Diffuse continuum gamma rays from the Galaxy

A new study of the diffuse Galactic gamma-ray continuum radiation is presented, using a cosmic-ray propagation model which includes nucleons, antiprotons, electrons, positrons, and synchrotron radiation. Our treatment of the inverse Compton (IC) scattering includes the effect of anisotropic scattering in the Galactic interstellar radiation field (ISRF) and a new evaluation of the ISRF itself. Models based on locally measured electron and nucleon spectra and synchrotron constraints are consistent with gamma-ray measurements in the 30-500 MeV range, but outside this range excesses are apparent. A harder nucleon spectrum is considered but fitting to gamma rays causes it to violate limits from positrons and antiprotons. A harder interstellar electron spectrum allows the gamma-ray spectrum to be fitted above 1 GeV as well, and this can be further improved when combined with a modified nucleon spectrum which still respects the limits imposed by antiprotons and positrons. A large electron/IC halo is proposed which reproduces well the high-latitude variation of gamma-ray emission. The halo contribution of Galactic emission to the high-latitude gamma-ray intensity is large, with implications for the study of the diffuse extragalactic component and signatures of dark matter. The constraints provided by the radio synchrotron spectral index do not allow all of the <30 MeV gamma-ray emission to be explained in terms of a steep electron spectrum unless this takes the form of a sharp upturn below 200 MeV. This leads us to prefer a source population as the origin of the excess low-energy gamma rays.Comment: Final version accepted for publication in The Astrophysical Journal (vol. 537, July 10, 2000 issue); Many Updates; 20 pages including 49 ps-figures, uses emulateapj.sty. More details can be found at http://www.gamma.mpe-garching.mpg.de/~aws/aws.htm

Propagation of cosmic-ray nucleons in the Galaxy

We describe a method for the numerical computation of the propagation of primary and secondary nucleons, primary electrons, and secondary positrons and electrons. Fragmentation and energy losses are computed using realistic distributions for the interstellar gas and radiation fields, and diffusive reacceleration is also incorporated. The models are adjusted to agree with the observed cosmic-ray B/C and 10Be/9Be ratios. Models with diffusion and convection do not account well for the observed energy dependence of B/C, while models with reacceleration reproduce this easily. The height of the halo propagation region is determined, using recent 10Be/9Be measurements, as >4 kpc for diffusion/convection models and 4-12 kpc for reacceleration models. For convection models we set an upper limit on the velocity gradient of dV/dz < 7 km/s/kpc. The radial distribution of cosmic-ray sources required is broader than current estimates of the SNR distribution for all halo sizes. Full details of the numerical method used to solve the cosmic-ray propagation equation are given.Comment: 15 pages including 23 ps-figures and 3 tables, latex2e, uses emulateapj.sty (ver. of 11 May 1998, enclosed), apjfonts.sty, timesfonts.sty. To be published in ApJ 1998, v.509 (December 10 issue). More details can be found at http://www.gamma.mpe-garching.mpg.de/~aws/aws.html Some references are correcte

Positrons from particle dark-matter annihilation in the Galactic halo: propagation Green's functions

We have made a calculation of the propagation of positrons from dark-matter particle annihilation in the Galactic halo in different models of the dark matter halo distribution using our 3D code, and present fits to our numerical propagation Green's functions. We show that the Green's functions are not very sensitive to the dark matter distribution for the same local dark matter energy density. We compare our predictions with computed cosmic ray positron spectra (``background'') for the ``conventional'' CR nucleon spectrum which matches the local measurements, and a modified spectrum which respects the limits imposed by measurements of diffuse Galactic gamma-rays, antiprotons, and positrons. We conclude that significant detection of a dark matter signal requires favourable conditions and precise measurements unless the dark matter is clumpy which would produce a stronger signal. Although our conclusion qualitatively agrees with that of previous authors, it is based on a more realistic model of particle propagation and thus reduces the scope for future speculations. Reliable background evaluation requires new accurate positron measurements and further developments in modelling production and propagation of cosmic ray species in the Galaxy.Comment: 8 pages, 6 ps-figures, 3 tables, uses revtex. Accepted for publication in Physical Review D. More details can be found at http://www.gamma.mpe-garching.mpg.de/~aws/aws.htm

Completion gastrectomy with esophagojejunostomy for management of complications of benign foregut surgery

