Fibrils and nanotubes assembled from a modified amyloid-β peptide fragment differ in the packing of the same β-sheet building blocks

The peptide AAKLVFF assembles into fibrils in water and nanotubes in methanol. Solid-state NMR data are consistent with fibrils constructed from β-sheet bilayers and nanotubes bounded by a wall of offset β-sheet monolayers. Remarkably distinct morphologies are thus traced to subtle differences in the arrangement of the same fundamental building blocks.

The interval and indoor playmaking

Although early modern acting companies were adept at using different kinds of venue, performing indoors imposed a significant change in practice. Since indoor theatres required artificial lighting to augment the natural light admitted via windows, candles were employed; but the technology was such that candles could not last untended throughout an entire performance. Performing indoors thus introduced a new component into stage practice: the interval. This article explores what extant evidence (such as it is) might tell us about the introduction of act breaks, how they may have worked, and the implications for actors, audiences and dramatists. Ben Jonson's scripting of the interval in two late plays, The Staple of News and The Magnetic Lady, is examined for what it may suggest about actual practice, and the ways in which the interval may have been considered integral to composition and performance is explored through a reading of Middleton and Rowley's The Changeling. The interval offered playwrights a form of structural punctuation, drawing attention to how acts ended and began; actors could use the space to bring on props for use in the next act; spectators might use the pause between acts to reflect on what had happened and, perhaps, anticipate what was to come; and stage-sitters, the evidence indicates, often took advantage of the hiatus in the play to assert their presence in the space to which all eyes naturally were drawn.

Insights into the molecular architecture of a peptide nanotube using FTIR and solid-state NMR spectroscopic measurements on an aligned sample

The self-assembly of proteins and peptides into b-sheet-rich amyloid fibers is a process that has gained notoriety because of its association with human diseases and disorders. Spontaneous self-assembly of peptides into nonfibrillar supramolecular structures can also provide a versatile and convenient mechanism for the bottom-up design of biocompatible materials with functional properties favoring a wide range of practical applications.[1] One subset of these fascinating and potentially useful nanoscale constructions are the peptide nanotubes, elongated cylindrical structures with a hollow center bounded by a thin wall of peptide molecules.[2] A formidable challenge in optimizing and harnessing the properties of nanotube assemblies is to gain atomistic insight into their architecture, and to elucidate precisely how the tubular morphology is constructed from the peptide building blocks. Some of these fine details have been elucidated recently with the use of magic-angle-spinning (MAS) solidstate NMR (SSNMR) spectroscopy.[3] MAS SSNMR measurements of chemical shifts and through-space interatomic distances provide constraints on peptide conformation (e.g., b-strands and turns) and quaternary packing. We describe here a new application of a straightforward SSNMR technique which, when combined with FTIR spectroscopy, reports quantitatively on the orientation of the peptide molecules within the nanotube structure, thereby providing an additional structural constraint not accessible to MAS SSNMR.

Estudo geotécnico sobre a erodibilidade de solos residuais não saturados

A erodibilidade, particularizada como a susceptibilidade a erosão hídrica por fluxo superficial concentrado, é uma das propriedades de comportamento dos solos de maior complexidade pelo grande número de variáveis intervenientes. Estudada por diferentes áreas do conhecimento (Agronomia, Hidráulica, Geologia de Engenharia e Engenharia Geotécnica), tem no meio geotécnico a maior lacuna na sua quantificação e entendimento dos mecanismos envolvidos. O presente trabalho apresenta um estudo sobre a erodibilidade de solos residuais tropicais e subtropicais não saturados a partir de quatro perfis representativos dos processos erosivos e solos envolvidos na Região Metropolitana de Porto Alegre. Os solos dos principais horizontes de cada um destes perfis foram caracterizados física, química e mineralogicamente. As propriedades de resistência ao cisalhamento e colapsibilidade foram avaliadas por ensaios de cisalhamento direto convencionais e com controle de sucção e por ensaios de colapsibilidade em oedômetros, respectivamente. A erodibilidade foi avaliada em laboratório, diretamente por meio de ensaios de Inderbitzen e indiretamente por diferentes critérios e parâmetros baseados em outras características físicas e propriedades dos solos. A análise conjunta do comportamento dos solos em campo frente a erosão, da avaliação direta e indireta da erodibilidade e das propriedades geomecânicas investigadas conduziram à formulação de uma proposta de abordagem geotécnica para a erodibilidade dos solos residuais tropicais e subtropicais não saturados. Nesta proposta destaca–se a avaliação direta da erodibilidade por ensaios de Inderbitzen e a indicação de solos potencialmente erodíveis baseada no teor de finos, na plasticidade, no parâmetro K da USLE, na Razão de Dispersão de Middleton, na classificação e critério de erodibilidade MCT e na variação da coesão com a saturação pelo parâmetro variação de coesão (Δc) proposto. A proposta de abordagem geotécnica para a previsão da erodibilidade dos solos visa dotar o engenheiro geotécnico de uma ferramenta destinada à avaliação do potencial erosivo dos terrenos antes de uma iniciativa de ocupação urbana ou implantação de qualquer outra obra de engenharia. Esta avaliação é o passo inicial no direcionamento de medidas preventivas e que visem minimizar o impacto da obra ao meio físico natural, no que se refere a erosão hídrica por fluxo superficial concentrado.

