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Distribution by Scientific Domains
Engineering21%
Life Sciences17%
Humanities and Social Sciences17%
Medical Sciences13%
Chemistry8%

Selected Abstracts

Refining Biodiversity Conservation Priorities

CONSERVATION BIOLOGY, Issue 6 2005
GRANT M. HARRIS
Bosque del Atlántico; percepción remota; priorización; SIG; sitios prioritarios para la conservación Abstract:,Although there is widespread agreement about conservation priorities at large scales (i.e., biodiversity hotspots), their boundaries remain too coarse for setting practical conservation goals. Refining hotspot conservation means identifying specific locations (individual habitat patches) of realistic size and scale for managers to protect and politicians to support. Because hotspots have lost most of their original habitat, species endemic to them rely on what remains. The issue now becomes identifying where this habitat is and these species are. We accomplished this by using straightforward remote sensing and GIS techniques, identifying specific locations in Brazil's Atlantic Forest hotspot important for bird conservation. Our method requires a regional map of current forest cover, so we explored six popular products for mapping and quantifying forest: MODIS continuous fields and a MODIS land cover (preclassified products), AVHRR, SPOT VGT, MODIS (satellite images), and a GeoCover Landsat thematic mapper mosaic (jpg). We compared subsets of these forest covers against a forest map based on a Landsat enhanced thematic mapper. The SPOT VGT forest cover predicted forest area and location well, so we combined it with elevation data to refine coarse distribution maps for forest endemic birds. Stacking these species distribution maps enabled identification of the subregion richest in threatened birds,the lowland forests of Rio de Janeiro State. We highlighted eight priority fragments, focusing on one with finer resolved imagery for detailed study. This method allows prioritization of areas for conservation from a region >1 million km2 to forest fragments of tens of square kilometers. To set priorities for biodiversity conservation, coarse biological information is sufficient. Hence, our method is attractive for tropical and biologically rich locations, where species location information is sparse. Resumen:,Aunque hay acuerdo generalizado sobre las prioridades de conservación a escalas mayores (i. e., sitios prioritarios para la conservación de la biodiversidad), los límites son muy gruesos como para definir metas de conservación prácticas. La refinación de la conservación de sitios prioritarios significa la identificación de localidades específicas (parches de hábitat individuales) de tamańo y escala realistas para ser protegidos por gestores y apoyados por políticos. Debido a que los sitios prioritarios han perdido la mayor parte de su hábitat original, las especies endémicas dependen del que permanece. Ahora el asunto es identificar donde están el hábitat y las especies. Logramos lo anterior mediante técnicas directas de percepción remota y de SIG para identificar localidades específicas importantes para la conservación de aves en el sitio prioritario Bosque del Atlántico en Brasil. Nuestro método requiere de un mapa regional de la cobertura forestal actual, así que exploramos seis productos populares para el mapeo y cuantificación de bosques: campos continuos MODIS y una cobertura de suelo MODIS (productos preclasificados), AVHRR, SPOT VGT, MODIS (imágenes de satélite) y un mosaico GeoCover Landsat thematic mapper (jpg). Comparamos subconjuntos de estas coberturas forestales con las de un mapa basado en un Landsat enhanced thematic mapper. La cobertura forestal SPOT VGT predijo bien la superficie y localización del bosque, así que lo combinamos con datos de altitud para refinar los mapas generales de distribución de aves endémicas de bosques. La sobreposición de estos mapas de distribución permitió la identificación de la subregión más rica en aves amenazadas,los bosques en bajíos del Estado de Río de Janeiro. Dimos relevancia a ocho fragmentos prioritarios, con atención en uno con imágenes de resolución fina para estudio en detalle. Este método permite la priorización de áreas para conservación de fragmentos de decenas de kilómetros cuadrados en una región >1 millón km2. La información biológica general es suficiente para definir prioridades de conservación de la biodiversidad. Por lo tanto, nuestro método es atractivo para localidades tropicales y biológicamente ricas, para las que la información sobre la ocalización de las especies es escasa. [source]

Factors influencing the spatial distribution of zooplankton and fish in Loch Ness, UK

