Home About us Contact
|
Home About us Contact | ||
|
|
||
Several Locations (several + locations)
Selected AbstractsFeather deuterium measurements reveal origins of migratory western loggerhead shrikes (Lanius ludovicianus excubitorides) wintering in MexicoDIVERSITY AND DISTRIBUTIONS, Issue 2 2007Guillermo E. Pérez ABSTRACT Understanding the winter distributions of migrant birds is important because productivity and recruitment are influenced by conditions at several locations and periods in the life cycle of individuals. The western loggerhead shrike, Lanius ludovicianus excubitorides, is a threatened species in Canada, and its decline is attributed to potential limitations on the wintering grounds. We examined patterns of stable-hydrogen isotope (,D) distributions in feathers of loggerhead shrikes, primarily of L. l. excubitorides, during winter at three regions in north and central Mexico, to establish relative abundance and origins of migrants. We also investigated potential movements of Mexican winter resident individuals. Using shrike museum specimens of known summer provenance, a shrike deuterium base map for Mexico was developed from isotopic measurement of feathers of resident shrikes and use of a recently established feather base map for raptors in North America. Stable hydrogen isotope analyses of inner secondary feather (s9) of all loggerhead shrikes examined in Mexico during winter indicated that north-central (Region A), north-eastern (Region B) and south-central (Region C) sites in Mexico consisted of 28.1%, 73.7% and 63.8% of migrant individuals from northern breeding grounds, respectively. Isotopic evidence suggested movements of a few local residents birds (7.9%) into the Chihuahuan desert from south-western USA and north-eastern Mexico to winter. [source] An experimental investigation of water level effects on the dynamic behaviour of a large arch damEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2001Jean Proulx Abstract The need for full-scale dynamic tests, which are recognized as the most reliable method to evaluate a structure's vibration properties, is increasing as new analysis techniques are developed that take into account the complex interaction phenomenons that occur in dam,reservoir,foundation systems. They are extremely useful to obtain reliable data for the calibration of newly developed numerical methods. The Earthquake Engineering and Structural Dynamics Research Center (CRGP) at the University of Sherbrooke has been developing and applying dynamic testing methods for large structures in the past 10 years. This paper presents the experimental evaluation of the effects of the varying water level on the dynamic response of the 180 m Emosson arch dam in Switzerland. Repeated forced-vibration tests were carried out on the dam during four different periods of the reservoir's filling cycle during a one-year span. Acceleration and hydrodynamic pressure frequency responses were obtained at several locations while the dam was subjected to horizontal harmonic loading. The variation of the resonant frequencies as a function of the reservoir level is investigated. A summary of the ongoing numerical correlation phase with a three-dimensional finite element model for the dam,reservoir,foundation system is also presented. Copyright © 2001 John Wiley & Sons, Ltd. [source] Isolation and properties of methanesulfonate-degrading Afipia felis from Antarctica and comparison with other strains of A. felisENVIRONMENTAL MICROBIOLOGY, Issue 1 2005S. Azra Moosvi Summary Three novel strains of methylotrophic Afipia felis were isolated from several locations on Signy Island, Antarctica, and a fourth from estuary sediment from the River Douro, Portugal. They were identified as strains of the ,-2 proteobacterium A. felis by 16S rRNA gene sequence, analysis., Two, strains, tested, were, shown to contain the fdxA gene, diagnostic for A. felis. All strains grew with methanesulfonate (and two strains with dimethylsulfone) as sole carbon substrate. Growth on methanesulfonate required methanesulfonate monooxygenase (MSAMO), using NADH as the reductant and stimulated by reduced flavin nucleotides and Fe(II). Polymerase chain reaction amplification of DNA from an Antarctic strain showed a typical msmA gene for the ,-hydroxylase of MSAMO, and both Antarctic and Portuguese strains contained mxaF, the methanol dehydrogenase large subunit gene. This is the first report of methanesulfonate-degrading bacteria from the Antarctic and of methylotrophy in Afipia, and the first description of any bacterium able to use both methanesulfonate and dimethylsulfone. In contrast, the type strain of A. felis DSM 7326T was not methylotrophic, but grew in defined mineral medium with a wide range of single simple organic substrates. Free-living Afipia strains occurring widely in the natural environment may be significant as methylotrophs, degrading C1 -sulfur compounds, including the recalcitrant organosulfur compound methanesulfonate. [source] A dynamic simulation model for powdery mildew epidemics on winter wheat,EPPO BULLETIN, Issue 3 2003V. Rossi A system dynamic model