281 research outputs found

    Fall Movements of Belugas (Delphinapterus leucas) with Satellite-linked Transmitters in Lancaster Sound, Jones Sound, and Northern Baffin Bay

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    Six adult belugas, Delphinapterus leucas, (2 males, 4 females) were instrumented with satellite-linked transmitters in Croker Bay, southeastern Devon Island in the Canadian High Arctic in mid-September 1995. Some days, the animals remained close to shore along the southeastern and eastern shoreline of Devon Island, presumably foraging for arctic cod (Boreogadus saida) and other prey. They spent the rest of the time in the deep waters of Lady Ann Strait, eastern Jones Sound, and the waters southeast of Coburg Island, presumably feeding on deepwater prey. Only males went farther north in water off southeastern Ellesmere Island, the belugas' swimming speeds decreased in the later part of the study period. Their last transmissions came from the North Water, an area where belugas are known to winter. Results of this study were not sufficient to determine the extent of movement of belugas between the eastern Canadian Arctic and Greenland.À la mi-septembre 1995, on a installĂ© des Ă©metteurs en liaison avec un satellite sur six bĂ©lugas adultes (Delphinapterus leucas) - 2 mĂąles, 4 femelles - dans la baie Croker, au sud-est de l'Ăźle Devon dans l'ExtrĂȘme-Arctique canadien. Certains jours, les six bĂ©lugas se tenaient prĂšs de la cĂŽte sud-est et est de l'Ăźle Devon, probablement Ă  la recherche de morue arctique (Boreogadus saida) ou d'autres proies. Ils ont passĂ© le reste du temps dans les eaux profondes du dĂ©troit de Lady Ann, de l'est du dĂ©troit de Jones, et dans les eaux du sud-est de l'Ăźle Coburg, se nourrissant probablement de proies habitant les grands fonds. Seuls les mĂąles se sont rendus plus au nord dans les eaux au large du sud-est de l'Ăźle Ellesmere. La vitesse de nage des bĂ©lugas a diminuĂ© durant la derniĂšre portion de l'Ă©tude. Les derniers signaux provenaient de l'Eau du Nord, une rĂ©gion oĂč l'on sait que les bĂ©lugas passent l'hiver. Les rĂ©sultats de cette Ă©tude sont insuffisants pour Ă©valuer l'ampleur des dĂ©placements de bĂ©lugas entre l'est de l'Arctique canadien et le Groenland

    Hematology and Plasma Chemistry as Indicators of Health and Ecological Status In Beluga Whales, Delphinapterus Leucas

