510 research outputs found
Measurements in Turbulent Water and Two-Phase Flows by Laser Anemometry
Measurements of the mean and rms values of the longitudinal velocity in a rectangular duct are reported. These results were obtained in a water flow using a laser anemometer. The important design criteria which facilitated the measurements are described and gradient, transit-time, noise and refractive-index corrections are specifically discussed. The results demonstrate the development of a rectangular duct flow and, in particular, reveal that a small lack of symmetry at the duct entrance can readily be identified in the normal- stress results, 37 hydraulic diameters downstream.
The possibility of utilizing water droplets in steam and gas bubbles in water to scatter light and thereby to assist laser-anemometer studies of turbulence is discussed. Experimental evidence obtained by the authors and their colleagues is used to support the conclusions
Variation in Reproduction and Body Condition of the Ringed Seal (Phoca hispida) in Western Prince Albert Sound, NT, Canada, as Assessed Through a Harvest-based Sampling Program
Between 1992 and 1998, 869 ringed seals taken in the subsistence harvest in western Prince Albert Sound were sampled by two Inuvialuit seal monitors from Holman, Northwest Territories. Considering the 1992-98 data along with data from 1971-78, we found that the mean body-mass index (BMI) values for females (>= 7 yr) were significantly lower in 1974 than in all other years examined. At the same time, ovulation rates fell from 100% in 1971 and 1972 to lows of 42.9% (1974) and 64.3% (1975), with a return to 93.8% in 1976. Mature females that had ovulated had significantly higher BMI values than those that had not ovulated. In eastern Amundsen Gulf, 1974 was the most severe ice year on recent record, with the latest date of clearing of the landfast ice (6 September), the earliest date of new ice formation (4 October), and the fewest number of open water days (28 days). There were no years between 1992 and 1998 that compared to 1974 in reduced ovulation rates, reduced body condition, or severity of ice conditions. Between 1992 and 1998, mean BMI values for adult females and males were lowest in 1994 and highest in 1998, and all annual mean BMI values were between the extremes of the 1970s. This variation in condition in the 1990s did not coincide with a reduction in ovulation rates of mature females, which remained high (93.5-100%) from 1992 to 1998. In 1998, the landfast ice cleared 43 days earlier than the average clearing date for the 1990-98 period, apparently interrupting the lactation period for seal pups located at the periphery of the core breeding habitat. The apparent effects on growth and condition of unweaned pups came at a time when marine food appeared to be abundant and available to all age classes of ringed seals. Entre 1992 et 1998, 869 phoques annelĂ©s pris dans le cadre de la rĂ©colte de subsistance de l'ouest de la baie Prince-Albert ont fait l'objet d'Ă©chantillonnages par deux moniteurs inuvialuits de Holman (T. N.-O.), chargĂ©s de la surveillance des phoques. En tenant compte des donnĂ©es de 1992 Ă 1998 jointes Ă celles de 1971 Ă 1978, on a trouvĂ© que la valeur moyenne de l'index de masse corporelle (IMC) pour les femelles (>= 7 ans) Ă©tait sensiblement infĂ©rieure en 1974 par rapport Ă toutes les autres annĂ©es de l'Ă©tude. En mĂȘme temps, les taux d'ovulation ont chutĂ©, de 100 p. cent qu'ils Ă©taient en 1971 et 1972 Ă 42,9 p. cent en 1974 et Ă 64,3 p. cent en 1975, opĂ©rant une remontĂ©e Ă 93,8 p. cent en 1976. L'IMC des femelles adultes qui avaient ovulĂ© Ă©tait sensiblement plus