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Kinds of Station Terms modified by Station Selected AbstractsWood distribution in neotropical forested headwater streams of La Selva, Costa RicaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2009Daniel Cadol Abstract Surveys of wood along 30 forested headwater stream reaches in La Selva Biological Station in north-eastern Costa Rica represent the first systematic data reported on wood loads in neotropical streams. For streams with drainage areas of 0·1,8·5 km2 and gradients of 0·2,8%, wood load ranged from 3 to 34·7 m3 wood/100 m channel and 41,612 m3 wood/ha channel. These values are within the range reported for temperate streams. The variables wood diameter/flow depth, stream power, the presence of backflooding, and channel width/depth are consistently selected as significant predictors by statistical models for wood load. These variables explain half to two-thirds of the variability in wood load. These results, along with the spatial distribution of wood with respect to the thalweg, suggest that transport processes exert a greater influence on wood loads than recruitment processes. Wood appears to be more geomorphically effective in altering bed elevations in gravel-bed reaches than in reaches with coarser or finer substrate. Copyright © 2009 John Wiley & Sons, Ltd. [source] Short-term erosion rates from a 7Be inventory balanceEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2003Christopher G. Wilson Abstract Detailed soil erosion studies bene,t from the ability to quantify the magnitude of erosion over time scales appropriate to the process. An inventory balance for 7Be was used to calculate sediment erosion in a 30·73 m2 plot during a series of runoff-producing thunderstorms occurring over three days at the Deep Loess Research Station in Treynor, Iowa, USA. The inventory balance included determination of the pre- and post-storm 7Be inventories in the soil, the atmospheric in,ux of 7Be during the event, and pro,les of the 7Be activity in the soil following the atmospheric deposition. The erosion calculated in the plot using the 7Be inventory balance was 0·058 g cm,2, which is 23 per cent of the annual average erosion determined using 137Cs inventories. The calculated erosion from the mass balance is similar to the 0·059 g cm,2 of erosion estimated from the amount of sediment collected at the outlet of the 6 ha ,eld during the study period and the delivery ratio (0·64). The inventory balance of 7Be provides a new means for evaluating soil erosion over the time period most relevant to quantifying the prediction of erosion from runoff. Copyright © 2003 John Wiley & Sons, Ltd. [source] Temporal coherence of aboveground net primary productivity in mesic grasslandsECOGRAPHY, Issue 3 2008Jana L. Heisler Synchrony in ecological variables over wide geographic areas suggests that large-scale environmental factors drive the structure and function of ecosystems and override more local-scale environmental variation. Described also as coherence, this phenomenon has been documented broadly in the ecological literature and has recently received increasing attention as scientists attempt to quantify the impacts of global changes on organisms and their habitats. Using a mesic grassland site in North America, we assessed coherence in ecosystem function by quantifying similarity in aboveground net primary production (ANPP) dynamics in 48 permanent sampling locations (PSLs) over a 16-yr period. Our primary objective was to characterize coherence across a broad geographic region (with similar ecosystem structure and function), and we hypothesized that precipitation and a similar fire frequency would strengthen coherence between PSLs. All 48 PSLs at our site (Konza Prairie Biological Station, Manhattan, KS, USA; KPBS) were exposed to a similar regional driver of ANPP (precipitation); however, local drivers (including differences in fire frequency and soil depth at different topographic positions) varied strongly among individual PSLs. For the purpose of this assessment, the watershed-level experimental design of KPBS was considered a model, which represented different fire management strategies across the Great Plains Region. Our analyses revealed a site-level (KPBS) coherence in ANPP dynamics of 0.53 for the period of 1984,1999. Annual fire enhanced coherence among PSLs to 0.76, whereas less frequent fire (fire exclusion or a 4-yr fire return interval) failed to further increase coherence beyond that of the KPBS site level. Soil depth also strongly influenced coherence among PSLs with shallow soils at upland sites showing strong coherence across fire regimes and annually burned uplands closely linked to annual precipitation dynamics. The lack of coherence in ecosystem function in PSLs with deep soils and low fire frequencies suggests that conservation and management efforts will need to be more location specific in such areas where biotic interactions may be more important than regional abiotic drivers. [source] A historical record of mercury contamination in southern florida (USA) as inferred from avian feather tissue: Contribution R-09888 of the Journal Series, Florida Agricultural Experiment StationENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2004Peter C. Frederick Abstract During the late 1980s, the upper trophic-level biota of the Everglades (FL, USA) was recognized as being highly contaminated with mercury (Hg). However, the timing and pattern of that increase is poorly known, and no information is available about mercury contam ination in Everglades wildlife prior to 1974. We measured methylmercury concentrations in feathers of white ibises (n = 33), great egrets (n = 7), anhingas (n = 21), and great blue herons (n = 12) from museum specimens collected from 1910 through 1980 and combined them with more recent feather samples collected from live birds (1985,2000, n = 98, 37, 49, and 7, respectively). We found no evidence of contamination of museum samples with inorganic mercuric preservatives (0.01,0.28% of total Hg in feathers). All species showed relatively low concentrations of mercury through the 1970s (<5 ,l/L dry wt for anhingas, ibises, and egrets, <10 ,l/L for herons). Samples from all species taken during the 1990s showed a large and significant increase (4,5X) in MeHg concentration. This evidence suggests that most of the increase in Hg deposition during the 20th century in south Florida occurred during the last two to three