Are magnetic fields universal in O-type multiple systems?

Although significant progress has been achieved in recent surveys of the magnetism in massive stars, the origin of the detected magnetic fields remains to be the least understood topic in their studies. We present an analysis of 61 high-resolution spectropolarimetric observations of 36 systems with O-type primaries, among them ten known particle-accelerating colliding-wind binaries exhibiting synchrotron radio emission. Our sample consists of multiple systems with components at different evolutionary stages with wide and tight orbits and different types of interactions. For the treatment of the complex composite spectra of the multiple systems, we used a special procedure involving different line masks populated for each element separately. Out of the 36 systems, 22 exhibit in their LSD Stokes V profiles definitely detected Zeeman features, among them seven systems with colliding winds. For fourteen systems the detected Zeeman features are most likely associated with O-type components whereas for three systems we suggest an association with an early B-type component. For the remaining five systems the source of the field is unclear. Marginal evidence for the detection of a Zeeman feature is reported for eleven systems and non-detection for three systems. The large number of systems with definitely detected Zeeman features presents a mystery, but probably indicates that multiplicity plays a definite role in the generation of magnetic fields in massive stars. The newly found magnetic systems are supreme candidates for spectropolarimetric monitoring over their orbital and rotation periods to obtain trustworthy statistics on the magnetic field geometry and the distribution of field strength.Comment: 21 pages, 2 tables, 9 figures, accepted for publication in MNRA

Magnetic field geometry and chemical abundance distribution of the He-strong star CPD -57 3509

The magnetic field of CPD -57 3509 was recently detected in the framework of the BOB (B fields in OB stars) collaboration. We acquired low-resolution spectropolarimetric observations of CPD -57 3509 with FORS2 and high-resolution UVES observations randomly distributed over a few months to search for periodicity, to study the magnetic field geometry, and to determine the surface distribution of silicon and helium. We also obtained supplementary photometric observations at a timeline similar to the spectroscopic and spectropolarimetric observations. A period of 6.36d was detected in the measurements of the mean longitudinal magnetic field. A sinusoidal fit to our measurements allowed us to constrain the magnetic field geometry and estimate the dipole strength in the range of 3.9-4.5kG. Our application of the Doppler imaging technique revealed the presence of He I spots located around the magnetic poles, with a strong concentration at the positive pole and a weaker one around the negative pole. In contrast, high concentration Si III spots are located close to the magnetic equator. Further, our analysis of the spectral variability of CPD -57 3509 on short time scales indicates distinct changes in shape and position of line profiles possibly caused by the presence of beta Cep-like pulsations. A small periodic variability in line with the changes of the magnetic field strength is clearly seen in the photometric data.Comment: 11 pages, 5 tables, 7 figures, accepted for publication in MNRA

A Summary of the ADVANCE Trial

The publication of the U.K. Prospective Diabetes Study (UKPDS) in 1998 helped to shape the management of type 2 diabetes in recent years (1). The study demonstrated several points. First, sulfonylureas are as safe as insulin in controlling blood glucose. Second, metformin reduced cardiovascular disease in an overweight subgroup. Third, the same benefit of glycemic control in reducing microvascular disease (previously noted in type 1 diabetes) is applied equally to patients with type 2 diabetes. A separation in A1C of ∼1% in the UKPDS reduced the risk of microvascular disease (largely diabetic retinopathy) by ∼25%. This reflected the data from the Diabetes Control and Complications Trial, where a separation in A1C of 2% in intensive and standard groups led to a reduction in microvascular disease of ∼50% (2). A fourth demonstration was that there was no significant reduction in macrovascular disease but a trend toward fewer myocardial infarctions with more intensive glucose control. Fifth, using the current treatment of the time (first-generation sulfonylureas, human ultratard insulin, or metformin), it proved impossible to maintain glucose control, which tended to deteriorate throughout the study. It is now generally believed that the progressive fall in endogenous insulin production as β-cell numbers decline makes it difficult, if not impossible, to maintain tight control using standard treatment. Sixth, the UKPDS also showed that in those patients with hypertension, lowering blood pressure (BP) to moderate levels with either captopril or atenolol could reduce microvascular disease (3). In a subsequent study, the UKPDS investigators presented the rates of both micro- and macrovascular disease according to the achieved levels of A1C during the study (4). They showed a linear relationship between A1C and both groups of complications. The implication of the article was that if glycemic control could be tightened below the levels achieved in the UKPDS, then it might be possible to reduce rates, not only of microvascular complications, but also cardiovascular disease as well. The aim of the glucose arm of the Action in Diabetes and Vascular Disease: Preterax and Diamicron MR Controlled Evaluation (ADVANCE) trial (5) was to build on the information gained by the UKPDS and to answer the question as to whether intensifying glucose control to achieve an A1C of <6.5% would provide additional benefit in reducing the risk of both micro- and macrovascular disease. ADVANCE also asked questions about BP lowering in patients with type 2 diabetes. The aims of the BP arm were to establish whether routine provision of BP-lowering therapy produced additional benefits in terms of macro- and microvascular disease, irrespective of baseline BP, and added to the benefits produced by other cardiovascular preventive therapies, including ACE inhibitors

