Showing papers by "Universidade Federal de Santa Maria published in 1998"

Déficit hídrico e os processos morfológico e fisiológico das plantas

Abstract: Esta breve revisao de literatura tem como objetivo abordar alguns aspectos dos fatores morfologicos e fisiologicos que, direta ou indiretamente, influenciam na habilidade das plantas em adaptar-se a diferentes condicoes de deficit hidrico durante seu crescimento e desenvolvimento. A sensibilidade do desenvolvimento das folhas ao deficit hidrico pode mudar no transcorrer do dia ou nas diferentes estacoes do ano, porem a limitacao de expansao na area foliar pode ser considerada como uma primeira reacao das plantas a esse deficit. Plantas cultivadas sob condicoes adequadas de suprimento hidrico sao, normalmente, menos resistentes ao deficit hidrico e, quando da ocorrencia rapida do deficit hidrico, os mecanismos morfofisiologicos sao severamente afetados, pois a planta necessitaria adaptar-se rapidamente a esta situacao de deficit; entretanto, quando o deficit hidrico ocorre gradualmente e/ou no inicio do ciclo, mais facilmente ocorre a adaptacao das plantas. A tolerância da planta ao deficit hidrico parece ser um importante mecanismo de resistencia para manter o processo produtivo em condicoes de baixa disponibilidade de agua as plantas. "Por isso, a importância de se abordar alguns aspectos dos fatores morfologicos e fisiologicos que influenciam a habilidade das plantas na adaptacao a situacoes de deficit hidrico."

Perfil da automedicação em município do Sul do Brasil

Abstract: OBJETIVO: Caracterizar o usuario de medicamentos, especialmente aquele que se automedica. MATERIAL E METODO: Foram entrevistadas 413 pessoas do Municipio de Santa Maria, Estado do Rio Grande do Sul, Brasil, sobre o consumo de medicamentos no ultimo mes. RESULTADOS: Dos entrevistados, 69,9% utilizaram medicamentos e destes 76,1% o fizeram atraves de automedicacao. Cefaleia (28,8%) foi a principal queixa motivadora de automedicacao. O acido acetilsalicilico foi a droga mais utilizada (25,4%). Dos farmacos utilizados na automedicacao, 51,2% foram indicados por terceiros e 51,7% dessas indicacoes eram prescricoes medicas emitidas em consultas anteriores. CONCLUSAO: Idade, grau de escolaridade e acompanhamento medico periodico correlacionaram-se significativamente com automedicacao.

Cutaneous Pythiosis insidiosi in calves from the Pantanal region of Brazil

Abstract: Two cases of cutaneous Pythiosis insidiosi were diagnosed in cattle from the Pantanal region, Brazil. The lesions were observed in the limbs of two 8-month-old beef calves. Close examination showed local swelling and focal ulceration of the skin. Microscopically, there was multifocal granulomatous dermatitis with intralesional Pythium insidiosum hyphae. The diagnosis was based on the morphological aspects, immunohistochemical findings and culture of the etiologic agent.

MORFOMETRIA DE Cabralea canjerana, EM MATA SECUNDARIA NATIVA DO RIO GRANDE DO SUL

Abstract: Morphometric data, hypsometric ralationship between diameter and height, and equations of shape factor, commercial shape factor and formal height for Cabralea canjerana , in native secondary forest in RS are shown in this paper. Keylwerth’s, Petterson’s and Pollanschutz’s modelss were tested for hypsometric ralationship in three different stages of the forest development. Naslund’s model was tested for all trees by using the stepwise regression procedure. Following the same procedure, Pollanschutz’s model was used for the shape factor and commercial shape factor, and Kennl’s model was used for the formal height. The sums showed that Cabralea canjerana shape factor depends only on its height and commercial shape factor is a function of its height and BHD. Four out of nine of Kennel’s equation coefficients were significant to 95% level of probability. Naslund’s model was the most appropriate to discribe the hypsometric relationship of the studied species.

