Analysis and implementation of a new constant acceleration subcycling algorithm

An algorithm for explicit integration of structural dynamics problems with multiple time steps is proposed that averages accelerations to obtain subcycle states at a nodal interface between regions integrated with different time steps. With integer time step ratios, the resulting subcycle updates at the interface sum to give the same effect as a central difference update over a major cycle. The algorithm is shown to have good accuracy, and stability properties in linear elastic analysis similar to those of constant velocity subcycling algorithms. The implementation of a generalised form of the algorithm with non-integer time step ratios is presented. (C) 1997 by John Wiley & Sons, Ltd.

The melatonin action on stromal stem cells within pericryptal area in colon cancer model under constant light

Constant light (LL) is associated with high incidence of colon cancer. MLT supplementation was related to the significant control of preneoplastic patterns. We sought to analyze preneoplastic patterns in colon tissue from animals exposed to LL environment (14 days; 300 lx), MLT-supplementation (10 mg/kg/day) and DMH-treatment (1,2 dimethylhydrazine; 125 mg/kg). Rodents were sacrificed and MLT serum levels were measured by radioimmunoassay. Our results indicated that LL induced ACF development (p < 0.001) with a great potential to increase the number of CD133(+) and CD68(+) cells (p < 0.05 and p < 0.001). LL also increased the proliferative process (PCNA-Li; p < 0.001) as well as decreased caspase-3 protein (p < 0.001), related to higher COX-2 protein expression (p < 0.001) within pericryptal colonic stroma (PCCS). However, MLT-supplementation controlled the development of dysplastic ACF (p < 0.001) diminishing preneoplastic patterns into PCCS as CD133 and CD68 (p < 0.05 and p < 0.001). These events were relative to decreased PCNA-Li index and higher expression of caspase-3 protein. Thus, MLT showed a great potential to control the preneoplastic patterns induced by LL. (C) 2011 Elsevier Inc. All rights reserved.

Effect of remifentanil hydrochloride administered via constant rate infusion on the minimum alveolar concentration of isoflurane in cats

Objective-To evaluate the effects of increasing doses of remifentanil hydrochloride administered via constant rate infusion (CRI) on the minimum alveolar concentration (MAC) of isoflurane in cats. Animals-6 healthy adult cats. Procedures-For each cat, 2 experiments were performed (2-week interval). On each study day, anesthesia was induced and maintained with isoflurane; a catheter was placed in a cephalic vein for the administration of lactated Ringer`s solution or remifentanil CRIs, and a catheter was placed in the jugular vein for collection of blood samples for blood gas analyses. On the first study day, individual basal MAC (MAC(Basal)) was determined for each cat. On the second study day, 3 remifentanil CRIs (0.25, 0.5, and 1.0 mu g/kg/min) were administered (in ascending order); for each infusion, at least 30 minutes elapsed before determination of MAC (designated as MAC(R0.25`) MAC(R0.5`) and MACR(R1.0`) respectively). A 15-minute washout period was allowed between CRIs. A control MAC (MAC Control) was determined after the last remifentanil infusion. Results-Mean +/- SD MAC(Basal) and MAC(Control) values at sea level did not differ significantly (1.66 +/- 0.08% and 1.52 +/- 0.21%, respectively). The MAC values determined for each remifentanil CRI did not differ significantly. However, MACR(0.25`) MAC(R0.5`) and MAC(R1.0) were significantly decreased, compared with MAC(Basal`) by 23.4 +/- 79%, 29.8 +/- 8.3%, and 26.0 +/- 9.4%, respectively. Conclusions and Clinical Relevance-The 3 doses of remifentanil administered via CRI resulted in a similar degree of isoflurane MAC reduction in adult cats, indicating that a ceiling effect was achieved following administration of the lowest dose. (Am J Vet Res 2009;70:581-588)

Onset of the Henry constant for supercritical adsorption into carbonaceous porous materials

The Henry constant is commonly used as a measure of how strong an adsorbate is attracted towards a solid surface and is regarded as one of the fundamental parameters in adsorption studies. Having a sound basis in thermodynamics, the Henry Law is often used as a criterion to evaluate the validity of adsorption isotherm equations. However, the application of the Henry Law for microporous materials, especially microporous activated carbon, remains questionable. It is the aim of this paper to examine the Henry Law behavior of supercritical adsorbates in carbonaceous pores of different sizes, and to define the conditions for the Henry Law to be applicable for carbonaceous adsorbents.

