Enclosures

Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Enclosures

  • field enclosure
  • large enclosure
  • outdoor enclosure

  • Terms modified by Enclosures

  • enclosure experiment

  • Selected Abstracts


    ECONOMY OF THE GIFT: RETHINKING THE ROLE OF LAND ENCLOSURE IN POLITICAL ECONOMY*

    MODERN THEOLOGY, Issue 3 2009
    TODD S. MEI
    The theological revivification of the concept of gift and gift exchange in the last two decades has provoked questions on how notions of divine superabundance can be translated into economics. In this article, I relate the thinking of Paul Ricoeur, John Milbank, Philip Goodchild and Albino Barrera to a specific economic reform that entails seeing land enclosure as inimical to the stability and fairness of an economy. I refer to the political economy of Henry George (1839,97) which takes land value taxation to be its centrally defining principle for a just economy. [source]


    Multiple Paternity and Similar Variance in Reproductive Success of Male and Female Wood Mice (Apodemus sylvaticus) Housed in an Enclosure

    ETHOLOGY, Issue 10 2001
    Susan Bartmann
    The mating system and variance in individual reproductive success in wood mice (Apodemus sylvaticus) were analysed genetically and using observational studies within a large cage system in an outdoor enclosure. Four experimental groups contained four males and four females, each individually marked with a transponder (small computer chips injected under the skin) allowing individual detection of animals underground or within nest boxes without disturbance. The probability of paternity was analysed by comparing frequencies of cohabitation of males and females. In addition, DNA microsatellite analysis revealed reproductive success of each individual. Multiple paternity was found in 85% of all litters, which were sired by up to all four males. Males with a greater body mass, possibly indicative of a higher rank, sired more offspring than those with lower body mass. Interestingly, variance in the reproductive success of males and females did not differ. There was no indication that paternity could be assessed by the time males resided with a female shortly before she became pregnant. Our results indicate wood mice probably have a promiscuous mating system. [source]


    The Sheer Opacity of Contemporary Enclosure

    JOURNAL OF ARCHITECTURAL EDUCATION, Issue 2 2003
    CATHRINE VEIKOS
    Skins & Screens, the graduate-level elective studio offered at the University of Pennsylvania, posits the building surface as a dynamic condition, simultaneously real and illusory, opaque and evanescent. Termed sheer opacity, this quality of enclosure provides an investigative focus for the consideration of surface as a dynamic perceptual field, a site for the mediation of physical and perceptual phenomena. Close analysis of selected work of the West Coast art movement Light and Space and that of contemporary installation artists inspired projects that used sheer opacity to examine the possibility of transforming space through the design of the building surface. Projects were developed through a series of "layers" in which students made installations, material constructs, digital simulations, and large-scale detail studies of their proposals. [source]


    Geophysical surveys at King Lobengula's Palace KoBulawayo, Zimbabwe

    ARCHAEOLOGICAL PROSPECTION, Issue 1 2005
    C. Gaffney
    Abstract This report covers the application of magnetic survey, primarily using a magnetic susceptibility field instrument, at the historically attested site of KoBulawayo, Zimbabwe. The approximate position of the site was known before the geophysical survey took place; it was believed to comprise a Royal Enclosure, a surrounding open space possibly used as a military parade ground and the Commoner/Peripheral Settlement of Lobengula, King of the Ndebele. Occupation at the site was short lived and after only 11 years the capital of the Ndebele state was destroyed by fire in 1881. A pilot survey was undertaken in 1994 to assess the suitability of survey techniques. Consequently, a second, more extensive survey was carried out in late 1996 and early 1997 with the intention of delimiting the Royal Enclosure. Further periods of data collection took place later in 1997 and in 1998. This report describes the methods used and the interpretation of the geophysical results in the context of the understanding and management of this important historical site. Additionally, some of the results of the geophysical work have been tested by excavation and a discussion of the correlation between these data sets is also reported in this article. Copyright © 2004 John Wiley & Sons, Ltd. [source]


    Effects of predation and habitat structure on the population dynamics of house mice in large outdoor enclosures

    OIKOS, Issue 3 2005
    Anthony D. Arthur
    This paper examines the effect of different levels of protection from predation on feral house mice. Mice were contained in eight 50×50 m outdoor enclosures. Enclosures allowed access to a suite of freeliving vertebrate predators from the surrounding area, including feral foxes, feral cats and Australian raptors. A 10,15% cover of small, felled cypress pine trees was added in strips to low grassland to increase habitat complexity. Mice were not protected from predation when compared with low grassland pens, possibly because predators were able to focus their hunting activity in the strips. However, when felled trees were covered with wire netting, hence providing higher quality refuge, mouse populations achieved higher densities than in low grassland pens. A predator exclusion treatment was used to confirm the refuge effect was due to a reduction in the impact of predation. Survival rates under the different treatments were generally consistent with population level responses, with mice having lower survival in low grassland pens than in high refuge pens. This is the first study with mammals that confirms the importance of refuges from predators for prey populations. [source]