Modificações em atributos químicos de solo arenoso sob sistema plantio direto

Abstract: O manejo do solo sem as operacoes de lavracao e gradagem nao incorpora os residuos culturais, fertilizantes e corretivos, alterando a distribuicao e disponibilidade dos nutrientes. Este trabalho teve por objetivo avaliar as modificacoes quimicas decorrentes da adocao do sistema plantio direto (SPD) comparativamente ao cultivo convencional (SCC) e ao campo nativo (CN). Em 1995, coletaram-se amostras de um Podzolico Vermelho-Amarelo textura arenosa/argilosa, em quatro profundidades (0-5, 5-10, 10-20 e 20-40 cm), num experimento instalado, em 1989, na Universidade Federal de Santa Maria (RS). Foi utilizado o delineamento em blocos ao acaso com parcelas subdivididas e quatro repeticoes. Determinaram-se o ponto de efeito salino nulo (PESN), as cargas permanentes, as substâncias humicas, o pH em agua, Al e Ca + Mg trocaveis, H + Al, N total e mineral, K da solucao do solo, trocavel e nao-trocavel, e P disponivel, total e orgânico. Calcularam-se a CTC efetiva e a pH 7,0, a saturacao por Al e por bases e a percentagem de P orgânico. Nao houve variacao no PESN em decorrencia dos diferentes sistemas de manejo do solo. A adocao do SPD aumentou o teor de carbono orgânico, de acidos fulvicos e humicos, CTC, disponibilidade de P e K e acidez potencial, especialmente na camada de 0-5 cm, comparativamente ao SCC.

δ-Aminolevulinate Dehydratase Inhibition by 2, 3-Dimercaptopropanol is Mediated by Chelation of Zinc from a Site Involved in Maintaining Cysteinyl Residues in a Reduced State†

Abstract: The mechanisms underlying mouse delta-aminolevulinate dehydratase (ALA-D) inhibition by a chelating agent used in the treatment of heavy metal poisoning, 2,3-dimercaptopropanol (British Anti-Lewisite), were investigated. ALA-D inhibition by 2,3-dimercaptopropanol was totally reversed by 25-100 microM Zn2+, indicating that inhibition was due to chelation of zinc by 2,3-dimercaptopropanol. Our data suggested that zinc bound to a labile site (displaced by 25-40 microM EDTA or 500 microM 2,3-dimercaptopropanol) is involved in maintaining the sulfhydryl groups of ALA-D in a reduced state (essential for enzyme activity), since inhibition by these compounds was reversed by 10 mM dithiotreitol (a reducing agent). On the other hand, 10 mM dithiotreitol did not reverse ALA-D inhibition by a higher concentration of EDTA (100 microM). Accordingly, 2,3-dimercaptopropanol appears to inhibit ALA-D through a mechanism similar to that of low EDTA concentrations. Neither oxidized 2,3-dimercaptopropanol nor reactive oxygen species appeared to contribute for ALA-D inhibition by reduced 2,3-dimercaptopropanol. Taken together, these results suggest that 2,3-dimercaptopropanol inhibits ALA-D by chelating Zn2+ from a labile site that is involved in maintaining enzyme sulfhydryl groups in a reduced state. This site is compatible with the ZnB or Zn beta previously described in mammalian and bacterial ALA-D.

Reheating in the presence of noise

Abstract: Explosive particle production due to parametric resonance is a crucial feature of reheating in inflationary cosmology. Coherent oscillations of the inflaton field act as a periodically varying mass in the evolution equation for matter fields which couple to the inflaton. This in turn results in the parametric resonance instability. Thermal and quantum noise will lead to a nonperiodic perturbation in the mass. We study the resulting equation for the evolution of matter fields and demonstrate that noise (at least if it is temporally uncorrelated) will increase the rate of particle production. We also estimate the limits on the magnitude of the noise for which the resonant behavior is qualitatively unchanged.

Antigenic characterization of Brazilian bovine viral diarrhea virus isolates by monoclonal antibodies and cross-neutralization

Abstract: Nineteen Brazilian isolates of bovine viral diarrhea virus (BVDV) were characterized antigenically with a panel of 19 monoclonal antibodies (mAbs) (Corapi WV, Donis RO and Dubovi EJ (1990) American Journal of Veterinary Research, 55: 1388-1394). Eight isolates were further characterized by cross-neutralization using sheep monospecific antisera. Analysis of mAb binding to viral antigens by indirect immunofluorescence revealed distinct patterns of reactivity among the native viruses. Local isolates differed from the prototype Singer strain in recognition by up to 14 mAbs. Only two mAbs - one to the non-structural protein NS23/p125 and another to the envelope glycoprotein E0/gp48 - recognized 100% of the isolates. No isolate was recognized by more than 14 mAbs and twelve viruses reacted with 10 or less mAbs. mAbs to the major envelope glycoprotein E2/gp53 revealed a particularly high degree of antigenic variability in this glycoprotein. Nine isolates (47.3%) reacted with three or less of 10 E2/gp53 mAbs, and one isolate was not recognized by any of these mAbs. Virus-specific antisera to eight isolates plus three standard BVDV strains raised in lambs had virus-neutralizing titers ranging from 400 to 3200 against the homologous virus. Nonetheless, many antisera showed significantly reduced neutralizing activity when tested against heterologous viruses. Up to 128-fold differences in cross-neutralization titers were observed for some pairs of viruses. When the coefficient of antigenic similarity (R) was calculated, 49 of 66 comparisons (74.24%) between viruses resulted in R values that antigenically distinguish strains. Moreover, one isolate had R values suggesting that it belongs to a distinct serologic group. The marked antigenic diversity observed among Brazilian BVDV isolates should be considered when planning diagnostic and immunization strategies.

