43 resultados para Diffusion Processes with Memory and Central Drift in a Potential Well


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Most museums, libraries, and archives throughout the world have to deal with paper damaged by iron gall ink. For more than a decade international research has been devoted to the topic in an attempt to provide practical treatments for objects and formulate guidelines for the preservation of iron gall ink collections. A working group of conservators in South and Central America and the Caribbean have developed a program to disseminate research findings, collect data about the condition of iron gall ink collections in their countries and identify imminent training needs. The goal of this project is to combine the latest research with existing and acceptable conservation practices and share information about risk management, proper housing, examination and treatment of iron gall ink inscribed artefacts-at risk. Communications among colleagues were established to learn more about the current resources available in collections from various countries.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Shifting cultivation in the humid tropics is incredibly diverse, yet research tends to focus on one type: long-fallow shifting cultivation. While it is a typical adaptation to the highly-weathered nutrient-poor soils of the Amazonian terra firme, fertile environments in the region offer opportunities for agricultural intensification. We hypothesized that Amazonian people have developed divergent bitter manioc cultivation systems as adaptations to the properties of different soils. We compared bitter manioc cultivation in two nutrient-rich and two nutrient-poor soils, along the middle Madeira River in Central Amazonia. We interviewed 249 farmers in 6 localities, sampled their manioc fields, and carried out genetic analysis of bitter manioc landraces. While cultivation in the two richer soils at different localities was characterized by fast-maturing, low-starch manioc landraces, with shorter cropping periods and shorter fallows, the predominant manioc landraces in these soils were generally not genetically similar. Rather, predominant landraces in each of these two fertile soils have emerged from separate selective trajectories which produced landraces that converged for fast-maturing low-starch traits adapted to intensified swidden systems in fertile soils. This contrasts with the more extensive cultivation systems found in the two poorer soils at different localities, characterized by the prevalence of slow-maturing high-starch landraces, longer cropping periods and longer fallows, typical of previous studies. Farmers plant different assemblages of bitter manioc landraces in different soils and the most popular landraces were shown to exhibit significantly different yields when planted in different soils. Farmers have selected different sets of landraces with different perceived agronomic characteristics, along with different fallow lengths, as adaptations to the specific properties of each agroecological micro-environment. These findings open up new avenues for research and debate concerning the origins, evolution, history and contemporary cultivation of bitter manioc in Amazonia and beyond.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Polymorphonuclear leukocyte (PMNL) apoptosis is central to the successful resolution of inflammation. Since Somatic Cell Count (SCC) is an indicator of the mammary gland's immune status, this study sought to clarify the influence that these factors have on each other and on the evolution of the inflammatory process. Milk samples were stained with annexin-V, propidium iodide (PI), primary antibody anti-CH138A. Negative correlation between SCC and PMNL apoptosis was found, and a statistical difference between high SCC group and low SCC group was observed concerning the rate of viable PMNL, apoptotic PMNL, necrotic PMNL and necrotic and/or apoptotic PMNL. Overall, the high cellularity group presented lower proportions of CH138+ cells undergoing apoptosis and higher proportions of viable and necrotic CH138+ cells. Thus, it can be concluded that PMNL apoptosis and SCC are related factors, and that in high SCC, milk apoptosis is delayed. Although there is a greater amount of active phagocytes in this situation, apoptosis' anti-inflammatory effects are decreased, while necrosis' pro-inflammatory effects are increased, which can contribute to chronic inflammation.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This paper studies the average control problem of discrete-time Markov Decision Processes (MDPs for short) with general state space, Feller transition probabilities, and possibly non-compact control constraint sets A(x). Two hypotheses are considered: either the cost function c is strictly unbounded or the multifunctions A(r)(x) = {a is an element of A(x) : c(x, a) <= r} are upper-semicontinuous and compact-valued for each real r. For these two cases we provide new results for the existence of a solution to the average-cost optimality equality and inequality using the vanishing discount approach. We also study the convergence of the policy iteration approach under these conditions. It should be pointed out that we do not make any assumptions regarding the convergence and the continuity of the limit function generated by the sequence of relative difference of the alpha-discounted value functions and the Poisson equations as often encountered in the literature. (C) 2012 Elsevier Inc. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Background: Several parameters are associated with high bone mineral density (BMD), such as overweight, black background, intense physical activity (PA), greater calcium intake and some medications. The objectives are to evaluate the prevalence and the main aspects associated with high BMD in healthy women. Methods: After reviewing the database of approximately 21,500 BMD scans performed in the metropolitan area of Sao Paulo, Brazil, from June 2005 to October 2010, high BMD (over 1400 g/cm(2) at lumbar spine and/or above 1200 g/cm2 at femoral neck) was found in 421 exams. Exclusion criteria were age below 30 or above 60 years, black ethnicity, pregnant or obese women, disease and/or medications known to interfere with bone metabolism. A total of 40 women with high BMD were included and matched with 40 healthy women with normal BMD, paired to weight, age, skin color and menopausal status. Medical history, food intake and PA were assessed through validated questionnaires. Body composition was evaluated through a GE-Lunar DPX MD + bone densitometer. Radiography of the thoracic and lumbar spine was carried out to exclude degenerative alterations or fractures. Biochemical parameters included both lipid and hormonal profiles, along with mineral and bone metabolism. Statistical analysis included parametric and nonparametric tests and linear regression models. P < 0.05 was considered significant. Results: The mean age was 50.9 (8.3) years. There was no significant difference between groups in relation to PA, smoking, intake of calcium and vitamin D, as well as laboratory tests, except serum C-telopeptide of type I collagen (s-CTX), which was lower in the high BMD group (p = 0.04). In the final model of multivariate regression, a lower fat intake and body fatness as well a better profile of LDL-cholesterol predicted almost 35% of high BMD in women. (adjusted R2 = 0.347; p < 0.001). In addition, greater amounts of lean mass and higher IGF-1 serum concentrations played a protective role, regardless age and weight. Conclusion: Our results demonstrate the potential deleterious effect of lipid metabolism-related components, including fat intake and body fatness and worse lipid profile, on bone mass and metabolism in healthy women.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Objective To evaluate the changes in tissue perfusion parameters in dogs with severe sepsis/septic shock in response to goal-directed hemodynamic optimization in the ICU and their relation to outcome. Design Prospective observational study. Setting ICU of a veterinary university medical center. Animals Thirty dogs with severe sepsis or septic shock caused by pyometra who underwent surgery and were admitted to the ICU. Measurements and Main Results Severe sepsis was defined as the presence of sepsis and sepsis-induced dysfunction of one or more organs. Septic shock was defined as the presence of severe sepsis plus hypotension not reversed with fluid resuscitation. After the presumptive diagnosis of sepsis secondary to pyometra, blood samples were collected and clinical findings were recorded. Volume resuscitation with 0.9% saline solution and antimicrobial therapy were initiated. Following abdominal ultrasonography and confirmation of increased uterine volume, dogs underwent corrective surgery. After surgery, the animals were admitted to the ICU, where resuscitation was guided by the clinical parameters, central venous oxygen saturation (ScvO2), lactate, and base deficit. Between survivors and nonsurvivors it was observed that the ScvO2, lactate, and base deficit on ICU admission were each related independently to death (P = 0.001, P = 0.030, and P < 0.001, respectively). ScvO2 and base deficit were found to be the best discriminators between survivors and nonsurvivors as assessed via receiver operator characteristic curve analysis. Conclusion Our study suggests that ScvO2 and base deficit are useful in predicting the prognosis of dogs with severe sepsis and septic shock; animals with a higher ScvO2 and lower base deficit at admission to the ICU have a lower probability of death.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This paper is concerned with the energy decay for a class of plate equations with memory and lower order perturbation of p-Laplacian type, utt+?2u-?pu+?0tg(t-s)?u(s)ds-?ut+f(u)=0inOXR+, with simply supported boundary condition, where O is a bounded domain of RN, g?>?0 is a memory kernel that decays exponentially and f(u) is a nonlinear perturbation. This kind of problem without the memory term models elastoplastic flows.