Spatio-temporal modeling of agricultural yield data with an application to pricing crop insurance contracts

This article presents a statistical model of agricultural yield data based on a set of hierarchical Bayesian models that allows joint modeling of temporal and spatial autocorrelation. This method captures a comprehensive range of the various uncertainties involved in predicting crop insurance premium rates as opposed to the more traditional ad hoc, two-stage methods that are typically based on independent estimation and prediction. A panel data set of county-average yield data was analyzed for 290 counties in the State of Parana (Brazil) for the period of 1990 through 2002. Posterior predictive criteria are used to evaluate different model specifications. This article provides substantial improvements in the statistical and actuarial methods often applied to the calculation of insurance premium rates. These improvements are especially relevant to situations where data are limited.

Pricing farm-level agricultural insurance: a Bayesian approach

This paper applies Hierarchical Bayesian Models to price farm-level yield insurance contracts. This methodology considers the temporal effect, the spatial dependence and spatio-temporal models. One of the major advantages of this framework is that an estimate of the premium rate is obtained directly from the posterior distribution. These methods were applied to a farm-level data set of soybean in the State of the Parana (Brazil), for the period between 1994 and 2003. The model selection was based on a posterior predictive criterion. This study improves considerably the estimation of the fair premium rates considering the small number of observations.

Tendência temporal e desigualdades na mortalidade por diarreias em menores de 5 anos

OBJETIVO: Analisar a tendência da mortalidade por diarreia entre menores de 5 anos, no município de Osasco (SP), entre 1980 e 2000. MÉTODOS: Trata-se de estudo observacional com dois delineamentos. Um descritivo, que toma o indivíduo como unidade do estudo, e outro ecológico, analisando agregado populacional que incluiu análise de séries temporais. A fonte de dados foi o sistema de informação de mortalidade do Estado de São Paulo e censos de 1980, 1991 e 2000. Descreveu-se a variação sazonal e para a análise de tendência aplicaram-se modelos log lineares de regressão polinomiais, utilizando-se variáveis sociodemográficas da criança e da mãe. Foram analisadas a evolução de indicadores sociodemográficos do município de 1980 a 2000, as taxas médias de mortalidade por diarreia nos menores de 5 anos e seus diferenciais por distrito nos anos 90. RESULTADOS: Dos 1.360 óbitos, 94,3 e 75,3% atingiram, respectivamente, menores de 1 ano e de 6 meses. O declínio da mortalidade foi de 98,3%, com deslocamento da sazonalidade do verão para o outono. A mediana da idade elevou-se de 2 meses nos primeiros períodos para 3 meses no último. O resíduo de óbitos manteve-se entre filhos de mães de 20 a 29 anos e escolaridade < 8 anos. O risco relativo entre o distrito mais atingido e a taxa média do município diminuiu de 3,4 para 1,3 do primeiro para o segundo quinquênio dos anos 90. CONCLUSÃO: Nossos resultados apontam uma elevação da idade mais vulnerável e a provável mudança do agente mais frequentemente associado ao óbito por diarreia.

Tendência temporal e desigualdades na mortalidade por diarreias em

Objetivo: Analisar a tendência da mortalidade por diarreia entre menores de 5 anos, no município de Osasco (SP), entre 1980 e 2000. Métodos: Trata-se de estudo observacional com dois delineamentos. Um descritivo, que toma o indivíduo como unidade do estudo, e outro ecológico, analisando agregado populacional que incluiu análise de séries temporais. A fonte de dados foi o sistema de informação de mortalidade do Estado de São Paulo e censos de 1980, 1991 e 2000. Descreveu-se a variação sazonal e para a análise de tendência aplicaram-se modelos log lineares de regressão polinomiais, utilizando-se variáveis sociodemográficas da criança e da mãe. Foram analisadas a evolução de indicadores sociodemográficos do município de 1980 a 2000, as taxas médias de mortalidade por diarreia nos menores de 5 anos e seus diferenciais por distrito nos anos 90. Resultados: Dos 1.360 óbitos, 94,3 e 75,3% atingiram, respectivamente, menores de 1 ano e de 6 meses. O declínio da mortalidade foi de 98,3%, com deslocamento da sazonalidade do verão para o outono. A mediana da idade elevou-se de 2 meses nos primeiros períodos para 3 meses no último. O resíduo de óbitos manteve-se entre filhos de mães de 20 a 29 anos e escolaridade < 8 anos. O risco relativo entre o distrito mais atingido e a taxa média do município diminuiu de 3,4 para 1,3 do primeiro para o segundo quinquênio dos anos 90. Conclusão: Nossos resultados apontam uma elevação da idade mais vulnerável e a provável mudança do agente mais frequentemente associado ao óbito por diarreia

