University College London

About: University College London is a education organization based out in London, United Kingdom. It is known for research contribution in the topics: Population & Context (language use). The organization has 81105 authors who have published 210603 publications receiving 9868552 citations. The organization is also known as: UCL & University College, London.

High-redshift star formation in the Hubble Deep Field revealed by a submillimetre-wavelength survey

Abstract: In the local Universe, most galaxies are dominated by stars, with less than ten per cent of their visible mass in the form of gas. Determining when most of these stars formed is one of the central issues of observational cosmology. Optical and ultraviolet observations of high-redshift galaxies (particularly those in the Hubble Deep Field) have been interpreted as indicating that the peak of star formation occurred between redshifts of 1 and 1.5. But it is known that star formation takes place in dense clouds, and is often hidden at optical wavelengths because of extinction by dust in the clouds. Here we report a deep submillimetre-wavelength survey of the Hubble Deep Field; these wavelengths trace directly the emission from dust that has been warmed by massive star-formation activity. The combined radiation of the five most significant detections accounts for 30–50 per cent of the previously unresolved background emission in this area. Four of these sources appear to be galaxies in the redshift range 2< z < 4, which, assuming these objects have properties comparable to local dust-enshrouded starburst galaxies, implies a star-formation rate during that period about a factor of five higher than that inferred from the optical and ultraviolet observations.

Maintenance Olaparib for Germline BRCA-Mutated Metastatic Pancreatic Cancer

Abstract: Background Patients with a germline BRCA1 or BRCA2 mutation make up a small subgroup of those with metastatic pancreatic cancer. The poly(adenosine diphosphate–ribose) polymerase (PARP) in...

IsoplotR: A free and open toolbox for geochronology

Abstract: This paper reviews the basic principles of radiometric geochronology as implemented in a new software package called IsoplotR, which was designed to be free, flexible and future-proof. IsoplotR is free because it is written in non-proprietary languages (R, Javascript and HTML) and is released under the GPL license. The program is flexible because its graphical user interface (GUI) is separated from the command line functionality, and because its code is completely open for inspection and modification. To increase future-proofness, the software is built on free and platform-independent foundations that adhere to international standards, have existed for several decades, and continue to grow in popularity. IsoplotR currently includes functions for U-Pb, Pb-Pb, 40 Ar/ 39 Ar, Rb-Sr, Sm-Nd, Lu-Hf, Re-Os, U-Th-He, fission track and U-series disequilibrium dating. It implements isochron regression in two and three dimensions, visualises multi-aliquot datasets as cumulative age distributions, kernel density estimates and radial plots, and calculates weighted mean ages using a modified Chauvenet outlier detection criterion that accounts for the analytical uncertainties in heteroscedastic datasets. Overdispersion of geochronological data with respect to these analytical uncertainties can be attributed to either a proportional underestimation of the analytical uncertainties, or to an additive geological scatter term. IsoplotR keeps track of error correlations of the isotopic ratio measurements within aliquots of the same samples. It uses a statistical framework that will allow it to handle error correlations between aliquots in the future. Other ongoing developments include the implementation of alternative user interfaces and the integration of IsoplotR with other data reduction software.

Evidence based cardiology: psychosocial factors in the aetiology and prognosis of coronary heart disease. Systematic review of prospective cohort studies.

Abstract: Do psychosocial factors cause coronary heart disease or affect survival among patients with coronary heart disease? Here we use an explicit methodological quality filter to review systematically the prospective cohort studies testing specific psychosocial hypotheses. This review of the epidemiological literature identifies the psychosocial factors that have been most rigorously tested. Only four psychosocial factors met the quality filter: type A/hostility, depression and anxiety, work characteristics, and social supports. The importance of other study designs—for example, ecological1 or nested case-control2–4 studies—is acknowledged. The review should be seen as complementary to existing reviews5–8 on single psychosocial factors and as a challenge to investigators in the field to ensure that the systematic review is made unbiased, kept up to date, and used to guide future hypothesis testing. #### Summary points In healthy populations, prospective cohort studies show a possible aetiological role for type A/hostility (6/14 studies), depression and anxiety (11/11 studies), psychosocial work characteristics (6/10 studies), social support (5/8 studies) In populations of patients with coronary heart disease, prospective studies show a prognostic role for depression and anxiety (6/6 studies), psychosocial work characteristics (1/2 studies), and social support (9/10 studies); none of five studies showed a prognostic role for type A/hostility Although this review can not discount the possibility of publication bias, prospective cohort studies provide strong evidence that psychosocial factors, particularly depression and social support, are independent aetiological and prognostic factors for coronary heart disease A psychosocial factor may be defined as a measurement that potentially relates psychological phenomena to the social environment and to pathophysiological changes. The validity and reliability (precision) of the questionnaire based instruments used to measure psychosocial factors has been improved through the use of psychometric techniques. By avoiding the unhelpful general term of “stress,” recent work has developed theoretical models—for example, the …

Progress in applications of magnetic nanoparticles in biomedicine

Abstract: A progress report is presented on a selection of scientific, technological and commercial advances in the biomedical applications of magnetic nanoparticles since 2003. Particular attention is paid to (i) magnetic actuation for in vitro non-viral transfection and tissue engineering and in vivo drug delivery and gene therapy, (ii) recent clinical results for magnetic hyperthermia treatments of brain and prostate cancer via direct injection, and continuing efforts to develop new agents suitable for targeted hyperthermia following intravenous injection and (iii) developments in medical sensing technologies involving a new generation of magnetic resonance imaging contrast agents, and the invention of magnetic particle imaging as a new modality. Ongoing prospects are also discussed.