    Natural Convection in Heat Generating Oval Porous Enclosures: A Non-Darcian Model

    THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2003
    Subrat Das
    Abstract This paper presents a series of numerical simulations dealing with the problem of natural convection flows and associated heat transfer in an enclosure filled with a fluid-saturated porous medium. The analysis is based on the finite element technique and incorporates the Brinkman-extended Darcy model for an oval enclosure. The numerical results obtained for a modified Rayleigh number, Ra, Darcy number, Da, offset, E, and eccentricity, e, are presented and discussed. The numerical predictions for a square enclosure compared well with published data. It is found that any increase in Da or Ra results in a higher fluid velocity that is responsible for shifting the core of the flow. Moreover, at higher ovality (E = 0.5), asymmetric flow is observed even at the lower range of Rayleigh number (Ra , 20), which may be attributed to the effect of curved isothermal wall. On présente dans cet article une série de simulations numériques des écoulements avec convection naturelle et du transfert de chaleur associé, dans une enceinte remplie d'un milieu poreux saturé en fluide. L'analyse repose sur la technique des éléments finis et fait appel à un modèle généralisé de Darcy-Brinkman pour une enceinte de forme ovale. Les résultats numériques obtenus pour le nombre de Rayleigh modifié, Ra, le nombre de Darcy, Da, le décentrement, E, et l'eccentricité, e, sont présentés et analysés. Les prédictions numériques pour une enceinte carrée se comparent bien aux données publiées. On trouve que toute augmentation de Da ou Ra entraîne une plus grande vitesse de fluide qui est responsable du déplacement du c,ur de l'écoulement. En outre, à une plus grande ovalité (E = 0,5), un écoulement asymétrique est observé même dans la gamme inférieure de nombre de Rayleigh (Ra" 20), ce qui peut être l'effet de la paroi isotherme courbée. [source]


    GOVERNMENTALITY, LANGUAGE IDEOLOGY, AND THE PRODUCTION OF NEEDS IN MALAGASY CONSERVATION AND DEVELOPMENT

    CULTURAL ANTHROPOLOGY, Issue 2 2007
    PAUL W. HANSON
    Integrated conservation and development program planning pivots on a critical exchange. In establishing protected areas, part of the subsistence base of resident people is enclosed. Residents are then offered assistance in meeting needs emerging from the enclosure. The elicitation and interpretation of need in such programs forms a technology of governance. This article analyzes differing linguistic ideologies underpinning needs production in Madagascar's Ranomafana National Park Project, arguing that the technology of needs production is part of a green neoliberal rationality through which the Malagasy state and its citizens are being transformed, and from which an increasingly sophisticated countergovernmentality grows. [source]


    Therapeutic effects of complex rearing or bFGF after perinatal frontal lesions

    DEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2008
    Wendy Comeau
    Abstract We investigated the effects of an enriched environment and/or basic fibroblast growth factor (bFGF) on recovery from neonatal frontal injury in rats. Rats received medial frontal lesions, or sham surgery, on postnatal day (P) 2/3. In the first set of experiments (Experiments 1 and 2), rats were housed in enriched environments that consisted of a large enclosure with multiple objects (or standard housing) for 90 days beginning at weaning (P22) or in adulthood (P110). In Experiment 3, the rats either received 7 days of subcutaneous bFGF beginning on the day after surgery or bFGF plus enriched housing beginning at weaning. After the 90-day housing period, the animals were tested on a spatial navigation task and a skilled reaching task. Early lesions of the medial frontal cortex caused severe impairments in spatial learning but this deficit was markedly reduced with enriched housing, bFGF, or a combination of both, with the latter being most effective. The housing effects varied with age, however: the earlier the experience began, the better the outcome. Enriched housing increased dendritic length in cortical pyramidal neurons, an effect that was greater in the lesion than the control animals, and enriched housing reversed the lesion-induced decrease in spine density. Enriched environment increased the thickness of the cortical mantle in both lesion and controls whereas bFGF had no effect. Experience thus can affect functional and anatomical outcome after early brain injury but the effects vary with age at experience and may be facilitated by treatment with bFGF. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 134,146, 2008. [source]


    Early recognition of newborn goat kids by their mother: II.

    DEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2003
    Auditory recognition, evidence of an individual acoustic signature in the neonate
    Abstract The vocal recognition of newborn kids by their mother at 2 days postpartum and the possible existence of interindividual differences in the voice structure of newborn kids were investigated in two separate studies. The ability of goats to discriminate between the bleats of their own versus an alien kid was tested at 2 days postpartum in mothers being prevented access to visual and olfactory cues from the young. Goats spent significantly more time on the side of the enclosure from which their own kid was bleating, looked in its direction for longer, and responded more frequently to the bleats of their own than to those of the alien kid (p,<,0.05). In the second study, the sonograms of 13 kids, studied from Days 1 to 5, showed significant interindividual differences for the five variables taken into account and on each of the 5 days (duration of bleat, fundamental frequency, peak frequency, and numbers of segments and of harmonics). The potential for individual coding ranged between 1.1 and 4.1, indicating that for some variables variations between individuals were greater than intraindividual variations. Furthermore, when considering the five parameters together, the discriminating scores showed an average of 95% in the 78 combinations of any 2 kids for any given day. Finally, some significant intraindividual differences also were found between days, suggesting ontogenic changes in the characteristics of the kid's voice in early life. Therefore, mother goats are likely to recognize the vocalizations of their 48-hr-old kids, as they show sufficient interindividual variability to allow the existence of individual vocal signatures, even though some of the characteristics of the bleats change rapidly over time. © 2003 Wiley Periodicals, Inc. Dev Psychobiol 43: 311,320, 2003. [source]


    Satellite sleuthing: does remotely sensed land-cover change signal ecological degradation in a protected area?

    DIVERSITY AND DISTRIBUTIONS, Issue 2 2009
    T. A. Waite
    ABSTRACT Aim, We evaluate whether remotely sensed land-cover change within a newly protected area signalled human-driven ecological degradation. Vegetation density changed in a quarter of pixels during the first 13 years (1986,1999) following the sanctuary's formal enclosure, with many patches showing a decrease in density. We use on-the-ground data collected in 2006 in 132 random plots to explore whether these changes in vegetation density reliably signalled latent shifts in local diversity of woody plants and whether they could be attributed to illicit activities including fuel wood collection and livestock grazing. Location, Kumbhalgarh Wildlife Sanctuary, Rajasthan, India. Results, Species richness, species sharing, species assemblages, and incidence of invasive and useful species were statistically similar among plots in which vegetation density had decreased, increased or remained similar. Likewise, intensity of disturbance associated with human activities was similar across these plot types. Main conclusions, Our data provide no clear evidence that local changes in vegetation density signalled latent shifts in local diversity of woody plants. They also fail to reveal any clear association between local changes in vegetation density and human-related activities. Finding no evidence that land-cover change led to biotic erosion, we reflect on the utility of resource-use bans in protected areas, particularly those embedded within historically coupled human-nature systems. [source]


    Progress and poverty in early modern Europe

    ECONOMIC HISTORY REVIEW, Issue 3 2003
    Robert C. Allen
    An econometric model of economic development is estimated with data from leading European countries between 1300 and 1800. The model explores the impact of population, enclosure, empire, representative government, technology, and literacy on urbanization, agricultural productivity, proto-industry, and the real wage. Simulations show that the main factors leading to economic success in north-western Europe were the growth of American and Asian commerce and, especially, the innovations underlying the export of the new draperies in the sixteenth and seventeenth centuries. The enclosure of the open fields, representative government, and the spread of literacy did not play major roles. [source]


    Multiple Paternity and Similar Variance in Reproductive Success of Male and Female Wood Mice (Apodemus sylvaticus) Housed in an Enclosure

    ETHOLOGY, Issue 10 2001
    Susan Bartmann
    The mating system and variance in individual reproductive success in wood mice (Apodemus sylvaticus) were analysed genetically and using observational studies within a large cage system in an outdoor enclosure. Four experimental groups contained four males and four females, each individually marked with a transponder (small computer chips injected under the skin) allowing individual detection of animals underground or within nest boxes without disturbance. The probability of paternity was analysed by comparing frequencies of cohabitation of males and females. In addition, DNA microsatellite analysis revealed reproductive success of each individual. Multiple paternity was found in 85% of all litters, which were sired by up to all four males. Males with a greater body mass, possibly indicative of a higher rank, sired more offspring than those with lower body mass. Interestingly, variance in the reproductive success of males and females did not differ. There was no indication that paternity could be assessed by the time males resided with a female shortly before she became pregnant. Our results indicate wood mice probably have a promiscuous mating system. [source]


    Rat anterodorsal thalamic head direction neurons depend upon dynamic visual signals to select anchoring landmark cues

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2004
    Michaël B. Zugaro
    Abstract Head direction cells, which are functionally coupled to ,place' cells of the hippocampus, a structure critically involved in spatial cognition, are likely neural substrates for the sense of direction. Here we studied the mechanism by which head direction cells are principally anchored to background visual cues [M.B. Zugaro et al. (2001) J. Neurosci., 21, RC154,1,5]. Anterodorsal thalamic head direction cells were recorded while the rat foraged on a small elevated platform in a 3-m diameter cylindrical enclosure. A large card was placed in the background, near the curtain, and a smaller card was placed in the foreground, near the platform. The cards were identically marked, proportionally dimensioned, subtended the same visual angles from the central vantage point and separated by 90°. The rat was then disoriented in darkness, the cards were rotated by 90° in opposite directions about the center and the rat was returned. Preferred directions followed either the background card, foreground card or midpoint between the two cards. In continuous lighting, preferred directions shifted to follow the background cue in most cases (30 of the 53 experiments, Batschelet V -test, P < 0.01). Stroboscopic illumination, which perturbs dynamic visual signals (e.g. motion parallax), blocked this selectivity. Head direction cells remained equally anchored to the background card, foreground card or configuration of the two cards (Watson test, P > 0.1). This shows that dynamic visual signals are critical in distinguishing typically more stable background cues which govern spatial neuronal responses and orientation behaviors. [source]


    CAN INTRASPECIFIC COMPETITION DRIVE DISRUPTIVE SELECTION?