FRESHWATER BIOLOGY, Issue 4 2000
D. G. George
Summary 1The vertical and horizontal distribution of phytoplankton, zooplankton and fish in Loch Ness, Scotland, were monitored during one day-time and one night-time survey in July 1992. The vertical samples were collected at a site located at the northern end of the loch and the horizontal samples along a longitudinal transect. 2The vertical distribution surveys demonstrated that the phytoplankton, the zooplankton and the fish were concentrated in the top 30 m of water above the seasonal thermocline. Within this layer, Cyclops stayed much closer to the surface than Eudiaptomus but both species moved towards the surface at night. 3The most important factor influencing the horizontal distribution of the phytoplankton was the north- south gradient in productivity. The sub-catchments surrounding the north basin contain a greater proportion of arable land than those to the south and the concentrations of nitrate-nitrogen and phytoplankton chlorophyll increased systematically from south to north. 4Zooplankton distribution patterns were influenced by wind-induced water movements and the dispersion of allochthonous material from the main inflows. The highest concentrations of Cyclops were recorded in the north, where there was more phytoplankton, and the highest concentrations of Eudiaptomus in the south, where there were higher concentrations of non-algal particulates. 5There was no spatial correlation between total zooplankton and total fish abundance but the highest concentrations of small (1,5 cm) fish were recorded in the south where there was a large patch of Eudiaptomus. The number of Eudiaptomus at specific locations within this patch were, however, negatively correlated with the numbers of small fish. These results suggest that the fish were actively foraging within the patch and were depleting their zooplankton prey in the areas where they were most abundant. [source]

Severe Deep Moist Convective Storms: Forecasting and Mitigation

GEOGRAPHY COMPASS (ELECTRONIC), Issue 1 2008
David L. Arnold
Small-scale (2,20 km) circulations, termed ,severe deep moist convective storms', account for a disproportionate share of the world's insured weather-related losses. Spatial frequency maximums of severe convective events occur in South Africa, India, Mexico, the Caucasus, and Great Plains/Prairies region of North America, where the maximum tornado frequency occurs east of the Rocky Mountains. Interest in forecasting severe deep moist convective systems, especially those that produce tornadoes, dates to 1884 when tornado alerts were first provided in the central United States. Modern thunderstorm and tornado forecasting relies on technology and theory, but in the post-World War II era interest in forecasting has also been driven by public pressure. The forecasting process begins with a diagnostic analysis, in which the forecaster considers the potential of the atmospheric environment to produce severe convective storms (which requires knowledge of the evolving kinematic and thermodynamic fields, and the character of the land surface over which the storms will pass), and the likely character of the storms that may develop. Improvements in forecasting will likely depend on technological advancements, such as the development of phased-array radar systems and finer resolution numerical weather prediction models. Once initiated, the evolution of deep convective storms is monitored by satellite and radar. Mitigation of the hazards posed by severe deep moist convective storms is a three-step process, involving preparedness, response, and recovery. Preparedness implies that risks have been identified and organizations and individuals are familiar with a response plan. Response necessitates that potential events are identified before they occur and the developing threat is communicated to the public. Recovery is a function of the awareness of local, regional, and even national governments to the character and magnitude of potential events in specific locations, and whether or not long-term operational plans are in place at the time of disasters. [source]

Detection and quantification of flaws in structures by the extended finite element method and genetic algorithms

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2010
Haim Waisman
Abstract This paper investigates the extended finite element method (XFEM)-GA detection algorithm proposed by Rabinovich et al. (Int. J. Numer. Meth. Engng 2007; 71(9):1051,1080; Int. J. Numer. Meth. Engng 2009; 77(3):337,359) on elastostatic problems with different types of flaws. This algorithm is designed for non-destructive assessment of structural components. Trial flaws are modeled using the XFEM as the forward problem and genetic algorithms (GAs) are employed as the optimization method to converge to the true flaw location and size. The main advantage of the approach is that XFEM alleviates the need for re-meshing the domain at every new iteration of the inverse solution process and GAs have proven to be robust and efficient optimization techniques in particular for this type of problems. In this paper the XFEM-GA methodology is applied to elastostatic problems where flaws are considered as straight cracks, circular holes and non-regular-shaped holes. Measurements are obtained from strain sensors that are attached to the surface of the structure at specific locations and provide the target solution to the GA. The results show convergence robustness and accuracy provided that a sufficient number of sensors are employed and sufficiently large flaws are considered. Copyright © 2009 John Wiley & Sons, Ltd. [source]

A new methodology for the determination of the co-ordination area around stations of the fixed service (FS) with respect to mobile Earth stations on board vessels (ESVs)

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2005
Maria Koletta
Abstract The extensive use of Earth stations located on board sea going vessels (ESVs) has created the necessity for the development of a new type of co-ordination area around the fixed service receivers (FSRs) operating in frequency bands C and Ku. To date there is not a single method concerning the calculation of the co-ordination area around the FSRs, which takes into account the mobility of the interfering stations. This paper addresses an in-depth analysis of the interference produced to the FSRs by the ESVs and proposes a new method for the development of the co-ordination area around the FSRs, taking into account parameters such as the velocity of the ESVs and their frequencies of passage from specific locations. Simulations performed for three different operational scenarios prove the validity of the new methodology. Copyright © 2005 John Wiley & Sons, Ltd. [source]

More Difficult to Believe?

