4,575 research outputs found
Quark matter revisited with non extensive MIT bag model
In this work we revisit the MIT bag model to describe quark matter within
both the usual Fermi-Dirac and the Tsallis statistics. We verify the effects of
the non-additivity of the latter by analysing two different pictures: the first
order phase transition of the QCD phase diagram and stellar matter properties.
While, the QCD phase diagram is visually affected by the Tsallis statistics,
the resulting effects on quark star macroscopic properties are barely noticed.Comment: 10 pagens, 5 figure
Compactlike kinks and vortices in generalized models
This work deals with the presence of topological defects in k-field models,
where the dynamics is generalized to include higher order power in the kinetic
term. We investigate kinks in (1,1) dimensions and vortices in (2,1)
dimensions, focusing on some specific features of the solutions. In particular,
we show how the kinks and vortices change to compactlike solutions, controlled
by the parameter used to introduce the generalized models.Comment: 7 pages, 7 figures. Version to be published in PR
First-order transition in small-world networks
The small-world transition is a first-order transition at zero density of
shortcuts, whereby the normalized shortest-path distance undergoes a
discontinuity in the thermodynamic limit. On finite systems the apparent
transition is shifted by . Equivalently a ``persistence
size'' can be defined in connection with finite-size
effects. Assuming , simple rescaling arguments imply that
. We confirm this result by extensive numerical simulation in one to
four dimensions, and argue that implies that this transition is
first-order.Comment: 4 pages, 3 figures, To appear in Europhysics Letter
More Discriminants with the Brezing-Weng Method
The Brezing-Weng method is a general framework to generate families of
pairing-friendly elliptic curves. Here, we introduce an improvement which can
be used to generate more curves with larger discriminants. Apart from the
number of curves this yields, it provides an easy way to avoid endomorphism
rings with small class number
Melhoramento genético e produção de rainhas de Apis mellifera.
bitstream/item/87876/1/MELHORAMENTO-GENETICO.pd
Downside risk in reservoir management
Downside risk, which refers to deviations below a threshold, is often important in
water management decisions, especially in areas with large and skewed variations in
precipitation patterns. In this paper, we present a model for a reservoir manager who
is downside risk averse and who performs a dynamic allocation of irrigation water,
taking into account the negative effects of droughts on farm profits and different
environmental constraints. We analyse the water stock, flows and agricultural profits
for alternative environmental restrictions and thresholds for irrigation levels and find
that stricter environmental constraints increase total water supply and carryover
stock, while higher penalty thresholds lead to their overall decrease. Furthermore,
increasing penalty thresholds leads to a higher emphasis on avoiding shortages, at the
expense of lower average profits.info:eu-repo/semantics/acceptedVersio
Relativistic Mean Field Approximation in a Density Dependent Parametrization Model at Finite Temperature
In this work we calculate the equation of state of nuclear matter for
different proton fractions at zero and finite temperature within the Thomas
Fermi approach considering three different parameter sets: the well-known NL3
and TM1 and a density dependent parametrization proposed by Typel and Wolter.
The main differences are outlined and the consequences of imposing
beta-stability in these models are discussed.Comment: 13 pages, 10 figure
Detrended Fluctuation Analysis of Systolic Blood Pressure Control Loop
We use detrended fluctuation analysis (DFA) to study the dynamics of blood
pressure oscillations and its feedback control in rats by analyzing systolic
pressure time series before and after a surgical procedure that interrupts its
control loop. We found, for each situation, a crossover between two scaling
regions characterized by exponents that reflect the nature of the feedback
control and its range of operation. In addition, we found evidences of
adaptation in the dynamics of blood pressure regulation a few days after
surgical disruption of its main feedback circuit. Based on the paradigm of
antagonistic, bipartite (vagal and sympathetic) action of the central nerve
system, we propose a simple model for pressure homeostasis as the balance
between two nonlinear opposing forces, successfully reproducing the crossover
observed in the DFA of actual pressure signals
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