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Primary Importance (primary + importance)
Selected AbstractsEffect of phosphonate additive on crystallization of gypsum in phosphoric and sulfuric acid mediumCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2002H. El-Shall Abstract Understanding the mechanisms of growth and inhibition during crystallization of calcium sulfate is of primary importance for many industrial applications. For instance, inhibition of the crystallization process may be required to prevent scale formation in pipes, boilers, heat exchangers, reactors, reverse osmosis membrane surfaces, cooling water systems, secondary oil recovery utilizing water flooding techniques and desalination evaporators, etc. On the other hand, control growth and morphology of gypsum crystals is desired in achieving higher filtration rate and higher productivity of phosphoric acid from phosphate rocks. In this regard, this basic study is carried out to understand effect of Aminotris (methylenephosphonic acid (ATMP) on calcium sulfate dihydrate (gypsum) crystallization. The time elapsed between the achievement of supersaturation and the appearance of a solid phase (termed as induction time) is measured under different supersaturation ratios ranging from 1.018 to 1.979. The data are used to calculate the surface energy, critical nucleus size, and crystal growth rates of gypsum under different conditions. The results show that, the induction time decreases exponentially with increasing the supersaturation ratio. In addition, the surface energy decreases with ATMP compared to the baseline (without ATMP). Interestingly, with addition of the ATMP, the crystals mean and median diameters are found to decrease. The inhibition efficiency ranges from 16% to 59% depending on supersaturation ratio. [source] Development of an inhibitory antibody fragment to human tissue factor using phage display technologyDRUG DEVELOPMENT RESEARCH, Issue 3 2009S.M. Meiring Abstract Tissue factor is involved in the etiology of thrombotic diseases initiating the thrombosis associated with the inflammation that occurs during infection. The prevention of blood coagulation and inflammation is of primary importance in a number of pathological situations. A single-chain variable antibody fragment of molecular weight of 26,kD that inhibits the action of human tissue factor was selected by phage display technology, purified and tested for its tissue factor inhibitory effect, purified on a protein A column, and its purity evaluated on SDS-PAGE. The effects of the antibody fragment on prothrombin times, Factor Xa production, and thrombin generation were assessed with increasing fragment concentrations, using chromogenic and fluorometric substrates. The antibody fragment dose-dependently prolonged the prothrombin time (IC50=0.5,,M) and delayed the lag phase before the thrombin generation burst and the peak thrombin concentration in the thrombin generation assay. The effect on thrombin generation was more pronounced in thrombophilic plasma than in normal plasma. Antibody-based tissue factor inhibitors therefore may provide an effective treatment for thrombotic disease without serious bleeding complications. Drug Dev Res 2009. © 2009 Wiley-Liss, Inc. [source] The spatial distribution of badgers, setts and latrines: the risk for intra-specific and badger-livestock disease transmissionECOGRAPHY, Issue 4 2008Monika Böhm The spatial distribution of wildlife hosts and the associated environmental distribution of their excretory products are important factors associated with the risk of disease transmission between wildlife and livestock. At a landscape scale, heterogeneous distribution of a wildlife host will create regional hot spots for disease risk, while at the farm level, distributional patterns of wildlife excretory products as well as habitat use are of primary importance to the assessment of disease risk to livestock. In the UK, badgers have been implicated in the transmission of bovine tuberculosis to cattle. In this study, we focus on the spatial and social organization and habitat use of badgers as well as the distributions of their excretions at latrine and sett sites to assess intra- and inter-species (badger,cattle) disease risk. Across the study site, badger latrines and setts were found in prominent clusters, at distances of up to 250 and 200 m respectively. This was partly due to small-scale clustering of latrines around sett sites, so that disease risk may be higher within the vicinity of setts. The clustered distribution suggests that sites of high risk for TB transmission may be localised within farms. Exclusion of cattle from the few sett and latrine sites within their grazing pasture is therefore likely to provide an effective way of reducing the risk of disease transmission. We also found evidence of social sub-division within badger social groups based on differences in the use of main and outlier setts. This may contribute to localised clusters of infection within the badger population, resulting in heterogeneous patterns of environmental disease risk to the wider host community. A greater understanding of variation in host behaviour and its implications for patterns of disease will allow the development of more targeted and effective management strategies for wildlife disease in group-living hosts. [source] The relative importance of landscape and community features in the invasion of an exotic shrub in a fragmented landscapeECOGRAPHY, Issue 2 2006Anne M. Bartuszevige Although invasive plants are recognized as a major ecological problem, little is known of the relative importance of plant community characteristics versus landscape context in determining invasibility of communities. We determined the relative importance of community and landscape features of 30 woodlots in influencing the invasion of Lonicera maackii. We sampled woodlots using the point-quarter method and calculated canopy openness and basal areas and densities of shrub, sapling and tree species, as well as woody species richness. We used aerial photos and ArcView GIS to calculate landscape parameters from the same woodlots using a buffer distance of 1500,m. We used logistic and linear regression analyses to determine the community and landscape factors that best explain L. maackii presence and density. We also