AUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS, Issue 1 2005
Edward Cripps
Summary This paper develops a space-time statistical model for local forecasting of surface-level wind fields in a coastal region with complex topography. The statistical model makes use of output from deterministic numerical weather prediction models which are able to produce forecasts of surface wind fields on a spatial grid. When predicting surface winds at observing stations, errors can arise due to sub-grid scale processes not adequately captured by the numerical weather prediction model, and the statistical model attempts to correct for these influences. In particular, it uses information from observing stations within the study region as well as topographic information to account for local bias. Bayesian methods for inference are used in the model, with computations carried out using Markov chain Monte Carlo algorithms. Empirical performance of the model is described, illustrating that a structured Bayesian approach to complicated space-time models of the type considered in this paper can be readily implemented and can lead to improvements in forecasting over traditional methods. [source]

Climate Variability in Regions of Amphibian Declines

CONSERVATION BIOLOGY, Issue 4 2001
Michael A. Alexander
The reanalysis system merges observations from airplanes, land stations, satellites, ships, and weather balloons with output from a weather-forecast model to create global fields of atmospheric variables. Station data consisted of temperature and precipitation measured with thermometers and rain gauges at fixed locations. Temperatures were near normal in Colorado when the amphibian declines occurred in the 1970s, whereas in Central America temperatures were warmer than normal, especially during the dry season. The station data from Puerto Rico and Australia indicated that temperatures were above normal during the period of amphibian declines, but reanalysis did not show such a clear temperature signal. Although declines occurred while the temperature and precipitation anomalies in some of the regions were large and of extended duration, the anomalies were not beyond the range of normal variability. Thus, unusual climate, as measured by regional estimates of temperature and precipitation, is unlikely to be the direct cause of amphibian declines, but it may have indirectly contributed to them. Previous researchers have noted that the declines appear to have propagated from northwest to southeast from Costa Rica to Panama and from southeast to northwest in Queensland, Australia. Wind has the potential to transport pathogens that cause amphibian mortality. The mean direction of the near-surface winds tended to parallel the path of amphibian declines from July,October in Central America and from May,July in Australia. The wind direction was highly variable, however, and the propagation rate of amphibian declines was much slower than the mean wind speed. In addition, the most likely pathogen is a chytrid fungus that does not produce desiccation-resistant spores. Thus, if wind is involved in the propagation of amphibian declines, it is through a complex set of processes. Resumen: Exploramos la relación entre las declinaciones de anfibios y las variaciones climáticas en Colorado, E.U.A., Puerto Rico, Costa Rica/Panamá y Queensland, Australia por medio de dos fuentes de información: resultados "sistema de reanálisis" del Centro Nacional de Predicción Ambiental y datos de estaciones área-promedio. El sistema de reanálisis combina observaciones de aeroplanos, estaciones terrestres, satélites, barcos y globos climatológicos, con resultados de un modelo de predicción climatológica para crear campos globales de variables atmosféricas. Los datos de estaciones fueron de temperatura y precipitación medidos con termómetros y pluviómetros en localidades fijas. Las temperaturas fueron casi normales en Colorado cuando ocurrieron las declinaciones en la década de 1970, mientras que las temperaturas en Centro América fueron mayores a lo normal, especialmente durante la época de sequía. Los datos de estaciones en Puerto Rico y Australia indicaron que la temperatura fue mayor a la normal durante el período de declinación de anfibios, pero un nuevo análisis no mostró una señal de temperatura tan clara. Aunque las declinaciones ocurrieron mientras las anomalías de temperatura y precipitación fueron grandes y de duración prolongada en algunas de las regiones, las anomalías no rebasaron el rango de variabilidad normal. Por lo tanto, es poco probable que el clima inusual, medido por estimaciones regionales de temperatura y precipitación, sea la causa directa de las declinaciones de anfibios, pero pudo haber contribuido indirectamente a ellas. Investigaciones previas notan que las declinaciones parecen haberse propagado de noroeste a sureste de Costa Rica a Panamá y de sureste a noreste en Queensland, Australia. El viento tiene el potencial de transportar patógenos que causan mortalidad de anfibios. La dirección promedio de los vientos superficiales tendió a ser paralela al camino de las declinaciones de anfibios de julio a octubre en Centro América y de mayo a julio en Australia. Sin embargo, la dirección del viento fue altamente variable y la tasa de propagación de declinaciones de anfibios fue mucho más lenta que la velocidad promedio del viento. Adicionalmente, el patógeno más probable es un hongo quítrido que no produce esporas resistentes a la desecación. Por tanto, si el viento está implicado en la propagación de declinaciones de anfibios, lo es por medio de un complejo conjunto de procesos. [source]