Differential expression of microRNAs in mouse pain models

Background: MicroRNAs (miRNAs) are short non-coding RNAs that inhibit translation of target genes by binding to their mRNAs. The expression of numerous brain-specific miRNAs with a high degree of temporal and spatial specificity suggests that miRNAs play an important role in gene regulation in health and disease. Here we investigate the time course gene expression profile of miR-1, -16, and -206 in mouse dorsal root ganglion (DRG), and spinal cord dorsal horn under inflammatory and neuropathic pain conditions as well as following acute noxious stimulation. Results: Quantitative real-time polymerase chain reaction analyses showed that the mature form of miR-1, -16 and -206, is expressed in DRG and the dorsal horn of the spinal cord. Moreover, CFA-induced inflammation significantly reduced miRs-1 and -16 expression in DRG whereas miR-206 was downregulated in a time dependent manner. Conversely, in the spinal dorsal horn all three miRNAs monitored were upregulated. After sciatic nerve partial ligation, miR-1 and -206 were downregulated in DRG with no change in the spinal dorsal horn. On the other hand, axotomy increases the relative expression of miR-1, -16, and 206 in a time-dependent fashion while in the dorsal horn there was a significant downregulation of miR-1. Acute noxious stimulation with capsaicin also increased the expression of miR-1 and -16 in DRG cells but, on the other hand, in the spinal dorsal horn only a high dose of capsaicin was able to downregulate miR-206 expression. Conclusions: Our results indicate that miRNAs may participate in the regulatory mechanisms of genes associated with the pathophysiology of chronic pain as well as the nociceptive processing following acute noxious stimulation. We found substantial evidence that miRNAs are differentially regulated in DRG and the dorsal horn of the spinal cord under different pain states. Therefore, miRNA expression in the nociceptive system shows not only temporal and spatial specificity but is also stimulus-dependent.

Chemical evolution models for spiral disks: the Milky Way, M31, and M33

Context. The distribution of chemical abundances and their variation with time are important tools for understanding the chemical evolution of galaxies. In particular, the study of chemical evolution models can improve our understanding of the basic assumptions made when modelling our Galaxy and other spirals. Aims. We test a standard chemical evolution model for spiral disks in the Local Universe and study the influence of a threshold gas density and different efficiencies in the star formation rate (SFR) law on radial gradients of abundance, gas, and SFR. The model is then applied to specific galaxies. Methods. We adopt a one-infall chemical evolution model where the Galactic disk forms inside-out by means of infall of gas, and we test different thresholds and efficiencies in the SFR. The model is scaled to the disk properties of three Local Group galaxies (the Milky Way, M31 and M33) by varying its dependence on the star formation efficiency and the timescale for the infall of gas onto the disk. Results. Using this simple model, we are able to reproduce most of the observed constraints available in the literature for the studied galaxies. The radial oxygen abundance gradients and their time evolution are studied in detail. The present day abundance gradients are more sensitive to the threshold than to other parameters, while their temporal evolutions are more dependent on the chosen SFR efficiency. A variable efficiency along the galaxy radius can reproduce the present day gas distribution in the disk of spirals with prominent arms. The steepness in the distribution of stellar surface density differs from massive to lower mass disks, owing to the different star formation histories. Conclusions. The most massive disks seem to have evolved faster (i.e., with more efficient star formation) than the less massive ones, thus suggesting a downsizing in star formation for spirals. The threshold and the efficiency of star formation play a very important role in the chemical evolution of spiral disks. For instance, an efficiency varying with radius can be used to regulate the star formation. The oxygen abundance gradient can steepen or flatten in time depending on the choice of this parameter.