tested whether woodlot invasion by L. maackii begins at woodlot edges. Presence of L. maackii was significantly explained only by distance from the nearest town (logistic regression, p=0.017); woodlots nearer town were more likely to be invaded. Among invaded woodlots, density of L. maackii was positively related to the amount of edge in the landscape (partial R2=0.592) and negatively related to total tree basal area (partial R2=0.134), number of native woody species (partial R2=0.054), and sapling shade tolerance index (partial R2=0.054). Lonicera maackii in woodlot interiors were not younger than those on the perimeters, leading us to reject the edge-first colonization model of invasion. Our findings reveal that landscape structure is of primary importance and community features of secondary importance in the invasion of L. maackii. This shrub is invading from multiple foci (towns) rather than an advancing front. Connectivity in the landscape (i.e. the number of corridors) did not promote invasion. However, edge habitat was important for invasion, probably due to increased propagule pressure. The community features associated with L. maackii invasion may be indicators of past disturbance. [source] Ds -optimal designs for studying combinations of chemicals using multiple fixed-ratio ray experimentsENVIRONMETRICS, Issue 2 2005Michelle Casey Abstract Detecting and characterizing interactions among chemicals is an important environmental issue. Traditional factorial designs become infeasible as the number of compounds under study increases. Ray designs, which reduce the amount of experimental effort, can be considered when interest is restricted to relevant mixing ratios. Simultaneous tests for departure from additivity across multiple fixed-ratio rays in the presence and absence of single chemical data have been developed. Tests for characterizing interactions among subsets of chemicals at relevant mixing ratios have also been developed. Of primary importance are precise estimates for the parameters associated with these hypotheses. Since the hypotheses of interest are stated in terms of subsets of parameters, we have developed a methodology for finding Ds -optimal designs, which are associated with the minimum generalized variance of subsets of the parameter vector, along fixed-ratio rays. We illustrate these methods by characterizing the interactions of five organophosphorus pesticides (full-ray) as well as a subset of pesticides (reduced-ray) on a measure of motor activity. Copyright © 2004 John Wiley & Sons, Ltd. [source] Induction of rapid, activity-dependent neuronal,glial remodelling in the adult rat hypothalamus in vitroEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2003Sarah L. Langle Abstract The hypothalamic oxytocinergic system offers a remarkable model of morphological plasticity in the adult because its neurons and astrocytes undergo mutual remodelling in relation to differing physiological conditions. Among various factors involved in such plasticity, oxytocin (OT) itself appears of primary importance as its central administration resulted in morphological changes similar to those brought on by physiological stimuli. In the present study, we applied OT on acute hypothalamic slices from adult rats that included the supraoptic nucleus. Using ultrastructural morphometric analyses, we found that it induced a significant reduction of astrocytic coverage of OT neurons, leaving their surfaces directly juxtaposed, to an extent similar to that detected in vivo under conditions like lactation. These neuronal,glial changes were rapid and reversible, occurring within a few hours, and specifically mediated via OT receptors. They were potentiated by oestrogen and depended on calcium mobilization and de novo protein synthesis. Moreover, they depended on concurrent neuronal activation brought on by hyperosmotic stimulation or blockade of inhibitory GABAergic neurotransmission; they were inhibited by blockade of glutamatergic receptors. Taken together, our observations show that intrahypothalamic release of OT affects not only neuronal activation of the OT system but its morphological plasticity as well. Moreover, the activity dependence of the OT-induced changes strongly suggests that astrocytes can sense the level of activity of adjacent neurons and/or afferent input and this can subsequently act as a signal to bring on the neuronal and glial conformational changes. [source] Long-term trends in fish recruitment in the north-east Atlantic related to climate changeFISHERIES OCEANOGRAPHY, Issue 4 2007THOMAS BRUNEL Abstract This study investigates the temporal correspondence between the main patterns of recruitment variations among north-east Atlantic exploited fish populations and large-scale climate and temperature indices. It is of primary importance to know what changes in fish stock productivity can be expected in response to climate change, to design appropriate management strategies. The dominant patterns of recruitment variation were extracted using a standardized principal component analysis (PCA). The first principal component (PC) was a long-term decline, with a stepwise change occurring in 1987. A majority of Baltic Sea, North Sea, west of Scotland and Irish Sea populations, especially the gadoids, have followed this decreasing trend. On the contrary, some herring populations and the populations of boreal ecosystems have followed an opposite increasing trend. The dominant signal in north-east Atlantic sea surface temperature, also extracted by a PCA, was highly correlated with the increase in the Northern Hemisphere Temperature anomaly, which is considered to be an index of global warming. The first component of recruitment was inversely correlated with these changes in regional and global temperature. The second PC of recruitment was a decadal scale oscillation, which was not correlated with climate indicators. The analysis of correlations between population recruitment and local temperature also indicated that the dominant pattern of recruitment variation may be related to an effect of global warming. The influence of fishing on recruitment, via its effect on the spawning stock biomass (SSB), was also investigated by the analysis of correlations between fishing mortality, SSB and recruitment. Results indicate that fishing can be another factor explaining recruitment trends, probably acting in combination with the effect of climate, but cannot explain alone the patterns of recruitment variation found here. [source] Pond canopy cover: a resource gradient for anuran larvaeFRESHWATER BIOLOGY, Issue 3 2006LUIS SCHIESARI Summary 1.,The gradient in pond canopy cover strongly influences freshwater species distributions. This study tested the effects of canopy cover on the performance of two species of larval anurans, a canopy cover generalist (Rana sylvatica, the wood frog) and an open-canopy specialist (R. pipiens, the leopard frog), and tested which factors co-varying with canopy cover mediate these effects. 