5,809 research outputs found
Coulomb Blockade in Hierarchical Quantum Hall Droplets
The degeneracy of energy levels in a quantum dot of Hall fluid, leading to
conductance peaks, can be readily derived from the partition functions of
conformal field theory. Their complete expressions can be found for Hall states
with both Abelian and non-Abelian statistics, upon adapting known results for
the annulus geometry. We analyze the Abelian states with hierarchical filling
fractions, \nu=m/(mp \pm 1), and find a non trivial pattern of conductance
peaks. In particular, each one of them occurs with a characteristic
multiplicity, that is due to the extended symmetry of the m-folded edge.
Experimental tests of the multiplicity can shed more light on the dynamics of
this composite edge.Comment: 8 pages; v2: published version; effects of level multiplicities not
well understood, see arXiv:0909.3588 for the correct analysi
Effective Field Theory and Integrability in Two-Dimensional Mott Transition
We study the Mott transition in a two-dimensional lattice spinless fermion
model with nearest neighbors density-density interactions. By means of a
two-dimensional Jordan-Wigner transformation, the model is mapped onto the
lattice XXZ spin model, which is shown to possess a Quantum Group symmetry as a
consequence of a recently found solution of the Zamolodchikov Tetrahedron
Equation. A projection (from three to two space-time dimensions) property of
the solution is used to identify the symmetry of the model at the Mott critical
point as U_q(sl(2))xU_q(sl(2)), with deformation parameter q=-1. Based on this
result, the low-energy Effective Field theory for the model is obtained and
shown to be a lattice double Chern-Simons theory with coupling constant k=1
(with the standard normalization). By further employing the Effective Filed
Theory methods, we show that the Mott transition that arises is of topological
nature, with vortices in an antiferromagnetic array and matter currents
characterized by a d-density wave order parameter. We also analyze the behavior
of the system upon weak coupling, and conclude that it undergoes a quantum
gas-liquid transition which belongs to the Ising universality class.Comment: 36 page
Secondary Effects and Public Morality
The police power consists of the authority of the state to regulate in the interests of public health, safety, and morals. As American society continues to grow more diverse and pluralistic, courts and commentators have raised concerns that the last of these, public morality, cannot serve as an acceptable justification for regulatory action. Indeed, if appeals to public morality cannot be evaluated on an objective basis, then regulators might invoke them to conceal unlawful motives. The ability of moral reasoning to provide a legitimate basis for regulation is thrown into doubt. In this Article, we examine a peculiar line of Supreme Court cases in the free speech context that bring the problem into focus. In the so-called secondary effects cases, the Justices gradually moved away from accepting public morality arguments in support of state restrictions on adult businesses. In place of public morality, the Court began to retrain its focus on the social ills attendant to the activity in question, or what it termed the ?secondary effects? of such conduct. Rather than decide whether the regulated activity is immoral, and thus within the legitimate regulatory sweep of the police power as traditionally conceived, the Court instead looked to whether the state could show that its restriction reduced deleterious secondary effects associated with the activity. This development might have appeared desirable insofar as it would permit courts to rest their rulings on objective facts rather than wrestle with matters of opinion and moral sentiment. To the contrary, we argue, secondary effects arguments rely on moral reasoning –whether articulated or not– to the same extent as public morality arguments. The Court?s attempt in the secondary effects cases to avoid engaging in moral reasoning in reality demonstrates its indispensability.Fil: Legarre, Santiago. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. University of Notre Dame-Indiana; Estados Unidos. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires"; ArgentinaFil: Mitchell, Gregory J. Notre Dame Law School; Estados Unido
Thermodynamics of a model for RNA folding
We analyze the thermodynamic properties of a simplified model for folded RNA
molecules recently studied by G. Vernizzi, H. Orland, A. Zee (in {\it Phys.
