Spin-transfer switching and low-field precession in exchange-biased spin valve nano-pillars

Using a three-dimensional focused-ion beam lithography process we have fabricated nanopillar devices which show spin transfer torque switching at zero external magnetic fields. Under a small in-plane external bias field, a field-dependent peak in the differential resistance versus current is observed similar to that reported in asymmetrical nanopillar devices. This is interpreted as evidence for the low-field excitation of spin waves which in our case is attributed to a spin-scattering asymmetry enhanced by the IrMn exchange bias layer coupled to a relatively thin CoFe fixed layer.Comment: 11 pages, 4 figures. To appear in APL, April 200

Marked increase in PROP taste responsiveness following oral supplementation with selected salivary proteins or their related free amino acids

The genetic predisposition to taste 6-n-propylthiouracil (PROP) varies among individuals and is associated with salivary levels of Ps-1 and II-2 peptides, belonging to the basic proline-rich protein family (bPRP). We evaluated the role of these proteins and free amino acids that selectively interact with the PROP molecule, in modulating bitter taste responsiveness. Subjects were classified by their PROP taster status based on ratings of perceived taste intensity for PROP and NaCl solutions. Quantitative and qualitative determinations of Ps-1 and II-2 proteins in unstimulated saliva were performed by HPLC-ESI-MS analysis. Subjects rated PROP bitterness after supplementation with Ps-1 and II-2, and two amino acids (L-Arg and L-Lys) whose interaction with PROP was demonstrated by (1)H-NMR spectroscopy. ANOVA showed that salivary levels of II-2 and Ps-1 proteins were higher in unstimulated saliva of PROP super-tasters and medium tasters than in non-tasters. Supplementation of Ps-1 protein in individuals lacking it in saliva enhanced their PROP bitter taste responsiveness, and this effect was specific to the non-taster group.(1)H-NMR results showed that the interaction between PROP and L-Arg is stronger than that involving L-Lys, and taste experiments confirmed that oral supplementation with these two amino acids increased PROP bitterness intensity, more for L-Arg than for L-Lys. These data suggest that Ps-1 protein facilitates PROP bitter taste perception and identifies a role for free L-Arg and L-Lys in PROP tasting

Air-Sea Exchange of Biogenic Volatile Organic Compounds and the Impact on Aerosol Particle Size Distributions

We report simultaneous, underway eddy covariance measurements of the vertical flux of isoprene, total monoterpenes, and dimethyl sulfide (DMS) over the Northern Atlantic Ocean during fall. Mean isoprene and monoterpene sea-to-air vertical fluxes were significantly lower than mean DMS fluxes. While rare, intense monoterpene sea-to-air fluxes were observed, coincident with elevated monoterpene mixing ratios. A statistically significant correlation between isoprene vertical flux and short wave radiation was not observed, suggesting that photochemical processes in the surface microlayer did not enhance isoprene emissions in this study region. Calculations of secondary organic aerosol production rates (PSOA) for mean isoprene and monoterpene emission rates sampled here indicate that PSOA is on average <0.1 μg m−3 d−1. Despite modest PSOA, low particle number concentrations permit a sizable role for condensational growth of monoterpene oxidation products in altering particle size distributions and the concentration of cloud condensation nuclei during episodic monoterpene emission events from the ocean

Development of interfering RNA agents to inhibit SARS-associated coronavirus infection and replication.

published_or_final_versio

Referenciação pediátrica: que realidade?

Mesmo após a reestruturação de acesso à Urgência Pediátrica que teve inicio em Março de 2000, a afluência directa à Urgência Pediátrica no Hospital Fernando Fonseca sem referenciação médica é uma realidade diária. O presente estudo pretendeu determinar os motivos que levam as crianças à urgência daqueÌe hospital. Foi um estudo observacional descritivo, cuja recolha de dados ocorreu entre os dias 8 e 16 de Outubro de 2001 (apenas dias úteis) na Urgência Pediátrica (end-point 100 crianças). A maioria das crianças analisadas pertence aos Centros de Saúde do Cacém, Queluz e Mem Martins. O principal motivo da ida directa é a vontade dos acompanhantes, sendo a febre o principal motivo clínico da vinda das crianças. Não foi possível estabelecer qualquer relação entre o motivo para a vinda directa e a raça, escolaridade e o facto de ser primeiro filho. A maior parte das crianças teve alta para o domicílio (82%), sem necessitar de cuidados no hospital que não pudessem ter sido obtidos no Centro de Saúde da área. Apenas 18% necessitaram de tratamento hospitalar e destes seis porcento ficaram internados. Assim, para a maioria dos doentes (82%) é correcto ir ao Centro de Saúde e ser observado apenas pelo médico de Cuidados Primários. Tal representaria melhor utilização dos recursos médicos disponíveis com diminuição de custos para Sistema Nacional de Saúd