for epidemics of Blumeria graminis (powdery mildew) on wheat was elaborated, based on the interaction between stages of the disease cycle, weather conditions and host characteristics. The model simulates the progress of disease severity, expressed as a percentage of powdered leaf area, on individual leaves, with a time step of one day, as a result of two processes: the growth of fungal colonies already present on the leaves and the appearance of new colonies. By means of mathematical equations, air temperature, vapour pressure deficit, rainfall and wind are used to calculate incubation, latency and sporulation periods, the growth of pathogen colonies, infection and spore survival. Effects of host susceptibility to infection, and of leaf position within the plant canopy, are also included. Model validation was carried out by comparing model outputs with the dynamics of epidemics observed on winter wheat grown at several locations in northern Italy (1991,98). Simulations were performed using meteorological data measured in standard meteorological stations. As there was good agreement between model outputs and actual disease severity, the model can be considered a satisfactory simulator of the effect of environmental conditions on the progress of powdery mildew epidemics. [source] Hydrological importance of an unusual hazard in a mountainous basin: flood and landslideHYDROLOGICAL PROCESSES, Issue 14 2006Umesh K. Haritashya Abstract The Bhagirathi River, a proglacial melt water stream of the Gangotri Glacier, is the principal source of the Ganges river system. The upper part of the basin lies in the high altitude region of the Garhwal Himalayas and is extensively covered by glaciers. We provide hydro-meteorological insight into a severe storm that produced unusual high rains in June 2000 in the uppermost part of the Bhagirathi River. This storm was concentrated upstream of Gangotri town and triggered landslides/rockslides at several locations between the glacier snout and Gangotri town. One of the major rockslides blocked the Bhagirathi River at Bhujbas, about 3 km downstream of the Gangotri Glacier snout, creating an artificial lake at this location. High stream flow in the river, generated by rapid runoff response from mountain slopes along with melt runoff from the glacier, quickly increased the level of water stored in the artificial lake. Daily rainfall in this region rarely exceeds 10 mm, while total rainfall during this 6-day storm was 131·5 mm. This unusual rain event occurred during the tourist season in June, consequently trapping a large number of tourists and vendors in this area. Sudden release of stored water generated floods that created havoc downstream of the artificially created lake. This paper presents the hydrological and meteorological information related to such an unusual and devastating event observed in the high altitude region of the Himalayas. Copyright © 2006 John Wiley & Sons, Ltd. [source] An analysis of liquid CO2 drop formation with and without hydrate formation in static mixersAICHE JOURNAL, Issue 10 2010Hideo Tajima Abstract The formation process of CO2 drops in various types of Kenics Static Mixers was analyzed from the perspective of energy dissipation in the mixer, focusing on the formation of drop surfaces. Experimental studies on CO2 drop formation were conducted under varying temperatures, pressure, and flow rates, with and without hydrate formation. Analysis of the CO2 drop size and distribution at several locations within the static mixer was conducted, as of pressure drop in the mixer, to determine dissipation energies. In all the experimental conditions, by considering the surface energy for hydrate formation, the energy required for the formation of CO2 drops correlated well with total energy dissipation by mixer flow, which is represented by a pressure drop along the mixer. This process has important applications to the formation of liquid CO2 for ocean disposal as a countermeasure to global warming. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] STOCHASTIC WATER QUALITY ANALYSIS USING RELIABILITY METHOD,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2001Kun-Yeun Han ABSTRACT: This study developed a QUAL2E-Reliability Analysis (QUAL2E-RA) model for the stochastic water quality analysis of the downstream reach of the main Han River in Korea. The proposed model is based on the QUAL2E model and incorporates the Advanced First-Order Second-Moment (AFOSM) and Mean-Value First-Order Second-Moment (MFOSM) methods. After the hydraulic characteristics from standard step method are identified, the optimal reaction coefficients are then estimated using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) method. Considering variations in river discharges, pollutant loads from tributaries, and reaction coefficients, the violation probabilities of existing water quality standards at several locations in the river were computed from the AFOSM and MFOSM methods, and the results were compared with those from the Monte Carlo method. The statistics of the three uncertainty analysis methods show that the outputs from the