2,529 research outputs found

    Hypoxia In The Lower St. Lawrence Estuary: How Physics Controls Spatial Patterns

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    ISI Document Delivery No.: 980RD Times Cited: 1 Cited Reference Count: 57 Cited References: Anschutz P, 2000, GEOCHIM COSMOCHIM AC, V64, P2751, DOI 10.1016/S0016-7037(00)00400-2 Benoit P, 2006, MAR CHEM, V102, P13, DOI 10.1016/j.marchem.2005.09.015 Bograd SJ, 2008, GEOPHYS RES LETT, V35, DOI 10.1029/2008GL034185 Bugden G.L., 1991, CANADIAN SPECIAL PUB, V113, P139 CHAPMAN DC, 1985, J PHYS OCEANOGR, V15, P1060, DOI 10.1175/1520-0485(1985)0152.0.CO;2 Cloern JE, 2001, MAR ECOL PROG SER, V210, P223, DOI 10.3354/meps210223 Colombo JC, 1996, MAR CHEM, V51, P277, DOI 10.1016/0304-4203(95)00059-3 Colombo JC, 1996, MAR CHEM, V51, P295, DOI 10.1016/0304-4203(95)00060-7 Craig J, 2008, AZMP B PMZA, V7, P37 Czeschel R, 2011, J GEOPHYS RES-OCEANS, V116, DOI 10.1029/2010JC006565 Diaz R. J., 2009, HYPOXIA, P1, DOI 10.1016/S1546-5098(08)00001-0 Diaz RJ, 2001, J ENVIRON QUAL, V30, P275 Dickie L.M., 1983, ESTUARIES ENCLOSED S, P403 Galbraith PS, 2006, J GEOPHYS RES-OCEANS, V111, DOI 10.1029/2005JC003159 Genovesi L, 2011, LIMNOL OCEANOGR, V56, P1319, DOI 10.4319/lo.2011.56.4.1319 Gilbert D, 2005, LIMNOL OCEANOGR, V50, P1654 Gilbert D., 2004, ICES ANN SCI C INT C Gilbert D, 2010, BIOGEOSCIENCES, V7, P2283, DOI 10.5194/bg-7-2283-2010 Gilbert D, 1997, CAN J FISH AQUAT SCI, V54, P57, DOI 10.1139/cjfas-54-S1-57 GLUD RN, 1994, DEEP-SEA RES PT I, V41, P1767 Grasshoff K, 1999, METHODS SEAWATER ANA, DOI DOI 10.1002/9783527613984 GRATTON Y, 1988, J GEOPHYS RES-OCEANS, V93, P6947, DOI 10.1029/JC093iC06p06947 Gutknecht E., 2011, BIOGEOSCI DISCUSS, V8, P3537, DOI DOI 10.5194/BGD-8-3537-2011 Han GQ, 1999, J PHYS OCEANOGR, V29, P1279, DOI 10.1175/1520-0485(1999)0292.0.CO;2 Johnson C., 1987, NUMERICAL SOLUTION P Katsev S, 2007, LIMNOL OCEANOGR, V52, P2555, DOI 10.4319/lo.2007.52.6.2555 Koutitonsky V. G., 1991, CAN SPEC PUBL FISH A, V113, P139 LARGE WG, 1994, REV GEOPHYS, V32, P363, DOI 10.1029/94RG01872 LeBlond P. H., 1978, WAVES OCEAN LEDWELL JR, 1993, NATURE, V364, P701, DOI 10.1038/364701a0 Lehmann MF, 2009, LIMNOL OCEANOGR, V54, P2157, DOI 10.4319/lo.2009.54.6.2157 LUCOTTE M, 1991, ESTUAR COAST SHELF S, V32, P297, DOI 10.1016/0272-7714(91)90022-4 Matear RJ, 2003, GLOBAL BIOGEOCHEM CY, V17, DOI 10.1029/2002GB001997 Mathworks Inc, 2006, PART DIFF EQ TOOLB U Mohrholz V, 2008, CONT SHELF RES, V28, P424, DOI 10.1016/j.csr.2007.10.001 Monteiro PMS, 2011, ENVIRON RES LETT, V6, DOI 10.1088/1748-9326/6/2/025002 Monteiro PMS, 2008, DEEP-SEA RES PT I, V55, P435, DOI 10.1016/j.dsr.2007.12.010 Monteiro PMS, 2006, GEOPHYS RES LETT, V33, DOI 10.1029/2006GL026234, Monteiro PMS, 1999, ESTUAR COAST SHELF S, V49, P877, DOI 10.1006/ecss.1999.0550 Muzuka ANN, 1999, MAR GEOL, V160, P251, DOI 10.1016/S0025-3227(99)00022-5 Ozsoy E, 1997, EARTH-SCI