Rethinking State-Machine Replication for Parallelism

State-machine replication, a fundamental approach to designing fault-tolerant services, requires commands to be executed in the same order by all replicas. Moreover, command execution must be deterministic: each replica must produce the same output upon executing the same sequence of commands. These requirements usually result in single-threaded replicas, which hinders service performance. This paper introduces Parallel State-Machine Replication (P-SMR), a new approach to parallelism in state-machine replication. P-SMR scales better than previous proposals since no component plays a centralizing role in the execution of independent commands---those that can be executed concurrently, as defined by the service. The paper introduces P-SMR, describes a "commodified architecture" to implement it, and compares its performance to other proposals using a key-value store and a networked file system

Brownian Motion in Robertson-Walker Space-Times from electromagnetic Vacuum Fluctuations

We consider classical particles coupled to the quantized electromagnetic field in the background of a spatially flat Robertson-Walker universe. We find that these particles typically undergo Brownian motion and acquire a non-zero mean squared velocity which depends upon the scale factor of the universe. This Brownian motion can be interpreted as due to non-cancellation of anti-correlated vacuum fluctuations in the time dependent background space-time. We consider several types of coupling to the electromagnetic field, including particles with net electric charge, a magnetic dipole moment, and electric polarizability. We also investigate several different model scale factors.Comment: 29 pages, 7 figure

As representaçôes empregadas por cegos e surdos num ambiente virtual de aprendizagem

O objetivo deste artigo é discutir as representações utilizadas por aprendizes cegos e por aprendizes surdos envolvidos na resolução de problemas matemáticos. Motivados pela possibilidade de explora o potencial da Educação a Distância como modalidade educacional de inclusão para pessoas com necessidades educacionais especiais, em particular, para deficientes auditivos e visuais, utilizamos a ferramenta fórum de discussão do ambiente virtual de aprendizagem Moodle. Em nossas análises, identificamos aspectos que indicam alguma autonomia dos participantes, assim como o uso de representações visuais na tentativa de comunicar suas soluções

Comparison of vaginal wall sling and modified vaginal wall sling for stress urinary incontinence

CONTEXT: There are several controversies about which is the best form of surgical treatment for stress urinary incontinence in women. The vaginal wall sling in its original and modified form were presented by Raz as new options for treatment of these conditions, but there is a lack of comparative clinical trials using both techniques. OBJECTIVE: To compare the effectiveness of the original and the modified vaginal wall sling. DESIGN: A comparative, prospective, non-randomized clinical trial. SETTING: Public and private health care units (Urology Division, Faculty of Medicine of the ABC Foundation, and Universidade Federal de São Paulo (UNIFESP) / Escola Paulista de Medicina). PARTICIPANTS: Twenty patients with anatomical and intrinsic sphincter deficiency stress urinary incontinence were surgically treated for evaluating the initial results of the vaginal wall sling, from February 5, 1994, to June 27, 1996. INTERVENTIONS: The patients were divided into two groups. Group A (n = 10) were treated with the original vaginal wall sling. Group B (n = 10) were treated with the modified vaginal wall sling. Both groups were statistically similar according to clinical and urodynamic parameters. MAIN MEASUREMENTS: Cure and complication rates. RESULTS: Follow-up ranged from 19 to 43 months (median = 28) for group A. The overall cure rate was 70%. Fifty per cent of the patients had urinary retention of 7 to 35 days. There were no major complications. Follow-up ranged from 14 to 26 months (median = 18) for Group B. The cure rate was 80%. Two patients had urinary retention of 7 and 55 days. There were no major complications. CONCLUSIONS: The vaginal wall sling is as effective as the modified vaginal wall sling but has a higher rate of urinary retention.CONTEXTO: Existem diversas controvérsias sobre qual é a melhor forma de tratamento cirúrgico da incontinência urinária de esforço em mulheres. O sling de parede vaginal, em suas formas original e modificada, foi apresentado como nova opção no tratamento dessa condição, mas um estudo comparativo com ambas as técnicas ainda não foi publicado. OBJETIVO: Avaliar a eficácia dos slings de parede vaginal e modificado. DESENHO: Ensaio clínico comparativo, prospectivo, não randomizado. LOCAL: Serviços das Disciplinas de Urologia da Faculdade de Medicina do ABC e da Universidade Federal de São Paulo (UNIFESP). PARTICIPANTES: Vinte pacientes com incontinência urinária de esforço tipos anatômica e por deficiência esfincterina intrínseca foram tratadas cirurgicamente para avaliação dos resultados iniciais do sling de parede vaginal, de 05 de fevereiro de 1994 a 27 de junho de 1996. INTERVENÇÃO: As pacientes foram divididas em dois grupos. Grupo A (n = 10) tratadas com o sling de parede vaginal original. Grupo B (n = 10) tratadas com o sling modificado. Ambos os grupos foram estatisticamente similares de acordo com parâmetros clínicos e urodinâmicos. VARIÁVEIS ESTUDADAS: Índices de cura e de complicações. RESULTADOS: O seguimento variou de 19 a 43 meses (mediana = 28) para o grupo A. O índice geral de sucesso foi 70%. 50% das pacientes tiveram retenção urinária que durou de 7 a 35 dias. Não houve complicações maiores. O seguimento variou de 14 a 26 meses (mediana = 18) para o grupo B. O índice de sucesso foi 80%. Duas pacientes tiveram retenção urinária durante 7 e 55 dias. Não houve complicações maiores. CONCLUSÕES: O sling de parede vaginal modificado tem eficácia similar ao original, que, por sua vez, tem maior índice de retenção urinária.Faculty of Medicine of the ABC Foundation, São Paulo Urology DivisionUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Urology DivisionUNIFESP, EPM, Urology DivisionSciEL