    EVOLUTION, Issue 3 2004
    AN EXPERIMENTAL TEST IN NATURAL POPULATIONS OF STICKLEBACKS
    Abstract Theory suggests that frequency-dependent resource competition will disproportionately impact the most common phenotypes in a population. The resulting disruptive selection forms the driving force behind evolutionary models of niche diversification, character release, ecological sexual dimorphism, resource polymorphism, and sympatric speciation. However, there is little empirical support for the idea that intraspecific competition generates disruptive selection. This paper presents a test of this theory, using natural populations of the three-spine stickleback, Gasterosteus aculeatus. Sticklebacks exhibit substantial individual specialization associated with phenotypic variation and so are likely to experience frequency-dependent competition and hence disruptive selection. Using body size and relative gonad mass as indirect measures of potential fecundity and hence fitness, I show that an important aspect of trophic morphology, gill raker length, is subject to disruptive selection in one of two natural lake populations. To test whether this apparent disruptive selection could have been caused by competition, I manipulated population densities in pairs of large enclosures in each of five lakes. In each lake I removed fish from one enclosure and added them to the other to create paired low- and high-population-density treatments with natural phenotype distributions. Again using indirect measures of fitness, disruptive selection was consistently stronger in high-density than low-density enclosures. These results support long-standing theoretical arguments that intraspecific competition drives disruptive selection and thus may be an important causal agent in the evolution of ecological variation. [source]


    Full-scale study on combustion characteristics of an upholstered chair under different boundary conditions,Part 1: Ignition at the seat center

    FIRE AND MATERIALS, Issue 6 2009
    Q. Y. Xie
    Abstract The objective of this work is to investigate the effects of boundary conditions on the combustion characteristic of combustible items in a room. A series of full-scale experiments were carried out in the ISO 9705 fire test room with an upholstered chair at four typical locations, i.e. at the middle of side wall, at the center of the room with the seat toward the door, at the center of the room with the seat toward inside of the room, at the room corner, respectively. Ignition was achieved through a BS No.7 wooden crib at the geometric center of the seat surface for each test. Besides the heat release rate (HRR), four thermocouple trees were placed around the chair to monitor detailed temperature distributions during the combustion process of an upholstered chair. The results indicated that the boundary conditions had some effects on the combustion behavior of a chair in a room. It was shown that there were clearly two main peak HRRs for the cases of a chair being clung to the side wall or at the corner. However, there was only one main peak HRR when the chair was placed at the center of the room, either outwards or inwards. In addition, the results of the two cases of chairs being at the center indicate that the maximum HRR (about 829,kW) for the chair seat toward the door was relatively larger than the maximum HRR (about 641,kW) for the chair seat toward inside of the room. It was suggested that the special complex structure of a chair was also a considerable factor for the effect of boundary conditions on the combustion behavior of a chair in an enclosure. Furthermore, the measured temperature distributions around the chair also illustrated the effects of boundary condition on the combustion behavior of a chair in a room. It was suggested that although HRR was one of the most important fire parameters, HRR mainly represented the comprehensive fire behavior of a combustible item. In order to develop more suitable room fire dynamic models, more detailed information such as the surrounding temperature distributions measured by the thermocouple trees are useful. Copyright © 2009 John Wiley & Sons, Ltd. [source]


    Experimental study on water spray suppression on burning upholstered chair in an enclosure with different application times

    FIRE AND MATERIALS, Issue 5 2009
    Q. Y. Xie
    Abstract The objective of this work is to investigate the effects of the application time of water spray on the burning upholstered chair in an enclosure. A series of experiments are conducted with the same water flow rate in an ISO 9705 fire test room in which a water spray system is installed. Several identical upholstered chairs are used in the experiments with the application times 20, 25, 30, 40 and 45,s after the ignition of upholstered chair, respectively. The results show that there is nearly an exponential relationship between the peak heat release rates and the relative application times of water spray. It is also shown that there is a polynomial relationship between the relative time for the peak heat release rate and the relative application time of water spray. However, there is an exponential relationship between the whole relative extinguishing time and the relative application time of water spray. A sudden increase is detected before the decreasing of CO generation rates after the water spray is applied on the burning upholstered chair. The average temperatures of the upper hot smoke layer under the ceiling will generally be lower with the earlier application of water spray. Copyright © 2009 John Wiley & Sons, Ltd. [source]