Wind and Spirit: A Theological Autobiography

DIALOG, Issue 3 2007
Nancey Murphy
First page of article [source]

Mortality dynamics and population regulation in Bemisia tabaci

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2005
Steven E. Naranjo
Abstract Natural mortality is an important determinant of the population dynamics of a species, and an understanding of mortality forces should aid in the development of better management strategies for insect pests. An in situ, observational method was used to construct cohort-based life tables for Bemisia tabaci (Gennadius) Biotype B (Homoptera: Aleyrodidae) over 14 generations on cotton in central Arizona, USA, from 1997 to 1999. In descending order, median marginal rates of mortality were highest for predation, dislodgment, unknown causes, egg inviability, and parasitism. The highest mortality occurred during the 4th nymphal stadium, and the median rate of immature survival over 14 generations was 6.6%. Predation during the 4th nymphal stadium was the primary key factor. Irreplaceable mortality was highest for predation and dislodgment, with the absence of these mortality factors leading to the greatest increases in estimated net reproduction. There was little evidence of direct or delayed density-dependence for any mortality factor. Wind, rainfall, and predator densities were associated with dislodgment, and rates of predation were related to densities of Geocoris spp., Orius tristicolor (White), Chrysoperla carnea s.l. Stephens, and Lygus hesperus Knight. Simulations suggest that immigration and emigration play important roles in site-specific dynamics by explaining departures from observed population trajectories based solely on endogenous reproduction and mortality. By a direct measurement of these mortality factors and indirect evidence of adult movement, we conclude that efficient pest management may be best accomplished by fostering greater mortality during the 4th stadium, largely through a conservation of predators and by managing immigrating adult populations at their sources. [source]

Factors controlling aggregation in a minimum and a conventionally tilled undulating field

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 5 2007
S. De Gryze
Summary Wind and water erosion induce breakdown of soil aggregates and loss of soil organic matter. Whereas most of the relations between aggregation and its driving factors have been established on a plot scale, these relations might be very different within an undulating landscape where both erosion (by wind or water) and deposition occur. The aim of this study was to investigate to what degree spatial patterns in soil variables influence spatial patterns in aggregation under different tillage intensities. We studied an agricultural field of about 3 ha in the silty region of Belgium. The site was split into a conventional tillage (CT) and a minimum tillage (MT) system. Within the field, 396 geo-referenced surface soil samples (0,5 cm) were taken and analyzed for organic matter content, quantity of aggregates and a number of other soil properties. Under CT, 28.5% of the total sample variation was explained by the occurrence of depositional areas, 20.8% by the amount of soil organic matter, and 13.8% by the presence of a clay-rich B horizon which surfaced due to progressive water and tillage erosion. Regression analysis revealed that 27% of the variation in the quantity of macroaggregates (>0.25 mm) was accounted for by these three factors. Under MT, 27.1% of the total sample variation was related to the surface cover of Tertiary sand, 22.6% to the amount of soil organic matter, and 13% to erodibility. These three factors explained 53% of the variation in the quantity of macroaggregates. In the CT system, the correlation between grass- or maize- carbon and the quantity of macroaggregates was strongly linked to erodibility, while this was not the case in the MT system. We concluded that at this site, macroaggregation is dominated by landscape-scale processes (such as water or tillage erosion) rather than determined by the commonly considered local variables (such as small variations in texture or organic matter content). [source]

Interaction between wind-induced seiches and convective cooling governs algal distribution in a canyon-shaped reservoir

