The High Subarctic Forest-Tundra of Northwestern Canada: Position, Width, and Vegetation Gradients in Relation to Climate

A phytogeoclimatic study of the high subarctic region of Canada between Hudson Bay and the Cordillera at the northern Yukon-Mackenzie border was undertaken to provide a verifiable and quantitative synthesis of forest-tundra vegetation ecology. Three field seasons of vegetation and terrain studies provided ground truth for a grid of 1314 black-and-white air photos that cover ca. 24% of the forest-tundra and adjacent low Subarctic and low Arctic. Air photos were analyzed for percentage cover of nine vegetation-terrain types, bedrock and parent materials, landforms, and elevations. The forest-tundra, as bounded by the 1000:1 and 1:1000 tree:upland tundra cover isolines, spans an average 145 ± 72 km (median 131 km) and increases in width from northwest to southeast. The transition from 10:1 to 1:10 tree:upland tundra cover occupies one-fourth to one-half the area of the forest-tundra. Regional slope of the land probably accounts for much of the variation in width of the forest-tundra. Southern outliers of forest-tundra in the northwest are found mainly in areas of high elevation. Across much of the northwest, steep vegetation gradients occur near the northern limit of trees. North of Great Slave Lake, steep vegetation gradients shift from the northern to the southern half of the forest-tundra and maintain this position eastward to Hudson Bay. The forest-tundra of the northwest receives roughly three-fourths the mean annual net radiation available to the southeast and central districts.Key words: air photos, boreal, climate, ecology, forest-tundra, high Subarctic, Northwest Territories, plant geography, tree line, vegetationOn a entrepris une étude phytogéoclimatique de la zone de l’Extrême-Subarctique canadien comprise entre la baie d’Hudson et la cordillère, située à la frontière du Yukon-Mackenzie, en vue d’offrir une synthkse vérifiable et quantitative de l’écologie végétale de la forêt-toundra. Trois saisons d’étude de végétation et de terrain ont fourni des données de verification pour une grille de 1314 clichés aériens en noir et blanc, recouvrant environ 24 % de la forêt-toundra et de la zone avoisinante du Bas-Subarctique et du Bas-Arctique. On a analysé les clichés en vue de déterminer le pourcentage de couverture de neuf types de végktation-terrain, de roche de fond et de matériaux mkres, de configurations et de niveaux. La forêt toundra, délimitée par les isarithmes du rapport entre le couvert d’arbres et celui de toundra des hautes terres de IO00 pour 1 et 1 pour 1000, recouvre une bande de largeur moyenne de 145 f 72 km (131 km de mtdiane) et s’klargit en allant du nord-ouest vers le sud-est. La transition du rapport du couvert d’arbres à celui de toundra des hautes terres entre 10 pour 1 et 1 pour 10 occupe de un quart à la moitié de la zone de forêt-toundra. La pente régionale du terrain y est probablement pour beaucoup dans la variation de la largeur de la forêt-toundra. Les îlots méridionaux de forst-toundra dans le Nord-Ouest se trouvent principalement dans les zones de haute altitude. Dans une grande partie du Nord-Ouest, des gradients de végétation brusques se trouvent près de la limite septentrionale des arbres. Au nord du Grand Lac de l’Esclave, des gradients de végétation brusques passent de la moitié septentrionale à la moitié méridionale de la forêt-toundra et conservent cette position vers l’est jusqu’à la baie d’Hudson. La forêt-toundra du Nord-Ouest reçoit environ les trois quarts de la radiation nette annuelle moyenne disponible pour les régions du sud-est et duc entre.Mots clés: clichés aériens, boréal, climat, écologie, forêt-toundra, Extrême-Subarctique. Territoires du Nord-Ouest, géographie de la végktation, ligne des arbres, végétatio

The use of admissions simulation to stabilize ancillary workloads

As part of the planning of a new hospital, an analysis was per formed to determine the number of procedures that would be performed in each of nineteen ancillary departments on a day of the week basis. Because the planned occupancy was not the maximum possible, attempts were made using simulation to smooth the daily ancillary loads by varying the admission day of elective, urgent inpatient and outpatient loads. The methodology, sample outputs, and main conclusions are presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69095/2/10.1177_003754978404300203.pd

Production and processing studies on calpain-system gene markers for tenderness in Brahman cattle: 2. Objective meat quality

