Only True (only + true)

Distribution by Scientific Domains


Selected Abstracts


Duverger's Laws: Between social and institutional determinism

EUROPEAN JOURNAL OF POLITICAL RESEARCH, Issue 1 2006
VIRGÍLIO AFONSO DA SILVA
The purpose of this article is to relocate Duverger's Laws within the debate about the effects of electoral systems on the number of parties. Although Duverger's theory has always been seen as the best example of a purely institutionalist approach to the issue, it is possible to argue that this is only true if one overemphasises the meaning of the laws without considering Duverger's justification and explanations for them. However, if one takes into consideration not only the laws, but also Duverger's theories about the effects of electoral systems on the number of parties as a whole, one can argue that his theses do not have a purely institutionalist character and can therefore coexist with theories that try to take into account variables other than electoral rules. [source]


Thermodynamic analysis of binding of p -substituted benzamidines to trypsin

FEBS JOURNAL, Issue 6 2001
Reinskje Talhout
Understanding the structural basis of inhibitor,enzyme interactions, important for the design of new drugs, requires a complete thermodynamic characterization of the binding process as well as a description of the structure of the complex. In this paper, the binding of p -substituted benzamidinium derivatives to the structurally well-characterized serine proteinase bovine pancreatic trypsin has been studied using isothermal titration calorimetry. These experiments have permitted a complete characterization of the temperature dependence of the inhibitor-binding thermodynamics. At 25 °C, both the enthalpy and entropy of binding are favourable for all studied derivatives, but this is only true for a relatively narrow temperature range. As binding is characterized by a negative change in heat capacity, the process is characterized by enthalpy,entropy compensation, resulting in a change of the net thermodynamic driving force for association from entropic to enthalpic with increasing temperature. These phenomena are not unusual when hydrophobic forces play an important role. The trend in the relative binding potencies can, to a significant extent, be attributed to the electron-donating/withdrawing character of the substituent at the para position, as shown by the Hammett plot for the different inhibitors; the more polar the p -substituted benzamidine, the less potent it will be as a trypsin inhibitor. This behaviour might result from a bulk solvation effect, meaning that the more polar, lower potency inhibitors will be more stabilized in water than the less polar, higher potency inhibitors. [source]


Erosion models: quality of spatial predictions

HYDROLOGICAL PROCESSES, Issue 5 2003
Victor Jetten
Abstract An Erratum has been published for this article in Hydrological Processes 18(3) 2004, 595. An overview is given on the predictive quality of spatially distributed runoff and erosion models. A summary is given of the results of model comparison workshops organized by the Global Change and Terrestrial Ecosystems Focus 3 programme, as well as other results obtained by individual researchers. The results concur with the generally held viewpoint in the literature that the predictive quality of distributed models is moderately good for total discharge at the outlet, and not very good for net soil loss. This is only true if extensive calibration is done: uncalibrated results are generally bad. The more simple lumped models seem to perform equally well as the more complex distributed models, although the latter produce more detailed spatially distributed results that can aid the researcher. All these results are outlet based: models are tested on lumped discharge and soil loss or on hydrographs and sedigraphs. Surprisingly few tests have been done on the comparison of simulated and modelled erosion patterns, although this may arguably be just as important in the sense of designing anti-erosion measures and determining source and sink areas. Two studies are shown in which the spatial performance of the erosion model LISEM (Limburg soil erosion model) is analysed. It seems that: (i) the model is very sensitive to the resolution (grid cell size); (ii) the spatial pattern prediction is not very good; (iii) the performance becomes better when the results are resampled to a lower resolution and (iv) the results are improved when certain processes in the model (in this case gully incision) are restricted to so called ,critical areas', selected from the digital elevation model with simple rules. The difficulties associated with calibrating and validating spatially distributed soil erosion models are, to a large extent, due to the large spatial and temporal variability of soil erosion phenomena and the uncertainty associated with the input parameter values used in models to predict these processes. They will, therefore, not be solved by constructing even more complete, and therefore more complex, models. However, the situation may be improved by using more spatial information for model calibration and validation rather than output data only and by using ,optimal' models, describing only the dominant processes operating in a given landscape. Copyright © 2003 John Wiley & Sons, Ltd. [source]


Spatial congruence of ecological transition at the regional scale in South Africa