FRESHWATER BIOLOGY, Issue 7 2007
RAFAEL MARCÉ
Summary 1. Wind is considered the dominant factor controlling phytoplankton distribution in lentic environments. In canyon-shaped reservoirs, wind tends to blow along the main axis generating internal seiches and advective water movements that jointly with biological features of algae can produce a heterogeneous phytoplankton distribution. Turbulence generated by wind stress and convection will also affect the vertical distribution of algae, depending on their sinking properties. 2. We investigated the vertical and horizontal distribution of phytoplankton during the stratification period in Sau Reservoir (NE Spain). Sites along the main reservoir axis were sampled every 4 h for 3 days, and profiles of chlorophyll- a and temperature were made using a fluorescent FluoroProbe, which can discriminate among the main algal groups. Convective and wind shear velocity scales, and energy dissipation were calculated from meteorological data, and simulation experiments were performed to describe non-measured processes, like vertical advection and sinking velocity of phytoplankton. 3. Wind direction changed from day to night, producing a diel thermocline oscillation and an internal seiche. Energy dissipation was moderate during the night, and mainly attributed to convective cooling. During the day the energy dissipation was entirely attributed to wind shear, but values indicated low turbulence intensity. 4. The epilimnetic algal community was mainly composed of diatoms and chlorophytes. Chlorophytes showed a homogeneous distribution on the horizontal and vertical planes. Diatom horizontal pattern was also homogeneous, because the horizontal advective velocities generated by wind forcing were not high enough to develop phytoplankton gradients along the reservoir. 5. Diatom vertical distribution was heterogeneous in space and time. Different processes dominated in different regions of the reservoir, due to the interaction between seiching and the daily cycle of convective-mediated turbulence. As the meteorological forcing followed a clear daily pattern, we found very different diatom sedimentation dynamics between day and night. Remarkably, these dynamics were asynchronous in the extremes of the seiche, implying that under the same meteorological forcing a diatom population can show contrasting sedimentation dynamics at small spatial scales (approximately 103 m). This finding should be taken into account when interpreting paleolimnological records from different locations in a lake. 6. Vertical distribution of non-motile algae is a complex process including turbulence, vertical and horizontal advection, variations in the depth of the mixing layer and the intrinsic sinking properties of the organisms. Thus, simplistic interpretations considering only one of these factors should be regarded with caution. The results of this work also suggest that diatoms can persist in stratified water because of a synergistic effect between seiching and convective turbulence. [source]

Wind, Fire and Water: Renewable Energy and Birds Proceedings of the British Ornithologists' Union Annual Spring Conference 2005 University of Leicester, 1,3 April 2005

IBIS, Issue 2006
ROWENA H. W. LANGSTON Guest Editor
No abstract is available for this article. [source]

Opening address to Wind, Fire and Water: Renewable Energy and Birds

IBIS, Issue 2006
ELLIOT MORLEY
First page of article [source]

Characteristics of wind variations on Jeju Island, Korea

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2010
Kyungnam Ko
Abstract In order to clarify the long-term variability of the wind in complex terrain, an investigation was conducted on Jeju Island, Korea. The four coastal areas and the three mountainous areas were selected and wind data for 8,11 years from meteorological observatories were collected for this work. Inter-annual variations, monthly variations and diurnal variations in wind characteristics were calculated from the long-term wind data. As a result, it was found that wind speed is higher in the winter season while it is lower in the summer season. Wind at all sites blew strongly in the daytime and weakly at night. Also, wind energy and the range of variation in wind energy varied significantly from region to region on Jeju Island. Inter-annual variations in wind energy on Jeju Island occurred a little greater than seen in the results of earlier works conducted in other place. Copyright © 2009 John Wiley & Sons, Ltd. [source]

How do wind velocity and light intensity influence host-location success in Cotesia glomerata (Hym., Braconidae)?

JOURNAL OF APPLIED ENTOMOLOGY, Issue 3 2001

Wind and light are major climatic factors which affect host-location process in parasitoids, but these environmental effects have not been studied thoroughly. Wind-tunnel experiments were designed to dissect how changes in wind velocity and light intensity influence flight initiation, flight orientation and host-searching efficiency in Cotesia glomerata. This study uncovers the influences of changes in wind velocity and light intensity on different phases of host-location process in the parasitoid. These results suggest that a cloudy and/or windy weather may reduce the success of host location by C. glomerata because such conditions suppress flight initiation, cause failure to orientate flights to the herbivore-infested plant and hamper host-searching activity on the plant. [source]

