Optical detection of the ultrasound-induced pulsed thermal lens close to the ice-water phase transition.

Piezo-optic and thermo-optic coefficients are important material properties that play a critical role in the design and optimization of many optical devices. The ability to accurately measure and control these coefficients is essential for achieving high performance and reliability in a wide range of applications. In this article, we use the optical detection of the ultrasound-induced thermal lens effect to investigate these properties for water at low temperatures. The results show that the anomalous behavior of water around 4°C is easily observed. The thermal lens method is used to determine the temperature dependence of the piezo-optic and thermo-optic coefficients.

Integrated assessment of biomarker responses and microbiological analysis of oysters from São Luís Island, Brazil.

This study was conducted to evaluate the use of biochemical biomarkers and microbiological analysis to identify levels of oyster contamination at different ports in São Luís Island (Maranhão), Brazil. Oysters were analyzed for total coliforms, thermotolerant coliforms, Escherichia coli and Aeromonas spp. In addition, tissue was removed from the digestive gland to determine the glutathione-S-transferase (GST) and catalase (CAT) activity. The highest percentage of microbiological contamination of oyster samples occurred during the rainy season. The activity of GST and catalase in oysters was also higher in the rainy season, coinciding with the greatest abundance of total and thermotolerant coliforms. Among the prospective biomarkers, GST showed the best results for identification of areas with higher levels of contamination.

Analogies Between the Cracking Noise of Ethanol-Dampened Charcoal and Earthquakes.

We report on an extensive characterization of the cracking noise produced by charcoal samples when dampened with ethanol. We argue that the evaporation of ethanol causes transient and irregularly distributed internal stresses that promote the fragmentation of the samples and mimic some situations found in mining processes. The results show that, in general, the most fundamental seismic laws ruling earthquakes (the Gutenberg-Richter law, the unified scaling law for the recurrence times, Omori's law, the productivity law, and Båth's law) hold under the conditions of the experiment. Some discrepancies were also identified (a smaller exponent in the Gutenberg-Richter law, a stationary behavior in the aftershock rates for long times, and a double power-law relationship in the productivity law) and are related to the different loading conditions. Our results thus corroborate and elucidate the parallel between the seismic laws and fracture experiments caused by a more complex loading condition that also occurs in natural and induced seismicity (such as long-term fluid injection and gas-rock outbursts in mining processes).

Nonlinear Kramers equation associated with nonextensive statistical mechanics.

Stationary and time-dependent solutions of a nonlinear Kramers equation, as well as its associated nonlinear Fokker-Planck equations, are investigated within the context of Tsallis nonextensive statistical mechanics. Since no general analytical time-dependent solutions are found for such a nonlinear Kramers equation, an ansatz is considered and the corresponding asymptotic behavior is studied and compared with those known for the standard linear Kramers equation. The H-theorem is analyzed for this equation and its connection with Tsallis entropy is investigated. An application is discussed, namely the motion of Hydra cells in two-dimensional cellular aggregates, for which previous measurements have verified q-Gaussian distributions for velocity components and superdiffusion. The present analysis is in quantitative agreement with these experimental results.

Universal bursty behaviour in human violent conflicts.

Understanding the mechanisms and processes underlying the dynamics of collective violence is of considerable current interest. Recent studies indicated the presence of robust patterns characterizing the size and timing of violent events in human conflicts. Since the size and timing of violent events arises as the result of a dynamical process, we explore the possibility of unifying these observations. By analyzing available catalogs on violent events in Iraq (2003-2005), Afghanistan (2008-2010) and Northern Ireland (1969-2001), we show that the inter-event time distributions (calculated for a range of minimum sizes) obeys approximately a simple scaling law which holds for more than three orders of magnitude. This robust pattern suggests a hierarchical organization in size and time providing a unified picture of the dynamics of violent conflicts.