Rev. Lett.} {\bf 94} (2005) 168103). The model consists of a chain of
one-flavor base molecules with a flexible backbone and all possible pairing
interactions equally allowed. The spatial pseudoknot structure of the model can
be efficiently studied by introducing a hermitian random matrix
model at each chain site, and associating Feynman diagrams of these models to
spatial configurations of the molecules. We obtain an exact expression for the
topological expansion of the partition function of the system. We calculate
exact and asymptotic expressions for the free energy, specific heat,
entanglement and chemical potential and study their behavior as a function of
temperature. Our results are consistent with the interpretation of as
being a measure of the concentration of in solution.Comment: 11 pages, 4 figure
Drying/encapsulation of red wine to produce ingredientes for healthy foods
Epidemiological evidence indicates that moderate consumption of red wine reducesthe incidence of coronary disease, atherosclerosis, and platelet aggregation. Wine is very rich in antioxidant compounds because of their phenolic components.However, many people for ethnic, social or religious reasons do not consume wine. Drying/encapsulation of red wine in the presence of adequate carbohydrates leads to water and more than 99% of alcohol removal; a glassy amorphous microstructure is obtained in which the wine's phenolic compounds are entrapped. The resulting product is a free flowing powder which could be used for the polyphenol enrichment of healthy foods and/or drink powders, as well as in the pharmaceutical industry. The wine industry may take advantage of the dried/encapsulated red wine using as a raw material red wines which have littlecommercial value for different reasons; i.e. poor quality due to raw material, unfavourable climatic conditions, or wines that suffered some alteration during the wine making process. Dry encapsulated wine may be a new alternative to red wines that cannot be sold as such for different reasons, and open new opportunities to diversify wine products.Fil: Alvarez Gaona, Izmari Jasel. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires"; ArgentinaFil: Rocha Parra, Diego Fernando. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires"; ArgentinaFil: Zamora, MarÃa Clara. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires"; ArgentinaFil: Chirife, Jorge. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires"; Argentin
Neuroprotection targeting protein misfolding on chronic cerebral hypoperfusion in the context of metabolic syndrome
Metabolic syndrome (MetS) is a cluster of risk factors that lead to microvascular dysfunction and chronic cerebral hypoperfusion (CCH). Long-standing reduction in oxygen and energy supply leads to brain hypoxia and protein misfolding, thereby linking CCH to Alzheimer's disease. Protein misfolding results in neurodegeneration as revealed by studying different experimental models of CCH. Regulating proteostasis network through pathways like the unfolded protein response (UPR), the ubiquitin-proteasome system (UPS), chaperone-mediated autophagy (CMA), and macroautophagy emerges as a novel target for neuroprotection. Lipoxin A4 methyl ester, baclofen, URB597, N-stearoyl-L-tyrosine, and melatonin may pose potential neuroprotective agents for rebalancing the proteostasis network under CCH. Autophagy is one of the most studied pathways of proteostatic cell response against the decrease in blood supply to the brain though the role of the UPR-specific chaperones and the UPS system in CCH deserves further research. Pharmacotherapy targeting misfolded proteins at different stages in the proteostatic pathway might be promising in treating cognitive impairment following CCH.Fil: Herrera, MarÃa Inés. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; Argentina. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires". Facultad de PsicologÃa y PsicopedagogÃa; ArgentinaFil: Udovin, Lucas. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; ArgentinaFil: Toro Urrego, Nicolás. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; ArgentinaFil: Kusnier, Carlos Federico. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; ArgentinaFil: Luaces, Juan Pablo. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; ArgentinaFil: Otero-Losada, Matilde Estela. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; ArgentinaFil: Capani, Francisco. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires"; Argentina. Universidad Autónoma de Chile; Chile. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; Argentin
Topological phase transition in a RNA model in the de Gennes regime
We study a simplified model of the RNA molecule proposed by G. Vernizzi, H.