2.,A field transplant experiment demonstrated that canopy cover had negative performance effects on both species. However, leopard frogs, which grow faster than wood frogs in open-canopy ponds, were more strongly affected by closed-canopy pond conditions. 3.,Closed-canopy ponds had lower temperature, dissolved oxygen (DO), and food nutritional quality as indicated by carbon-to-nitrogen ratio (C : N) analysis of field-sampled food types, and of gut contents of transplanted larvae. 4.,Laboratory experiments demonstrated that higher temperature and food quality but not DO substantially increased larval growth. However, only food quality increased growth rates of leopard frogs more than wood frogs. 5.,The strong correlation of growth rates to gut content C : N in the field, and the similarity of growth curves as a function of resource quality in the field and laboratory, strongly suggest that resources are of primary importance in mediating intraspecific, and especially interspecific differences in performance across the canopy cover gradient. [source] Hard Macrocellular Silica Si(HIPE) Foams Templating Micro/Macroporous Carbonaceous Monoliths: Applications as Lithium Ion Battery Negative Electrodes and Electrochemical CapacitorsADVANCED FUNCTIONAL MATERIALS, Issue 19 2009Nicolas Brun Abstract By using Si(HIPEs) as hard, exotemplating matrices, interconnected macro-/microporous carbon monolith-type materials with a surface area of around 600,m2 g,1 are synthesized and shaped. The carbonaceous foams exhibit a conductivity of 20,S cm,1, addressed with excellent mechanical properties (Young's modulus of 0.2,GPa and toughness of 13,J g,1, when the carbon core is optimized). The above-mentioned specificities, combined with the fact that the external shape and size can be easily designed on demand, are of primary importance for applications. The functionality of these carbonaceous monoliths is tested as both an electrochemical capacitor and a lithium ion negative electrode. The electrochemical capacitors' voltage,current profiles exhibit a non-ideal rectangular response, confirming the double-layer behavior of the carbon studied, while the charge-discharge current profile of the electric double-layer capacitor is directly proportional to the scan where the current response during charge and discharge exhibits high reversibility. When acting as a lithium ion negative electrode, after initial irreversibility, a good cyclability is obtained, associated with a stable capacity of 200,mA h g,1 during the first 50 cycles at a reasonable current density (C/10). [source] Civil Servants, Economic Ideas, and Economic Policies: Lessons from ItalyGOVERNANCE, Issue 4 2005LUCIA QUAGLIA Building on theoretically oriented and empirically grounded research on two key macroeconomic institutions in Italy, this article explains how and why civil servants can engineer major policy changes, making a difference in a country's trajectory. Italy provides a challenging testing ground for this kind of analysis, as it is generally portrayed as a highly politicized system in which political parties and politicians fully control public policies. Three general lessons can be learned, the first being that the role of civil servants in changing modes of economic governance depends on the resources that they master in the system in which they operate. "Intangible assets" are of primary importance in complex and perceived technical policies, such as monetary and exchange rate policy, which have high potential for "technocratic capture." Second, in these policies, certain intangible assets, such as specific bodies of economic knowledge or policy paradigms, have a considerable impact on policy making. Third, besides interactions in international fora, the professional training of civil servants is a mainstream way through which economic policy beliefs circulate and gain currency, laying the foundations for policy shifts. By highlighting the importance of the intangible assets of macroeconomic institutions, this research makes an unorthodox contribution to the primarily economic literature on central bank independence. [source] Rainfall patterns and critical values associated with landslides in Povoação County (São Miguel Island, Azores): relationships with the North Atlantic OscillationHYDROLOGICAL PROCESSES, Issue 4 2008Rui Marques Abstract São Miguel Island (Azores) has been affected by hundreds of destructive landslide episodes in the last five centuries, triggered either by earthquakes, volcanic eruptions or rainfall episodes, which were responsible for many deaths and very important economic losses. Among the instability causes, meteorological factors are of primary importance on Povoação County, namely the high recurrence rate of calamitous rainfall triggering landslides. The most recent catastrophic episode took place on the 31st October 1997 when almost 1000 soil slips and debris flows were triggered, and 29 people died in the Ribeira Quente village. The role of rainfall on regional landslide activity was analysed applying cumulative rainfall methods. The method comprises the reconstruction of both absolute and calibrated antecedent rainfalls associated with each major landslide event. The critical rainfall combination (amount-duration) responsible for each landslide event was assessed and a rainfall critical threshold for landslide occurrence was calculated. Rainfall-triggered landslides in the study area are ruled by the function I = 144·06 D,0·5551, and they are related both to short duration precipitation events (1,3 days) with high average intensity (between 78 and 144 mm/day) and long-lasting rainfall episodes (1,5 months) with a