Hereditary Bone and Joint Disease in the Dog

JOURNAL OF SMALL ANIMAL PRACTICE, Issue 6 2006
Neil Burton
Hereditary Bone and Joint Disease in the Dog Joe Morgan, Alinda Wind & Autumn Davidson Published by Manson Publishing, 2003. Hardback, 328 pages Price £61.00. ISBN 3-87706-548-1 [source]

Reflux symptoms in wind instrument players

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2010
G. CAMMAROTA
Aliment Pharmacol Ther,31, 593,600 Summary Background, An occupation-related susceptibility of orchestral wind instrument players to gastro-oesophageal reflux was hypothesized. Aim, To compare reflux symptoms reported by wind instrument players with those reported by players of other instruments. Methods, A questionnaire was distributed to 1083 musicians (414 wind instrument players and 669 players of other instruments) from 21 Italian orchestras to obtain information on reflux symptoms in the year preceding the survey together with selected individual characteristics and lifestyle habits. Crude and adjusted prevalence rate ratios (PRR) were computed by a model including gender, age, body mass index, smoking status, alcohol consumption and other confounding factors. Results, Wind instrument players reported a higher prevalence of heartburn in the previous year than the other instrument players (adjusted PRR 1.23, CI 95% 1.04,1.46). Wind instrument players also reported higher, although not fully significant, prevalence of regurgitation (adjusted PRR 1.22, CI 95% 0.97,1.54). Flute and double-reed instrument players seem to carry a higher risk of reflux symptoms. Conclusions, Wind instrument players reported a prevalence of typical reflux symptoms higher than other instrument players. [source]

Plant spatial arrangement affects projected invasion speeds of two invasive thistles

OIKOS, Issue 9 2010
Katherine M. Marchetto
The spatial arrangement of plants in a landscape influences wind flow, but the extent that differences in the density of conspecifics and the height of surrounding vegetation influence population spread rates of wind dispersed plants is unknown. Wind speeds were measured at the capitulum level in conspecific arrays of different sizes and densities in high and low surrounding vegetation to determine how these factors affect wind speeds and therefore population spread rates of two invasive thistle species of economic importance, Carduus acanthoides and C. nutans. Only the largest and highest density array reduced wind speeds at a central focal thistle plant. The heights of capitula and surrounding vegetation also had significant effects on wind speed. When population spread rates were projected using integrodifference equations coupling previously published demography data with WALD wind dispersal models, large differences in spread rates resulted from differences in average horizontal wind speeds at capitulum height caused by conspecific density and surrounding vegetation height. This result highlights the importance of spatial structure for the calculation of accurate spread rates. The management implication is that if a manager has time to remove a limited number of thistle plants, an isolated thistle growing in low surrounding vegetation should be targeted rather than a similar sized thistle in a high density population with high surrounding vegetation, if the objective is to reduce spread rates. [source]

Leaning into the Wind: A Structural VAR Investigation of UK Monetary Policy,

OXFORD BULLETIN OF ECONOMICS & STATISTICS, Issue 5 2005
Andrew Mountford
Abstract This paper adapts Uhlig's [Journal of Monetary Economics (2005) forthcoming] sign restriction identification methodology to investigate the effects of UK monetary policy using a structural vector autoregression (VAR). It shows that shocks which can reasonably be described as monetary policy shocks have played only a small role in the total variation of UK monetary and macroeconomic variables. Most of the variation in UK monetary variables has been due to their systematic reaction to other macroeconomic shocks, namely non-monetary aggregate demand, aggregate supply, and oil price shocks. We also find, without imposing any long run identifying restrictions, that aggregate supply shocks have permanent effects on output. [source]

Mit Pedalkraft gegen Berge und Wind.

PHYSIK IN UNSERER ZEIT (PHIUZ), Issue 6 2007
Fahrradfahren
Abstract Die Steigung der Fahrbahn bestimmt die Zusammensetzung der Fahrwiderstände und ist damit von großer Bedeutung für die Taktik eines Radrennens. Da sich an steilen Anstiegen das Fahren im Windschatten nicht mehr lohnt, kommt es dort zum Showdown unter den Favoriten. Leichtgewichtige Fahrer sind hier im Vorteil, wie einfache allometrische Überlegungen zeigen. Aus denselben Gründen hätten Schwergewichte auf Gefällestrecken zwar Vorteile, die sie aber im Allgemeinen wegen der engen Kurven und begrenzter Haftreibung nicht voll ausnutzen können. Je nach Streckenführung kann beim Einzelzeitfahren der Wind der ärgste Widersacher des Radfahrers sein. Modellrechnungen zeigen, wie sich der Wind je nach seiner Richtung auswirkt und erteilen der auf den ersten Blick nahe liegenden Idee zur Kompensierung des Windes kreisförmige Rennstrecken einzuführen, eine klare Absage. [source]