Miocardite crônica em um cão naturalmente infectado com Leishmania (Leishmania) infantum chagasi: aspectos clínicos e patológicos / Chronic myocarditis in a dog naturally infected by Leishmania (Leishmania) infantum chagasi: clinical and pathological aspects

A leishmaniose visceral (LV) é uma doença infecciosa crônica frequentemente fatal causada pela Leishmania infantum chagasi nas Américas. A enfermidade pode acometer vários órgãos, determinando diferentes manifestações clínicas. Contudo o envolvimento do coração raramente tem sido reportado em cães infectados por Leishmania sp. Dessa forma, descreve-se um caso de miocardite crônica com repercussões clínicas e patológicas em um cão naturalmente infectado por Leishmania infantum chagasi. A positividade para Leishmaniose Visceral foi determinada pela presença de anticorpos antiLeishmania sp. nos testes sorológicos (RIFI, ELISA e DPP) e confirmada por visualização de formas amastigotas de Leishmania sp. em punção aspirativa do linfonodo poplíteo. O exame cardiovascular revelou alterações radiográficas, eletrocardiográficas, na pressão arterial e nos biomarcardores cardíacos. Após eutanásia, amostras de tecido cardíaco foram avaliadas histologicamente e submetidas à imunomarcação, onde foi observado infiltrado mononuclear (plasmo-histiolinfocitário), com presença de estruturas arredondadas de coloracão marrom-amareladas (imunomarcadas), indicando formas amastigotas de Leishmania infantum chagasi no miocárdio. Os aspectos etiopatogênicos da leishmaniose visceral sobre o miocárdio neste caso podem estar relacionados tanto à presença do parasita quanto à resposta "reacional inespecífica" do tecido à agressão do parasita no organismo. Todavia ainda não se sabem se as cepas de Leishmania infantum chagasi da região semiárida paraibana apresentam algum tropismo por tecido cardíaco ou se induzem a reação imunológica cruzada, com implicações clínicas.

Visceral leishmaniasis (VL) is a chronic, often fatal infectious disease caused by Leishmania infantum chagasi in the Americas. The disease can affect many organs and may express different clinical forms. However, the involvement of the heart has rarely been reported in dogs infected by Leishmania sp. Thus, we describe a case of chronic myocarditis with clinical and pathological effects in a dog naturally infected by Leishmania infantum chagasi. Positivity for Visceral Leishmaniasis was determined by the presence of anti-Leishmania sp. in serological tests (IFAT, ELISA and DPP) and confirmed by visualization of amastigote forms of the parasite in the popliteal lymph node aspiration samples. The cardiovascular clinical examination showed changes in the radiographic, ECG, blood pressure and heart biomarkers. After euthanasia, heart tissue samples were histologically examined and underwent our immunohistochemistry assessment, where mononuclear infiltrate was observed (plasma cells, lymphocytes and macrophages) with the presence of rounded brownish-yellow (immunomarked) cells, indicating amastigotes of Leishmania infantum chagasi within the myocardium. The etiopathogenic aspects of visceral leishmaniasis in the myocardium in this case may be related either to the presence of the parasite or the "nonspecific reactive" response of the tissue attributable to the aggression of the parasite in the body. However, it is not known if the strains of Leishmania infantum chagasi found in the semi-arid of Paraíba have some tropism for cardiac tissue or if they induce immunological cross-reaction with clinical implications.

Engagement in the electoral processes: scaling laws and the role of political positions.

We report on a statistical analysis of the engagement in the electoral processes of all Brazilian cities by considering the number of party memberships and the number of candidates for mayor and councillor. By investigating the relationships between the number of party members and the population of voters, we have found that the functional forms of these relationships are well described by sublinear power laws (allometric scaling) surrounded by a multiplicative log-normal noise. We have observed that this pattern is quite similar to those we previously reported for the relationships between the number of candidates (mayor and councillor) and population of voters [Europhys. Lett. 96, 48001 (2011)], suggesting that similar universal laws may be ruling the engagement in the electoral processes. We also note that the power-law exponents display a clear hierarchy, where the more influential is the political position the smaller is the value of the exponent. We have also investigated the probability distributions of the number of candidates (mayor and councillor), party memberships, and voters. The results indicate that the most influential positions are characterized by distributions with very short tails, while less influential positions display an intermediate power-law decay before showing an exponential-like cutoff. We discuss the possibility that, in addition to the political power of the position, limitations in the number of available seats can also be connected with this changing of behavior. We further believe that our empirical findings point out to an under-representation effect, where the larger the city is, the larger are the obstacles for more individuals to become directly engaged in the electoral process.

Annihilation dynamics of stringlike topological defects in a nematic lyotropic liquid crystal.