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    The capture of beluga whales, Delphinapterus leucas, for instrumentation or tagging afforded the opportunity to collect blood, which was analyzed to evaluate the animals' health and gain information on basic physiological systems. Here, we report on hematological and plasma chemical constituents in samples obtained from 183 belugas, 55 of which were handled during attempts to apply tracking instruments. The other 128 samples were either drawn from live belugas captured for exhibit in zoological parks or research or obtained from the fresh carcasses of whales taken by Inuit hunters. The data span a 15-year period beginning in 1983 and represent various beluga stocks in the Canadian Arctic. The majority of the specimens were collected during the summer or estuarine phase of the belugas' annual cycle. Comparisons by age group, sex, stock, season, and year revealed significant differences in most of the cellular and chemical constituents examined. These results demonstrate some of the variability that might be encountered when examining a "random" selection of belugas at a particular location and time. Immature-sized whales had higher leucocyte counts, electrolyte concentrations, enzyme activity, total protein, albumin, hemoglobin, and some metabolites than older animals. Sex alone was associated with few hematological and plasma chemical differences. Seasonal variation in thyroid hormone activity was linked to marked environmental changes associated with the transition from cold oceanic waters to relatively warm estuaries. Two belugas recaptured 19 and 24 days after instrumentation showed changes in leucocyte counts, hematocrit, and a variety of plasma chemical constituents, some of which indicate inflammation and a likely physiological response to handling and tagging stresses.On a profitĂ© du fait qu'on capturait des bĂ©lougas, Delphinapterus leucas, en vue de les Ă©quiper d'instruments ou de les marquer, pour prĂ©lever des Ă©chantillons de sang qu'on a ensuite analysĂ©s afin d'Ă©valuer l'Ă©tat de santĂ© des individus et de collecter de l'information sur leurs grands systĂšmes physiologiques. Nous prĂ©sentons ici un rapport sur les constituants hĂ©matologiques et chimiques du plasma dans des Ă©chantillons provenant de 183 bĂ©lougas, dont 55 ont Ă©tĂ© manipulĂ©s au cours de tentatives visant Ă  les Ă©quiper d'instruments de poursuite. Les 128 autres Ă©chantillons ont Ă©tĂ© obtenus soit de bĂ©lougas vivants capturĂ©s en vue d'ĂȘtre placĂ©s dans des zoos ou pour la recherche, soit de carcasses fraĂźches de baleines prises par les chasseurs inuits. Les donnĂ©es couvrent une pĂ©riode de 15 ans, commençant en 1983, et reprĂ©sentent divers stocks de bĂ©lougas de l'ocĂ©an Arctique canadien. La plupart des spĂ©cimens ont Ă©tĂ© recueillis durant l'Ă©tĂ© ou durant la phase estuarienne du cycle annuel du bĂ©louga. Des comparaisons par groupe d'Ăąge, sexe, stock, saison et annĂ©e ont rĂ©vĂ©lĂ© des diffĂ©rences marquĂ©es dans la plupart des constituants cellulaires et chimiques examinĂ©s. Ces rĂ©sultats font ressortir une certaine variabilitĂ© Ă  laquelle on peut s'attendre quand on Ă©tudie un Ă©chantillon "alĂ©atoire" de bĂ©lougas pris Ă  un endroit et Ă  un moment donnĂ©s. Par rapport Ă  des individus plus ĂągĂ©s, les baleines qui n'avaient pas atteint leur taille adulte avaient un compte de globules blancs plus Ă©levĂ©, de mĂȘme qu'une plus forte concentration d'Ă©lectrolytes, une plus grande activitĂ© enzymatique, et un taux plus fort d'albumine, d'hĂ©moglobine et de certains mĂ©tabolites. Le sexe seul n'Ă©tait associĂ© qu'Ă  quelques diffĂ©rences hĂ©matologiques et chimiques du plasma. Une variation saisonniĂšre de l'activitĂ© des hormones thyroĂŻdiennes Ă©tait liĂ©e Ă  des changements nets du milieu correspondant Ă  la transition des eaux froides ocĂ©aniques aux estuaires relativement chauds. Deux bĂ©lougas recapturĂ©s 19 et 24 jours aprĂšs avoir Ă©tĂ© Ă©quipĂ©s d'instruments montraient des changements dans le compte de globules blancs, dans l'hĂ©matocrite et dans divers constituants chimiques du plasma, dont certains rĂ©vĂšlent une inflammation et probablement une rĂ©action physiologique au stress dĂ» Ă  la manipulation et au marquage

    Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

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    Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

    Impacts of the Tropical Pacific/Indian Oceans on the Seasonal Cycle of the West African Monsoon

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    The current consensus is that drought has developed in the Sahel during the second half of the twentieth century as a result of remote effects of oceanic anomalies amplified by local land–atmosphere interactions. This paper focuses on the impacts of oceanic anomalies upon West African climate and specifically aims to identify those from SST anomalies in the Pacific/Indian Oceans during spring and summer seasons, when they were significant. Idealized sensitivity experiments are performed with four atmospheric general circulation models (AGCMs). The prescribed SST patterns used in the AGCMs are based on the leading mode of covariability between SST anomalies over the Pacific/Indian Oceans and summer rainfall over West Africa. The results show that such oceanic anomalies in the Pacific/Indian Ocean lead to a northward shift of an anomalous dry belt from the Gulf of Guinea to the Sahel as the season advances. In the Sahel, the magnitude of rainfall anomalies is comparable to that obtained by other authors using SST anomalies confined to the proximity of the Atlantic Ocean. The mechanism connecting the Pacific/Indian SST anomalies with West African rainfall has a strong seasonal cycle. In spring (May and June), anomalous subsidence develops over both the Maritime Continent and the equatorial Atlantic in response to the enhanced equatorial heating. Precipitation increases over continental West Africa in association with stronger zonal convergence of moisture. In addition, precipitation decreases over the Gulf of Guinea. During the monsoon peak (July and August), the SST anomalies move westward over the equatorial Pacific and the two regions where subsidence occurred earlier in the seasons merge over West Africa. The monsoon weakens and rainfall decreases over the Sahel, especially in August.Peer reviewe

    Searches for gravitational waves from known pulsars at two harmonics in 2015-2017 LIGO data

