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Relative Influence (relative + influence)

Distribution by Scientific Domains

Life Sciences	37%
Humanities and Social Sciences	18%
Earth and Environmental Science	10%
Business, Economics, Finance and Accounting	8%
Psychology	6%
Medical Sciences	6%
Chemistry	3%
4 Other Domains	12%

Selected Abstracts

Relative influence of variables at multiple spatial scales on stream macroinvertebrates in the Northern Lakes and Forest ecoregion, U.S.A.

FRESHWATER BIOLOGY, Issue 8 2003
Brian M. Weigel
Summary 1We used 94 sites within the Northern Lakes and Forests ecoregion spanning Minnesota, Wisconsin and Michigan to identify environmental variables at the catchment, reach and riparian scales that influence stream macroinvertebrates. Redundancy analyses (RDA) found significantly influential variables within each scale and compared their relative importance in structuring macroinvertebrate assemblages. 2Environmental variables included landcover, geology and groundwater delivery estimates at the catchment scale, water chemistry, channel morphology and stream habitat at the reach scale, and landcover influences at three distances perpendicular to the stream at the riparian scale. Macroinvertebrate responses were characterised with 22 assemblage attributes, and the relative abundance and presence/absence of 66 taxa. 3Each scale defined macroinvertebrates along an erosional to depositional gradient. Wisconsin's macroinvertebrate index of biotic integrity, Ephemeroptera,Plecoptera,Trichoptera taxa and erosional taxa corresponded with forest streams, whereas organic pollution tolerant, Chironomidae and depositional taxa corresponded with wetland streams. Reach scale analyses defined the gradient similarly as dissolved oxygen and wide, shallow channels (erosional) opposed instream macrophytes and pool habitats (depositional). Riparian forests within 30 m of the stream coincided with an erosional assemblage and biotic integrity. 4Next, we combined all significant environmental variables across scales to compare the relative influence of each spatial scale on macroinvertebrates. Partial RDA procedures described how much of the explained variance was attributable to each spatial scale and each interrelated scale combination. 5Our results appeared consistent with the concept of hierarchical functioning of scale in which large-scale variables restrict the potential for macroinvertebrate traits or taxa at smaller spatial scales. Catchment and reach variables were equally influential in defining assemblage attributes, whereas the reach scale was more influential in determining relative abundance and presence/absence. 6Ultimately, comprehending the relative influence of catchment and reach scale properties in structuring stream biota will assist prioritising the scale at which to rehabilitate, manage and derive policies for stream ecosystem integrity. [source]

Relative influence of fisheries and climate on the demography of four albatross species

GLOBAL CHANGE BIOLOGY, Issue 7 2010
VIRGINIE ROLLAND
Abstract Worldwide ecosystems are modified by human activities and climate change. To be able to predict future changes, it is necessary to understand their respective role on population dynamics. Among the most threatened species are top predators because of their position in the food web. Albatross populations are potentially affected by both human activities, especially longline fisheries, and climatic fluctuations. Based on long-term data (1985,2006), we conducted through a comparative approach a demographic analysis (adult survival and breeding success) on four albatross species breeding on the Indian Ocean sub-Antarctic Islands to assess the relative impact of climate and fisheries during and outside the breeding season. The study revealed that adult survival of almost all species was not affected by climate, and therefore probably canalized against climatic variations, but was negatively affected by tuna longlining effort in three species. Breeding success was affected by climate, with contrasted effects between species, with Southern Oscillation Index having an impact on all species but one. Differences in demographic responses depended on the foraging zone and season. In order to predict population trajectories of seabirds such as albatrosses, our results show the importance of assessing the relative influence of fishing and climate impacts on demography. [source]

Impact of heat shock on heat shock proteins expression, biological and commercial traits of Bombyx mori

INSECT SCIENCE, Issue 4 2006
VASUDHA B. CHAVADI
Abstract We report the thermotolerance of new bivoltine silkworm, Bombyx mori strains NB4D2, KSO1, NP2, CSR2 and CSR4and differential expression of heat shock proteins at different instars. Different instars of silkworm larva were subjected to heat shock at 35°C, 40°C and 45°C for 2 hours followed by 2 hours recovery. Heat shock proteins were analyzed by SDS-PAGE. The impact of heat shock on commercial traits of cocoons was analyzed by following different strategies in terms of acquired thermotolerance over control. Comparatively NP2 exhibited better survivability than other strains. Resistance to heat shock was increased as larval development proceeds in the order of first instar > second instar > third instar > fourth instar > fifth instar in all silkworm strains. Expression of heat shock proteins varies in different instars. 90 kDa in the first, second and third instars, 84 kDa in the fourth instar and 84, 62, 60, 47 and 33 kDa heat shock proteins in fifth instar was observed in response to heat shock. Relative influence of heat shock on commercial traits that correspond to different stages was significant in all strains. In NB4D2, cocoon and shell weight significantly increased to 17.52% and 19.44% over control respectively. Heat shock proteins as molecular markers for evaluation and evolution of thermotolerant silkworm strains for tropics was discussed. [source]