Ă©levĂ© que celui des femelles adultes qui n'avaient pas ovulĂ©. Dans l'est du golfe Amundsen, l'annĂ©e 1974 fut celle qui connut la plus intense formation de glace enregistrĂ©e rĂ©cemment, avec la date la plus tardive pour la disparition de la glace de rive (6 septembre), la date la plus prĂ©coce pour la formation de la nouvelle glace (4 octobre) et le plus petit nombre de jours de mer libre (28 jours). Entre 1992 et 1998, aucune annĂ©e n'Ă©tait comparable Ă 1974 en ce qui a trait Ă la rĂ©duction des taux d'ovulation, la rĂ©duction de l'Ă©tat corporel ou l'intensitĂ© de la glace. Entre 1992 et 1998, les moyennes de l'IMC pour les femelles et pour les mĂąles adultes Ă©taient les plus basses en 1994 et les plus Ă©levĂ©es en 1998, et toutes les moyennes annuelles de l'IMC se situaient entre les extrĂȘmes des annĂ©es 1970. Cette variation dans l'Ă©tat corporel durant les annĂ©es 1990 n'a pas coĂŻncidĂ© avec une rĂ©duction du taux d'ovulation des femelles adultes, qui est restĂ© Ă©levĂ© (de 93,5 Ă 100 p. cent) de 1992 Ă 1998. En 1998, la glace de rive a disparu 43 jours plus tĂŽt que la date de dĂ©gagement moyenne pour la pĂ©riode se situant entre 1990 et 1998, ce qui semble avoir interrompu la pĂ©riode de lactation pour les bĂ©bĂ©s phoques qui se trouvaient Ă la pĂ©riphĂ©rie de l'habitat de reproduction principal. Les effets apparents sur la croissance et l'Ă©tat des bĂ©bĂ©s phoques se sont produits Ă un moment oĂč le rĂ©seau trophique marin Ă©tait abondant et Ă la portĂ©e de toutes les classes d'Ăąge des phoques annelĂ©s.
Expression of ski can act as a negative feedback mechanism on retinoic acid signaling
Background: Retinoic acid signaling is essential for many aspects of early development in vertebrates. To control the levels of signaling, several retinoic acid target genes have been identified that act to suppress retinoic acid signaling in a negative feedback loop. The nuclear protein Ski has been extensively studied for its ability to suppress transforming growth factor-beta (TGF-ÎČ) signaling but has also been implicated in the repression of retinoic acid signaling. Results: We demonstrate that ski expression is up-regulated in response to retinoic acid in both early Xenopus embryos and in human cell lines. Blocking retinoic acid signaling using a retinoic acid antagonist results in a corresponding decrease in the levels of ski mRNA. Finally, overexpression of SKI in human cells results in reduced levels of CYP26A1 mRNA, a known target of retinoic acid signaling. Conclusions: Our results, coupled with the known ability of Ski to repress retinoic acid signaling, demonstrate that Ski expression is a novel negative feedback mechanism acting on retinoic acid signaling. Developmental Dynamics 242:604-613, 2013. © 2013 Wiley Periodicals, Inc
Kuujjua River Arctic Char: Monitoring Stock Trends Using Catches from an Under-Ice Subsistence Fishery, Victoria Island, Northwest Territories, Canada, 1991 â 2009
A standardized, harvest-based monitoring program was conducted during the main under-ice subsistence fishery for Arctic char (Salvelinus alpinus) of the Kuujjua River for 18 winter fishing seasons between 1991 and 2009. The program was a response to the concern of Ulukhaktok residents that Arctic char were becoming fewer in number and smaller in size. Mean harvests averaged 1225 (SD 262) Arctic char annually for 1996â2002 and 568 (SD 274) in 2003â09, or roughly 40% and 20% of the harvest levels estimated for 1971â78 (2900, SD 842) and 1988â92 (2943, SD 1072). There was no statistical relationship between the size of the annual harvest (number of fish), and the corresponding mean annual catch per unit effort (CPUE) value (R2 = 0.0141, p = 0.761). Arctic char were fully recruited to the fishery at age nine, with 82.4% of the sampled catch (n = 3288) ranging between 8 and 12 years and composed almost exclusively (99%) of non-spawning adults. Over the time series, temporal trends were not detected (p > 0.05) in mean annual CPUE (27.3 Arctic char/100 m/24 h, SD 14.15), mean fork length (593 mm, SD 78.1), or mean age (9.9 years, SD 2.0). Annual mortality rate showed a weak, but significant, decreasing trend over the series (R2 = 0.354), and there were no statistical trends in annual values of the Brody growth coefficient (R2 = 0.1337, p = 0.164). Variation in mean annual somatic condition indices was correlated with timing of sea ice clearance in spring (R2 = 0.474, p = 0.002), probably because prey quality, quantity, or both are higher in summers following earlier spring blooms in the marine environment. Together, the absence of temporal trends in CPUE, fork length, and age of the harvested fish and the apparent improvement in survival (lower mortality), suggest that the stock has been stable at the harvest levels observed during the monitoring period. The stock may also be realizing some improved fitness, which is due to changes in environmental productivity and appears to be linked, at least in part, to the timing of spring breakup in eastern Amundsen Gulf.Entre 1991 et 2009, pendant 18 saisons de pĂȘche hivernale, un programme de surveillance standardisĂ© axĂ© sur les rĂ©coltes a Ă©tĂ© rĂ©alisĂ© quant Ă la pĂȘche de subsistance principale dâomble chevalier (Salvelinus alpinus) sur la riviĂšre Kuujjua. Ce programme a Ă©tĂ© mis en oeuvre Ă la lumiĂšre des inquiĂ©tudes exprimĂ©es par les rĂ©sidents dâUlukhaktok qui affirmaient que le nombre dâombles chevaliers diminuait, tout comme leur taille. De 1996 Ă 2002, la rĂ©colte moyenne dâombles chevaliers atteignait 1 225 (SD 262) annuellement, tandis que de 2003 Ă 2009, la rĂ©colte moyenne annuelle sâĂ©levait Ă 568 (SD de 274), soit environ 40 % et 20 % des rĂ©coltes Ă©valuĂ©es pour les annĂ©es 1971 Ă 1978 (2 900, SD de 842) et les annĂ©es 1988 Ă 1992(2 943, SD de 1 072). Il nâexistait pas de lien statistique entre la taille de la rĂ©colte annuelle (le nombre de poissons) et la valeur de la capture par unitĂ© dâeffort (CPUE) moyenne annuelle correspondante (R2 = 0,0141, p = 0,761). Lâomble chevalier Ă©tait pleinement recrutĂ© Ă la pĂȘche Ă lâĂąge de neuf ans, avec 82,4 % de la capture Ă©chantillonnĂ©e (n = 3288) variant entre huit et 12 ans, et composĂ©e presque exclusivement (99 %) dâadultes non encore reproducteurs. Au fil des sĂ©ries, aucune tendance temporelle nâa Ă©tĂ© dĂ©celĂ©e (p > 0,05) sur le plan de la CPUE moyenne annuelle (27,3 ombles chevaliers/100 m/24 h, SD 14,15), de la longueur moyenne Ă la fourche (593 mm, SD 78,1) ou de lâĂąge moyen (9,9 ans, SD 2,0). Le taux de mortalitĂ© annuel indiquait une tendance Ă la baisse Ă la fois faible mais importante au cours des sĂ©ries (R2 = 0,354), et il nây avait pas de tendances statistiques du point de vue des valeurs annuelles du coefficient de croissance de Brody (R2 = 0,1337, p = 0,164). Une corrĂ©lation a Ă©tĂ© Ă©tablie entre lâĂ©cart des indices somatiques annuels moyens et le moment du dĂ©gagement de la glace de mer au printemps (R2 = 0,474, p = 0,002), probablement parce que la qualitĂ© ou la quantitĂ© de proies, ou les deux, est plus Ă©levĂ©e au cours des Ă©tĂ©s qui suivent une prolifĂ©ration printaniĂšre hĂątive dans lâenvironnement marin. Ensemble, lâabsence de tendances temporelles relatives Ă la CPUE, Ă la longueur Ă la fourche et Ă lâĂąge du poisson rĂ©coltĂ© et lâamĂ©lioration apparente de la survie (mortalitĂ© plus faible) suggĂšrent que le stock Ă©tait stable aux niveaux de rĂ©colte observĂ©s pendant la pĂ©riode de surveillance. Par ailleurs, il se pourrait que le stock connaisse une valeur dâadaptation quelque peu amĂ©liorĂ©e, ce qui est attribuable aux changements caractĂ©risant la productivitĂ© environnementale et semble liĂ©, tout au moins en partie, au moment de la dĂ©bĂącle du printemps dans lâest du golfe Amundsen
