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Substantial Influence (substantial + influence)
Selected AbstractsThermal, phase transition and spectral studies in erythromycin pseudopolymorphs: dihydrate and acetone solvateCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2006Zhanzhong Wang Abstract The thermal, phase transition and spectral studies of erythromycin A dihydrate and acetone solvate were performed by Differential Scanning calorimetry (DSC), Thermo Gravimetry (TG-DTA), X-Ray Powder Diffraction (XRPD) and Fourier Transform Infra-Red (FTIR) spectrum. The non-thermal kinetic analysis of erythromycin A dihydrate was carried out by DSC at different heating rates in dynamic nitrogen atmosphere. The result showed that heating rate has substantial influence on the thermal behavior of erythromycin dihydrate. The Arrhenius parameters were estimated according to the Kissinger method. Corresponding to dehydration of dihydrate, melting of dehydrated dihydrate, phase transition from dehydrated dihydrate to anhydrate, and melting of anhydrate, the calculated activation energy were 39.60, 269.85, 261.23, and 582.16 kJmol,1, the pre-exponential factors were 3.46 × 103, 8.06 × 1032, 9.23 × 1030, and 7.29 × 1063 s,1, respectively. Ozawa method was used to compare activation energy values calculated by Kissinger method. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Reflections on smoking relapse researchDRUG AND ALCOHOL REVIEW, Issue 1 2006SAUL SHIFFMAN Abstract This paper presents personal reflections on the history, current status and the future of research on smoking relapse. Relapse was traditionally viewed primarily as an outcome, to be reduced with increased treatment. In the 1980s, relapse research was invigorated by a focus on the process of relapse, focusing on the specific situations in which lapses to smoking occurred, and on the processes that mediated progression from a lapse to a relapse. This line of research had substantial influence on treatment, but has currently been displaced by a return to a pure outcomes-focus, driven in part by the practical need to find treatments that work and to package them for dissemination. At the same time, technological and methodological developments have enabled detailed monitoring of experience and behaviour throughout the relapse process, and progression of these developments will make monitoring of relapse process compelling in the future. The need to understand how interventions work will also drive a resurgence of research on the relapse process. Finally, the same technological and conceptual developments that enable detailed monitoring of behaviour will spawn the development of just-in-time interventions that are offered and implemented as needed, rather than being addressed in the abstract in advance of the need [source] CONTRIBUTIONS AND ELECTIONS WITH NETWORK EXTERNALITIESECONOMICS & POLITICS, Issue 1 2005Adam Meirowitz This paper develops a model of campaign contributions and electoral competition. Contributors have separable preferences over policy and the electoral success of the candidate they support, as in influence buying. Policy preferences are single peaked over a single policy dimension. A candidate's chances of victory are increasing in the relative size of her war chest. In equilibrium, potential contributors balance incentives to donate to a candidate that is desirable on policy grounds and ensuring that they back the likely winner. With exogenous candidate positions, we find conditions under which, in equilibrium, contributors donate to the candidate that is less desirable on policy grounds solely because they consider the candidate viable. We also find that there is a degree of indeterminacy, wherein multiple equilibria inducing different lotteries over the final policy often exist. With endogenous candidate locations, we find that while median policies are always supportable as equilibrium, it is often the case that any pair of candidate locations is supportable in equilibrium. These results suggest that in settings with substantial influence buying, median policy interests may not be represented. [source] Voltammetric Studies of Parallel Electrode Processes Under Low Ionic Strength Conditions.ELECTROANALYSIS, Issue 7 2006Influence of Convection Abstract It is known that either a very strong enhancement or an almost complete depression of the height of one of two waves can be obtained when two analytes (one appropriately charged and one uncharged) are present in a quiet solution containing no supporting electrolyte. In this paper we examine whether these effects can be extended for solutions with forced convection. Three two-analyte mixtures were examined voltammetrically under conditions of no added supporting electrolyte and added convection. The first mixture (1,1,-ferrocenedimethanol and ferrocenesulfonate anion) changes its total charge from ,1 to +1 after