Sliding blocks with random friction and absorbing random walks

With the purpose of explaining recent experimental findings, we study the distribution $A(\lambda)$ of distances $\lambda$ traversed by a block that slides on an inclined plane and stops due to friction. A simple model in which the friction coefficient $\mu$ is a random function of position is considered. The problem of finding $A(\lambda)$ is equivalent to a First-Passage-Time problem for a one-dimensional random walk with nonzero drift, whose exact solution is well-known. From the exact solution of this problem we conclude that: a) for inclination angles $\theta$ less than \theta_c=\tan(\av{\mu}) the average traversed distance \av{\lambda} is finite, and diverges when $\theta \to \theta_c^{-}$ as \av{\lambda} \sim (\theta_c-\theta)^{-1}; b) at the critical angle a power-law distribution of slidings is obtained: $A(\lambda) \sim \lambda^{-3/2}$. Our analytical results are confirmed by numerical simulation, and are in partial agreement with the reported experimental results. We discuss the possible reasons for the remaining discrepancies.Comment: 8 pages, 8 figures, submitted to Phys. Rev.

Epidemiological situation of bovine brucellosis in the State of São Paulo, Brazil

Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina no Estado de São Paulo. O Estado foi estratificado em sete circuitos produtores de bovinos, e 150 rebanhos com atividade reprodutiva foram aleatoriamente selecionados em cada um deles. No total, foram amostrados 1.073 rebanhos. Foram aletoriamente coletadas amostras de soro de 10 ou 15 fêmeas bovinas com idade ³24 meses, totalizando 8.761 animais. Os soros foram submetidos a um protocolo de testes em série, tendo o teste do antígeno acidificado tamponado como método de triagem e o da fixação de complemento como confirmatório. A prevalência estimada de rebanhos com pelo menos um animal soropositivo foi de 9,7% [7,8-11,6%], enquanto a prevalência estimada de animais soropositivos foi de 3,8% [0,7-6,9%], no Estado. Em cada rebanho foi aplicado um questionário epidemiológico para avaliar o grau de associação de possíveis fatores de risco (odds ratio, OR) com a doença. Propriedades com 87 ou mais bovinos (OR= 2,25) e compra de reprodutores (OR= 1,56) foram as variáveis mais associadas à condição de foco de brucelose. ____________________________________________________________________________________________________________ ARQUIVOA study to characterize the epidemiological situation of bovine brucellosis in the State of São Paulo was carried out. The state was stratified in seven cattle production regions and 150 herds with reproductive activity were randomly selected within each one. A total of 1,073 herds were sampled. In a second stage, 10 or 15 cows older than 24 month age (in herds with <100 cows and herds ≥100 cows, respectively) were bled at random. A total of 8,761 animals were bled. Sera were tested using a serial testing procedure with the Rose Bengal test as the screening method and the Complement Fixation as the confirmatory method. The estimated prevalence of herds with at least one positive animal was 9.7% [7.8-11.6%], whereas the estimated prevalence of positive cattle was 3.8% [0.7-6.9%] in São Paulo State. An epidemiological questionnaire was applied in each farm, allowing the evaluation of the association of selected risk factors with the disease. The characteristics associated with the brucellosis infected herds were farms with more than 87 bovines (OR= 2.25) and introduction of breeding cattle (OR= 1.56)

A scientific survey on 1550 cases of oral lesions diagnosed in a Brazilian referral center

ABSTRACT The present study aimed to perform an epidemiological survey on the prevalence rate of oral lesions diagnosed in a referral center in Brazil and to establish association between the lesions and the age and gender of the affected patients. This analytical observational study analyzed 3521 medical records of anatomopathological exams of the Pathological Anatomy and Cytopathology Laboratory of the Cancer Hospital of the state of Mato Grosso (Brazil), from December 2011 to September 2015. A total of 1550 relevant medical records was detected. Patients aging between 41 and 60 consisted of 42.84% of the sample. Males were more affected than females (60.13%). Inflammatory processess consisted of the most prevalent diagnosis (43.29%), followed by squamous cell carcinoma (6.06%), and periapical granuloma (5.23%). Oral health public policies must give major attention to Brazilian males aged between the fourth and sixth decades of life in order to improve their quality of life

