30 research outputs found
A review of elliptical and disc galaxy structure, and modern scaling laws
A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their
models to describe the radial distribution of stars in `nebulae'. This article
reviews the progress since then, providing both an historical perspective and a
contemporary review of the stellar structure of bulges, discs and elliptical
galaxies. The quantification of galaxy nuclei, such as central mass deficits
and excess nuclear light, plus the structure of dark matter halos and cD galaxy
envelopes, are discussed. Issues pertaining to spiral galaxies including dust,
bulge-to-disc ratios, bulgeless galaxies, bars and the identification of
pseudobulges are also reviewed. An array of modern scaling relations involving
sizes, luminosities, surface brightnesses and stellar concentrations are
presented, many of which are shown to be curved. These 'redshift zero'
relations not only quantify the behavior and nature of galaxies in the Universe
today, but are the modern benchmark for evolutionary studies of galaxies,
whether based on observations, N-body-simulations or semi-analytical modelling.
For example, it is shown that some of the recently discovered compact
elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to
appear in "Planets, Stars and Stellar
Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references
incl. many somewhat forgotten, pioneer papers. Original submission to
Springer: 07-June-201
Automated Detection of External Ventricular and Lumbar Drain-Related Meningitis Using Laboratory and Microbiology Results and Medication Data
OBJECTIVE: Monitoring of healthcare-associated infection rates is important for infection control and hospital benchmarking. However, manual surveillance is time-consuming and susceptible to error. The aim was, therefore, to develop a prediction model to retrospectively detect drain-related meningitis (DRM), a frequently occurring nosocomial infection, using routinely collected data from a clinical data warehouse. METHODS: As part of the hospital infection control program, all patients receiving an external ventricular (EVD) or lumbar drain (ELD) (2004 to 2009; n = 742) had been evaluated for the development of DRM through chart review and standardized diagnostic criteria by infection control staff; this was the reference standard. Children, patients dying <24 hours after drain insertion or with <1 day follow-up and patients with infection at the time of insertion or multiple simultaneous drains were excluded. Logistic regression was used to develop a model predicting the occurrence of DRM. Missing data were imputed using multiple imputation. Bootstrapping was applied to increase generalizability. RESULTS: 537 patients remained after application of exclusion criteria, of which 82 developed DRM (13.5/1000 days at risk). The automated model to detect DRM included the number of drains placed, drain type, blood leukocyte count, C-reactive protein, cerebrospinal fluid leukocyte count and culture result, number of antibiotics started during admission, and empiric antibiotic therapy. Discriminatory power of this model was excellent (area under the ROC curve 0.97). The model achieved 98.8% sensitivity (95% CI 88.0% to 99.9%) and specificity of 87.9% (84.6% to 90.8%). Positive and negative predictive values were 56.9% (50.8% to 67.9%) and 99.9% (98.6% to 99.9%), respectively. Predicted yearly infection rates concurred with observed infection rates. CONCLUSION: A prediction model based on multi-source data stored in a clinical data warehouse could accurately quantify rates of DRM. Automated detection using this statistical approach is feasible and could be applied to other nosocomial infections
Forest biodiversity, ecosystem functioning and the provision of ecosystem services
Forests are critical habitats for biodiversity and they are also essential for the provision of a wide range of ecosystem services that are important to human well-being. There is increasing evidence that biodiversity contributes to forest ecosystem functioning and the provision of ecosystem services. Here we provide a review of forest ecosystem services including biomass production, habitat provisioning services, pollination, seed dispersal, resistance to wind storms, fire regulation and mitigation, pest regulation of native and invading insects, carbon sequestration, and cultural ecosystem services, in relation to forest type, structure and diversity. We also consider relationships between forest biodiversity and multifunctionality, and trade-offs among ecosystem services. We compare the concepts of ecosystem processes, functions and services to clarify their definitions. Our review of published studies indicates a lack of empirical studies that establish quantitative and causal relationships between forest biodiversity and many important ecosystem services. The literature is highly skewed; studies on provisioning of nutrition and energy, and on cultural services, delivered by mixed-species forests are under-represented. Planted forests offer ample opportunity for optimising their composition and diversity because replanting after harvesting is a recurring process. Planting mixed-species forests should be given more consideration as they are likely to provide a wider range of ecosystem services within the forest and for adjacent land uses. This review also serves as the introduction to this special issue of Biodiversity and Conservation on various aspects of forest biodiversity and ecosystem services
A Multicenter, CrossâSectional Study on the Prevalence and Risk Factors for Nasal Colonization with Staphylococcus aureus
The spectral sensitivity of the acuity criterion: Effect of nonlinear summation of isolated parvocellular receptive field centers
Electron Bernstein waves driven by electron crescents near the electron diffusion region
Extracellular heat shock protein 70 (HSPA1A) and classical vascular risk factors in a general population
Atherosclerosis is a chronic inflammatory and autoimmune disease. Candidate molecules/autoantigens include heat shock proteins (HSPs); Hsp70 (HSPA1A) is one of the best studied HSPs. Various studies have shown a correlation between extracellular Hsp70 (eHsp70) and anti-Hsp70/anti-Hsp60 antibody concentration and development of atherosclerosis. A random sample of 456 people aged 40â60 (218 males, 234 females) was studied to investigate the prevalence of traditional vascular risk factors and eHsp70 and anti-Hsp70/anti-Hsp60 antibodies levels, according to the risk of vascular disease. Task Force Chart was applied for classification. Subjects were divided into three groups: G0 (with no vascular risk factor or a risk lower than 5%), nâ=â239; G1 (moderated 10â20% risk, who do not have established disease) nâ=â161; and G2 (established atherosclerosis disease) nâ=â52. eHsp70 and anti-Hsp70 were significantly lower in the atherosclerosis group (group 2) with respect to the other groups. Disease-free people showed the highest anti-Hsp60 concentration compared with the other two groups. A correlation has not been demonstrated between the concentrations of circulating Hsp70 (HSPA1A), anti-Hsp70, and anti-Hsp60 and classical vascular risk factors and C-reactive protein. Low levels of eHsp70 and anti-Hsp70 antibodies should be considered as candidate FRV. Simultaneous decrease of eHsp70 and anti-Hsp70 antibodies would be explained by circulating immune complex formation, and both could be proposed as biomarkers for the progression of atherosclerotic disease. Levels of circulating anti-Hsp60 antibodies may constitute a marker of inflammation in atherosclerosis