    Predicting HCl concentrations in fire enclosures using an HCl decay model coupled to a CFD-based fire field model

    FIRE AND MATERIALS, Issue 7 2007
    Z. Wang
    Abstract The amount of atmospheric hydrogen chloride (HCl) within fire enclosures produced from the combustion of chloride-based materials tends to decay as the fire effluent is transported through the enclosure due to mixing with fresh air and absorption by solids. This paper describes an HCl decay model, typically used in zone models, which has been modified and applied to a computational fluid dynamics (CFD)-based fire field model. While the modified model still makes use of some empirical formulations to represent the deposition mechanisms, these have been reduced from the original three to two through the use of the CFD framework. Furthermore, the effect of HCl flow to the wall surfaces on the time to reach equilibrium between HCl in the boundary layer and on wall surfaces is addressed by the modified model. Simulation results using the modified HCl decay model are compared with data from three experiments. The model is found to be able to reproduce the experimental trends and the predicted HCl levels are in good agreement with measured values. Copyright © 2006 John Wiley & Sons, Ltd. [source]


    Characterization of the fire environments in central offices of the telecommunications industry

    FIRE AND MATERIALS, Issue 3 2003
    Archibald Tewarson
    Abstract Eight free burning and two sprinklered fire tests were performed with electrical cable trays and live digital switch racks in a large enclosure to simulate telecommunications central office (TCO) fires started by electrical overheating. Very-slow-growing (non-flaming), slower-growing (partially flaming) and low-intensity-faster-growing (flaming) fires releasing gray-white, gray, and black smoke, respectively, were observed in the tests. Under quiescent conditions present in the unvented enclosure fire tests for cables, very-slow-growing fires were detected in about 1452 s, whereas the slower-growing fires were detected in about 222 s by commercial fire detectors. Under ventilation conditions typical of TCOs, detection times were very similar for the five types of commercial TCOs fire detectors used in the tests. The average detection times for slower-growing fires (cable fires) and low-intensity-faster-growing fires (digital switch rack fires) were 242±17% and 249±11%s respectively. The TCO procedures to reduce smoke damage from fires (on fire detection, inlet ventilation flow is turned off and exhaust flow is turned on) were found to be beneficial. The extent of smoke damage decreased significantly with an increase in the exhaust flow rate. The chloride ion mass deposition suggested that equipment recovery would be possible in the smoke environment if the cable vapor concentration could be reduced below about 3 g/m3. The metal corrosion rate was found proportional to the 0.6th power of the smoke concentration, similar to that found for the corrosion of metal surfaces exposed to aqueous solutions of HCl and HNO3 and for acid rain with no protective layer at the surface. Sprinkler water was found to wash down the smoke deposits on the surfaces with little indication of corrosion enhancement. Copyright © 2003 John Wiley & Sons, Ltd. [source]


    Characterization of the combustion products in large-scale fire tests: comparison of three experimental configurations

    FIRE AND MATERIALS, Issue 2 2001
    Per Blomqvist
    The storage of large amounts of polymers and other bulk chemicals is a potential hazard in the case of fire. There is at present a lack of knowledge about the implications of such fires. In particular the role of the ventilation conditions on fire chemistry has warranted investigation. A set of indoor, large-scale combustion experiments, conducted on five different materials is described in this article. The main test series was conducted using the ISO 9705 room, where both well-ventilated and under-ventilated conditions were attained by restricting the opening of the room. The degree of ventilation was determined using a phi meter. Furthermore, in addition to measuring the traditional fire-related parameters, extensive chemical characterization of the combustion products was made. Two additional series of experiments were also performed. In one series of tests the size of the enclosure was increased and the fuel was placed in a storage configuration to simulate a real storage situation. In the other test series, three of the materials were tested as large-scale open pool fires. The results from the three configurations are compared regarding yields of combustion products as a function of the degree of ventilation. For a number of toxic combustion products a clear dependence of the production on the equivalence ratio was found. Further, placing the fuel in a storage configuration did not significantly change the outcome of the combustion. Thus, the ISO 9705 room is of a size and scale that can be taken as a model for representing real-scale fires. Additionally it has been demonstrated that an advantage of the ISO 9705 room is the ability to alter the ventilation conditions. Copyright © 2001 John Wiley & Sons, Ltd. [source]


    Iron-mediated suppression of bloom-forming cyanobacteria by oxine in a eutrophic lake

