4,650 research outputs found
Populational fluctuation and spatial distribution of Alphitobius diaperinus (Panzer) (Coleoptera; Tenebrionidae) in a poultry house, Cascavel, Parana state, Brazil.
Abstract Knowledge of the population fluctuation and spatial distribution of pests is fundamental for establishing an appropriate control method. The population fluctuation and spatial distribution of the Alphitobius diaperinus in a poultry house in Cascavel, in the state of Parana, Brazil, was studied between October, 2001 and October 2002. Larvae and adults of the lesser mealworm were sampled weekly using Arends tube traps (n = 22) for six consecutive flock grow-outs. The temperature of the litter and of the poultry house was measured at the same locations of the tube traps. Beetle numbers increased continuously throughout all the sampling dates (average 5,137 in the first week and 18,494 insects on the sixth week). Significantly greater numbers of larvae were collected than adults (1 to 20 times in 95% of the sampling points). There was no correlation between temperature and the number of larvae and adults collected, therefore no fluctuation was observed during the sampling period. The population growth was correlated to litter re-use. The highest temperatures were observed in deep litter. The spatial distribution of larvae and adults in the poultry house was heterogeneous during the whole period of evaluation. Results suggest that monitoring in poultry houses is necessary prior to adopting and evaluating control measures due to the great variability of the insect distribution in the poultry house. Keywords: lesser mealworm, poultry house, temperature, population dynamicbitstream/item/78871/1/ID-27879.pd
Resonant and nonresonant D+ -> K- pi+ l+ nu(l) semileptonic decays
We analyse the semileptonic decay D+ -> K- pi+ l+ nu(l) using an effective
Lagrangian developed previously to describe the decays D -> P l nu(l) and D ->
V l nu(l). Light vector mesons are included in the model which combines the
heavy quark effective Lagrangian and chiral perturbation theory approach. The
nonresonant and resonant contributions are compared. With no new parameters the
model correctly reproduces the measured ratio Gamma(nres)/Gamma(nres + res). We
also present useful nonresonant decay distributions. Finally, a similar model,
but with a modified current which satisfies the soft pion theorems at the
expense of introducing another parameter, is analyzed and the results of the
models are compared.Comment: 17 pages, 3 Postscript figures, standard Latex, extended revision,
title, abstract and text (especially Sec. IV) changed, results unchange
Heavy Quark Symmetry Violation in Semileptonic Decays of D Mesons
The decays of mesons to and final states exhibit
significant deviations from the predictions of heavy-quark symmetry, as one
might expect since the strange quark's mass is of the same order as the QCD
scale. Nonetheless, in order to understand where the most significant effects
might lie for heavier systems (such as and ),
the pattern of these deviations is analyzed from the standpoint of perturbative
QCD and corrections. Two main effects are noted. First, the
perturbative QCD corrections lead to an overall decrease of predicted rates,
which can be understood in terms of production of excited kaonic states.
Second, effects tend to cancel the perturbative QCD
corrections in the case of decay, while they have minimal effect in
decay.Comment: 25 pages (LaTeX) + 7 pages of Postscript figures (included at end),
EFI-92-3
Rare -Decays and Heavy to Light Semileptonic Transitions in the Isgur and Wise Limit
From the experimental branching ratios for and
D^+ --> {\overl K}^{*0}({\overl K}^0) e^+ \nu_e one finds, in the Heavy Quark
Limit of , , larger but consistent with
the actual quoted range . In the same framework one predicts
for .Comment: 9 pages, 1 Figure avalaible on request from [email protected]
Entrance-channel Mass-asymmetry Dependence of Compound-nucleus Formation Time in Light Heavy-ion Reactions
The entrance-channel mass-asymmetry dependence of the compound nucleus
formation time in light heavy-ion reactions has been investigated within the
framework of semiclassical dissipative collision models. the model calculations
have been succesfully applied to the formation of the Ar compound
nucleus as populated via the Be+Si, B+Al,
C+Mg and F+F entrance channels. The shape evolution
of several other light composite systems appears to be consistent with the
so-called "Fusion Inhibition Factor" which has been experimentally observed. As
found previously in more massive systems for the fusion-evaporation process,
the entrance-channel mass-asymmetry degree of freedom appears to determine the
competition between the different mechanisms as well as the time scales
involved.Comment: 12 pages, 3 Figures available upon request, Submitted at Phys. Rev.