lower intensity (between 9 and 22 mm/day). The impact of the North Atlantic Oscillation (NAO) on the regional precipitation regime was evaluated. It is shown that the monthly precipitation of São Miguel is largely modulated by the NAO mode presenting a significant negative correlation with the NAO index. This result arises from the NAO control on the travelling latitude of most storm tracks that cross the Northern Atlantic Ocean. Copyright © 2007 John Wiley & Sons, Ltd. [source] Mesoscale precipitation variability in the region of the European Alps during the 20th centuryINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2002Jürg Schmidli Abstract The purpose of this study is to construct and evaluate a new gridded analysis of precipitation that covers the entire region of the European Alps (43.2,48.8 ° N, 3.2,16.2 ° E), resolves the most prominent mesoscale variations (grid spacing 25 km) and extends with a monthly time-resolution over most of the 20th century (1901,90). The analysis is based on a reconstruction using the reduced-space optimal interpolation technique. It combines data from a high-resolution network over a restricted time period (1971,90) with homogeneous centennial records from a sparse sample of stations. The reconstructed fields account for 78% of the total variance in a cross-validation with independent data. The explained variance for individual grid points varies between 60 and 95%, with lower skills over the southern and western parts of the domain. For averages over 100 × 100 km2 subdomains, the explained variance increases to 90,99%. Comparison of the reconstruction with the CRU05 global analysis reveals good agreement with respect to the interannual variations of large subdomain averages (10 000,50 000 km2), some differences in decadal variations, especially for recent decades, and physically more plausible spatial patterns in the present analysis. The new dataset is exploited to depict 20th century precipitation variations and their correlations with the North Atlantic oscillation (NAO). A linear trend analysis (1901,90) reveals an increase of winter precipitation by 20,30% per 100 years in the western part of the Alps, and a decrease of autumn precipitation by 20,40% to the south of the main ridge. Correlations with the NAO index (NAOI) are weak and highly intermittent to the north and weak and more robust to the south of the main Alpine crest, indicating that changes in the NAOI in recent decades are not of primary importance in explaining observed precipitation changes. Copyright © 2002 Royal Meteorological Society [source] Temperature-frequency characteristics simulation of piezoelectric resonators and their equivalent circuits based on three-dimensional finite element modellingINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 6 2003N. Wakatsuki Abstract The electromechanical resonators made of piezoelectric crystals such as a quartz crystal are widely used for electronic devices. Their frequency,temperature characteristics are of primary importance for their applications to the frequency control devices. The present paper demonstrates numerical simulation for several types of resonators using 3-D Finite Element Modelling. The results are compared with the theoretical values whenever they are available. As they are electronic devices, the equivalent circuit representation is often favourable for describing the admittance at the electrical terminals which enables the circuit analysis including the effect of the temperature change by using commercially available circuit simulators. Copyright © 2003 John Wiley & Sons, Ltd. [source] A structured model for the simulation of bioreactors under transient conditionsAICHE JOURNAL, Issue 11 2009Jérôme Morchain Abstract Modeling the transient behavior of continuous culture is of primary importance for the scale-up of biological processes. Spatial heterogeneities increase with the reactor size and micro-organisms have to cope with a fluctuating environment along their trajectories within the bioreactor. In this article, a structured model for bioreactions expressed in terms of biological extensive variables is proposed. A biological variable is introduced to calculate the growth rate of the population. The value is updated on the basis of the difference between the composition in the liquid and biotic phase. The structured model is able to predict the transient behavior of different continuous cultures subject to various drastic perturbations. This performance is obtained with a minimum increase in the standard unstructured model complexity (one additional time constant). In the final part, the consequences of decoupling the growth rate from the substrate uptake rate are discussed. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Multivariate exploratory analysis of ordinal data in ecology: Pitfalls, problems and solutionsJOURNAL OF VEGETATION SCIENCE, Issue 5 2005János Podani Abstract Questions: Are ordinal data appropriately treated by multivariate methods in numerical ecology? If not, what are the most common mistakes? Which dissimilarity coefficients, ordination and classification methods are best suited to ordinal data? Should we worry about such problems at all? Methods: A new classification model family, OrdClAn (Ordinal Cluster Analysis), is suggested for hierarchical and non-hierarchical classifications from ordinal ecological data, e.g. the abundance/dominance scores that are commonly recorded in relevés. During the clustering process, the objects are grouped so as to minimize a measure calculated from the ranks of within-cluster and between-cluster distances or dissimilarities. Results and Conclusions: Evaluation of the various steps of exploratory data analysis of ordinal ecological data shows that consistency of methodology throughout the study is of primary importance. In an optimal situation, each methodological step is order invariant. This property ensures that the results are independent of changes not affecting ordinal relationships, and guarantees that no illusory precision is introduced into the analysis. However, the multivariate procedures that are most commonly applied in numerical ecology do not satisfy these requirements and are therefore not recommended. For example, it is inappropriate to analyse Braun-Blanquet abudance/dominance data by methods assuming