Ringed Seals and Sea Ice in Canadaâs Western Arctic: Harvest-Based Monitoring 1992â2011
We examined the relationship between ringed seal body condition and reproduction and spring sea ice conditions in prime ringed seal habitat in Canadaâs western Arctic during 1992 â 2011. Since 1970, ice conditions in east Amundsen Gulf and west Prince Albert Sound have shown only a slight trend toward earlier ice clearance (breakup) in spring (3 â 7 days per decade) (p < 0.10) and no trend toward later freeze-up or increased variability in timing of spring ice clearance. A subsistence harvest â based sample of 2281 ringed seals was obtained during 1992 â 2011 from Masoyak, a traditional hunting camp located on the northwest shore of west Prince Albert Sound and less than 5 km from east Amundsen Gulf. The results revealed a statistically significant trend of decreasing mean annual body condition of ringed seals (using an index of length-mass-blubber depth [LMD]: adults, 0.14 m1.5/kg0.5/y; subadults, 0.24 m1.5/kg0.5/y) over the past two decades. A parallel result was that mean annual body condition of adults and subadults was correlated with the timing of fast ice clearance in spring (later ice clearance = worse condition). This correlation was most obvious in the extreme ice years in all sex/age groupings and was statistically significant for subadults. In mature females sampled since 1992, annual ovulation rates averaged 92.4 ± 16.3% (SD) and were greater than 80%, and mostly at 100%, in all years but two. Failure to ovulate was obvious in 2005, the most extreme late ice clearance year in our series, when only 30.0% of the mature adult females sampled ovulated. At the same time, values for seal body condition indices (adult females, LMD = 11.3; adult males, LMD = 12.4) and percent pups in the harvest (3.3%) were among the lowest recorded, and spring ice clearance was 38 d later than the 1992 â 2011 average. While this and previous studies indicate that the seal population in this core habitat has recovered from natural and extreme-year sea ice fluctuations over the past four decades, the potentially magnified effect of several consecutive extreme ice years, compounded by the concurrent decline in seal body condition that we have now detected over the past 20 years, is of particular concern.Nous avons examinĂ© le lien qui existe entre lâĂ©tat corporel du phoque annelĂ©, lâĂ©tat de reproduction de ce phoque et lâĂ©tat de la glace de mer printaniĂšre dans son habitat dâĂ©lection de lâouest de lâArctique canadien et ce, entre 1992 et 2011. Depuis 1970, lâĂ©tat de la glace dans lâest du golfe Amundsen et dans lâouest du dĂ©troit de Prince-Albert nâa affichĂ© quâune petite tendance vers une dĂ©bĂącle printaniĂšre plus hĂątive (de 3 Ă 7 jours par dĂ©cennie) (p < 0,10) et aucune tendance vers un englacement plus tardif ou une variabilitĂ© accrue caractĂ©risant la pĂ©riode de la dĂ©bĂącle du printemps. Un Ă©chantillon recueilli Ă partir de 2 281 phoques annelĂ©s ayant fait lâobjet dâune rĂ©colte de subsistance a Ă©tĂ© obtenu entre 1992 et 2011 Ă Masoyak, un camp de chasse traditionnel situĂ© sur la cĂŽte nord-ouest de lâouest du dĂ©troit de Prince-Albert et Ă moins de cinq kilomĂštres de lâest du golfe Amundsen. Les rĂ©sultats ont