Electrophilic Fluorocyclization of Allyl Silanes,

ANGEWANDTE CHEMIE, Issue 38 2009
Susan
Frischen Wind in die Verwendung fluorierter Hetero- und Carbocyclen als Pharmaka und Agrochemikalien bringen allgemeine Fluorcyclisierungen. Bei Allylsilanen gelang nun die selektive Fluorierung-Cyclisierung mit N-F-Reagentien zu cis - und trans -substituierten fluorierten Heterocyclen (siehe Schema). Die Art der Silylgruppe entscheidet darüber, ob die konkurrierende Fluordesilylierung abläuft oder nicht. [source]

Front and Back Covers, Volume 26, Number 2.

ANTHROPOLOGY TODAY, Issue 2 2010
April 2010
Front cover caption, volume 26 issue 2 A positive, albeit anthropomorphized, view of badgers appears in this illustration for the original edition of the children's classic Wind in the willows. Badgers are shortly to be culled in north Pembrokeshire as part of a Welsh Assembly Government campaign against bovine TB. Pat Caplan's article in this issue discusses the arguments around the cull and the reasons behind the varying positions held by local people on this issue. Back cover caption Witchcraft and Child Sacrifice Above: a poster (supported by NGOs including Save the Children Uganda) against ,child sacrifice' in Uganda, a current topic of concern both to Ugandans and to anthropologists who have criticized media representations of this issue. Below: a Save the Children poster publicizing the main principles of the United Nations Convention on the Rights of the Child, signed by 191 countries. These rights include, among others, the rights to: be protected from being hurt or badly treated in any way; not be kidnapped or sold; be protected from being taken advantage of or exploited in any way; not be punished in a cruel or hurtful way. The article by Pat Caplan in this issue discusses a number of recent BBC broadcasts focused on allegations of witchcraft and child sacrifice, and asks what anthropologists have to offer in terms of understanding such topics. Caplan notes that they can not only contribute their knowledge of the occult in many societies, but also contextualize this realm in terms of historical processes and more material concerns. In addition, anthropologists can suggest links between apparently disparate issues and thereby go beyond surface manifestations. While anthropologists have no monopoly on truth claims, they can sometimes offer alternative explanations and show that things are not always the way they first seem. In order to play an effective role as public intellectuals in this regard, anthropologists need to be willing to grapple pro-actively with such matters of public concern, not least by engaging constructively with the media. [source]

Wind dispersal in freshwater wetlands: Knowledge for conservation and restoration

APPLIED VEGETATION SCIENCE, Issue 2 2006
Merel B. Soons
van der Meijden (1990) for taxa; Schaminée et al. (1995; 1996) and Stortelder et al. (1999) for syntaxa Abstract Questions: For wetland plants, dispersal by wind is often overlooked because dispersal by water is generally assumed to be the key dispersal process. This literature review addresses the role of seed dispersal by wind in wetlands. Why is wind dispersal relevant in wetlands? Which seeds are dispersed by wind and how far? And how can our understanding of wind dispersal be applied to wetland conservation and restoration? Methods: Literature review. Results and conclusions: Wind is a widely available seed dispersal vector in wetlands and can transport many seeds over long distances. Unlike water, wind can transport seeds in all directions and is therefore important for dispersal to upstream wetlands and to wetlands not connected by surface water flows. Wind dispersal transports seeds to a wider range of sites than water, and therefore reaches more sites but with lower seed densities. Many wetland plant species have adaptations to facilitate wind dispersal. Dispersal distances increase with decreasing falling velocity of seeds, increasing seed release height and selective release mechanisms. Depending on the adaptations, seeds may be dispersed by wind over many km or only a few m. The frequency of long-distance wind dispersal events depends on these adaptations, the number of produced seeds, the structure of the surrounding vegetation, and the frequency of occurrence of suitable weather conditions. Humans reduce the frequency of successful long-distance wind dispersal events in wetlands through wetland loss and fragmentation (which reduce the number and quality of seeds) and eutrophication (which changes the structure of the vegetation so that seed release into the wind flow becomes more difficult). This is yet another reason to focus on wetland conservation and restoration measures at increased population sizes, prevention of eutrophication, and the restoration of sites at short distances from seed sources. [source]