Topological defects can appear whenever there is some type of ordering. Its ubiquity in nature has been the subject of several studies, from early Universe to condensed matter. In this work, we investigated the annihilation dynamics of defects and antidefects in a lyotropic nematic liquid crystal (ternary mixture of potassium laurate, decanol and deionized-destillated water) using the polarized optical light microscopy technique. We analyzed Schlieren textures with topological defects produced due to a symmetry breaking in the transition of the isotropic to nematic calamitic phase after a temperature quench. As result, we obtained for the distance D between two annihilating defects (defect-antidefect pair), as a function of time t remaining for the annihilation, the scaling law D âˆ t(α), with α = 0.390 and standard deviation σ = 0.085. Our findings go in the direction to extend experimental results related to dynamics of defects in liquid crystals since only thermotropic and polymerics ones had been investigated. In addition, our results are in good quantitative agreement with previous investigations on the subject.

Antipersistent behavior of defects in a lyotropic liquid crystal during annihilation.

We report on the dynamical behavior of defects of strength s=±1/2 in a lyotropic liquid crystal during the annihilation process. By following their positions using time-resolved polarizing microscopy technique, we present statistically significant evidence that the relative velocity between defect pairs is Gaussian distributed, antipersistent, and long-range correlated. We further show that simulations of the Lebwohl-Lasher model reproduce quite well our experimental findings.

Ehrlichia canis in dogs in a semiarid region of Northeastern Brazil: serology, molecular detection and associated factors.

This study investigated infection by Ehrlichia spp. agents by PCR, immunofluorescence assay test (IFAT), and by Giemsa-stained blood smears in 108 dogs from a semiarid region of the state of Paraíba, Northeastern Brazil. Seventy-five (69.4%) of the 108 dogs were found to be seropositive to Ehrlichia canis, while only four dogs (3.7%) were positive in real-time PCR for E. canis. In six dogs (5.6%) E. canis-like morulae were observed in monocytes. Animals that stayed in environment whose floor was dried dirt, and dogs whose owners reported low frequency of cleaning the dog environment had higher (P<0.05) PCR positivity for E. canis. Increasing seropositivity was found in older dogs (P=0.012). This study provides the first molecular detection of E. canis in the semiarid region of Northeastern Brazil.

Scale-invariant structure of size fluctuations in plants.

A wide range of physical and biological systems exhibit complex behaviours characterised by a scale-invariant structure of the fluctuations in their output signals. In the context of plant populations, scaling relationships are typically allometric. In this study, we analysed spatial variation in the size of maize plants (Zea Mays L.) grown in agricultural plots at constant densities and found evidence of scaling in the size fluctuations of plants. The findings indicate that the scaling of the probability distribution of spatial size fluctuation exhibits non-Gaussian behaviour compatible with a Lévy stable process. The scaling relationships were observed for spatial scales spanning three orders of magnitude. These findings should provide additional information for the selection and development of empirically accurate models of pattern formation in plant populations.

Different diffusive regimes, generalized Langevin and diffusion equations.

We investigate a generalized Langevin equation (GLE) in the presence of an additive noise characterized by the mixture of the usual white noise and an arbitrary one. This scenario lead us to a wide class of diffusive processes, in particular the ones whose noise correlation functions are governed by power laws, exponentials, and Mittag-Leffler functions. The results show the presence of different diffusive regimes related to the spreading of the system. In addition, we obtain a fractional diffusionlike equation from the GLE, confirming the results for long time.

Identifying and modeling patterns of tetrapod vertebrate mortality rates in the Gulf of Mexico oil spill.

The accidental oil spill in the Gulf of Mexico in 2010 has caused perceptible damage to marine and freshwater ecosystems. The large quantity of oil leaking at a constant rate and the long duration of the event caused an exponentially increasing mortality of vertebrates. Using data provided by NOAA and USFWS, we assessed the effects of this event on birds, sea turtles, and mammals. Mortality rates (measured as the number of carcasses recorded per day) were exponential for all three groups. Birds were the most affected group, as indicated by the steepest increase of mortality rates over time. For sea turtles and mammals, an exponential increase in mortality was observed after an initial delay. These exponential behaviors are consistent with a unified scenario for the mortality rate for tetrapod vertebrates. However, at least for mammals, pre-spill data seem to indicate that the growth in the mortality rate is not entirely a consequence of the spill.