that Euclidean distance is meaningful. The solution of all problems is that the dissimilarity coefficient should be compatible with ordinal variables and the subsequent ordination or clustering method should consider only the rank order of dissimilarities. A range of artificial data sets exemplifying different subtypes of ordinal variables, e.g. indicator values or species scores from relevés, illustrate the advocated approach. Detailed analyses of an actual phytosociological data set demonstrate the classification by OrdClAn of relevés and species and the subsequent tabular rearrangement, in a numerical study remaining within the ordinal domain from the first step to the last. [source] Biology and establishment of mountain shrubs on mining disturbances in the Rocky Mountains, USALAND DEGRADATION AND DEVELOPMENT, Issue 5 2003M. W. Paschke Abstract The Rocky Mountains of the western United States contain many economically important natural resources. Increasing development of these resources has lead to land degradation, which often requires restoration efforts. A common type of disturbance in this region is mineral extraction and these activities often occur in zones of vegetation dominated by shrubs. These mined lands have proven to be particularly challenging to restore to native shrub cover. Mountain shrubland species such as big sagebrush (Artemisia tridentata), antelope bitterbrush (Purshia tridentata), Saskatoon serviceberry (Amelanchier alnifolia), black chokecherry (Prunus virginiana), mountain mahogany (Cercocarpus montanus), and snowberry (Symphoricarpos sp.) are crucial species for wildlife in this region due to the seasonal dependence of many wildlife species on the mountain shrubland zones. The development of successful restoration techniques for these key shrub species is therefore important for the continued and sustainable utilization of natural resources in the Rocky Mountains. The purpose of this literature review is to provide a reference to land managers working on woody plant establishment on mining disturbances in mountain shrublands in the Rocky Mountains. This review covers the biology, ecology, and propagation of six shrub species that are of primary importance for meeting regulatory compliance in this region. Based upon this survey of the published literature, we conclude that successful establishment of these species has most often involved: (1) utilization of local shrub ecotypes, varieties or subspecies in reclamation efforts, (2) protection from browsing during the establishment phase, (3) strategies for avoiding herbaceous competition, and (4) providing a source of mutualistic soil organisms. Additional specific recommendations for each of these species are discussed. Copyright © 2003 John Wiley & Sons, Ltd. [source] Factors that identify survival after liver retransplantation for allograft failure caused by recurrent hepatitis C infectionLIVER TRANSPLANTATION, Issue 12 2004Guy W. Neff Hepatitis C virus (HCV) is becoming the most common indication for liver retransplantation (ReLTx). This study was a retrospective review of the medical records of liver transplant patients at our institution to determine factors that would identify the best candidates for ReLTx resulting from allograft failure because of HCV recurrence. The patients were divided into 2 groups on the basis of indication for initial liver transplant. Group 1 included ReLTx patients whose initial indication for LTx was HCV. Group 2 included patients who received ReLTx who did not have a history of HCV. We defined chronic allograft dysfunction (AD) as patients with persistent jaundice (> 30 days) beginning 6 months after primary liver transplant in the absence of other reasons. HCV was the primary indication for initial orthotopic liver transplantation (OLT) in 491/1114 patients (44%) from July 1996 to February 2004. The number of patients with AD undergoing ReLTx in Groups 1 and 2 was 22 and 12, respectively. The overall patient and allograft survival at 1 year was 50% and 75% in Groups 1 and 2, respectively (P = .04). The rates of primary nonfunction and technical problems after ReLTx were not different between the groups. However, the incidence of recurrent AD was higher in Group 1 at 32% versus 17% in Group 2 (P = .04). Important factors that predicted a successful ReLTx included physical condition at the time of ReLTx (P = .002) and Child-Turcotte-Pugh score (P = .008). In conclusion, HCV is associated with an increased incidence of chronic graft destruction with a negative effect on long-term results after ReLTx. The optimum candidate for ReLTx is a patient who can maintain normal physical activity. As the allograft shortage continues, the optimal use of cadaveric livers continues to be of primary importance. The use of deceased donor livers in patients with allograft failure caused by HCV remains a highly controversial issue. (Liver Transpl 2004;10:1497,1503.) [source] HALS in polyamide 6 polymerizationMACROMOLECULAR SYMPOSIA, Issue 1 2003Roberto Filippini Fantoni Abstract The use of Hindered Amine Light Stabilizers (HALS) directly in polyamide 6 polymerization can cause some problems. The following two problems were the focus of our project: 1) We investigated, from a theoretical point of view, the results of introducing directly one of the precursors of HALS into polyamide 6 polymerization. For the investigation, 4 amino-2,2,6,6-tetramethylpiperidine (triaceton-diamine or TAD) was chosen. We considered the TAD chain-ending effects and their influence on the total amount of amino chain-endings that can be titrated, a parameter of primary importance in the fibre field. 