REV, V42, P231, DOI 10.1016/S0012-8252(97)81859-4 Packard T.T., 1985, Advances in Aquatic Microbiology, V3, P207 Pena MA, 2010, BIOGEOSCIENCES, V7, P933 Saucier FJ, 2003, J GEOPHYS RES-OCEANS, V108, DOI 10.1029/2000JC000686 SAVENKOFF C, 1995, CONT SHELF RES, V15, P613, DOI 10.1016/0278-4343(94)00041-K Savenkoff C, 2001, ESTUAR COAST SHELF S, V52, P565, DOI 10.1006/ecss.2001.0774 Savenkoff C, 1996, CAN J FISH AQUAT SCI, V53, P2451, DOI 10.1139/cjfas-53-11-2451 Sherwood OA, 2011, P NATL ACAD SCI USA, V108, P1011, DOI 10.1073/pnas.1004904108 Silverberg N, 2000, DEEP-SEA RES PT II, V47, P699, DOI 10.1016/S0967-0645(99)00123-X Smith GC, 2006, J PHYS OCEANOGR, V36, P1485, DOI 10.1175/JPO2927.1 Smith JN, 1999, LIMNOL OCEANOGR, V44, P207 Taylor KE, 2001, J GEOPHYS RES-ATMOS, V106, P7183, DOI 10.1029/2000JD900719 TEE KT, 1989, J GEOPHYS RES-OCEANS, V94, P8075, DOI 10.1029/JC094iC06p08075 Thibodeau B, 2010, GEOPHYS RES LETT, V37, DOI 10.1029/2010GL044771 Thibodeau B, 2006, MAR GEOL, V231, P37, DOI 10.1016/j.margeo.2006.05.010 VOSJAN JH, 1987, LIMNOL OCEANOGR, V32, P767 VOSJAN JH, 1990, NETH J SEA RES, V25, P89, DOI 10.1016/0077-7579(90)90011-5 Lefort, S. Gratton, Y. Mucci, A. Dadou, I. Gilbert, D. Gilbert, Denis/A-3067-2010 Gilbert, Denis/0000-0002-9554-9594 NSERC Strategic grant; DFO CCSI (Climate Change Science Initiative) grant; Department of Earth and Planetary Sciences/McGill; GEOTOP-UQAM-McGill research center; LEGOS laboratory; University of Toulouse III (Paul Sabatier, France) This research was funded by a NSERC Strategic grant to A.M., D.G. and Y.G, and a DFO CCSI (Climate Change Science Initiative) grant to D.G. Additional financial support to S.L. was provided by the Department of Earth and Planetary Sciences/McGill, the GEOTOP-UQAM-McGill research center, the LEGOS laboratory and the University of Toulouse III (Paul Sabatier, France). We thank the captains and crew of R/V Alcide C. Horth and R/V Coriolis II for their help during the numerous cruises between 2002 and 2011. We acknowledge the two anonymous reviewers for their insightful comments. 1 AMER GEOPHYSICAL UNION WASHINGTON J GEOPHYS RES-OCEANSA laterally integrated advection-diffusion two-dimensional model was implemented to simulate the spatial distribution of dissolved oxygen and the development of hypoxic conditions in the deep waters of the Laurentian Channel (Estuary and Gulf of St. Lawrence, Eastern Canada). Our simulations reveal that the horizontal distribution of dissolved oxygen in the bottom waters of the Laurentian Channel is determined by a combination of physical and biogeochemical processes, whereas its vertical distribution is governed by the deep water circulation. This result strongly suggests that the physics of the system and the source water properties are mostly responsible for the generation of a mid-water column oxygen minimum and the oxygen distribution pattern in the deep water column