decades, which is consistent with information about local source deposition. Contamination levels prior to the 1970s appear to have been associated with normal reproduction in these birds, suggesting partial evidence for a threshold of reproductive impairment. [source] Effect of termites on clay minerals in tropical soils: fungus-growing termites as weathering agentsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2002P. Jouquet Summary Termites of the subfamily Macrotermitinae play an important role in tropical ecosystems: they modify the soil's physical properties and thereby make food available for other organisms. Clay is important in the architecture of Macrotermitinae termite nests, and it has been postulated that termites could modify the mineralogical properties of some clays. We have tested this hypothesis of clay transformation by termites in the laboratory under controlled conditions, using Odontotermes nr. pauperans termite species, one of the main fungus-growing species at Lamto Research Station (Côte d'Ivoire). Soil handled by termites in nest building was saturated with SrCl2, glycol or KCl and afterwards heated at 250°C for X-ray diffraction analyses. Termite handling led to an increase in the expandable layers of the component clay minerals. Heating and saturation by potassium of modified clays did not close the newly formed expandable clay layers. However, differences occurred between parts of the constructions built by termites, and the clays can be ranked according to their degree of alteration in the following order: unhandled soils < galleries < chamber walls. Consequently, termites can be seen as weathering agents of clay minerals, as previously shown for micro-organisms and plants. [source] Evidence for plant viruses in the region of Argentina Islands, AntarcticaFEMS MICROBIOLOGY ECOLOGY, Issue 2 2007Valery Polischuk Abstract This work focused on the assessment of plant virus occurrence among primitive and higher plants in the Antarctic region. Sampling occurred during two seasons (2004/5 and 2005/6) at the Ukrainian Antarctic Station ,Academician Vernadskiy' positioned on Argentina Islands. Collected plant samples of four moss genera (Polytrichum, Plagiatecium, Sanionia and Barbilophozia) and one higher monocot plant species, Deschampsia antarctica, were further subjected to enzyme-linked immunosorbent assay to test for the presence of common plant viruses. Surprisingly, samples of Barbilophozia and Polytrichum mosses were found to contain antigens of viruses from the genus Tobamovirus, Tobacco mosaic virus and Cucumber green mottle mosaic virus, which normally parasitize angiosperms. By contrast, samples of the monocot Deschampsia antarctica were positive for viruses typically infecting dicots: Cucumber green mottle mosaic virus, Cucumber mosaic virus and Tomato spotted wilt virus. Serological data for Deschampsia antarctica were supported in part by transmission electron microscopy observations and bioassay results. The results demonstrate comparatively high diversity of plant viruses detected in Antarctica; the results also raise questions of virus specificity and host susceptibility, as the detected viruses normally infect dicotyledonous plants. However, the means of plant virus emergence in the region remain elusive and are discussed. [source] Distribution and growth of benthic macroinvertebrates among different patch types of the littoral zones of two arctic lakesFRESHWATER BIOLOGY, Issue 12 2006STEVEN R. BEATY Summary 1. To evaluate the effect of habitat patch heterogeneity on abundance and growth of macroinvertebrates in arctic lakes, macroinvertebrate abundance, individual biomass, and potential food resources were studied in three patch types in two arctic lakes on the Alaskan North Slope near the Toolik Lake Field Station. An experiment was conducted to determine which sediment patch type supported higher growth rates for Chironomus sp., a commonly occurring macroinvertebrate. 2. Potential organic matter (OM) resources were significantly higher in both rock and macrophyte patches than in open-mud patches. Total macroinvertebrate densities in both lakes were highest in rock patches, intermediate in macrophytes and lowest in open-mud. The open-mud patches also had lower species richness compared with other patch types. Additionally, individual biomass for one clam species and two chironomid species was significantly greater in rock patches than in open-mud. 3. In a laboratory experiment, Chironomus showed two to three times greater mass increase in sediments from macrophyte and rock patches than from open-mud patches. Rock and macrophyte experimental sediments had at least 1.5 × the percentage OM as open-mud sediments. 4. Chlorophyll a appeared to be the best predictor for invertebrate abundances across all patch types measured, whereas OM content appeared to be the variable most closely associated with Chironomus growth. 5. Our results combined with previous studies show that the relationships between macroinvertebrate community structure, individual growth, and habitat heterogeneity are complex, reflecting the interaction of multiple resources, and biotic interactions, such as the presence or absence of a selective vertebrate predator (lake trout, Salvelinus namaycush). [source] Beyond stratigraphic noise: Unraveling the evolution of stratified assemblages in faunalturbated sitesGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 6 2006Eugène Morin This study explores the stratigraphic evolution of archaeological assemblages in faunalturbated sites. These sites are sometimes described as having limited archaeological value because of varying degrees of occupation mixing. It is argued here that the vertical distribution of assemblages is predictable in faunalturbated contexts. Understanding this vertical evolution may lead to a better assessment of the archaeological potential of a cultural sequence. In faunalturbated soils, the stratigraphic evolution of the assemblages is largely dictated by faunal activity. Tunneling by small animals tend to "sink" cultural remains through the deposits. Although objects sink at a relatively fast pace near the surface, the process slows down as the objects reach the bottom of the biomantle where the sediments are more compact. This process affects the shape of the artifact vertical distribution. The analysis of a multicomponent site from southern Québec is used to model how assemblages may evolve temporally in faunalturbated