Bandwidth aspects in second generation current conveyors

This paper discusses bandwidth problems associated with second-generation current conveyors (CCII). In particular, our work is centered in high-capacitance applications, and has been oriented for wireless optical links and applied physics. We discuss techniques for improving bandwidth in these CCIIs, and develop a new CCII structure with larger bandwidth than traditional circuits. These circuits are then compared in terms of their noise and dynamic range characteristics. A test circuit was developed to verify these different bandwidth behaviors

Majorana bound states in open quasi-1D and 2D systems with transverse Rashba coupling

We study the formation of Majorana states in quasi-1D and 2D square lattices with open boundary conditions, with general anisotropic Rashba coupling, in the presence of an applied Zeeman field and in the proximity of a superconductor. For systems in which the length of the system is very large (quasi-1D) we calculate analytically the exact topological invariant, and we find a rich phase diagram which is strongly dependent on the width of the system. We compare our results with previous results based on a few-band approximation. We also investigate numerically open 2D systems of finite length in both directions. We use the recently introduced generalized Majorana polarization, which can locally evaluate the Majorana character of a given state. We find that the formation of Majoranas depends strongly on the geometry of the system and if the length and the width are comparable no Majorana states can form, however, one can show the formation of "quasi-Majorana" states that have a local Majorana character, but no global Majorana symmetry.Comment: 12 pages, 13 figure

Detectability of f-mode Unstable Neutron Stars by the Schenberg Spherical Antenna

The Brazilian spherical antenna (Schenberg) is planned to detect high frequency gravitational waves (GWs) ranging from 3.0 kHz to 3.4 kHz. There is a host of astrophysical sources capable of being detected by the Brazilian antenna, namely: core collapse in supernova events; (proto)neutron stars undergoing hydrodynamical instability; f-mode unstable neutron stars, caused by quakes and oscillations; excitation of the first quadrupole normal mode of 4-9 solar mass black holes; coalescence of neutron stars and/or black holes; exotic sources such as bosonic or strange matter stars rotating at 1.6 kHz; and inspiralling of mini black hole binaries. We here address our study in particular to the neutron stars, which could well become f-mode unstable producing therefore GWs. We estimate, for this particular source of GWs, the event rates that in principle can be detected by Schenberg and by the Dutch Mini-Grail antenna.Comment: 7 pages, 3 figures; Classical and Quantum Gravity (in press

Pseudoscorpiones (Arachnida) in phoretic association with Passalidae (Insecta, Coleoptera) in the Amazon State, Brazil

Pseudoscorpions were collected nocturnally at the upper Urubu River, Amazonas, Brazil, using artificial light, at monthly intervals between January 1982 and December 1983. 312 specimens of phoretic species, in three families, were collected from twelve species of passalid beetles. The pseudoscorpions collected were Tridenchthonius mexicanus CHAMB. & CHAMB., 1945 (Tridenchthoniidae) , Lustrochernes intermedius (BALZAN, 1891), Lustrochernes aff. reimoseri BEIER, 1932, and Americhernes aff. incertus MAHNERT, 1979 (Chernetidae), and Parawithius (Victorwithius) gracilimanus MAHNERT, 1979 (Withiidae). Observations on the phoretic behavior of each pseudoscorpion species, the frequency of individuals per carrier, their monthly occurrences, and the relative abundance of males, females and tritonymphs, the occurrence of females with brood sacs, and the frequency of each passalid beetle species with or without pseudoscorpions, are reported and discussed

Critical behavior at Mott-Anderson transition: a TMT-DMFT perspective

We present a detailed analysis of the critical behavior close to the Mott-Anderson transition. Our findings are based on a combination of numerical and analytical results obtained within the framework of Typical-Medium Theory (TMT-DMFT) - the simplest extension of dynamical mean field theory (DMFT) capable of incorporating Anderson localization effects. By making use of previous scaling studies of Anderson impurity models close to the metal-insulator transition, we solve this problem analytically and reveal the dependence of the critical behavior on the particle-hole symmetry. Our main result is that, for sufficiently strong disorder, the Mott-Anderson transition is characterized by a precisely defined two-fluid behavior, in which only a fraction of the electrons undergo a "site selective" Mott localization; the rest become Anderson-localized quasiparticles.Comment: 4+ pages, 4 figures, v2: minor changes, accepted for publication in Phys. Rev. Let

Choosing classrooms: a structured interview on children's right to participate

Discourses from distinct areas of knowledge converge on the relevance of listening to children's perspectives on their everyday lives and, specifically, in early childhood settings. Although children's participation is considered an important criterion to assess preschool settings’ quality, there is little empirical evidence on children's ideas in these settings. This study aims to develop and pilot a structured interview to assess children's conceptions, expectations, and perceptions about participation. Results suggest children consider they have more opportunities to make choices in the classroom characterized by the participation narrative. Furthermore, the participation classroom is consistently described as the one in which children would feel better, have more fun, and like the most, suggesting children value more classrooms in which participation occurs.info:eu-repo/semantics/acceptedVersio

Condition-specific mortality risk can explain differences in COVID-19 case fatality ratios around the globe

Objectives With COVID-19 infections resulting in death according to a hierarchy of risks, with age and pre-existing health conditions enhancing disease severity, the objective of this study is to estimate the condition-specific case fatality ratio (CFR) for different subpopulations in Italy. Study design The design of the study was to estimate the ‘pre-existing comorbidity’-conditional CFR to eventually explain the mortality risk variability reported around in different countries. Methods We use the available information on pre-existing health conditions identified for deceased patients ‘positive with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)’ in Italy. We (i) estimated the total number of deaths for different pre-existing health conditions categories and (ii) calculated a conditional CFR based upon the number of comorbidities before SARS-CoV-2 infection. Results Our results show a 0.6% conditional CFR for a population with zero pre-existing pathology, increasing to 13.9% for a population diagnosed with one and more pre-existing health conditions. Conclusions Condition-specific mortality risks are important to be evaluated during the COVID-19 pandemic, with potential elements to explain the CFR variability around the globe. A careful postmortem examination of deceased cases to differentiate death ‘caused by COVID-19’ from death ‘positive with SARS-CoV-2’ is therefore urgently needed and will likely improve our understanding of the COVID-19 mortality risk and virus pathogenicity.Marie Skłodowska-Curie grant agreement No 79249