Collisions and Mergers of Disk Galaxies: Hydrodynamics of Star Forming Gas

We summarize the results of numerical simulations of colliding gas-rich disk galaxies in which the impact velocity is set parallel to the spin axes of the two galaxies. The effects of varying the impact speed are studied with particular attention to the resulting gaseous structures and shockwave patterns, and the time needed to produce these structures. The simulations employ an N-body treatment of the stars and dark matter, together with an SPH treatment of the gas, in which all components of the models are gravitationally active. The results indicate that for such impact geometries, collisions can lead to the very rapid formation of a central, rapidly rotating, dense gas disk, and that in all cases extensive star formation is predicted by the very high gas densities and prevalence of shocks, both in the nucleus and out in the galactic disks. As the dense nucleus is forming, gas and stars are dispersed over very large volumes, and only fall back towards the nucleus over long times. In the case of low impact velocities, this takes an order of magnitude more time than that needed for the formation of a dense nucleus.Comment: To be published in Proceedings of 'The Evolution of Galaxies III- From simple approaches to self-consistent models,' held in Kiel, Germany, July 2002, Astrophysics and Space Science (Kluwer), vol. 284, p. 479, 200

Detection of Massive Forming Galaxies at Redshifts Greater than One

The complex problem of when and how galaxies formed has not until recently been susceptible of direct attack. It has been known for some time that the excessive number of blue galaxies counted at faint magnitudes implies that a considerable fraction of the massive star formation in the universe occurred at z < 3, but, surprisingly, spectroscopic studies of galaxies down to a B magnitude of 24 found little sign of the expected high-z progenitors of current massive galaxies, but rather, in large part, small blue galaxies at modest redshifts z \sim 0.3. This unexpected population has diverted attention from the possibility that early massive star-forming galaxies might also be found in the faint blue excess. From KECK spectroscopic observations deep enough to encompass a large population of z > 1 field galaxies, we can now show directly that in fact these forming galaxies are present in substantial numbers at B \sim 24, and that the era from redshifts 1 to 2 was clearly a major period of galaxy formation. These z > 1 galaxies have very unusual morphologies as seen in deep HST WFPC2 images.Comment: 10 pages LaTeX + 5 PostScript figures in uuencoded gzipped tar file; aasms4.sty, flushrt.sty, overcite.sty (the two aastex4.0 and overcite.sty macros are available from xxx.lanl.gov) Also available (along with style files) via anonymous ftp to ftp://hubble.ifa.hawaii.edu/pub/preprints . E-print version of paper adds citation cross-references to other archived e-prints, where available. To appear in Nature October 19, 199

Gaps and Overlaps in Cancer Multidisciplinary Team Communication: Analysis of Speech

Funder: Health Services and Delivery Research Programme; FundRef: https://doi.org/10.13039/501100002001 Guided by the principles of conversation analysis, we examined the communication practices used to negotiate levels of participation in cancer multidisciplinary team meetings and their implications for patient safety. Three cancer teams participated. Thirty-six weekly meetings were video recorded, encompassing 822 case reviews. A cross-section was transcribed using Jefferson notation. We found a low frequency of gaps between speakers (3%), high frequency of overlaps (24%), and no-gaps-no-overlaps (73%), suggesting fast turn transitions. Securing a turn to speak is challenging due to a systematic reduction in turn-taking opportunities. We contribute to group research with the development of a microlevel methodology for studying multidisciplinary teams. </jats:p

Searching for Exoplanets Using a Microresonator Astrocomb

Detection of weak radial velocity shifts of host stars induced by orbiting planets is an important technique for discovering and characterizing planets beyond our solar system. Optical frequency combs enable calibration of stellar radial velocity shifts at levels required for detection of Earth analogs. A new chip-based device, the Kerr soliton microcomb, has properties ideal for ubiquitous application outside the lab and even in future space-borne instruments. Moreover, microcomb spectra are ideally suited for astronomical spectrograph calibration and eliminate filtering steps required by conventional mode-locked-laser frequency combs. Here, for the calibration of astronomical spectrographs, we demonstrate an atomic/molecular line-referenced, near-infrared soliton microcomb. Efforts to search for the known exoplanet HD 187123b were conducted at the Keck-II telescope as a first in-the-field demonstration of microcombs

Exploring the Ecological History of a Tropical Agroforestry Landscape Using Fossil Pollen and Charcoal Analysis from Four Sites in Western Ghats, India