settings. At Station 3-avant, the stratigraphic distribution of the cultural remains appears to evolve from an upward-skewed distribution to a bottom-skewed distribution through time. This evolution is interpreted to result from the fact that objects are often too large and/or heavy to be moved upward by the pedofauna. In situations in which this stage of stratigraphic evolution is not yet reached, enough information about temporal successions may be retained for the site to be useful for investigating diachronic change. This may prove invaluable in regions in which faunalturbated sequences are common. © 2006 Wiley Periodicals, Inc. [source] Design approach for the hybrid underground station at Union Suare/Market Street in San Francisco.GEOMECHANICS AND TUNNELLING, Issue 4 2009Entwurfskonzept für eine hybride U-Bahnstation Union Square/Market Street in San Francisco Abstract The new Central Subway extension through downtown San Francisco consists of three underground stations and 2.7 km TBMdriven twin tunnel. This paper provides a description of the preliminary analyses and design of the ground support and final lining for the Union Square\Market Street Station (UMS) along Stockton Street. This station will serve the Union Square Shopping District and connect to the BART Powell Street Station. Due to shortage of space above ground and to minimize surface disruption, the UMS station design requires a complex hybrid method consisting of a 20 m deep braced cut-and-cover box with a mined enlargement bulb below it with a height of 9.3 m and a width of 17.8 m. The majority of the UMS station will be excavated in saturated alluvial deposits. Undifferentiated old bay deposits will be encountered in the invert, underlain by dense marine sands. The groundwater varies from 5 to 10 m below ground level, so uplift of the combined bulb/box structure has to be taken into account. The Finite Element (FE) analysis of the UMS station cavern reflects the separate construction phases of the station platform box and the bulb to account for soil-structure interaction and load-sharing effects. FE analyses are used to estimate support requirements including ground improvement and to predict surface settlements. Die Erweiterung der Central Subway durch die Innenstadt von San Francisco beinhaltet drei Stationsbauwerke und 2,7 km maschinell vorgetriebene Doppelröhrentunnel. In diesem Artikel erfolgt eine Beschreibung der Voruntersuchungen und Vorbemessung der Stützmaßnahmen sowie der Innenschale der Union Square\Market Street Station (UMS) im Verlauf der Stockton Street. Diese Station soll dem Union Square Shopping Distrikt dienen und zur BART Powell Street Station verbinden. Aufgrund der beengten Platzverhältnisse und zur Minimierung der Beeinträchtigung der Oberfläche ist ein "hybrides" Konzept der UMS-Station erforderlich. Dieses besteht aus einer 20 m tiefen ausgesteiften Baugrube (Box) und einer darunterliegenden bergmännisch hergestellten Kaverne (Bulb) mit 9,3 m Höhe und 17,8 m Breite. Der Großteil der UMS-Station befindet sich in gesättigten alluvialen Ablagerungen. Undifferenziert werden alte Bucht-Ablagerungen und dichte marine Sande in der Sohle vorgefunden. Der Grundwasserspiegel variiert in einer Teufe zwischen 5 bis 10 m unter der Oberfläche, aus diesem Grund ist der Auftrieb des kombinierten Bauwerks bestehend aus Bulb und Box zu berücksichtigen. In Finite Element (FE) Berechnungen der UMS-Station werden die einzelnen Bauphasen des Stationsbauwerks, sowohl von Box als auch Bulb, modelliert, um die Wechselwirkungen von Baugrund-Bauwerk und die jeweiligen Lastumlagerungen zu berücksichtigen. Mittels FE-Berechnungen werden schließlich die notwendigen Stützmaßnahmen , diese beinhalten auch Bodenverbesserungsmaßnahmen , und die Oberflächensetzungen festgelegt. [source] Geodetic observations of ice flow velocities over the southern part of subglacial Lake Vostok, Antarctica, and their glaciological implicationsGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2006Jens Wendt SUMMARY In the austral summer seasons 2001/02 and 2002/03, Global Positioning System (GPS) data were collected in the vicinity of Vostok Station to determine ice flow velocities over Lake Vostok. Ten GPS sites are located within a radius of 30 km around Vostok Station on floating ice as well as on grounded ice to the east and to the west of the lake. Additionally, a local deformation network around the ice core drilling site 5G-1 was installed. The derived ice flow velocity for Vostok Station is 2.00 m a,1± 0.01 m a,1. Along the flowline of Vostok Station an extension rate of about 10,5 a,1 (equivalent to 1 cm km,1 a,1) was determined. This significant velocity gradient results in a new estimate of 28 700 years for the transit time of an ice particle along the Vostok flowline from the bedrock ridge in the southwest of the lake to the eastern shoreline. With these lower velocities compared to earlier studies and, hence, larger transit times the basal accretion rate is estimated to be 4 mm a,1 along a portion of the Vostok flowline. An assessment of the local accretion rate at Vostok Station using the observed geodetic quantities yields an accretion rate in the same order of magnitude. Furthermore, the comparison of our geodetic observations with results inferred from ice-penetrating radar data indicates that the ice flow may not have changed significantly for several thousand years. [source] The effect of temperature and daylength on heading in tetraploid cultivars of rhodesgrass (Chloris gayana Kunth)GRASSLAND SCIENCE, Issue 4 2005Isao Tarumoto Abstract The present study was conducted to clarify the effect of temperature and daylength on heading in tetraploid cultivars of rhodesgrass (Chloris gayana Kunth). Five cultivars, Tochiraku-kei (2,), Fords Katambora (2,), Callide (4,), Masaba (4,) and Pokot (4,), were planted on three dates at 1-month intervals (4 May, 4 June and 4 July) in three of the Ministry of Agriculture, Forestry and Fisheries research institutions in Ishigaki (Tropical Agriculture Research Center), Nishigoshi (Kyushu National Agricultural Experiment Station) and Nishinasuno (National Grassland Research Institute) in 1978. Three tetraploid cultivars were planted on three dates at 1-month intervals (4 May, 4 June and 4 July) under four daylength-treatments of natural daylength (ND), 12 h daylength [12 h], ND/12 h and 12 h/ND, and changed daylength at the eighth leaf stage, in Nishinasuno in 1978. Under natural daylength, although heading