On the distribution of an effective channel estimator for multi-cell massive MIMO

Accurate channel estimation is of utmost importance for massive MIMO systems to provide significant improvements in spectral and energy efficiency. In this work, we present a study on the distribution of a simple but yet effective and practical channel estimator for multi-cell massive MIMO systems suffering from pilot-contamination. The proposed channel estimator performs well under moderate to aggressive pilot contamination scenarios without previous knowledge of the inter-cell large-scale channel coefficients and noise power, asymptotically approximating the performance of the linear MMSE estimator as the number of antennas increases. We prove that the distribution of the proposed channel estimator can be accurately approximated by the circularly-symmetric complex normal distribution, when the number of antennas, M, deployed at the base station is greater than 10

Debugging mixed-signal circuits via the IEEE1149.4 Std. - analysis of limitations and requirements

Debugging mixed-signal circuits is traditionally seen as a complex task due to the presence of an analog part and the necessary interaction with a digital part. The use of debug tools that require physical access suffers from the same restrictions that led to the use of debug tools based on electronic access to digital circuits. While the IEEE1149.4 test infrastructure enables the structural and parametric test of mixed-signal boards, through electronic access, its use for debug purposes is still far from reaching a wide acceptance, namely due to the lack of a debug methodology. This work analyses several access mechanisms for Controllability, Observability and Verification operations via the IEEE1149.4 infrastructure, with an emphasis on the analysis of its limitations and requirements

Effectiveness of Surgery for Lumbar Spinal Stenosis : A Systematic Review and Meta-Analysis

Peer reviewedPublisher PD

A buil-in mixed-signal block observer (BIMBO) to improve observability in 1149.4 environments

This document proposes an extension to the IEEE 1149.4 test infrastructure, whereby a bank of sigma-delta first order modulators enables the simultaneous observation of several analog pins in a single component. The modulator output bit streams are shifted out and made available to an external test controller that comprises the corresponding bank of decimation filters and other decision and control logic. The architecture proposed is fully non-intrusive and may be used to support debug and test operations in mixed-signal environments

Novel experimental setup for time-of-flight mass spectrometry ion detection in collisions of anionic species with neutral gas-phase molecular targets

8 págs.; 4 figs.; Open Access funded by Creative Commons Atribution Licence 4.0We report a novel experimental setup for studying collision induced products resulting from the interaction of anionic beams with a neutral gas-phase molecular target. The precursor projectile was admitted into vacuum through a commercial pulsed valve, with the anionic beam produced in a hollow cathode discharge-induced plasma, and guided to the interaction region by a set of deflecting plates where it was made to interact with the target beam. Depending on the collision energy regime, negative and positive species can be formed in the collision region and ions were time-of-flight (TOF) mass-analysed. Here, we present data on O2 precursor projectile, where we show clear evidence of O– and O2 – formation from the hollow cathode source as well as preliminary results on the interaction of these anions with nitromethane, CH3NO2. The negative ions formed in such collisions were analysed using time-of-flight mass spectrometry. The five most dominant product anions were assigned to H–, O–, NO–, CNO– and CH3NO2 –.PLV acknowledges the Portuguese Foundation for Science and Technology (FCT-MEC) through SFRH/BSAB/105792/ 2014 during his sabbatical stay at CSIC, Madrid and the research grants PTDC/FIS-ATO/1832/2012 and UID/FIS/00068/ 2013. FFS acknowledges FCT-MEC through researcher grant IF-FCT IF/00380/2014. We also acknowledge the Spanish Ministerio de Economía y Competitividad (Project No. FIS 2012-31230). Some of this work forms part of the EU/ESF COST Actions CM1401 and CM1301, Our Astro-Chemical History and Chemistry for Electron-Induced Nanofabrication, respectively. LE-G and GG acknowledge the FP7-PEOPLE-2013-ITN research grant “Advanced Radiotherapy, Generated by Exploiting Nanoprocesses and Technologies (ARGENT)”.Peer Reviewe

Apresentação incomum de hepatite induzida por Epstein-Barr Virus em criança de 15 meses de idade

Objective: We report an atypical case of hepatitis in an infant that could be helpful to physicians of various specialties, as it demonstrates an atypical clinical and laboratorial manifestation of a disease not so common at that age and that could have gone undiagnosed. Case Description: A 15-month-old female, immunocompetent patient was referred to the hospital with a 3-day history of fever, vomiting, and diarrhea. The patient presented with alternation between sleepiness and irritation associated with rapid increase in serum liver enzymes levels, but no jaundice. Neurologic evaluation showed no meningeal signs and no encephalic morphological abnormalities were observed in a cranial CT scan. Treatment consisted of symptomatic medication and daily evaluation for signs of hepatic encephalopa- thy or bleeding. A serological panel showed negative IgM but positive IgG reactivity against Cytomega- lovirus (CMV) and IgM and IgG negative immunoreactivity against HAV. She was not tested for Hepatits B (HBV) or Hepatits C (HCV). Positive immunoreactivity against the Epstein-Barr virus capsid antigen (EBV VCA) IgM and negative reactivity against IgG, indicated a diagnosis of EBV-induced acute hepatitis. The patient was discharged asymptomatic after 11 days, with decreasing serum liver enzymes levels. A 15-day follow up evidenced complete remission of symptoms and normalized laboratory tests. Comments: Hepatic involvement in infections by Epstein-Barr Virus is common, presenting with moderate and transient increase in liver enzymes. It can go undetected and resolve spontaneously, while clinical manifestations of hepatitis are infrequent. In this report, we present an unusual case of a pediatric patient with hepatitis induced by EBV infection, along with a review of the literature. According to our search, no other EBV-induced hepatitis case reports have been published involving an immunocompetent patient under 2 years of ageObjetivo: Este relato de uma hepatite em um paciente pediátrico pode trazer benefícios para médicos de diversas especialidades, pois ele demonstra um quadro clínico e laboratorial atípicos de uma doença não tão comum nessa faixa etária e que poderia não ter sido diagnosticada. Descrição do Caso: Uma paciente, de 15 meses de idade, foi referenciada ao hospital com história de 3 dias de febre, vômitos e diarréia. A paciente apresentava alternância entre sonolência e irritação associada com rápida elevação das enzimas hepáticas, mas sem icterícia. Ao exame neurológico não foram evidenciados sinais meníngeos e a tomografia computadorizada de crânio não apresentou altera- ções. O tratamento consistiu em medicação sintomática junto à avaliação diária dos sinais de encefalopatia hepática ou sangramentos. O painel sorológico foi de IgM negativo e IgG positivo para Citomegalovirus (CMV) e IgM e IgG negativos para Anti-HAV. Em contraste, encontrou-se no soro IgM Imunorreativa contra o antígeno do capsídeo do vírus Epstein-Barr (EBV VCA), o que confirmou um diagnóstico de hepatite pelo EBV. A paciente recebeu alta hospitalar assintomática após 11 dias de internação, com declínio dos valores séricos das transaminases. Um acompanhamento após 15 dias da alta evidenciou completa remissão dos sintomas. Comentários: O envolvimento do fígado com infecções pelo vírus Epstein-Barr é comum, apresentando elevações moderadas e transitórias das enzimas hepáticas. Ela pode não ser detectada e ser autolimitada, enquanto manifestações hepáticas são infrequentes. Nesse relato de caso, é apresentado um quadro pediátrico atípico de um paciente que desenvolveu hepatite induzido pela infecção por EBV, além de uma revisão na literatura. De acordo com nossa busca, nenhum outro caso de hepatite induzida por EBV foi publicado envolvendo um paciente imunocompetente com idade inferior a 2 ano