Promoting reality awareness in virtual reality through proxemics
Head-Mounted Virtual reality (VR) systems provide full-immersive experiences to users and completely isolate them from the outside world, placing them in unsafe situations. Existing research proposed different alert-based solutions to address this. Our work builds on these studies on notification systems for VR environments from a different perspective. We focus on: (i) exploring alert systems to notify VR users about non-immersed bystanders' in socially related, non-critical interaction contexts; (ii) understanding how best to provide awareness of non-immersed bystanders while maintaining presence and immersion within the Virtual Environment(VE). To this end, we developed single and combined alert cues - leveraging proxemics, perception channels, and push/pull approaches and evaluated those via two user studies. Our findings indicate a strong preference towards maintaining immersion and combining audio and visual cues, push and pull notification techniques that evolve dynamically based on proximity
Intestinal protozoa parasites association with anemia in people from Brazilian western Amazon communities
Introduction: Nowadays intestinal parasitic infection remains an important public health trouble in Latin and South America, emphasizing the Amazon region. Furthermore, intestinal parasites have been considered important factors in etiology of nutritional anemia and malnutrition. Objective: This study aimed to evaluate the intestinal parasitic infection and its possible association with anemia in people from Amazon communities. Methods: The study was a research in documentary records, descriptive, retrospective and cross-sectional, with confirmed cases of parasites infection found in State Hospital of Cacoal-Rondônia, Brazilian Western Amazon. The parameters evaluated were gender, age, race, parasites, hematocrit and hemoglobin. Results: Females where slight higher for the number of cases of parasites occurrence (51%) compared to males (49%) and children had higher parasitic index (43%) followed by adults (37%), teenagers (11%) and seniors (9%). With regards to race, pardos (brown skin color) group was the most affected by the parasites with 69% of cases, followed by caucasians (17%), indians (11%) and blacks (3%). The major parasites diagnosed were Endolimax nana (55%), Giardia lamblia (28%), Entamoeba coli (14%) and Iodamoeba bütschlii (3%). In relation to the association of intestinal parasites and anemia, children had a 60% anemia increase when compared to adults (p <0.05) and the indians increased by 100% anemia when paired against caucasians (p <0.05).Conclusion: Thus, it is suggested that attention should be given to the increase in protozoa parasitic infection prevalence in Amazonian communities and expedite the emergency of improvements in political and sanitation programs of water treatment and waste and sewer management
Ethanol electrooxidation on Pt-Sn and Pt-Sn-W bulk alloys
Ethanol oxidation has been studied on Pt-Sn and Pt-Sn-W electrodes prepared in an arc-melting furnace. Different electrochemical techniques like cyclic voltammetry and chronoamperometry were used to evaluate the catalytic activity of these materials. The electro-oxidation process was also investigated by in situ infrared reflectance spectroscopy in order to determine adsorbed intermediates and reaction products. Experimental results indicated that Pt-Sn and Pt-Sn-W alloys are able to oxidize ethanol mainly to acetaldehyde and acetic acid. Adsorbed CO was also detected, demonstrating the viability of splitting the C-C bond in the ethanol molecule during the oxidation process. The adsorbed CO was further oxidized to CO2.This reaction product was clearly detected by SNIFTIRS. Pt-Sn-W catalyst showed a better electrochemical performance than Pt-Sn that, in it turn, is better than Pt-alone.A oxidação de etanol foi estudada sobre eletrodos Pt-Sn e Pt-Sn-W preparados em forno a arco elétrico. Diferentes técnicas eletroquímicas, tais como voltametria cíclica e cronoamperometria foram utilizadas para avaliar a atividade catalítica desses materiais. O processo de eletro-oxidação também foi investigado in situ por espectroscopia de reflectância na região do infravermelho para determinar intermediários adsorvidos e produtos da reação. Os resultados experimentais indicaram que as ligas Pt-Sn e Pt-Sn-W são capaz de oxidar etanol principalmente para acetaldeído e ácido acético. CO adsorvido também foi detectado, demonstrando a viabilidade do rompimento da ligação C-C na molécula de etanol durante o processo de oxidação. Adicionalmente, o CO adsorvido foi oxidado a CO2. Esse produto de reação foi claramente detectado por SNIFTIRS. O catalisador Pt-Sn-W mostrou um melhor desempenho eletroquímico em relação ao Pt-Sn e este, por sua vez, é melhor do que Pt pura.CAPES - COFECUBCNP
Dinâmica populacional de Ctenarytaina spatulata (Hemiptera: Psyllidae) em Eucaluptus grandis com novos registros de ocorrência.
Dentre os fatores físicos que exercem influência sobre os insetos, os mais importantes são a temperatura, a umidade, luz e o vento. Quanto à temperatura, os insetos, de um modo geral, desenvolvem-se melhor em temperaturas próximas a 25o C, podendo, no entanto, viver numa larga faixa de temperaturas. Dentro da faixa favorável, os insetos apresentam estreitas faixas de melhor desenvolvimento. De forma análoga à temperatura, as exigências de água pelos insetos variam muito, principalmente devido seus hábitos alimentares. A luz é um dos fatores limitantes aos seres vivos, podendo influenciar na reprodução, dispersão, emergência, alimentação e escolha do hospedeiro (BRENNAN & WEINBAUM 2001d). O vento, além de afetar a temperatura e umidade do ambiente, auxilia os insetos nos processos de dispersão e migração, principalmente quando procuram novo habitat, para alimentação e reprodução (LARA, 1979)
A Phenomenological Analysis of Non-resonant Charm Meson Decays
We analyse the consequences of the usual assumption of a constant function to
fit non-resonant decays from experimental Dalitz plot describing charmed meson
decays. We first show, using the decay channel as
an example, how an inadequate extraction of the non-resonant contribution could
yield incorrect measurements for the resonant channels. We analyse how the
correct study of this decay will provide a test for the validity of
factorization in D meson decays. Finally, we show how form factors could be
extracted from non-resonant decays. We particularly discuss about the form
factor that can be measured from the decay. We
emphasize on its relevance for the study of the decay and the extraction of the meson width.Comment: 14 pages, Latex including 6 eps figure
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