forward map) is performed
explicitly for the abelian case. As result, we obtain a non-local homological
generalization of the Cartan calculus and a non-local extension of the abelian
YM BV action which satisfies the equivariant master equation.Comment: 27 pages, refs added, published versio
Association between Immunosenescence, Mitochondrial Dysfunction and Frailty Syndrome in Older Adults
Aging is associated with changes in the immune system, increased inflammation and mitochondrial dysfunction. The relationship between these phenomena and the clinical phenotype of frailty is unclear. Here, we evaluated the immune phenotypes, T cell functions and mitochondrial functions of immune cells in frail and robust older subjects. We enrolled 20 frail subjects age- and gender-matched with 20 robust controls, and T cell phenotype, response to immune stimulation, cytokine production and immune cell mitochondrial function were assessed. Our results showed that numbers of CD4+ and CD8+ T cells were decreased in frail subjects, without impairment to their ratios. Memory and naïve T cells were not significantly affected by frailty, whereas the expression of CD28 but not that of ICOS was decreased in T cells from frail subjects. T cells from robust subjects produced more IL-17 after CD28 stimulation. Levels of serum cytokines were similar in frail subjects and controls. Mitochondrial bioenergetics and ATP levels were significantly lower in immune cells from frail subjects. In conclusion, we suggest that changes in T cell profiles are associated with aging rather than with frailty syndrome; however, changes in T cell response to immune stimuli and reduced mitochondrial activity in immune cells may be considered hallmarks of frailty
MicroGen: a MIAME compliant web system for microarray experiment information and workflow management
BACKGROUND: Improvements of bio-nano-technologies and biomolecular techniques have led to increasing production of high-throughput experimental data. Spotted cDNA microarray is one of the most diffuse technologies, used in single research laboratories and in biotechnology service facilities. Although they are routinely performed, spotted microarray experiments are complex procedures entailing several experimental steps and actors with different technical skills and roles. During an experiment, involved actors, who can also be located in a distance, need to access and share specific experiment information according to their roles. Furthermore, complete information describing all experimental steps must be orderly collected to allow subsequent correct interpretation of experimental results. RESULTS: We developed MicroGen, a web system for managing information and workflow in the production pipeline of spotted microarray experiments. It is constituted of a core multi-database system able to store all data completely characterizing different spotted microarray experiments according to the Minimum Information About Microarray Experiments (MIAME) standard, and of an intuitive and user-friendly web interface able to support the collaborative work required among multidisciplinary actors and roles involved in spotted microarray experiment production. MicroGen supports six types of user roles: the researcher who designs and requests the experiment, the spotting operator, the hybridisation operator, the image processing operator, the system administrator, and the generic public user who can access the unrestricted part of the system to get information about MicroGen services. CONCLUSION: MicroGen represents a MIAME compliant information system that enables managing workflow and supporting collaborative work in spotted microarray experiment production
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