JOURNAL OF BIOGEOGRAPHY, Issue 5 2004
Berndt J. Van Rensburg
Abstract Aim, To determine whether patterns of avian species turnover reflect either biome or climate transitions at a regional scale, and whether anthropogenic landscape transformation affects those patterns. Location South Africa and Lesotho. Methods, Biome and land transformation data were used to identify sets of transition areas, and avian species occurrence data were used to measure species turnover rates (, -diversity). Spatial congruence between areas of biome transition, areas of high vegetation heterogeneity, high climatic heterogeneity, and high , -diversity was assessed using random draw techniques. Spatial overlap in anthropogenically transformed areas, areas of high climatic heterogeneity and high , -diversity areas was also assessed. Results, Biome transition areas had greater vegetation heterogeneity, climatic heterogeneity, and , -diversity than expected by chance. For the land transformation transition areas, this was only true for land transformation heterogeneity values and for one of the , -diversity measures. Avian presence/absence data clearly separated the biome types but not the land transformation types. Main conclusions, Biome edges have elevated climatic and vegetation heterogeneity. More importantly, elevated , -diversity in the avifauna is clearly reflected in the heterogeneous biome transition areas. Thus, there is spatial congruence in biome transition areas (identified on vegetation and climatic grounds) and avian turnover patterns. However, there is no congruence between avian turnover and land transformation transition areas. This suggests that biogeographical patterns can be recovered using modern data despite landscape transformation. [source]


The Influence of In-Laws on Change in Marital Success

JOURNAL OF MARRIAGE AND FAMILY, Issue 3 2001
Chalandra M. Bryant
This study prospectively examines the association between discord with in-laws and the long-term relationship success of husbands and wives who had been married for an average of almost 2 decades. We hypothesized that the quality of spouses' relationships with their parents-in-law would predict spouses' marital success. In addition, this study underscores the causal role of in-laws by examining the influence of marital success on relationships with in-laws. For wives, discord with mothers- and fathers-in-law predicted own perceptions of marital success at a later time period. Results were slightly different for husbands' discord with fathers-in-law. The reverse (marital success predicting less discord with in-laws) was only true for husbands. The study also explored the influence of spouses' discord with in-laws on partners' perceptions of marital success. These are among the first prospective, longitudinal findings demonstrating that, even in long-term marriages, conflicts in extended family relations will erode marital stability, satisfaction, and commitment over time. [source]


The Quenched Instationary Polymerization Systems (QUIPS)

MACROMOLECULAR THEORY AND SIMULATIONS, Issue 2-3 2003
Irene Schnöll-Bitai
Abstract The common element of quenched instationary polymerization systems is that at a given time all radicals present are deactivated by an efficient and fast quench reaction. Quenched instationary polymerizations can be carried out in a variety of ways distinguished by the way periods differing in their initiation characteristics are combined. The total chain length distribution of the resulting polymer is always the sum of the quenched radical and polymer chain length distribution. This distribution is either completely or at least partially dominated by the contribution of the quenched radical spectrum. Depending on the experimental conditions monomodal or multimodal distributions are obtained which can be characterized by their extrema (maximum, points of inflection) and peak widths (absolute, relative). The location of the extrema are related to the experimental parameters and can be used in an unambiguous way for the direct determination of the rate constant of propagation. Absolute peak widths (defined as the difference between two succeeding points of inflection) are invariant quantities with respect to the number, molar mass and hyper distribution which is only true for Poisson (and narrow Gauss) distributions. Relative peak widths are a valuable tool for the direct determination of axial dispersion which occurs in size exclusion chromatography. Comparison of experimental and ideal relative peak widths can be used for the direct determination of the axial dispersion. The influence of the type of termination and [R0] (termination by combination) on the total (number) chain length distribution for single , -pulse initiation. [source]


Resource allocation and fluid intelligence: Insights from pupillometry

PSYCHOPHYSIOLOGY, Issue 1 2010
Elke Van Der Meer
Abstract Thinking is biological work and involves the allocation of cognitive resources. The aim of this study was to investigate the impact of fluid intelligence on the allocation of cognitive resources while one is processing low-level and high-level cognitive tasks. Individuals with high versus average fluid intelligence performed low-level choice reaction time tasks and high-level geometric analogy tasks. We combined behavioral measures to examine speed and accuracy of processing with pupillary measures that indicate resource allocation. Individuals with high fluid intelligence processed the low-level choice reaction time tasks faster than normal controls. The task-evoked pupillary responses did not differ between groups. Furthermore, individuals with high fluid intelligence processed the high-level geometric analogies faster, more accurately, and showed greater pupil dilations than normal controls. This was only true, however, for the most difficult analogy tasks. In addition, individuals with high fluid intelligence showed greater preexperimental pupil baseline diameters than normal controls. These results indicate that individuals with high fluid intelligence have more resources available and thus can solve more demanding tasks. Moreover, high fluid intelligence appears to be accompanied by more task-free exploration. [source]