Contrary to expectations, some human-modified landscapes are considered to sustain both human activities and biodiversity over the long-term. Agroforestry systems are among these landscapes where crops are planted under native shade trees. In this context, ancient agroforestry systems can provide insight into how farmers managed the landscape over time. Such insight can help to quantify the extent to which tropical forests (especially habitat-specialist trees) are responding to local and landscape-level management. Here, we extracted fossil pollen (indicator of past vegetation changes) and macroscopic charcoal (indicator of biomass burning) from four forest hollows’ sedimentary sequences in an ancient agroforestry system in Western Ghats, India. We used a mixed-modelling approach and a principal components analysis (PCA) to determine past trajectories of forest change and species composition dynamics for the last 900 years. In addition, we reconstructed the long-term forest canopy dynamics and examined the persistence of habitat-specialist trees over time. Our results show that the four sites diverged to a surprising degree in both taxa composition and dynamics. However, despite these differences, forest has persisted over 900 years under agricultural activities within agroforestry systems. This long-term analysis highlights the importance of different land-use legacies as a framework to increase the effectiveness of management across tropical agricultural lands

Crisis resolution and home treatment in the UK: A survey of model fidelity using a novel review methodology

Crisis resolution teams (CRTs) provide treatment at home to people experiencing mental health crises, as an alternative to hospital admission. Previous UK research, based on self‐report surveys, suggests that a loosely specified model has resulted in wide variations in CRTs’ service delivery, organization and outcomes. A fidelity scale (developed through evidence review and stakeholder consensus) provided a means of objectively measuring adherence to a model of good practice for CRTs, via one‐day fidelity reviews of UK crisis teams. Reviews included interviews with service users, carers, staff and managers, and examination of data, policies, protocols and anonymized case notes. Of the 75 teams reviewed, 49 (65%) were assessed as being moderate fidelity and the rest as low fidelity, with no team achieving high fidelity. The median score was 122 (range: 73–151; inter‐quartile range: 111–132). Teams achieved higher scores on items about structure and organization, for example ease of referral, medication and safety systems, but scored poorly on items about the content of care and interventions. Despite a national mandate to implement the CRT model, there are wide variations in implementation in the UK and no teams in our sample achieved overall high fidelity. This suggests that a mandatory national policy is not in itself sufficient to achieve good quality implementation of a service model. The CRT Fidelity Scale provides a feasible and acceptable means to objectively assess model fidelity in CRTs. There is a need for development and testing of interventions to enhance model fidelity and facilitate improvements to these services

Matrix and Tensor Factorization Methods for Toxicogenomic Modeling and Prediction

Peer reviewe

Integrating isotopes and documentary evidence : dietary patterns in a late medieval and early modern mining community, Sweden

We would like to thank the Archaeological Research Laboratory, Stockholm University, Sweden and the Tandem Laboratory (Ångström Laboratory), Uppsala University, Sweden, for undertaking the analyses of stable nitrogen and carbon isotopes in both human and animal collagen samples. Also, thanks to Elin Ahlin Sundman for providing the δ13C and δ15N values for animal references from Västerås. This research (Bäckström’s PhD employment at Lund University, Sweden) was supported by the Berit Wallenberg Foundation (BWS 2010.0176) and Jakob and Johan Söderberg’s foundation. The ‘Sala project’ (excavations and analyses) has been funded by Riksens Clenodium, Jernkontoret, Birgit and Gad Rausing’s Foundation, SAU’s Research Foundation, the Royal Physiographic Society of Lund, Berit Wallenbergs Foundation, Åke Wibergs Foundation, Lars Hiertas Memory, Helge Ax:son Johnson’s Foundation and The Royal Swedish Academy of Sciences.Peer reviewedPublisher PD

Antiferromagnetic-ferromagnetic phase domain development in nanopatterned FeRh islands

The antiferromagnetic-to-ferromagnetic phase transition in B2-ordered FeRh is imaged in laterally confined nanopatterned islands using photoemission electron microscopy with x-ray magnetic circular dichroism contrast. The resulting magnetic images directly detail the progression in the shape and size of the FM phase domains during heating and cooling through the transition. In 5-μm-square islands this domain development during heating is shown to proceed in three distinct modes—nucleation, growth, and merging—each with subsequently greater energy costs. In 0.5-μm islands, which are smaller than the typical final domain size, the growth mode is stunted and the transition temperature is found to be reduced by 20 K. The modification to the transition temperature is found by high-resolution scanning transmission electron microscopy to be due to a 100-nm chemically disordered edge grain present as a result of ion implantation damage during the patterning. FeRh has unique possibilities for magnetic memory applications; the inevitable changes to its magnetic properties due to subtractive nanofabrication will need to be addressed in future work in order to progress from sheet films to suitable patterned devices