permis de constater une tendance statistiquement significative sur le plan de la dĂ©croissance de lâĂ©tat corporel annuel moyen des phoques annelĂ©s (en fonction dâun indice de la profondeur et de la longueur de la masse du petit lard [LMD] : reproducteurs, 0,14 m1,5/kg0,5/a; prĂ©reproducteurs, 0,24 m1,5/kg0,5/a) au cours des deux derniĂšres dĂ©cennies. Un rĂ©sultat parallĂšle a permis de corrĂ©ler lâĂ©tat corporel annuel moyen des reproducteurs et des prĂ©reproducteurs Ă la pĂ©riode dâune dĂ©bĂącle printaniĂšre rapide (dĂ©bĂącle tardive = pire Ă©tat). Cette corrĂ©lation Ă©tait plus Ă©vidente au cours des annĂ©es oĂč la glace Ă©tait extrĂȘme chez tous les groupements en fonction du sexe ou de lâĂąge, et elle Ă©tait statistiquement significative chez les prĂ©reproducteurs. Parmi les femelles matures Ă©chantillonnĂ©es depuis 1992, les taux dâovulation annuels atteignaient 92,4 ± 16,3 % (DS) en moyenne, et Ă©taient plus grands que 80 %, et Ă prĂšs de 100 % au cours de toutes les annĂ©es, sauf deux. Lâanovulation Ă©tait Ă©vidente en 2005, ce qui correspondait Ă lâannĂ©e de notre sĂ©rie oĂč la dĂ©bĂącle a Ă©tĂ© la plus tardive, lorsque seulement 30,0 % des femelles adultes et matures qui avaient Ă©tĂ© Ă©chantillonnĂ©es ont ovulĂ©. En mĂȘme temps, les valeurs relatives aux indices de lâĂ©tat corporel des phoques (femelles adultes, LMD = 11,3; mĂąles adultes, LMD = 12,4) et au pourcentage de petits faisant partie de la rĂ©colte (3,3 %) figuraient parmi les valeurs les plus basses Ă nâavoir jamais Ă©tĂ© enregistrĂ©es, et la dĂ©bĂącle printaniĂšre Ă©tait plus tardive de 38 jours par rapport Ă la moyenne de 1992-2011. Bien que cette Ă©tude et des Ă©tudes antĂ©rieures laissent croire que la population de phoques de cet habitat important a rĂ©ussi Ă se remettre des fluctuations naturelles et extrĂȘmes des conditions de glace des quatre derniĂšres dĂ©cennies, lâeffet potentiellement grossissant de plusieurs annĂ©es consĂ©cutives de glace extrĂȘme, alliĂ© au dĂ©clin concurrent de lâĂ©tat corporel des phoques que nous avons dĂ©celĂ© au cours des 20 derniĂšres annĂ©es, prĂ©sente une source dâinquiĂ©tude particuliĂšre
Seasonal Movements and Diving of Ringed Seals, Pusa hispida, in the Western Canadian Arctic, 1999â2001 and 2010â11
Satellite-linked time-depth recorders were deployed on 17 ringed seals in early summer in 1999, 2000, and 2010, near the Inuvialuit community of Ulukhaktok, Northwest Territories, Canada. The main objective was to investigate movements and diving behaviour of ringed seals in the Prince Albert Sound (PAS) and eastern Amundsen Gulf (EAG) regions in relation to season, sex, and age-class. Tags performed well on 16 of 17 tagged seals, with average tracking periods of 256 d (SD 69, range: 134 â 352). Adult and subadult ringed seals traveled considerable distances throughout the open water period (mean = 5844 km, range = 1232 â 9473 km), using vast home ranges during this season, shown with 90 Percent Volume Contours (90 PVC) averaging 122 854 km2 for subadults, 76 658 km2 for adult females, and 21 649 km2 for adult males. Overall, adults spent 69.5% of the observed open water days in foraging/resident mode and 22.8% in traveling mode. The majority (75%) of total observed foraging/resident time was spent in PAS and EAG. Eleven of 12 adults made forays outside EAG and PAS to distant areas, including Prince of Wales Strait (7 seals), Viscount Melville Sound (6), Minto Inlet (4), western Amundsen Gulf (4), and six other zones. During open water season, subadults spent 36.8% traveling and 51.4% foraging/ resident, also mainly in EAG and PAS (61%), but they all traveled to distant zones, eight in total. During winter, all