A survey on the blow up technique

The blow up technique is widely used in desingularization of degenerate singular points of planar vector fields. In this survey we give an overview of the different types of blow up and we illustrate them with many examples for better understanding. Moreover, we introduce a new generalization of the classical blow up.Preprin

A survey on the blow up technique

The blow up technique is widely used in desingularization of degenerate singular points of planar vector fields. In this survey we give an overview of the different types of blow up and we illustrate them with many examples for better understanding. Moreover, we introduce a new generalization of the classical blow up

Digging in the dark: the underground war on the Western Front in WWI

Throughout the First World War, with the trenches largely static, the combatants tried to break the deadlock by tunnelling under one another’s trenches. The Tunnelling Companies of the British Royal Engineers were engaged in a bitter struggle against German Pioneers that left both sides with heavy casualties. A project to determine the location of one particular act of heroism in that underground war has resulted in the erection of a monument to the Tunnellers at Givenchy-lès-la-Bassée in northern France

Screening and Brief Intervention for Alcohol Misuse in Older Adults: Training Outcomes Among Physicians and Other Healthcare Practitioners in Community-Based Settings

Screening and brief intervention (SBI) is increasingly available to older adults who engage in at-risk drinking. This study examined the extent to which SBI training influenced the willingness of healthcare providers in a community-based hospital and other clinical settings to promote the implementation of SBI. Ninety-three healthcare practitioners (primarily physicians, nurses, and social workers) who attended SBI training were asked about their intentions to apply the information in their professional practice, as well as their enthusiasm about recommending the training to others in their profession. Although there were no differences among the professions in terms of commitment to apply the information or level of comfort using the techniques, physicians were less interested in promoting SBI training among their colleagues. Although it may be more difficult to promote SBI in locations that don’t primarily provide mental health services, results suggest that primary care settings are precisely where training may be most useful

Lack of PAH emission toward low-mass embedded young stellar objects

PAHs have been detected toward molecular clouds and some young stars with disks, but have not yet been associated with embedded young stars. We present a sensitive mid-IR spectroscopic survey of PAH features toward a sample of low-mass embedded YSOs. The aim is to put constraints on the PAH abundance in the embedded phase of star formation using radiative transfer modeling. VLT-ISAAC L-band spectra for 39 sources and Spitzer IRS spectra for 53 sources are presented. Line intensities are compared to recent surveys of Herbig Ae/Be and T Tauri stars. The radiative transfer codes RADMC and RADICAL are used to model the PAH emission from embedded YSOs consisting of a PMS star with a circumstellar disk embedded in an envelope. The dependence of the PAH feature on PAH abundance, stellar radiation field, inclination and the extinction by the surrounding envelope is studied. The 3.3 micron PAH feature is undetected for the majority of the sample (97%), with typical upper limits of 5E-16 W/m^2. Compact 11.2 micron PAH emission is seen directly towards 1 out of the 53 Spitzer Short-High spectra, for a source that is borderline embedded. For all 12 sources with both VLT and Spitzer spectra, no PAH features are detected in either. In total, PAH features are detected toward at most 1 out of 63 (candidate) embedded protostars (<~ 2%), even lower than observed for class II T Tauri stars with disks (11-14%). Assuming typical class I stellar and envelope parameters, the absence of PAHs emission is most likely explained by the absence of emitting carriers through a PAH abundance at least an order of magnitude lower than in molecular clouds but similar to that found in disks. Thus, most PAHs likely enter the protoplanetary disks frozen out in icy layers on dust grains and/or in coagulated form.Comment: 13 pages, 9 figures, accepted for publication in A&