Enhancement of declarative memory associated with emotional content in a Brazilian sample

ABSTRACTSeveral studies have documented that emotional arousal may enhance long-term memory. This is an adaptation of a paradigm previously used in North American and European samples in investigations of the influence of emotion on long-term retention. A sample of 46 healthy adults of high and low educational levels watched a slide presentation of stories. A randomly assigned group watched a story with an arousing content and another group watched a neutral story. The stories were matched for structure and comprehensibility and the set and order of the 11 slides were the same in both conditions. Immediately after viewing the slide presentation, the participants were asked to rate the emotionality of the narrative. The arousing narrative was rated as being more emotional than the neutral narrative (t (44) = -3.6, P<0.001). Ten days later subjects were asked to remember the story and answer a multiple-choice questionnaire about it. The subjects who watched the arousing story had higher scores in the free recall measure (t (44) = -2.59, P<0.01). There were no differences between groups in the multiple-choice test of recognition memory (t (44) = 0.26). These findings confirm that an emotional arousing content enhances longterm declarative memory and indicate the possibility of applying this instrument to clinical samples of various cultural backgrounds

Trends, Opportunities, and Challenges in Using Restricted Device Authentication in Fog Computing

The few resources available on devices restricted in Internet of Things are an important issue when we think about security. In this perspective, our work proposes a agile systematic review literature on works involving the Internet of Things, authentication, and Fog Computing. As a result, related works, opportunities, and challenges found at these areas' intersections were brought, supporting other researchers and developers who work in these areas

Lagrange and Markov spectra for typical smooth systems

We prove that among the set of smooth diffeomorphisms there exists a $C^1$-open and dense subset of data such that either the Lagrange spectrum is finite and the dynamics is a Morse-Smale diffeomorphism or the Lagrange spectrum has positive Hausdorff dimension and the system has positive topological entropy.Comment: 31 page

Effects of emotional reactivity on inhibitory avoidance in the elevated T-maze

ABSTRACTThe possibility of the presence of inter-individual emotional differences and the memory performance of rats was examined in the elevated T-maze. Two kinds of aversively motivated behaviors, inhibitory avoidance and escape learning, were measured. Based on the number of trials to achieve a learning criterion, rats were divided into two subgroups with either low or high avoidance reactivity (LAR or HAR, respectively). Retention test avoidance latencies showed that HAR animals had better avoidance memory (Mann-Whitney rank sum test, P = 0.0035). No such differences were found for the escape component of this test. These data suggest that individual emotional differences affect inhibitory avoidance performance, which may help to explain the dispersion of the data observed in other studies using this paradigm

Considerations about aging, memory and physical activity

A atividade física está relacionada a inúmeros benefícios físicos e mentais colaborando para a manutenção da saúde do cérebro, envolvendo mudanças na plasticidade sináptica e influenciando mecanismos de aprendizagem e memória. Após prática de atividade física tem sido observado um incremento na expressão do BDNF (fator neurotrófico derivado do cérebro), sendo este de fundamental importância para manter a sobrevivência e crescimento de muitos subtipos neuronais, surgindo como mediador-chave da eficiência sináptica. Apresentamos neste estudo, uma revisão sobre a influência do exercício físico sobre a memória dos idosos, enfatizando seus benefícios em contrapartida às perdas cognitivas decorrentes do envelhecimento. ________________________________________________________________________________ ABSTRACTPhysical activity is related to countless physical and mental benefits collaborating for the maintenance of the health of the brain, involving changes in the synaptic plasticity and influencing learning and memory mechanisms. After practicing physical activity an increment has been observed in the expression of BDNF (brain derived neurotrofic factor), this being of fundamental importance to maintain the survival and growth of many neurons subtypes, appearing as key-mediator of the synaptic efficiency. We present in this study, a revision of the influence of physical exercise on memory in old people, emphasizing their benefits in compensation to the current cognitive losses induced by aging