Sonderlösungen bei der Tragwerksplanung auf der Grundlage der neuen Normen , Klimatische Einwirkungen

BAUTECHNIK, Issue 3 2005
Hans-Jürgen Niemann Prof. em.
Der folgende Beitrag befaßt sich mit den klimatischen Einwirkungen auf weit gespannte Dächer. Im Zentrum stehen die Windlasten. Die Angaben der Norm lassen sich durch Sonderuntersuchungen zuschärfen, soweit die Regelungen das nahe legen und der zusätzliche Aufwand gerechtfertigt ist. Das gilt sowohl für das Windklima am Bauwerksstandort als auch für die aerodynamischen Beiwerte, für die im allgemeinen Windkanalversuche die Grundlage bilden. In einer neuen Norm, der DIN 1055 Teil 100: "Grundlagen der Tragwerksplanung, Sicherheitskonzept und Bemessungsregeln", werden erstmalig die Anforderungen an die Tragsicherheit und Gebrauchstauglichkeit einer Konstruktion formuliert und festgelegt. Sie definiert die Lastannahmen als Teil des Sicherheitskonzepts, legt die Anforderungen an das Lastniveau fest und bestimmt so die Spielräume für eine Zuschärfung der Lastannahmen durch Sonderuntersuchungen für ein bestimmtes Bauprojekt. Hinzu kommen einzelne Öffnungsklauseln, die in den Normen für Wind- und Schneelasten vorgesehen sind. Der Beitrag stellt die Rahmenbedingungen für eine Optimierung der Lastannahmen dar. Special solutions in structural design on the basis of the new design codes , climatic actions. The following contribution deals with climatic actions on large lightweight roofs of stadia. The focus is on the wind loads. In some cases, it becomes necessary or advantageous to provide more precise design wind loads compared to the code provisions. This applies to the local wind climate as well as to the aerodynamic coefficients. The framework for such investigations is established by the requirements set by the code DIN 1055-100: Basis of design, with regard to structural safety and reliability, and by those basic stipulations in the wind loading code which may not be altered. The author presents and discusses the framework for optimised design wind loads. [source]

Themen Heft 3/2008

BETON- UND STAHLBETONBAU, Issue 2 2008
Article first published online: 30 JAN 200
F. Fingerloos, G. Timm Hinweise zu Wind-, Schnee und Silolasten in DIN 1055 F. Fingerloos, J. Grünberg Die Parkhauslasten in DIN 1055-3 S. Lay, P. Rucker, C. Brandes, J. Käppler, R. Boese Lebensdauerbemessung , Baustein für die Instandsetzungsplanung am Beispiel eines Parkhauses M. Schlaich, M. El Zareef Infraleichtbeton [source]

Southeast Alaska: oceanographic habitats and linkages

JOURNAL OF BIOGEOGRAPHY, Issue 3 2009
Thomas Weingartner
Abstract We provide an overview of the physical oceanographic and geological processes that affect marine biological habitats and production in the marine waters throughout the archipelago and continental shelf of Southeast Alaska. Given the paucity of regional data, our overview summarizes work done in adjacent regions of the Gulf of Alaska shelf and basin, and draws on research carried out in similar settings elsewhere. The geological setting, which critically influences the regional meteorology and oceanography, includes a narrow continental shelf, deep channels that permeate the archipelago, fjords, glaciers and a rugged, mountainous coast. The large-scale meteorology is influenced primarily by seasonal variations in the intensity and position of the Aleutian Low. Winds, freshwater runoff, tides and cross-shelf exchange control the regional oceanography. The large-scale flow field advects mass, heat, salt, nutrients and planktonic organisms northward from British Columbia (and even further south) to the northern Gulf of Alaska along the slope, shelf, and within the channels of Southeast Alaska. The deep channels permeating the island archipelago and narrow continental shelf facilitate communication between basin and interior waters. Water properties and flow fields are subject to large annual variations in response to similarly large variations in winds and coastal freshwater discharge. The complex geological setting leads to large spatial heterogeneity in the physical processes controlling the local circulation fields and mixing, thereby creating numerous and diverse marine biological habitats. These various circulation and mixing processes modify substantially Southeast Alaska water masses and thus influence marine ecosystem processes downstream over the northern and western Gulf of Alaska shelf. [source]