Temporal and spatial distribution of anurans in the Pampa Region (Santa Maria, RS).

The present study aimed to determine the richness, occurrence constancy, reproductive modes. standard of abundance distribution, season of vocalization and to test correlation among climatic variables and activity of vocalization of anurans in a region of the Pampa Biome, Santa Maria, Rio Grande do Sul State. During the period of Novernber/2001 to October/2002 monthly collections were carried out utilizing the `survey at breeding site` method and examination of specimens kept in the Colecao Herpetologica do Setor de Zoologia da Universidade Federal de Santa Maria (ZUFSM). Tire Occurrence of 25 species of anurans was recorded. The anurofauna recorded represents 30% of the species known to Occur in Rio Grande do Sul, and comprises species generally associated with grasslands in this state and neighboring countries. Four reproductive modes were recorded: mode 1 (14 species: 58.3%) mode 11 and 30 (9 species` 37.5%) and mode 24 (1 species; 4.2%). The low diversification of reproductive modes is likely related to the homogeneity of the grassland habitat. Most species were constant or accessory in the Study area and the species abundance distribution patterns fit in the Broken Stick and Log-normal models. characterized by homogeneity of species abundance distribution. Most species showed great plasticity in habitat. but few were plastic in vocalization sites use. There was a weak positive correlation between species richness and precipitation. There was also a weak positive correlation between the abundance of species calling activity and maximum average temperatures. These correlations indicated that, in the study area. the abundance of calling males is more affected by the temperature, and species richness is more affected by precipitation, despite the fact that significantly higher species richness occurs during the hottest period of the year. These results showed that the climatological variables examined were not enough to explain the seasonal occurrence of species, thus the influence of other environmental variables merit to be tested in future studies.

Estrogen effects on pilocarpine-induced temporal lobe epilepsy in rats

Objetive: To evaluate the effects of conjugated equine estrogens (CEE) on the pilocarpine-induced epilepsy in rats. Study design: 40 female rats were divided into: GPC (positive control) presented ""status epilepticus"" (SE) induced by pilocarpine; GOC(ovariectomized control) only castrated; GNC (negative control) received only saline solution; GPE received pilocarpine, presented SE, castrated and received 50 mu g/kg CEE treatment; GPV received pilocarpine, castrated and received propylene glycol (vehicle). The animals were monitored by a video system. At the end of observation, the brains removed for later histologic analysis using Neo-Timm and Nissl methods. Results: The GPE presented a reduction in number of seizures compared to GPV. The Neo-Timm analysis showed that GPV had greater sprouting of mossy fibers, with a denser band in the area of the dentate gyrus hilum compared to GPE. On Nissl staining, GPE showed evident neuronal loss in the CA3 area. GPV presented loss in CA1 and dentate gyrus. Conclusion: Estrogen may have a protecting effect on the central nervous system. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

Comparative neuroanatomical and temporal characterization of FluoroJade-positive neurodegeneration after status epilepticus induced by systemic and intrahippocampal pilocarpine in Wistar rats

The aims of this study were to characterize the spatial distribution of neurodegeneration after status epilepticus (SE) induced by either systemic (S) or intrahippocampal (H) injection of pilocarpine (PILO), two models of temporal lobe epilepsy (TLE), using FluoroJade (FJ) histochemistry, and to evaluate the kinetics of FJ staining in the H-PILO model. Therefore, we measured the severity of behavioral seizures during both types of SE and also evaluated the FJ staining pattern at 12, 24, and 168 h (7 days) after the H-PILO insult. We found that the amount of FJ-positive (FJ+) area was greater in SE induced by S-PILO as compared to SE induced by H-PILO. After SE induced by H-PILO, we found more FJ+ cells in the hilus of the dentate gyrus (DG) at 12 h, in CA3 at 24 h, and in CA1 at 168 h. We found also no correlation between seizure severity and the number of FJ+ cells in the hippocampus. Co-localization studies of FJ+ cells with either neuronal-specific nuclear protein (NeuN) or glial fibrillary acidic protein (GFAP) labeling 24 h after H-PILO demonstrated spatially selective neurodegeneration. Double labeling with FJ and parvalbumin (PV) showed both FJ+/PV+ and FJ+/PV- cells in hippocampus and entorhinal cortex, among other areas. The current data indicate that FJ+ areas are differentially distributed in the two TLE models and that these areas are greater in the S-PILO than in the H-PILO model. There is also a selective kinetics of FJ+ cells in the hippocampus after SE induced by H-PILO, with no association with the severity of seizures, probably as a consequence of the extra-hippocampal damage. These data point to SE induced by H-PILO as a low-mortality model of TLE, with regional spatial and temporal patterns of FJ staining. (C) 2010 Elsevier B.V. All rights reserved.