Genetic Diversity Of Pacu And Piapara Broodstocks In Restocking Programs In The Rivers Paraná And Paranapanema (brazil)

The genetic diversity of Piaractus mesopotamicus (pacu) and Leporinus elongatus (piapara) broodstocks used in restocking programs in the rivers Paraná and Paranapanema is analyzed. One hundred and twenty specimens (two broodstocks of each species) from fish ponds in Palotina PR Brazil and in Salto Grande SP Brazil were assessed. Ten primers produced 96 fragments, comprising 68 (70.83%) and 94 (97.92%) polymorphic fragments for P. mesopotamicus and L. elongatus broodstocks, respectively. Differences (p <0.05) in the frequency of 15 and 27 fragments were detected for each species, without exclusive fragments. Shannon Index (0.347-0.572) and the percentage of polymorphic fragments (57.3%-94.8%) revealed high intra-population genetic variability for all broodstocks. Results of molecular variance analyses (AMOVA) showed that most variations do not lie between the broodstocks but within each broodstock (89%). Genetic (0.088 and 0.142) and identity (0.916 and 0.868) distance rates demonstrated similarity between the broodstocks of each species, corroborated by Fst (0.1023 and 010.27) and Nm (4.18 and 4.33) rates, with a slight genetic difference due to genic flux. High intrapopulation genetic variability and similarity between the broodstocks of each species was also detected, proving a common ancestry.3742365237

ERT and GPR survey of collapsed paleocave systems at the western border of the Potiguar Basin in northeast Brazil

Collapsed paleocave systems are carbonate reservoirs with high internal spatial complexity that are the result of several stages of karst processes. Paleocave-related reservoirs can be spread over large areas with significant thicknesses that are favourable for hydrocarbon exploration. Nevertheless, few studies have provided a detailed understanding of the strong lateral heterogeneity of these reservoirs and their complex karst-controlled development using modern karst terrain analogues. To elucidate this issue, the internal architecture of a collapsed paleocave system has been mapped accurately at the western border of the Potiguar Basin in Northeastern Brazil. The collapsed paleocaves outcrop in an escarpment that delimits the carbonate platform from the transgressive phase of the basin. Electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) sections were acquired parallel and perpendicular to a road cut and served to parameterize the geophysical signatures of the collapsed paleocaves and the host rocks. The collapsed paleocaves were mapped by identifying high-resistivity zones and high-amplitude ground-penetrating radar reflectors. In contrast, the host rocks are marked by low to intermediate resistivity and ground-penetrating radar reflections that range from low amplitude to almost transparent. The resistivity data and the ground-penetrating radar attribute of the rootsquare energy enabled the mapping of the complex spatial distribution of the collapsed paleocaves system. At depths of approximately 20 m, the paleocaves are more spread out and eventually become isolated while sometimes being connected vertically through shafts. However, at shallower levels, the paleocaves are interconnected by ducts or coalesce into a system of paleocaves that are hundreds of metres long over an area of 12000 m2. The results of the study show the detailed internal geometry of this paleocave system at a subseismic scale, which enables the identification of the connectivity pattern among these karst features and the porosity and total volume of the reservoir. This system could serve as an outcrop analogue for other collapsed paleocave carbonate reservoirs worldwide

Cissus Sicyoides: Pharmacological Mechanisms Involved In The Anti-inflammatory And Antidiarrheal Activities