INTERNATIONAL JOURNAL OF SYSTEMATIC THEOLOGY, Issue 1 2001
Luther on Divine Omnipotence
This article considers Luther's statement in thesis 21 of the 1545 doctoral disputation of Petrus Hegemon (1545) concerning the difficulty of belief in creatio ex nihilo, and suggests that this difficulty shapes the later Luther's theology in significant ways. The difficulty is reconstructed as a gradual movement into the mystery of the creatio ex nihilo. The first site of difficulty correlates the knowledge of creatures as particulars with the knowledge of the Creator as the source of existence. The move towards a second site is propelled by the question of inevitable death, which Luther answers by moving from material and natural generation to the resurrection and then to the creatio ex nihilo. At the third site, Luther addresses such disturbing questions as the suffering of the righteous, the historical cycle of political power, and the harshness of reprobation. He answers these questions by integrating the symmetrical biblical statements of the annihilatio and the creatio with a theological theory of divine omnipotence. God's hiddenness is understood as God's omnipotence working at the specific locations of self-negation, as well as behind the ebb and flow of historical-political contingency. Faith presses into the hidden mystery, grounded in the certainty that all things are effected by the Creator whose nature is self-giving goodness, and established by the hope that the light of glory will determine more fully the God who is to be honored above all. [source]

Think Locally, Act Globally: Toward a Transnational Comparative Politics,

INTERNATIONAL POLITICAL SOCIOLOGY, Issue 2 2010
Terrence Lyons
Political dynamics and outcomes around the globe have been transformed by globalization, new patterns of human mobility, and the development of innovative transnational social networks. These new political processes are rooted in communities and networks that are not restricted by geographic location. Although politics has been delinked from territory in this way with regard to processes and actors, this does not mean that transnational politics focuses exclusively on universal issues or global approaches to social justice. Rather much of the new transnational politics is intensely focused on specific locations, identities, and issues (for example, "globalized" neighborhood associations, ethnicities, patrimonialism). Transnational politics also includes new conceptions and practices of citizenship and accountability (for example, legislative seats reserved for expatriate labor migrants) as the body politic becomes increasing mobile, political affinities delinked from geographic proximity, and critical constituencies reside outside of the territory of the state. This article outlines a new approach to investigating the actors and processes at the heart of contemporary transnational politics, with a particular focus on the ways in which diasporas are strategically constructed and mobilized to advance political goals through the use of salient symbols, identity frames, and social networks. [source]

Risk modelling in blood safety , review of methods, strengths and limitations

ISBT SCIENCE SERIES: THE INTERNATIONAL JOURNAL OF INTRACELLULAR TRANSPORT, Issue n1 2010
B. Custer
Risk modelling studies in blood safety play an important but occasionally misunderstood role. These studies are intended to quantify and contrast risks and benefits. This information is critical for policy development and intervention decision-making. The limitations of risk modelling should be considered alongside the results obtained. The goal of this manuscript and presentation is to review current risk modelling techniques used in blood safety and to discuss the pros and cons of using this information in the decision-making process. The types of questions that can be answered include the extent of a risk or threat; implications of action or inaction; identification of effective strategies for risk management; or whether to adopt specific interventions. These analyses can be focused on a risk alone but are often combined with economic information to gain an understanding of feasible risk interventions given budgetary or other monetary considerations. Thus, analyses that include risk modelling provide insights along multiple lines. As important, the analyses also provide information on what is not known or uncertain about a potential hazard and how much that uncertainty may influence the decision-making process. Specific examples of the range of risk analyses in which the author has participated will be reviewed and will include ongoing process improvement in testing laboratories such as error identification/eradication, estimation of the risk of malaria exposure based on the specific locations of travel, evaluation of blood supply and demand during an influenza pandemic, cost-utility analyses of screening interventions for infectious diseases in countries with different human development indices, and insurance against emerging pathogen risk. Each of these analyses has a different purpose and seeks to answer different questions, but all rely on similar methods. The tool kit for risk analysis is broad and varied but does have limitations. The chief limitation of risk modelling is that risk analyses are not scientific experiments or otherwise controlled studies. Consequently, the analyses are more apt to be influenced by assumptions. These assumptions may be necessary to structure a problem in a way that will allow the question of interest to be answered or may result from incomplete or missing information. Another potential limitation is that commissioners of such studies, those who undertake them, and the intended audience, such as regulatory agencies, may have distinct and differing interpretations of the results. Risk modelling is a set of techniques that can be used to inform and support decision-making at all levels in transfusion medicine. Advances in risk modelling techniques allow for continued expansion in the scope of possible questions that can be analysed. Expanded use also improves the acceptance of the utility of these studies in blood safety and transfusion medicine. [source]