Winds from massive stars: implications for the afterglows of , -ray bursts

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2001
Enrico Ramirez-Ruiz
Recent observations suggest that long-duration , -ray bursts (GRBs) and their afterglows are produced by highly relativistic jets emitted in core-collapse explosions. The pre-explosive ambient medium provides a natural test for the most likely progenitors of GRBs. Those stars that shed their envelopes most readily have short jet crossing times and are more likely to produce a GRB. We construct a simple computational scheme to explore the expected contribution of the presupernova ejecta of single Wolf,Rayet (WR) stars to the circumstellar environment. Using detailed stellar tracks for the evolution of massive stars, we discuss the effects that the initial main-sequence mass, metallicity, rotation and membership in a binary system have on the ambient medium. We extend the theory of GRB afterglows in winds to consider the effect of the relativistic fireball propagating through the WR ejecta. Specific predictions are made for the interaction of the relativistic blast wave with the density bumps that arise when the progenitor star rapidly loses a large fraction of its initial mass or when the ejected wind interacts with the external medium and decelerates. A re-brightening of the afterglow with a spectrum redder than the typical synchrotron spectrum (as seen in GRB 970508, GRB 980326 and GRB 000911) is predicted. We also calculate the luminosity of the reflected echo that arises when circumstellar material Compton-scatters the prompt radiation, and examine the spectral signatures expected from the interaction of the GRB afterglow with the ejected medium. [source]

Au vent de l'éventuel: Following the Winds of Chance

AMERICAN ANTHROPOLOGIST, Issue 1 2005
NADINE WANONO
No abstract is available for this article. [source]

Winds of time and place: How context has affected a 50,year marriage

PERSONAL RELATIONSHIPS, Issue 3 2003
George Levinger
To examine the effects of contexts on a relationship, we consider the case of our own 50,year marriage and its preliminaries. We employ a three,level conception of a couple's environment. The macrocontext refers to the prevailing cultural winds in a society that affect all its residents during any given historical era. The mesocontext pertains to the settings in which a particular relationship operates, such as its family and other social networks, physical habitats, work settings, or institutional associations, often chosen by the partners themselves. The microcontext is the pair's own intimate environment, constructed over time by the partners' unique interactions. Each of these contexts has affected us. We describe and analyze instances of luck, choice, and dyadic interaction in our 52,year relationship. [source]

Generation of tree movement sound effects

COMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 5 2005
Katsutsugu Matsuyama
Abstract This paper presents a method for automatically generating sound effects for an animation of branches and leaves moving in the wind. Each tree is divided into branches and leaves, and an independent sound effect generation process is employed for each element. The individual results are then compounded into one sound effect. For the branches, we employ an approach based on the frequencies of experimentally obtained Karman vortex streets. For the leaves, we use the leaf blade state as the input and assume a virtual musical instrument that uses wave tables as the sound source. All computations can be performed independently for each frame step. Therefore, each frame step can be executed on completion of the animation step. The results of the implementation of the approach are presented and it is shown that the process offers the possibility of real-time operation through the use of parallel computing techniques. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Interactive animation of cloth-like objects in virtual reality

COMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 1 2001
Mark Meyer
Abstract Modeling and animation of cloth have experienced important developments in recent years. As a consequence, complex textile models can be used to realistically drape objects or human characters in a fairly efficient way. However, real-time realistic simulation remains a major challenge, even if applications are numerous, from rapid prototyping to e-commerce. In this paper, we present a stable, real-time algorithm for animating cloth-like materials. Using a hybrid explicit/implicit algorithm, we perform fast and stable time integration of a physically based model with rapid collision detection and response, as well as wind or liquid drag effects to enhance realism. We demonstrate our approach through a series of examples in virtual reality environments, proving that real-time animation of cloth, even on low-end computers, is now achievable. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Physically Guided Animation of Trees