was not observed for Masaba and Pokot, heading was observed in all plots for Tochiraku-kei, Fords Katambora and Callide, and their days to heading (DH) linearly decreased with increases in daily mean temperature (DMT). The result indicated that, under natural daylength in summer, temperature was a major factor in determining DH in tetraploid Callide, which was the same as in diploid rhodesgrass cultivars. Callide reached heading under all four daylength treatments. However, Masaba and Pokot reached heading only under 12 h and ND/12 h treatments, suggesting that Masaba and Pokot have qualitative sensitivity to photoperiods that operate after the ninth leaf stage. These findings would be useful in tetraploid rhodesgrass for estimating foliage harvesting time in the field and for conducting cross-pollination in a greenhouse during winter. [source] Feeding area specialization of chick-rearing Adélie Penguins Pygoscelis adeliae in a fast sea-ice areaIBIS, Issue 4 2003Yutaka Watanuki Individual feeding area specialization has been reported for several seabird species. Researchers suspect that this behaviour results in feeding and/or reproductive advantages. Adélie Penguins Pygoscelis adeliae feed in small predictable open waters in a fast sea-ice area near Syowa Station, Antarctica. Their feeding sites were determined by radiotracking both members of 20 pairs rearing chicks. Twenty-five birds repeatedly fed in distinct areas more frequently than expected by chance, while the remaining 15 birds had no significant feeding area specialization. Birds seemed to feed at sites that were closer to their most recent feeding sites than they were to earlier feeding sites. Variation in specialized area, degree of feeding area fidelity and distance to feeding sites had no significant effect on the number of feeds that a bird brought to chicks per day. Neither did the estimated mass of feeds brought per day per pair depend on feeding area specialization. [source] Assessment of the cost and accuracy of the generalized FEMINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 2 2007Theofanis Strouboulis Abstract In this paper, we address the cost versus accuracy capabilities for the generalized FEM (GFEM) which was developed in (Comput. Methods Appl. Mech. Eng. 2003; 192:3109,3161, Int. J. Numer. Meth. Engng 2004; 60:1639,1672, Ph.D. Thesis, Texas A&M University, College Station, TX, August 2003 (Advisor: T. Strouboulis)), and also the construction of two-sided a posteriori error estimates, which can be used to assess the achieved accuracy at all levels of the method. Copyright © 2006 John Wiley & Sons, Ltd. [source] Changes in spring weather conditions and atmospheric circulation in Estonia (1955,95)INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2003Sirje Keevallik Abstract An analysis has been undertaken at Tiirikoja Meteorological Station to investigate changes in the main weather elements in late winter and spring during the period 1955,95. The relationship between these changes and the trends in the atmospheric circulation above Estonia have also been analysed. The latter was estimated from wind speed and direction data recorded at Tallinn Aerological Station at two isobaric levels (500 and 850 hPa). These data permitted the analysts to calculate zonal and meridional components of wind velocity at both levels. Linear trends were fitted to time series of monthly averages of all parameters under consideration. The results indicate that significant changes in meteorological parameters took place in March. These changes are statistically related to the changes in the average airflow in the free atmosphere above Estonia. In March the wind speed at the 500 and 850 hPa isobaric levels increased and the average airflow turned from WNW or NW to SW or WSW. Such changes in the atmospheric circulation can only partly be attributed to the intensification of the North Atlantic oscillation. Copyright © 2003 Royal Meteorological Society [source] An economic and environmental assessment of biomass utilization in lignite-fired power plants of GreeceINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2006P. Grammelis Abstract The environmental and socio-economic impacts of biomass utilization by co-firing with brown coal in an existing thermoelectric unit in Greece or through its pure combustion in a new plant were studied and evaluated in this work. The 125 MWe lignite-fired power plant in Ptolemais Power Station (Western Macedonia) was used as reference system. The environmental benefits of the alternative biomass exploitation options were quantified based on the life cycle assessment methodology, as established by SETAC, while the BIOSEM technique was used to carry out socio-economic calculations. The obtained results showed clear environmental benefits of both biomass utilization alternatives in comparison with the reference system. In addition, co-firing biomass with lignite in an existing unit outperforms the combustion of biomass exclusively in a new plant, since it exhibits a better environmental performance and it is a low risk investment with immediate benefits. A biomass combustion unit requires a considerably higher capital investment and its benefits are more evident in the long run. Copyright © 2005 John Wiley & Sons, Ltd. [source] Estimation of solar radiation parameters for Izmir, TurkeyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2002K. Ulgen Abstract In this study, the solar radiation parameters (global and diffuse solar radiation) are correlated with respect to ambient temperatures in the fifth-order polynomial form for Izmir in Turkey. Experimental data were measured in the Solar-Meteorological Station of Solar Energy Institute in Ege University over a 5-yr period, 1994,1998. The ratios of the total daily diffuse to global radiation intensities for each month range from 0.38 to 0.45 averaged for the same period, with an average value of 0.41. It can be concluded that the present models predict the solar radiation parameters reasonably well with the correlation coefficients over 0.95 for the projections. Copyright © 2002 John Wiley & Sons, Ltd. [source] Determination of Weibull parameters for wind energy analysis of ,zmir, TurkeyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 6 2002K. Ulgen Abstract In this study, the two Weibull parameters of the wind speed distribution function, the shape parameter k (dimensionless) and the scale parameter c (ms,1), were computed from the wind speed data