4,771 research outputs found

    Statistical Mechanics Characterization of Neuronal Mosaics

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    The spatial distribution of neuronal cells is an important requirement for achieving proper neuronal function in several parts of the nervous system of most animals. For instance, specific distribution of photoreceptors and related neuronal cells, particularly the ganglion cells, in mammal's retina is required in order to properly sample the projected scene. This work presents how two concepts from the areas of statistical mechanics and complex systems, namely the \emph{lacunarity} and the \emph{multiscale entropy} (i.e. the entropy calculated over progressively diffused representations of the cell mosaic), have allowed effective characterization of the spatial distribution of retinal cells.Comment: 3 pages, 1 figure, The following article has been submitted to Applied Physics Letters. If it is published, it will be found online at http://apl.aip.org

    Cost-effective bioethanol production at low content of nitrogen source from carob syrup

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    Ethanol, as biofuel, has received great interest in the latest decades due to its potential as an alternative transport fuel. Nowadays, ethanol can be produced through fermentative processes, using sugar rich agricultural raw material and it may have a significant role in reducing environmental impact of fossil fuels

    Development of an empirical correlation for Newtonian and non-Newtonian fluids in a stirred tank reactor, to predict oxygen mass transfer rates

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    Most of animal and plant cell cultures present a non-Newtonian behaviour that has a deep effect on the technological performance of bioreactors, affecting the pattern of mixing, the power input required and on the mass and energy transfer as well. In aerobic cultures, the oxygen mass transfer is still a bottleneck, particularly at industrial scale-up, where the high-cell-density biomass and production of metabolites provoke the increase on the viscosity culture, lowering the production yield and eventually losing economical process viability

    Estudo de Bambuí sobre saúde e envelhecimento: metodologia e resultados preliminares de coorte de estudo de idosos no Brasil

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    OBJECTIVE: A cohort study has been designed to identify predictors of adverse health events in the elderly. The methodology of the study and preliminary descriptive results are presented. METHODS: The study population comprises all residents of Bambuí (Minas Gerais, Brazil), aged 60 or more years (n=1.742). From these, 92.2% were interviewed and 85.9% underwent clinical examination, consisting of haematological and biochemical tests, serology for Trypanosoma cruzi, anthropometric and blood pressure measures and electrocardiogram. Aliquots of serum, plasma and DNA were stored for future investigations. The baseline interview included sociodemographic characteristics, self-referred health condition and history of selected diseases, medication use, health service use, source of medical care, physical activities, smoking, drinking and eating habits, reproductive history, physical functioning, life events, social support and mental health. Individuals are being followed up annually. RESULTS: The following characteristics predominated among participants: women (60,0%), married (48.9%) or widowed (35.4%), people living in households with up to 2 residents (73.8%), heads of family (76.7%), people with monthly income between 1.00 and 2.99 Brazilian minimum wages (62.0%) and people with up to 4 years of schooling (89.1%). The median age was 68 years. Among the cohort members, only 1.7% were lost in the first follow-up. CONCLUSIONS: In general, the characteristics of the study population were very similar to those from other epidemiological studies of the elderly based on large Brazilian cities. The small number of losses to follow-up indicates that the choice of Bambuí was adequate, assuring the feasibility of a long term cohort study.OBJETIVO: Um estudo de coorte está sendo desenvolvido para identificar fatores preditores de eventos adversos à saúde em idosos. São apresentados a metodologia do estudo e os resultados descritivos preliminares. MÉTODOS: A população estudada é constituída por todos os residentes na cidade de Bambuí, Minas Gerais, com 60 ou mais anos de idade (n=1.742). Destes, 92,2% foram entrevistados e 85,9% foram submetidos a exames hematológicos e bioquímicos, sorologia para Trypanosoma cruzi , medidas antropométricas e de pressão arterial e eletrocardiograma. Alíquotas de soro, plasma e DNA foram estocadas para futuras investigações. A entrevista da linha de base do estudo incluiu: características sociodemográficas, percepção da saúde e morbidade auto-referida, uso de medicamentos, acesso a serviços de saúde e a planos de saúde, atividades físicas, uso de fumo e de álcool, hábitos alimentares, história reprodutiva, função física, eventos da vida, recursos sociais e saúde mental. Os participantes estão sendo acompanhados anualmente. RESULTADOS: As seguintes características predominaram entre os participantes: mulheres (60%), casados (48,9%) ou viúvos (35,4%), residentes em domicílios com até 2 pessoas (73,8%), chefes de família (76,7%), pessoas com renda mensal entre 1 e 2,99 salários-mínimos (62%) e pessoas com 4 ou menos anos de escolaridade (89,1%). A mediana da idade foi igual a 68 anos. Somente 1,7% dos membros da coorte foram perdidos no primeiro acompanhamento. CONCLUSÕES: Em geral, as características da população estudada foram muito semelhantes às de participantes de outros estudos epidemiológicos sobre envelhecimento, desenvolvidos em grandes cidades brasileiras. A pequena perda para acompanhamento mostra que a escolha de Bambuí foi adequada, garantindo a viabilidade de um estudo prospectivo de longa duração