Neurobiology of panic disorder: From animal models to brain neuroimaging

Evidence from animal models of anxiety has led to the hypothesis that serotonin enhances inhibitory avoidance (related to anxiety) in the forebrain, but inhibits one-way escape (panic) in the midbrain periaqueductal gray (PAG). Stressing the difference between these emotions, neuroendocrinological results indicate that the hypothalamic-pituitary-adrenal axis is activated by anticipatory anxiety, but not by panic attack nor by electrical stimulation of the rat PAG. Functional neuroimaging has shown activation of the insula and upper brain stem (including PAG), as well as deactivation of the anterior cingulated cortex (ACC) during experimental panic attacks. Voxel-based morphometric analysis of brain magnetic resonance images has shown a grey matter volume increase in the insula and upper brain stem, and a decrease in the ACC of panic patients at rest, as compared to healthy controls. The insula and the ACC detect interoceptive stimuli, which are overestimated by panic patients. It is suggested that these brain areas and the PAG are involved in the pathophysiology of panic disorder. (C) 2008 Elsevier Ltd. All rights reserved.

Is dystonic posturing during temporal lobe epileptic seizures the expression of an endogenous anticonvulsant system?

In temporal lobe epilepsy (TLE) seizures, tonic or clonic motor behaviors (TCB) are commonly associated with automatisms, versions, and vocalizations, and frequently occur during secondary generalization. Dystonias are a common finding and appear to be associated with automatisms and head deviation, but have never been directly linked to generalized tonic or clonic behaviors. The objective of the present study was to assess whether dystonias and TCB are coupled in the same seizure or are associated in an antagonistic and exclusive pattern. Ninety-one seizures in 55 patients with TLE due to mesial temporal sclerosis were analyzed. Only patients with postsurgical seizure outcome of Engel class I or II were included. Presence or absence of dystonia and secondary generalization was recorded. Occurrence of dystonia and occurrence of bilateral tonic or clonic behaviors were negatively correlated. Dystonia and TCB may be implicated in exclusive, non-coincidental, or even antagonistic effects or phenomena in TLE seizures. A neural network related to the expression of one behavioral response (e.g., basal ganglia activation and dystonia) might theoretically ""displace"" brain activation or disrupt the synchronism of another network implicated in pathological circuit reverberation and seizure expression. The involvement of basal ganglia in the blockade of convulsive seizures has long been observed in animal models. The question is: Do dystonia and underlying basal ganglia activation represent an attempt of the brain to block imminent secondary generalization? (C) 2007 Elsevier Inc. All rights reserved.

Temporal evolution of epithelial, vascular and interstitial lung injury in an experimental model of idiopathic pulmonary fibrosis induced by butyl-hydroxytoluene