Orland and A. Zee in the regime of strong concentration of positive ions in
solution. The model considers a flexible chain of equal bases that can pairwise
interact with any other one along the chain, while preserving the property of
saturation of the interactions. In the regime considered, we observe the
emergence of a critical temperature T_c separating two phases that can be
characterized by the topology of the predominant configurations: in the large
temperature regime, the dominant configurations of the molecule have very large
genera (of the order of the size of the molecule), corresponding to a complex
topology, whereas in the opposite regime of low temperatures, the dominant
configurations are simple and have the topology of a sphere. We determine that
this topological phase transition is of first order and provide an analytic
expression for T_c. The regime studied for this model exhibits analogies with
that for the dense polymer systems studied by de GennesComment: 15 pages, 4 figure
Cholesterol modulates acetylcholine receptor diffusion by tuning confinement sojourns and nanocluster stability
Translational motion of neurotransmitter receptors is key for determining receptor number at the synapse and hence, synaptic efficacy. We combine live-cell STORM superresolution microscopy of nicotinic acetylcholine receptor (nAChR) with single-particle tracking, mean-squared displacement (MSD), turning angle, ergodicity, and clustering analyses to characterize the lateral motion of individual molecules and their collective behaviour. nAChR diffusion is highly heterogeneous: subdiffusive, Brownian and, less frequently, superdiffusive. At the single-track level, free walks are transiently interrupted by ms-long confinement sojourns occurring in nanodomains of ~36 nm radius. Cholesterol modulates the time and the area spent in confinement. Turning angle analysis reveals anticorrelated steps with time-lag dependence, in good agreement with the permeable fence model. At the ensemble level, nanocluster assembly occurs in second-long bursts separated by periods of cluster disassembly. Thus, millisecond-long confinement sojourns and second-long reversible nanoclustering with similar cholesterol sensitivities affect all trajectories; the proportion of the two regimes determines the resulting macroscopic motional mode and breadth of heterogeneity in the ensemble population.Fil: Mosqueira, Alejo. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Camino, Pablo A.. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Barrantes, Francisco Jose. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentin
Circadian and Metabolic Effects of Light: Implications in Weight Homeostasis and Health
Daily interactions between the hypothalamic circadian clock at the suprachiasmatic nucleus (SCN) and peripheral circadian oscillators regulate physiology and metabolism to set temporal variations in homeostatic regulation. Phase coherence of these circadian oscillators is achieved by the entrainment of the SCN to the environmental 24-h light:dark (LD) cycle, coupled through downstream neural, neuroendocrine, and autonomic outputs. The SCN coordinate activity and feeding rhythms, thus setting the timing of food intake, energy expenditure, thermogenesis, and active and basal metabolism. In this work, we will discuss evidences exploring the impact of different photic entrainment conditions on energy metabolism. The steady-state interaction between the LD cycle and the SCN is essential for health and wellbeing, as its chronic misalignment disrupts the circadian organization at different levels. For instance, in nocturnal rodents, non-24 h protocols (i.e., LD cycles of different durations, or chronic jet-lag simulations) might generate forced desynchronization of oscillators from the behavioral to the metabolic level. Even seemingly subtle photic manipulations, as the exposure to a "dim light" scotophase, might lead to similar alterations. The daily amount of light integrated by the clock (i.e., the photophase duration) strongly regulates energy metabolism in photoperiodic species. Removing LD cycles under either constant light or darkness, which are routine protocols in chronobiology, can also affect metabolism, and the same happens with disrupted LD cycles (like shiftwork of jetlag) and artificial light at night in humans. A profound knowledge of the photic and metabolic inputs to the clock, as well as its endocrine and autonomic outputs to peripheral oscillators driving energy metabolism, will help us to understand and alleviate circadian health alterations including cardiometabolic diseases, diabetes, and obesity.Fil: Plano, Santiago Andrés. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Casiraghi, Leandro Pablo. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa. Laboratorio de CronobiologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Garcia Moro, Paula. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa. Laboratorio de CronobiologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Paladino, Natalia. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa. Laboratorio de CronobiologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Golombek, Diego Andrés. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa. Laboratorio de CronobiologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Chiesa, Juan José. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa. Laboratorio de CronobiologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentin
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