Extreme Technicolor & The Walking Critical Temperature

We map the phase diagram of gauge theories of fundamental interactions in the flavor-temperature plane using chiral perturbation theory to estimate the relation between the pion decaying constant and the critical temperature above which chiral symmetry is restored. We then investigate the impact of our results on models of dynamical electroweak symmetry breaking and therefore on the electroweak early universe phase transition.Comment: RevTeX, 18 pages, 3 figure

Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation

In this paper we present the first identification of foreshock cavitons and the formation of spontaneous hot flow anomalies (SHFAs) with the Vlasiator global magnetospheric hybrid-Vlasov simulation code. In agreement with previous studies we show that cavitons evolve into SHFAs. In the presented run, this occurs very near the bow shock. We report on SHFAs surviving the shock crossing into the down-stream region and show that the interaction of SHFAs with the bow shock can lead to the formation of a magnetosheath cavity, previously identified in observations and simulations. We report on the first identification of long-term local weakening and erosion of the bow shock, associated with a region of increased foreshock SHFA and caviton formation, and repeated shock crossings by them. We show that SHFAs are linked to an increase in suprathermal particle pitch-angle spreads. The realistic length scales in our simulation allow us to present a statistical study of global caviton and SHFA size distributions, and their comparable size distributions support the theory that SHFAs are formed from cavitons. Virtual spacecraft observations are shown to be in good agreement with observational studies.Peer reviewe

Deep Vascular Imaging in Wounds by Two-Photon Fluorescence Microscopy

Deep imaging within tissue (over 300 mu m) at micrometer resolution has become possible with the advent of two-photon fluorescence microscopy (2PFM). The advantages of 2PFM have been used to interrogate endogenous and exogenous fluorophores in the skin. Herein, we employed the integrin (cell-adhesion proteins expressed by invading angiogenic blood vessels) targeting characteristics of a two-photon absorbing fluorescent probe to image new vasculature and fibroblasts up to approximate to 1600 mu m within wound (neodermis)/granulation tissue in lesions made on the skin of mice. Reconstruction revealed three dimensional (3D) architecture of the vascular plexus forming at the regenerating wound tissue and the presence of a fibroblast bed surrounding the capillaries. Biologically crucial events, such as angiogenesis for wound healing, may be illustrated and analyzed in 3D on the whole organ level, providing novel tools for biomedical applications

On the incompleteness of the historical record of North Atlantic tropical cyclones

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 35 (2008): L11803, doi:10.1029/2008GL033546.There is some question as to whether the historical record of observed North Atlantic tropical cyclones prior to the advent of satellite coverage is complete. This question is central to understanding the historical trend in tropical cyclone activity and the effect of environmental factors on it. To address this question, a statistical model of the relationship between annual cyclone counts between 1870 and 2004 and sea surface temperature and the state of the Southern Oscillation is extended to allow for non-decreasing observation probability prior to 1966. The estimated observation probabilities increase from 0.72 in 1870 to 1 in 1964. Allowing for record incompleteness reduces the estimated effect of sea surface temperature on annual tropical cyclone activity.This work was supported by NOAA Grant NA17RJ1223