    Future burden of prostate cancer mortality in Brazil: a population-based study

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    Prostate cancer mortality projections at the nationwide and regional levels to the year 2025 are carried out in this ecological study that is based on an analysis of Brazilian trends between 1996 and 2010. The predictions were made for the period 2011-2025 utilizing the Nordpred program based on the period of 1996-2010, using the age-period-cohort model. A significant increase was observed in the Brazilian rates between 1996 and 2006, followed by a non-significant decrease. The projections indicate a decrease in rates at a national level as well as for the Central, South and Southeast regions. Increases are expected for the North and Northeast regions. In conclusion, a reduction in the mortality rates for prostate cancer in Brazil is expected to the year 2025, as well as for the Central, South and Southeast regions. However, an increase in the absolute number of deaths in all regions is expected due to the anticipated aging of the population

    Allergies and Diabetes as Risk Factors for Dengue Hemorrhagic Fever: Results of a Case Control Study

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    Dengue is an arboviral disease that affects large areas of countries in tropical and subtropical regions of the world. Around 500,000 cases and 22,000 deaths of dengue hemorrhagic fever (DHF)/Dengue Shock Syndrome (DSS), the most severe presentations of this disease, occur annually. It is unclear why some cases of dengue fever (0.5% to 4%) progress to DHF/DSS. There is weak evidence that some diseases could have a role in this process, such as diabetes, hypertension, and allergies. In epidemics most dengue fever cases are sent home as there are too many to be kept in observation, but if it were possible to identify those with a higher risk of progression to DHF, they could be kept for observation, for early detection of signs, symptoms and alterations in laboratory tests suggestive of DHF, to enable timely and effective clinical management and early intervention. We study this issue and we believe that the evidence produced in this study, when confirmed in other studies, suggests that screening criteria might be used to identify adult patients at a greater risk of developing DHF with a recommendation that they remain under observation and monitoring in a hospital

    The Influence of Dentin Age and the Presence of Cracks in Removal of the Root Filling Material

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    Introduction: This study evaluated the removal of the filling material during endodontic retreatment considering the presence of cracks and the dentin age. Methods and Materials: A total of 20 freshly extracted single-rooted teeth were categorized into the following two groups according to the age of the patients: Group Young (Y; aged 18-30 years) and Group Old (O; aged ≥60 years). Each tooth specimen was scanned by microcomputed tomography (micro-CT) subsequently after endodontic retreatment with the Reciproc instruments (REC). The images were analyzed for differences in the volume of dentin cracks and the presence of the filling material in the middle and apical thirds of the teeth among the groups, according to the dentin age. Results: The micro-CT images showed that after retreatment, there were more cracks in the old root dentin than those in the young root dentin, although the difference was not statistically significant (P>0.05). The greatest reduction in the filling material was achieved when the old root dentin with cracks was retreated when compared with that of the young root dentin with cracks, but the difference was not statistically significant (P>0.05). Conclusion: The dentinal age and the presence of cracks were not found to be relevant factors for the removal of the filling material.Keywords: Dentin; Microcomputed Tomography; Retreatmen

    Cardiovascular abnormalities in patients with oral cleft: a clinical-electrocardiographic-echocardiographic study