2) We examined the amide interchange reaction in the case of an HALS containing two amide groups, using a product available on the market, N,N,-bis(tetramethyl-4-piperidyl)isophtalamide. In this case we were able to generate a couple of equations that allows one to calculate the quantity of amide interchanged HALS. This was done by comparing the results (molecular weight and chain-endings analysis) of polymerization with and without HALS. [source] Ernst Florens Friedrich Chladni (1756,1827) and the origins of modern meteorite researchMETEORITICS & PLANETARY SCIENCE, Issue S9 2007Ursula B. Marvin These ideas violated two strongly held contemporary beliefs: 1) fragments of rock and metal do not fall from the sky, and 2) no small bodies exist in space beyond the Moon. From the beginning, Chladni was severely criticized for basing his hypotheses on historical eyewitness reports of falls, which others regarded as folk tales, and for taking gross liberties with the laws of physics. Ten years later, the study of fallen stones and irons was established as a valid field of investigation. Today, some scholars credit Chladni with founding meteoritics as a science; others regard his contributions as scarcely worthy of mention. Writings by his contemporaries suggest that Chladni's book alone would not have led to changes of prevailing theories; thus, he narrowly escaped the fate of those scientists who propose valid hypotheses prematurely. However, between 1794 and 1798, four falls of stones were witnessed and widely publicized. There followed a series of epoch-making analyses of fallen stones and "native irons" by the chemist Edward C. Howard and the mineralogist Jacques-Louis de Bournon. They showed that all the stones were much alike in texture and composition but significantly different from the Earth's known crustal rocks. Of primary importance was Howard's discovery of nickel in the irons and the metal grains of the stones. This linked the two as belonging to the same natural phenomenon. These chemical results, published in February 1802, persuaded some of the leading scientists in England, France, and Germany that bodies do fall from the sky. Within a few months, chemists in France reported similar results and a new field of study was inaugurated internationally, although opposition lingered on until April 1803, when nearly 3,000 stones fell at L'Aigle in Normandy and transformed the last skeptics into believers. Chladni immediately received full credit for his hypothesis of falls, but decades passed before his linking of falling bodies with fireballs received general acceptance. His hypothesis of their origin in cosmic space met with strong resistance from those who argued that stones formed within the Earth's atmosphere or were ejected by lunar volcanoes. After 1860, when both of these hypotheses were abandoned, there followed a century of debate between proponents of an interstellar versus a planetary origin. Not until the 1950s did conclusive evidence of their elliptical orbits establish meteorite parent bodies as members of the solar system. Thus, nearly 200 years passed before the questions of origin that Chladni raised finally were resolved. [source] Marvels, Mysteries, and Misconceptions of Vascular Compensation to Peripheral Artery OcclusionMICROCIRCULATION, Issue 1 2010MATTHEW A. ZIEGLER Microcirculation (2010) 17, 3,20. doi: 10.1111/j.1549-8719.2010.00008.x Abstract Peripheral arterial disease is a major health problem and there is a significant need to develop therapies to prevent its progression to claudication and critical limb ischemia. Promising results in rodent models of arterial occlusion have generally failed to predict clinical success and led to questions of their relevance. While sub-optimal models may have contributed to the lack of progress, we suggest that advancement has also been hindered by misconceptions of the human capacity for compensation and the specific vessels which are of primary importance. We present and summarize new and existing data from humans, Ossabaw miniature pigs, and rodents which provide compelling evidence that natural compensation to occlusion of a major artery (i) may completely restore perfusion, (ii) occurs in specific pre-existing small arteries, rather than the distal vasculature, via mechanisms involving flow-mediated dilation and remodeling (iii) is impaired by cardiovascular risk factors which suppress the flow-mediated mechanisms and (iv) can be restored by reversal of endothelial dysfunction. We propose that restoration of the capacity for flow-mediated dilation and remodeling in small arteries represents a largely unexplored potential therapeutic opportunity to enhance compensation for major arterial occlusion and prevent the progression to critical limb ischemia in the peripheral circulation. [source] How many species of cichlid fishes are there in African lakes?MOLECULAR ECOLOGY, Issue 3 2001George F. Turner Abstract The endemic cichlid fishes of Lakes Malawi, Tanganyika and Victoria are textbook examples of explosive speciation and adaptive radiation, and their study promises to yield important insights into these processes. Accurate estimates of species richness of lineages in these lakes, and elsewhere, will be a necessary prerequisite for a thorough comparative analysis of the intrinsic and extrinsic factors influencing rates of diversification. This review presents recent findings on the discoveries of new species and species flocks and critically appraises the relevant evidence on species richness from recent studies of polymorphism and assortative mating, generally using behavioural and molecular methods. Within the haplochromines, the most species-rich lineage, there are few reported cases of postzygotic isolation, and these are generally among allopatric taxa that are likely to have diverged a relatively long time in the past. However, many taxa, including many which occur sympatrically and do not interbreed in nature, produce viable, fertile hybrids. Prezygotic barriers are more important, and persist in laboratory conditions in which environmental factors have been controlled, indicating the primary importance of direct mate preferences. Studies to date indicate that estimates of alpha (within-site) diversity appear to be robust. Although within-species colour polymorphisms are common, these have been taken into account in previous estimates of species richness. However, overall estimates of species richness in Lakes Malawi and Victoria are heavily dependent on the assignation of species status to allopatric populations differing in male colour. Appropriate methods for testing the specific status of allopatric cichlid taxa are reviewed and preliminary results presented. [source] Layers of defense responses to Leptosphaeria maculans below the RLM1 - and camalexin-dependent resistancesNEW PHYTOLOGIST, Issue 2 2009Mattias Persson Summary ,,Plants have evolved different defense components to counteract pathogen attacks. The resistance locus resistance to Leptosphaeria maculans 1 (RLM1) is a key factor for Arabidopsis thaliana resistance to L. maculans. The present work aimed to reveal downstream defense responses regulated by RLM1. ,,Quantitative assessment of fungal colonization in the host was carried out using quantitative polymerase chain reaction (qPCR) and GUS expression analyses, to further characterize RLM1 resistance and the role of salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) in disease development. Additional assessments of A. thaliana mutants were performed to expand our understanding of this pathosystem. ,,Resistance responses such as lignification and the formation of vascular plugs were found to occur in an RLM1 -dependent manner, in contrast to the RLM1 -independent increase in reactive oxygen species at the stomata and hydathodes. Analyses of mutants defective in hormone signaling in the camalexin-free rlm1Lerpad3 background revealed a significant influence of JA and ET on symptom development and pathogen colonization. ,,The overall results indicate that the defense responses of primary importance induced by RLM1 are all associated with physical barriers, and that responses of secondary importance involve complex cross-talk among SA, JA and ET. Our observations further suggest that ET positively affects fungal colonization. [source] Perioperative care of a patient with Beare,Stevenson syndromePEDIATRIC ANESTHESIA, Issue 12 2005SARA UPMEYER DO Summary Beare,Stevenson syndrome is a craniofacial syndrome consisting of a specific pattern of craniosynostosis resulting in a cloverleaf skull deformity and hydrocephalus, down-slanting palpebral fissures, proptosis, hypertelorism, strabismus, dysmorphic ears, choanal atresia, cleft palate, cutis gyratum, acanthosis nigricans, and abnormal genitalia. Its primary cause has been identified as a single amino acid substitution in fibroblast growth factor receptor 2. Of primary importance to the anesthesiologist are issues related to airway management resulting from midface hypoplasia, choanal atresia, and airway abnormalities (tracheal stenosis). Additional issues affecting airway management include associated cervical spine and foramen magnum abnormalities. The authors present their experience caring for a patient with Beare,Stevenson syndrome and discuss the anesthesia care of these patients. [source] Fluence Rate or Cumulative Dose?PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2007Vulnerability of Larval Northern Pike (Esox lucius) to Ultraviolet Radiation Newly hatched larvae of northern pike were exposed in the laboratory to four fluence rates of ultraviolet radiation (UVR; 290,400 nm) over three different time periods, resulting in total doses ranging from 3.0 ± 0.2 to 63.0 ± 4.4 kJ·m,2. Mortality and behavior of the larvae were followed for 8,12 days, and growth measured at the end of the experiment. Also, the principle of reciprocity,that the UVR-induced mortality depends on the cumulative dose, independent of fluence rate,was tested. Fluence rates higher than 1480 ± 150 mW·m,2 caused mortality and growth retardation. The highest fluence rate (3040 ± 210 mW·m,2) caused 100% mortality in 5 days. All fluence rates caused behavioral disorders, which led to death at fluence rates higher than 1480 mW·m,2. Reciprocity failure occurred with the lowest and highest dose (550 ± 45 and 3040 ± 210 mW·m,2, respectively). The results show that fluence rate is of primary importance when assessing the UVR-related risk. [source] The role of cytoplasmic streaming in symplastic transportPLANT CELL & ENVIRONMENT, Issue 1 2003W. F. PICKARD ABSTRACT The distributing of materials throughout a symplastic domain must involve at least two classes of transport steps: plasmodesmatal and cytoplasmic. To underpin the latter, the most obvious candidate mechanisms are cytoplasmic streaming and diffusion. The thesis will be here advanced that, although both candidates clearly do transport cytoplasmic entities, the cytoplasmic streaming per se is not of primary importance in symplastic transport but that its underlying molecular motor activity (of which the streaming is a readily visible consequence) is. Following brief tutorials on low Reynolds number flow, diffusion, and targeted intracytoplasmic transport, the hypothesis is broached that macromolecular and vesicular transport along actin trackways is both the cause of visible streaming and the essential metabolically driven cytoplasmic step in symplastic transport. The concluding discussion highlights four underdeveloped aspects of the active cytoplasmic step: (i) visualization of the real-time transport of messages and metabolites; (ii) enumeration of the entities trafficked; (iii) elucidation of the routing of the messages and metabolites within the cytoplasm; and (iv) transference of the trafficked entities from cytoplasm into plasmodesmata. [source] The Effect of Bed Temperature on Mass Transfer between the Bubble and Emulsion Phases in a Fluidized BedTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2003Wenyuan Wu Abstract The rate of interphase mass transfer between the bubble and emulsion phases of a bubbling fluidized bed is of primary importance in all models for fluidized bed reactors. Many experimental studies have been reported, however, all these investigations have been carried out in fluidized beds operated at room temperature. In this work, the effect of the bed temperature on the interphase mass transfer is reported. Single bubbles containing argon , used as a tracer , were injected into an incipiently fluidized bed maintained at the required temperature. The change in argon concentration in the bubble was measured using a suction probe connected to a mass spectrometer. The effects of bed particle type and size, bubble size, and bed temperature on the mass transfer coefficient were examined experimentally. The interphase mass transfer coefficient was found to decrease with the increase in bed temperature and bubble size, and increase slightly with increase in particle size. Experimental data obtained in this study were compared with some frequently used correlations for estimation of the mass transfer coefficient. Le taux de transfert de matière interphasique entre les phases à bulles et à émulsion d'un lit fluidisé bullant est de première importance dans tous les modèles de réacteurs à lits fluidisés. Beaucoup