Suscetibilidade de Anticarsia gemmatalis (Hubner) (Lepidoptera: noctuidae) ao metomil.

Anticarsia gemmatalis Hubner (Lepidoptera: Noctuidae) é uma das principais pragas desfolhadoras da cultura da soja. Para monitorar a eficiência do controle químico das populações a um determinado inseticida, é importante que se determine a suscetibilidade natural de diferentes populações. Assim, este trabalho teve por objetivo determinar os níveis de suscetibilidade de A. gemmatalis ao inseticida metomil e verificar sua diferença nas populações de lagartas provenientes de diferentes regiões geográficas. Para o bioensaio foi utilizado o inseticida metomil (Lannate® BR). Foram testadas seis concentrações do inseticida, de maneira a proporcionarem mortalidade entre 5 e 99%. Foi utilizada aplicação tópica na região torácica dorsal da lagarta em final do segundo ínstar, inoculando 1μl da solução com inseticida por lagarta. A avaliação da mortalidade foi realizada 48 horas após aplicação do inseticida. Os valores de CL50 obtidos nas diferentes populações variaram de 0,01960 a 0,03262 μg dose/lagarta. O estudo revelou que ocorre pouca variabilidade na suscetibilidade ao inseticida Metomil entre as populações estudadas

Strong mass effect on ion beam mixing in metal bilayers

Molecular dynamics simulations have been used to study the mechanism of ion beam mixing in metal bilayers. We are able to explain the ion induced low-temperature phase stability and melting behavior of bilayers using only a simple ballistic picture up to 10 keV ion energies. The atomic mass ratio of the overlayer and the substrate constituents seems to be a key quantity in understanding atomic mixing. The critical bilayer mass ratio of $\delta < 0.33$ is required for the occurrence of a thermal spike (local melting) with a lifetime of $\tau > 0.3$ ps at low-energy ion irradiation (1 keV) due to a ballistic mechanism. The existing experimental data follow the same trend as the simulated values.Comment: 4 pages, 4 figures, preprin

Feasibility, drug safety, and effectiveness of etiological treatment programs for Chagas disease in Honduras, Guatemala, and Bolivia: 10-year experience of Médecins Sans Frontières

BACKGROUND: Chagas disease (American trypanosomiasis) is a zoonotic or anthropozoonotic disease caused by the parasite Trypanosoma cruzi. Predominantly affecting populations in poor areas of Latin America, medical care for this neglected disease is often lacking. Médecins Sans Frontières/Doctors Without Borders (MSF) has provided diagnostic and treatment services for Chagas disease since 1999. This report describes 10 years of field experience in four MSF programs in Honduras, Guatemala, and Bolivia, focusing on feasibility protocols, safety of drug therapy, and treatment effectiveness. METHODOLOGY: From 1999 to 2008, MSF provided free diagnosis, etiological treatment, and follow-up care for patients <18 years of age seropositive for T. cruzi in Yoro, Honduras (1999-2002); Olopa, Guatemala (2003-2006); Entre Ríos, Bolivia (2002-2006); and Sucre, Bolivia (2005-2008). Essential program components guaranteeing feasibility of implementation were information, education, and communication (IEC) at the community and family level; vector control; health staff training; screening and diagnosis; treatment and compliance, including family-based strategies for early detection of adverse events; and logistics. Chagas disease diagnosis was confirmed by testing blood samples using two different diagnostic tests. T. cruzi-positive patients were treated with benznidazole as first-line treatment, with appropriate counseling, consent, and active participation from parents or guardians for daily administration of the drug, early detection of adverse events, and treatment withdrawal, when necessary. Weekly follow-up was conducted, with adverse events recorded to assess drug safety. Evaluations of serological conversion were carried out to measure treatment effectiveness. Vector control, entomological surveillance, and health education activities were carried out in all projects with close interaction with national and regional programs. RESULTS: Total numbers of children and adolescents tested for T. cruzi in Yoro, Olopa, Entre Ríos, and Sucre were 24,471, 8,927, 7,613, and 19,400, respectively. Of these, 232 (0.9%), 124 (1.4%), 1,475 (19.4%), and 1,145 (5.9%) patients, respectively, were diagnosed as seropositive. Patients were treated with benznidazole, and early findings of seroconversion varied widely between the Central and South American programs: 87.1% and 58.1% at 18 months post-treatment in Yoro and Olopa, respectively; 5.4% by up to 60 months in Entre Ríos; and 0% at an average of 18 months in Sucre. Benznidazole-related adverse events were observed in 50.2% and 50.8% of all patients treated in Yoro and Olopa, respectively, and 25.6% and 37.9% of patients in Entre Ríos and Sucre, respectively. Most adverse events were mild and manageable. No deaths occurred in the treatment population. CONCLUSIONS: These results demonstrate the feasibility of implementing Chagas disease diagnosis and treatment programs in resource-limited settings, including remote rural areas, while addressing the limitations associated with drug-related adverse events. The variability in apparent treatment effectiveness may reflect differences in patient and parasite populations, and illustrates the limitations of current treatments and measures of efficacy. New treatments with improved safety profiles, pediatric formulations of existing and new drugs, and a faster, reliable test of cure are all urgently needed

Tolerância de Anticarsia gemmatalis Hübner, Pseudoplusia includens (Walker) E Rachiplusia nu (Guenée) à proteína Cry1Ac.