Relative influence of male and female care in determining nestling mass in a migratory songbird

JOURNAL OF AVIAN BIOLOGY, Issue 5 2010
Kirk W. Stodola
Biparental care is common in birds, with the allocation of effort being highly variable between the sexes. In most songbird species, the female typically provides the most care early in the breeding cycle with both parents providing care when provisioning young. Food provisioning should be directly related to offspring quality; however, the relative influence each parent has on offspring quality has rarely been assessed at the nest level. Consequently, we were interested in assessing the relative influence male and female provisioning has on one measurement of offspring quality, nestling mass, in the black-throated blue warbler Dendroica caerulescens. Over a six year period, 2003,2008, we collected information on average nestling mass per brood on day 6 of the nestling cycle and parental provisioning rates on day 7 of the nestling cycle from 182 first brood nests on three different study plots. We found that average nestling mass was directly related to male provisioning rate, while it was not related to female provisioning rate. On the other hand, estimated biomass provisioned had little influence on average nestling mass, calling into question its utility in assessing parental quality. Finally, there was some indication that parental influence on average nestling mass was dependent on the other parent's provisioning rate, suggesting that parents work in concert to influence nestling quality. [source]

Relative influences of catchment- and reach-scale abiotic factors on freshwater fish communities in rivers of northeastern Mesoamerica

ECOLOGY OF FRESHWATER FISH, Issue 3 2010
P. C. Esselman
Esselman PC, Allan JD. Relative influences of catchment- and reach-scale abiotic factors on freshwater fish communities in rivers of northeastern Mesoamerica. Ecology of Freshwater Fish 2010: 19: 439,454. © 2010 John Wiley & Sons A/S Abstract,,, While the abiotic factors important to freshwater fish assemblages at a reach scale are well understood, studies of larger scale constraints have yielded variable conclusions, spurring a need for further studies in new biogeographic contexts. This study investigated the importance of catchment- and reach-scale abiotic factors to variation in freshwater fish assemblages in rivers of northeastern Mesoamerica. Abiotic variables and fish data from 72 sampling sites on main stem rivers of Belize were used with partial constrained ordination to determine the proportion of spatially structured and unstructured variation in fish presence and absence, relative abundance, and community metrics explained by catchment- and reach-scale environmental factors. Results showed that, combined, catchment and reach variables explained a large portion of the total variation in the fish assemblage data (54,75%), and that catchment environment explained a greater portion of variation (42,63%) than reach environment (34,50%). Variables representing landscape position (local elevation, watershed area) and their reach-level correlates (channel width, depth variation, and substrate) correlated strongly to the fish assemblage data. Our results suggest that landscape-scale factors have a stronger relative influence on assemblages than environmental conditions at the reach scale within our study area. These results contrast with past findings that showed greater local scale influence in landscapes with low anthropogenic disturbance levels. Our findings suggest that biodiversity conservation efforts should consider assemblage variation across a longitudinal gradient, and that a multi-catchment region is a biologically relevant scale for fish conservation planning and coordination in northeastern Mesoamerica. [source]

Human Vulnerability, Dislocation and Resettlement: Adaptation Processes of River-bank Erosion-induced Displacees in Bangladesh

DISASTERS, Issue 1 2004
David Mutton
The purpose of this research was to identify and analyse patterns of economic and social adaptation among river-bank erosion-induced displacees in Bangladesh. It was hypothesised that the role of social demographic and socio-economic variables in determining the coping ability and recovery of the river-bank erosion-induced displacees is quite significant. The findings of the research reveal that displacees experience substantial socio-economic impoverishment and marginalisation as a consequence of involuntary migration. This in part is a socially constructed process, reflecting inequitable access to land and other resources. Vulnerability to disasters is further heightened by a number of identifiable social and demographic factors including gender, education and age, although extreme poverty and marginalisation create complexity to isolate the relative influence of these variables. The need to integrate hazard analysis and mitigation with the broader economic and social context is discussed. It is argued that the capacity of people to respond to environmental threats is a function of not only the physical forces which affect them, but also of underlying economic and social relationships which increase human vulnerability to risk. Hazard analysis and mitigation can be more effective when it takes into account such social and demographic and socio-economic dimensions of disasters. [source]