Structural Trends in the Aging Femoral Neck and Proximal Shaft: Analysis of the Third National Health and Nutrition Examination Survey Dual-Energy X-Ray Absorptiometry Data,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 12 2000
Thomas J. Beck
Abstract Hip scans of U.S. adults aged 20,99 years acquired in the Third National Health and Nutrition Examination Survey (NHANES III) using dual-energy X-ray absorptiometry (DXA) were analyzed with a structural analysis program. The program analyzes narrow (3 mm wide) regions at specific locations across the proximal femur to measure bone mineral density (BMD) as well as cross-sectional areas (CSAs), cross-sectional moments of inertia (CSMI), section moduli, subperiosteal widths, and estimated mean cortical thickness. Measurements are reported here on a non-Hispanic white subgroup of 2719 men and 2904 women for a cortical region across the proximal shaft 2 cm distal to the lesser trochanter and a mixed cortical/trabecular region across the narrowest point of the femoral neck. Apparent age trends in BMD and section modulus were studied for both regions by sex after correction for body weight. The BMD decline with age in the narrow neck was similar to that seen in the Hologic neck region; BMD in the shaft also declined, although at a slower rate. A different pattern was seen for section modulus; furthermore, this pattern depended on sex. Specifically, the section modulus at both the narrow neck and the shaft regions remains nearly constant until the fifth decade in females and then declined at a slower rate than BMD. In males, the narrow neck section modulus declined modestly until the fifth decade and then remained nearly constant whereas the shaft section modulus was static until the fifth decade and then increased steadily. The apparent mechanism for the discord between BMD and section modulus is a linear expansion in subperiosteal diameter in both sexes and in both regions, which tends to mechanically offset net loss of medullary bone mass. These results suggest that aging loss of bone mass in the hip does not necessarily mean reduced mechanical strength. Femoral neck section moduli in the elderly are on the average within 14% of young values in females and within 6% in males. [source]

WATERSHED SCALE INVENTORY OF EXISTING RIPARIAN BUFFERS IN NORTHEAST MISSOURI USING GIS,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2006
Joseph P. Herring
ABSTRACT: An observational study was conducted at the watershed scale using land cover (vegetation) data to assess the absence or presence of riparian buffers in three northeastern Missouri watersheds. Forests and grasslands lying within a 61 m (200 ft) parallel band directly adjacent to streams were considered "buffers" for improving or protecting water quality and were characterized according to their length, width, and vegetation type. Results indicated that riparian buffers were abundant throughout the watersheds but were typically narrow along first-order and second-order streams; in many cases they may not have been wide enough to provide adequate stream protection. At least 90 percent of all streams had buffer vegetation immediately adjacent to the streambanks, but as few as 31 percent of first-order streams had buffers extending to 61 m from the stream on at least one side. On-site evaluations are needed to determine the condition of these forests and grasslands and their ability to process nonpoint source pollutants. The results will be useful for providing natural resource managers with knowledge of current watershed conditions as well as in identifying specific locations for future conservation efforts within each watershed. [source]

MODELING METALS TRANSPORT AND SEDIMENT/WATER INTERACTIONS IN A MINING IMPACTED MOUNTAIN STREAM,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2004
Brian S. Caruso
ABSTRACT: The U.S. Environmental Protection Agency (USEPA) Water Quality Analysis Simulation Program (WASP5) was used to model the transport and sediment/water interactions of metals under low flow, steady state conditions in Tenmile Creek, a mountain stream supplying drinking water to the City of Helena, Montana, impacted by numerous abandoned hard rock mines. The model was calibrated for base flow using data collected by USEPA and validated using data from the U.S. Geological Survey (USGS) for higher flows. It was used to assess metals loadings and losses, exceedances of Montana State water quality standards, metals interactions in stream water and bed sediment, uncertainty in fate and transport processes and model parameters, and effectiveness of remedial alternatives that include leaving contaminated sediment in the stream. Results indicated that during base flow, adits and point sources contribute significant metals loadings to the stream, but that shallow ground water and bed sediment also contribute metals in some key locations. Losses from the water column occur in some areas, primarily due to adsorption and precipitation onto bed sediments. Some uncertainty exists in the metal partition coefficients associated with sediment, significance of precipitation reactions, and in the specific locations of unidentified sources and losses of metals. Standards exceedances are widespread throughout the stream, but the model showed that remediation of point sources and mine waste near water courses can help improve water quality. Model results also indicate, however, that alteration of the water supply scheme and increasing base flow will probably be required to meet all water quality standards. [source]

Post-fire tree establishment patterns at the alpine treeline ecotone: Mount Rainier National Park, Washington, USA