for ,zmir. Wind data, consisting of hourly wind speed records over a 5-year period, 1995,1999, were measured in the Solar/Wind-Meteorological Station of the Solar Energy Institute at Ege University. Based on the experimental data, it was found that the numerical values of both Weibull parameters (k and c) for ,zmir vary over a wide range. The yearly values of k range from 1.378 to 1.634 with a mean value of 1.552, while those of c are in the range of 2.956,3.444 with a mean value of 3.222. The average seasonal Weibull distributions for ,zmir are also given. The wind speed distributions are represented by Weibull distribution and also by Rayleigh distribution, with a special case of the Weibull distribution for k=2. As a result, the Weibull distribution is found to be suitable to represent the actual probability of wind speed data for ,zmir (at annual average wind speeds up to 3 ms,1). Copyright © 2002 John Wiley & Sons, Ltd. [source] Comparison of solar radiation correlations for ,zmir, TurkeyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2002K. Ulgen Abstract In this study, empirical correlations are developed to estimate the monthly average daily global solar radiation on a horizontal surface (H) for the city of ,zmir in Turkey. Experimental data were measured in the Solar,Meteorological Station of the Solar Energy Institute at Ege University. The present models are then compared with the 25 models available in the literature for calculating H based on the main percentage error, root mean error, the main bias error, and correlation coefficient. It can be concluded that the present models predict the values of H for ,zmir better than other available models. Copyright © 2002 John Wiley & Sons, Ltd. [source] Control of the Aero-Electric Power Station,an exciting QFT application for the 21st centuryINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 7 2003Per-Olof Gutman Abstract The Aero-Electric Power Station is the ultimate solar power station, utilizing the dry, hot air of Earth's desert zones. By spraying water at the top of e.g. a 1200 m tall chimney with a diameter of 400 m, the air is cooled by evaporation and flows downwards through turbines at the bottom, generating 380 MW of net electric power. The Aero-Electric Power Station is still in the planning stage, and this paper belongs to a long series of feasibility studies. The current ,truth' model of the Aero-Electric Power Station is a one-dimensional partial differential equation model. The external slowly changing weather, defined as the mean air pressures, temperatures and humidity at the top and bottom of the tower, determines the optimal operating point, i.e. the optimal water spray flow and turbine velocity that give the largest net power. The gross power produced by the turbine is partly delivered to the grid and partly to pump sea water to spray water reservoirs. The reservoirs make it possible to use the pumping power and the spray flow rate as control. Wind changes cause significant deviations from the mean external air pressures, requiring closed loop regulation to keep the rotor velocity constant. The Aero-Electric Power Station may be modelled as an uncertain, unstable irrational transfer function, with two disturbances (external air pressure deviations at top and bottom), two control variables (turbine power and spray flow), and one output (rotor velocity), without a cascaded structure, giving rise to a robust load sharing control problem. A robust linear feedback regulator is designed by QFT, in such a way that the load of regulation is shared between the two control inputs. A closed loop step response simulation for one operating condition, using the ,truth' model, demonstrates the design. Copyright © 2003 John Wiley & Sons, Ltd. [source] Feeding and anhydrobiosis in bdelloid rotifers: a preparatory study for an experiment aboard the International Space StationINVERTEBRATE BIOLOGY, Issue 4 2004Claudia Ricci Abstract. Here we report the effect of food concentration on the recovery from anhydrobiosis of a bdelloid rotifer, Macrotrachela quadricornifera. Cohorts were either starved, or fed high or low concentrations of food, before being dried and their subsequent recovery rates determined. The rotifers starved for 3 d before anhydrobiosis recovered in significantly higher proportion, and those fed lower food concentration recovered better than those fed higher food concentration. In addition, starvation did not decrease the recovery of other bdelloid species (Philodina roseola and Adineta sp. 1) which were either fed or starved before anhydrobiosis. These results suggest that a successful recovery from anhydrobiosis is not dependent on prior resource level supplied to the bdelloids. However, the lack of resources might not be the only factor in a successful recovery from anhydrobiosis. Observations using scanning electron microscopy of fed individuals of M. quadricornifera entering anhydrobiosis showed that some food remained in the digestive tract. Thus, we propose that the negative effect of rich food may be due to a purely mechanical effect and may be interfering with a proper folding of the rotifer body at the onset of anhydrobiosis. This contribution results from studies carried out in preparation for biological experiments scheduled on the International Space Station (ISS). [source] An in situ method for the study of strain broadening using synchrotron X-ray diffractionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2007C. C. Tang A tensonometer for stretching metal foils has been constructed for the study of strain broadening in X-ray diffraction line profiles. This device, which is designed for use on powder diffractometers and was tested on Station 2.3 at Daresbury Laboratory, allows in situ measurements to be performed on samples under stress. It can be used for data collection in either transmission or reflection modes using either symmetric or asymmetric diffraction geometries. As a test case, measurements were carried out on an 18,µm-thick copper foil experiencing strain levels of up to 5% using both symmetric reflection and symmetric transmission diffraction. All the diffraction profiles displayed peak broadening and asymmetry which increased with strain. The measured profiles were analysed by the fundamental-parameters approach using the TOPAS peak-fitting software. All the observed broadened profiles were modelled by convoluting a refineable diffraction profile, representing the dislocation and