Relative influences of catchment- and reach-scale abiotic factors on freshwater fish communities in rivers of northeastern Mesoamerica

Foraging for Work and Age-Based Polyethism: The Roles of Age and Previous Experience on Task Choice in Ants

ETHOLOGY, Issue 11 2004
Frederic Tripet
In social insects, colonies commonly show temporal polyethism in worker behavior, such that a worker follows a predictable pattern of changes between tasks as it ages. This pattern usually leads from workers first doing a safe task like brood care, to ending their lives doing the most dangerous tasks like foraging. Two mechanisms could potentially underlie this pattern: (1) age-based task allocation, where the aging process itself predisposes workers to switch to more dangerous tasks; and (2) foraging for work, where ants switch to tasks that need doing from tasks which have too many associated workers. We tested the relative influence of these mechanisms by establishing nests of Camponotus floridanus with predetermined combinations of workers of known age and previous task specialization. The results supported both mechanisms. Nests composed of entirely brood-tending workers had the oldest workers preferentially switching to foraging. However, in nests initially composed entirely of foragers, the final distribution of tenders and foragers was not different from random task-switching and therefore supportive of foraging for work. Thus, it appears that in C. floridanus there is directionality to the mechanisms of task allocation. Switching to more dangerous tasks is age-influenced, but switching to less dangerous tasks is age-independent. The results also suggest that older workers are more flexible in their task choice behavior. Younger workers are more biased towards choosing within-nest tasks. Finally, there are effects of previous experience that tend to keep ants in familiar tasks. Task allocation based on several mechanisms may balance between: (1) concentrating the most worn workers into the most dangerous tasks; (2) increasing task performance levels; and (3) maintaining behavioral flexibility to respond to demographic perturbations. The degree to which behavior is flexible may correlate to the frequency of such perturbations in a species. [source]

Aspects of cleavage fracture initiation , relative influence of stress and strain

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 9-10 2006
K. WALLIN
ABSTRACT Cleavage fracture initiation has generally been assumed to be controlled mainly by matrix stress. Recently, several different cleavage fracture models have been proposed, where also strain is included in the failure criterion. However, the proposals have been rather crude and unable to provide clearly improved fracture estimates. Here, the first two steps of cleavage fracture (particle failure and grain fracture) are examined in more detail. It is shown that both stress and strain are important for cleavage fracture initiation, but that strain mainly affects particle failure, whereas grain fracture is controlled by a pure Griffith criterion. The findings are important for the development of new cleavage fracture models and to the proper way of accounting for constraint. [source]

Hydrologic versus geomorphic limitation on CPOM storage in stream ecosystems

FRESHWATER BIOLOGY, Issue 8 2008
MELANIE J. SMALL
Summary 1. Stream ecosystems are the products of interactions between hydrology, geomorphology and ecology, but examining all three components simultaneously is difficult and rarely attempted. Frequently, either geomorphology or hydrology is treated as invariable or static. 2. To examine the validity of treating either hydrology or geomorphology as static, we studied the individual and combined effects of hydrology and channel geomorphology on coarse particulate organic matter (CPOM) storage. Using data from an experimental leaf release in a hydrologically regulated stream we created a simple numerical model. This allowed us to quantify the relative influence of CPOM trapping and CPOM retention on total long-term CPOM storage under variable regimes of flood frequency and geomorphic structure. 3. CPOM storage is a function of supply, flood frequency and the type and frequency of in-stream structures. In-stream structures perform two distinct functions, trapping and retention, whose relative importance in leaf storage changes with stream hydrology. Trapping is more important for CPOM storage in streams with few floods, while retention is more important in streams with frequent floods. Different structures (e.g. boulders, large wood, small wood) perform these functions at different efficiencies. We found that large wood trapped two to three times more leaves than the bank, but that the bank retained leaves two to three times more efficiently. 4. A modelled channel with five times the amount of large wood as the study channel (a ,wood restoration') initially stored 14% more leaves than the modelled ,natural' channel. After six floods, however, the modelled wood restoration channel stored 50% less CPOM than the natural channel as the large wood had high trapping but poor retention. The modelled natural channel contained structures that could both trap and retain. Thus, as different structures performed different functions, the structural complexity buffered the stream allochthonous energy base against changes in hydrology through its balance of trapping and retention. 5. As the frequency of floods increased, the spatial distribution of CPOM became increasingly patchy as storage was driven entirely by structures with high retention. Thus, the coupling of flood frequency and geomorphic structure influenced CPOM availability, which in turn has ramifications for the entire stream food web. [source]

Invertebrate community structure in streams of the Manawatu,Wanganui region, New Zealand: the roles of catchment versus reach scale influences