tagged adult females, five of seven adult males, and three of four subadults returned to PAS and EAG to occupy winter home ranges that were on average 15% of the size of the open water home range (mean winter ranges = 1299 km2 for adult males, 3599 km2 for adult females, and 30 499 km2 for subadults). The mean size of the winter home ranges varied by as much as a factor of 10 among the three winters examined. Seal movements were most restricted during the winters with extensive fast ice (1999 â 2000 and 2010 â 11) and least restricted during the winter (2000 â 01) when fast ice did not form in EAG. In winter, adult females made more long, deep dives than either adult males or subadults.Des enregistreurs de profondeur temporelle en liaison avec un satellite ont Ă©tĂ© dĂ©ployĂ©s sur 17 phoques annelĂ©s au dĂ©but des Ă©tĂ©s 1999, 2000 et 2010 prĂšs de la collectivitĂ© inuvialuite dâUlukhaktok, dans les Territoires du Nord-Ouest, au Canada. Lâobjectif principal consistait Ă Ă©tudier les dĂ©placements et les comportements de plongĂ©e des phoques annelĂ©s des rĂ©gions du dĂ©troit de Prince-Albert (DPA) et de la partie est du golfe Amundsen (EGA) en fonction de la saison, du sexe et de la classe dâĂąge. Les Ă©tiquettes ont donnĂ© des rĂ©sultats valables dans le cas de 16 des 17 phoques Ă©tiquetĂ©s, les pĂ©riodes moyennes de pistage ayant atteint 256 jours (SD 69, Ă©tendue : 134 â 352). Les phoques annelĂ©s adultes et jeunes adultes parcouraient des distances considĂ©rables pendant la pĂ©riode des eaux libres (moyenne = 5 844 km, Ă©tendue = 1 232 â 9 473 km), dans de vastes domaines vitaux au cours de la saison. Les pourcentages du volume des contours de 90 (90 PVC) sâĂ©tablissaient en moyenne Ă 122 854 km2 pour les jeunes adultes, Ă 76 658 km2 pour les femelles adultes et Ă 21 649 km2 pour les mĂąles adultes. Dans lâensemble, les adultes ont passĂ© 69,5 % des journĂ©es observĂ©es en eaux libres en mode dâalimentation et de rĂ©sidence, et 22,8 % en mode de dĂ©placement. La majoritĂ© (75 %) du temps total observĂ© en mode dâalimentation et de rĂ©sidence Ă©tait dans le DPA et lâEGA. Onze adultes sur 12 se sont aventurĂ©s en dehors du DPA et de lâEGA pour atteindre des endroits Ă©loignĂ©s, dont le dĂ©troit du Prince-de-Galles (7 phoques), le dĂ©troit du Vicomte de Melville (6), lâanse Mintot (4), lâouest du golfe Amundsen (4) et six autres zones. Pendant la saison des eaux libres, les jeunes adultes ont passĂ© 36,8 % du temps en mode de dĂ©placement et 51,4 % du temps en mode dâalimentation ou de rĂ©sidence, Ă©galement principalement dans le DPG et lâEGA (61 %), mais ils se sont tous rendus dans des zones Ă©loignĂ©es, huit en tout. Durant lâhiver, toutes les femelles adultes Ă©tiquetĂ©es, cinq mĂąles adultes sur sept et trois jeunes adultes sur quatre sont revenus dans le DPA et lâEGA pour occuper des domaines vitaux hivernaux qui correspondaient, en moyenne, Ă 15 % de la taille du domaine vital en eaux libres (Ă©tendues moyennes des domaines hivernaux = 1 299 km2 pour les mĂąles adultes, 3 599 km2 pour les femelles adultes et 30 499 km2 pour les jeunes adultes). La taille moyenne des domaines vitaux hivernaux a variĂ© en fonction dâun facteur de 10 au cours des trois hivers Ă lâĂ©tude. Le dĂ©placement des phoques Ă©tait plus restreint pendant les hivers oĂč la glace Ă©tait rapide (1999-2000 et 2010-2011) et moins restreint pendant lâhiver (2000-2001) oĂč la glace rapide ne sâest pas formĂ©e dans lâEGA. Lâhiver, les femelles adultes faisaient plus de plongĂ©es longues et profondes que les mĂąles adultes ou les jeunes adultes
Greenhouse gas emissions resulting from conversion of peat swamp forest to oil palm plantation.
