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

Kuujjua River Arctic Char: Monitoring Stock Trends Using Catches from an Under-Ice Subsistence Fishery, Victoria Island, Northwest Territories, Canada, 1991 – 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 1996–2002 and 568 (SD 274) in 2003–09, or roughly 40% and 20% of the harvest levels estimated for 1971–78 (2900, SD 842) and 1988–92 (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 pêche hivernale, un programme de surveillance standardisé axé sur les récoltes a été réalisé quant à la pêche de subsistance principale d’omble chevalier (Salvelinus alpinus) sur la rivière Kuujjua. Ce programme a été mis en oeuvre à la lumière des inquiétudes exprimées par les résidents d’Ulukhaktok qui affirmaient que le nombre d’ombles chevaliers diminuait, tout comme leur taille. De 1996 à 2002, la récolte moyenne d’ombles chevaliers atteignait 1 225 (SD 262) annuellement, tandis que de 2003 à 2009, la récolte moyenne annuelle s’élevait à 568 (SD de 274), soit environ 40 % et 20 % des récoltes évaluées pour les années 1971 à 1978 (2 900, SD de 842) et les années 1988 à 1992(2 943, SD de 1 072). Il n’existait pas de lien statistique entre la taille de la récolte annuelle (le nombre de poissons) et la valeur de la capture par unité d’effort (CPUE) moyenne annuelle correspondante (R2 = 0,0141, p = 0,761). L’omble chevalier était pleinement recruté à la pêche à l’âge de neuf ans, avec 82,4 % de la capture échantillonnée (n = 3288) variant entre huit et 12 ans, et composée presque exclusivement (99 %) d’adultes non encore reproducteurs. Au fil des séries, aucune tendance temporelle n’a été décelée (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 à la fourche (593 mm, SD 78,1) ou de l’âge moyen (9,9 ans, SD 2,0). Le taux de mortalité annuel indiquait une tendance à la baisse à la fois faible mais importante au cours des séries (R2 = 0,354), et il n’y 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 corrélation a été établie entre l’écart des indices somatiques annuels moyens et le moment du dégagement de la glace de mer au printemps (R2 = 0,474, p = 0,002), probablement parce que la qualité ou la quantité de proies, ou les deux, est plus élevée au cours des étés qui suivent une prolifération printanière hâtive dans l’environnement marin. Ensemble, l’absence de tendances temporelles relatives à la CPUE, à la longueur à la fourche et à l’âge du poisson récolté et l’amélioration apparente de la survie (mortalité plus faible) suggèrent que le stock était stable aux niveaux de récolte observés pendant la période de surveillance. Par ailleurs, il se pourrait que le stock connaisse une valeur d’adaptation quelque peu améliorée, ce qui est attribuable aux changements caractérisant la productivité environnementale et semble lié, tout au moins en partie, au moment de la débâcle du printemps dans l’est du golfe Amundsen

A microfluidic atmospheric-pressure plasma reactor for water treatment

A dielectric barrier discharge microfluidic plasma reactor, operated at atmospheric pressure, was studied for its potential to treat organic contaminants in water. Microfluidic technology represents a compelling approach for plasma-based water treatment due to inherent characteristics such as a large surface-area-to-volume ratio and flow control, in inexpensive and portable devices. The microfluidic device in this work incorporated a dielectric barrier discharge generated in a continuous gas flow stream of a two-phase annular flow regime in the microchannels of the device. Methylene blue in solution was used to investigate plasma induced degradation of dissolved organic compounds within the microfluidic device. The relative degradation rates of methylene blue were influenced by the residence time of the sample solution in the discharge zone, type of gas applied, channel depth and flow rate. Increasing the residence time inside the plasma region led to higher levels of degradation. Oxygen was found to be the most effective gas, with the spectra obtained using Liquid Chromatography-Mass Spectroscopy indicating the most significant degradation. By reducing the channel depth from 100 to 50 µm, the best results were obtained, achieving a greater than 97% level of methylene blue degradation. The microfluidic system presented here demonstrates proof-of-concept that plasma technology can be utilised as an advanced oxidation process for water treatment, with the potential to eliminate water treatment consumables such as filters and disinfectants

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

Seasonal Movements and Diving of Ringed Seals, Pusa hispida, in the Western Canadian Arctic, 1999–2001 and 2010–11

