Energy efficiency of mmWave massive MIMO precoding with low-resolution DACs

With the congestion of the sub-6 GHz spectrum, the interest in massive multiple-input multiple-output (MIMO) systems operating on millimeter wave spectrum grows. In order to reduce the power consumption of such massive MIMO systems, hybrid analog/digital transceivers and application of low-resolution digital-to-analog/analog-to-digital converters have been recently proposed. In this work, we investigate the energy efficiency of quantized hybrid transmitters equipped with a fully/partially-connected phase-shifting network composed of active/passive phase-shifters and compare it to that of quantized digital precoders. We introduce a quantized single-user MIMO system model based on an additive quantization noise approximation considering realistic power consumption and loss models to evaluate the spectral and energy efficiencies of the transmit precoding methods. Simulation results show that partially-connected hybrid precoders can be more energy-efficient compared to digital precoders, while fully-connected hybrid precoders exhibit poor energy efficiency in general. Also, the topology of phase-shifting components offers an energy-spectral efficiency trade-off: active phase-shifters provide higher data rates, while passive phase-shifters maintain better energy efficiency.Comment: Published in IEEE Journal of Selected Topics in Signal Processin

Constitutive parameter identification based on non-homogeneous uniaxial compression tests of PLGA

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2019.Materiais poliméricos bioabsorvíveis possuem propriedades físico-químicas atrativas para serem empregados em aplicações médicas. Desta forma, a proposição de modelos constitutivos capazes de reproduzir o comportamento mecânico desses materiais, bem como a caracterização de propriedades e parâmetros constitutivos tornam-se essenciais no projeto de componentes mecânicos e implantes seguros. A identificação de parâmetros constitutivos, por sua vez, permite compatibilizar resultados de ensaios laboratoriais e modelos computacionais à realidade observada nas mais diversas condições de aplicação de um produto. Em geral, testes são projetados para que propriedades intrínsecas do material sejam facilmente extraídas, idealmente sem dependência da geometria do corpo de prova, contudo isso nem sempre é viável. Por exemplo, sob condições usuais, testes de compressão do polímero bioabsorvível PLGA 85:15 apresentam instabilidades que tornam o processo caracterização irreprodutíveis. Uma alternativa para se obter resultados consistentes desse material sobre compressão é através da realização de testes de compressão não homogêneos, com a presença de barrilamento. Isso, porém, impacta no processo de identificação de parâmetros, elevando significativamente a complexidade de ferramentas computacionais necessárias e o tempo necessário para o processo. Dentro desse contexto, este trabalho apresenta procedimentos para identificação de parâmetros constitutivos considerando ensaios de compressão não-homogêneos do material PLGA 85:15. Esse trabalho se propõe a analisar os procedimentos, visando uma identificação mais eficiente, e apresentar os parâmetros identificados. São considerados quatro procedimentos de identificação baseados em otimização. Os procedimentos fazem uso de algoritmos de otimização heurísticos (Particle Swarm - Nelder-Mead optimization) com hibridização global-local. Em cada procedimento é variado o grau de fidelidade ao experimento, considerando desde simulações numéricas de alta fidelidade utilizando o método de elementos finitos até simulações simplificadas, sem barrilamento, porém de computo mais rápido. Dois modelos constitutivos desenvolvidos anteriormente pelo grupo foram empregados, sendo esses modelos adequados a representação do comportamento elasto-viscoplástico e viscoelástico de materiais poliméricos. Uma análise comparativa entre as propostas é realizada em termos de adequação aos resultados experimentais e ao tempo requerido para realização do procedimento de identificação. Os modelos constitutivos foram capazes de representar o comportamento do material com sucesso. Todos os procedimentos realizados apresentaram respostas semelhantes, porém não idênticas e é observada uma diferença significativa entre procedimentos no tempo requerido para executá-los. Desta forma, o presente trabalho apresenta vantagens e desvantagens de cada método, auxiliando na escolha entre procedimentos.Abstract: Bioresorbable polymer materials have attractive physicochemical properties, suitable for medical applications. In order to aid in the design process of safe mechanical components, it becomes necessary to characterize these materials and propose sophisticated constitutive models, capable of reproducing the material?s mechanical behavior. The identification of constitutive parameters allows to compatibilize laboratory test results and computational models to the reality observed under the most diverse conditions of application of a product. In general, tests are designed so that intrinsic properties of the materials are easily extracted, ideally without dependence on the geometry of the test specimen, however this is not always feasible. For example, under usual conditions, compressive tests of the bioabsorbable polymer PLGA 85:15 exhibit instabilities that make the test results irreproducible. An alternative to obtain consistent results of this material upon compression is through non-homogeneous compression tests, with the presence of barrelling. This, however, impacts on the parameter identification process by significantly increasing the complexity of the computational tools needed and the time required for the process. Considering this context, this work presents procedures for identification of constitutive parameters considering non-homogeneous compression tests of PLGA 85:15. This work proposes to analyze identification procedures, aiming at a more efficient identification, and to present the identified parameters. Four identification procedures based on optimization are considered. The procedures make use of heuristic optimization algorithms (Particle Swarm - Nelder-Mead optimization) with global-local hybridization. In each procedure the degree of fidelity to the experiment is varied, considering from high fidelity numerical simulations, using the finite element method, to simplified simulations, but with faster computation time. Two constitutive models previously developed by the group were employed, these models are considered adequate to represent the elasto-viscoplastic and viscoelastic behavior of polymeric materials. A comparative analysis between proposals is carried out in terms of adequacy to the experimental results and to the time required to carry out the identification procedure. The constitutive models were able to represent the behavior of the material successfully. All procedures presented similar but non-identical responses and a significant difference in time required to execute the procedure is observed between them. In this way, the present work presents advantages and disadvantages of each method, aiding in the choice between procedures

