Design of 300 GHz Combined Doubler/Subharmonic Mixer Based on Schottky Diodes with Integrated MMIC Based Local Oscillator

In this paper the design and experimental characterization of a combined doubler-subharmonic mixer based on Schottky diodes which uses a 75 GHz MMIC based local oscillator is presented. This solution integrates in the same substrate the doubler and the mixer, which share the same metallic packaging with the local oscillator. The prototype has been fabricated and measured. For characterization, the Y-Factor technique has been used and the prototype yields a best conversion loss and equivalent noise temperature of 11 dB and 1976 K, respectively, at 305 GHz. This performance is close to the state of the art, and shows the potential of this approach, which allows a significant reduction in terms of size and volume.

Evaluation of the factor of enrichment of atmospheric particulate matter in the Campus of UFMG, Belo Horizonte

The particulate matter present in the atmospheric air of large cities is one of the pollutants that causes great environmental risks. Due to their composition of solids and liquids varying in size, shape, composition and origin, they have an impact on the health of the exposed population, agriculture, forests and acidification of lakes. In this scenario, the present work had as objective to evaluate the concentration of the 10-micrometer particulate matter, commonly called PM10, and the elementary concentrations in air filters whose sampling was carried out at the Campus of the Federal University of Minas Gerais. For this, a high-volume sampler was used to collect the particulate matter. The elementary concentration of the particulate matter was determined via neutron activation analysis, method k0. Applying the enrichment factor technique, the influence of anthropogenic sources at the sampled site was investigated. The results showed anthropogenic interferences of zinc, sodium, chromium and iron and a geogenic impoverishment of cobalt.

Addressing reverse inference in structural brain alterations

In neuroimaging with reverse inferences we can infer the involvement of cognitive processes from certain patterns of brain activity. Still, the same reasoning holds if we substitute “brain activity” with “brain alteration” and “cognitive process” with “brain disorder”. To assess the involvement of a certain alteration pattern in a brain disorder we used the Bayes’ factor technique on voxel-based morphometry data of schizophrenia and Alzheimer’s disease. This technique allows to calculate the ratio between the likelihoods of two alternative hypotheses (in our case, that the alteration of the voxel is specific for the brain disorder under scrutiny or that the alteration is not specific). We then performed temporal simulations of the alteration spread associated with different pathologies. The Bayes’ factor values calculated on these simulated data were able to reveal that the areas which are more specific to a certain disease are also the ones to be early altered.