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 – 352). Adult and subadult ringed seals traveled considerable distances throughout the open water period (mean = 5844 km, range = 1232 – 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 – 2000 and 2010 – 11) and least restricted during the winter (2000 – 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 été déployés sur 17 phoques annelés au début des étés 1999, 2000 et 2010 près de la collectivité inuvialuite d’Ulukhaktok, dans les Territoires du Nord-Ouest, au Canada. L’objectif principal consistait à étudier les déplacements et les comportements de plongée des phoques annelés des régions du détroit de Prince-Albert (DPA) et de la partie est du golfe Amundsen (EGA) en fonction de la saison, du sexe et de la classe d’âge. Les étiquettes ont donné des résultats valables dans le cas de 16 des 17 phoques étiquetés, les périodes moyennes de pistage ayant atteint 256 jours (SD 69, étendue : 134 – 352). Les phoques annelés adultes et jeunes adultes parcouraient des distances considérables pendant la période des eaux libres (moyenne = 5 844 km, étendue = 1 232 – 9 473 km), dans de vastes domaines vitaux au cours de la saison. Les pourcentages du volume des contours de 90 (90 PVC) s’établissaient en moyenne à 122 854 km2 pour les jeunes adultes, à 76 658 km2 pour les femelles adultes et à 21 649 km2 pour les mâles adultes. Dans l’ensemble, les adultes ont passé 69,5 % des journées observées en eaux libres en mode d’alimentation et de résidence, et 22,8 % en mode de déplacement. La majorité (75 %) du temps total observé en mode d’alimentation et de résidence était dans le DPA et l’EGA. Onze adultes sur 12 se sont aventurés en dehors du DPA et de l’EGA pour atteindre des endroits éloignés, dont le détroit du Prince-de-Galles (7 phoques), le détroit du Vicomte de Melville (6), l’anse Mintot (4), l’ouest du golfe Amundsen (4) et six autres zones. Pendant la saison des eaux libres, les jeunes adultes ont passé 36,8 % du temps en mode de déplacement et 51,4 % du temps en mode d’alimentation ou de résidence, également principalement dans le DPG et l’EGA (61 %), mais ils se sont tous rendus dans des zones éloignées, huit en tout. Durant l’hiver, toutes les femelles adultes étiquetées, cinq mâles adultes sur sept et trois jeunes adultes sur quatre sont revenus dans le DPA et l’EGA pour occuper des domaines vitaux hivernaux qui correspondaient, en moyenne, à 15 % de la taille du domaine vital en eaux libres (étendues moyennes des domaines hivernaux = 1 299 km2 pour les mâles adultes, 3 599 km2 pour les femelles adultes et 30 499 km2 pour les jeunes adultes). La taille moyenne des domaines vitaux hivernaux a varié en fonction d’un facteur de 10 au cours des trois hivers à l’étude. Le déplacement des phoques était plus restreint pendant les hivers où la glace était rapide (1999-2000 et 2010-2011) et moins restreint pendant l’hiver (2000-2001) où la glace rapide ne s’est pas formée dans l’EGA. L’hiver, les femelles adultes faisaient plus de plongées longues et profondes que les mâles adultes ou les jeunes adultes

Arrangement of sympathetic fibers within the human common peroneal nerve: Implications for microneurography

Recently, interest has grown in the firing patterns of individual or multiunit action potential firing patterns in human muscle sympathetic nerve recordings using microneurography. Little is known, however, about sympathetic fiber distribution in human lower limb nerves that will affect the multiunit recordings. Therefore, the purpose of this study was to examine the sympathetic fiber distribution within the human common peroneal nerve using immunohistochemical techniques (tyrosine hydroxylase, avidin-biotin complex technique). Five-micrometer transverse and 10-μm longitudinal sections, fixed in formaldehyde, were obtained from the peroneal nerve that had been harvested from three human cadavers (83 ± 11 yr) within 24 h of death. Samples of rat adrenal gland and brain served as controls. Sympathetic fiber arrangement varied between left and right nerves of the same donor, and between donors. However, in general, sympathetic fibers were dispersed throughout ∼25-38 fascicles of the peroneal nerve. The fibers were grouped in bundles of ∼2-44 axons or expressed individually throughout the fascicles, and the distribution was skewed toward smaller bundles with median and interquartile ratio values of 5 and 1 axons/bundle, respectively. These findings confirm the bundled organization of sympathetic axons within the peroneal nerve and provide the anatomical basis for outcomes in microneurographic studies. Copyright © 2013 the American Physiological Society

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

High heterotrophic CO2 emissions from a Malaysian oil palm plantations during dry-season

Background Tropical peatlands are currently being rapidly cleared and drained for the establishment of oil palm plantations, which threatens their globally significant carbon sequestration capacity. Large-scale land conversion of tropical peatlands is important in the context of greenhouse gas emission factors and sustainable land management. At present, quantification of carbon dioxide losses from tropical peatlands is limited by our understanding of the relative contribution of heterotrophic and autotrophic respiration to net peat surface CO2 emissions. Methods In this study we separated heterotrophic and autotrophic components of peat CO2 losses from two oil palm plantations (one established in ‘2000’ and the other in 1978, then replanted in ‘2006’) using chamber-based emissions sampling along a transect from the rooting to non-rooting zones on a peatland in Selangor, Peninsular Malaysia over the course of three months (June-August, 2014). Collar CO2 measurements were compared with soil temperature and moisture at site and also accompanied by depth profiles assessing peat C and bulk density. Results The soil respiration decreased exponentially with distance from the palm trunks with the sharpest decline found for the plantation with the younger palms. The mean heterotrophic flux was 1244.7 ± SE 149.2 mg m-2h-1 and 663.8 ± SE 102.2 mg m-2h-1 at the 2000 and 2006 plantations, respectively. Autotrophic emissions adjacent to the palm trunks were 944 ± SE 99.7 mg m-2h-1 and 1962 ± SE 246 mg m-2h-1 at the 2000 and 2006 plantations, respectively. Heterotrophic CO2 flux was positively related to peat soil moisture, but not temperature. Total peat C stocks were 60 kg m-2 (down to 1 m depth) and did not vary among plantations of different ages but SOC concentrations declined significantly with depth at both plantations but the decline was sharper in the second generation 2006 plantation. Conclusions The CO2 flux values reported in this study suggest a potential for very high carbon (C) loss from drained tropical peats during the dry season. This is particularly concerning given that more intense dry periods related to climate change are predicted for SE Asia. Taken together, this study highlights the need for careful management of tropical peatlands, and the vulnerability of their carbon storage capability under conditions of drainage