electrooxidation of both components. Under all applied conditions, the introduction of convection caused an increase of both waves without changing the wave height ratio. A similar behavior was observed for the mixture of ferrocene and 1,1,-ferrocenedimethanol. For this system the total charge changes from 0 to +2. A substantial influence of convection on the ratio of two waves was found for the third mixture: ferrocene and ferrocenylmethyltrimethylammonium cation (total charge changes from +1 to +3). For this system the convection strongly depressed the migrational effects. The obtained experimental results were verified with simulations using software MIOTRAS. This software is capable of modeling diffusion, migration, convection and following homogenous reactions. The agreement between experiment and simulations was fairly good. [source] Human leukocyte antigen,associated sequence polymorphisms in hepatitis C virus reveal reproducible immune responses and constraints on viral evolution,HEPATOLOGY, Issue 2 2007Joerg Timm CD8+ T cell responses play a key role in governing the outcome of hepatitis C virus (HCV) infection, and viral evolution enabling escape from these responses may contribute to the inability to resolve infection. To more comprehensively examine the extent of CD8 escape and adaptation of HCV to human leukocyte antigen (HLA) class I restricted immune pressures on a population level, we sequenced all non-structural proteins in a cohort of 70 chronic HCV genotype 1a-infected subjects (28 subjects with HCV monoinfection and 42 with HCV/human immunodeficiency virus [HIV] coinfection). Linking of sequence polymorphisms with HLA allele expression revealed numerous HLA-associated polymorphisms across the HCV proteome. Multiple associations resided within relatively conserved regions, highlighting attractive targets for vaccination. Additional mutations provided evidence of HLA-driven fixation of sequence polymorphisms, suggesting potential loss of some CD8 targets from the population. In a subgroup analysis of mono- and co-infected subjects some associations lost significance partly due to reduced power of the utilized statistics. A phylogenetic analysis of the data revealed the substantial influence of founder effects upon viral evolution and HLA associations, cautioning against simple statistical approaches to examine the influence of host genetics upon sequence evolution of highly variable pathogens. Conclusion: These data provide insight into the frequency and reproducibility of viral escape from CD8+ T cell responses in human HCV infection, and clarify the combined influence of multiple forces shaping the sequence diversity of HCV and other highly variable pathogens. (HEPATOLOGY 2007.) [source] Employer responses to union organising: patterns and effectsHUMAN RESOURCE MANAGEMENT JOURNAL, Issue 1 2010Edmund Heery This article presents original research on employer responses to trade union organising campaigns in the United Kingdom. The evidence indicates that there is no single response, with employers in some cases seeking to block and in others support union activity. These different patterns are strongly path dependent and reflect the prior degree of exposure to trade unionism of workplaces targeted for organising. Another finding is that employer responses co-vary with union approaches to organising, such that when the employer adopts adversarial tactics so does the union. The militancy of both parties, it seems, is mutually reinforcing. Finally, the evidence points to substantial influence of employer responses over the outcomes of organising. When employers are supportive then campaigns tend to be more successful, measured on a range of criteria. When the employer is hostile unions find it difficult to make progress and encounter particular difficulties in securing recognition. [source] A comparison of spatial interpolation methods to estimate continuous wind speed surfaces using irregularly distributed data from England and WalesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2008W. Luo Abstract Seven methods of spatial interpolation were compared to determine their suitability for estimating daily mean wind speed surfaces, from data recorded at nearly 190 locations across England and Wales. The eventual purpose of producing such surfaces is to help estimate the daily spread of pathogens causing crop diseases as they move across regions. The interpolation techniques included four deterministic and three geostatistical methods. Quantitative assessment of the continuous surfaces showed that there was a large difference between the accuracy of the seven interpolation methods and that the geostatistical methods were superior to deterministic methods. Further analyses, testing the reliability of the results, showed that measurement accuracy, density, distribution and spatial variability had a substantial influence on the accuracy of the interpolation methods. Independent wind speed data from ten other dates were used to confirm the robustness of the best interpolation methods. © Crown copyright 2007. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd. [source] Cardiovascular changes and physiological response during nitrite exposure in rainbow troutJOURNAL OF FISH BIOLOGY, Issue 1 2001S. Aggergaard Nitrite-exposed (1 mM) rainbow trout Oncorhynchus mykiss fell into two distinct groups with regard to susceptibility and physiological response. Group 1 accumulated nitrite in plasma to a concentration of 2·9 mM within 24 h and died before 48 h. Group 2 survived for 96,144 h, and the accumulation of nitrite was slower, levelling off at a concentration c. 2·3 mM at 72 h. Methaemoglobin (metHb) formation was faster in group 1 than in group 2, but both groups had a metHb fraction c. 70% before dying. The extracellular electrolyte balance was perturbed significantly only in group 1, where plasma [Cl - ] decreased and plasma [K+] increased. Heart rate increased rapidly, more in group 1 than in group 2. The tachycardia occurred before any significant changes in metHb or [K+] had developed, suggesting that it was due to nitrite-induced vasodilation, possibly via nitric oxide generated from nitrite, that was countered by an increased cardiac pumping to re-establish blood pressure. Arterial blood pressure and pulse pressure were accordingly kept reasonably constant. Heart rate variability was significantly depressed in group 1. The ventilation rate was significantly increased after 9 h of nitrite exposure in group 1, while the ventilation in group 2 did not increase significantly before 21 h. The data reveal that nitrite has substantial influence on the cardio-respiratory function in fishes. [source] Impact of deposit ageing on thermal fouling: Lumped parameter modelAICHE JOURNAL, Issue 2 2010Edward. Abstract The thermal and hydraulic performance of heat exchangers can be seriously impaired by the formation of fouling deposits on the heat transfer surfaces. The thermal effect of fouling can be complicated when the deposit is subject to ageing, represented here as a change in deposit thermal conductivity (but not thickness) over time. In this article, we revisit the ageing concept for crude oil fouling proposed by Nelson (Refiner Nat Gas Manufacturer. 1934;13:271,276, 292,298), using a numerical model incorporating first order kinetics to generate quantitative comparisons of different ageing rates. Results are reported for lumped parameter systems (which also simulate point measurement methods commonly used in laboratory testing) that demonstrate that ageing can have a substantial influence on the rate of heat transfer and hence on the surface temperature and rate of fouling. Rapid ageing (compared with the rate of deposition) does not pose problems, but slow ageing, or the use of constant heat fluxes in experiments, can lead to modified thermal fouling behavior. It is concluded that deposit ageing dynamics should be considered alongside deposition rate dynamics when interpreting experimental fouling data and when modeling fouling behavior in support of heat exchanger design or operation. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Allogenic and autogenic influences upon riparian vegetation dynamicsAREA, Issue 4 2006Robert A Francis Riparian vegetation dynamics are regarded as being driven by allogenic hydrogeomorphological factors, with autogenic (plant-induced) influences becoming more important as landform stability is achieved. Autogenic processes, however, may have a substantial influence on both plant dynamics and the river environment from the earliest stages of plant establishment. Various aspects of both allogenic and autogenic processes in riparian vegetation dynamics are discussed here; in particular how plants may promote bank stability and sedimentation, and river island development. Riparian restoration often fails to incorporate autogenic processes, thereby restricting the re-establishment of natural functioning, and further interdisciplinary work is needed to address this. [source] Soil conservation in Polylepis mountain forests of Central Argentina: Is livestock reducing our natural capital?AUSTRAL ECOLOGY, Issue 4 2010DANIEL RENISON Abstract Mountain forests and their soils provide ecological services such as maintenance of biodiversity, provision of clean water, carbon capture and forage for livestock rearing, which is one of the principal economic activities in mountain areas. However, surprisingly little is known about livestock impact in South American mountain forest soils. With the aim of understanding how livestock and topography influence patterns of forest cover, soil compaction, soil loss and soil chemical properties, we analysed these parameters in 100 Polylepis australis woodland plots situated in the humid subtropical mountains of Central Argentina. We used distance