1,403 research outputs found

    Imaging the transition between pre-planetary and planetary nebulae: : Integral Field Spectroscopy of hot post-AGB stars with NIFS

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    This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record [T. M. Gledhill, and K. P. Forde, 'Imaging the transition between pre-planetary and planetary nebulae: integral field spectroscopy of hot post-AGB stars with NIFS', MNRAS, Vol. 447 (2): 1080-1095, February 2015] is available online at: https://doi.org/10.1093/mnras/stu2493.We present 2 to 2.4 micron integral field spectroscopy of a sample of hot post-AGB stars with early-B spectral types, using the NIFS instrument on Gemini North. These stars are just beginning to ionize their immediate environments and turn into planetary nebulae (PNe).We use molecular hydrogen emission lines together with hydrogen and helium recombination lines to explore the distribution of molecular and atomic gas and the extent of the developing ionized region. We see a range of evolutionary stages: IRAS 18062+2410 and IRAS 18379-1707 have recently developed compact and unresolved regions of photoionized H within axisymmetric molecular envelopes, with the former object increasing its Br-Gamma flux by a factor of 5.3 in 14 years; IRAS 22023+5249 and IRAS 20462+3416 have extended Br-Gamma nebulae and in the latter object only weak H2 emission remains; IRAS 19336-0400 is at a more advanced stage of PN formation where H2 is mostly dissociated and we see structure in both the H and He recombination line nebulae. IRAS 19200+3457 is the only object not to show the He I line at 2.058 micron and is probably the least evolved object in our sample; the H2 emission forms a ring around the star and we suggest that this object may be a rare example of a "round" pre-PN in transition to a "round" PN.Peer reviewedFinal Accepted Versio

    Integral field spectroscopy of H-2 and CO emission in IRAS 18276-1431 : evidence for ongoing post-AGB mass-loss

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    The definitive version can be found at: http://www.wiley.com/ Copyright Wiley BlackwellWe present K-band integral field spectroscopy of the bipolar post-asymptotic giant branch (post-AGB) object IRAS 18276-1431 (OH 17.7-2.0) using SINFONI on the VLT. This allows us to image both the continuum and molecular features in this object from 1.95 to 2.45 mu m with a spatial resolution down to 70 mas and a spectral resolution of similar to 5000. We detect a range of H-2 rovibrational emission lines which are consistent with shock excitation in regions of dense (similar to 10(7) cm(-3)) gas with shock velocities in the range of 25-30 km s(-1). The distribution of H-2 emission in the bipolar lobes suggests that a fast wind is impinging on material in the cavity walls and tips. H-2 emission is also seen along a line of sight close to the obscured star as well as in the equatorial region to either side of the stellar position which has the appearance of a ring with radius 0.3 arcsec. This latter feature may be radially cospatial with the boundary between the AGB and post-AGB winds. The first overtone (CO)-C-12 bandheads are observed longward of 2.29 mu m with the v = 2-0 bandhead prominently in emission. The CO emission has the same spatial distribution as the K-band continuum and therefore originates from an unresolved central source close to the star. We interpret this as evidence for ongoing mass-loss in this object. This conclusion is further supported by a rising K-band continuum indicating the presence of warm dust close to the star, possibly down to the condensation radius. The redshifted scattered peak of the CO bandhead is used to estimate a dust velocity along the bipolar axis of 95 km s(-1) for the collimated wind. This places a lower limit of similar to 125 yr on the age of the bipolar cavities, meaning that the collimated fast wind turned on very soon after the cessation of AGB mass-loss.Peer reviewe

    Undergraduate teaching on biological weapons and bioterrorism at medical schools in the UK and the Republic of Ireland: results of a cross-sectional study

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    Objective To determine if individual undergraduate schools of medicine in the UK and the Republic of Ireland provide any teaching to medical students about biological weapons, bioterrorism, chemical weapons and weaponised radiation, if they perceive them to be relevant issues and if they figure them in their future plans. Design A cross-sectional study utilising an internet-based questionnaire sent to key figures responsible for leading on the planning and delivery of undergraduate medical teaching at all schools of medicine in the UK and Ireland. Setting All identified undergraduate schools of medicine in the UK and Ireland between August 2012 and December 2012. Outcome measures Numerical data and free text feedback about relevant aspects of undergraduate teaching. Results Of the 38 medical schools approached, 34 (28 in UK, 6 in Ireland) completed the questionnaire (89.47%). 4 (all in UK) chose not to complete it. 6/34 (17.65%) included some specific teaching on biological weapons and bioterrorism. 7/34 (20.59%) had staff with bioterrorism expertise (mainly in microbiological and syndromic aspects). 4/34 (11.76%) had plans to introduce some specific teaching on bioterrorism. Free text responses revealed that some felt that because key bodies (eg, UK's General Medical Council) did not request teaching on bioterrorism, then it should not be included, while others regarded this field of study as a postgraduate subject and not appropriate for undergraduates, or argued that the curriculum was too congested already. 4/34 (11.76%) included some specific teaching on chemical weapons, and 3/34 (8.82%) on weaponised radiation. Conclusions This study provides evidence that at the present time there is little teaching at the undergraduate level in the UK and Ireland on the subjects of biological weapons and bioterrorism, chemical weapons and weaponised radiation and signals that this situation is unlikely to change unless there were to be high-level policy guidance

    Multi-jet cross sections at NLO with BlackHat and Sherpa

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    In this talk, we report on a recent next-to-leading order QCD calculation of the production of a W boson in association with three jets at hadron colliders. The computation is performed by combining two programs, BlackHat for the computation of the virtual one-loop matrix elements and Sherpa for the real emission part.Comment: 4 pages, contribution to the proceedings of the XLIIIth Rencontres de Moriond (QCD

    Next-to-Leading Order Jet Physics with BlackHat

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    We present several results obtained using the BlackHat next-to-leading order QCD program library, in conjunction with SHERPA. In particular, we present distributions for vector boson plus 1,2,3-jet production at the Tevatron and at the asymptotic running energy of the Large Hadron Collider, including new Z+3-jet distributions. The Z+2-jet predictions for the second-jet P_T distribution are compared to CDF data. We present the jet-emission probability at NLO in W+2-jet events at the LHC, where the tagging jets are taken to be the ones furthest apart in pseudorapidity. We analyze further the large left-handed W polarization, identified in our previous study, for W bosons produced at high P_T at the LHC.Comment: Presented at RADCOR 2009 - 9th International Symposium on Radiative Corrections (Applications of Quantum Field Theory to Phenomenology), October 25 - 30 2009, Ascona, Switzerland}, 12 pages, 9 figures, LaTeX, v2 updated small correction to polarization effect plo

    Molecular mimicry of brucella melitensis epitopes in mouse and human arthritis

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    Brucellosis is one of the most frequent zoonosis worldwide. Infection is transferable to humans, where brucellosis is associated with high incidence of osteoarticular disease including osteomyelitis, arthritis and spondyloarthritis. Peripheral arthritis and sacroiliitis often develop in patients with no or low count of live Brucella. Recently, we demonstrated that mice develop spontaneous arthritis several weeks after acute infection when bacteria are already eradicated. We aim to decipher immune mechanism of the brucellosis-associated delayed arthritis that has not been elucidated so far
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