Interfirm Innovation under Uncertainty: Empirical Evidence for Strategic Knowledge Partitioning,

THE JOURNAL OF PRODUCT INNOVATION MANAGEMENT, Issue 5 2008
Jaegul Lee
This paper analyzes how uncertainty and life-cycle effects condition the knowledge boundary between assemblers and suppliers in interfirm product development. Patents associated with automotive emission control technologies for both assemblers and suppliers are categorized as architectural or component innovations, and technology-forcing regulations imposed by the government on the auto industry from 1970 to 1998 are used to define periods of high and low uncertainty. Results confirm that suppliers dominate component innovation whereas assemblers lead on architectural innovation. More importantly, when facing uncertainty firms adjust their knowledge boundary by increasing the knowledge overlap with their supply-chain collaborators. Suppliers clearly expand their knowledge base relatively more into architectural knowledge during such periods. But assemblers' greater emphasis on component innovation in periods of greater uncertainty is only true as a relative deviation from an overall trend toward increasing component innovation over time. This trend results from an observed life-cycle effect, whereby architectural innovation dominates before the emergence of a dominant design, with component innovation taking the lead afterward. Thus, for assemblers life-cycle effects may dominate over task uncertainty in determining relative effort in component versus architectural innovation. This work extends research on strategic interfirm knowledge partitioning as well as on the information-processing view of product development. First, it provides a large-scale empirical justification for the claim that firms' knowledge boundaries need to extend beyond their task boundaries. Further, it implies that overlaps in knowledge domains between an assembler and suppliers are particularly important for projects involving new technologies. Second, it offers a dynamic view of knowledge partitioning, showing how architectural knowledge prevails in the early phase of the product life cycle whereas component knowledge dominates the later stages. Yet the importance of life-cycle effects versus task uncertainty in conditioning knowledge boundaries is different for assemblers and suppliers, with the former dominating for assemblers and the latter more influential for suppliers. Finally, it supports the idea that architectural and component knowledge are critical elements in the alignment of cognitive frameworks between assemblers and suppliers and thus are key for information-exchange effectiveness and resolution of task uncertainties in interfirm innovation. [source]


Gut passage effect of the introduced red-whiskered bulbul (Pycnonotus jocosus) on germination of invasive plant species in Mauritius

AUSTRAL ECOLOGY, Issue 3 2009
JANNIE F. LINNEBJERG
Abstract In Mauritius, many of the worst invasive plant species have fleshy fruits and rely on animals for dispersal. The introduced red-whiskered bulbul (Pycnonotus jocosus) feeds on many fleshy-fruited species, and often moves from invaded and degraded habitats into higher quality native forests, thus potentially acting as a mediator of continued plant invasion into these areas. Furthermore, gut passage may influence seed germination. To investigate this, we fed fleshy fruits of two invasive plant species, Ligustrum robustum and Clidemia hirta, to red-whiskered bulbuls. Gut passage times of seeds were recorded. Gut-passed seeds were sown and their germination rate and germination success compared with that of hand-cleaned seeds, as well as that of seeds in whole fruits. Gut passage and hand-cleaning had significant positive effects on germination of both species. Gut-passed seeds of both C. hirta and L. robustum germinated faster than hand-cleaned seeds. However, for L. robustum, this was only true when compared with hand-cleaned seeds with intact endocarp; when compared with hand-cleaned seeds without endocarp, there was no difference. For overall germination success, there was a positive effect of gut passage for C. hirta, but not for L. robustum. For both C. hirta and L. robustum, no seeds in intact fruits geminated, suggesting that removal of pulp is essential for germination. Our results suggest that, first, the initial invasion of native forests in Mauritius may not have happened so rapidly without efficient avian seed dispersers like the red-whiskered bulbul. Second, the bulbul is likely to be a major factor in the continued re-invasion of C. hirta and L. robustum into weeded and restored conservation management areas. [source]