A utilização transnacional e complementar de serviços de saúde por emigrantes de Governador Valadares-MG nos Estados Unidos e no Brasil

Para explorar as necessidades, o acesso e a utilização dos serviços de saúde dos emigrantes valadarenses nos EUA e em Governador Valadares, assim como a influência desta demanda na oferta de serviços de saúde na cidade mineira, o presente estudo adotou três linhas de investigação. A primeira relacionou a percepção dos emigrantes da amostra, a respeito dos profissionais e dos serviços de saúde utilizados nos EUA e em Governador Valadares. A segunda concentrou-se na percepção dos profissionais de saúde selecionados a respeito das características da demanda do emigrante, assim como da sua influência na oferta de serviços de saúde em Valadares. A última, uma pesquisa documental na Vigilância Sanitária, contabilizou as aberturas anuais de serviços de saúde da localidade. As informações recolhidas junto aos emigrantes valadarenses permitem afirmar a viabilidade do acesso e da utilização dos serviços de saúde subsidiados pelos governos federal, estaduais e municipais nos Estados de Massachusetts e em Connecticut, onde se concentram mais da metade dos valadarenses residentes nos EUA. Seja pelas restrições governamentais ao acesso aos serviços de saúde norte-americanos, pelo custo da assistência em saúde nos EUA, ou mesmo por fatores culturais, o emigrante valadarense, ao retornar ou visitar a cidade de origem, busca os profissionais e os serviços de saúde da localidade. A análise da pesquisa documental, com as informações acerca da abertura de serviços privados de saúde e das entrevistas com os profissionais da área da cidade, revelou a existência de uma relação entre a demanda do emigrante e o crescimento de abertura de serviços privados de saúde ocorrida a partir da segunda metade da década de 90.

O acesso aos serviços de saúde por emigrantes brasileiros nos Estados Unidos

A análise do atual contexto político e econômico existente nos EUA, que envolve o acesso e utilização de serviços de saúde pelos imigrantes, diz respeito aos mais de 20 milhões de indivíduos estrangeiros que residem naquele país e não possuem seguro de saúde. Essa população corresponde a 43,8% de 46 milhões de pessoas que não possuem cobertura de provedores privados de saúde nos EUA, sendo 10,5 milhões residentes sem a documentação exigida para viver no País. Para explorar as necessidades, o acesso e a utilização dos serviços de saúde americanos pelos emigrantes de Governador Valadares, MG, Brasil, o presente estudo entrevistou uma amostra de 14 emigrantes valadarenses selecionada por meio da técnica bola de neve. Foram elaboradas questões relacionadas à documentação, local de residência, profissões exercidas, necessidade, acesso e utilização de serviços de saúde. As informações recolhidas junto aos emigrantes residentes nos Estados de Massachusetts e Connecticut permitem afirmar a viabilidade do acesso e da utilização dos serviços de saúde subsidiados pelos governos federal e estaduais e de organizações não governamentais.

Detecção e diferenciação do vírus da bronquite infecciosa pela técnica de imunocaptura-RT-PCR E RFLP

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento da técnica de RT-PCR em tempo real para detecção e diferenciação de estirpes do vírus da bronquite infecciosa das galinhas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Narrow-band search of continuous gravitational-wave signals from Crab and Vela pulsars in Virgo VSR4 data

In this paper we present the results of a coherent narrow-band search for continuous gravitational-wave signals from the Crab and Vela pulsars conducted on Virgo VSR4 data. In order to take into account a possible small mismatch between the gravitational-wave frequency and two times the star rotation frequency, inferred from measurement of the electromagnetic pulse rate, a range of 0.02 Hz around two times the star rotational frequency has been searched for both the pulsars. No evidence for a signal has been found and 95% confidence level upper limits have been computed assuming both that polarization parameters are completely unknown and that they are known with some uncertainty, as derived from x-ray observations of the pulsar wind torii. For Vela the upper limits are comparable to the spin-down limit, computed assuming that all the observed spin-down is due to the emission of gravitational waves. For Crab the upper limits are about a factor of 2 below the spin-down limit, and represent a significant improvement with respect to past analysis. This is the first time the spin-down limit is significantly overcome in a narrow-band search.

