HST optical polarimetry of the Vela pulsar & nebula

Polarisation measurements of pulsars offer an unique insight into the geometry of the emission regions in the neutron star magnetosphere. Therefore, they provide observational constraints on the different models proposed for the pulsar emission mechanisms. Optical polarisation data of the Vela pulsar was obtained from the {\em Hubble Space Telescope} ({\em HST}) archive. The data, obtained in two filters (F606W; central wavelength = 590.70 nm, and F550M; central wavelength = 558.15 nm), consists of a series of observations of the pulsar taken with the {\em HST}/Advanced Camera for Surveys (ACS) and covers a time span of 5 days. This data have been used to carry out the first high-spatial resolution and multi-epoch study of the polarisation of the pulsar. We produced polarisation vector maps of the region surrounding the pulsar and measured the degree of linear polarisation (P.D.) and the position angle (P.A.) of the pulsar's integrated pulse beam. %This yielded We obtained $\rm P.D.=8.1\%\pm0.7\%$ and \rm P.A.=146.3\degr\pm2.4\degr, averaged over the time span covered by these observations. These results not only confirm those originally obtained by \citeauthor{Wagner00} and \citeauthor{Mignani07}, both using the Very Large Telescope (VLT), but are of greater precision. Furthermore, we confirm that the P.A. of the pulsar polarisation vector is aligned with the direction of the pulsar proper-motion. The pulsar wind nebula (PWN) is undetected in polarised light as is the case in unpolarised light, down to a flux limit of 26.8 magnitudes arcsec$^{-2}$.Comment: 11 pages accepted for publication in MNRAS. arXiv admin note: text overlap with arXiv:1305.682

Employing pre-stress to generate finite cloaks for antiplane elastic waves

It is shown that nonlinear elastic pre-stress of neo-Hookean hyperelastic materials can be used as a mechanism to generate finite cloaks and thus render objects near-invisible to incoming antiplane elastic waves. This approach appears to negate the requirement for special cloaking metamaterials with inhomogeneous and anisotropic material properties in this case. These properties are induced naturally by virtue of the pre-stress. This appears to provide a mechanism for broadband cloaking since dispersive effects due to metamaterial microstructure will not arise.Comment: 4 pages, 2 figure

Long Duration Exposure Facility (LDEF) structural verification test report

Structural load tests on the Long Duration Exposure Facility's (LDEF) primary structure were conducted. These tests had three purposes: (1) demonstrate structural adequacy of the assembled LDEF primary structure when subjected to anticipated flight loads; (2) verify analytical models and methods used in loads and stress analysis; and (3) perform tests to comply with the Space Transportation System (STS) requirements. Test loads were based on predicted limit loads which consider all flight events. Good agreement is shown between predicted and observed load, strain, and deflection data. Test data show that the LDEF structure was subjected to 1.2 times limit load to meet the STS requirements. The structural adequacy of the LDEF is demonstrated

Pharmacokinetics and efficacy of oral versus intravenous mixed-micellar phylloquinone (vitamin K-1) in severe acute liver disease

Background/Aims: In patients with severe acute liver dysfunction, i.v. phylloquinone (vitamin K-1) may be given to exclude vitamin K deficiency, rather than impaired hepatic synthesis of coagulation factors alone, as the cause of the coagulopathy. However, there have been no studies of the pharmacokinetics or efficacy of i.v. or oral K-1 in such patients.Methods: 49 adults with severe acute liver disease were randomised double-blind to a single 10 mg dose of i.v. or oral mixed-micellar K-1, or placebo. Serum levels of phylloquinone and undercarboxylated prothrombin (PIVKA-II) were assessed before and after treatment.Results: At admission, 13 patients (27 %) had either low serum K-1 levels or elevated PIVKA-II concentrations, indicative of subclinical vitamin K deficiency. In the 16 patients who received i.v. K-1, there was one (6 %) treatment failure (K-1 rise < 10 ng/ml above baseline), compared with 12 of the 15 (80 %) who received oral K, (P < 0.0001). One patient in the placebo group developed overt vitamin K deficiency.Conclusions: A minority of patients with severe acute liver dysfunction have subclinical vitamin K deficiency at the time of presentation, which is corrected by a single dose of i.v. K-1. The intestinal absorption of mixed-micellar K, is unreliable in adults with severe acute liver dysfunction. (c) 2004 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved

Determination of the urinary aglycone metabolites of vitamin K by HPLC with redox-mode electrochemical detection

We describe a method for the determination of the two major urinary metabolites of vitamin K as the methyl esters of their agyclone structures, 2-methyl-3-(3-3-carboxymethylpropyl)-1,4-naphthoquinone (5C-side-chain metabolite) and 2-methyl-3-(5-carboxy-3-methyl-2-pentenyl)-1,4-naphthoquinone (7C-side-chain metabolite), by HPLC with electrochemical detection (ECD) in the redox mode. Urinary salts were removed by reversed-phase (C18) solid phase extraction (SPE) and the predominately conjugated vitamin K metabolites hydrolysed with methanolic HCl. The resultant carboxylic acid aglycones were quantitatively methylated with diazomethane and fractionated by normal-phase (silica) SPE. Final analysis was by reversed-phase (C18) HPLC with a methanol-aqueous mobile phase. Metabolites were detected by amperometric, oxidative ECD of their quinol forms, which were generated by post-column coulometric reduction at an upstream electrode. The assay gave excellent linearity (r2 typically = 0.999) and high sensitivity with an on-column detection limit of <3.5 fmol (<1pg). The inter-assay precision was typically 10%. Metabolite recovery was compared to that of an internal standard (2-methyl-3-(7'-carboxy-heptyl)-1,4-naphthoquinone), added to urine samples just before analysis. Using this methodology we confirmed that the 5C- and 7C-metabolite were major catabolites of both phylloquinone (vitamin K1) and menaquinones (vitamin K2) in humans. We propose that the measurement of urinary vitamin K metabolite excretion is a candidate non-invasive marker of total vitamin K status