Effect of Pions in Cosmic Rays

The effects of pions for vacuum polarization in background magnetic fields are considered. The effects of quark condensates is also briefly addresses. Although these effects are out of the measurement accuracy of laboratory experiments they may be relevant for gamma-ray burst propagation. In particular, for emissions from the center of the galaxy, we show that the mixing between the neutral pion and photons results in a deviation of the gamma-ray spectrum from the standard power-law in the TeV range.Comment: 6 pages, 3 figures; Based in arXiv:0707.4200 with a new very short discussion in qq condensates. To appear in the Proceedings of Scadron'7

A global anomaly from the Z-string

The response of isodoublet fermions to classical backgrounds of essentially 2-dimensional boson fields in SU(2) Yang-Mills-Higgs theory is investigated. In particular, the spectral flow of Dirac eigenvalues is calculated for a non-contractible sphere of configurations passing through the vacuum and the Z-string (the embedded vortex solution). Also, a non-vanishing Berry phase is established for adiabatic transport "around" the Z-string. These results imply the existence of a new type of global (non-perturbative) gauge anomaly in SU(2) Yang-Mills-Higgs quantum field theory with a single doublet of left-handed fermions. Possible extensions to other chiral gauge field theories are also discussed.Comment: In Section 6 error corrected for SU(2) theories with general isospin; conclusions changed significantl

Characterization of patient falls according to the notification in adverse event reports