Anestesia epidural com associação medetomidina e lidocaína, em gatos pré-medicados com acepromazina e midazolam / Epidural anesthesia with lidocaine and association medetomidine in cats pre-medicated with acepromazine and midazolam

Avaliaram-se os efeitos anestésicos promovidos pela associação medetomidina e lidocaína por via epidural, em gatos pré-tratados com acepromazina e midazolam. Foram utilizados 10 gatos adultos, machos e fêmeas, hígidos e com média de peso de 2,5±0,6kg, distribuídos em dois grupos (GM e GL) de igual número (n=5). Administraram-se, como medicação pré-anestésica, acepromazina, 0,2mg/kg, e midazolam, 0,5mg/kg, via intramuscular, e 20 minutos depois, nos animais do GM, por via epidural, lidocaína, 4,4mg/kg, associada à medetomidina, 0,02mg/kg. Os gatos do GL receberam lidocaína, 4,4mg/kg, associada à solução de NaCl a 0,9 por cento. As avaliações ocorreram antes da pré-anestesia (MPA), 20 minutos após a MPA e antes da anestesia epidural, e aos 10, 20, 30 e 40 minutos após a anestesia epidural, respectivamente, T-20, T0, T10, T20, T30 e T40. Foram avaliados: frequência cardíaca (FC) e respiratória (FR), temperatura do corpo, saturação de oxiemoglobina, analgesia, miorrelaxamento e período de recuperação. No GM, a FC diminuiu em T20, T30 e T40 em relação ao T-20 e T10 e foi mais baixa que a FC do GL em T20, T30 e T40, respectivamente, 86, 91 e 88 bat/min e 194, 205 e 177 bat/min. A FR variou entre o T-20 e os outros momentos de avaliação nos animais do GL. Nas variáveis eletrocardiográficas, houve diferenças entre T20, T30 e T40 e T-20 e T0, valores de 235, 238 e 240ms e 156 e 161ms, respectivamente, somente no GM. Este grupo diferiu do GL nas avaliações em T20, T30 e T40, valores de 147, 132 e 150ms para os gatos do GL. Oitenta por cento dos gatos tiveram analgesia intensa, e em todos os animais ocorreu relaxamento da mandíbula e da língua. O tempo de recuperação foi de 40 e 15min no GM e no GL, respectivamente. Concluiu-se que a associação lidocaína com medetomidina promoveu plano anestésico estável com grau de anestesia e recuperação anestésica de boa qualidade.

The anesthetic effects due to the association of medetomidine and epidural lidocaine in cats pretreated with acepromazine and midazolam were evaluated. Ten adult cats were used, male and female, healthy and weighing 2.5±0.6kg. They were divided into two groups (GM and GL) of equal numbers (n=5). Premedication with acepromazine, 0.2mg/kg, and midazolam, 0.5mg/kg, intramuscular was administered. Twenty minutes later, GM animals were given epidural lidocaine, 4.4mg/kg, associated with medetomidine, 0.02mg/kg. GL cats received lidocaine, 4.4mg/kg, associated with NaCl 0.9 percent. Assessments occurred before the pre-anesthesia (MPA), 20 minutes after premedication and before the epidural block, and 10, 20, 30 and 40 minutes after epidural anesthesia, respectively, T-20, T0, T10, T20, T30 and T40. Heart rate, respiratory rate, body temperature, oxyhemoglobin saturation, analgesia, muscle relaxation and recovery period were evaluated. In GM cats the heart rate decreased at T20, T30 and T40 as compared to T-20 and T10 and was lower than the heart rate in the GL cats at T20, T30 and T40, values being, respectively, 86, 91 and 88 beats/min and 194, 205 and 177 beats/min. The respiratory rate ranged from T-20 and the other time points in GL animals. Concerning electrocardiographic variables, in GM cats significant differences between T20, T30 and T40 and T0 and T-20, were observed, values being 235, 238 and 156 and 161ms and 240ms, respectively. GM animals differed from GL in T20, T30 and T40, values being 147, 132 and 150ms for GL cats. Eighty percent of the cats had severe pain and in all animals there was a relaxation of the jaw and tongue. The recovery time was 40 and 15 min at GM and GL, respectively. It was concluded that the association promoted lidocaine with medetomidine anesthesia with a stable level of anesthesia and anesthetic recovery of good quality.

Universal patterns in sound amplitudes of songs and music genres.