    Tracking the phase-transition energy in disassembly of hot nuclei

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    In efforts to determine phase transitions in the disintegration of highly excited heavy nuclei, a popular practice is to parametrise the yields of isotopes as a function of temperature in the form Y(z)=zτf(zσ(TT0))Y(z)=z^{-\tau}f(z^{\sigma}(T-T_0)), where Y(z)Y(z)'s are the measured yields and τ,σ\tau, \sigma and T0T_0 are fitted to the yields. Here T0T_0 would be interpreted as the phase transition temperature. For finite systems such as those obtained in nuclear collisions, this parametrisation is only approximate and hence allows for extraction of T0T_0 in more than one way. In this work we look in detail at how values of T0T_0 differ, depending on methods of extraction. It should be mentioned that for finite systems, this approximate parametrisation works not only at the critical point, but also for first order phase transitions (at least in some models). Thus the approximate fit is no guarantee that one is seeing a critical phenomenon. A different but more conventional search for the nuclear phase transition would look for a maximum in the specific heat as a function of temperature T2T_2. In this case T2T_2 is interpreted as the phase transition temperature. Ideally T0T_0 and T2T_2 would coincide. We invesigate this possibility, both in theory and from the ISiS data, performing both canonical (TT) and microcanonical (e=E/Ae=E^*/A) calculations. Although more than one value of T0T_0 can be extracted from the approximate parmetrisation, the work here points to the best value from among the choices. Several interesting results, seen in theoretical calculations, are borne out in experiment.Comment: Revtex, 10 pages including 8 figures and 2 table

    Projectile fragmentation reactions and production of nuclei near the neutron drip-line

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    The reaction mechanism of projectile fragmentation at intermediate energies has been investigated observing the target dependence of the production cross sections of very neutron-rich nuclei. Measurement of longitudinal momentum distributions of projectile-like fragments within a wide range of fragment mass and its charge was performed using a hundred-MeV/n 40^{40}Ar beam incident on Be and Ta targets. By measurement of fragment momentum distribution, a parabolic mass dependence of momentum peak shift was observed in the results of both targets, and a phenomenon of light-fragment acceleration was found only in the Be-target data. The analysis of production cross sections revealed an obvious enhancement of the target dependence except target size effect when the neutron excess is increased. This result implies the breakdown of factorization (BOF) of production cross sections for very neutron-rich nuclei near the drip line.Comment: 16 pages, 18 figures, submitted to Phys. Rev.

    Phytophthora polonica, a new species isolated from declining Alnus glutinosa stands in Poland

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    In a survey of Phytophthora associated with alder decline in Poland, several isolates of a homothallic Phytophthora spet al, which could not be assigned to other taxa including Phytophthora alni subspecies, were consistently recovered from rhizosphere soil samples. Their morphology and pathogenicity, as well as sequence data for three nuclear regions (internal transcribed spacer rDNA, elongation factor-1α and β-tubulin) and a coding mitochondrial DNA region (nadh1), were examined. The new Phytophthora species is characterized by the moderate to slow growth rate of its colony in carrot agar at 20°C, high optimal (c. 30°C) and maximum (c. 38°C) growth temperatures, formation of catenulate, often lateral, hyphal swellings, large chlamydospores in agar media and in soil extract, persistent, ovoid to ellipsoid nonpapillate sporangia and large oogonia with paragynous and sometimes amphigynous antheridia. Phytophthora polonica was slightly pathogenic to alder twigs and not pathogenic to trunks of several tree species. In a phylogenetic analysis using either Bayesian inference or maximum likelihood methods, P. polonica falls in clade 8 ‘sensu Kroon (2004)' of Phytophthor

    Prospects for the discovery of the next new element: Influence of projectiles with Z > 20

