Canadian Beaufort Sea 2000: The Environmental and Social Setting

The Beaufort Sea Conference 2000 brought together a diverse group of scientists and residents of the Canadian Beaufort Sea region to review the current state of the region's renewable resources and to discuss the future management of those resources. In this paper, we briefly describe the physical environment, the social context, and the resource management processes of the Canadian Beaufort Sea region. The Canadian Beaufort Sea land area extends from the Alaska-Canada border east to Amundsen Gulf and includes the northwest of Victoria Island and Banks Island. The area is defined by its geology, landforms, sources of freshwater, ice and snow cover, and climate. The social context of the Canadian Beaufort Sea region has been set by prehistoric Inuit and Gwich'in, European influence, more recent land-claim agreements, and current management regimes for the renewable resources of the Beaufort Sea.La Conférence de l'an 2000 sur la mer de Beaufort a attiré un groupe hétérogène de scientifiques et de résidents de la région de la mer de Beaufort en vue d'examiner le statut actuel des ressources renouvelables de cette zone et de discuter de leur gestion future. Dans cet article, on décrit brièvement l'environnement physique, le contexte social et les processus de gestion des ressources de la zone canadienne de la mer de Beaufort. La superficie terrestre de la mer de Beaufort au Canada s'étend de la frontière entre ce pays et l'Alaska jusqu'au golfe Amundsen à l'est, et elle englobe le nord-ouest de l'île Victoria et de l'île Banks. Cette zone est définie par sa géologie, son relief, ses sources d'eau douce, son couvert glaciel et nival ainsi que son climat. Le contexte social de la région de la mer de Beaufort canadienne a été établi par les Inuits et Gwich'in préhistoriques, l'influence européenne, les récentes ententes territoriales ainsi que les régimes actuels de gestion des ressources renouvelables de la mer de Beaufort

Climate Change and Sea Ice: Local Observations from the Canadian Western Arctic

Can local observations and indigenous knowledge be used to provide information that complements research on climate change? Using participatory research methodology and semi-directed interviews, we explored local and traditional knowledge about changes in sea ice in the area of Sachs Harbour, Northwest Territories. In this small Inuvialuit community, we interviewed all of the 16 community members and elders considered to be local experts on sea ice to ask about their observations. We organized their comments under the headings multiyear ice, first-year ice, fractures and pressure ridges, breakup and freeze-up seasons, and other climate-related variables that influence sea ice (such as changes in winter, spring and summer temperatures, wind, rain, and thunderstorms). Observations were remarkably consistent in providing evidence of local change in such variables as multiyear ice distribution, first-year ice thickness, and ice breakup dates. The changes observed in the 1990s were said to be without precedent and outside the normal range of variation. In assessing the relevance of Inuvialuit knowledge to scientific research on climate change, we note some of the areas in which sharing of information between the two systems of knowledge may be mutually beneficial. These include the analysis of options for adapting to climate change and the generation of research questions and hypotheses for future studies.Est-ce que les observations locales et le savoir des Autochtones peuvent aider à fournir de l'information complétant la recherche sur le changement climatique? En faisant appel à une méthodologie de recherche participative et des entrevues semi-dirigées, on a examiné le savoir local et traditionnel concernant les changements de la banquise dans la région de Sachs Harbour (Territoires du Nord-Ouest). Dans cette petite communauté inuvialuite, on a interviewé les 16 membres et aînés de la communauté considérés comme des experts locaux de la banquise pour les interroger sur leurs observations. On a organisé leurs commentaires sous les rubriques suivantes: glace pluriannuelle, glace de l'année, crêtes de fractures et de pression, saisons de débâcle et d'engel, ainsi que d'autres variables reliées au climat qui influencent la banquise (comme les changements dans les températures hivernale, printanière et estivale, le vent, la pluie et les orages). Il y avait une concordance frappante dans les observations quant aux preuves de changements à l'échelle locale dans des variables comme la distribution de la glace pluriannuelle, l'épaisseur de la glace de l'année et les dates de la débâcle. Les changements observés au cours des années 1990 étaient, selon les Autochtones, sans précédent et ils dépassaient la gamme normale des variations. En évaluant la pertinence du savoir des Inuvialuits pour la recherche scientifique sur le changement climatique, on souligne certains des domaines dans lesquels le partage de l'information entre les deux systèmes de savoir pourrait être mutuellement profitable. Ces domaines comprennent l'analyse des options visant l'adaptation au changement climatique et la formulation de questions et hypothèses de recherche pour des études ultérieures

The Network Architecture of Cortical Processing in Visuo-spatial Reasoning

Reasoning processes have been closely associated with prefrontal cortex (PFC), but specifically emerge from interactions among networks of brain regions. Yet it remains a challenge to integrate these brain-wide interactions in identifying the flow of processing emerging from sensory brain regions to abstract processing regions, particularly within PFC. Functional magnetic resonance imaging data were collected while participants performed a visuo-spatial reasoning task. We found increasing involvement of occipital and parietal regions together with caudal-rostral recruitment of PFC as stimulus dimensions increased. Brain-wide connectivity analysis revealed that interactions between primary visual and parietal regions predominantly influenced activity in frontal lobes. Caudal-to-rostral influences were found within left-PFC. Right-PFC showed evidence of rostral-to-caudal connectivity in addition to relatively independent influences from occipito-parietal cortices. In the context of hierarchical views of PFC organization, our results suggest that a caudal-to-rostral flow of processing may emerge within PFC in reasoning tasks with minimal top-down deductive requirements

