c-axis transport and phenomenology of the pseudo-gap state in Bi2Sr2CaCu2O8+δBi_2Sr_2CaCu_2O_{8+\delta}

We measure and analyze the resistivity of $Bi_2Sr_2CaCu_2O_{8+\delta}$ crystals for different doping $\delta$. We obtain the fraction of carrier $\eta(T,\delta) = n_g/n_{TOT}$ that do not participate to the c-axis conductivity. All the curves $\eta(T,\delta)$ collapse onto a universal curve when plotted against a reduced temperature $x=[T-\Theta(\delta)]/\Delta^{*}(\delta)$. We find that at the superconducting transition $n_g$ is doping independent. We also show that a magnetic field up to 14 T does not affect the degree of localization in the (a,b) planes but widens the temperature range of the x-scaling by suppressing the superconducting phase coherence.Comment: 11 pages, 5 figures, submitted to Phys.Rev.

Estimating Self-Sustainability in Peer-to-Peer Swarming Systems

Peer-to-peer swarming is one of the \emph{de facto} solutions for distributed content dissemination in today's Internet. By leveraging resources provided by clients, swarming systems reduce the load on and costs to publishers. However, there is a limit to how much cost savings can be gained from swarming; for example, for unpopular content peers will always depend on the publisher in order to complete their downloads. In this paper, we investigate this dependence. For this purpose, we propose a new metric, namely \emph{swarm self-sustainability}. A swarm is referred to as self-sustaining if all its blocks are collectively held by peers; the self-sustainability of a swarm is the fraction of time in which the swarm is self-sustaining. We pose the following question: how does the self-sustainability of a swarm vary as a function of content popularity, the service capacity of the users, and the size of the file? We present a model to answer the posed question. We then propose efficient solution methods to compute self-sustainability. The accuracy of our estimates is validated against simulation. Finally, we also provide closed-form expressions for the fraction of time that a given number of blocks is collectively held by peers.Comment: 27 pages, 5 figure

Size-Dependent Deposition, Translocation, and Microglial Activation of Inhaled Silver Nanoparticles in the Rodent Nose and Brain.

BackgroundSilver nanoparticles (AgNP) are present in personal, commercial, and industrial products, which are often aerosolized. Current understanding of the deposition, translocation, and health-related impacts of AgNP inhalation is limited.ObjectivesWe determined a) the deposition and retention of inhaled Ag in the nasal cavity from nose-only exposure; b) the timing for Ag translocation to and retention/clearance in the olfactory bulb (OB); and c) whether the presence of Ag in the OB affects microglial activity.MethodsMale Sprague-Dawley rats were exposed nose-only to citrate-buffered 20- or 110-nm AgNP (C20 or C110, respectively) or citrate buffer alone for 6 hr. The nasal cavity and OB were examined for the presence of Ag and for biological responses up to 56 days post-exposure (8 weeks).ResultsThe highest nasal Ag deposition was observed on Day 0 for both AgNP sizes. Inhalation of aerosolized C20 resulted in rapid translocation of Ag to the OB and in microglial activation at Days 0, 1, and 7. In contrast, inhalation of C110 resulted in a gradual but progressive transport of Ag to and retention in the OB, with a trend for microglial activation to variably be above control.ConclusionsThe results of this study show that after rats experienced a 6-hr inhalation exposure to 20- and 110-nm AgNP at a single point in time, Ag deposition in the nose, the rate of translocation to the brain, and subsequent microglial activation in the OB differed depending on AgNP size and time since exposure. Citation: Patchin ES, Anderson DS, Silva RM, Uyeminami DL, Scott GM, Guo T, Van Winkle LS, Pinkerton KE. 2016. Size-dependent deposition, translocation, and microglial activation of inhaled silver nanoparticles in the rodent nose and brain. Environ Health Perspect 124:1870-1875; http://dx.doi.org/10.1289/EHP234

Short versus long silver nanowires: a comparison of in vivo pulmonary effects post instillation.

BackgroundSilver nanowires (Ag NWs) are increasingly being used to produce touchscreens for smart phones and computers. When applied in a thin film over a plastic substrate, Ag NWs create a transparent, highly-conductive network of fibers enabling the touch interface between consumers and their electronics. Large-scale application methods utilize techniques whereby Ag NW suspensions are deposited onto substrates via droplets. Aerosolized droplets increase risk of occupational Ag NW exposure. Currently, there are few published studies on Ag NW exposure-related health effects. Concerns have risen about the potential for greater toxicity from exposure to high-aspect ratio nanomaterials compared to their non-fibrous counterparts. This study examines whether Ag NWs of varying lengths affect biological responses and silver distribution within the lungs at different time-points.MethodsTwo different sizes of Ag NWs (2 μm [S-Ag NWs] and 20 μm [L-Ag NWs]) were tested. Male, Sprague-Dawley rats were intratracheally instilled with Ag NWs (0, 0.1, 0.5, or 1.0 mg/kg). Broncho-alveolar lavage fluid (BALF) and lung tissues were obtained at 1, 7, and 21 days post exposure for analysis of BAL total cells, cell differentials, and total protein as well as tissue pathology and silver distribution.Results and conclusionsThe two highest doses produced significant increases in BAL endpoints. At Day 1, Ag NWs increased total cells, inflammatory polymorphonuclear cells (PMNs), and total protein. PMNs persisted for both Ag NW types at Day 7, though not significantly so, and by Day 21, PMNs appeared in line with sham control values. Striking histopathological features associated with Ag NWs included 1) a strong influx of eosinophils at Days 1 and 7; and 2) formation of Langhans and foreign body giant cells at Days 7 and 21. Epithelial sloughing in the terminal bronchioles (TB) and cellular exudate in alveolar regions were also common. By Day 21, Ag NWs were primarily enclosed in granulomas or surrounded by numerous macrophages in the TB-alveolar duct junction. These findings suggest short and long Ag NWs produce pulmonary toxicity; thus, further research into exposure-related health effects and possible exposure scenarios are necessary to ensure human safety as Ag NW demand increases