AFOSM and MFOSM methods are similar to those from the Monte Carlo method. From a practical model selection perspective, the MFOSM method is more attractive in terms of its computational simplicity and execution time. [source] Subsurface drainage for reversing degradation of waterlogged saline landsLAND DEGRADATION AND DEVELOPMENT, Issue 6 2006D. P. Sharma Abstract In irrigated agriculture of arid and semiarid regions waterlogging coupled with salinity is a serious problem. Experimental evidence at several locations has led to the realization that subsurface drainage is an essential intervention to reverse the processes of land degradation responsible for the formation of waterlogged saline lands. This paper presents the results of a study conducted from 1995 to 2000 to evaluate the impacts of subsurface drainage on soil properties, groundwater-table behaviour and crop productivity in a waterlogged saline area of 2200,ha. A subsurface drainage system was installed at 1·6,m depth with 60,m drain spacing covering an area of 1200,ha (23 blocks) during 1997,99 and compared with an undrained block of 1000,ha. Subsurface drainage facilitated the reclamation of waterlogged saline lands and a decrease in the soil salinity (ECe, dS,m,1) that ranged from 16·0 to 66·3,per,cent in different blocks. On average, 35·7,per,cent decrease in salt content was observed when compared with the initial value. Provision of subsurface drainage controlled the water-table below the root zone during the monsoon season and helped in bringing the soil to optimum moisture content for the sowing of winter crops. In the drained area, the increase in yields of different crops ranged from 18·8 to 27·6,per,cent. However, in the undrained area the yield of different crops decreased due to the increased waterlogging and soil salinity problems. Overall the results indicated that investment in subsurface drainage is a viable option for reversing the land degradation of waterlogged saline lands in a monsoon climate. Copyright © 2006 John Wiley & Sons, Ltd. [source] The terminal nerve and its relation with extrabulbar "olfactory" projections: Lessons from lampreys and lungfishesMICROSCOPY RESEARCH AND TECHNIQUE, Issue 1-2 2004Christopher S. Von BartheldArticle first published online: 29 NOV 200 Abstract The definition of the terminal nerve has led to considerable confusion and controversy. This review analyzes the current state of knowledge as well as diverging opinions about the existence, components, and definition of terminal nerves or their components, with emphasis on lampreys and lungfishes. I will argue that the historical terminology regarding this cranial nerve embraces a definition of a terminal nerve that is compatible with its existence in all vertebrate species. This review further summarizes classical and more recent anatomical, developmental, neurochemical, and molecular evidence suggesting that a multitude of terminalis cell types, not only those expressing gonadotropin-releasing hormone, migrate various distances into the forebrain. This results in numerous morphological and neurochemically distinct phenotypes of neurons, with a continuum spanning from olfactory receptor-like neurons in the olfactory epithelium to typical large ganglion cells that accompany the classical olfactory projections. These cell bodies may lose their peripheral connections with the olfactory epithelium, and their central projections or cell bodies may enter the forebrain at several locations. Since "olfactory" marker proteins can be expressed in bona fide nervus terminalis cells, so-called extrabulbar "olfactory" projections may be a collection of disguised nervus terminalis components. If we do not allow this pleiomorphic collection of nerves to be considered within a terminal nerve framework, then the only alternative is to invent a highly species- and stage-specific, and, ultimately, thoroughly confusing nomenclature for neurons and nerve fibers that associate with the olfactory nerve and forebrain. Microsc. Res. Tech. 65:13,24, 2004. © 2004 Wiley-Liss, Inc. [source] A study of the massive star-forming region M8 using images from the Spitzer Infrared Array CameraMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2010Dewangan Lokesh Kumar ABSTRACT We present photometry and images (3.6, 4.5, 5.8 and 8.0 ,m) from the Spitzer Infrared Array Camera (IRAC) of the star-forming region Messier 8 (M8). The IRAC photometry reveals ongoing star formation in the M8 complex, with 64 class 0/I and 168 class II sources identified in several locations in the vicinity of submm gas cores/clumps. Nearly 60 per cent of these young stellar objects (YSOs) occur in about seven small clusters. The spatial surface density of the clustered YSOs is determined to be about 10,20 YSOs pc,2. Fresh star formation by the process of ,collect and collapse' might have been triggered by the expanding H ii regions and winds from massive stars. IRAC ratio images are generated and studied in order to identify possible diagnostic emission regions in M8. The image of 4.5/8.0 ,m reveals a Br, counterpart of the optical Hourglass H ii region, while