JOURNAL OF VEGETATION SCIENCE, Issue 1 2009
Kirk M. Stueve
Abstract Questions: Does tree establishment: (1) occur at a treeline depressed by fire, (2) cause the forest line to ascend upslope, and/or (3) alter landscape heterogeneity? (4) What abiotic and biotic local site conditions are most important in structuring establishment patterns? (5) Does the abiotic setting become more important with increasing upslope distance from the forest line? Location: Western slopes of Mount Rainier, USA. Methods: We performed classification analysis of 1970 satellite imagery and 2003 aerial photography to delineate establishment. Local site conditions were calculated from a LIDAR-based DEM, ancillary climate data, and 1970 tree locations in a GIS. We used logistic regression on a spatially weighted landscape matrix to rank variables. Results: Considerable establishment after 1970 caused forest line elevation to increase over 150 m in specific locations. Landscape heterogeneity increased with distance from the 1970 forest line. At a broad spatial context, we found establishment was most common near existing trees (0-50 m) and at low elevations (1250-1350 m). Slope aspect (W, NW, N, NE, and E), slope angle (40-60°), and other abiotic factors emerged as important predictors of establishment with increasing upslope distance from the forest line to restricted spatial extents. Conclusions: Favorable climatic conditions likely triggered widespread tree establishment. Readily available seed probably enhanced establishment rates near sexually mature trees, particularly in the less stressful environment at low elevations. The mass effect of nearly ubiquitous establishment in these areas may have obscured the importance of the abiotic setting to restricted spatial extents. Topographic variability apparently produced favorable sites that facilitated opportunistic establishment with increasing upslope distance from the forest line, thereby enabling additional trees to invade the alpine tundra. [source]

Vegetation, environment, and time: The origination and termination of ecosystems

JOURNAL OF VEGETATION SCIENCE, Issue 5 2006
Stephen T. Jackson
Abstract Terrestrial ecosystems originate when particular plant species attain dominance at specific locations under specific environmental regimes. Ecosystems terminate, gradually or abruptly, when the dominant species or functional types are replaced by others, usually owing to environmental change or severe and irreversible disturbance. Assessing whether current ecosystems are sustainable in the face of future environmental change can be aided by examining the range of environmental variation those ecosystems have experienced in the past, and by determining the environmental conditions under which those ecosystems arose. The range of environmental variation depends on the time scale at which it is assessed. A narrow time span (e.g. 200,300 years) may underestimate the range of variation within which an ecosystem is sustainable, and it may also underestimate the risk of major transformation or disruption of that ecosystem by environmental change. Longer time spans (e.g. 1000,2000 years) increase the range of variation, by encompassing a larger sample of natural variability as well as non-stationary variability in the earth system. Most modern ecosystems disappear when the time span is expanded to 10000,15 000 years owing to secular changes in earth's climate system. Paleo-ecological records can pinpoint the time of origination of specific ecosystems, and paleo-environmental records can reveal the specific environmental changes that led to development of those ecosystems and the range of environmental variation under which those ecosystems have maintained themselves in the past. This information can help identify critical environmental thresholds beyond which specific modern ecosystems can no longer be sustained. [source]

Review of Pododermatitis Circumscripta (Ulceration of the Sole) in Dairy Cows

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 4 2006
Sarel R. van Amstel
Sole ulcers are among the most frequent causes of lameness in dairy cattle. They are found most commonly in the hind lateral claw, are frequently bilateral, and have a high rate of reoccurrence. The pathogenesis of sole ulceration is primarily based on mechanical injury by the 3rd phalanx to the corium, basement membrane, and basal layers of the sole epidermis as a result of failure of the suspensory apparatus in the claw. The main pathways in the failure of the suspensory system include inflammatory (dermal vascular changes followed by disruption of keratinocyte proliferation and differentiation caused by local and systemic mediators) and noninflammatory (hormonal and biochemical changes in the peripartum period resulting in alterations of connective tissue in the suspensory system) pathways. Sole ulcers tend to occur in specific locations; the most reported site is the junction of the axial heel and sole. Other locations include the apex of the toe and the heel. Varying degrees of lameness may result, and the most severe are seen with complicated cases in which ascending infection affects the deeper structures of the claw. Pathologic changes at the ulcer site include dyskeratosis and dilated horn tubules with microcracks. Vascular changes include dilatation and thrombosis of capillaries with "neocapillary formation." Areas of dyskeratosis may remain for as long as 50 days at the ulcer site. Treatment includes corrective trimming and relief of weight bearing. Complicated cases may require surgical intervention. [source]

3D Pharmacophore Model for Insect Repellent Activity and Discovery of New Repellent Candidates