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    International audienceWe present a search for gravitational waves from 222 pulsars with rotation frequencies ≳10 Hz. We use advanced LIGO data from its first and second observing runs spanning 2015–2017, which provides the highest-sensitivity gravitational-wave data so far obtained. In this search we target emission from both the l = m = 2 mass quadrupole mode, with a frequency at twice that of the pulsar’s rotation, and the l = 2, m = 1 mode, with a frequency at the pulsar rotation frequency. The search finds no evidence for gravitational-wave emission from any pulsar at either frequency. For the l = m = 2 mode search, we provide updated upper limits on the gravitational-wave amplitude, mass quadrupole moment, and fiducial ellipticity for 167 pulsars, and the first such limits for a further 55. For 20 young pulsars these results give limits that are below those inferred from the pulsars’ spin-down. For the Crab and Vela pulsars our results constrain gravitational-wave emission to account for less than 0.017% and 0.18% of the spin-down luminosity, respectively. For the recycled millisecond pulsar J0711−6830 our limits are only a factor of 1.3 above the spin-down limit, assuming the canonical value of 1038 kg m2 for the star’s moment of inertia, and imply a gravitational-wave-derived upper limit on the star’s ellipticity of 1.2 × 10−8. We also place new limits on the emission amplitude at the rotation frequency of the pulsars

    Vapor phase preparation and characterization of the carbon micro-coils

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    A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo

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    Abstract: This paper presents the gravitational-wave measurement of the Hubble constant (H 0) using the detections from the first and second observing runs of the Advanced LIGO and Virgo detector network. The presence of the transient electromagnetic counterpart of the binary neutron star GW170817 led to the first standard-siren measurement of H 0. Here we additionally use binary black hole detections in conjunction with galaxy catalogs and report a joint measurement. Our updated measurement is H 0 = 69−8+16 km s−1 Mpc−1 (68.3% of the highest density posterior interval with a flat-in-log prior) which is an improvement by a factor of 1.04 (about 4%) over the GW170817-only value of 69−8+17 km s−1 Mpc−1. A significant additional contribution currently comes from GW170814, a loud and well-localized detection from a part of the sky thoroughly covered by the Dark Energy Survey. With numerous detections anticipated over the upcoming years, an exhaustive understanding of other systematic effects are also going to become increasingly important. These results establish the path to cosmology using gravitational-wave observations with and without transient electromagnetic counterparts

    Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3a

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    We search for gravitational-wave transients associated with gamma-ray bursts detected by the Fermi and Swift satellites during the first part of the third observing run of Advanced LIGO and Advanced Virgo (1 April 2019 15:00 UTC - 1 October 2019 15:00 UTC). 105 gamma-ray bursts were analyzed using a search for generic gravitational-wave transients; 32 gamma-ray bursts were analyzed with a search that specifically targets neutron star binary mergers as short gamma-ray burst progenitors. We describe a method to calculate the probability that triggers from the binary merger targeted search are astrophysical and apply that method to the most significant gamma-ray bursts in that search. We find no significant evidence for gravitational-wave signals associated with the gamma-ray bursts that we followed up, nor for a population of unidentified subthreshold signals. We consider several source types and signal morphologies, and report for these lower bounds on the distance to each gamma-ray burst

    Searches for heavy Higgs bosons in two-Higgs-doublet models and for t → c h decay using multilepton and diphoton final states in p p collisions at 8 TeV

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    Searches are presented for heavy scalar (H) and pseudoscalar (A) Higgs bosons posited in the two doublet model (2HDM) extensions of the standard model (SM). These searches are based on a data sample of pp collisions collected with the CMS experiment at the LHC at a center-of-mass energy of root s = 8 TeV and corresponding to an integrated luminosity of 19.5 fb(-1). The decays H - GT hh and A - GT Zh, where h denotes an SM-like Higgs boson, lead to events with three or more isolated charged leptons or with a photon pair accompanied by one or more isolated leptons. The search results are presented in terms of the H and A production cross sections times branching fractions and are further interpreted in terms of 2HDM parameters. We place 95% C.L. cross section upper limits of approximately 7 pb on sigma B for H - GT hh and 2 pb for A - GT Zh. Also presented are the results of a search for the rare decay of the top quark that results in a charm quark and an SM Higgs boson, t - GT ch, the existence of which would indicate a nonzero flavor-changing Yukawa coupling of the top quark to the Higgs boson. We place a 95% C.L. upper limit of 0.56% on B(t - GT ch)
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