Surface diffusion of hydrocarbons in activated carbon: Comparison between constant molar flow, differential permeation and differential adsorption bed methods

This paper presents the comparison of surface diffusivities of hydrocarbons in activated carbon. The surface diffusivities are obtained from the analysis of kinetic data collected using three different kinetics methods- the constant molar flow, the differential adsorption bed and the differential permeation methods. In general the values of surface diffusivity obtained by these methods agree with each other, and it is found that the surface diffusivity increases very fast with loading. Such a fast increase can not be accounted for by a thermodynamic Darken factor, and the surface heterogeneity only partially accounts for the fast rise of surface diffusivity versus loading. Surface diffusivities of methane, ethane, propane, n-butane, n-hexane, benzene and ethanol on activated carbon are reported in this paper.

Development and survival of the diamondback moth (Lepidoptera : Plutellidae) at constant and alternating temperatures

Survival and development time from egg to adult emergence of the diamondback moth, Plutella xylostella (L.), were determined at 19 constant and 14 alternating temperature regimes from 4 to 40degreesC. Plutella xylostella developed successfully front egg to adult emergence at constant temperatures from 8 to 32degreesC. At temperatures from 4 to 6degreesC or from 34 to 40degreesC, partial or complete development of individual stages or instars was possible, with third and fourth instars having the widest temperature limits. The insect developed successfully from egg to adult emergence under alternating regimes including temperatures as low as 4degreesC or as high as 38degreesC. The degree-day model, the logistic equation, and the Wang model were used to describe the relationships between temperature and development rate at both constant and alternating temperatures. The degree-day model described the relationships well from 10 to 30degreesC. The logistic equation and the Wang model fit the data well at temperatures 32degreesC. Under alternating regimes, all three models gave good simulations of development in the mid-temperature range, but only the logistic equation gave close simulations in the low temperature range, and none gave close or consistent simulations in the high temperature range. The distribution of development time was described satisfactorily by a Weibull function. These rate and time distribution functions provide tools for simulating population development of P. xylostella over a wide range of temperature conditions.

Nota sobre a infecção natural de Calomys expulsus, Lund, 1841 (Cricetidae-Rodentia) pelo Trypanosoma cruzi

Foi isolada uma amostra de T. cruzi do roedor silvestre, Calomys expulsus, Lund, 1841, capturado no norte do município de Formosa, Goiás, através de inoculações em animais de laboratório, e subseqüente xenodiagnósticos com R. neglectus, T. infestans e P. megistus. A amostra de T. cruzi apresentou patogenicidade muito baixa para os animais inoculados, mas conferiu resistência a reinjecções a cêpa Y de origem humana. As jornias sanguícolas tiveram um comprimento total médio de 21.8 µ e o índice nuclear foi 1.15.

Radiatively induced Lorentz and CPT violation in Schwinger constant field approximation

The Schwinger proper-time method is an effective calculation method, explicitly gauge-invariant and nonperturbative. We make use of this method to investigate the radiatively induced Lorentz- and CPT-violating effects in quantum electrodynamics when an axial-vector interaction term is introduced in the fermionic sector. The induced Lorentz- and CPT-violating Chern-Simons term coincides with the one obtained using a covariant derivative expansion but differs from the result usually obtained in other regularization schemes. A possible ambiguity in the approach is also discussed. (C) 2001 Published by Elsevier Science B.V.

Modeling of the lung impedance using a fractional order ladder network with constant phase elements

The self similar branching arrangement of the airways makes the respiratory system an ideal candidate for the application of fractional calculus theory. The fractal geometry is typically characterized by a recurrent structure. This study investigates the identification of a model for the respiratory tree by means of its electrical equivalent based on intrinsic morphology. Measurements were obtained from seven volunteers, in terms of their respiratory impedance by means of its complex representation for frequencies below 5 Hz. A parametric modeling is then applied to the complex valued data points. Since at low-frequency range the inertance is negligible, each airway branch is modeled by using gamma cell resistance and capacitance, the latter having a fractional-order constant phase element (CPE), which is identified from measurements. In addition, the complex impedance is also approximated by means of a model consisting of a lumped series resistance and a lumped fractional-order capacitance. The results reveal that both models characterize the data well, whereas the averaged CPE values are supraunitary and subunitary for the ladder network and the lumped model, respectively.