MOLECULAR INFORMATICS, Issue 5 2005
Apurba
Abstract To better understand the mechanism of insect repellency and to identify new repellent candidates, we performed a three-dimensional quantitative structure-activity (QSAR) study and developed a pharmacophore model for potent repellent activity from a set of eleven known diverse insect repellent compounds by using the CATALYST 3D-QSAR methodology. The protection time for repellent activity of the compounds was taken from an earlier published study. The pharmacophore was found to have three hydrophobic sites (two aliphatic and one aromatic) and a hydrogen-bond acceptor site in specific locations in the three dimensional geometry of the molecules that are critical for potent repellent activity. The pharmacophore showed an excellent correlation (correlation=0.9) between the experimental protection time afforded by the compounds in the training set and their predicted protection time. The validity of the pharmacophore model goes beyond the list in the training set and is found to map well on a variety of other insect repellents. By mapping this model on one of the more potent analogue we have generated a three-dimensional shape based template which allowed a search of our in-house compound database and discover four new potential insect repellent candidates. [source]

Individual chitin synthase enzymes synthesize microfibrils of differing structure at specific locations in the Candida albicans cell wall

MOLECULAR MICROBIOLOGY, Issue 5 2007
Megan D. Lenardon
Summary The shape and integrity of fungal cells is dependent on the skeletal polysaccharides in their cell walls of which ,(1,3)-glucan and chitin are of principle importance. The human pathogenic fungus Candida albicans has four genes, CHS1, CHS2, CHS3 and CHS8, which encode chitin synthase isoenzymes with different biochemical properties and physiological functions. Analysis of the morphology of chitin in cell wall ghosts revealed two distinct forms of chitin microfibrils: short microcrystalline rodlets that comprised the bulk of the cell wall; and a network of longer interlaced microfibrils in the bud scars and primary septa. Analysis of chitin ghosts of chs mutant strains by shadow-cast transmission electron microscopy showed that the long-chitin microfibrils were absent in chs8 mutants and the short-chitin rodlets were absent in chs3 mutants. The inferred site of chitin microfibril synthesis of these Chs enzymes was corroborated by their localization determined in Chsp,YFP-expressing strains. These results suggest that Chs8p synthesizes the long-chitin microfibrils, and Chs3p synthesizes the short-chitin rodlets at the same cellular location. Therefore the architecture of the chitin skeleton of C. albicans is shaped by the action of more than one chitin synthase at the site of cell wall synthesis. [source]

Gabbroic clay sources in Cornwall: a petrographic study of prehistoric pottery and clay samples

OXFORD JOURNAL OF ARCHAEOLOGY, Issue 3 2004
Lucy Harrad
Summary., This analysis of prehistoric pottery and clay samples from Cornwall demonstrates that the clay used to make Cornish gabbroic pottery in prehistory originated around the gabbro rock outcrop in a small area of the Lizard peninsula. The research uses petrographic and chemical analysis to subdivide the prehistoric pottery into six groups. Owing to the unusual geology of the Lizard these groups can be attributed to specific locations. The most abundant pottery fabric, Typical Gabbroic, was made using coarse clay which is mainly found in a 1 km2 area near Zoar. A finer version of this clay, found higher in the soil profile or slightly transported and redeposited, was used to make Fine Gabbroic pottery and an even finer variant called FNS (Fine Non-Sandy) Gabbroic. We identify for the first time here a Loessic/Gabbroic pottery fabric which can be matched exactly to clay found at Lowland Point. Serpentinitic/Gabbroic pottery was made using clay from the gabbro/serpentinite border zone. Pottery made from the Granitic/Gabbroic fabric did not match any clay from the Lizard, showing that gabbroic clay was sometimes removed and made into pottery elsewhere in Cornwall. The main clay source near Zoar was used for clay extraction throughout the Bronze Age and Iron Age for pottery which was traded all over Cornwall. Other gabbroic clay sources produced pottery only during certain periods and exclusively supplied particular settlements, such as the Loessic/Gabbroic fabric which was found only at Gear and Caer Vallack. The results suggest that pottery was produced by several small-scale cottage industries, which may have operated on a seasonal, part-time basis and probably formed only part of a wide range of activities located around the Lizard area. [source]

Effect of glass bead content and diameter on shrinkage and warpage of injection-molded PA6

POLYMER ENGINEERING & SCIENCE, Issue 11 2009
J.G. Kovács
A simple technique has been introduced to evaluate the shrinkage and warpage behavior of injection molded products. Using the shrinkage values measured on specific locations of the specimen, three deformation factors have been defined to characterize the warpage behavior of the materials examined. Experiments were carried out to determine these properties of injection molded polyamide 6 (PA6) composites with solid glass bead (GB) contents of 10, 20, 30, 40 wt% and diameters of 11, 85, 156, 203 ,m. It was concluded that the flow directional shrinkages can principally be described by the change in the bead content and diameter; it was proven that the increase in bead content and in bead diameter induces a reduction in flow directional shrinkage. The rising bead content and diameter increased the deformation factor, defined by the shrinkage differences caused by the pressure drop. It was pointed out that the ideal bead content can be determined in the function of bead diameter. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source]