Estudos histológico, histoquímico e ultra-estrutural de fígados e linfonodos de bovinos com presença de macrófagos espumosos ("foam cells")

Abstract: Samples of liver, kidney, spleen, and hepatic, mesenteric, retromandibular, prescapular and mediastinic lymph nodes, collected from 12 groups of cattle of different ages from the State of Mato Grosso, were studied. A total of 120 bovines was examined. According to their history, the animals were kept in pastures where Brachiaria decumbens and Brachiaria brizantha were the predominant plants. Grossly there was a yellowish liver which was more evident after 24 hr. fixation with formalin. Hepatic and mesenteric lymph nodes had normal size, however, on the cut surface there were whitish grooves, extending from the cortex to the medular, and multiple small white nodular areas in the medular. Beside these areas there were red, sometimes hemorrhagic, foci. Microscopically all animals had cells with foamy citoplasm in the liver and in the hepatic and mesenteric lymph nodes, often forming multinucleated cells. In the lymph nodes these infiltrates were adjacent to necrotic, hemorrhagic areas. In the liver the foamy cells were irregularly disseminated throughout the parenchyma or formed nodules around the central vein. These cells did not stain with PAS but weakly with oil red. Ultrastructurally foamy cells and hepatocytes showed negative images of crystals involved partially or totally by membranes. Mediastinic, retromandibular and prescapular lymph nodes of the same animals showed no gross and microscopic alterations.

ANTAGONISMO IN VITRO DE Trichoderma spp. A Verticillium dahliae KLEB

Abstract: This work was carried out to test and to select wild strains of Trichoderma spp. with antagonistic ability against Verticillium dahliae. The in vitro assay consisted of the antibiosis technique by assessment of volatile and non-volatile metabilites and hyphal interaction. Forty seven Trichoderma strains were evaluated and twenty strains were selected by their antagonistic ability against V. dahliae. Through the antibiosis test, seven strains of different species T15P and Tal-1 (T. viride); TW6 and CNP311A (T. koningii); CNP17 and TCII (T. harzianum) and Tal-10 (T. aureoviride) inhibited the mycelial growth of V. dahliae due to the production of metabolites. Several kinds of hyphal interference were observed such as coiling and hook formation.

Levantamentos epidemiológicos em saúde bucal: análise da metodologia proposta pela Organização Mundial da Saúde

Abstract: Os levantamentos epidemiologicos sao importantes para o conhecimento da prevalencia e tipologia das doencas bucais, podendo-se a partir dos dados coletados, planejar, executar e avaliar acoes de saude. E necessario, no entanto, que haja rigor metodologico que garanta reprodutibilidade, validade e confiabilidade, e que haja uniformidade de procedimentos para permitir comparacoes nacionais e internacionais. A iniciativa da Organizacao Mundial da Saude (OMS) na assessoria a realizacao de levantamentos tem se mostrado extremamente util, estimulando o estabelecimento de padroes de procedimentos que podem ser utilizados em todos os paises. Em 1991 foi publicada a edicao em portugues da terceira edicao do "Oral Health Surveys - basic methods", de 1987, um manual que objetiva fornecer instrucoes para a realizacao de levantamentos epidemiologicos e tal publicacao passou a servir de base a estudos realizados em diversos locais do Brasil e do mundo. O objetivo deste trabalho, e analisar criticamente a metodologia para Levantamento Epidemiologico em Saude Bucal da OMS, na tentativa de contribuir para o aperfeicoamento da mesma. De acordo com a presente analise, foram encontrados pontos relevantes para consideracao, referentes a amostragem, a calibracao dos examinadores e aos criterios para a avaliacao de saude bucal e necessidades de tratamento. Concluiu-se, em nivel de recomendacao, que, devido ao carater dinâmico do conhecimento cientifico e, levando-se em consideracao as diferencas regionais com relacao ao padrao de desenvolvimento das doencas bucais, as propostas de padronizacao de levantamentos devem ser periodicamente revisadas. E provavel, ainda, que outros pontos importantes nao tenham sido detectados nesta analise, tornando-se premente ampliar esta discussao para toda a comunidade odontologica.

