25,185 research outputs found
Supersymmetry breaking as the origin of flavor
We present an effective flavor model for the radiative generation of fermion
masses and mixings based on a SU(5)xU(2) symmetry. We assume that the original
source of flavor breaking resides in the supersymmetry breaking sector. Flavor
violation is transmitted radiatively to the fermion Yukawa couplings at low
energy through finite supersymmetric threshold corrections. This model can fit
the fermion mass ratios and CKM matrix elements, explain the non-observation of
proton decay, and overcome present constraints on flavor changing processes
through an approximate radiative alignment between the Yukawa and the soft
trilinear sector. The model predicts new relations between dimensionless
fermion mass ratios in the three fermion sectors, and the quark mixing angles.Comment: 14 pages, RevTex
Non-dual modal operators as a basis for 4-valued accessibility relations in Hybrid logic
The modal operators usually associated with the notions of possibility and necessity are classically duals. This paper aims to defy that duality in a paraconsistent environment, namely in a Belnapian Hybrid logic where both propositional variables and accessibility relations are four-valued. Hybrid logic, which is an extension of Modal logic, incorporates extra machinery such as nominals – for uniquely naming states – and a satisfaction operator – so that the formula under its scope is evaluated in the state whose name the satisfaction operator indicates.
In classical Hybrid logic the semantics of negation, when it appears before compound formulas, is carried towards subformulas, meaning that eventual inconsistencies can be found at the level of nominals or propositional variables but appear unrelated to the accessibility relations. In this paper we allow inconsistencies in propositional variables and, by breaking the duality between modal operators, inconsistencies at the level of accessibility relations arise. We introduce a sound and complete tableau system and a decision procedure to check if a formula is a consequence of a set of formulas. Tableaux will be used to extract syntactic models for databases, which will then be compared using different inconsistency measures. We conclude with a discussion about bisimulation
Structure and equation of state of interaction site models for disc-shaped lamellar colloids
We apply RISM (Reference Interaction Site Model) and PRISM (polymer-RISM)
theories to calculate the site-site pair structure and the osmotic equation of
state of suspensions of circular or hexagonal platelets (lamellar colloids)
over a range of ratios of the particle diameter over thickness. Despite the
neglect of edge effects, the simpler PRISM theory yields results in good
agreement with the more elaborate RISM calculations, provided the correct form
factor, characterizing the intramolecular structure of the platelets, is used.
The RISM equation of state is sensitive to the number of sites used to model
the platelets, but saturates when the hard spheres, associated with the
interaction sites, nearly touch; the limiting equation of state agrees
reasonably well with available simulation data for all densities up to the
isotropic-nematic transition. When properly scaled with the second virial
coefficient, the equations of state of platelets with different aspect ratios
nearly collapse on a single master curve.Comment: 10 Pages, 11 Figures, Typesetted using RevTeX
A machine learning based framework to identify and classify long terminal repeat retrotransposons
Transposable elements (TEs) are repetitive nucleotide sequences that make up a large portion of eukaryotic genomes. They can move and duplicate within a genome, increasing genome size and contributing to genetic diversity within and across species. Accurate identification and classification of TEs present in a genome is an important step towards understanding their effects on genes and their role in genome evolution. We introduce TE-LEARNER, a framework based on machine learning that automatically identifies TEs in a given genome and assigns a classification to them. We present an implementation of our framework towards LTR retrotransposons, a particular type of TEs characterized by having long terminal repeats (LTRs) at their boundaries. We evaluate the predictive performance of our framework on the well-annotated genomes of Drosophila melanogaster and Arabidopsis thaliana and we compare our results for three LTR retrotransposon superfamilies with the results of three widely used methods for TE identification or classification: REPEATMASKER, CENSOR and LTRDIGEST. In contrast to these methods, TE-LEARNER is the first to incorporate machine learning techniques, outperforming these methods in terms of predictive performance , while able to learn models and make predictions efficiently. Moreover, we show that our method was able to identify TEs that none of the above method could find, and we investigated TE-LEARNER'S predictions which did not correspond to an official annotation. It turns out that many of these predictions are in fact strongly homologous to a known TE