d'études expérimentales ont été présentées; toutefois, toutes ces recherches ont été menées dans des lits fluidisés fonctionnant à la température ambiante. Dans ce travail, on décrit l'effet de la température du lit sur le taux de transfert de matière. Des bulles simples contenant de l'argon – utilisé comme traceur – ont été injectées dans un lit fluidisé naissant maintenu à la température requise. Le changement de concentration d'argon dans la bulle est mesuré à l'aide d'une sonde de succion reliée à un spectromètre de masse. Les effets du type et de la taille des particules de lit, de la taille des bulles et de la température de lit sur le coefficient de transfert de matière sont examinés de façon expérimentale. On a trouvé que le coefficient de transfert de matière interphasique diminuait avec l'augmentation de la température du lit et de la taille des bulles, et augmentait légèrement avec l'augmentation de la taille des particules. Les données expérimentales obtenues dans cette étude sont comparées avec quelques corrélations fréquemment utilisées pour l'estimation du coefficient de transfert de matière. [source] Rural Bioethical Issues of the Elderly: How Do They Differ From Urban Ones?THE JOURNAL OF RURAL HEALTH, Issue 4 2001Jacqueline J. Glover Ph.D. ABSTRACT: Typical ethical issues in health care for the elderly include decision making for elderly patients with and without capacity, advance directives, the use of life-sustaining technologies, and questions of access to services and justice. Obviously the same issues are relevant for elderly patients in rural settings. But the unique features of rural living add another dimension to ethical discourse and the care of patients, namely the primary importance of relationships. Rural bioethics is based on an ethic of familiarity, which alters our attention to such issues as confidentiality, multiple relationships, scope of practice, and access issues. The following article briefly outlines the unique features of rural bioethics and provides a case analysis. [source] SNP Selection for Association Studies: Maximizing Power across SNP Choice and Study SizeANNALS OF HUMAN GENETICS, Issue 6 2005F. Pardi Summary Selection of single nucleotide polymorphisms (SNPs) is a problem of primary importance in association studies and several approaches have been proposed. However, none provides a satisfying answer to the problem of how many SNPs should be selected, and how this should depend on the pattern of linkage disequilibrium (LD) in the region under consideration. Moreover, SNP selection is usually considered as independent from deciding the sample size of the study. However, when resources are limited there is a tradeoff between the study size and the number of SNPs to genotype. We show that tuning the SNP density to the LD pattern can be achieved by looking for the best solution to this tradeoff. Our approach consists of formulating SNP selection as an optimization problem: the objective is to maximize the power of the final association study, whilst keeping the total costs below a given budget. We also propose two alternative algorithms for the solution of this optimization problem: a genetic algorithm and a hill climbing search. These standard techniques efficiently find good solutions, even when the number of possible SNPs to choose from is large. We compare the performance of these two algorithms on different chromosomal regions and show that, as expected, the selected SNPs reflect the LD pattern: the optimal SNP density varies dramatically between chromosomal regions. [source] Quantification of vitellin/vitellogenin-like proteins in the oyster Crassostrea corteziensis (Hertlein 1951) as a tool to predict the degree of gonad maturityAQUACULTURE RESEARCH, Issue 6 2009Fabiola G. Arcos Abstract The oyster's reproductive process is poorly documented, especially in terms of a quantitative approach. In recent years, investigations with this species have been directed at determining important reproductive factors. Within this scope, techniques that allow standardized and accurate quantitative estimations of gonad development have become of primary importance. In this study, the histological characteristics and the levels of vitellin/vitellogenin-like proteins (Vn/Vtg) from ovaries of the Mexican Pacific ,pleasure' oyster Crassostrea corteziensis (Hertlein 1951) were analysed during different stages of gonad maturation using quantitative histological techniques and an enzyme-linked immunosorbent assay. This was performed in order to evaluate a possible quantitative tool to predict the degrees of gonad maturity and to analyse the biological implications of the findings relative not only to broodstock conditioning but also to natural populations. Using this information, we expect to be able to undertake further research on different reproductive aspects of this oyster species, including, among others, evaluation of the response in Vn/Vtg concentrations to different diets and environmental conditions during laboratory conditioning. [source] Tolerance response to water pH in larvae of two marine fish species, gilthead seabream, Sparus aurata (L.) and Senegal sole, Solea senegalensis (Kaup), during developmentAQUACULTURE RESEARCH, Issue 10 2002G Parra Abstract Gilthead seabream, Sparus aurata (L.) and Senegal sole, Solea senegalensis (Kaup) are two fish of primary importance in Mediterranean aquaculture. In the present study, the larvae of these species were exposed to different rearing-water pH during 24 h to examine their tolerance. The 24-h pHL50 values were calculated with low and high pH values at 7, 20 and 32 days after hatching (DAH) in S. senegalensis larvae, and 12, 20 and 52 DAH in S. aurata larvae. Low 24-h pHL50 values ranged between 4.88 and 5.76, whereas high 24-h pHL50 values ranged between 8.94 and 9.57 in S. senegalensis larvae. S. aurata larvae showed values of low 24-h pHL50 that ranged between 4.82 and 5.55, whereas values of high 24-h pHL50 ranged between 8.66 and 9.26. Both species showed similar tolerance response at all the tested ages. The high 24-h pHL50 values found were close to pH values that eventually can be reached in the rearing tanks. The pH should be carefully controlled in rearing water during the first development stages of both species. [source] | |||||||||||||||||||||||||||||||||||||||||||