How kinetics drives the two- to three-dimensional transition in semiconductor strained heterostructures: the case of InAs/GaAs(001)

The two- to three-dimensional growth transition in the InAs/GaAs(001) heterostructure has been investigated by atomic force microscopy. The kinetics of the density of three dimensional quantum dots evidences two transition thresholds at 1.45 and 1.59 ML of InAs coverage, corresponding to two separate families, small and large. Based on the scaling analysis, such families are characterized by different mechanisms of aggregation, involving the change of the critical nucleus size. Remarkably, the small ones give rise to a wealth of "monomers" through the erosion of the step edges, favoring the explosive nucleation of the large ones.Comment: 10 pages, 3 figures. Submitted to Phys. Rev. Let

Cultural barriers to effective communication between Indigenous communities and health care providers in Northern Argentina: an anthropological contribution to Chagas disease prevention and control

INTRODUCTION: Ninety percent of the aboriginal communities of Argentina are located in areas of endemic vectorial transmission of Chagas disease. Control activities in these communities have not been effective. The goal of this research was to explore the role played by beliefs, habits, and practices of Pilaga and Wichi indigenous communities in their interaction with the local health system in the province of Formosa. This article contributes to the understanding of the cultural barriers that affect the communication process between indigenous peoples and their health care providers. METHODS: Twenty-nine open ended interviews were carried out with members of four indigenous communities (Pilaga and Wichi) located in central Formosa. These interviews were used to describe and compare these communities' approach to health and disease as they pertain to Chagas as well as their perceptions of Western medicine and its incarnation in local health practice. RESULTS: Five key findings are presented: 1) members of these communities tend to see disease as caused by other people or by the person's violation of taboos instead of as a biological process; 2) while the Pilaga are more inclined to accept Western medicine, the Wichi often favour the indigenous approach to health care over the Western approach; 3) members of these communities do not associate the vector with the transmission of the disease and they have little awareness of the need for vector control activities; 4) indigenous individuals who undergo diagnostic tests and accept treatment often do so without full information and knowledge; 5) the clinical encounter is rife with conflict between the expectations of health care providers and those of members of these communities. CONCLUSION: Our analysis suggests that there is a need to consider the role of the cultural patterning of health and disease when developing interventions to prevent and control Chagas disease among indigenous communities in Northern Argentina. This is especially important when communicating with these communities about prevention and control. These research findings might also be of value to national and provincial agencies in charge of decreasing the rates of Chagas disease among indigenous populations.Fil: Dell Arciprete, Paula. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Braunstein, Jose Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Touris, María Cecilia. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C.G. Malbrán”. Instituto Nacional de Parasitología “Dr. M. Fatala Chabén”; ArgentinaFil: Dinardi, Matias Andres. Universidad Nacional de Tres de Febrero; ArgentinaFil: Llovet, Ignacio Diego. Universidad Nacional de Luján. Departamento de Ciencias Sociales; ArgentinaFil: Sosa-Estani, Sergio Alejandro. Instituto de Efectividad Clínica y Sanitaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C.G. Malbrán”. Instituto Nacional de Parasitología “Dr. M. Fatala Chabén”; Argentin

Peripheral neurological disturbances, autonomic dysfunction, and antineuronal antibodies in adult celiac disease before and after a gluten-free diet

Thirty-two consecutive adult celiac disease (CD) patients (pts), complaining of peripheral neuropathy (12 pts), autonomic dysfunction (17 pts), or both (3 pts), were evaluated to assess the presence of neurological damage (by clinical neurological evaluation and electrophysiological study) and antineuronal antibodies and to assess the effect of a gluten-free diet (GFD) on the course of the neurological symptoms and on antineuronal antibodies. At entry, 12 of 32 (38%) pts showed signs and symptoms of neurological damage: 7 of 12 (58%), peripheral neurological damage; 3 of 12 (25%), autonomic dysfunction; and 2 (17%), both peripheral neurological damage and autonomic dysfunction. The overall TNS score was 105 at entry. Anti-GM1 antibodies were present in 5 of 12 (42%) pts: 3 showed peripheral neurological damage and 2 showed both peripheral neurological damage and autonomic dysfunction. One year after the GFD was started, histological lesions were still present in only 10 of 12 (83%) pts. TNS score was 99, 98, 98, and 101 at the 3rd, 6th, 9th, and 12th month after the GFD was started, so it did not improve throughout the follow-up. None of the pts showed disappearance of antineuronal antibodies throughout the follow-up. We conclude that adult CD patients may show neurological damage and presence of antineuronal antibodies. Unfortunately, these findings do not disappear with a GFD

The yield of air fluorescence induced by electrons

The fluorescence yield for dry air and pure nitrogen excited by electrons is calculated using a combination of well-established molecular properties and experimental data of the involved cross sections. Particular attention has been paid to the role of secondary electrons from ionization processes. At high pressure and high energy, observed fluorescence turns out to be proportional to the ionization cross section which follows the Born-Bethe law. Predictions on fluorescence yields in a very wide interval of electron energies (eV - GeV) and pressures (1 and 1013 hPa) as expected from laboratory measurements are presented. Experimental results at energies over 1 MeV are in very good agreement with our calculations for pure nitrogen while discrepancies of about 20% are found for dry air, very likely associated to uncertainties in the available data on quenching cross sections. The relationship between fluorescence emission, stopping power and deposited energy is discussed.Comment: 27 pages, 12 figures, 64 references. Accepted in Astroparticle Physic