RESUMO
We report experimental measurements of the absolute total cross sections (TCSs) for electron scattering from 1-butanol at impact energies in the range 80-400 eV. Those measurements were conducted by considering the attenuation of a collimated electron beam, at a given energy, through a gas cell containing 1-butanol, at a given pressure, and through application of the Beer-Lambert law to derive the required TCS. We also report theoretical results using the Independent-Atom Model with Screening Corrected Additivity Rule and Interference approach. Those results include the TCS, the elastic integral cross section (ICS), the ionization total ICS, and the sum over all excitation process ICSs with agreement at the TCS level between our measured and calculated results being encouraging.
RESUMO
We report the results of ab initio calculations for elastic scattering and also for excitation of individual electronic states of para-benzoquinone (pBQ) by the impact of low-energy electrons. The calculations for elastic scattering were performed with the Schwinger multichannel method implemented with pseudopotentials (SMCPP) in the static-exchange (SE) plus polarization (SEP) approximation for energies up to 50 eV. The assignments for the resonance spectrum obtained in this study are, in general, in good agreement with previous results available in the literature. For electronic excitation by electron impact, the SMCPP method with N energetically open electronic states (N open ), at either the static-exchange (N open ch-SE) or the static-exchange-plus-polarisation (N open ch-SEP) approximation, was employed to calculate the scattering amplitudes using a channel coupling scheme that ranges from the 1ch-SEP up to the 89ch-SE level of approximation, depending on the energy of interest. Integral cross sections (ICSs) and differential cross sections (DCSs) were obtained for incident electron energies lying between 15 eV and 50 eV. The study focuses on the influence of multichannel coupling effects for electronically inelastic processes, more specifically, on how the number of excited states included in the open-channel space impacts upon the convergence of the cross sections at intermediate and higher energies. In particular, we found that the magnitude of DCS and ICS results for electronic excitation decreases as more channels are included in the calculations. To the best of our knowledge, there are no other experimental or theoretical ICS or DCS results for excitation into individual electronic states of pBQ available in the literature between 15 and 50 eV against which we might compare the present calculations.
RESUMO
Absolute total cross section (TCS) measurements for electron scattering from 1-propanol molecules are reported for impact energies from 40 to 500 eV. These measurements were obtained using a new apparatus developed at Juiz de Fora Federal University-Brazil, which is based on the measurement of the attenuation of a collimated electron beam through a gas cell containing the molecules to be studied at a given pressure. Besides these experimental measurements, we have also calculated TCS using the Independent-Atom Model with Screening Corrected Additivity Rule and Interference (IAM-SCAR+I) approach with the level of agreement between them being typically found to be very good.
RESUMO
A bimodal age incidence curve has been shown for Hodgkin's disease (HD). In developing countries, the first age incidence peak occurs in childhood; however, this peak is delayed until young adulthood in developed countries. This difference may reflect differences in the age of exposure to infectious agents involved in the development of HD or may suggest different etiological agents. Epstein-Barr virus (EBV) has been implicated in the pathogenesis of a proportion of HD cases. In this study, EBV association was investigated in a series of 55 pediatric HD cases from three geographical locations (United Kingdom, Brazil, and Saudi Arabia) and the relationship between country, age, sex, histological subtype, and EBV positivity was evaluated. EBV was detected in 38 cases using RNA in situ hybridization, Southern blot, or immunohistochemical analysis. No significant difference in EBV positivity by country, age, or sex was observed; however, children under 10 years of age were particularly likely to be EBV-associated. The difference in EBV association in the pediatric group compared with that observed previously for young adult HD was highly statistically significant (P < 0.0001). These results are consistent with the hypothesis that pediatric and young adult HD have different etiologies and suggest that EBV is likely to be involved in the pathogenesis of pediatric HD.
Assuntos
Herpesvirus Humano 4/fisiologia , Doença de Hodgkin/microbiologia , Adolescente , Fatores Etários , Antígenos Virais/análise , Antígenos Virais/metabolismo , Southern Blotting , Brasil/epidemiologia , Criança , Pré-Escolar , Feminino , Herpesvirus Humano 4/genética , Herpesvirus Humano 4/imunologia , Doença de Hodgkin/epidemiologia , Doença de Hodgkin/metabolismo , Humanos , Imuno-Histoquímica , Hibridização In Situ , Incidência , Lactente , Masculino , Modelos Estatísticos , RNA Viral/análise , RNA Viral/genética , Arábia Saudita/epidemiologia , Fatores Sexuais , Reino Unido/epidemiologia , Proteínas da Matriz Viral/análise , Proteínas da Matriz Viral/metabolismoRESUMO
"Mosquitoes don't have green cards", Laurance N. Nickey, MD, says. That is Dr Nickey's way of saying that disease and environmental pollutants do not recognize the political boundary that separates Texas from Mexico. Dr Nickey, director of the El Paso City-County Health District and chairman of Texas Medical Association's Council on Public Health, is a native and lifelong resident of the city. He is an expert on the public health problems that plague El Paso and the other cities along the international border, all of which are exacerbated by abject poverty and a burgeoning population. Dr Nickey works tirelessly to bring these problems to the attention of Texas physicians, legislators, and other opinion leaders because, as he says, "Out here, we feel like we're the forgotten Texans."
Assuntos
Controle de Doenças Transmissíveis , Serviços de Saúde Comunitária , Saúde Global , Doenças Profissionais/prevenção & controle , Poluição Ambiental , Humanos , México , Estados UnidosRESUMO
The in vitro action of sulphasalazine, BW 755-C and indomethacin on phytohemagglutinin P-induced human peripheral blood mononuclear cell activation was studied. Sulphasalazine increased, while indomethacin and BW 755-C decreased, prostaglandin E2 (PGE2) accumulation in activated cultures. When used together with indomethacin or BW 755-C, sulphasalazine did not counteract the inhibition of PGE2 caused by the other two. Sulphasalazine inhibited phytohemagglutinin P-induced cell activation in a concentration-dependent manner even when used together with indomethacin or BW 755-C. BW 755-C inhibited cell activation at 350 microM, whereas at 11 microM it only increased sulphasalazine-induced inhibition. The implications of these findings on the etiopathology of inflammatory bowel disease are discussed.
Assuntos
4,5-Di-Hidro-1-(3-(Trifluormetil)Fenil)-1H-Pirazol-3-Amina/farmacologia , Indometacina/farmacologia , Leucócitos Mononucleares/efeitos dos fármacos , Fito-Hemaglutininas/farmacologia , Sulfassalazina/farmacologia , Dinoprostona/biossíntese , Humanos , Técnicas In Vitro , Doenças Inflamatórias Intestinais/etiologiaRESUMO
The in vitro action of sulphaslazine, BW 755-C and indomethacin on phytohemaglutinin P-induced human peripheral brood mononuclear cell activation was studied. Sulphasalazine increased, while indomethacin and BW 755-C decreased, prostaglandin E2 (PGE2) accumulation in activated cultures. When used together with indomethacin or BW 755-C, sulpjasalazine did not counteract the inhibiton of PGE2 caused by the other two. Sulphasalazine inhibited phytohemagglutinin P-induced cell activation in a concentration-dependent manner even when used together with indomethacin or BW 755-C. BW 755-C inhibited cell activation at 350 micronM, wehreas at 11, whereas at 11 micronM only increased sulphasalazine-induced inhibition. The implications of these findings on the etiopathology of inflammatory bowel disease are discussed