This study was undertaken to test whether the structural remodelling of pulmonary parenchyma can be sequentially altered in a model and method that demonstrate the progression of the disease and result in remodelling within the lungs that is typical of idiopathic pulmonary fibrosis. Three groups of mice were studied: (i) animals that received 3-5-di-tert-butyl-4-hydroxytoluene (BHT) and were killed after 2 weeks (early BHT = 9); (ii) animals that received BHT and were killed after 4 weeks (late BHT = 11); (iii) animals that received corn oil solution (control = 10). The mice were placed in a ventilated Plexiglas chamber with a mixture of pure humidified oxygen and compressed air. Lung histological sections underwent haematoxylin-eosin, immunohistochemistry (epithelial, endothelial and immune cells) and specific staining (collagen/elastic fibres) methods for morphometric analysis. When compared with the control group, early BHT and late BHT groups showed significant decrease of type II pneumocytes, lower vascular density in both and higher endothelial activity. CD4 was increased in late BHT compared with early and control groups, while CD8, macrophage and neutrophil cells were more prominent only in early BHT. The collagenous fibre density were significantly higher only in late BHT, whereas elastic fibre content in late BHT was lower than that in control group. We conclude that the BHT experimental model is pathologically very similar to human usual interstitial pneumonia. This feature is important in the identification of animal models of idiopathic pulmonary fibrosis that can accurately reflect the pathogenesis and progression of the human disease.

Temporal lobe epilepsy and social behavior: An animal model

Social behavior depends on the integrity of social brain circuitry. The temporal lobe is an important part of the social brain, and manifests morphological and functional alterations in autism spectrum disorders (ASD). Rats with temporal lobe epilepsy (TLE), induced with pilocarpine, were subjected to a social discrimination test that has been used to investigate potential animal models of ASD, and the results were compared with those for the control group. Rats with TLE exhibited fewer social behaviors than controls. No differences were observed in nonsocial behavior between groups. The results suggest an important role for the temporal lobe in regulating social behaviors. This animal model might be used to explore some questions about ASD pathophysiology. (c) 2008 Elsevier Inc. All rights reserved.

The sleep-wake cycle in adult rats following pilocarpine-induced temporal lobe epilepsy

The relationship between sleep and epilepsy is both complex and clinically significant. Temporal lobe epilepsy (TLE) influences sleep architecture, while sleep plays an important role in facilitating and/or inhibiting possible epileptic seizures. The pilocarpine experimental model reproduces several features of human temporal lobe epilepsy and is one of the most widely used models in basic research. The aim of the present study was to characterize, behaviorally and electrophysiologically, the phases of sleep-wake cycles (SWC) in male rats with pilocarpine-induced epilepsy. Epileptic rats presented spikes in all phases of the SWC as well as atypical cortical synchronization during attentive wakefulness and paradoxical sleep. The architecture of the sleep-wake phases was altered in epileptic rats, as was the integrity of the SWC. Because our findings reproduce many relevant features observed in patients with epilepsy, this model is suitable to study sleep dysfunction in epilepsy. (C) 2009 Elsevier Inc. All rights reserved.

Evolução temporal da dengue no município de Ribeirão Preto, São Paulo, 1994 a 2003

Este estudo caracteriza-se epidemiológico-descritivo com objetivo de descrever a evolução temporal dos casos de dengue em Ribeirão Preto, São Paulo, no período de 1994 a 2003, segundo mês de ocorrência e sexo. Os dados foram obtidos junto às fichas de notificação compulsória fornecidas pela Vigilância Epidemiológica da Secretaria Municipal de Saúde do município. Foram obtidos os coeficientes de incidência por 100.000 habitantes, segundo estimativas populacionais do Instituto Brasileiro de Geografia e Estatística. O município viveu uma epidemia de dengue no ano de 2001, quando o coeficiente de incidência chegou a 619,65 casos/100.000 habitantes, sendo que dentre os 5.553 casos encontrados no período estudado, 0,07% ocorreram no ano de 1994, 3,68% em 1995, 4,52% em 1996, 2,40% em 1997, 1,82% em 1998, 5,73% em 1999, 3,75% em 2000, 57,37% em 2001, 6,25% em 2002 e, 14,39% em 2003 . Os meses do ano de maior ocorrência da doença foram de janeiro a maio. Em relação à variável sexo, a proporção entre o número de casos foi de aproximadamente 1:1, mostrando pequenas flutuações de casos de dengue entre homens e mulheres, para todo período estudado. Os resultados apontam a necessidade do desenvolvimento de estudos sobre a temática e reforçam o papel das instituições de ensino na questão da dengue no nosso país.