The relationship between imagery type and collective efficacy in elite and non elite athletes

This study investigated the relationship between imagery function and individual perceptions of collective efficacy as a function of skill level. Elite (n = 70) and non elite (n = 71) athletes from a number of interactive team sports completed the Sport Imagery Questionnaire (SIQ) and the Collective Efficacy Inventory (CEI). Multiple hierarchical regression analysis was then used to examine which SIQ sub-scales predicted individual perceptions of collective efficacy. For the elite sample, Motivational General-Mastery (MG-M) imagery accounted for approximately 17% of the variance in collective efficacy scores. No significant predictions were observed in the non elite sample. The findings suggest MG-M imagery as a potential technique to improve levels of collective efficacy although competitive level may moderate the effectiveness of such intervention

PRECISION AGRICULTURE, WHOLE FIELD FARMING AND IRRIGATION PRACTICES: A PRODUCTION RISK ANALYSIS

One of the potential management practices of precision agriculture (PA) is the capability of varying input application rate across a field. A potential benefit of that practice is the reduction in yield variability. Temporal reduction in yield variability can also be achieved through irrigation practices. Combining both practices should lead to a reduction of the yield risk faced by the farmer. In this study, variable rate application of nutrients will include to nitrogen, potassium and phosphate. Mathematical programming techniques will be used in a standard E-V framework to analyze the ability of PA and/or irrigation to reduce production risk.Risk and Uncertainty,

Implications of the Optical Observations of Neutron Stars

We show that observations of pulsars with pulsed optical emission indicate that the peak flux scales according to the magnetic field strength at the light cylinder. The derived relationships indicate that the emission mechanism is common across all of the observed pulsars with periods ranging from 33ms to 385 ms and ages of 1000-300,000 years. It is noted that similar trends exist for $\gamma$ ray pulsars. Furthermore the model proposed by Pacini (1971) and developed by Pacini and Salvati (1983,1987) still has validity and gives an adequate explanation of the optical phenomena.Comment: 23 pages, 6 figures, accepted for publication in the Astrophysical Journa

An experimental study investigating the ability of volunteers to identify squirrel species from tail–hair samples

Un estudio experimental sobre la capacidad de los voluntarios de reconocer las especies de ardilla a partir de muestras de pelo de la cola Las trampas de pelo, que permiten recoger los pelos de la nuca, se utilizan ampliamente para establecer la presencia de la ardilla común (Sciurus vulgaris) y la ardilla gris (Sciurus carolinensis). No obstante, es un método que requiere mucho tiempo y se presta a errores de identificación. Una alternativa es recoger pelos de la cola mediante cintas adhesivas colocadas en postes que sostienen un cebo en la parte superior. Sin embargo, no existen datos sobre la precisión de la identificación del pelo de la cola. En este estudio se informa de un experimento en que se ofreció una breve sesión formativa a las personas antes de que identificaran las muestras de pelo de las cuatro especies. El índice de identificación correcta fue del 96,5% para los pelos de la ardilla gris y del 77,5% para los de la ardilla común, lo que sugiere que los pelos de la cola pueden proporcionar un método rápido, fácil y preciso de identificar ambas especies.Hair–tubes, collecting nape hairs, are widely used for establishing the presence of red (Sciurus vulgaris) and grey (Sciurus carolinensis) squirrels. However it is time–consuming and prone to identification errors. An alternative is to collect tail hairs from sticky pads on baited poles. However, there is no evidence concerning identification accuracy of tail hairs. This study reports an experiment in which subjects underwent a short training session before identifying hair samples from four species. There was a 96.5% correct identification rate for grey squirrel hairs, and 77.5% for red squirrels, which suggests that tail hairs collection may provide a quick, easy and accurate method of identification for both species.Un estudio experimental sobre la capacidad de los voluntarios de reconocer las especies de ardilla a partir de muestras de pelo de la cola Las trampas de pelo, que permiten recoger los pelos de la nuca, se utilizan ampliamente para establecer la presencia de la ardilla común (Sciurus vulgaris) y la ardilla gris (Sciurus carolinensis). No obstante, es un método que requiere mucho tiempo y se presta a errores de identificación. Una alternativa es recoger pelos de la cola mediante cintas adhesivas colocadas en postes que sostienen un cebo en la parte superior. Sin embargo, no existen datos sobre la precisión de la identificación del pelo de la cola. En este estudio se informa de un experimento en que se ofreció una breve sesión formativa a las personas antes de que identificaran las muestras de pelo de las cuatro especies. El índice de identificación correcta fue del 96,5% para los pelos de la ardilla gris y del 77,5% para los de la ardilla común, lo que sugiere que los pelos de la cola pueden proporcionar un método rápido, fácil y preciso de identificar ambas especies