Background: With the worldwide epidemic of obesity, an increasing number of bariatric operations and antireflux fundoplications are being performed. Despite low morbidity of the primary foregut surgery, completion gastrectomy may be necessary as a definitive procedure for complications of prior foregut surgery; however, the literature evaluating outcomes after completion gastrectomy with esophagojejunostomy (EJ) for benign diseases is limited. We present our experience of completion gastrectomy with Roux-en-Y EJ in the setting of benign disease at a single tertiary center. Methods and Procedures: All patients who underwent total, proximal, or completion gastrectomy with EJ for complications of benign foregut surgery from January 2006 to December 2015 were retrospectively identified. All cancer operations were excluded. Results: There were 23 patients who underwent gastrectomy with EJ (13 laparoscopic EJ [LEJ] and 10 open EJ). The index operations included 12 antireflux, 9 bariatric, and 2 peptic ulcer disease surgeries. Seventy-eight percent of patients had surgical or endoscopic interventions before EJ, with a median of one prior intervention and a median interval from the index operation to EJ of 25 months (interquartile range 9–87). The 30-day perioperative complication rate was 30% with 17% classified being major (Clavien–Dindo ≥ III) and no 30-day perioperative mortality. Comparing laparoscopic and open approaches showed similar operative times, estimated blood loss, and overall complication rate. LEJ was associated with a shorter length of stay (LOS) (P < .001), fewer postoperative ICU days (P = .002), fewer 6-month complication rates (P < .007), and decreased readmission rate (P = .024). Conclusion: Our series demonstrates that EJ is a reasonable option for reoperative foregut surgery. The laparoscopic approach appears to be associated with decreased LOS and readmissions

Surgical ward rounds in England: a trainee-led multi-centre study of current practice

BACKGROUND: Recent guidance advocates daily consultant-led ward rounds, conducted in the morning with the presence of senior nursing staff and minimising patients on outlying wards. These recommendations aim to improve patient management through timely investigations, treatment and discharge. This study sought to evaluate the current surgical ward round practices in England. METHODS: Information regarding timing and staffing levels of surgical ward rounds was collected prospectively over a one-week period. The location of each patient was also documented. Two surgical trainee research collaboratives coordinated data collection from 19 hospitals and 13 surgical subspecialties. RESULTS: Data from 471 ward rounds involving 5622 patient encounters was obtained. 367 (77.9%) ward rounds commenced before 9am. Of 422 weekday rounds, 190 (45%) were consultant-led compared with 33 of the 49 (67%) weekend rounds. 2474 (44%) patients were seen with a nurse present. 1518 patients (27%) were classified as outliers, with 361 ward rounds (67%) reporting at least one outlying patient. CONCLUSION: Recommendations for daily consultant-led multi disciplinary ward rounds are poorly implemented in surgical practice, and patients continue to be managed on outlying wards. Although strategies may be employed to improve nursing attendance on ward rounds, substantial changes to workforce planning would be required to deliver daily consultant-led care. An increasing political focus on patient outcomes at weekends may prompt changes in these areas

Gas Dynamics in the LINER Galaxy NGC 5005: Episodic Fueling of a Nuclear Disk

We report high-resolution CO(1-0) observations in the central 6 kpc of the LINER galaxy NGC 5005 with the Owens Valley Radio Observatory millimeter array. Molecular gas is distributed in three components - a ring at a radius of about 3 kpc, a strong central condensation, and a stream to the northwest of the nucleus but inside the 3 kpc ring. The central condensation is a disk of about 1 kpc radius with a molecular gas mass of 2 x 10^9 M_sun. The stream between the 3 kpc ring and the nuclear disk lies on a straight dust lane seen in the optical. If this material moves in the plane of the galaxy, it has a velocity offset by up to ~ 150 km/s from galactic rotation. We suggest that an optically inconspicuous stellar bar lying within the 3 kpc ring can explain the observed gas dynamics. This bar is expected to connect the nuclear disk and the ring along the position angle of the northwest stream. A position-velocity cut in this direction reveals features which match the characteristic motions of gas in a barred potential. Our model indicates that gas in the northwest stream is on an x_1 orbit at the bar's leading edge; it is falling into the nucleus with a large noncircular velocity, and will eventually contribute about 2 x 10^8 M_sun to the nuclear disk. If most of this material merges with the disk on its first passage of pericenter, the gas accretion rate during the collision will be 50 M_sun/yr. We associate the nuclear disk with an inner 2:1 Lindblad resonance, and the 3 kpc ring with an inner 4:1 Lindblad resonance. The high rate of bar-driven inflow and the irregular appearance of the northwest stream suggest that a major fueling event is in progress in NGC 5005. Such episodic (rather than continuous) gas supply can regulate the triggering of starburst and accretion activity in galactic nuclei. (abridged)Comment: 26 pages, 12 figures, AASTeX, ApJ in press (Feb. 10, 2000). For full-resolution figures, see http://www.ovro.caltech.edu/mm/science/science.htm

Radioactive 26Al and massive stars in the Galaxy

Gamma-rays from radioactive 26Al (half life ~7.2 10^5 yr) provide a 'snapshot' view of ongoing nucleosynthesis in the Galaxy. The Galaxy is relatively transparent to such gamma-rays, and emission has been found concentrated along the plane of the Galaxy. This led to the conclusion1 that massive stars throughout the Galaxy dominate the production of 26Al. On the other hand, meteoritic data show locally-produced 26Al, perhaps from spallation reactions in the protosolar disk. Furthermore, prominent gamma-ray emission from the Cygnus region suggests that a substantial fraction of Galactic 26Al could originate in localized star-forming regions. Here we report high spectral resolution measurements of 26Al emission at 1808.65 keV, which demonstrate that the 26Al source regions corotate with the Galaxy, supporting its Galaxy-wide origin. We determine a present-day equilibrium mass of 2.8 (+/-0.8) M_sol of 26Al. We use this to estimate that the frequency of core collapse (i.e. type Ib/c and type II) supernovae to be 1.9(+/- 1.1) events per century.Comment: accepted for publication in Nature, 24 pages including Online Supplements, 11 figures, 1 tabl