Pulsations and Radial Velocity Variations in Pulsating Ap Stars. I. Analysis of γ Equulei

Abstract: We present precise radial velocity measurements of the pulsational motions on the rapidly oscillating Ap star γ Equulei taken with an iodine absorption cell. These measurements indicate that the pulsational amplitude is higher in those spectral regions dominated by weak lines. A more detailed analysis of the individual lines of Cr, Fe, and Ti indeed shows that the pulsational amplitudes for strong lines are less than 100 m s-1, whereas for weak lines they are above 200 m s-1 and in one case as high as 1000 m s-1. Also, the mean pulsation amplitude derived from chromium and titanium lines is higher than that derived from iron lines. Time series measurements of radial velocity shifts of single lines are a powerful tool for measuring ion distributions on Ap stars, not only as a function of surface location but of depth as well. This kind of measurement will also be useful in checking predictions of diffusion theory since we can now compare how different ions can move up and down along and across magnetic field lines.

Mortes súbitas em bovinos causadas pela ingestão de Mascagnia sp (Malpighiaceae), no Estado de Santa Catarina

Abstract: In the coastal areas of the State of Santa Catarina occurs a disease in cattle characterized by "sudden death". The disease was reproduced in bovines by oral administration of Mascagnia sp. Single doses of 5 g/kg of the fresch leaves of Mascagnia sp caused non-lethal poisoning; single doses of 7,5 g/kg caused lethal poisoning in one of two bovines and doses of 10 g/kg death in two others. In the experiments clinical manifestations were observed when the animals were exercised. They consisted in weakness, swollen jugular vein, slight muscular tremors and sometimes sudden contractions; tachycardia, already observed before the exercise, became more intense. At the end the animals suddenly laid down or fell on their side. The course of poisoning in those two animals which were followed up till death, was 40 and 75 minutes. The highest doses given (15 and 20 g/kg) caused a protratecd course; the animals got slow and apathic, avoiding any movements. They were found dead, 7h45min and 21 hours after the first clinical signs. These two last experiments show the importance of exercise regarding the onset of symptoms and the occurrence of "sudden death". The main post-mortem findings were intense red discoloration of the mucosa of the small intestine and oedema of the gallbladder wall. The main histological alteration was hydropic vacuolar degeneration of the tubular epithelium of the kidney in three of the five bovines which died.

Use of chromium oxide in digestibility studies: variations of the results as a function of the measurement method

Abstract: The objective of the present study was to evaluate the agreement of two methods for the determination of chromium oxide in feed, duodenal contents and faeces in the investigation of feed digestibility. Four Holstein steers fitted with permanent ruminal and duodenal cannulae were used in a 4×4 Latin square design experiment. Steers were fed diets varying in urea content three times daily, restricted at a level equivalent to 2·5% of live body weight (dry matter basis). Faecal and duodenal fluxes of dry matter and nitrogen were estimated using chromium oxide (Cr2O3) as a indigestible marker. The equivalent Cr2O3 concentration in the solution resulting from acid digestion of the samples was measured by chromium determination by simple photometry at 350 nm and by flame atomic absorption spectrometry. Chromium concentrations in feed, duodenal contents and faeces and ruminal and total digestibilities of dry matter and nitrogen were affected by the chromium determination methods used. Despite the fact that the AAS method is more precise and sensible, sometimes its utilisation is limited by availability of equipment. In this situation, the chromium determination by photometric method can be a feasible alternative, since proper corrections in optical density readings are done. © 1998 SCI.

