Un estudio preliminar sobre la biología molecular de especies de Zamia L. (Cycadales: Zamiaceae) en Panamá

La identificación taxonómica de las especies descritas de Zamia de Panamá está basada principalmente en la morfología de las hojas y en algunas características reproductivas. Con el propósito de utilizar criterios adicionales se secuenció la región ITS2 comprendidas entre los genes de rDNA 18S, 5.8S y 26S. Los resultados preliminares de la taxonomía molecular de las especies descritas de Zamia de Panamá, basados en la secuencia ITS2 del ADN ribosomal nuclear, muestran 3 cladogramas pobremente resueltos. El mas parsimonioso señala dos clados: Un clado basal que contiene 3 especies de la región este del Istmo "Clado Panamá Este" y el otro que incluye el resto de las especies con distribución desde el centro hacia al oeste del área canalera "Clado Panamá Oeste", exceptuando las provincias de Herrera y Los Santos, en las cuales, quizás por motivo de deforestación de larga data, no se han encontrado hasta la fecha cícadas. Además, los resultados indican que este gen por si sólo no es el mas indicado para establecer diferencias filogenéticas interespecífica para la mayoría de las especies, no así para las especies Z. dressleri, Z. pseudoparasitica, Z. obliqua, Z. lindleyi y Z. skinneri, las cuales encuentran en ramas resueltas. Es importante señalar que Z obliqua se ubica en el clado Panamá Este, pero, por su amplia distribución, se refleja en ambos clados. Como se ha visto en trabajos similares previos (Caputo et al, 2004; Taylor et al., 2012), el patrón de relaciones filogenéticas en Zamia es altamente congruente con su distribución su geográfica y no con semejanzas morfológicas

Persistence of low disease activity after tumour necrosis factor inhibitor (TNFi) discontinuation in patients with psoriatic arthritis.

OBJECTIVE: To determine the duration of clinical benefit among patients with psoriatic arthritis (PsA) discontinuing tumour necrosis factor inhibitor (TNFi) therapy while in low disease activity (LDA), and to identify patient characteristics associated with prolonged clinical benefit. METHODS: We performed an observational cohort study assessing patients with PsA from the Consortium of Rheumatology Researchers of North America (CORRONA) registry who had discontinued TNFi after achieving LDA, defined as clinical disease activity index (CDAI) score ≤10 and physician\u27s global assessment (PGA) of skin psoriasis ≤20/100. Kaplan-Meier method was used to estimate the duration of clinical benefit. RESULTS: Of the 5945 patients with PsA in CORRONA, 302 patients had discontinued TNFi (n=325) while in LDA and had follow-up data available. At time of discontinuation, mean PsA duration was 9.8 years, mean CDAI was 3.9, and mean duration of TNFi use was 1.5 years; 52.6% of patients had discontinued their first TNFi. Median time to loss of benefit was 29.2 months. 179 (55.1%) patients had persistent benefit at their previous clinic visit. An increased risk of losing clinical benefit was seen among patients with higher disease activity at discontinuation (CDAI≥3.2 vs CONCLUSIONS: Patients with PsA who achieve LDA may maintain clinical benefit after discontinuation of TNFi therapy

Tanque hidráulico experimental para cálculo de perda de carga em tubulações

O artigo descreve a construção de um tanque hidráulico para o cálculo da perda de carga em dutos cilíndricos retos e a execução dos ensaios. O tanque possui estrutura simples, baixo custo, robustez e versatilidade necessárias para a realização de ensaios de fácil execução, baseados no registro dos tempos associados à variação da altura da coluna de água num tubo vertical. A utilização deste equipamento em aulas experimentais mostrou-se muito eficaz, possibilitando a comprovação de resultados teóricos a partir da utilização de modelos reais. Os resultados obtidos são apresentados em planilhas eletrônicas, cuja elaboração baseou-se na aplicação dos princípios de conservação de massa e energia no escoamento de fluidos viscosos, e nas equações de perda de carga distribuída e localizada. O experimento proposto constitui uma ferramenta pedagógica interessante, tendo em vista que sua execução requer a participação ativa dos alunos na realização dos ensaios e na execução de cálculos. A rotina de cálculos, visando comparar valores experimentais perda de carga obtidos experimentalmente com valores teóricos, abrange uma série de conceitos e equações da Mecânica dos Fluidos, propiciando que a aprendizagem desse conteúdo seja feita a partir de um problema real.

High-precision photometry by telescope defocussing. III. The transiting planetary system WASP-2

We present high-precision photometry of three transits of the extrasolar planetary system WASP-2, obtained by defocussing the telescope, and achieving point-to-point scatters of between 0.42 and 0.73 mmag. These data are modelled using the JKTEBOP code, and taking into account the light from the recently-discovered faint star close to the system. The physical properties of the WASP-2 system are derived using tabulated predictions from five different sets of stellar evolutionary models, allowing both statistical and systematic errorbars to be specified. We find the mass and radius of the planet to be M_b = 0.847 +/- 0.038 +/- 0.024 Mjup and R_b = 1.044 +/- 0.029 +/- 0.015 Rjup. It has a low equilibrium temperature of 1280 +/- 21 K, in agreement with a recent finding that it does not have an atmospheric temperature inversion. The first of our transit datasets has a scatter of only 0.42 mmag with respect to the best-fitting light curve model, which to our knowledge is a record for ground-based observations of a transiting extrasolar planet.Comment: Accepted for publication in MNRAS. 9 pages, 3 figures, 10 table

First search for gravitational waves from the youngest known neutron star

We present a search for periodic gravitational waves from the neutron star in the supernova remnant Cassiopeia A. The search coherently analyzes data in a 12 day interval taken from the fifth science run of the Laser Interferometer Gravitational-Wave Observatory. It searches gravitational-wave frequencies from 100 to 300 Hz and covers a wide range of first and second frequency derivatives appropriate for the age of the remnant and for different spin-down mechanisms. No gravitational-wave signal was detected. Within the range of search frequencies, we set 95% confidence upper limits of (0.7–1.2) × 10^(−24) on the intrinsic gravitational-wave strain, (0.4–4) × 10^(−4) on the equatorial ellipticity of the neutron star, and 0.005–0.14 on the amplitude of r-mode oscillations of the neutron star. These direct upper limits beat indirect limits derived from energy conservation and enter the range of theoretical predictions involving crystalline exotic matter or runaway r-modes. This paper is also the first gravitational-wave search to present upper limits on the r-mode amplitude

Upper Limits on a Stochastic Background of Gravitational Waves

The Laser Interferometer Gravitational-Wave Observatory has performed a third science run with much improved sensitivities of all three interferometers. We present an analysis of approximately 200 hours of data acquired during this run, used to search for a stochastic background of gravitational radiation. We place upper bounds on the energy density stored as gravitational radiation for three different spectral power laws. For the flat spectrum, our limit of Ω_0<8.4×10^(-4) in the 69–156 Hz band is ~10^5 times lower than the previous result in this frequency range