Distributed Maintenance of Anytime Available Spanning Trees in Dynamic Networks

We address the problem of building and maintaining distributed spanning trees in highly dynamic networks, in which topological events can occur at any time and any rate, and no stable periods can be assumed. In these harsh environments, we strive to preserve some properties such as cycle-freeness or the existence of a root in each tree, in order to make it possible to keep using the trees uninterruptedly (to a possible extent). Our algorithm operates at a coarse-grain level, using atomic pairwise interactions in a way akin to recent population protocol models. The algorithm relies on a perpetual alternation of \emph{topology-induced splittings} and \emph{computation-induced mergings} of a forest of spanning trees. Each tree in the forest hosts exactly one token (also called root) that performs a random walk {\em inside} the tree, switching parent-child relationships as it crosses edges. When two tokens are located on both sides of a same edge, their trees are merged upon this edge and one token disappears. Whenever an edge that belongs to a tree disappears, its child endpoint regenerates a new token instantly. The main features of this approach is that both \emph{merging} and \emph{splitting} are purely localized phenomenons. In this paper, we present and motivate the algorithm, and we prove its correctness in arbitrary dynamic networks. Then we discuss several implementation choices around this general principle. Preliminary results regarding its analysis are also discussed, in particular an analytical expression of the expected merging time for two given trees in a static context.Comment: Distributed Maintenance of Anytime Available Spanning Trees in Dynamic Networks, Poland (2013

Local dimension and finite time prediction in spatiotemporal chaotic systems

We show how a recently introduced statistics [Patil et al, Phys. Rev. Lett. 81 5878 (2001)] provides a direct relationship between dimension and predictability in spatiotemporal chaotic systems. Regions of low dimension are identified as having high predictability and vice-versa. This conclusion is reached by using methods from dynamical systems theory and Bayesian modelling. We emphasize in this work the consequences for short time forecasting and examine the relevance for factor analysis. Although we concentrate on coupled map lattices and coupled nonlinear oscillators for convenience, any other spatially distributed system could be used instead, such as turbulent fluid flows.Comment: 5 pagers, 7 EPS figure

Semileptonic D decay into scalar mesons: a QCD sum rule approach

Semileptonic decays of D-mesons into scalar hadronic states are investigated. Two extreme cases are considered: a) the meson decays directly into an uncorrelated scalar state of two two mesons and b) the decay proceeds via resonance formation. QCD sum rules including instanton contributions are used to calculate total and differential decay rates under the two assumptions.Comment: 18 pages, 9 figures, e-mail: [email protected]

Spatial distribution of bed variables, animal welfare indicators, and milk production in a closed compost-bedded pack barn with a negative tunnel ventilation system

This research aimed to characterize, evaluate and compare the spatial distribution of the leading bed variables, animal welfare indicators, and milk production in a closed compost-bedded pack barn (CBP) with a negative tunnel ventilation system, for summer and winter periods. The study was carried out in a CBP located in the Zona da Mata region, Minas Gerais, Brazil. The geostatistical modeling technique evaluated the variables of temper ature, moisture content, and pH (on the surface and depth of 0.20m) across the length of the bed. Bed samples were characterized for carbon (C), nitrogen (N), and C:N ratio. Cows housed in the CBP were assessed for locomotion and hygiene scores and average milk production. To evaluate the thermoregulation of the cows, the respiratory rate (RR) and surface temperature (ST) were measured. Geostatistical analysis showed spatial dependence and the non-uniformity of the spatial distribution of bed variables. The worst levels of bed tem perature and moisture were found in the regions close to the evaporative cooling plate, surrounding the feeding alley, and in the region with the highest cow stocking. The C:N ratio, obtained in both climatic seasons of the year, remained outside the recommended range for ideal composting. During the summer and winter, the bed variables’ values suggest that the material was below levels for optimal composting; however, the aerated inner layer was biologically active. The high animal density significantly impacted the worsening of the bed moisture content and internal temperature. In general, dairy cows showed adequate hygiene (score of 1 and 2) and locomotion (score of 0 and 1) scores for the two climatic seasons evaluated, indicating good welfare conditions. In relation to RR and ST, the summer period presented less favorable environmental conditions. During winter, the average milk production was 28.1 ± 7.2 kg day-1, and during summer, it was 26.9 ± 6.7 kg day-1

Affine Toda model coupled to matter and the string tension in QCD2_{2}

The $sl(2)$ affine Toda model coupled to matter (ATM) is shown to describe various features, such as the spectrum and string tension, of the low-energy effective Lagrangian of QCD$_{2}$ (one flavor and $N$ colors). The corresponding string tension is computed when the dynamical quarks are in the {\sl fundamental} representation of SU(N) and in the {\sl adjoint} representation of SU(2).Comment: LaTex, 10 pages. Revised version to appear in Phys. Rev.