FRESHWATER BIOLOGY, Issue 8 2004
Russell G. Death
Summary 1. Invertebrate communities at 187 least impacted streams in the Manawatu,Wanganui region of New Zealand were sampled between February and May 2000 to investigate the relative influence of catchment and reach scale environmental influences on community structure. 2. Of the 138 biological (fish and periphyton), local habitat and catchment scale descriptors used to examine invertebrate community patterns, alkalinity and conductivity were the most consistently influential predictors. 3. Of the 52 geographical information system (GIS)-derived catchment variables (catchment geology, catchment land use, rainfall and topography) only per cent catchment in pasture, indigenous forest, coastal sand, crushed argillite and wind blown sand were associated with any measures of the invertebrate communities. 4. Grouping of communities based on GIS data in general, did not generate distinct community types. Groupings based on river catchment, conductivity and alkalinity however, did produce distinct communities. 5. Streams with very low alkalinity were dominated by Ephemeroptera, Plecoptera and Trichoptera that were gradually replaced by Mollusca, Crustacea and Chironomidae as alkalinity increases. 6. Habitat characteristics measured at the scale of the reach were more closely linked with measures of invertebrate community structure than any GIS derived variables or river classifications. [source]

Relative influence of variables at multiple spatial scales on stream macroinvertebrates in the Northern Lakes and Forest ecoregion, U.S.A.

A comparison of cross-hole electrical and seismic data in fractured rock

GEOPHYSICAL PROSPECTING, Issue 2 2004
J.V. Herwanger
ABSTRACT Cross-hole anisotropic electrical and seismic tomograms of fractured metamorphic rock have been obtained at a test site where extensive hydrological data were available. A strong correlation between electrical resistivity anisotropy and seismic compressional-wave velocity anisotropy has been observed. Analysis of core samples from the site reveal that the shale-rich rocks have fabric-related average velocity anisotropy of between 10% and 30%. The cross-hole seismic data are consistent with these values, indicating that observed anisotropy might be principally due to the inherent rock fabric rather than to the aligned sets of open fractures. One region with velocity anisotropy greater than 30% has been modelled as aligned open fractures within an anisotropic rock matrix and this model is consistent with available fracture density and hydraulic transmissivity data from the boreholes and the cross-hole resistivity tomography data. However, in general the study highlights the uncertainties that can arise, due to the relative influence of rock fabric and fluid-filled fractures, when using geophysical techniques for hydrological investigations. [source]

Relative influence of fisheries and climate on the demography of four albatross species

Body size-dependent responses of a marine fish assemblage to climate change and fishing over a century-long scale

GLOBAL CHANGE BIOLOGY, Issue 2 2010
MARTIN J. GENNER
Abstract Commercial fishing and climate change have influenced the composition of marine fish assemblages worldwide, but we require a better understanding of their relative influence on long-term changes in species abundance and body-size distributions. In this study, we investigated long-term (1911,2007) variability within a demersal fish assemblage in the western English Channel. The region has been subject to commercial fisheries throughout most of the past century, and has undergone interannual changes in sea temperature of over 2.0 °C. We focussed on a core 30 species that comprised 99% of total individuals sampled in the assemblage. Analyses showed that temporal trends in the abundance of smaller multispecies size classes followed thermal regime changes, but that there were persistent declines in abundance of larger size classes. Consistent with these results, larger-growing individual species had the greatest declines in body size, and the most constant declines in abundance, while abundance changes of smaller-growing species were more closely linked to preceding sea temperatures. Together these analyses are suggestive of dichotomous size-dependent responses of species to long-term climate change and commercial fishing over a century scale. Small species had rapid responses to the prevailing thermal environment, suggesting their life history traits predisposed populations to respond quickly to changing climates. Larger species declined in abundance and size, reflecting expectations from sustained size-selective overharvesting. These results demonstrate the importance of considering species traits when developing indicators of human and climatic impacts on marine fauna. [source]

Litter decomposition in grasslands of Central North America (US Great Plains)