crystallite size broadening, with a fixed instrumental profile predetermined using high-quality LaB6 reference powder. The deconvolution process yielded `pure' sample integral breadths and asymmetry results which displayed a strong dependence on applied strain and increased almost linearly with applied strain. Assuming crystallite size broadening in combination with dislocation broadening arising from f.c.c. a/2,110,{111} dislocations, the variation of mechanical property with strain has been extracted. The observation of both peak asymmetry and broadening has been interpreted as a manifestation of a cellular structure with cell walls and cell interiors possessing high and low dislocation densities. [source] Characterization of enterococci populations collected from a subsurface flow constructed wetlandJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2010A.K. Graves Abstract Aims:, The aim of this study was to identify and characterize the population of Enterococcus sp. in domestic wastewater as it flows through a constructed wetland. Methods and Results:, Four hundred and eighty-four Enterococcus isolates were collected from the inlet, various sites within and from the outlet of a plastic lined constructed wetland in College Station, TX. The wetland treated septic tank effluent that passed sequentially through two 1·89 m3 septic tanks and a 1·89 m3 pump tank allowing 48 l doses at a 24 l min,1 rate. The Enterococcus isolates were identified to species using the commercial Biolog system. The 484 Enterococcus isolates were comprised of ten different species, including Enterococcus faecalis (30·6%), Enterococcus pseudoavium (24·0%), Enterococcus casseliflavus (12·8%), Enterococcus faecium (11·2%), Enterococcus mundtii (7·9%), Enterococcus gallinarum (6·2%), Enterococcus dispar (3·7%), Enterococcus hirae (2·1%), Enterococcus durans and Enterococcus flavescens both 0·8%. Of the 88 isolates collected from the inlet, only 9·1% of the isolates were identified as Ent. faecalis and Ent. pseudoavium (36·4%) was identified as the predominant species. Whereas of the 74 isolates collected from the outlet, the predominant species were identified as Ent. faecalis (29·7%). Species identification varied among sites within the wetland, but often Ent. faecalis was the predominant species. Conclusions:, Our data suggest that while Ent. faecalis is the predominant species of Enterococcus found in domestic wastewater, the populations may shift during treatment as the wastewater flows through the constructed wetland. Significance and Impact of the Study:, We found that shifts in Enterococcus species composition occurred during domestic wastewater treatment. This has implications for the identification of faecal pollution based on the presence of specific bacterial types associated with domestic wastewater. [source] Spatial variations in the composition and abundance of zooplankton in the Bahir Dar Gulf of Lake Tana, EthiopiaAFRICAN JOURNAL OF ECOLOGY, Issue 1 2010Tunde Ohiokhioya Thadeus Imoobe Abstract The zooplankton in the littoral and open water zones of Bahir Dar Gulf, Lake Tana, collected in June and July 2007, were investigated using basic statistical measurement of diversity indices and one way analysis of variance to characterize the zooplankton fauna, with respect to its composition, abundance and spatial distribution patterns. The zooplankton composition was typical of a tropical freshwater lake, with a total of 44 species made up of sixteen rotifers, sixteen c1adocerans and twelve copepods and their developing stages in the following order of dominance; Rotifera > Cladocera > Cylopoida > Calanoida. Variation in spatial distribution was noticeable, the abundance of zooplankton was significantly higher (P < 0.05) at the littoral zone (Stations 2 and 3) than the open water (Station 1) as a result of the preponderance of the small-bodied nauplii stages, small rotifers and c1adocerans particularly Bosmina longirostris. Species richness, evenness, and diversity also increased as abundance increased in the littoral zones of the lake. The rotifers, particularly the brachionids Keratella and Brachionus spp., which are considered good indicators of lake trophic status constituted the dominant zooplankton group in terms of abundance and diversity, thus indicating that the lake has a high fisheries potential. Résumé Le zooplancton des berges et des eaux ouvertes du golfe de Bahir Dar, récolté en juin et juillet 2007 dans le lac Tana, a étéétudié en utilisant des indices de mesures statistiques de base et une analyse de la variance à une voie, pour caractériser la faune du zooplancton, tant au point de vue de la composition que de l'abondance et du schéma de distribution spatiale. La composition du zooplancton était typique d'un lac d'eau douce tropical, avec un total de 44 espèces réparties entre 16 rotifères, 16 cladocères et 12 copépodes à différents stades de développement dans l'ordre de prépondérance qui suit : Rotifères > Cladocères > Cylopoïdes > Calanoïdes. Il y avait une variation notable de la distribution spatiale : l'abondance de zooplancton était significativement plus grande (P < 0.05) dans la zone littorale (Stations 2 et 3) qu'en haute eau (Station 1), suite à la prépondérance des petits corpuscules comme les stades nauplius, les petits rotifères et cladocères, et particulièrement Bosmina longirostris. La richesse en espèces, l'uniformité et la diversité augmentaient aussi en même temps que l'abondance dans les zones littorales du lac. Les rotifères, et particulièrement Keratella et Brachionus spp., qui sont considérés comme de bons indicateurs du statut trophique du lac étaient le groupe de zooplancton dominant en termes d'abondance et de diversité, ce qui indique que le lac a un fort potentiel piscicole. [source] Effect of inhibitory compounds on the anaerobic digestion performance of diluted wastewaters from the alimentary industryJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2009Rafael Camarillo Abstract BACKGROUND: Up to now the effect of inhibitory compounds on the anaerobic digestion performance of urban and industrial wastewaters has been mostly studied in fluidized bed and upflowing anaerobic sludge blanket (UASB) bioreactors but not in upflow packed-bed biodigesters. RESULTS: In this paper, response surface methodology (RSM) was used to quantify the effect of various inhibitory compounds (olive oil, ethanol and phenol) on chemical oxygen demand (COD) removal and biogas production rate from