Ocean acidification may slow the pace of tropicalization of temperate fish communities

Poleward range extensions by warm-adapted sea urchins are switching temperate marine ecosystems from kelp-dominated to barren-dominated systems that favour the establishment of range-extending tropical fishes. Yet, such tropicalization may be buffered by ocean acidification, which reduces urchin grazing performance and the urchin barrens that tropical range-extending fishes prefer. Using ecosystems experiencing natural warming and acidification, we show that ocean acidification could buffer warming-facilitated tropicalization by reducing urchin populations (by 87%) and inhibiting the formation of barrens. This buffering effect of CO₂ enrichment was observed at natural CO₂ vents that are associated with a shift from a barren-dominated to a turf-dominated state, which we found is less favourable to tropical fishes. Together, these observations suggest that ocean acidification may buffer the tropicalization effect of ocean warming against urchin barren formation via multiple processes (fewer urchins and barrens) and consequently slow the increasing rate of tropicalization of temperate fish communities.Ericka O.C. Coni, Ivan Nagelkerken, Camilo M. Ferreira, Sean D. Connell and David J. Boot

COMPORTAMENTO DA INGESTÃO EM BOVINOS (RUMINANTES) EM PASTAGEM DE CAPIM Brachiaria decumbens NA REGIÃO CENTRO-OESTE DO BRASIL

An experiment has been carried out aiming to evaluate the ingestion behavior of young heifers, heifers and cows in pastures of Brachiaria decumbens, in the system of continuous stocking with three categories representing the treatments, each one with ten repetitions. The experimental period  was of 30 days, being 20 for adaptation of the experimental animals and 10 for three evaluations with duration of 24 hours each, in intervals of five days. The results of the Tukey test demonstrated that the cows grazed during more time (12 hours) than the young heifers (0.5 hours) and the heifers (10.25 hours). Statistic differences were not observed among the animals for the rumination time (7.25, 7.39 and 7.40, respectivety). The cows displayed larger bite rate (41.30) than the heifers and the young heifers. This result suggest that there was a compensatory mechanism between the times of grazing and the bite rates, so that the animals with more nutritional requirement regulated the amount of ingested forage, incrementing the grazing time.Foi conduzido um experimento com o objetivo de avaliar o comportamento na ingestão de bezerras, novilhas e vacas leiteiras em pastagens de Brachiaria decumbens, no sistema de lotação contínua com taxa de lotação variável. O delineamento experimental foi inteiramente casualizado, com três categorias animais representando os tratamentos, cada um com dez repetições. O período experimental foi de 30 dias, sendo 20 para adaptação dos animais e 10 para avaliações, que consistiram de três, com duração de 24 horas cada, em intervalos de cinco dias. O teste de Tukey demonstrou que as vacas pastejaram mais tempo (12 horas) que as novilhas (10,50 horas) e as bezerras (10,25 horas). Não foi observada diferença estatística entre os animais para o tempo de ruminação (7,25, 7,39 e 7,40, horas respectivamente). A taxa de bocados diurnos foi maior para as vacas do que para os novilhos e bezerros. Os resultados sugerem que houve um mecanismo de compensação entre os tempos de pastejo e as taxas de bocado, de modo que os animais mais exigentes pudessem regular a quantidade de forragem ingerida aumentando o tempo de pastejo

Transfer printed multi-color integrated devices for visible light communication applications

Integrated multi-color devices for visible light communication applications are fabricated by transfer printing blue-emitting GaN light emitting diodes (LEDs) onto a green-emitting LED array and a colloidal quantum dot color-converter structure

Study of Heparin in Intestinal Ischemia and Reperfusion in Rats: Morphologic and Functional Evaluation

AbstractTo study whether treatment with heparin (HEP) attenuates intestinal dysfunction caused by ischemia (I) and reperfusion (R), rats were treated with HEP (100 U/kg intravenously) or saline solution (SS) before I (60 min), which was produced by occlusion of the superior mesenteric artery, and R (120 min). After I or I/R, we mounted 2-cm jejunal segment in an organ bath to study neurogenic contractions stimulated by electrical pulses or KCl, using a digital recording system. Thin jejunal slices were stained with hematoxylin and eosin for optical microscopy. Compared with the sham group, jejunal contractions were similar in the I + HEP and the I/R + HEP groups, but reduced in the I + SS and the I/R + SS groups. The jejunal enteric nerves were damaged in the I + SS and the I/R + SS, but not in the I + HEP and the I/R + HEP cohorts. These results suggested that HEP attenuated intestinal dysfunction caused by I and I/R

Naturalness and theoretical constraints on the Higgs boson mass

Arbitrary regularization dependent parameters in Quantum Field Theory are usually fixed on symmetry or phenomenology grounds. We verify that the quadratically divergent behavior responsible for the lack of naturalness in the Standard Model (SM) is intrinsically arbitrary and regularization dependent. While quadratic divergences are welcome for instance in effective models of low energy QCD, they pose a problem in the SM treated as an effective theory in the Higgs sector. Being the very existence of quadratic divergences a matter of debate, a plausible scenario is to search for a symmetry requirement that could fix the arbitrary coefficient of the leading quadratic behavior to the Higgs boson mass to zero. We show that this is possible employing consistency of scale symmetry breaking by quantum corrections. Besides eliminating a fine-tuning problem and restoring validity of perturbation theory, this requirement allows to construct bounds for the Higgs boson mass in terms of $\delta m^2/m^2_H$ (where $m_H$ is the renormalized Higgs mass and $\delta m^2$ is the 1-loop Higgs mass correction). Whereas $\delta m^2/m^2_H<1$ (perturbative regime) in this scenario allows the Higgs boson mass around the current accepted value, the inclusion of the quadratic divergence demands $\delta m^2/m^2_H$ arbitrarily large to reach that experimental value.Comment: 6 pages, 4 figure