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Stress is the most commonly reported precipitating factor for seizures in patients with epilepsy. Despite compelling anecdotal evidence for stress-induced seizures, animal models of the phenomena are sparse and possible mechanisms are unclear. Here, we tested the hypothesis that increased levels of the stress-associated hormone corticosterone ( CORT) would increase epileptiform activity and spontaneous seizure frequency in mice rendered epileptic following pilocarpine-induced status epilepticus. We monitored video-EEG activity in pilocarpine-treated mice 24/7 for a period of four or more weeks, during which animals were serially treated with CORT or vehicle. CORT increased the frequency and duration of epileptiform events within the first 24 hours of treatment, and this effect persisted for up to two weeks following termination of CORT injections. Interestingly, vehicle injection produced a transient spike in CORT levels - presumably due to the stress of injection - and a modest but significant increase in epileptiform activity. Neither CORT nor vehicle treatment significantly altered seizure frequency; although a small subset of animals did appear responsive. Taken together, our findings indicate that treatment of epileptic animals with exogenous CORT designed to mimic chronic stress can induce a persistent increase in interictal epileptiform activity.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Clinical and experimental evidence suggest that estrogens have a major impact on cognition, presenting neurotrophic and neuroprotective actions in regions involved in such function. In opposite, some studies indicate that certain hormone therapy regimens may provoke detrimental effects over female cognitive and neurological function. Therefore, we decided to investigate how estrogen treatment would influence cognition and depression in different ages. For that matter, this study assessed the effects of chronic 17 beta-estradiol treatment over cognition and depressive-like behaviors of young (3 months old), adult (7 months old) and middle-aged (12 months old) reproductive female Wistar rats. These functions were also correlated with alterations in the serotonergic system, as well as hippocampal BDNF. 17 beta-Estradiol treatment did not influence animals' locomotor activity and exploratory behavior, but it was able to improve the performance of adult and middle-aged rats in the Morris water maze, the latter being more responsive to the treatment. Young and adult rats displayed decreased immobility time in the forced swimming test, suggesting an effect of 17 beta-estradiol also over such depressive-like behavior. This same test revealed increased swimming behavior, triggered by serotonergic pathway, in adult rats. Neurochemical evaluations indicated that 17 beta-estradiol treatment was able to increase serotonin turnover rate in the hippocampus of adult rats. Interestingly, estrogen treatment increased BDNF levels from animals of all ages. These findings support the notion that the beneficial effects of 17 beta-estradiol over spatial reference memory and depressive-like behavior are evident only when hormone therapy occurs at early ages and early stages of hormonal decline. (C) 2011 Elsevier B.V. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Despite advances in our understanding of the mechanisms involved in sex determination and differentiation, the specific roles of many genes in these processes are not completely understood in humans. Both DMRT1 and FGF9 are among this group of genes. Dmrt1 controls germ cell differentiation, proliferation, migration and pluripotency and Sertoli cell proliferation and differentiation. Fgf9 has been considered a critical factor in early testicular development and germ cell survival in mice. We screened for the presence of DMRT1 and FGF9 mutations in 33 patients with 46,XY gonadal dysgenesis. No deletions in either DMRT1 or FGF9 were identified using the MLPA technique. Eight allelic variants of DMRT1 were identified, and in silico analysis suggested that the novel c.968-15insTTCTCTCT variant and the c.774G>C (rs146975077) variant could have potentially deleterious effects on the DMRT1 protein. Nine previously described FGF9 allelic variants and six different alleles of the 3' UTR microsatellite were identified. However, none of these DMRT1 or FGF9 variants was associated with increased 46,XY gonadal dysgenesis. In conclusion, our study suggests that neither DMRT1 nor FGF9 abnormalities are frequently involved in dysgenetic male gonad development in patients with non-syndromic 46,XY disorder of sex development. (C) 2012 Published by Elsevier Masson SAS.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Background Split-hand/foot malformation (SHFM)-also known as ectrodactyly-is a congenital disorder characterised by severe malformations of the distal limbs affecting the central rays of hands and/or feet. A distinct entity termed SHFLD presents with SHFM and long bone deficiency. Mouse models suggest that a defect of the central apical ectodermal ridge leads to the phenotype. Although six different loci/mutations (SHFM1-6) have been associated with SHFM, the underlying cause in a large number of cases is still unresolved. Methods High resolution array comparative genomic hybridisation (CGH) was performed in patients with SHFLD to detect copy number changes. Candidate genes were further evaluated for expression and function during limb development by whole mount in situ hybridisation and morpholino knock-down experiments. Results Array CGH showed microduplications on chromosome 17p13.3, a locus previously associated with SHFLD. Detailed analysis of 17 families revealed that this copy number variation serves as a susceptibility factor for a highly variable phenotype with reduced