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    OBJECTIVES: The present study aims to describe the clinical, electrocardiographic, and echocardiographic cardiological findings in a group of patients with oral clefts. METHODS: This is a prospective cross-sectional study on 70 children (age range from 13 days to 19 years) with oral clefts who attended the multidisciplinary program of a university hospital from March 2013 to September 2014. The patients were evaluated by a pediatric cardiologist and underwent detailed anamnesis, physical examination, electrocardiogram, and echocardiogram. RESULTS: Sixty percent of the patients were male; 55.7% presented with cleft lip and palate, and 40.0% presented with health complaints. Comorbidities were found in 44.3%. Relevant pregnancy, neonatal, family and personal antecedents were present in 55.7%, 27.1%, 67.2%, and 24.3% of the patients, respectively. Regarding the antecedents, 15.2% of the patients presented with a cardiac murmur, 49.0% with a familial risk of developing plurimetabolic syndrome, and 6% with family antecedents of rheumatic fever. Electrocardiographic evaluation showed one case of atrioventricular block. Echocardiograms were abnormal in 35.7% of the exams, including 5 cases of mitral valve prolapse — one of which was diagnosed with rheumatic heart disease. CONCLUSION: The finding of a family risk of developing plurimetabolic syndrome and a diagnosis of rheumatic heart disease indicates that patients with oral clefts may be more prone to developing acquired heart disease. Thus, our findings highlight the importance of anamnesis and methodological triangulation (clinical-electrocardiographic-echocardiographic) in the investigation of patients with oral clefts and emphasize that cardiological follow-up to evaluate acquired and/or rhythm heart diseases is necessary. This strategy permits comorbidity prevention and individualized planned treatment

    Low energy elastic and electronically inelastic electron scattering from biomolecules.

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    Reactions initiated by collisions with low-energy secondary electrons has been found to be the prominent\ud mechanism toward the radiation damage on living tissues through DNA strand breaks. Now it is widely accepted\ud that during the interaction with these secondary species the selective breaking of chemical bonds is triggered\ud by dissociative electron attachment (DEA), that is, the capture of the incident electron and the formation\ud of temporary negative ion states [1,2,3]. One of the approaches largely used toward a deeper understanding\ud of the radiation damage to DNA is through modeling of DEA with its basic constituents (nucleotide bases,\ud sugar and other subunits). We have tried to simplify this approach and attempt to make it comprehensible\ud at a more fundamental level by looking at even simple molecules. Studies involving organic systems such as\ud carboxylic acids, alcohols and simple ¯ve-membered heterocyclic compounds are taken as starting points for\ud these understanding. In the present study we investigate the role played by elastic scattering and electronic\ud excitation of molecules on electron-driven chemical processes. Special attention is focused on the analysis of\ud the in°uence of polarization and multichannel coupling e®ects on the magnitude of elastic and electronically\ud inelastic cross-sections. Our aim is also to investigate the existence of resonances in the elastic and electronically\ud inelastic channels as well as to characterize them with respect to its type (shape, core-excited or Feshbach),\ud symmetry and position. The relevance of these issues is evaluated within the context of possible applications\ud for the modeling of discharge environments and implications in the understanding of mutagenic rupture of DNA\ud chains. The scattering calculations were carried out with the Schwinger multichannel method (SMC) [4] and\ud its implementation with pseudopotentials (SMCPP) [5] at di®erent levels of approximation for impact energies\ud ranging from 0.5 eV to 30 eV.\ud References\ud [1] B. Boudai®a, P. Cloutier, D. Hunting, M. A. Huels and L. Sanche, Science 287, 1658 (2000). [2] X. Pan, P.\ud Cloutier, D. Hunting and L. Sanche, Phys. Rev. Lett. 90, 208102 (2003). [3] F. Martin, P. D. Burrow, Z. Cai,\ud P. Cloutier, D. Hunting and L. Sanche, Phys. Rev. Lett. 93, 068101 (2004). [4] K. Takatsuka and V. McKoy,\ud Phys. Rev. A 24, 2437 (1981); ibid. Phys. Rev. A 30, 1734 (1984). [5] M. H. F. Bettega, L. G. Ferreira and\ud M. A. P. Lima, Phys. Rev. A 47, 1111 (1993)
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