Universal features of correlated bursty behaviour

Inhomogeneous temporal processes, like those appearing in human communications, neuron spike trains, and seismic signals, consist of high-activity bursty intervals alternating with long low-activity periods. In recent studies such bursty behavior has been characterized by a fat-tailed inter-event time distribution, while temporal correlations were measured by the autocorrelation function. However, these characteristic functions are not capable to fully characterize temporally correlated heterogenous behavior. Here we show that the distribution of the number of events in a bursty period serves as a good indicator of the dependencies, leading to the universal observation of power-law distribution in a broad class of phenomena. We find that the correlations in these quite different systems can be commonly interpreted by memory effects and described by a simple phenomenological model, which displays temporal behavior qualitatively similar to that in real systems

Rhodococcus equi venous catheter infection: a case report and review of the literature

<p>Abstract</p> <p>Introduction</p> <p><it>Rhodococcus equi </it>is an animal pathogen that was initially isolated from horses and is being increasingly reported as a cause of infection in humans with impaired cellular immunity. However, this pathogen is underestimated as a challenging antagonist and is frequently considered to be a mere contaminant despite the potential for life-threatening infections. Most case reports have occurred in immunocompromised patients who have received organ transplants (for example kidney, heart, bone marrow) or those with human immunodeficiency virus infection. Infections often manifest as pulmonary involvement or soft tissue abscesses. Bacteremia related to <it>R. equi </it>infections of tunneled central venous catheters has rarely been described.</p> <p>Case presentation</p> <p>We report the case of a 63-year-old non-transplant recipient, non-HIV infected Caucasian woman with endometrial carcinoma who developed recurrent bloodstream infections and septic shock due to <it>R. equi </it>and ultimately required the removal of her port catheter, a subcutaneous implantable central venous catheter. We also review the medical literature related to human infections with <it>R. equi</it>.</p> <p>Conclusion</p> <p><it>R. equi </it>should be considered a serious pathogen, not a contaminant, particularly in an immunocompromised patient who presents with a central venous catheter-related bloodstream infection. Counseling patients with central venous catheters who participate in activities involving exposure to domesticated animals is recommended.</p

Profile of Brazilian scientific production on A/H1N1 pandemic influenza

In the last few years, bibliometric studies have proliferated, seeking to provide data on world research. This study analyzes the profile of the Brazilian scientific production in the A (H1N1) influenza field between 2009 and 2011. The research was conducted in MEDLINE, SciELO and LILACS databases, selecting papers in which the term "H1N1" and "Brazil" were defined as the main topics. The data were analyzed taking into consideration the Brazilian state and institution in which the articles were produced, the impact factor of the journal and the language. The research revealed 40 documents (27 from MEDLINE, 16 from SciELO and 24 from LILACS). The journal impact factor ranged from 0.0977 to 8.1230. A similar amount of articles were written in English and Portuguese and São Paulo was the most productive state in the country, with 95% of the Brazilian production originating from the Southern and Southeastern regions. Linguistic data indicate that previous efforts made in order to improve the scientific production of Brazilian researchers making their observations attain a broader scientific audience produced results. It is necessary to assess the scientific studies, especially those conducted with public funds, in order to ensure that the results will benefit society.Nos últimos anos, estudos bibliométricos proliferaram, procurando prover dados sobre a pesquisa mundial. O presente estudo analisou o perfil da produção científica brasileira no campo da influenza A (H1N1) durante o período de 2009 a 2011. A pesquisa foi conduzida através das bases de dados Medline, SciELO e Lilacs, selecionando artigos onde os termos "H1N1" e "Brazil" foram definidos como tópicos principais. Os dados foram analisados considerando-se: o estado brasileiro e a institutição onde o trabalho foi produzido, o fator de impacto de periódico e a língua. A pesquisa revelou 40 documentos (27 provenientes do Medline, 16 do SciELO e 24 do Lilacs). O fator de impacto do periódico variou de 0.0977 a 8.1230. Uma quantidade similar de artigos foi escrita em inglês e em português. São Paulo foi o estado mais produtivo no país e 95% da produção eram provenientes das regiões Sul e Sudeste. Os dados linguísticos indicam que esforços anteriores para melhorar a produção científica dos pesquisadores brasileiros, fazendo com que suas observações atingissem um público científico mais amplo, foram alcançados. É necessário avaliar os estudos científicos, especialmente os realizados com fundos públicos, a fim de assegurar que os resultados beneficiem a sociedade