the ratio 8.0/4.5 ,m indicates PAH emission in a cavity-like structure to the east of the Hourglass. The ratio maps of 3.6/4.5, 5.8/4.5 and 8.0/4.5 ,m seem to identify PAH emission regions in the sharp ridges and filamentary structures seen east to west and north-east to south-west in the M8 complex. [source] Macaque,human interactions and the societal perceptions of macaques in SingaporeAMERICAN JOURNAL OF PRIMATOLOGY, Issue 10 2009John Chih Mun Sha Abstract Humans and long-tailed macaques (Macaca fascicularis) interface in several locations in Singapore. We investigated six of these interface zones to assess the level of conflict between the two species. We observed macaque-to-human interactions and distributed questionnaires to residents and visitors of nature reserves. We observed an average of two macaque-to-human interactions per hour at the sites, which included affiliative or submissive behaviors (46.9%), aggression (19.1%), taking food and other items (18.5%) searching bins, cars, and houses (13.4%), and nonaggressive contact (2.1%). Two-thirds of interactions occurred when a human was carrying food or food cues, and one-quarter occurred when a human provoked macaques. Only 8% of interactions occurred without a clear human-triggered context. Our interview showed one-third of respondents experienced nuisance problems from macaques. They had items taken from them (50.5%) and received threats (31.9%). Residents reported more nuisance problems than visitors, and their perceptions toward macaques differed. Residents were more aware of the consequences of food provisioning and that there were regulations against feeding. Residents fed macaques less and held more negative sentiments toward macaques. Nearly half of the interviewed people held neutral attitudes toward macaques and only 26.2% of respondents thought conflict with macaques warranted urgent action. Nearly two-thirds of the respondents supported education programs to ameliorate human,macaque conflict, and less than 15% supported removing or eradicating macaques. 87.6% felt that it is importance to conserve and protect macaques. Our results show that human,macaque conflict exists in Singapore, but that it may not be severe. Human behavior is largely responsible for macaque-to-human interactions, and thus could be lessened with management of human behavior in interface zones (i.e. restrict food carrying and provocation). Moreover, our interviews shows people living in Singapore value macaques, do not wish them entirely removed, prefer education-based solutions, and consider conservation and protection of them important. Am. J. Primatol. 71:825,839, 2009. © 2009 Wiley-Liss, Inc. [source] Delivery risk and the hedging role of optionsTHE JOURNAL OF FUTURES MARKETS, Issue 4 2002Donald Lien Multiple delivery specifications exist on nearly all commodity futures contracts. Sellers typically are allowed to deliver any of several grades of the underlying commodity and at any of several locations. On the delivery day, the futures price as such needs not converge to the spot price of the par-delivery grade at the par-delivery location, thereby imposing an additional delivery risk on hedgers. This article derives the optimal hedging strategy for a risk-averse hedger in the presence of delivery risk. In particular, it is shown that the hedger optimally uses options on futures for hedging purposes. This article provides a rationale for the hedging role of options when futures markets allow for multiple delivery specifications. © 2002 Wiley Periodicals, Inc. Jrl Fut Mark 22:339,354, 2002 [source] Climate change impacts on investment in crop sowing machinery,AUSTRALIAN JOURNAL OF AGRICULTURAL & RESOURCE ECONOMICS, Issue 2 2009Ross Kingwell A model of investment in crop sowing machinery is applied to wheat production under current and projected climatic conditions at several locations in south-western Australia. The model includes yield responses to time of sowing at each location given current and projected climatic conditions. These yield relationships are based on wheat growth simulation modelling that in turn draws on data from a down-scaled global circulation model. Wheat price distributions and cost of production data at each location, in combination with the time of sowing yield relationships are used to determine a farmer's optimal investment in crop sowing work rate under each climate regime. The key finding is that the impacts of climate change on profit distributions are often marked, yet mostly modest changes in investment in work rate form part of the profit-maximising response to climate change. The investment response at high versus low rainfall locations mostly involves increases and decreases in work rates, respectively. However, changes to investment in work rate within a broadly similar rainfall region are not always uniform. The impacts of climate change on investments in work rate at a particular location are shown to require knowledge of several factors, especially how climate change alters the pattern of yield response to the time of sowing at that location. [source] | ||||||||||||||||