Effects and interactions of calpain-system tenderness gene markers on objective meat quality traits of Brahman (Bos indicus) cattle were quantified within 2 concurrent experiments at different locations. Cattle were selected for study from commercial and research herds at weaning based on their genotype for cal-pastatin (CAST) and calpain 3 (GAPN3) gene markers for beef tenderness. Gene marker status for i-calpain (CAPN1-4751 and CAPN1-316) was also determined for inclusion in statistical analyses. Eighty-two heifer and 82 castrated male cattle with 0 or 2 favorable alleles for CAST and CAPN3 were studied in New South Wales (NSW), and 143 castrated male cattle with 0, 1, or 2 favorable alleles for CAST and CAPN3 were studied in Western Australia (WA). The cattle were backgrounded for 6 to 8 mo and grain-fed for 117 d (NSW) or 80 d (WA) before slaughter. One-half the cattle in each experiment were implanted with a hormonal growth promotant during feedlotting. One side of each carcass was suspended from the Achilles tendon (AT) and the other from the pelvis (tenderstretch). The M. longissimus lumborum from both sides and the M. semitendinosus from the AT side were collected; then samples of each were aged at 1°C for 1 or 7 d. Favorable alleles for one or more markers reduced shear force, with little effect on other meat quality traits. The size of effects of individual markers varied with site, muscle, method of carcass suspension, and aging period. Individual marker effects were additive as evident in cattle with 4 favorable alleles for CAST and CAPN3 markers, which had shear force reductions of 12.2 N (P 0.05) of interactions between the gene markers, or between the hormonal growth promotant and gene markers for any meat quality traits. This study provides further evidence that selection based on the CAST or CAPN3 gene markers improves meat tenderness in Brahman cattle, with little if any detrimental effects on other meat quality traits. The CAPN1-4751 gene marker also improved beef tenderness without affecting other objective meat quality traits in heterozygous cattle compared with homozygotes for the unfavorable allele

Speckle variance OCT for depth resolved assessment of the viability of bovine embryos

The morphology of embryos produced by in vitro fertilization (IVF) is commonly used to estimate their viability. However, imaging by standard microscopy is subjective and unable to assess the embryo on a cellular scale after compaction. Optical coherence tomography is an imaging technique that can produce a depth-resolved profile of a sample and can be coupled with speckle variance (SV) to detect motion on a micron scale. In this study, day 7 post-IVF bovine embryos were observed either short-term (10 minutes) or longterm (over 18 hours) and analyzed by swept source OCT and SV to resolve their depth profile and characterize micron-scale movements potentially associated with viability. The percentage of en face images showing movement at any given time was calculated as a method to detect the vital status of the embryo. This method could be used to measure the levels of damage sustained by an embryo, for example after cryopreservation, in a rapid and non-invasive way

New Insights into White-Light Flare Emission from Radiative-Hydrodynamic Modeling of a Chromospheric Condensation

(abridged) The heating mechanism at high densities during M dwarf flares is poorly understood. Spectra of M dwarf flares in the optical and near-ultraviolet wavelength regimes have revealed three continuum components during the impulsive phase: 1) an energetically dominant blackbody component with a color temperature of T $\sim$ 10,000 K in the blue-optical, 2) a smaller amount of Balmer continuum emission in the near-ultraviolet at lambda $<$ 3646 Angstroms and 3) an apparent pseudo-continuum of blended high-order Balmer lines. These properties are not reproduced by models that employ a typical "solar-type" flare heating level in nonthermal electrons, and therefore our understanding of these spectra is limited to a phenomenological interpretation. We present a new 1D radiative-hydrodynamic model of an M dwarf flare from precipitating nonthermal electrons with a large energy flux of $10^{13}$ erg cm$^{-2}$ s$^{-1}$. The simulation produces bright continuum emission from a dense, hot chromospheric condensation. For the first time, the observed color temperature and Balmer jump ratio are produced self-consistently in a radiative-hydrodynamic flare model. We find that a T $\sim$ 10,000 K blackbody-like continuum component and a small Balmer jump ratio result from optically thick Balmer and Paschen recombination radiation, and thus the properties of the flux spectrum are caused by blue light escaping over a larger physical depth range compared to red and near-ultraviolet light. To model the near-ultraviolet pseudo-continuum previously attributed to overlapping Balmer lines, we include the extra Balmer continuum opacity from Landau-Zener transitions that result from merged, high order energy levels of hydrogen in a dense, partially ionized atmosphere. This reveals a new diagnostic of ambient charge density in the densest regions of the atmosphere that are heated during dMe and solar flares.Comment: 50 pages, 2 tables, 13 figures. Accepted for publication in the Solar Physics Topical Issue, "Solar and Stellar Flares". Version 2 (June 22, 2015): updated to include comments by Guest Editor. The final publication is available at Springer via http://dx.doi.org/10.1007/s11207-015-0708-

Complex master-slave enhanced optical coherence microscopy

We present an instrument designed to facilitate localization and high-resolution, optical coherence microscopy (OCM) imaging of small biological samples immersed in a medium several orders of magnitude greater in volume. A modified turret-equipped microscope stand was inserted into the sample arm of a spectral domain optical coherence microscopy (SD-OCM) system. The instrument enabled swift change of imaging objectives through the incorporation of complex master-slave interferometry (CMSI), providing tolerance to dispersion for any objective through the acquisition of a few (≥2) calibration spectra. We demonstrate the instrument’s ability to localize and image samples by providing examples of its application to optical phantoms and to a porcine oocyte immersed in a biological culture medium

Fitting the integrated Spectral Energy Distributions of Galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02