The objective of this study was to evaluate the pharmacological mechanisms involved in anti-inflammatory and antidiarrheal actions of hydroalcoholic extract obtained from the leaves of Cissus sicyoides (HECS). The anti-inflammatory effect was evaluated by oral administration of HECS against acute model of edema induced by xylene, and the mechanisms of action were analysed by involvement of arachidonic acid (AA) and prostaglandin E2 (PGE2). The antidiarrheal effect of HECS was observed and we analyzed the motility and accumulation of intestinal fluid. We also analyzed the antidiarrheal mechanisms of action of HECS by evaluating the role of the opioid receptor, α2 adrenergic receptor, muscarinic receptor, nitric oxide (NO) and PGE2. The oral administration of HECS inhibited the edema induced by xylene and AA and was also able to significantly decrease the levels of PGE2. The extract also exhibited significant anti-diarrheal activity by reducing motility and intestinal fluid accumulation. This extract significantly reduced intestinal transit stimulated by muscarinic agonist and intestinal secretion induced by PGE2. Our data demonstrate that the mechanism of action involved in the anti-inflammatory effect of HECS is related to PGE2. The antidiarrheal effect of this extract may be mediated by inhibition of contraction by acting on the intestinal smoothmuscle and/or intestinal transit. © 2016 by the authors; licensee MDPI, Basel, Switzerland.17

Implementation of dental specialty centers: a descriptive analysis of the current status in the Brazilian territory

ABSTRACT This study aimed to assess the current implementation status of Dental Specialty Centers (Centros de Especialidades Odontológicas - CEO) in Brazil. The sample included CEOs implemented up to November 2015 in the 27 Brazilian federative units. Data were obtained directly from the database of the Informatics Department of the Brazilian Unified Health System, according to the National Registry of Health Facilities (NRHF) of Dental Specialty Centers of all Brazilian regions. Primary care data were also collected from the cities with implemented CEOs, including coverage status of the Family Health Strategy (FHS) and number of Oral Health Teams (OHT) I and II, at 2 collection periods (January 2006 and November 2015). There were 1019 CEOs implemented in Brazil, which were unequally distributed among the Brazilian states, with prevalence of implementation of CEOs type II (n=503, 49.4%). The statistical analysis showed significant difference between the three types of CEO (I, II, and III) and the variables of coverage rate (FHS) and number of teams (OHT I, OHT II) at both data collection periods. Although presenting an evolutionary aspect in the implementation of CEOs, the implementation of medium-complexity care in Brazil is disorganized

Thrips on fabaceous plants and weeds in an ecotone in northeastern Brazil

ABSTRACT: Thrips (Thysanoptera) on 33 species of Fabaceae (ornamental and forage) and some weed species were surveyed in areas of caatinga-cerrado ecotone in northeastern Brazil. Twenty species of thrips were identified, all of which are associated for the first time with the plants sampled in this study, totaling 26 new host associations, based on collections of immatures. Five species are probably new to science, illustrating the diversity of thrips in the region. A few thrips species that also occur as pests in other regions of Brazil are discussed. Our data extend the distribution area of thrips species and provide basic information on their associated plants

New Limonoids from Dictyoloma vandellianum and Sohnreyia excelsa: Chemosystematic considerations

Molecular phylogenetic studies separated and united a group of genera that constituted the Spathelia-Ptaeroxylon clade, in which Dictyoloma and Sohnreyia have been included. Our taxonomic interest in the Dictyoloma vandellianum and Sohnreyia excelsa stimulated an investigation of both species searching for limonoids. Leaves from D. vandellianum afforded the new limonoid 1,2-dihydro-1α-hydroxy-8,30-epoxy-cneorin R, and heartwood yielded the new rearranged limonoid dictyolomin. Leaves from S. excelsa afforded the new protolimonoid 3β-angeloyloxy-7α,24,25-trihydroxy-21,23-oxide-14,18-cycloapotirucall-21-methoxycetal and the new cycloheptanyl ring C limonoid with carbonate substituent and named as sohnreyolide. The new limonoids from Sohnreyia and Dictyoloma show similarities with those from Rutaceae and Meliaceae, providing support for moving Spathelia-Ptaeroxylon clade near to these associated large families. ©2019 Sociedade Brasileira de Química