Este estudo foi desenvolvido com o objetivo de caracterizar as quedas de pacientes internados ocorridas em hospital terciário. Foram analisados 826 Boletins de Notificação de Eventos Adversos, de um período de 30 meses, que registraram 0,30 quedas por 1000 pacientes/dia. Quedas do leito foram mais frequentes (55%), com maior prevalência na enfermaria de neurologia. Maior frequência de quedas foi verificada no período noturno (63,7%), nos primeiros cinco dias da admissão (61,7%), nos pacientes de sexo masculino (57,5%) e na faixa etária maior de 60 anos (50%). Nos casos de quedas do leito, os diagnósticos relacionaram-se a doenças infecciosas e parasitárias (18,2%), doenças do sistema nervoso (18,2%) e doenças do aparelho circulatório (13,7%). Nas quedas da própria altura, os diagnósticos relacionaram-se a neoplasias (19,4%) e doenças do aparelho geniturinário (16,1%). A caracterização desses eventos adversos auxilia no reconhecimento dos grupos de maior risco e na elaboração de propostas preventivas.Esta investigación fue desarrollada con el objetivo de verificar las características de las caídas sufridas por pacientes internados en un hospital privado. Fueron analizados 826 Boletines de Notificación de Eventos Adversos, en un período de 30 meses. Fueron registradas 0,30 caídas por cada 1000 pacientes/día. Las caídas de la cama fueron las más frecuentes (55%), con mayor prevalencia en la Enfermería de Neurología. Se verificó una mayor frecuencia de caídas en el período nocturno (63,7%), durante los primeros cinco días de admisión (61,7%), en los pacientes de sexo masculino (57,5%) y en la faja etaria de mayores de 60 años (50%). En los casos de caídas de la cama, los diagnósticos se relacionaban con enfermedades infecciosas y parasitarias (18,2%), enfermedades del sistema nervioso (18,2%) y enfermedades del aparato circulatorio (13,7%). En las caídas directas del cuerpo, se encontró relación con las neoplasias (19,4%) y enfermedades del aparato genitourinario (16,1%). La caracterización de esos eventos adversos coadyuva en el reconocimiento de los grupos de mayor riesgo y en la elaboración de propuestas de carácter preventivo.The objective of this study was to observe the characteristics of falls occurring in the inpatient population at a tertiary hospital. Eight hundred and twenty-six Adverse Events Notification Reports were analyzed over a 30 months period, and 0.30 falls per 1,000 patients/day were reported. Falls from beds were the most frequent (55%), showing the highest occurrence in the neurology ward. A higher frequency of falls was observed at night time (63.7%), during the first five hospitalization days (61.7%), in male patients (57.5%) over 60 years old (50%). In cases of falls from a bed, the diagnoses were related to infectious and parasitic diseases (18.2%), diseases affecting the nervous system (18.2%) and those affecting the circulatory system (13.7%). In cases of falls from one's own height, they were related to neoplasms (19.4%) and diseases affecting the genitourinary system (16.1%). It is concluded that high importance should be placed on studying the population to characterize those at high risk for falls to assist in the implementation of preventive measures

High dillution of Staphysagria and fruit fly biotherapic preparations to manage South American fruit fly, Anastrepha fraterculus, in organic peach orchards.

The peach, Prunus persica, is an important economic crop in southern Brazil, where family farms are predominantly small. The South American fruit fly, Anastrepha fraterculus is a limiting factor to increased production in orchard crops. Increased organic production in Brazil has stimulated research to find ecological based pest management. This research was carried out in order to evaluate the efficacy of preparations at high dilution in managing A. fraterculus in organic peach orchards. Experiments were conducted under field conditions in randomized blocks during 2003/04 and 2004/05. Treatments consisted of A. fraterculus nosodes and Staphysagria homeopathic preparations, both at two high dilution levels, 3CH and 6CH (centesimal hahnemannian dilution method), applied at two spray intervals, 5 and 10 days, and a control. Fruit losses due to A. fraterculus infestation varied from 40 to 98.3%. Although there were significant differences among treatments in the first harvest of two of the three experiments there were no significant differences in the second harvest of any of the experiments. None of the homeopathic preparations reduced the incidence of infested fruit significantly below that of the water control in any of the three experiments. Further studies must combine other strategies such as bagging fruits and planting of early season cultivars. Variation on high dilution potency, dose, and frequency of application must also be considered

Efeito do estilo de vida e comorbidades nas internações por doenças do aparelho circulatório