synthetic solutions and real industrial wastewaters by anaerobic digestion. The synthetic solutions possessed the same composition in these inhibitory compounds as diluted effluents from olive oil mill and winery industries. The process was performed in a laboratory scale digester containing anaerobic sludge from the Urban Reclamation Station of Toledo (Spain). The comparison of both individual factors and interactions between factors showed that the addition of olive oil at moderate concentrations (up to 0.5% w/w) did not change the performance of the process in comparison with that observed when feeding to the system a model solution (51.5% COD removal, 0.65 L biogas day,1). However, low concentrations of ethanol or phenol (250 and 150 mg L,1, respectively) almost completely inhibited the methanogenic phase. Moreover, a strong interaction between ethanol and phenol concentrations on COD removal was observed. CONCLUSION: The experimental results showed quantitatively the importance of some inhibitory compounds on anaerobic treatment of both synthetic solutions and real wastewaters from olive oil mill and winery industries. Inhibitory effects are closely related to both the organic loads and the anaerobic bioreactor used. Copyright © 2009 Society of Chemical Industry [source] The genetic stock structure of larval and juvenile winter flounder larvae in Connecticut waters of eastern Long Island Sound and estimations of larval entrainmentJOURNAL OF FISH BIOLOGY, Issue 1 2004J. F. Crivello Variability at six microsatellite loci was examined among 536 winter flounder Pseudopleuronectes americanus larvae collected from three locations in eastern Long Island Sound shown to be nursery areas for the species. Substantial genetic differences were seen among the putative source populations and thus appeared to be geographically based. These differences were used to characterize the most likely sources of winter flounder larvae entrained at the Millstone Power Station as well as recruitment to juvenile winter flounder collected in the Niantic River. Samples were classified to the most likely geographical source population both by a conditional maximum likelihood method and by a multi-layer feed-forward neural net trained on the differences in microsatellite allele frequencies. The classification of samples by both methods is compared and discussed in the context of winter flounder management. [source] Strengthening Forensic Science: A Way Station on the Journey to JusticeJOURNAL OF FORENSIC SCIENCES, Issue 1 2010Thomas L. Bohan Ph.D. No abstract is available for this article. [source] Herpes B-virus seroreactivity in a colony of Macaca mulatta: data from the Sabana Seca Field Station, a new Specific Pathogen-Free ProgramJOURNAL OF MEDICAL PRIMATOLOGY, Issue 1 2005Carlos A. Sariol Abstract:, The demand for B-virus-free animals for biomedical research is increasing, while at the same time the availability of such animals is decreasing. The establishment of Specific Pathogen-Free (SPF) breeding macaque colonies is a priority of the National Institutes of Health. Nevertheless, it is well known that seroreactivity to B-virus can be difficult to interpret, particularly as it can vary over time in a single animal. The aim of the present study was to implement a reliable algorithm to examine B-virus reactivity among the rhesus monkey population of the Caribbean Primate Research Center. The sensitivity and specificity of our assay were determined using reports from two different laboratories as references. Whereas 95.4% of animals showed consistent serological status and 4.6% of animals recruited to this SPF program showed serovariability to B-virus over the initial 2 years of examination. Implications for all SPF programs are discussed in this article. [source] 54 Benthic marine algal herbarium of long island sound digital collectionJOURNAL OF PHYCOLOGY, Issue 2003S. Cudiner The University of Connecticut presents the "Benthic Marine Algal Herbarium of Long Island Sound Digital Collection." The collection is available on the web for teaching and identification purposes. Phase One of this project will be finished later by early next year. Currently, the collection has approximately 60% of all Long Island Sound macroalgae species. The taxonomy is part of a collaboration between the University of Connecticut and the Northeast Algal Society (NEAS). Thus far, the specimens have come from Dr. Charles Yarish's herbarium and from the Environmental Laboratory at Millstone Power Station on Long Island Sound. The botanical illustrations are from "Illustrated Key to the Seaweeds of New England" by Martine Villalard-Bohnsack. Database features include the ability to create searches and generate sets based on subjects, division, class, order, family, genus, habitat, species, keyword, and location. Data retrieved includes JPG image, cataloged data, map regions, synonyms, and illustrated microscopic, cross section and surface view for some species. The web site is available for use at: http://www.algae.uconn.edu [source] RELATING PHYTOPLANKTON DYNAMICS AND PRODUCTION TO SEDIMENT RESUSPENSION IN SOUTHERN LAKE MICHIGANJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Millie, D. F.1, Fahnenstiel, G. L.2, Carrick, H. J.3, Lohrenz, S. E.4, & Schofield, O. M. E.5 1USDA-Agricultural Research Service, Sarasota, FL 34236, USA, 2NOAA-Lake Michigan Field Station, Muskegon, MI 49441, USA, 3Institute of Marine Science, University of Southern Mississippi, Stennis Space Center, MS 39529, USA, 4Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14060, USA; 5Isttitute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road New Brunswick NJ 08901 USA, Sediment resuspension is an annually recurrent feature during spring holomixis in southern Lake Michigan. Relationships between resuspension events and phyt-oplankton biomass, compositional dynamics, and pro-duction were evaluated during 1998 and 1999. Increased water-column light attenuation (KPAR) and suspended particulate matter (SPM) concentrations corresponded with resuspension events within nearshore regions. However, neither KPAR nor SPM corresponded with chlorophyll (Chl) a concentrations, indicating no impact of resuspension on instantaneous biomass accumulation. Diatoms and cryptophytes dominated phytoplankton assemblages and together typically comprised greater than 85% of the Chl a. The associations of SPM/KPAR with diatom Chl a, and the inverse relationship between relative diatom and