A physical approach to modelling large-scale galactic magnetic fields

A convenient representation of the structure of the large-scale galactic magnetic field is required for the interpretation of polarization data in the sub-mm and radio ranges, in both the Milky Way and external galaxies. We develop a simple and flexible approach to construct parametrised models of the large-scale magnetic field of the Milky Way and other disc galaxies, based on physically justifiable models of magnetic field structure. The resulting models are designed to be optimised against available observational data. Representations for the large-scale magnetic fields in the flared disc and spherical halo of a disc galaxy were obtained in the form of series expansions whose coefficients can be calculated from observable or theoretically known galactic properties. The functional basis for the expansions is derived as eigenfunctions of the mean-field dynamo equation or of the vectorial magnetic diffusion equation. The solutions presented are axially symmetric but the approach can be extended straightforwardly to non-axisymmetric cases. The magnetic fields are solenoidal by construction, can be helical, and are parametrised in terms of observable properties of the host object, such as the rotation curve and the shape of the gaseous disc. The magnetic field in the disc can have a prescribed number of field reversals at any specified radii. Both the disc and halo magnetic fields can separately have either dipolar or quadrupolar symmetry. The model is implemented as a publicly available software package GalMag which allows, in particular, the computation of the synchrotron emission and Faraday rotation produced by the model's magnetic field. The model can be used in interpretations of observations of magnetic fields in the Milky Way and other spiral galaxies, in particular as a prior in Bayesian analyses. (Abridged.)Comment: 20 pages, 14 figures. Accepted for publication in A&

Bioinformatics tools in predictive ecology: Applications to fisheries

This article is made available throught the Brunel Open Access Publishing Fund - Copygith @ 2012 Tucker et al.There has been a huge effort in the advancement of analytical techniques for molecular biological data over the past decade. This has led to many novel algorithms that are specialized to deal with data associated with biological phenomena, such as gene expression and protein interactions. In contrast, ecological data analysis has remained focused to some degree on off-the-shelf statistical techniques though this is starting to change with the adoption of state-of-the-art methods, where few assumptions can be made about the data and a more explorative approach is required, for example, through the use of Bayesian networks. In this paper, some novel bioinformatics tools for microarray data are discussed along with their ‘crossover potential’ with an application to fisheries data. In particular, a focus is made on the development of models that identify functionally equivalent species in different fish communities with the aim of predicting functional collapse

Resolving the complete genome of Kuenenia stuttgartiensis from a membrane bioreactor enrichment using Single-Molecule Real-Time sequencing

Contains fulltext : 190074.pdf (publisher's version ) (Open Access)10 p

In vitro effect of nanosilver toxicity on fibroblast and mesenchymal stem cell lines

Nanotechnology presents countless opportunities to develop new and improved consumer products for the benefit of the society . A most prominent nanoproduct is nanosilver. Nanosilver particles are generally smaller than 100 nm and contain 20–15,000 silver atoms. Despite the wide application of nanomaterials, there is a serious lack of information concerning their impact on human health. In the previous study we reported the cytotoxic of nanosilver on osteoblast G292 cancer cell line and the amount of IC50 determined as 3.42 µg/ml (Moaddab et al., Iran. Nano Lett., Vol. 1, No. 1, January 2011, pp. 11-16). The purpose of the present study is to assess the biological assay of nanosilver on two normal cell lines of fibroblast (HF2), and mesenchymal stem cells . The effect of nanosilver on these cells is evaluated by light microscopy, and by cell proliferation and standard cytotoxicity assays. The results demonstrate a concentration-dependent toxicity for the cells tested, and IC50 was determined as 6.33, and 6.68 µg/ml in mesenchymal stem cell, and fibroblast HF2, respectively. There is no significant difference between the 24 h and 48 h of cells exposure to nanosilver. The results show that Nano-Ag possesses low toxicity to normal cells and can display potential application in cancer chemoprevention and chemotherapy

Impact of antibiotic timing on mortality from Gram-negative bacteraemia in an English district general hospital: the importance of getting it right every time

Objectives: There is limited evidence that empirical antimicrobials affect patient-oriented outcomes in Gram-negative bacteraemia. We aimed to establish the impact of effective antibiotics at four consecutive timepoints on 30 day all-cause mortality and length of stay in hospital. / Methods: We performed a multivariable survival analysis on 789 patients with Escherichia coli, Klebsiella spp. and Pseudomonas aeruginosa bacteraemias. Antibiotic choices at the time of the blood culture (BC), the time of medical clerking and 24 and 48 h post-BC were reviewed. / Results: Patients that received ineffective empirical antibiotics at the time of the BC had higher risk of mortality before 30 days (HR = 1.68, 95% CI = 1.19–2.38, P = 0.004). Mortality was higher if an ineffective antimicrobial was continued by the clerking doctor (HR = 2.73, 95% CI = 1.58–4.73, P < 0.001) or at 24 h from the BC (HR = 1.83, 95% CI = 1.05–3.20, P = 0.033) when compared with patients who received effective therapy throughout. Hospital-onset infections, ‘high inoculum’ infections and elevated C-reactive protein, lactate and Charlson comorbidity index were independent predictors of mortality. Effective initial antibiotics did not statistically significantly reduce length of stay in hospital (−2.98 days, 95% CI = −6.08–0.11, P = 0.058). The primary reasons for incorrect treatment were in vitro antimicrobial resistance (48.6%), initial misdiagnosis of infection source (22.7%) and non-adherence to hospital guidelines (15.7%). / Conclusions: Consecutive prescribing decisions affect mortality from Gram-negative bacteraemia

Long-term outcome and risk factors for late mortality in Gram-negative bacteraemia: a retrospective cohort study

OBJECTIVES: The long-term outcomes of patients following Gram-negative bacteraemia (GNB) are poorly understood. We describe a cohort of patients with GNB over a two-year period and determine factors associated with late mortality (death between days 31 and 365 after detection of bacteraemia). METHODS: This is a single center retrospective observational cohort study of 789 patients with confirmed Escherichia coli, Klebsiella spp and Pseudomonas aeruginosa bacteraemias with a follow-up of one year. Multivariable survival analysis was used to determine the risk factors for late mortality in patients who survived the initial 30-day period of infection. RESULTS: Overall, one-year all-cause mortality was 36.2%, with 18.1% of patients dying within 30 days and 18.1% of patients suffering late mortality. An adverse antimicrobial resistance profile (HR 1.095 per any additional antimicrobial category, 95% CI 1.018 - 1.178, p = 0.014) and infection with Pseudomonas aeruginosa (HR 2.08, 95% CI 1.11 - 3.88, p = 0.022) were independent predictors of late mortality. Other significant factors included the Charlson Comorbidity Index and hospitalization length after the index blood culture. CONCLUSION: Patients with GNB have a poor long-term prognosis. Risk factors for greater mortality at one year include comorbidity, hospitalization length, the infecting organism, and its resistance profile