Crescimento de mudas de Eucalyptus saligna Smith em função de diferentes doses de vermicomposto

Abstract: O presente estudo foi conduzido em uma casa de vegetacao do Centro Tecnologico de Silvicultura do Departamento de Ciencias Florestais, da Universidade Federal de Santa Maria, no Rio Grande do Sul, no periodo de janeiro a maio de 1998. O trabalho teve por objetivo avaliar o efeito de diferentes doses de vermicomposto (0; 5,0; 10,0; 15,0 e 20,0 cm3) em tubetes com capacidade de receber aproximadamente 50 cm3 de substrato no crescimento de mudas de Eucalyptus saligna Smith. Para producao das mudas de Eucalyptus saligna o substrato utilizado foi casca decomposta de Pinus sp. mais vermiculita na proporcao volumetrica de 1:1 acrescida de diferentes doses de vermicomposto. A casca de Pinus sp. foi proveniente da Empresa Florestal RIOCELL S.A.. Para elevar o pH a 6,0, utilizou-se CaCO3 e MgCO3 na proporcao de 2:1 (300g:150g). Apos 120 dias da semeadura, verificou-se que as mudas responderam de maneira distinta as doses de vermicomposto. Doses superiores poderiam ainda aumentar a producao das mudas, pois nao houve estabilizacao nas respostas a adicao de vermicomposto. Growth of Eucalyptus saligna Smith seedlings in function of different doses of vermicompost Abstract The current study was conducted in a greenhouse of the Sylviculture Technological Center of Forest Science Department; at Santa Maria Federal University in Rio Grande do Sul from January to May of 1998. The work had as objective to evaluate the effect of difference doses of vermicompost (0; 5.0; 10.0; 15.0 and 20.0 cm3) in containers with capacity of about 50 cm3 of substratum for the growing of Eucalyptus saligna seedlings. The decomposed bark of Pinus sp. and vermiculit, with a volumetric proportion of 1:1 with different doses of vermicompost, were utilized as substratum for the seedling production of Eucalyptus saligna. The bark of Pinus sp. came from the RIOCELL S.A. Forest Company. CaCO3 and MgCO3, with the proportion of 2:1 (300g: 150g), was utilized for the pH correction until achieve the level of 6.0. One hundred and twenty days after seeding, it was verified that the seedlings reacted differently to the vermicompost doses. Higher doses could increase seedlings production because there was not stabilization in the answer to the vermicompost addition.

Polarographic determination of cyanide as nickelcyano complex in blood plasma after selective extraction in a methylene blue impregnated polyethylene column

Abstract: A method for the determination of cyanide in blood plasma by differential pulse polarography (DPP) is described without a drastic acidification of the sample. Cyanide was determined as tetracyanonickelate(II)-anion complex after a microwave-acid assisted cleanup and a selective complex extraction in a polyethylene methylene blue (PE-MB) impregnated column. The cyano complex was eluted from the column with water/acetonitrile and determined by pulse-polarography at –380 mV (Ag/AgCl). The linear range of calibration was obtained from 1.2 to 9.6 μg of cyanide with r = 0.99 and RSD = 9% of 1.2 μg of cyanide. A detection limit of 40 μg L–1 was calculated and the recoveries of cyanide from spiked samples were about 80%. This method was compared with the classical pyridine-pyrazolone method.

Nucleotide hydrolysis in rats submitted to global cerebral ischemia: A possible link between preconditioning and adenosine production*

Abstract: Adenosine, an endogenous neuroprotective agent, can be produced in the synaptic cleft from adenosine triphosphate (ATP) hydrolysis via the concerted action of two enzymes: ATP diphosphohydrolase and 5′-nucleotidase. The aim of the present study was to investigate such enzymatic activities in the hippocampus of rats subjected to single (2- or 10-minute) or double (2+10 minute, with a 24-hour interval in between, named preconditioned group) ischemic episodes. Ischemia was produced by four-vessel occlusion method. Histological analysis showed no cell death in 2-minute ischemia, and up to 90% of pyramidal CA 1 cell loss in the 10-minute ischemic group. As predicted, double ischemic rats displayed a significant cytoprotective effect (around 60%). Preconditioned rats presented a delayed enhancement in ATP diphosphohydrolase activity (for ATP and adenosine diphosphate hydrolysis) after 48 hours of reperfusion. 5′-nucleotidase activity was increased immediately after ischemic insult (for all groups) and after a late reperfusion period (48 hours). We suggest that preconditioning causes delayed changes in enzymatic activities that would conceivably lead to increased adenosine production. This effect could be related to cytoprotection seen in preconditioned rats.