The Link between the Compliance with Environmental Legislation on Separate Collection and the Municipal Solid Waste Costs
Promoting Agenda 2030 through Circular Economy transition requires improving waste system management and increasing separate collection. In Italy, municipal solid waste management is entrusted to the municipalities, most of which have not yet reached the minimum threshold of 65% for the separate collection imposed by the Environmental Code in 2012. This research aims to investigate the effect of compliance with environmental legislation by Italian municipalities on the total cost of municipal solid waste management, filling a shortage of literature studies on this issue. It also investigates the other significant factors affecting municipal solid waste costs, analysing a large dataset of 1914 municipalities. The study uses regression analysis on aggregate and regional samples and population-based subsamples to verify the existence of economies of scale or density. The results show that environmental compliance determines cost reduction in the northern regions, thanks to more efficient separate collection management and recycling activities in the downstream phases of the process. Instead, environmental compliance produces a cost increase in central regions due to the lack of waste recycling and composting infrastructure. Finally, in the conclusions, policy implications are drawn for the Italian case
Topical and Systemic Cannabidiol Improves Trinitrobenzene Sulfonic Acid Colitis in Mice
Background/Aims: Compounds of Cannabis sativa are known to exert anti-inflammatory properties, some of them without inducing psychotropic side effects. Cannabidiol (CBD) is such a side effect-free phytocannabinoid that improves chemically induced colitis in rodents when given intraperitoneally. Here, we tested the possibility whether rectal and oral application of CBD would also ameliorate colonic inflammation, as these routes of application may represent a more appropriate way for delivering drugs in human colitis. Methods: Colitis was induced in CD1 mice by trinitrobenzene sulfonic acid. Individual groups were either treated with CBD intraperitoneally (10 mg/kg), orally (20 mg/kg) or intrarectally (20 mg/kg). Colitis was evaluated by macroscopic scoring, histopathology and the myeloperoxidase (MPO) assay. Results: Intraperitoneal treatment of mice with CBD led to improvement of colonic inflammation. Intrarectal treatment with CBD also led to a significant improvement of disease parameters and to a decrease in MPO activity while oral treatment, using the same dose as per rectum, had no ameliorating effect on colitis. Conclusion: The data of this study indicate that in addition to intraperitoneal application, intrarectal delivery of cannabinoids may represent a useful therapeutic administration route for the treatment of colonic inflammation. Copyright (C) 2012 S. Karger AG, Base
Kinetic study of the oxide-assisted catalyst-free synthesis of silicon nitride nanowires
The synthesis of Si3N4 nanowires from the reaction of silicon nanoparticles
with N2 in the 1200-1440 C temperature range is reported. The nitridation
conditions are such that the reaction with nitrogen is favoured by the presence
of silicon oxide in the particles and by the active oxidation of silicon
without a catalyst. It is shown that the Si to Si3N4 conversion rate depends on
the amount of silicon particles used in the experiments and that, in general,
the reaction slows down for greater amounts. This trend is explained by
particle stacking, which restricts the exchange of gases between the furnace
atmosphere and the atmosphere around the inner particles. In a first stage,
local oxygen partial pressure increases around the inner particles and inhibits
nitridation locally. If the amount of reactant Si nanoparticles is small
enough, this extrinsic effect is avoided and the intrinsic nitridation kinetics
can be measured. Experiments show that intrinsic kinetics does not depend on
temperature
Morte súbita e angina vasoespástica
Variant angina is defined by chest pain occurring at rest associated with transitory ST segment elevation on ECG, and is caused by a spasm of a coronary artery. Frequently, variant angina is associated with atherosclerotic coronary obstruction and patients with normal coronary arteries are rare. Patients with variant angina and normal coronary arteries have good prognosis, and the development of ventricular arrhythmias or sudden death is rare. The authors present two cases of sudden cardiac death in patients with variant angina and normal coronary arteries
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