    FRESHWATER BIOLOGY, Issue 5 2010
    LEWIS A. MOLOT
    Summary 1. Published studies show that cyanobacteria have higher Fe requirements than eukaryotic algae. To test whether Fe availability can affect formation of a cyanobacterial bloom, a strong Fe chelator, oxine (8-hydroxyquinoline, C9H7NO), was added to enclosures in eutrophic Lake 227 in the Experimental Lakes Area (ELA) (northwestern Ontario). 2. Aphanizomenon schindlerii growth was suppressed, and growth of eukaryotic chlorophytes significantly promoted in enclosures to which oxine had been added. Significant eukaryotic growth did not occur in enclosures treated with ammonium, suggesting that N supplied by degradation of oxine was not responsible for eukaryotic success in the oxine enclosures. 3. In situ Fe2+ measurements were unreliable because of interference from high concentrations of dissolved organic compounds. However, oxine rapidly promoted oxidation of Fe2+ to Fe3+ in deionised water, suggesting that rapid removal of Fe2+ also occurred in the oxine-treated enclosures. 4. In batch cultures, 10 ,m Fe and 10 ,m oxine (a 1 : 1 ratio) completely inhibited the growth of the cyanobacteria Synechococcus sp. and Anabaena flos-aquae and the chlorophytes Pseudokirchneriella subcapitata and Scenedesmus quadricauda. Increasing Fe 10-fold to 100 ,m Fe completely and partially reversed oxine inhibition in the two chlorophytes but could not overcome inhibition of the cyanobacteria, indicating that inhibition was Fe-mediated at least in the eukaryotes. Since oxine binds Fe3+ in a 1 : 3 ratio (Fe : oxine), inhibition at a 1 : 1 ratio indicates that not all of the Fe is bound, and a mechanism involving Fe other than chelation was at least partly responsible for inhibition. 5. Collectively, the enclosure and laboratory results suggest that the outcome of competition between cyanobacteria and eukaryotic algae in the oxine-treated enclosures in Lake 227 was likely a result of decreased availability of Fe, especially Fe2+. 6. The results suggest that remediation methods that dramatically restrict the supply rate of Fe2+ could reduce the relative abundance of cyanobacteria in eutrophic systems. [source]


    Stream temperature and the potential growth and survival of juvenile Oncorhynchus mykiss in a southern California creek

    FRESHWATER BIOLOGY, Issue 7 2007
    DAVID A. BOUGHTON
    Summary 1.,We asked whether an increase in food supply in the field would increase the ability of fish populations to withstand climate warming, as predicted by certain bioenergetic models and aquarium experiments. 2.,We subsidised the in situ food supply of wild juvenile steelhead (Oncorhynchus mykiss) in a small stream near the species' southern limit. High-quality food (10% of fish biomass per day) was added to the drift in eight in-stream enclosures along a naturally-occurring thermal gradient. 3.,The temperatures during the experiment were well below the upper thermal limit for the species (means of enclosures ranged from 15.1 to 16.5 °C). Food supplements had no discernible effect on survival, but raised mean (± SD) specific growth rate substantially, from 0.038 ± 0.135 in controls to 2.28 ± 0.51 in feeding treatments. Food supplements doubled the variation in growth among fish. 4.,The mean and variance of water temperature were correlated across the enclosures, and were therefore transformed into principal component scores T1 (which expressed the stream-wide correlation pattern) and T2 (which expressed local departures from the pattern). Even though T1 accounted for 96% of the variation in temperature mean and variance, it was not a significant predictor of fish growth. T2 was a significant predictor of growth. The predicted time to double body mass in an enclosure with a large T2 score (cool-variable) was half that in an enclosure with a low T2 score (warm-stable). 5.,Contrary to expectation, temperature effects were neutral, at least with respect to the main axis of variation among enclosures (cool-stable versus warm-variable). Along the orthogonal axis (cool-variable versus warm-stable), the effect was opposite from expectations, probably because of temperature variation. Subtle patterns of temperature heterogeneity in streams can be important to potential growth of O. mykiss. [source]


    Evaluation of gastric toxicity of indomethacin acid, salt form and complexed forms with hydroxypropyl-,-cyclodextrin on Wistar rats: histopathologic analysis

    FUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 6 2009
    A.C. Ribeiro-Rama
    Abstract Indomethacin (IM) is a non-steroidal anti-inflammatory drug which inhibits prostaglandin biosynthesis. It is practically insoluble in water and has the capacity to induce gastric injury. Hydroxypropyl-,-cyclodextrin (HP-,-CD) is an alkylated derivative of ,-CD with the capacity to form inclusion complexes with suitable molecules. IM is considered to form partial inclusion complexes with HP-,-CD by enclosure of the p -chlorobenzoic part of the molecule in the cyclodextrin channel, reducing the adverse effects. The aim of this paper is to evaluate the gastric damage induced by the IM inclusion complex prepared by freeze-drying and spray-drying. A total of 135 Wistar rats weighing 224.4 ± 62.5 g were put into 10 groups. They were allowed free access to water but were maintained fasted for 18 h before the first administration until the end of the experiment. IM acid-form, IM trihydrated-sodium-salt and IM-HP-,-CD spray and freeze-dried, at normal and toxic doses, were administered through gastric cannula once/day for 3 days. Seventy-two hours after the first administration, the animals were sacrificed and the stomachs collected and prepared for morphological study by using the haematoxylin-eosin technique. Lesion indexes (rated 0/4) were developed and the type of injury was scored according to the severity of damage and the incidence of microscopic evidence of harm. Microscopic assessment demonstrated levels of injury with index one on 10,25%. The type of complexation method had different incidence but the same degree. The results show that IM inclusion complexation protects against gastric injury, reducing the incidence and the maximum degree of severity from 4 to 1, with a better performance of the spray-dried complex. [source]