Adjustments to warfarin dosing after gastric bypass and sleeve gastrectomy

Background: Warfarin dosing after bariatric surgery may be influenced by alterations in gastrointestinal pH, transit time, absorptive surface area, gut microbiota, food intake, and adipose tissue. Objectives: The aim of this study was to describe trends in warfarin dosing after Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG). Setting: Single academic center. Methods: All patients chronically on warfarin anticoagulation before RYGB or SG were retrospectively identified. Indications for anticoagulation, history of bleeding or thrombotic events, perioperative complications, and warfarin dosing were collected. Results: Fifty-three patients (RYGB n = 31, SG n = 22) on chronic warfarin therapy were identified (56.6% female, mean 54.4 ± 11.7 yr of age). Of this cohort, 34.0% had prior venous thromboembolic events, 43.4% had atrial fibrillation, and 5.7% had mechanical cardiac valves. Preoperatively, the average daily dose of warfarin was similar in the RYGB group (8.3 ± 4.1 mg) and SG group (6.9 ± 2.8 mg). One month after surgery, mean daily dose of warfarin was reduced 24.1% in the RYGB group (P<.001) and 23.2% in the SG group (P = .002). At 12 months postoperatively, the required daily warfarin dose compared with baseline remained statistically different (RYGB: 6.8 ± 3.8 mg; SG: 6.1 ± 2.0 mg). Conclusions: The warfarin dose is expected to be decreased by approximately 25% from preoperative levels after both RYGB and SG. Lower dose requirement within the first month after bariatric surgery is followed by a trend toward increased warfarin dose requirements, but remain less than baseline. Because dose requirements change constantly over time, frequent postoperative monitoring of the international normalized ratio is recommended

Comparative outcomes of bariatric surgery in patients with impaired mobility and ambulatory population

Purpose: This study aims to characterize complications, metabolic improvement, and change in ambulation status for patients with impaired mobility undergoing bariatric surgery. Material and methods: Individuals undergoing primary sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) from February 2008 to December 2015 were included. Impaired mobility (WC) was defined as using a wheelchair or motorized scooter for at least part of a typical day. The WC group was propensity score matched to ambulatory patients (1:5 ratio). Comparisons were made for 30-day morbidity and mortality and 1-year improvement in weight-related comorbidities. Results: There were 93 patients in the WC group matched to 465 ambulatory controls. The median operative time (180 vs 159 min, p = 0.003) and postoperative length of stay (4 vs 3 days, p ≤ 0.001) was higher in the WC group. There were no differences in readmission or all-cause morbidity within 30 days. The median percent excess weight loss (%EWL) at 1 year was similar (WC group, 65% available, 53% EWL vs AMB group, 73% available, 54% EWL); however, patients with impaired mobility were less likely to experience improvement in diabetes (76 vs 90%, p = 0.046), hypertension (63 vs 82%, p < 0.005), and obstructive sleep apnea (53 vs 71%, p < 0.001). Within the WC group, 62% had improvement in their mobility status, eliminating dependence on wheelchair or scooter assistance. Conclusion: Patients with both obesity and impaired mobility experience similar rates of perioperative morbidity and weight loss at 1 year compared to ambulatory controls. However, improvement in weight-related comorbidities may be less likely with impaired mobility

The distribution of pond snail communities across a landscape: separating out the influence of spatial position from local habitat quality for ponds in south-east Northumberland, UK

Ponds support a rich biodiversity because the heterogeneity of individual ponds creates, at the landscape scale, a diversity of habitats for wildlife. The distribution of pond animals and plants will be influenced by both the local conditions within a pond and the spatial distribution of ponds across the landscape. Separating out the local from the spatial is difficult because the two are often linked. Pond snails are likely to be affected by both local conditions, e.g. water hardness, and spatial patterns, e.g. distance between ponds, but studies of snail communities struggle distinguishing between the two. In this study, communities of snails were recorded from 52 ponds in a biogeographically coherent landscape in north-east England. The distribution of snail communities was compared to local environments characterised by the macrophyte communities within each pond and to the spatial pattern of ponds throughout the landscape. Mantel tests were used to partial out the local versus the landscape respective influences. Snail communities became more similar in ponds that were closer together and in ponds with similar macrophyte communities as both the local and the landscape scale were important for this group of animals. Data were collected from several types of ponds, including those created on nature reserves specifically for wildlife, old field ponds (at least 150 years old) primarily created for watering livestock and subsidence ponds outside protected areas or amongst coastal dunes. No one pond type supported all the species. Larger, deeper ponds on nature reserves had the highest numbers of species within individual ponds but shallow, temporary sites on farm land supported a distinct temporary water fauna. The conservation of pond snails in this region requires a diversity of pond types rather than one idealised type and ponds scattered throughout the area at a variety of sites, not just concentrated on nature reserves