crypto-phyte Chl a corresponded with the dominance of diatoms and cryptophytes in near- and offshore waters, respectively. Moreover, a spatial variation in species composition occurred during resuspension events; small, centric diatoms exhibiting meroplanktonic life histories and large, pennate diatoms considered benthic in origin were associated with sediment resuspension whereas large, net diatoms and cryptophytes typically comprising phytoplankton of the annual spring bloom and of optically-clear, offshore waters were not. The presence of viable diatom photopigments and the abundance of small centric diatoms within the surficial sediments, established this layer as the source of meroplankton. Integral production was dramatically reduced within sediment-impacted waters; however, nearshore assemblages appeared to have greater photosynthetic capacities than offshore assemblages. Although resuspension dramatically influenced near-shore phytoplankton assemblages, it appeared to have little, if any relationship with the compositional development of the annual spring bloom. [source] Identity and Pathogenicity of Fungi Associated with Root and Crown Rot of Soft Red Winter Wheat Grown on the Upper Coastal Plain Land Resource Area of MississippiJOURNAL OF PHYTOPATHOLOGY, Issue 2 2000M. S. Gonzalez Seedling stand, disease severity and fungal incidence were determined from untreated ,Wakefield' soft red winter wheat planted on a Leeper silty clay loam in field tests conducted at the Mississippi Agricultural and Forestry Experiment Station, Plant Science Research Center, Mississippi State University, Starkville, Mississippi during the 1996,97 and 1997,98 growing seasons. Seedling stand was reduced by 40% each year in plots established with untreated seed. Cochliobolus sativus was the most frequently isolated fungus. Fusarium acuminatum, Fusarium equiseti and Fusarium solani were the most prevalent Fusarium spp. Seven other Fusarium spp. and 23 species of other fungal genera were isolated. Pathogenicity tests with three isolates each of C. sativus, Cochliobolus spicifer, F. acuminatum, F. solani, F. equiseti, Fusarium compactum, Embellisia chlamydospora and Microdochium bolleyi were performed in test tube culture and two isolates each of C. sativus, C. spicifer, F. acuminatum, E. chlamydospora and M. bolleyi under greenhouse conditions. In test tubes and in the greenhouse, seedlings infected with isolates of C. sativus developed seedling blight, discoloration and necrosis, primarily in seminal roots and crowns. In the greenhouse, C. sativus induced lesions on the lower leaf sheath and reduced seedling height, seedling emergence, dry and fresh weight of roots and shoots. Isolates of F. acuminatum, F. solani, F. equiseti, F. compactum, E. chlamydospora and M. bolleyi induced slight to moderate orange to light-brown discoloration of crown and seminal roots in test tubes. Cochliobolus spicifer isolates had the most pre-emergence activity, inducing black root discoloration and root pruning of wheat seedlings and reducing seedling emergence, root fresh weight and shoot dry weight. In the greenhouse, F. acuminatum reduced seedling height, seedling emergence and root and shoot dry weights. Microdochium bolleyi and E. chlamydospora reduced fresh and dry weight of roots, plant emergence and shoot dry weight. Fusarium acuminatum and C. spicifer reduced the growth rate of wheat seedlings. All fungi evaluated showed increased disease severity compared to the untreated control. The high frequency of isolation of C. sativus from crown and root tissues can be partially explained by the dry, warm conditions during the early stages of wheat seedling development in the Upper Coastal Plain Land Resource Area of Mississippi. Zusammenfassung Die Auflaufrate von Sämlingen, die Stärke des Krank-heitsbefalls sowie die Häufigkeit von Pilzarten wurden bei nicht behandelten roten Weichwinterweizen der Sorte Wakefield ermittelt, welche in einem Leeper schlammigen Tonboden an der Mississippi Agricultural & Forestry Experiment Station, Plant Science Research Center, Mississippi State University, Starkville, Mississippi in der 1996,97 und 1997,98 Saison gesät worden waren. In beiden Jahren wurde die Auflaufrate von nicht behandeltem Saatgut um 40% reduziert. Cochliobolus sativus wurde am häufigsten isoliert. Fusarium acuminatum, Fusarium equiseti und Fusarium solani waren die überwiegenden Fusarium spp. Außierdem wurden sieben weitere Fusarium spp. sowie 23 weitere Pilzarten isoliert. Pathogenitätstests mit je 3 Isolaten von C. sativus, Cochliobolus spicifer, F. acuminatum, F. solani, F. equiseti, Fusarium compactum, Embellisia chlamydospora und Microdochiumbolleyi wurden in Reagenzröhrchen durchgeführt, sowie mit je 2 Isolaten von C. sativus, C. spicifer, F. acuminatum, E. chlamydospora und M. bolleyi unter Gewächshausbedingungen. Sowohl in den Reagenzröhrchen als auch im Gewächshaus entwickelten Sämlinge, die mit C. sativus inokuliert worden waren, eine Fäule, Verfärbung sowie Nekrosis, hauptsächlich in den sekundären Wurzeln und in den Halmbasen. Unter Gewächshausbedingungen verursachte C. sativus außierdem Läsionen der unteren Blattscheide sowie eine Reduzierung des Sämlingswachstums, des Sämlingsauflaufs, des Trocken-und Frischgewichts der Wurzeln und Sprossen. Im Reagenzröhrchentest induzierten Isolate von F. acuminatum, F. solani, F. equiseti, F. compactum, E. chlamydospora und M. bolleyieine schwache bis mäßiige orange bis hell braune Verfärbung des Halmbasis und der Sekundärwurzeln. Isolate von C. spicifer besaßien die höchste Vorauflaufaktivität und induzierten eine Verschwärzung und Verkürzung der Wurzeln sowie eine Reduzierung des Sämlingsauflaufs, des Wurzelfrischgewichts sowie des Sproitrockengewichts. Unter Gewächshausbedingungen reduzierte F. acuminatum die Sämlingshöhe, die Auflaufrate sowie das Trockengewicht der Wurzeln und Sproien. Microdochium bolleyi und E. chlamydospora reduzierten das Frisch-und Trockengewicht der Wurzeln, die Auflaufrate sowie das Sproßitrockengewicht. Die Wachstumsrate der Sämlinge wurde durch F. acuminatum und C. spicifer reduziert. Alle untersuchten Pilzarten erhöhten die Befallsstärke verglichen mit der unbehandelten Kontrolle. Die hohe Isolierungsrate von C. sativus aus dem Halmbasis-und Wurzelgewebe kann zum Teil dadurch erklärt werden, dass während der Frühentwicklungsphase der Sämlinge trockene und warme Wachstumsbedingungen in diesem Gebiet herrschten. [source] | |||||||||||||||||||||||||||||||||||||