Genotyping single nucleotide polymorphisms using intact polymerase chain reaction products by electrospray quadrupole mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2001
James J. Walters
Both single nucleotide polymorphisms (SNPs) and mutations are commonly observed in the gene encoding the tumor suppressor protein, p53. SNPs occur at specific locations within genes whereas mutations may be distributed across large regions of genes. When determining nucleotide differences, mass spectrometry is the only method other than Sanger sequencing which offers direct structural information. Electrospray ionization (ESI) quadrupole mass spectrometry (MS) analysis of intact polymerase chain reaction (PCR) products was performed following a simple purification and on-line heating to limit ion adduction. The PCR products were amplified directly from genomic DNA rather than plasmids, as in our previous work. Two known polymorphisms of the p53 gene were genotyped. A cytosine (C) or guanine (G) transversion, designated C,,,G (G,,,C on the opposite strand), were each detected by a 40.0,Da change upon ESI quadrupole MS analysis. Using known PCR products as standards, the genotypes determined for 10 human samples corresponded with restriction fragment length polymorphism (RFLP) analysis. Cytosine/thymine (T) transitions, designated C,,,T (G,,,A on the opposite strand), were also genotyped by ESI-MS. This SNP is discriminated by a 15.0,Da change on one strand (C,,,T) and a 16.0,Da change on the other (G,,,A). Appropriate sample preparation and instrumental configuration (including heated sample inlet syringe and MS source), to limit adducts, are both vital for successful ESI quadrupole MS analysis of intact PCR products. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Working memory for ballet moves and spatial locations in professional ballet dancers

APPLIED COGNITIVE PSYCHOLOGY, Issue 2 2010
Antonio Cortese
The aim of the present study was to investigate working memory for ballet moves in expert dancers. Experiment 1 showed that a concurrent spatial task did not interfere with the recall of a sequence of ballet moves when these were encoded alone without being associated with spatial locations. Experiment 2 showed that a concurrent motor task selectively interfered with the recall of ballet moves while neither a concurrent motor task nor a spatial task affected recall of the specific locations where each ballet move had to be performed. Experiment 3 showed that spatial interference affected recall of sequences of locations when these were encoded alone. Finally, in Experiment 4, a similarity effect for patterned ballet movements was shown. Taken together results show that spatial interference does not affect short-term memory for ballet moves thus suggesting that working memory might contain a system for motor configurations. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Experimentelle Bestimmung der hygrischen Sorptionsisotherme und des Feuchtetransportes unter instationären Bedingungen

BAUPHYSIK, Issue 2 2006
Assistent und Laborleiter Rudolf Plagge Dr.-Ing.
Mit der vorgestellten Augenblicksprofil-Methode (APM) werden sowohl die relative Luftfeuchte und die Temperatur, als auch der volumetrische Wassergehalt in bestimmten Positionen in einem porösen Material bestimmt. Die Messungen werden kontinuierlich unter instationären Bedingungen durchgeführt. Damit erlaubt die APM eine dynamische und gleichzeitige Messung der hygroskopischen Sorptionsisotherme und der hygrischen Feuchteleitfähigkeit für einzelne Kompartimente innerhalb der Materialprobe. Die Feuchteleitfähigkeit wird aus den sich zeitlich ändernden Potentialgradienten und den dazugehörigen Feuchteverteilungen für die jeweiligen Kompartimente berechnet. Die Anwendung nicht konstanter Randbedingungen in der APM erlaubt die Untersuchung des hygrodynamischen Verhaltes von porösen Materialien. In der vorliegenden Studie werden die zeit- und prozeßabhängige Feuchtespeicherung und der Feuchtetransport bestimmt. Die vorgestellten Adsorptions- und Desorptionsexperimente wurden an dem kapillar- aktiven Wärmedämmstoff Calciumsilikat durchgeführt. Die Ergebnisse geben das Hystereseverhalten und den Einfluß der Dynamik der Prozesse wider. In Positionen mit schnellen Feuchteänderungen wird die Feuchtespeicherfunktion im Vergleich mit Regionen langsamer Feuchteänderung nach oben verschoben. Die Feuchteleitfähigkeit als Funktion der relativen Luftfeuchte zeigt eine bedeutende Hysterese. Hingegen ist die Feuchteleitfähigkeit in Relation zum Wassergehalt nicht hysteretisch. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Experimental determination of the hygroscopie sorption isotherm and the moisture conductvity under transient conditions. By means of the proposed Instantaneous Profile Method (IPM) the relative humidity or the capillary pressure as well as the volumetric water content at specific locations inside a porous medium can be determined. The measurements are carried out under transient conditions and continuously in time. Thus, the IPM allows dynamic measurements of the hygroscopic sorption isotherm and the hygroscopic moisture conductivity. In addition, the moisture conductivity can be obtained via calculation of the moisture flow distribution from the temporal change of moisture contents in the compartments of the sample. The application of non-constant boundary conditions in the IPM allows investigation of the hygrodynamic behaviour of porous materials. In the presented study, the time and process dependent moisture retention characteristic and moisture conductivity are determined. The adsorption and successive desorption experiments presented here have been performed on the capillary active insulation material Calcium Silicate. The results show a hysteretic behaviour with a pregnant influence of the process dynamics. At locations with a rapid moisture increase, the moisture retention characteristic is shifted up in comparison to regions with slow moisture change. The moisture conductivity as function of relative humidity shows a remarkable hysteresis. However, the moisture conductivity in relation to the water content turned out to be non-hysteretic. [source]