Implementation of the Improved Access and Quality Program according to Primary Care managers in Sao Paulo

Objective: To analyze the implementation of the National Improved Access and Quality Program according to Primary Health Care managers. Methods: The thematic oral history was used, through semistructured interviews with five managers from Primary Health Care Services who participated actively in the two cycles of the Program in an administrative district of Sao Paulo City. The subjects answered the question "How do you assess the implementation process of the National Improved Access and Quality Program at this Primary Health Care Service?", among others. The analysis of the testimonies revealed the categories "The managers' perception of the implementation of the National Improved Access and Quality Program" and "Changes in the work processes since the implementation of the National Improved Access and Quality Program". Results: The managers acknowledged the Program as a well-structured proposal, which permits a broader management view on the health services. The interviewees evidenced the use of the quality indicators, which was hardly addressed and understood in the managers and teams' daily reality though. The interviewees demonstrated that they do not understand the concepts of continuing education and institutional support. The external evaluation phase was considered subjective and without standardization, producing data that did not contribute to the assessment of the changes the teams made. Conclusion: The systematic incorporation process of the assessment culture to support the continuing quality improvement in Primary Health Care is incipient. Despite the continuing distance between the proposals of Primary Health Care and the practice at the Primary Health Care services studied, the Program favored the organization of the work processes and contributed to the managers' focus on the teams' practice and their own activities.Objetivo: Analisar a implementação do Programa Nacional de Melhoria do Acesso e da Qualidade segundo gerentes de Unidades Básicas de Saúde. Métodos: Utilizou-se a história oral temática, por meio de entrevistas semiestruturadas com cinco gerentes de Unidades Básicas de Saúde que participaram ativamente dos dois ciclos do Programa em um distrito administrativo do município de São Paulo. Os sujeitos responderam, dentre outras, à questão “Como você avalia o processo de implementação do Programa Nacional de Melhoria do Acesso e da Qualidade nesta Unidade Básica de Saúde?” e da análise dos depoimentos emergiram as categorias “Percepção dos gestores quanto à implementação do Programa Nacional de Melhoria do Acesso e da Qualidade” e “Mudanças nos processos de trabalho a partir da implementação do Programa Nacional de Melhoria do Acesso e da Qualidade”. Resultados: Os gerentes reconheceram o Programa como uma proposta bem estruturada, que permite ampliar a visão gerencial nos serviços de saúde. O uso dos indicadores de qualidade foi evidenciado pelos entrevistados, mas pouco trabalhado e compreendido no cotidiano dos gestores e equipes. Os entrevistados demonstraram não compreender os conceitos de educação permanente e apoio institucional. A fase da avaliação externa foi considerada subjetiva e sem padronização, gerando dados que não contribuíram para avaliação das mudanças realizadas pelas equipes. Conclusão: Evidenciou-se um processo incipiente de incorporação da cultura avaliativa de forma sistematizada e como subsídio para a melhoria contínua da qualidade na Atenção Básica. Embora ainda haja distância entre as propostas do Programa Nacional de Melhoria do Acesso e da Qualidade e a prática nas Unidades Básicas de Saúde estudadas, o Programa favoreceu a organização dos processos de trabalho e contribuiu para direcionar o olhar dos gestores à prática das equipes e à própria atuação.Univ Fed Sao Paulo, Escola Paulista Enfermagem, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Escola Paulista Enfermagem, Sao Paulo, SP, BrazilWeb of Scienc

Novel triblock co-polymer nanofibre system as an alternative support for embryonic stem cells growth and pluripotency

Conventionally, embryonic stem cells (ESCs) are cultured on gelatin or over a mitotically inactivated monolayer of mouse embryonic fibroblasts (MEFsi). Considering the lack of versatile, non-animal-derived and inexpensive materials for that purpose, we aimed to find a biomaterial able to support ESC growth in a pluripotent state that avoids the need for laborious and time-consuming MEFsi culture in parallel with mouse ESC (mESC) culture. Undifferentiated mESCs were cultured in a new nanofibre material designed for ESC culture, which is based on the self-assembly of a triblock co-polymer, poly(ethyleneglycol-β-trimethylsilyl methacrylate-β-methacrylic acid), conjugated with the peptide glycine-arginine-glycine-aspartate-serine, to evaluate its potential application in ESC research. The morphology, proliferation, viability, pluripotency and differentiation potential of mESCs were assessed. Compared to conventional stem cell culture methodologies, the nanofibres promoted a higher increase in mESCs number, enhanced pluripotency and were able to support differentiation after long-term culture. This newly developed synthetic system allows the elimination of animal-derived matrices and provides an economic method of ESC culture, made of a complex network of nanofibres in a scale similar to native extracellular matrices, where the functional properties of the cells can be observed and manipulated