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    The possibility of forming new superheavy elements with projectiles having Z > 20 is discussed. Current research has focused on the fusion of 48Ca with actinides targets, but these reactions cannot be used for new element discoveries in the future due to a lack of available target material. The influence on reaction cross sections of projectiles with Z > 20 have been studied in so-called analog reactions, which utilize lanthanide targets carefully chosen to create compound nuclei with energetics similar to those found in superheavy element production. The reactions 48Ca, 45Sc, 50Ti, 54Cr + 159Tb, 162Dy have been studied at the Cyclotron Institute at Texas A&M University using the Momentum Achromat Recoil Spectrometer. The results of these experimental studies are discussed in terms of the influence of collective enhancements to level density for compound nuclei near closed shells, and the implications for the production of superheavy elements. We have observed no evidence to contradict theoretical predictions that the maximum cross section for the 249Cf(50Ti, 4n)295120 and 248Cm(54Cr, 4n)298120 reactions should be in the range of 10-100 fb.Comment: An invited talk given by Charles M. Folden III at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. Also contains information presented by Dmitriy A. Mayorov and Tyler A. Werke in separate contributions to the conference. This contribution will appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

    A detailed study of the diastereoselective catalytic hydrogenation of 6-hydroxytetrahydroisoquinoline-(3R)-carboxylic ester intermediates

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    A key step towards a highly-selective antagonist of ionotropic glutamate receptors entails the diastereoselective arene hydrogenation of an enantiopure tetrahydroisoquinoline. An extensive screen using parallel reactors was conducted and led to the discovery of several Pd/C catalysts giving high yield and improved diastereoselectivity from 75 : 25 to 95 : 5. A detailed kinetic study of the best system was performed and supports the reduction occuring in two-steps.

    Rich polymorphism of a rod-like liquid crystal (8CB) confined in two types of unidirectional nanopores

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    We present a neutron and X-rays scattering study of the phase transitions of 4-n-octyl-4'-cyanobiphenyl (8CB) confined in unidirectional nanopores of porous alumina and porous silicon (PSi) membranes with an average diameter of 30 nm. Spatial confinement reveals a rich polymorphism, with at least four different low temperature phases in addition to the smectic A phase. The structural study as a function of thermal treatments and conditions of spatial confinement allows us to get insights into the formation of these phases and their relative stability. It gives the first description of the complete phase behavior of 8CB confined in PSi and provides a direct comparison with results obtained in bulk conditions and in similar geometric conditions of confinement but with reduced quenched disorder effects using alumina anopore membranesComment: Accepted in EPJ E - Soft Matte

    Dual tumor suppressing and promoting function of Notch1 signaling in human prostate cancer.

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    Adenocarcinomas of the prostate arise as multifocal heterogeneous lesions as the likely result of genetic and epigenetic alterations and deranged cell-cell communication. Notch signaling is an important form of intercellular communication with a role in growth/differentiation control and tumorigenesis. Contrasting reports exist in the literature on the role of this pathway in prostate cancer (PCa) development. We show here that i) compared to normal prostate tissue, Notch1 expression is significantly reduced in a substantial fraction of human PCas while it is unaffected or even increased in others; ii) acute Notch activation both inhibits and induces process networks associated with prostatic neoplasms; iii) down-modulation of Notch1 expression and activity in immortalized normal prostate epithelial cells increases their proliferation potential, while increased Notch1 activity in PCa cells suppresses growth and tumorigenicity through a Smad3-dependent mechanism involving p21WAF1/CIP1; iv) prostate cancer cells resistant to Notch growth inhibitory effects retain Notch1-induced upregulation of pro-oncogenic genes, like EPAS1 and CXCL6, also overexpressed in human PCas with high Notch1 levels. Taken together, these results reconcile conflicting data on the role of Notch1 in prostate cancer

    Limitation of energy deposition in classical N body dynamics

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    Energy transfers in collisions between classical clusters are studied with Classical N Body Dynamics calculations for different entrance channels. It is shown that the energy per particle transferred to thermalised classical clusters does not exceed the energy of the least bound particle in the cluster in its ``ground state''. This limitation is observed during the whole time of the collision, except for the heaviest system.Comment: 13 pages, 15 figures, 1 tabl
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