COMPUTER GRAPHICS FORUM, Issue 2 2009
Ralf Habel
Abstract This paper presents a new method to animate the interaction of a tree with wind both realistically and in real time. The main idea is to combine statistical observations with physical properties in two major parts of tree animation. First, the interaction of a single branch with the forces applied to it is approximated by a novel efficient two step nonlinear deformation method, allowing arbitrary continuous deformations and circumventing the need to segment a branch to model its deformation behavior. Second, the interaction of wind with the dynamic system representing a tree is statistically modeled. By precomputing the response function of branches to turbulent wind in frequency space, the motion of a branch can be synthesized efficiently by sampling a 2D motion texture. Using a hierarchical form of vertex displacement, both methods can be combined in a single vertex shader, fully leveraging the power of modern GPUs to realistically animate thousands of branches and ten thousands of leaves at practically no cost. [source]

Wind projection basis for real-time animation of trees

COMPUTER GRAPHICS FORUM, Issue 2 2009
Julien Diener
This paper presents a real-time method to animate complex scenes of thousands of trees under a user-controllable wind load. Firstly, modal analysis is applied to extract the main modes of deformation from the mechanical model of a 3D tree. The novelty of our contribution is to precompute a new basis of the modal stress of the tree under wind load. At runtime, this basis allows to replace the modal projection of the external forces by a direct mapping for any directional wind. We show that this approach can be efficiently implemented on graphics hardware. This modal animation can be simulated at low computation cost even for large scenes containing thousands of trees. [source]

An application portal for collaborative coastal modeling

CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 12 2007
Chongjie Zhang
Abstract We describe the background, architecture and implementation of a user portal for the SCOOP coastal ocean observing and modeling community. SCOOP is engaged in the real-time prediction of severe weather events, including tropical storms and hurricanes, and provides operational information including wind, storm surge and resulting inundation, which are important for emergency management. The SCOOP portal, built with the GridSphere Framework, currently integrates customized Grid portlet components for data access, job submission, resource management and notification. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Low Recruitment of Trees Dispersed by Animals in African Forest Fragments

CONSERVATION BIOLOGY, Issue 6 2001
N. J. Cordeiro
We compared adult and juvenile trees in forest transects in a 3500,ha submontane forest with those in four forest fragments of 521, 30, 9, and 0.5 ha. Preliminary results show that recruitment of seedlings and juveniles of 31 animal-dispersed tree species was more than three times greater in continuous forest and large forest fragments (,30 ha) than in small forest fragments (,9 ha), whereas recruitment of eight wind- and gravity-dispersed trees of the forest interior was unaffected. Recruitment of 10 endemic, animal-dispersed tree species was 40 times lower in small fragments than in continuous forest or large fragments. Counts of diurnal primates and birds in all five sites indicated that frugivorous species have declined with decreasing fragment size. These results are consistent with the idea that loss of dispersal agents depresses tree recruitment in the course of forest fragmentation. Resumen: Investigamos los efectos de la fragmentación del bosque en la desaparición de animales frugívoros y el reclutamiento de árboles dispersados por animales y viento en parches de bosques de 80 años de edad en las montañas del este de Usambara, Tanzania. Comparamos árboles adultos y juveniles en transectos de bosque en un bosque submontañoso de 3500 ha con transectos de cuatro fragmentos de bosque de 521, 30, 9 y 0.5 ha. Los resultados preliminares muestran que el reclutamiento de plántulas y juveniles especies de árboles dispersados por animales fue tres veces mayor en el bosque continuo y fragmentos grandes (,30 ha) que en fragmentos pequeños (,9 ha), mientras que el reclutamiento de ocho árboles dispersados por viento y gravedad del interior del bosque no fue afectado. El reclutamiento de 10 especies endémicas de árboles dispersados por animales fue 40 veces menor en los fragmentos pequeños que en el bosque continuo o en los fragmentos grandes. Los conteos de primates diurnos y aves en los cinco sitios indican que las especies frugívoras han disminuido con la disminución del tamaño del fragmento. Estos resultados son consistentes con la idea de que la pérdida de los agentes dispersores deprime el reclutamiento de los árboles en el transcurso de la fragmentación del bosque. [source]