Reliability of Rapid Diagnostic Tests in Diagnosing Pregnancy-Associated Malaria in North-Eastern Tanzania.

Accurate diagnosis and prompt treatment of pregnancy-associated malaria (PAM) are key aspects in averting adverse pregnancy outcomes. Microscopy is the gold standard in malaria diagnosis, but it has limited detection and availability. When used appropriately, rapid diagnostic tests (RDTs) could be an ideal diagnostic complement to microscopy, due to their ease of use and adequate sensitivity in detecting even sub-microscopic infections. Polymerase chain reaction (PCR) is even more sensitive, but it is mainly used for research purposes. The accuracy and reliability of RDTs in diagnosing PAM was evaluated using microscopy and PCR. A cohort of pregnant women in north-eastern Tanzania was followed throughout pregnancy for detection of plasmodial infection using venous and placental blood samples evaluated by histidine rich protein 2 (HRP-2) and parasite lactate dehydrogenase (pLDH) based RDTs (Parascreen™) or HRP-2 only (Paracheck Pf® and ParaHIT®f), microscopy and nested Plasmodium species diagnostic PCR. From a cohort of 924 pregnant women who completed the follow up, complete RDT and microscopy data was available for 5,555 blood samples and of these 442 samples were analysed by PCR. Of the 5,555 blood samples, 49 ((proportion and 95% confidence interval) 0.9% [0.7 -1.1]) samples were positive by microscopy and 91 (1.6% [1.3-2.0]) by RDT. Forty-six (50.5% [40.5 - 60.6]) and 45 (49.5% [39.4 - 59.5]) of the RDT positive samples were positive and negative by microscopy, respectively, whereas nineteen (42.2% [29.0 - 56.7]) of the microscopy negative, but RDT positive, samples were positive by PCR. Three (0.05% [0.02 - 0.2]) samples were positive by microscopy but negative by RDT. 351 of the 5,461 samples negative by both RDT and microscopy were tested by PCR and found negative. There was no statistically significant difference between the performances of the different RDTs. Microscopy underestimated the real burden of malaria during pregnancy and RDTs performed better than microscopy in diagnosing PAM. In areas where intermittent preventive treatment during pregnancy may be abandoned due to low and decreasing malaria risk and instead replaced with active case management, screening with RDT is likely to identify most infections in pregnant women and out-performs microscopy as a diagnostic tool

CMB Telescopes and Optical Systems

The cosmic microwave background radiation (CMB) is now firmly established as a fundamental and essential probe of the geometry, constituents, and birth of the Universe. The CMB is a potent observable because it can be measured with precision and accuracy. Just as importantly, theoretical models of the Universe can predict the characteristics of the CMB to high accuracy, and those predictions can be directly compared to observations. There are multiple aspects associated with making a precise measurement. In this review, we focus on optical components for the instrumentation used to measure the CMB polarization and temperature anisotropy. We begin with an overview of general considerations for CMB observations and discuss common concepts used in the community. We next consider a variety of alternatives available for a designer of a CMB telescope. Our discussion is guided by the ground and balloon-based instruments that have been implemented over the years. In the same vein, we compare the arc-minute resolution Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT). CMB interferometers are presented briefly. We conclude with a comparison of the four CMB satellites, Relikt, COBE, WMAP, and Planck, to demonstrate a remarkable evolution in design, sensitivity, resolution, and complexity over the past thirty years.Comment: To appear in: Planets, Stars and Stellar Systems (PSSS), Volume 1: Telescopes and Instrumentatio