penetrance, particularly in females. Compared to other known causes for SHFLD 17p duplications appear to be the most frequent cause of SHFLD. A similar to 11.8 kb minimal critical region was identified encompassing a single gene, BHLHA9, a putative basic loop helix transcription factor. Whole mount in situ hybridisation showed expression restricted to the limb bud mesenchyme underlying the apical ectodermal ridge in mouse and zebrafish embryos. Knock down of bhlha9 in zebrafish resulted in shortening of the pectoral fins. Conclusions Genomic duplications encompassing BHLHA9 are associated with SHFLD and non-Mendelian inheritance characterised by a high degree of non-penetrance with sex bias. Knock-down of bhlha9 in zebrafish causes severe reduction defects of the pectoral fin, indicating a role for this gene in limb development.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In this Letter we report the first results on pi(+/-), K-+/-, p, and (p) over bar production at midrapidity (vertical bar y vertical bar < 0.5) in central Pb-Pb collisions at root s(NN) = 2.76 TeV, measured by the ALICE experiment at the LHC. The p(T) distributions and yields are compared to previous results at root s(NN) = 200 GeV and expectations from hydrodynamic and thermal models. The spectral shapes indicate a strong increase of the radial flow velocity with root s(NN), which in hydrodynamic models is expected as a consequence of the increasing particle density. While the K/pi ratio is in line with predictions from the thermal model, the p/pi ratio is found to be lower by a factor of about 1.5. This deviation from thermal model expectations is still to be understood.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We show how to construct a topological Markov map of the interval whose invariant probability measure is the stationary law of a given stochastic chain of infinite order. In particular we characterize the maps corresponding to stochastic chains with memory of variable length. The problem treated here is the converse of the classical construction of the Gibbs formalism for Markov expanding maps of the interval.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

An association between memory and executive dysfunction (ED) has been demonstrated in patients with mixed neurological disorders. We aimed to investigate the impact of ED in memory tasks of children with temporal lobe epilepsy (TLE). We evaluated 36 children with TLE and 28 controls with tests for memory, learning, attention, mental flexibility, and mental tracking. Data analysis was composed of comparison between patients and controls in memory and executive function; correlation between memory and executive function tests; and comparison between patients with mild and severe ED in memory tests. Children with TLE had worse performance in focused attention, immediate and delayed recall, phonological memory, mental tracking, planning, and abstraction. Planning, abstraction, and mental tracking were correlated with visual and verbal memory. Children with severe ED had worse performance in verbal and visual memory and learning tests. This study showed that ED was related to memory performance in children with TLE. (C) 2012 Elsevier Inc. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Background: Cytokines secreted by the adipose tissue influence inflammation and insulin sensitivity, and lead to metabolic disturbances. How certain single-nucleotide polymorphisms (SNPs) interfere on lifestyle interventions is unclear. We assessed associations of selected SNPs with changes induced by a lifestyle intervention. Methods: This 9-month intervention on diet and physical activity included 180 Brazilians at high cardiometabolic risk, genotyped for the TNF-alpha -308 G/A, IL-6 -174 G/C and AdipoQ 45 T/G SNPs. Changes in metabolic and inflammatory variables were analyzed according to these SNPs. Individuals with at least one variant allele were grouped and compared with those with the reference genotype. Results: In the entire sample (66.7% women; mean age 56.5 +/- 11.6 years), intervention resulted in lower energy intake, higher physical activity, and improvement in anthropometry, plasma glucose, HOMA-IR, lipid profile and inflammatory markers, except for IL-6 concentrations. After intervention, only variant allele carriers of the TNF-alpha -308 G/A decreased plasma glucose, after adjusting for age and gender (OR 2.96, p = 0.025). Regarding the IL-6 -174 G/C SNP, carriers of the variant allele had a better response of lipid profile and adiponectin concentration, but only the reference genotype group decreased plasma glucose. In contrast to individuals with the reference genotype, carriers of variant allele of AdipoQ 45 T/G SNP did not change plasma glucose, apolipoprotein B, HDL-c and adiponectin concentrations in response to intervention. Conclusion: The TNF alpha -308 G/A SNP may predispose a better response of glucose metabolism to lifestyle intervention. The IL-6 -174 G/C SNP may confer a beneficial effect on lipid but not on glucose metabolism. Our findings reinforce unfavorable effects of the AdipoQ 45 T/G SNP in lipid profile and glucose metabolism after intervention in Brazilians at cardiometabolic risk. Further studies are needed to direct lifestyle intervention to subsets of individuals at cardiometabolic risk.