Directed search for gravitational waves from Scorpius X-1 with initial LIGO data

We present results of a search for continuously emitted gravitational radiation, directed at the brightest low-mass x-ray binary, Scorpius X-1. Our semicoherent analysis covers 10 days of LIGO S5 data ranging from 50-550 Hz, and performs an incoherent sum of coherent F-statistic power distributed amongst frequency-modulated orbital sidebands. All candidates not removed at the veto stage were found to be consistent with noise at a 1% false alarm rate. We present Bayesian 95% confidence upper limits on gravitational-wave strain amplitude using two different prior distributions: a standard one, with no a priori assumptions about the orientation of Scorpius X-1; and an angle-restricted one, using a prior derived from electromagnetic observations. Median strain upper limits of 1.3 x 10(-24) and 8 x 10(-25) are reported at 150 Hz for the standard and angle-restricted searches respectively. This proof-of-principle analysis was limited to a short observation time by unknown effects of accretion on the intrinsic spin frequency of the neutron star, but improves upon previous upper limits by factors of similar to 1.4 for the standard, and 2.3 for the angle-restricted search at the sensitive region of the detector.

Advanced LIGO

The Advanced LIGO gravitational wave detectors are second-generation instruments designed and built for the two LIGO observatories in Hanford, WA and Livingston, LA, USA. The two instruments are identical in design, and are specialized versions of a Michelson interferometer with 4 km long arms. As in Initial LIGO, Fabry-Perot cavities are used in the arms to increase the interaction time with a gravitational wave, and power recycling is used to increase the effective laser power. Signal recycling has been added in Advanced LIGO to improve the frequency response. In the most sensitive frequency region around 100 Hz, the design strain sensitivity is a factor of 10 better than Initial LIGO. In addition, the low frequency end of the sensitivity band is moved from 40 Hz down to 10 Hz. All interferometer components have been replaced with improved technologies to achieve this sensitivity gain. Much better seismic isolation and test mass suspensions are responsible for the gains at lower frequencies. Higher laser power, larger test masses and improved mirror coatings lead to the improved sensitivity at mid and high frequencies. Data collecting runs with these new instruments are planned to begin in mid-2015.

Regulation of ventral surface CO2/H+-sensitive neurons by purinergic signalling

Central chemoreception is the mechanism by which the brain regulates breathing in response to changes in tissue CO2/H+. Abrainstemregion called the retrotrapezoid nucleus (RTN) contains a population of CO2/H+-sensitive neurons that appears to function as an important chemoreceptor. Evidence also indicates that CO2-evoked ATP release from RTN astrocytes modulates activity of CO2/H+-sensitive neurons; however, the extent to which purinergic signalling contributes to chemoreception by RTN neurons is not clear and the mechanism(s) underlying CO2/H+-evoked ATP release is not fully elucidated. The goals of this study are to determine the extent to which ATP contributes to RTN chemoreception both in vivo and in vitro, andwhether purinergic drive to chemoreceptors relies on extracellularCa(2+) or gap junction hemichannels. We also examine the possible contribution of P2Y1 receptors expressed in theRTNto the purinergic drive to breathe. We showthat purinergic signalling contributes, in part, to the CO2/H+ sensitivity of RTN neurons. In vivo, phrenic nerve recordings of respiratory activity in adult rats show that bilateral injections of pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (PPADS, a P2 receptor blocker) decreased the ventilatory response to CO2 by 30%. In vitro, loose-patch recordings from RTN neurons show that P2 receptor blockers decreased responsiveness to both 10% and 15% CO2 also by 30%. In the slice, the contribution of purinergic signalling to RTN chemoreception did not increase with temperature (22-35 degrees C) and was retained in low extracellular Ca2+ medium. Conversely, the gap junction blockers carbenoxolone and cobalt decreased neuronal CO2/H+ sensitivity by an amount similar to P2 receptor antagonists. Inhibition of the P2Y1 receptor in the RTN had no effect on CO2 responsivness in vitro or in vivo; thus, the identity of P2 receptors underlying the purinergic component of RTN chemoreception remains unknown. These results support the possibility that CO2/H+-evoked ATP release is mediated by a mechanism involving gap junction hemichannels.