Conversion of tropical peat swamp forest to drainage-based agriculture alters greenhouse gas (GHG) production, but the magnitude of these changes remains highly uncertain. Current emissions factors for oil palm grown on drained peat do not account for temporal variation over the plantation cycle and only consider CO2 emissions. Here, we present direct measurements of GHGs emitted during the conversion from peat swamp forest to oil palm plantation, accounting for CH4 and N2O as well as CO2. Our results demonstrate that emissions factors for converted peat swamp forest is in the range 70-117 t CO2 eq ha-1 yr-1 (95% confidence interval, CI), with CO2 and N2O responsible for ca. 60 and ca. 40% of this value, respectively. These GHG emissions suggest that conversion of Southeast Asian peat swamp forest is contributing between 16.6 and 27.9% (95% CI) of combined total national GHG emissions from Malaysia and Indonesia or 0.44 and 0.74% (95% CI) of annual global emissions
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Evidence for atmospheric control of sea-ice motion through Nares Strait
Satellite observations of ice motion are combined with model estimates of lowâlevel winds and surface wind stress to provide evidence for atmospheric control of seaâice motion through Nares Strait, between Ellesmere Island and Greenland, during two periods in 2004. The results suggest that ice flux through the strait, and its shutdown through the formation of a landfast ice mass in the strait, can be controlled by wind stress and atmospheric cooling. Analysis of the model results during these two periods also suggest that the intense, lowâlevel, alongâstrait winds are strongly ageostrophic, and may be usefully estimated from pressure differences along the Strait
Legal issues in clouds: towards a risk inventory.
Cloud computing technologies have reached a high level of development, yet a number of obstacles still exist that must be overcome before widespread commercial adoption can become a reality. In a cloud environment, end users requesting services and cloud providers negotiate service-level agreements (SLAs) that provide explicit statements of all expectations and obligations of the participants. If cloud computing is to experience widespread commercial adoption, then incorporating risk assessment techniques is essential during SLA negotiation and service operation. This article focuses on the legal issues surrounding risk assessment in cloud computing. Specifically, it analyses risk regarding data protection and security, and presents the requirements of an inherent risk inventory. The usefulness of such a risk inventory is described in the context of the OPTIMIS project
Evaluation of a microfluidic atmospheric-pressure plasma reactor for water treatment
A dielectric barrier discharge (DBD) microfluidic plasma reactor, operated at atmospheric pressure, was studied for its potential to treat organic contaminants in water. The proposed microfluidic plasma reactor (MPR) allows in situ production of plasma in a continuous flow, operated under atmospheric pressure, for plasma-based water treatment. The MPR operates with glass as the dielectric barrier, where plasma is generated in the continuous gas flow stream of a gas-liquid two-phase annular flow regime in the microchannels. The microchannels have dimensions of 100 ”m depth, 250 ”m width and the plasma is generated in an approximately 21 cm length of microchannel arranged in a serpentine pattern. Methylene blue (MB) in solution was used as a model organic to investigate its degradation by plasma generated in the microchannels. The influence of discharge time, residence time and gas sources, i.e. air, argon and oxygen, on MB degradation was studied. The percentage degradation increased with lower liquid flow rates, with maximum degradation of MB achieved at a liquid flow rate of 35 ”L/min and inlet gas pressure of 1 bar using oxygen as the working gas. Liquid chromatography/mass spectrometry analysis of the MB solution after treatment suggests degradation through fragmentation of MB. It is intended that the device will be used as proof of concept to introduce plasma technology as an advanced oxidation process for water treatment, with the potential to achieve total mineralization of dissolved organic materials and microbial inactivation, replacing water treatment chemicals and consumables
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