Infecção pulmonar fatal por Lagochilascaris sp., provavelmente Lagochilascaris minor Leiper, 1909

É descrito um caso fatal de infecção por Lagochilascaris sp., — provavelmente Lagochilascaris minor Leiper, 1909 —, com localização pulmonar. O paciente, do sexo feminino, oriundo de Curralinho-Estado do Pará, desenvolveu uma pneumonite grave, que lhe acarretou a morte, por insuficiência respiratória, em pouco menos de três meses. À autópsia, numerosas lesões de natureza exsudativa e granulomatosa podiam ser vistas em ambos os pulmões, indicando tuberculose ou infecção micótica pulmonar. Todavia, quando se procedeu ao exame microscópico, ovos, larvas e até uma fêmea grávida do verme foram encontrados nos tecidos, como causa da doença — sempre no interior de granulomas ou de extensas áreas de necrose. Em quase todos os casos, até agora conhecidos, de lagoquilascaríase humana — cerca de 25 —, o parasito se localizava nos tecidos do pescoço, nos seios da face ou sobre a apófise mastóide. Neste caso, pela primeira vez, um representante do gênero Lagochilascaris é referido em sítio bem distinto do habitual, no hospedeiro humano. O achado, por outro lado, dos diferentes estádios evolutivos do helminto, dispersos pelo parênquima pulmonar, além de mostrar a natureza errática do parasitismo, sugere fortemente a existência de um ciclo pulmonar na lagoquilascaríase humana.

A doença de Chagas no Brasil: indícios de sua ocorrência e distribuição até 1909

A doença de Chagas se tornou conhecida do mundo científico a partir de 1909. Dadas suas características clínicas, evidências de sua ocorrência até 1909 são fragmentárias. No entanto, uma análise cuidadosa de escritos médicos e leigos, particularmente do século 19, permitiu tirar algumas conclusões acerca da epidemiologia da doença no Brasil, particularmente no Estado de São Paulo. Possivelmente o acesso a obras raras nos permitirá lançar novas luzes sobre o assunto.

Reinfecção pelo Toxoplasma gondii Nicolle & Manceaux, 1909 em camundongos e gatos: estudo experimental

A reinfecção pelo Toxoplasma gondii foi estudada, experimentalmente, em 27 camundongos albinos e 25 gatos domésticos. A infecção e a reinfecção foram comprovadas por sinais clínicos, anticorpos sangüíneos à reação de Sabin & Feldman > 1/4, recuperação do parasita e, nos gatos, também pela eliminação de oocistos. Nos camundongos a mortalidade foi de 56%. A primo-infecção por cepa de baixa virulência ou a infecção por cepa mais virulenta, atenuada pela sulfamonometoxina, deram proteção à reinfecção por cepa mais virulenta, mortal em poucos dias. Esta proteção foi demonstrada pela sobrevivência de camundongos e menor mortalidade, 12,5'%. Nos gatos a mortalidade foi de 28%, A resposta sorológica à primo-infecção ocorreu em todos. Após a reinfecção houve elevação de títulos em 64% dos gatos, permanência em 32% e queda em 4%. A eliminação de oocistos foi observada em 60% dos gatos e só após inoculação de cistos, por via digestiva. A reeliminação após reinfecção, ocorreu em 25% dos gatos. Não foi observada eliminação após a 3.ª inoculação. Em 88,2% dos gatos houve recuperação do parasita em camundongo, mais freqüente nos linfonodos mesentéricos e no intestino delgado, persistindo neste cerca de 14 meses. Foi constatada certa relação entre o bom estado físico dos gatos e a resposta sorológica, a eliminação e a reeliminação de oocistos. Apesar da persistência de anticorpos sangüíneos a reinfecção experimental dos gatos foi observada, porém a reeliminação de oocistos foi pouco freqüente e em pequena quantidade.

Lagochilascaris minor Leiper, 1909, (Nematoda-Ascaridae) de origem humana

Os autores isolaram e estudaram morfologicamente Lagochilascaris minor Leiper 1909, material obtido na cirurgia de um abscesso cervical direito de um menino de cor branca, com cinco anos de idade, procedente da cidade de Colorado, no Município de Vilhena, em Rondonia-Brasil. É sugerida uma chave para o diagnóstico diferencial das espécies do gênero Lagochilascaris.

Ação "in vitro" do Ivermectin sobre ovos de Lagochilascaris Minor leiper, 1909

Ovos uterinos de fêmeas L. minor, obtidos por eliminação espontânea de abscessos cervicais da paciente W. M. R. (Pequizeiro-GO) - foram postos em contato com solução de Ivermectin nas concentrações de 50, 100, 150, 200 e 250 microgramas. Os resultados demonstraram que a droga em todas as concentrações utilizadas não impediu o desenvolvimento larvário. Entretanto, decorrida a embriogênese houve um processo de desvitalização da larva no interior do ovo caracterizado pela liberação de uma massa amorfa a partir do ovo embrionado. Em ovos do grupo controle houve eclosão de uma larva íntegra com todas as características estruturais de larva de Lagochilascaris.