    Quantifying prehistoric soil erosion,A review of soil loss methods and their application to a Celtic square enclosure (Viereckschanze) in Southern Germany

    GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 8 2007
    Matthias Leopold
    This paper discusses the strengths and weaknesses of three different methods for quantifying prehistoric soil erosion. Method A estimates erosion by determining the amount of colluvium stored downhill. Method B involves reconstructing a former erosion surface using truncated soil horizons. Method C compares the elevation of a paleosol beneath an earthwork with the modern surface in the surrounding area. Each method was applied to a Celtic earthwork (Viereckschanze) at Poign (near Regensburg) in Southern Germany in order to cross-check the different results. For an erosion area of 3.6 ha and during 300 years of agricultural usage, Method A calculates a minimum erosion rate of 20.8 t/ha/a. Method B computes 10 t/ha/a of soil loss. Method C yields the highest rate of erosion with 24.2 t/ha/a. We have confidence in Method C, which implies an underassesment of soil loss in using methods A or B. © 2007 Wiley Periodicals, Inc. [source]


    Temperature dependence of Fe(III) and sulfate reduction rates and its effect on growth and composition of bacterial enrichments from an acidic pit lake neutralization experiment

    GEOBIOLOGY, Issue 4 2005
    J. MEIER
    ABSTRACT Microbial Fe(III) and sulfate reduction are important electron transport processes in acidic pit lakes and stimulation by the addition of organic substrates is a strategy to remove acidity, iron and sulfate. This principle was applied in a pilot-scale enclosure in pit lake 111 (Brandenburg, Germany). Because seasonal and spatial variation of temperature may affect the performance of in situ experiments considerably, the influence of temperature on Fe(III) and sulfate reduction was investigated in surface sediments from the enclosure in the range of 4,28 °C. Potential Fe(III) reduction and sulfate reduction rates increased exponentially with temperature, and the effect was quantified in terms of the apparent activation energy Ea measuring 42,46 kJ mol,1 and 52 kJ mol,1, respectively. Relatively high respiration rates at 4 °C and relatively low Q10 values (,2) indicated that microbial communities were well adapted to low temperatures. In order to evaluate the effect of temperature on growth and enrichment of iron and sulfate-reducing bacterial populations, MPN (Most Probable Number) dilution series were performed in media selecting for the different bacterial groups. While the temperature response of specific growth rates of acidophilic iron reducers showed mesophilic characteristics, the relatively high specific growth rates of sulfate reducers at the lowest incubation temperature indicated the presence of moderate psychrophilic bacteria. In contrast, the low cell numbers and low specific growth rates of neutrophilic iron reducers obtained in dilution cultures suggest that these populations play a less significant role in Fe and S cycling in these sediments. SSCP (Single-Strand Conformation Polymorphism) or DGGE (Denaturing Gradient Gel Electrophoresis) fingerprinting based on 16S rRNA genes of Bacteria indicated different bacterial populations in the MPN dilution series exhibiting different temperature ranges for growth. [source]


    Development of a finite element radiation model applied to two-dimensional participating media

    HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 6 2005
    Hong Qi
    Abstract A finite element method (FEM) for radiative heat transfer has been developed and it is applied to 2D problems with unstructured meshes. The present work provides a solution for temperature distribution in a rectangular enclosure with black or gray walls containing an absorbing, emitting, isotropically scattering medium. Compared with the results available from Monte Carlo simulation and finite volume method (FVM), the present FEM can predict the radiative heat transfer accurately. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(6): 386,395, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20076 [source]


    Body protein does not vary despite seasonal changes in fat in the White Stork Ciconia ciconia

    IBIS, Issue 1 2002
    Delphine Michard-Picamelot
    To understand how a large soaring bird, the White Stork Ciconia ciconia, copes with energy constraints, we compared changes in body mass in 14 captive adult storks with the body composition of 12 free-ranging adult storks found dead from accidents. The captive storks, already in an enclosure for several years, were fed ad libitum. They were weighed daily for 1.5,3.5 years using an automatic device. The bodies of the accidentally killed storks were analysed to determine total water, lipid, protein and ash contents, and to assess the biochemical composition of certain organs. Females were on average 20% lighter and 24% smaller than males, but the body mass of the sexes varied in parallel throughout the year. Body mass peaked in December and January (25,30% above minimal body mass), due essentially to large fat stores in subcutaneous and abdominal adipose tissues. Body mass and body lipid rapidly decreased from February to June, whether the storks reared chicks successfully or not, and remained minimal for a few days into July. In contrast to birds using flapping flight, no variation in body protein or pectoral muscle protein was observed while breeding, even though the moult occurred then, nor in August, before the time when wild storks migrate. An endogenous regulation of body fuels is discussed. [source]


