Generalized Metropolis dynamics with a generalized master equation: An approach for time-independent and time-dependent Monte Carlo simulations of generalized spin systems

The extension of Boltzmann-Gibbs thermostatistics, proposed by Tsallis, introduces an additional parameter $q$ to the inverse temperature $\beta$. Here, we show that a previously introduced generalized Metropolis dynamics to evolve spin models is not local and does not obey the detailed energy balance. In this dynamics, locality is only retrieved for $q=1$, which corresponds to the standard Metropolis algorithm. Non-locality implies in very time consuming computer calculations, since the energy of the whole system must be reevaluated, when a single spin is flipped. To circumvent this costly calculation, we propose a generalized master equation, which gives rise to a local generalized Metropolis dynamics that obeys the detailed energy balance. To compare the different critical values obtained with other generalized dynamics, we perform Monte Carlo simulations in equilibrium for Ising model. By using the short time non-equilibrium numerical simulations, we also calculate for this model: the critical temperature, the static and dynamical critical exponents as function of $q$. Even for $q\neq 1$, we show that suitable time evolving power laws can be found for each initial condition. Our numerical experiments corroborate the literature results, when we use non-local dynamics, showing that short time parameter determination works also in this case. However, the dynamics governed by the new master equation leads to different results for critical temperatures and also the critical exponents affecting universality classes. We further propose a simple algorithm to optimize modeling the time evolution with a power law considering in a log-log plot two successive refinements.Comment: 10 pages, 5 figures and 5 table

Optical mouse acting as biospeckle sensor

In this work we propose some experiments with the use of optical computer mouse, associated to low cost lasers that can be used to perform several measurements with applications in industry and in human health monitoring. The mouse was used to grab the movements produced by speckle pattern changes and to get information through the adaptation of its structure. We measured displacements in wood samples under strain, variations of the diameter of an artery due to heart beat and, through a hardware simulation, the movement of an eye, an experiment that could be of low cost help for communication to severely handicapped motor patients. Those measurements were done in spite of the fact that the CCD sensor of the mice is monolithically included into an integrated circuit so that the raw image cannot be accessed. If, as was the case with primitive optical mouse, that signal could be accessed, the quality and usefulness of the measurements could be significantly increased. As it was not possible, a webcam sensor was used for measuring the drying of paint, a standard phenomenon for testing biospeckle techniques, in order to prove the usefulness of the mouse design. The results showed that the use of the mouse associated to a laser pointer could be the way to get metrological information from many phenomena involving the whole field spatial displacement, as well as the use of the mouse as in its prime version allowed to get images of the speckle patterns and to analyze them.Centro de Investigaciones Óptica

Universality in Bibliometrics

Many discussions have enlarged the literature in Bibliometrics since the Hirsh proposal, the so called $h$-index. Ranking papers according to their citations, this index quantifies a researcher only by its greatest possible number of papers that are cited at least $h$ times. A closed formula for $h$-index distribution that can be applied for distinct databases is not yet known. In fact, to obtain such distribution, the knowledge of citation distribution of the authors and its specificities are required. Instead of dealing with researchers randomly chosen, here we address different groups based on distinct databases. The first group is composed by physicists and biologists, with data extracted from Institute of Scientific Information (ISI). The second group composed by computer scientists, which data were extracted from Google-Scholar system. In this paper, we obtain a general formula for the $h$-index probability density function (pdf) for groups of authors by using generalized exponentials in the context of escort probability. Our analysis includes the use of several statistical methods to estimate the necessary parameters. Also an exhaustive comparison among the possible candidate distributions are used to describe the way the citations are distributed among authors. The $h$-index pdf should be used to classify groups of researchers from a quantitative point of view, which is meaningfully interesting to eliminate obscure qualitative methods.Comment: To appear in Physica A (8 pages, 6 figures and 2 tables

Synthesis of carbon nanostructures by chemical vapour deposition over Ni-Al co-oxides using plastic solid waste as precursor

Europe contributed with 18.5% of the almost 3!50 Mton of plastics produced worldwide in 2017. Polypropylene (PP) and light and heavy density polyethylene (LOPE and HOPE, respectively) represents near 49.1% of the plastics produced in Europe. Packaging is the main application of these plastics, so typically they have one-single use. In 2014, 25.8 Mton of post-consumer plastic solid wastes (PSWs) ended up in the official waste streams (54.0% of the demanded quantity), 69.2% being recovered through recycling (7.7 Mton) and enen~y recovery processes (10.2 Mton), the remaining 30.8% sent to landfill [1]. Concerns about usage and disposal are diverse and include accumulation of PSWs in landfills and in natural habitats, physic;al problems for wildlife resulting from ingestion or entanglement in plastic and the leaching of chemicals from plastic products [2]. The incineration of PSWs contributes to pollution due to harmful and tC»xic emissions and both incineration and mechanical recycling are costly and may or may not be economically viable in different situations [3]. More attractive strategies are the production of carbon nanomate!rials using PSWs as carbon precursors [4]. In this work, Ni-AI eo-oxide nanoparticles were synthesiz,ed by eo-precipitation and employed as catalysts in the chemical vapour deposition of CNTs when using LOPE as carbon precursor and as model compound of plastic solid waste. Fig. 1 shows the scanning electron micrographs of the carbon nanostructures prepared at 1000 °C during 1 h in a tubular furnace under 10 NmL·min·1 nitrogen flow. As can be observed, CNTs and carbon nanospheres were produced.This work is a result of Project "PLASTIC_TO_FUEL&IMATs - Upcycling Waste Plastics into Fuel and Carbon Nanomaterials", with the reference POCI-01-0145-FEDER-031439, through the Competitiveness and Internationalization Operational Program. supported by the European Regional Development Fund (ERDF); the Associate Laboratory LSRE-LCM- UID/EQU/50020/2019 - funded by national funds through FCT/MCTES (PIDDAC); and CIMO UID/AGR/00690/2019 through FEDER under Program PT2020.info:eu-repo/semantics/publishedVersio

