36 resultados para 641
Resumo:
Inconsistencies surrounding the prevalence levels of depression in later life suggest that the measurement of depression in older people may be problematic. The current study aimed to map responses to a depressive symptom scale, the Mental Health Index-5 (MHI-5) which is part of the Short form 36 (SF-36, Ware et al., 1993) against the diagnostic screening items of the Composite International Diagnostic Instrument-Short Form (CIDI-SF, Kessler et al., 1998) to examine disagreement rates across age groups. The study examined data from a national random sample of 10,641 participants living in Ireland, 58.8% were female and 19% were over 65 (SLÁN, 2007). CIDI-SF depression screening endorsement was lower in older groups, whereas mean MHI-5 depressive symptoms showed less change across age groups. Results showed that the odds of MHI-5 endorsers aged 18–44 endorsing CIDI-SF screening questions were 5 times and 4.5 times (dysphoria and anhedonia, respectively) greater than the odds of people aged 75 or more endorsing these items. Findings suggest that although the risk of depressive disorder may decrease with age, complex diagnostic screening questions may exaggerate lower rates of depression among older people.
Resumo:
Well-defined correlates of protective immunity are an essential component of rational vaccine development. Despite years of basic science and three HIV vaccine efficacy trials, correlates of immunological protection from HIV infection remain undefined. In December 2010, a meeting of scientists engaged in basic and translational work toward developing HIV-1 vaccines was convened. The goal of this meeting was to discuss current opportunities and optimal approaches for defining correlates of protection, both for ongoing and future HIV-1 vaccine candidates; specific efforts were made to engage young scientists. We discuss here the highlights from the meeting regarding the progress made and the way forward for a protective HIV-1 vaccine.
Resumo:
Existing chemical treatments to prevent biological damage to monuments often involve considerable amounts of potentially dangerous and even poisonous biocides. The scientific approach described in this paper aims at a drastic reduction in the concentration of biocide applications by a polyphasic approach of biocides combined with cell permeabilisers, polysaccharide and pigment inhibitors and a photodynamic treatment. A variety of potential agents were screened to determine the most effective combination. Promising compounds were tested under laboratory conditions with cultures of rock deteriorating bacteria, algae, cyanobacteria and fungi. A subsequent field trial involved two sandstone types with natural biofilms. These were treated with multiple combinations of chemicals and exposed to three different climatic conditions. Although treatments proved successful in the laboratory, field trials were inconclusive and further testing will be required to determine the most effective treatment regime. While the most effective combination of chemicals and their application methodology is still being optimised, results to date indicate that this is a promising and effective treatment for the control of a wide variety of potentially damaging organisms colonising stone substrates
Resumo:
Naturally occurring ices lie on both interstellar dust grains and on celestial objects, such as those in the outer Solar system. These ices are continuously subjected to irradiation by ions from the solar wind and/or cosmic rays, which modify their surfaces. As a result, new molecular species may form which can be sputtered off into space or planetary atmospheres. We determined the experimental values of sputtering yields for irradiation of oxygen ice at 10 K by singly (He+, C+, N+, O+ and Ar+) and doubly (C2 +, N2 + and O2 +) charged ions with 4 keV kinetic energy. In these laboratory experiments, oxygen ice was deposited and irradiated by ions in an ultra high vacuum chamber at low temperature to simulate the environment of space. The number of molecules removed by sputtering was observed by measurement of the ice thickness using laser interferometry. Preliminary mass spectra were taken of sputtered species and of molecules formed in the ice by temperature programmed desorption (TPD). We find that the experimental sputtering yields increase approximately linearly with the projectile ion mass (or momentum squared) for all ions studied. No difference was found between the sputtering yields for singly and doubly charged ions of the same atom within the experimental uncertainty, as expected for a process dominated by momentum transfer. The experimental sputter yields are in good agreement with values calculated using a theoretical model except in the case of oxygen ions. Preliminary studies have shown molecular oxygen as the dominant species sputtered and TPD measurements indicate ozone formation.
Resumo:
Polycyclic aromatic hydrocarbons (PAHs) are an important class of persistent organic pollutants (POPs) in the environment and accumulate in forest soils. These soils are often dominated by ectomycorrhizal (EcM) roots, but little is known about how EcM fungi degrade PAHs, or the overall effect of field colonized EcM roots on the fate of PAHs. The ability of eight EcM fungi to degrade PAHs in liquid culture spiked with 14C labelled PAHs was investigated. Microcosms were used to determine the impact of naturally colonized mycorrhizal pine seedlings on PAH mineralization and volatilization. Only two EcM fungi (Thelephora terrestris and Laccaria laccata) degraded at least one PAH and none were able to mineralize the PAHs in pure culture. Where degradation occurred, the compounds were only mono-oxygenated. EcM pine seedlings did not alter naphthalene mineralization or volatilization but retarded fluorene mineralization by 35% compared with unplanted, ectomycorrhizosphere soil inoculated, microcosms. The EcM fungi possessed limited PAH degrading abilities, which may explain why EcM dominated microcosms retarded fluorene mineralization. This observation is considered in relation to the 'Gadgil-effect', where retarded litter decomposition has been observed in the presence of EcM roots. © New Phytologist (2004).