A soja geneticamente modificada com o gene sintetico de Cry1Ac e uma alternativa ao controle quimico de lepidopteros pragas na cultura da soja. Com a introducao da soja Bt, tornam-se necessarios estudos de analise de risco para prevenir a selecao de insetos resistentes e tambem para compreender o nivel de suscetibilidade dos insetos-alvo a proteina Cry1Ac e com isso iniciar um programa de manejo de resistencia. O objetivo deste trabalho foi determinar a suscetibilidade de Anticarsia gemmatalis Hubner, Pseudoplusia includens (Walker) e Rachiplusia nu (Guenee) provenientes do Rio Grande do Sul a proteina Cry1Ac. Para determinar a suscetibilidade foi utilizada a proteina sintetica de Cry1Ac, MVPII (11,14%). Foram testadas sete concentracoes da proteina Cry1Ac, incorporadas na dieta artificial, apos geleificacao, em cada celula foi inoculada uma lagarta neonata. As lagartas foram mantidas na dieta por sete dias, apos esse periodo avaliou-se a mortalidade e o peso das lagartas sobreviventes. Observou-se que, em ordem decrescente de tolerancia, P. includens apresentou menor suscetibilidade (CL50 1,53 &#956;g Cry1Ac.ml-1 de dieta) a proteina Cry1Ac, seguida por R. nu (CL50 0,70 &#956;g Cry1Ac.ml-1) e por ultimo A. gemmatalis, a qual foi a especie com maior suscetibilidade (CL50 0,04 &#956;g Cry1Ac.ml-1)

Quantum-wave evolution in a step potential barrier

By using an exact solution to the time-dependent Schr\"{o}dinger equation with a point source initial condition, we investigate both the time and spatial dependence of quantum waves in a step potential barrier. We find that for a source with energy below the barrier height, and for distances larger than the penetration length, the probability density exhibits a {\it forerunner} associated with a non-tunneling process, which propagates in space at exactly the semiclassical group velocity. We show that the time of arrival of the maximum of the {\it forerunner} at a given fixed position inside the potential is exactly the traversal time, $\tau$. We also show that the spatial evolution of this transient pulse exhibits an invariant behavior under a rescaling process. This analytic property is used to characterize the evolution of the {\it forerunner}, and to analyze the role played by the time of arrival, $3^{-1/2}\tau$, found recently by Muga and B\"{u}ttiker [Phys. Rev. A {\bf 62}, 023808 (2000)].Comment: To be published in Phys. Rev. A (2002

Spin-Parity Analysis of the Centrally produced KsKs system at 800 GeV

Results are presented of the spin-parity analysis on a sample of centrally produced mesons in the reaction (p p -> p_{slow} K_s K_s p_{fast}) with 800 GeV protons on liquid hydrogen. The spin-parity analysis in the mass region between threshold and 1.58 GeV/c^2 shows that the (K_s K_s) system is produced mainly in S-wave. The f_0(1500) is clearly observed in this region. Above 1.58 GeV/c^2 two solutions are possible, one with mainly S-wave and another with mainly D-wave. This ambiguity prevents a unique determination of the spin of the f_J(1710) meson.Comment: 6 pages, including 6 figures. LaTex, uses 'espcrc2.sty'. To appear in LEAP'96 proceeding

Measurements of RF Properties of Thin Film Nb\u3csub\u3e3\u3c/sub\u3eSn Superconducting Multilayers Using a Calorimetric Technique

Results of RF tests of NB3SN thin film samples related to the superconducting multilayer coating development are presented. We have investigated thin film samples of Nb3Sn/Al2O3/Nb with Nb3Sn layer thicknesses of 50 nm and 100 nm using a Surface Impedance Characterization system. These samples were measured in the temperature range 4 K-19 K, where significant screening by Nb3Sn layers was observed below 16-17 K, consistent with the bulk critical temperature of Nb3Sn

Mexico City and the biogeochemistry of global urbanization

Mexico City is far advanced in its urban evolution, and cities in currently developing nations may soon follow a similar course. This paper investigates the strengths and weaknesses of infrastructures for the emerging megacities. The major driving force for infrastructure change in Mexico City is concern over air quality. Air chemistry data from recent field campaigns have been used to calculate fluxes in the atmosphere of the Valley of Mexico, for compounds that are important to biogeochemistry including methane (CH4), carbon monoxide (CO), nonmethane hydrocarbons (NMHCs), ammonia (NH3), sulfur dioxide (SO2), nitrogen oxides (NOx and NOy), soot, and dust. Leakage of liquified petroleum gas approached 10% during sampling periods, and automotive pollutant sources in Mexico City were found to match those in developed cities, despite a lower vehicle-to-person ratio of 0.1. Ammonia is released primarily from residential areas, at levels sufficient to titrate pollutant acids into particles across the entire basin. Enhancements of reduced nitrogen and hydrocarbons in the vapor phase skew the distribution of NOy species towards lower average deposition velocities. Partly as a result, downwind nutrient deposition occurs on a similar scale as nitrogen fixation across Central America, and augments marine nitrate upwelling. Dust suspension from unpaved roads and from the bed of Lake Texcoco was found to be comparable to that occurring on the periphery of the Sahara, Arabian, and Gobi deserts. In addition, sodium chloride (NaCl) in the dust may support heterogeneous chlorine oxide (ClOx) chemistry. The insights from our Mexico City analysis have been tentatively applied to the upcoming urbanization of Asia