Plasticity, its cost, and phenotypic selection under water and nutrient stress in two annual grasses

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2009
SERGEI VOLIS
A comparative approach can prove to be a useful tool for studying phenotypic plasticity, if applied to specific traits involved in adaptation to particular environment in more than one species across co-located populations. The present study tested whether two annual grasses, Hordeum spontaneum and Avena sterilis, belonging to the same guild, having similar stature, seed dispersal mechanism, breeding system, and genetic variation, and sampled in exactly the same environmentally specific locations, differed with respect to: (1) plasticity in traits involved in adaptation, namely the onset of reproduction and maternal investment involving the number of inflorescences, spikelets per inflorescence, the weight of individual spikelets, and abortion rate; (2) the cost of this plasticity, and (3) the pattern of phenotypic selection on the above traits. The two species exhibited highly differing amounts of phenotypic plasticity in the onset of flowering and several reproductive traits (number of inflorescences, spikelets per inflorescence, abortion rate), but no plasticity costs in any experimental environment. The two species demonstrated a decreasing similarity in the regulation of reproduction in four experimental environments: benign, water, nutrients and water × nutrient deficient. Correlational selection appears to contribute, although not solely, to the observed species differences with respect to the regulation of reproduction. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 581,593. [source]

Regional Climate Change: Trend Analysis of Temperature and Precipitation Series at Selected Canadian Sites

CANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 1 2000
J. Stephen Clark
Global climate change does not necessarily imply that temperature or precipitation is increasing at specific locations. The hypothesis of increasing temperature and precipitation trends associated with global climate change is tested using actual annual temperature and precipitation data for nine selected weather stations, spatially distributed across Canada. Vogelsang's (1998) partial sum and Woodward et al's (1997) bootstrap methods are used for testing for trend. Both methods suggest no warming in the Canadian temperature series except for Toronto, Ontario, which had significant increase over time, along with Moncton, New Brunswick, and Indian Head, Saskatchewan, which had marginal increases. There is no evidence of increasing trend in precipitation except for Moncton, New Brunswick, which had a significantly increasing trend. Thus, public policies designed to address the regional effects of climate change need to be adapted for a particular ecological zone, based on knowledge of the climate trends for that region, rather than on general global climate change patterns. Les changements climatiques ŕ l'échelle planétaire ne signifient pas nécessairement que la température et les précipitations sont en augmentation dans des emplacements donnés. Nous avons testé I'hypothčse d'une assoviation de la tendance ŕ la hausse de la température et des précipitations avec les changements climatiques planétaires ŕ partir des données réelles de température et de précipitations obtenues ŕ 9 stations d'observation climatique réparties dans les diverses régions du Canada. Nous utilisons, pour cefaire, la méthode des sommes partielles de Vogelsang (1998) et celle de rééchantillonnage bootstrap de Woodward et al (1997). Les deux méthodes ne révčlent aucun réchauffement de la température dans les séries chronologiques, sauf pour Toronto, en Ontario, oů l'on constate une hausse significative en fonction du temps, ainsi que pour Moncton au Nouveau-Brunswick et Indian Head en Saskatchewan qui marquent de trčs légčres augmentations. Rien n'indique une tendance ŕ la hausse des précipitations, sauf ŕ Moncton oů se dessine une tendance significative dans ce sens. Les programmes publics destinés ŕ faire face aux effets régionaux du changement climatique doivent donc ętre adaptés ŕ chaque zone écologique particuličre, ŕ partir d"observations faites dans la région męme, plutôt que de la configuration du changement climatique ŕ l'échelle planétaire. [source]