The influence of large-scale circulation, transient and local processes on the seasonal circulation of the Eastern Brazilian Shelf, 13 degrees S

The circulation at the Eastern Brazilian Shelf (EBS), near 13 degrees S, is discussed in terms of the currents and hydrography, associating large-scale circulation, transient and local processes to establish a regional picture of the EBS circulation. The results show that the circulation within the continental shelf and slope region is strongly affected by the seasonal changes in the wind field and mesa/large-scale circulation. Transient processes associated to the passage of Cold Front systems or meso-scale activity and the presence of a local canyon add more complexity to the system. During the austral spring and summer seasons, the prevailing upwelling favorable winds blowing from E-NE were responsible for driving southwestward shelf currents. The interaction with the Western Boundary Current (the Brazil Current), especially during summer, was significant and a considerable vertical shear in the velocity field was observed at the outer shelf. The passage of a Cold Front system during the springtime caused a complete reversal of the mean flow and contributed to the deepening of the Mixed Layer Depth (MLD). In addition, the presence of Salvador Canyon, subject to an upwelling favorable boundary current, enhanced the upwelling system, when compared to the upwelling observed at the adjacent shelf. During the austral autumn and winter seasons the prevailing downwelling favorable winds blowing from the SE acted to total reverse the shelf circulation, resulting in a northeastward flow. The passage of a strong Cold Front, during the autumn season, contributed not only to the strengthening of the flow but also to the deepening of the MLD. The presence of the Salvador Canyon, when subject to a downwelling favorable boundary current, caused an intensification of the downwelling process. Interestingly, the alongshore velocity at the shelf region adjacent to the head of the canyon was less affected when compared to the upwelling situation.

Cryptic species in the cosmopolitan Bugulan eritina complex (Bryozoa,Cheilostomata)

Previous analyses of the mitochondrial gene cytochrome c oxidase subunit 1 (COI) and γ-proteobacterial endosymbiont diversity have suggested that the marine bryozoan Bugula neritina is a complex of three cryptic species, namely Types S, D and N. Types D and N were previously reported to have restricted distributions along California (western USA) and Delaware and Connecticut (eastern USA), respectively, whereas Type S is considered widespread in tropical, subtropical and temperate regions due to anthropogenic transport. Here, Bayesian species delimitation analysis of a data set composed of two mitochondrial (COI and large ribosomal RNA subunit [16S]) and two nuclear genes (dynein light chain roadblock type-2 protein [DYN] and voltage-dependent anion-selective channel protein [VDAC]) demonstrated that Types S, D and N correspond to three biological species. This finding was significantly supported, in spite of the combinations of priors applied for ancestral population size and root age. Furthermore, COI sequences were used to assess the introduction patterns of the cosmopolitan Type S species. Two COI haplotypes of Type S (S1a and S1d) were found occurring at a global scale. Mantel tests showed correlation between these haplotypes and local sea surface temperature tolerance. Accordingly, the distributions of Type S haplotypes may reflect intraspecific temperature tolerance variation, in addition to the role of introduction vectors. Finally, we show that the Type N may also have been introduced widely, as this species was found for the first time in Central California and north-eastern Australia.

P2Y1 receptors expressed by C1 neurons determine peripheral chemoreceptor modulation of breathing, sympathetic activity, and blood pressure

Catecholaminergic C1 cells of the rostral ventrolateral medulla (RVLM) are key determinants of the sympathoexcitatory response to peripheral chemoreceptor activation. Overactivation of this reflex is thought to contribute to increased sympathetic activity and hypertension; however, molecular mechanisms linking peripheral chemoreceptor drive to hypertension remain poorly understood. We have recently determined that activation of P2Y1 receptors in the RVLM mimicked effects of peripheral chemoreceptor activation. Therefore, we hypothesize that P2Y1 receptors regulate peripheral chemoreceptor drive in this region. Here, we determine whether P2Y1 receptors are expressed by C1 neurons in the RVLM and contribute to peripheral chemoreceptor control of breathing, sympathetic activity, and blood pressure. We found that injection of a specific P2Y1 receptor agonist (MRS2365) into the RVLM of anesthetized adult rats increased phrenic nerve activity (≈55%), sympathetic nerve activity (38±6%), and blood pressure (23±1 mm Hg), whereas application of a specific P2Y1 receptor antagonist (MRS2179) decreased peripheral chemoreceptor–mediated activation of phrenic nerve activity, sympathetic nerve activity, and blood pressure. To establish that P2Y1 receptors are expressed by C1 cells, we determine in the brain slice preparation using cell-attached recording techniques that cells responsive to MRS2365 are immunoreactive for tyrosine hydroxylase (a marker of C1 cells), and we determine in vivo that C1-lesioned animals do not respond to RVLM injection of MRS2365. These data identify P2Y1 receptors as key determinants of peripheral chemoreceptor regulation of breathing, sympathetic nerve activity, and blood pressure.