    Fast single domain,subdomain BEM algorithm for 3D incompressible fluid flow and heat transfer

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 12 2009
    Jure Ravnik
    Abstract In this paper acceleration and computer memory reduction of an algorithm for the simulation of laminar viscous flows and heat transfer is presented. The algorithm solves the velocity,vorticity formulation of the incompressible Navier,Stokes equations in 3D. It is based on a combination of a subdomain boundary element method (BEM) and single domain BEM. The CPU time and storage requirements of the single domain BEM are reduced by implementing a fast multipole expansion method. The Laplace fundamental solution, which is used as a special weighting function in BEM, is expanded in terms of spherical harmonics. The computational domain and its boundary are recursively cut up forming a tree of clusters of boundary elements and domain cells. Data sparse representation is used in parts of the matrix, which correspond to boundary-domain clusters pairs that are admissible for expansion. Significant reduction of the complexity is achieved. The paper presents results of testing of the multipole expansion algorithm by exploring its effect on the accuracy of the solution and its influence on the non-linear convergence properties of the solver. Two 3D benchmark numerical examples are used: the lid-driven cavity and the onset of natural convection in a differentially heated enclosure. Copyright © 2008 John Wiley & Sons, Ltd. [source]


    Effect of ventilation strategies on air contaminant concentrations and energy consumption in buildings

    INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 12 2001
    Ismail M. Budaiwi
    Abstract Considering the diversity of indoor contaminant characteristics and generation patterns, finding an appropriate ventilation strategy that can secure acceptable indoor air quality with minimum energy consumption is a challenging task for HVAC system designers and operators. This study theoretically models and investigates the impact of various ventilation strategies on contaminant concentration behaviour and corresponding ventilation cooling energy requirements for a single-zone enclosure. Two types of contaminants are considered; carbon dioxide as an occupancy dependent and formaldehyde, which is independent of occupancy. An airflow model is used to predict space pressure and air leakage rates across the enclosure envelope, and an air quality model is used to predict time-varying contaminant concentrations. In addition, a building energy simulation model is utilized to predict the corresponding ventilation cooling energy requirements under hot climatic conditions. Results from this study show that acceptable contaminant concentrations during occupied periods can be achieved by different ventilation strategies but at substantially different ventilation energy requirements. More than 50 per cent reduction in ventilation energy requirements can be obtained while maintaining acceptable IAQ if proper ventilation strategy is employed. Copyright © 2001 John Wiley & Sons, Ltd. [source]


    Effects of construction noise on behaviour of and exhibit use by Snow leopards Uncia uncia at Basel zoo

    INTERNATIONAL ZOO YEARBOOK, Issue 1 2008
    C. E. SULSER
    Noise caused by human activities can cause stress in animals. We examined whether noise from construction sites affects the behaviour of and exhibit use by three Snow leopards Uncia uncia at Basel zoo. The behaviour and location of the animals were recorded at 1 minute intervals, using the instantaneous scan sampling method over a period of 216 hours (104 hours on noisy days and 112 hours on quiet days). The animals differed individually in their responses to the construction noise. On noisy days, the Snow leopards generally spent less time in locomotion and more time resting, but even on quiet days, resting was the predominant behaviour performed. Under noisy conditions, they increased social resting and decreased resting alone. Walking and social walking were also reduced on noisy days. Furthermore, the Snow leopards spent considerably more time in the remote off-exhibit enclosure under noisy conditions. Independent of background noise, they stayed more than half of the time in the caves and the forecourts of the outdoor enclosure. On quiet days, the Snow leopards used more sectors of their exhibit than on noisy days. The results indicate that the Snow leopards responded to construction noise by increasing the amount of time spent resting and by withdrawing to the remote parts of their exhibit. [source]


    Chimpanzee Forest exhibit at Chester Zoo

    INTERNATIONAL ZOO YEARBOOK, Issue 1 2006
    S. WEHNELT
    In 2000 an exhibit was altered substantially for Chimpanzees Pan troglodytes at Chester Zoo. A flat grass-covered island was initially planted with over 300 plants of 31 species and a complex climbing structure, made from poles, hammocks, tyres and cargo nets, was erected in the centre of the enclosure. In this article the new Chimpanzee Forest exhibit is described and details of the plantings are given. The ways in which the structure and vegetation have improved the environment and how the Chimpanzees use the redesigned space are also reported. [source]