Controle de qualidade de marcações de PSMA-11, utilizando um gerador itinerante de Ge68- Ga68 para estudos de PET-CT

Introdução: Este estudo trata do controle de qualidade do radiofármaco utilizado em estudos de PET-CT para diagnóstico e/ou estadiamento de pacientes acometidos pelo câncer de próstata. Objetivo: Avaliar a qualidade do radiofármaco PSMA-11, marcado com uso de gerador de Ge68-Ga68 itinerante. Método: Análise do aspecto visual, pH e pureza radioquímica do radiofármaco marcado a cada recebimento do gerador de Ge68-Ga68. Resultado: Todas as marcações realizadas se apresentaram límpidas quanto ao aspecto visual, o pH ficou entre 5,0 e 6,0 e a pureza radioquímica apresentou em 92% dos casos valores ³ 96%. Conclusão: Com os devidos controles de qualidade, pode ser uma opção para uso na clínica médica, em serviços que não disponham de condição para adquirir um sistema, por ser importado

Experimental and Numerical Investigation of Post-Flutter Limit Cycle Oscillations on a Cantilevered Flat Plate

Futuristic aircraft designs and novel aircraft such as High Altitude Long Endurance (HALE) involve a higher level of structural flexibility than in conventional aircraft. Even at present, the trends in the aviation industry are to increase wing length (to reduce induced drag) and maxi- mize use of composites, which lead to increased structural flexibility. This necessitates a rethink of conventional (linear) aeroelastic analysis, since the increased flexibility results in coupling between the flight dynamic and aeroelastic dynamics, and consequently, limit-cycle oscillations of the structure. In this paper, a new three-dimensional low-order model for unsteady aerody- namics that accounts for large oscillation amplitudes and nonplanar wakes is developed. An experiment with a cantilevered flat plate at low Reynolds number is set up and used to validate the low-order model, as well as to study post-flutter limit-cycle oscillations. Results from the low-order model are promising, but show that aerodynamic nonlinearities such as flow sepa- ration and leading-edge vortex shedding must also be modeled in order to predict all possible limit-cycle oscillations of the aeroelastic system

Implantes de diâmetro reduzido, considerações sobre a liga roxolid

Os implantes dentários de titânio de diâmetro estreito podem ajudar a superar algumas limitações verificadas na instalação de implantes de diâmetro normal, como nos casos de pouca largura do rebordo ou pouco espaço interdentário. Entretanto, com o avanço nos desenhos dos implantes, nas conexões protéticas e nas ligas de titânio possibilitam melhores resultados no uso de implantes com diâmetro reduzido em regiões posteriores de maxila e mandíbula com maior frequência, garantindo um alto índice de sucesso. Diversos motivos que impossibilitem ou contraindiquem o uso de implantes de maior diâmetro em áreas de molares, o uso de implantes de diâmetro reduzido tem sido uma grande alternativa para estes casos. Nesse contexto, destaca-se a liga Roxolid®, a qual é composta pelos elementos titânio e zircónio. Assim sendo, o presente estudo visa abordar o uso de implantes de diâmetro reduzido (Ø 3,3mm) do tipo Roxolid®, inseridos em áreas onde a espessura óssea impossibilita o uso de implantes de diâmetro convencional

Association between muscle strength and the\ud cardiopulmonary status of individuals living with\ud HIV/AIDS

OBJECTIVE: The purpose of this study was to compare aerobic function [anaerobic threshold (%_VVO2-AT),\ud respiratory compensation point (%_VVO2-RCP) and peak oxygen uptake (_VVO2peak)] between physically active patients\ud with HIV/AIDS and matched controls and to examine associations between disease status, poor muscle strength,\ud depression (as estimated by the profile of mood states questionnaire) and the aerobic performance of patients.\ud METHODS: Progressive treadmill test data for %_VVO2-AT (V-slope method), RCP and (_VVO2peak) were compared\ud between 39 male patients with HIV/AIDS (age 40.6¡1.4 years) and 28 male controls (age 44.4¡2.1 years) drawn\ud from the same community and matched for habitual physical activity. Within-patient data were also examined in\ud relation to CD4+ counts (nadir and current data) and peak isokinetic knee torque.\ud RESULTS: AT, RCP and (_VVO2peak) values were generally similar for patients and controls.Within the patient sample,\ud binary classification suggested that AT, RCP and (_VVO2peak) values were not associated with either the nadir or\ud current CD4+ count, but treadmill test variables were positively associated with peak isokinetic knee torque.\ud CONCLUSION: The aerobic performance of physically active patients with HIV/AIDS is generally well conserved.\ud Nevertheless, poor muscle strength is observed in some HIV/AIDS patients, which is associated with lower anaerobic\ud power and (_VVO2peak), suggesting the possibility of enhancing the aerobic performance of patients with weak\ud muscles through appropriate muscle-strengthening activities