Técnicas experimentais para tomateiro tipo salada sob estufas plásticas

Abstract: An uniformity trial was carried out with tomate plants grown in a plastic greenhouse with an area of 24m x 12m. The total fruit yield of salad tomato cv. Monte Carlo was evaluated during 11 separat harvest. The basic plot was planted with three plants in the same row. The plants were grown in distances of 0.3m in the same row and by 1,0m between rows. All 24 plots were allocated in ten different rows. The results demonstrate that the completely randomized were more adequate with plots smaller than 18 plants in the same row. The yield evaluation in experiments with different traits using a same cultivar in plastic greenhouse should be conducted up to 30% of total yield. This is importam for more experimental precision and budged economy and time. Results showed that the minimal significance difference varies after 30% of the total yield, was harvested for three, nine and eighteen plants in each plot.

Cyanide determination in biological fluids using a microdiffusion method with a flow system and polarographic detection

Abstract: The report describes a method for the automated polarographic determination of cyanide as tetracyanonickelate(II) anion complex in a gas-diffusion flow system. The volatile cyanide, existing in whole blood, plasma and urine samples, was measured after gas-diffusion using 8 × 10–5 mol l–1 hexaaminenickel solution as acceptor. The linear range of calibration, for measurements at the hanging mercury-drop electrode (HMDE), was from 0.1 to 2.0 µg cyanide with r = 0.998. The RSD was, respectively, 3.4 and 1.2% (n = 5) for 0.4 µg cyanide measured with and without the flow-system configuration. Detection limits of 7.4 µg l–1 were calculated using the flow system and the method was compared with the classical method using Cavet flasks. Parameters that affect the cyanide determination in the proposed method, such as acceptor solution, pH, flow rate and temperature, were investigated.

Intoxicação experimental por Baccharis coridifolia (Compositae) em bovinos

Abstract: Thirteen calves were fed single doses varying from 0.5 to 5g/kg of either freshly harvested or dried Baccharis coridifolia. One calf was fed 4 daily doses of 0,5g/kg of the dried plant. Two calves did not receive the plant and served as controls. The plant material was harvested each month from July 1991 to May 1992 and then in March 1993, and was analysed for its content in macrocyclic trichothecenes. When in flower the female and male plant specimens were both analysed and fed separately to calves. The levels of macrocyclic trichothecenes and their glucosides were much higher in the flowering female plants compared with the levels observed in those plants not in flower and in the flowering male plants. Ten calves either died or were euthanatized due to the toxicosis. Two calves fed the female flowering plant got sick and died, while 3 calves fed the flowering male plant did not develop the toxicosis. Clinical signs in the poisoned calves were anorexia, dehydration, ruminal atony, abdominal distension and pain, liquid diarrhea, dry muzzle, imbalance in the hindlimbs and sternal recumbency. Main pathological findings included necrosis of the gastrointestinal tube, particularly in the forestomachs and in the lymphoid tissues except for the thymus. The latter suggests an effect upon the B cells of the lymphoid tissue. The distribution of the lesions in the digestive and lymphoid systems was sistematically determined. It is concluded that the macrocyclic trichothecenes present in the plant account for the lesions observed in the toxicosis and that the female flowering plant is substantially more toxic than the flowering male plants or plants not in flower. This difference in toxicity is due to the difference in macrocyclic trichothecenes contents.

Leishmaniose visceral (Calazar): cinco casos em cães de Santa Maria, Rio Grande do Sul, Brasil

Abstract: Five canine cases of visceral leishmaniasis were diagnosed. All five dogs presented with icterus, intermitent fever, vomition, anorexia and emaciation. The most prominent gross lesions were hemorrhagic gastroenteritis, interstitial pneumonia and splenomegaly. In tissue sections, free and intracellular forms of Leishmania spp were depicted in macrophages and endothelial cells of all organs scanned. Epidemiological survey to detect either the agent or the sandfly was negative.

A Comparison between Different Methods to Estimate the Lateral Dispersion Parameter under Convective Conditions

Abstract: A new formulation for the lateral dispersion parameter is presented. The model is valid for unstable atmospheric conditions and based on the turbulent kinetic energy spectra and Taylor diffusion theory. It has been tested and compared, through an experimental dataset, with other formulations taken from the literature. The statistical evaluation shows that the proposed σy parameterization is suitable for application in advanced air quality regulatory models.

On exponential stability for von Kármán equations in the presence of thermal effects

Abstract: We consider a dynamical von Karman system in the presence of thermal effects. Our model includes the possibility of a rotational inertia term in the system. We show that the total energy of the solution of such system decays exponentially as t → + ∞. The decay rates we obtain are uniform on bounded sets of the energy space. The main ingredients of our method of proof are suitable properties of a decoupled system, the energy method and the compactness of the nonlinear map associated to the von Karman system.