11,188 research outputs found
Scaling limit for a drainage network model
We consider the two dimensional version of a drainage network model
introduced by Gangopadhyay, Roy and Sarkar, and show that the appropriately
rescaled family of its paths converges in distribution to the Brownian web. We
do so by verifying the convergence criteria proposed by Fontes, Isopi, Newman
and Ravishankar.Comment: 15 page
Properties of Solutions in 2+1 Dimensions
We solve the Einstein equations for the 2+1 dimensions with and without
scalar fields. We calculate the entropy, Hawking temperature and the emission
probabilities for these cases. We also compute the Newman-Penrose coefficients
for different solutions and compare them.Comment: 16 pages, 1 figures, PlainTeX, Dedicated to Prof. Yavuz Nutku on his
60th birthday. References adde
On the Nonlinear Stability of Asymptotically Anti-de Sitter Solutions
Despite the recent evidence that anti-de Sitter spacetime is nonlinearly
unstable, we argue that many asymptotically anti-de Sitter solutions are
nonlinearly stable. This includes geons, boson stars, and black holes. As part
of our argument, we calculate the frequencies of long-lived gravitational
quasinormal modes of AdS black holes in various dimensions. We also discuss a
new class of asymptotically anti-de Sitter solutions describing noncoalescing
black hole binaries.Comment: 26 pages. 5 figure
On the benefits of speech and touch interaction with communication services for mobility impaired users
Although technology for communication has evolved tremendously over the past decades, mobility impaired individuals still face many difficulties interacting with communication services, either due to HCI issues or intrinsic design problems with the services. In this paper we present the results of a usability study, conducted with a group of five mobility impaired users, comprising paraplegic and quadriplegic individuals. The study participants carried out a set of tasks with a multimodal (speech, touch, gesture, keyboard and mouse) and multiplatform (mobile, desktop) prototype, offering an integrated access to communication and entertainment services, such as email, agenda, conferencing and social media. The prototype was designed to take into account the requirements captured from these users, with the objective of evaluating if the use of multimodal interfaces for communication and social media services, could improve the interaction with such services. Our study revealed that a multimodal prototype system, offering natural interaction modalities, especially supporting speech and touch, can in fact improve access to the presented services, contributing to a better social inclusion of mobility impaired individuals.info:eu-repo/semantics/acceptedVersio
Systematic Implementation of Implicit Regularization for Multi-Loop Feynman Diagrams
Implicit Regularization (IReg) is a candidate to become an invariant
framework in momentum space to perform Feynman diagram calculations to
arbitrary loop order. In this work we present a systematic implementation of
our method that automatically displays the terms to be subtracted by
Bogoliubov's recursion formula. Therefore, we achieve a twofold objective: we
show that the IReg program respects unitarity, locality and Lorentz invariance
and we show that our method is consistent since we are able to display the
divergent content of a multi-loop amplitude in a well defined set of basic
divergent integrals in one loop momentum only which is the essence of IReg.
Moreover, we conjecture that momentum routing invariance in the loops, which
has been shown to be connected with gauge symmetry, is a fundamental symmetry
of any Feynman diagram in a renormalizable quantum field theory
Ultraspinning instability of rotating black holes
Rapidly rotating Myers-Perry black holes in d>5 dimensions were conjectured
to be unstable by Emparan and Myers. In a previous publication, we found
numerically the onset of the axisymmetric ultraspinning instability in the
singly-spinning Myers-Perry black hole in d=7,8,9. This threshold signals also
a bifurcation to new branches of axisymmetric solutions with pinched horizons
that are conjectured to connect to the black ring, black Saturn and other
families in the phase diagram of stationary solutions. We firmly establish that
this instability is also present in d=6 and in d=10,11. The boundary conditions
of the perturbations are discussed in detail for the first time and we prove
that they preserve the angular velocity and temperature of the original
Myers-Perry black hole. This property is fundamental to establish a
thermodynamic necessary condition for the existence of this instability in
general rotating backgrounds. We also prove a previous claim that the
ultraspinning modes cannot be pure gauge modes. Finally we find new
ultraspinning Gregory-Laflamme instabilities of rotating black strings and
branes that appear exactly at the critical rotation predicted by the
aforementioned thermodynamic criterium. The latter is a refinement of the
Gubser-Mitra conjecture.Comment: 38 pages, 6 figures, 1 tabl
Weight-length relationship, condition factor and blood parameters of farmed Cichla temensis Humboldt, 1821 (Cichlidae) in central Amazon.
Farming of native carnivore fish species has drawn attention due to their promising use in aquaculture. Among these species, tucunaré of the genus Cichla stand out, them being of high economical interest for sport fishing and Amazon's industry of ornamental fish. The present study describes the weight-length relationship (WLR), relative condition factor (Kn), red blood cell parameters, thrombocytes and leukocytes count of Cichla temensis Humboldt, 1821, farmed in central Amazon. Fish that underwent food training during fingerling culture received extruded ration containing 45% of crude protein during fattening, and had Kn with values from 0.925-1.199, which indicated good health condition during the culture. The equation obtained from the WLR was W = 0.0073Lt3.1435, indicating an isometric growth, which is the desirable for fish of fish farm. Red blood cell counts, total thrombocyte and leukocyte counts, hematocrit, hemoglobin concentration, mean corpuscular volume (MCV), concentration of mean corpuscular hemoglobin (MCHC), lymphocytes, monocytes and neutrophils had intra-specific variation. A significant (p<0.001) positive correlation of the red blood cells number with the hemoglobin concentration and hematocrit was found. These are the first sets of blood parameters for C. temensis and could be used as reference for comparison in further studies to evaluate the health status of this fish in different environments, because assessment of these parameters may be used as quick tool for diagnosing diseases, stress and malnutrition
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