The Interstellar Environment of our Galaxy

We review the current knowledge and understanding of the interstellar medium of our galaxy. We first present each of the three basic constituents - ordinary matter, cosmic rays, and magnetic fields - of the interstellar medium, laying emphasis on their physical and chemical properties inferred from a broad range of observations. We then position the different interstellar constituents, both with respect to each other and with respect to stars, within the general galactic ecosystem.Comment: 39 pages, 12 figures (including 3 figures in 2 parts

A measurement of the W boson mass using large rapidity electrons

We present a measurement of the W boson mass using data collected by the D0 experiment at the Fermilab Tevatron during 1994--1995. We identify W bosons by their decays to e-nu final states where the electron is detected in a forward calorimeter. We extract the W boson mass, Mw, by fitting the transverse mass and transverse electron and neutrino momentum spectra from a sample of 11,089 W -> e nu decay candidates. We use a sample of 1,687 dielectron events, mostly due to Z -> ee decays, to constrain our model of the detector response. Using the forward calorimeter data, we measure Mw = 80.691 +- 0.227 GeV. Combining the forward calorimeter measurements with our previously published central calorimeter results, we obtain Mw = 80.482 +- 0.091 GeV

Search for Second Generation Leptoquark Pairs in pbar-p Collisions at sqrt(s) = 1.8 TeV

We have searched for second generation leptoquark (LQ) pairs in the \mu\mu+jets channel using 94+-5 pb^{-1} of pbar-p collider data collected by the D0 experiment at the Fermilab Tevatron during 1993-1996. No evidence for a signal is observed. These results are combined with those from the \mu\nu+jets and \nu\nu+jets channels to obtain 95% confidence level (C.L.) upper limits on the LQ pair production cross section as a function of mass and $beta, the branching fraction of a LQ decay into a charged lepton and a quark. Lower limits of 200(180) GeV/c^2 for \beta=1(1/2) are set at the 95% C.L. on the mass of scalar LQ. Mass limits are also set on vector leptoquarks as a function of \beta.Comment: 6 pages, 4 figures. Submitted to Phys. Rev. Let

Spin Correlation in tt-bar Production from pp-bar Collisions at sqrt(s)=1.8 TeV

The D0 collaboration has performed a study of spin correlation in tt-bar production for the process tt-bar to bb-bar W^+W^-, where the W bosons decay to e-nu or mu-nu. A sample of six events was collected during an exposure of the D0 detector to an integrated luminosity of approximately 125 pb^-1 of sqrt{s}=1.8 TeV pp-bar collisions. The standard model (SM) predicts that the short lifetime of the top quark ensures the transmission of any spin information at production to the tt-bar decay products. The degree of spin correlation is characterized by a correlation coefficient k. We find that k>-0.25 at the 68% confidence level, in agreement with the SM prediction of k=0.88.Comment: Submitted to PRL, Added references, minor changes to tex

Probing BFKL Dynamics in the Dijet Cross Section at Large Rapidity Intervals in ppbar Collisions at sqrt{s}=1800 and 630 GeV

Inclusive dijet production at large pseudorapidity intervals (delta_eta) between the two jets has been suggested as a regime for observing BFKL dynamics. We have measured the dijet cross section for large delta_eta in ppbar collisions at sqrt{s}=1800 and 630 GeV using the DO detector. The partonic cross section increases strongly with the size of delta_eta. The observed growth is even stronger than expected on the basis of BFKL resummation in the leading logarithmic approximation. The growth of the partonic cross section can be accommodated with an effective BFKL intercept of a_{BFKL}(20GeV)=1.65+/-0.07.Comment: Published in Physical Review Letter

Differential Production Cross Section of Z Bosons as a Function of Transverse Momentum at sqrt{s}=1.8 TeV

We present a measurement of the transverse momentum distribution of Z bosons produced in ppbar collisions at sqrt{s}=1.8 TeV using data collected by the D0 experiment at the Fermilab Tevatron Collider during 1994--1996. We find good agreement between our data and a current resummation calculation. We also use our data to extract values of the non-perturbative parameters for a particular version of the resummation formalism, obtaining significantly more precise values than previous determinations.Comment: 10 pages, 2 figures, submitted to Phys. Rev. Letters v2 has margin error correcte

Search for Charged Higgs Bosons in Decays of Top Quark Pairs

We present a search for charged Higgs bosons in decays of pair-produced top quarks using 109.2 +- 5.8 pb^-1 of data recorded from ppbar collisions at sqrt{s} = 1.8 TeV by the D0 detector during 1992-96 at the Fermilab Tevatron. No evidence is found for charged Higgs production, and most parts of the [m(H+),tan(beta)] parameter space where the decay t -> bH+ has a branching fraction close to or larger than that for t -> bW+ are excluded at 95% confidence level. Assuming m(t) = 175 GeV and sigma(ppbar -> ttbar) = 5.5 pb, for m(H+) = 60 GeV, we exclude tan(beta) 40.9.Comment: 11 pages, 3 figures, submitted to PR