RESUMO Objetivo: determinar a relação entre o estilo de vida, presença de hipertensão, diabe-tes e dislipidemia com a taxa de internação hospitalar (IH) por doenças do aparelho circulatório (DC) nos estados brasileiros. Método: foi realizado um estudo de caráter ecológico utilizando a base de dados DATASUS referente ao estilo de vida e comorbi-dades nos estados brasileiros. Os dados foram analisados por meio de regressão linear bivariada e multivariada, tendo como desfecho a IH por DC. Resultados: a prevalência de IH média mensal no Brasil foi de 43,9/100.000 habitantes, com maior índice no Pa-raná com 67,4/100.000 habitantes enquanto a menor foi no Amazonas, apresentando 17,6/100.000 habitantes. Na análise por correlação bivariada com à IH por DC foram os observados os seguintes valores: % Insuficientemente ativos (r=0,224, p=0,252), % Con-sumo regular doces (r=0,671; p<0,001), % Fumantes atuais (r=0,395; p=0,038), % Consu-mo elevado de sal (r=0,323; p=0,094), % Diagnóstico HAS (r=0,662; p<0,001), % Diagnós-tico de DM (DM) (r=0,453; p=0,016), % Diagnóstico de Dislipidemia (r=0,398; p=0,036). Conclusão: deve-se atentar para o fato de que o estilo de vida e a presença de comor-bidades afeta diretamente a evolução para IH por DC, sendo importante a mudança dos mesmos para evitar a ocorrência deste desfecho. ABSTRACT Objective: to determine the relationship between lifestyle, presence of high blood pressure, diabetes and dyslipidemia with hospital admission rate (HA) due to diseases of the circulatory system (CD) in brazilian states. Method: an ecological study was con-ducted using the DATASUS database on lifestyle and comorbidities in the brazilian sta-tes. The data were analyzed by bivariate and multivariate linear regression, with HA by CD Results: the prevalence of monthly HA in Brazil was 43.9/100,000 inhabitants, with a higher index in Paraná with 67.4/100,000 inhabitants while the lowest was in Amazo-nas, presenting 17.6/100,000 inhabitants. In the analysis by bivariate correlation with HA by CD, the following values were observed% insufficiently active (r = 0.224, p = 0.252), % sweet regular consumption (r = 0.671, p <0.001), Current smokers (r = 0.395, p = 0.038), % High salt intake (r = 0.333, p = 0.094), % Diagnosis of Arterial Hypertension (r = 0.662, p <0.001), % Diagnosis of Diabetes Mellitus (DM) (r = 0.453, p = 0.016), % Di-agnosis of Dyslipidemia (r = 0.398, p = 0.036). Conclusion: therefore, attention should be paid to the fact that lifestyle and the presence of comorbidities directly affect the evolution to HA by CD, and it is important to change them to avoid the occurrence of this outcome

Yang-Lee zeros for a nonequilibrium phase transition

Equilibrium systems which exhibit a phase transition can be studied by investigating the complex zeros of the partition function. This method, pioneered by Yang and Lee, has been widely used in equilibrium statistical physics. We show that an analogous treatment is possible for a nonequilibrium phase transition into an absorbing state. By investigating the complex zeros of the survival probability of directed percolation processes we demonstrate that the zeros provide information about universal properties. Moreover we identify certain non-trivial points where the survival probability for bond percolation can be computed exactly.Comment: LaTeX, IOP-style, 13 pages, 10 eps figure

Identifying the quark content of the isoscalar scalar mesons f_0(980), f_0(1370), and f_0(1500) from weak and electromagnetic processes

The assignments of the isoscalar scalar mesons f0(980), f0(1370), and f0(1500) in terms of their qqbar substructure is still a matter of heated dispute. Here we employ the weak and electromagnetic decays D(s)(+) to f0+pi(+) and f0 two-photon decays, respectively, to identify the f0(980) and f0(1500) as mostly ssbar, and the f0(1370) as dominantly nonstrange, in agreement with previous work. The two-photon decays can be satisfactorily described with quark as well as with meson loops, though the latter ones provide a less model-dependent and more quantitative description.Comment: v1, 15 pages, plain LaTeX, 1 eps figure. v2, 18 pages, plain LaTeX (figure included). More discussion, especially on the f0(1370) and its empirical two-photon widt