from the nearest ranch as an objective index of historical livestock impact and measured standard topographic variables. Our main results reveal that distance from ranch in all cases partly explains tree canopy cover, soil loss, soil compaction and soil chemical properties; suggesting a strong negative effect of livestock. Intermediate altitudes had more tree canopy cover, while landscape roughness , a measure of the variability in slope inclination and aspect , was negatively associated to soil impedance and acidity, and positively associated to soil organic matter content. Finally, flatter areas were more acid. We conclude that livestock has had a substantial influence on forest soil degradation in the Mountains of Central Argentina and possibly other similar South American mountains. Soil degradation should be incorporated into decision making when considering long-term forest sustainability, or when taking into account retaining livestock for biodiversity conservation reasons. Where soil loss and degradation are ongoing, we recommend drastic reductions in livestock density. [source] Dynamische Steifigkeit und Dämpfung von PfahlgruppenBAUTECHNIK, Issue 2 2009Hamid Sadegh-Azar Dr.-Ing. Geotechnik; Bodenmechanik Abstract In diesem Beitrag werden die dynamische Steifigkeit und Dämpfung von Pfahlgruppen und ihre Auswirkung auf die Auslegung und Wirtschaftlichkeit der Pfahlgründung selbst und der Bauwerke darauf untersucht. Die Berechungen werden mit der sogenannten "Thin-Layer-Method", einer sehr leistungsfähigen Berechnungsmethode im Frequenzbereich, durchgeführt (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Dynamic stiffness and damping properties of pile groups. The dynamic stiffness and damping properties of pile-groups have been investigated in this paper. Also, the substantial influence of these properties on an economic structure and foundation design is demonstrated. The analysis has been carried out using the "Thin-Layer-Method", which is a very efficient and powerful analysis procedure in frequency domain. [source] The identification of enzyme targets for the optimization of a valine producing Corynebacterium glutamicum strain using a kinetic modelBIOTECHNOLOGY PROGRESS, Issue 3 2009Jørgen Barsett Magnus Abstract The enzyme targets for the rational optimization of a Corynebacterium glutamicum strain constructed for valine production are identified by analyzing the control of flux in the valine/leucine pathway. The control analysis is based on measurements of the intracellular metabolite concentrations and on a kinetic model of the reactions in the investigated pathway. Data-driven and model-based methods are used and evaluated against each other. The approach taken gives a quantitative evaluation of the flux control and it is demonstrated how the understanding of flux control is used to reach specific recommendations for strain optimization. The flux control coefficients (FCCs) with respect to the valine excretion rate were calculated, and it was found that the control is distributed mainly between the acetohydroxyacid synthase enzyme (FCC = 0.32), the branched chain amino acid transaminase (FCC = 0.27), and the exporting translocase (FCC = 0.43). The availability of the precursor pyruvate has substantial influence on the valine flux, whereas the cometabolites are less important as demonstrated by the calculation of the respective response coefficients. The model is further used to make in-silico predictions of the change in valine flux following a change in enzyme level. A doubling of the enzyme level of valine translocase will result in an increase in valine flux of 31%. By optimizing the enzyme levels with respect to valine flux it was found that the valine flux can be increased by a factor 2.5 when the optimal enzyme levels are implemented. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] A Novel Approach for Chemical Vapor Synthesis of ZnO Nanocrystals: Optimization of Yield, Crystallinity,CHEMICAL VAPOR DEPOSITION, Issue 7-9 2009Moazzam Ali Abstract The experimental yield of ZnO nanocrystals decreases drastically with increasing reactor temperature in a typical chemical vapor synthesis (CVS) of ZnO nanocrystals from diethylzinc. A novel CVS set-up , a microwave plasma combined with a hot-wall zone , is described to minimize the loss of particles at higher reactor temperatures. The powder samples have been characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). It is observed that the synthesis set-up and reaction temperature have substantial influence not only on yield but also on crystallite size and crystallinity of the pure wurtzite-type ZnO nanocrystals. The lattice constants of ZnO nanocrystals increase with decreasing crystallite size. Defect densities (twin and stacking faults), as well as microstrain, decrease with increasing reactor temperature, whereas crystallinity increases. [source] | |||||||||||||||||||