We report a statistical analysis of more than eight thousand songs. Specifically, we investigated the probability distribution of the normalized sound amplitudes. Our findings suggest a universal form of distribution that agrees well with a one-parameter stretched Gaussian. We also argue that this parameter can give information on music complexity, and consequently it helps classify songs as well as music genres. Additionally, we present statistical evidence that correlation aspects of the songs are directly related to the non-Gaussian nature of their sound amplitude distributions.

Spatial and temporal variability of canopy cover and understory light in a Cerrado of Southern Brazil.

Canopy cover has significant effects on the understory environment, including upon light availability for seedling growth. The aim of the present study was to verify spatial heterogeneity and seasonal changes in the canopy cover of a dense Cerrado area, and their relationship to understory photosynthetic active radiation availability. Leaf area index (LAI) values in the rainy season varied from 0.9 to 4.83, with 40% of the values ranging from 4.0 to 5.0, while in the dry season LAI varied from 0.74 to 3.3, with 53% of the values oscillating from 2.0 to 3.0. Understory light (Q(i)) and the Lambert-Beer ratio (Q(i)/Q(o)) were taken around noon on sunny days (between 11:00 AM and 1:00 PM). They were also statistically different (p < 0.01) between the dry and wet seasons, with 72% of sampled points in the rainy season presenting photosynthetic photon flux density (PPFD) values lower than 250 micromol x m(-2)/s around noon, whereas in the dry season, most PPFD values varied from 1500 to 1817 micromol x m(-2)/s, thus providing high light availability for understory plants. In most of the studied sites, understory plants did not even receive enough light for 50% of their photosynthetic capacity in the wet season. In contrast during the dry season, Q(i)/Q(o) values of 0.8 to 1.0 were observed in more than 50% of the points, thereby allowing for photosynthetic light saturation. Thus, light variability around noon was higher during the dry season than in the wet season, its heterogeneity being related to spatial complexity in the canopy cover.

Universal features in the growth dynamics of religious activities.

We quantify and analyze the growth dynamics of a religious group in 140 countries for a 47-year period (1959-2005). We find that (i) the distribution of annual logarithmic growth rates exhibits the same functional form for distinct size scales and (ii) the standard deviation of growth rates scales with size as a power law. Both findings hold for distinct measures of religious activity. These results are in surprising agreement with those found in the study of economic activities and scientific research, suggesting that religious activities are governed by universal growth mechanisms. We also compare the empirical findings on religious activities with the predictions of general models recently proposed in the context of complex organizations. Our findings should provide useful information for a better understanding of the mechanisms governing the growth of religion.

General solution of the diffusion equation with a nonlocal diffusive term and a linear force term.

We obtain a formal solution for a large class of diffusion equations with a spatial kernel dependence in the diffusive term. The presence of this kernel represents a nonlocal dependence of the diffusive process and, by a suitable choice, it has the spatial fractional diffusion equations as a particular case. We also consider the presence of a linear external force and source terms. In addition, we show that a rich class of anomalous diffusion, e.g., the Lévy superdiffusion, can be obtained by an appropriated choice of kernel.

A non-Gaussian model in polymeric network.

We investigate a finite chain approximation, the non-Gaussian Tsallis distribution, to the polymeric network, which gives an improvement to the Gaussian model. This distribution presents some necessary characteristics, like a cutoff to the maximum chain length and a continuous limit to the Gaussian one for a large number of monomers. It also presents a simple quadratic structure that allows to generalize the Gaussian properties such as exact-moments calculation and Wick theorem. We obtain the free-energy density in its full tensorial structure.

Long-time behavior of spreading solutions of Schrödinger and diffusion equations.

We investigate the asymptotic time behavior of the solutions of a large class of linear differential equations that generalize the free-particle Schrödinger and diffusion equations, containing the standard ones as particular cases. We find general scalings that depend only on characteristic features of both the arbitrary initial condition and the Green function associated with the evolution equation. Basically, the amplitude of a long-time solution can be expressed in terms of low order moments of the initial condition (if finite) and low order spatial derivatives of the Green function. These derivatives can also be of the fractional type, which naturally arise when moments are divergent. We apply our results to a large class of differential equations that includes the fractional Schrödinger and Lévy diffusion equations. In particular, we show that, except for threshold cases, the amplitude of a packet may follow the asymptotic law t-alpha, with arbitrary positive alpha.