GLOBAL CHANGE BIOLOGY, Issue 5 2009
ELIANA E. BONTTI
Abstract One of the major concerns about global warming is the potential for an increase in decomposition and soil respiration rates, increasing CO2 emissions and creating a positive feedback between global warming and soil respiration. This is particularly important in ecosystems with large belowground biomass, such as grasslands where over 90% of the carbon is allocated belowground. A better understanding of the relative influence of climate and litter quality on litter decomposition is needed to predict these changes accurately in grasslands. The Long-Term Intersite Decomposition Experiment Team (LIDET) dataset was used to evaluate the influence of climatic variables (temperature, precipitation, actual evapotranspiration, and climate decomposition index), and litter quality (lignin content, carbon : nitrogen, and lignin : nitrogen ratios) on leaf and root decomposition in the US Great Plains. Wooden dowels were used to provide a homogeneous litter quality to evaluate the relative importance of above and belowground environments on decomposition. Contrary to expectations, temperature did not explain variation in root and leaf decomposition, whereas precipitation partially explained variation in root decomposition. Percent lignin was the best predictor of leaf and root decomposition. It also explained most variation in root decomposition in models which combined litter quality and climatic variables. Despite the lack of relationship between temperature and root decomposition, temperature could indirectly affect root decomposition through decreased litter quality and increased water deficits. These results suggest that carbon flux from root decomposition in grasslands would increase, as result of increasing temperature, only if precipitation is not limiting. However, where precipitation is limiting, increased temperature would decrease root decomposition, thus likely increasing carbon storage in grasslands. Under homogeneous litter quality, belowground decomposition was faster than aboveground and was best predicted by mean annual precipitation, which also suggests that the high moisture in soil accelerates decomposition belowground. [source]

Threshold response of Madagascar's littoral forest to sea-level rise

GLOBAL ECOLOGY, Issue 1 2009
Malika Virah-Sawmy
ABSTRACT Aim, Coastal biodiversity hotspots are globally threatened by sea-level rise. As such it is important to understand how ecosystems resist, respond and adapt to sea-level rise. Using pollen, geochemistry, charcoal and diatom records in conjunction with previously published palaeoclimatic records, we investigated the mechanism, interactions and ecosystem response and resilience of Madagascar's littoral forest to late Holocene sea-level rise. Location, Sediment sequences were collected along the south-east coast of Madagascar in two adjacent habitats in Mandena; the highly diverse littoral forest fragment and species-poor Erica -matrix. Methods, We used a multi-proxy approach to investigate the relative influence of environmental changes on the littoral ecosystem. We reconstructed past vegetation and fire dynamics over the past 6500 years at two sites in the littoral forest using fossil pollen and macrofossil charcoal contained in sedimentary sequences. Alongside these records we reconstructed past marine transgressions from the same sedimentary sequences using geochemical analyses, and a salinity and drought index through the analysis of fossil diatoms. Results, Our findings indicated that it was the synergistic effect of sea-level rise coupled with rainfall deficits that triggered a threshold event with a switch from two types of littoral forest (an open Uapaca forest and a closed littoral forest fragment) to an Erica,Myrica heath/grassland occurring in approximately less than 100 years. Resilience to sea-level rise differed in the two adjacent habitats, suggesting that the littoral forest fragment was more resilient to the impacts of sea-level change and aridity than the open Uapaca woodland. Conclusions, We demonstrated that the littoral ecosystem was influenced by late Holocene sea-level rise and climatic desiccation. While climate change-integrated conservation strategies address the effects of climate change on species distribution and dispersal, our work suggests that more attention should be paid to the impacts of interactive climatic variables that affect ecosystem thresholds. [source]

Ideas, Interests, and Institutions: Challenging the Property Rights Paradigm in Botswana

GOVERNANCE, Issue 4 2003
Amy R. Poteete
Recent work in international studies and comparative politics scrutinizes the relative importance of ideas, interests, and institutions as sources of policy change. A growing body of scholarship identifies ideas as the main causal factors, influencing perceived interests as well as perceived policy options. Others contend that policies can best be understood as products of institutions. Neither explanation can account for both policy choice by politicians and the implementation strategies of administrators. In Botswana, the use of professional criteria for hiring and advancement encourages adherence to international professional norms within the bureaucracy, but electoral competition gives politicians more reason to be attentive to local political concerns. The institutions that define relations of authority among actors with different motivations shape the outcomes of policy choice and implementation. Institutions influence the attentiveness of policy-makers to ideas when making decisions, the degree of attention particular policy-makers give to ideas from particular sources, and the degree of acceptance that ideas must achieve to affect policy. Better evaluations of political development can be achieved through attentiveness to the mix of actors involved in policy decisions, the diversity of institutions and ideas that affect their policy preferences, and the relations of authority that shape their relative influence over policy choice and implementation. [source]

Observing Purchase-Related Parent,Child Communication in Retail Environments: A Developmental and Socialization Perspective

HUMAN COMMUNICATION RESEARCH, Issue 1 2008
Moniek Buijzen
In a quantitative observation study, we unobtrusively examined purchase-related communication between 0- to 12-year-old children and their parents (N= 269 dyads) during supermarket and toy store visits. The aims of the study were to determine (a) the development of purchase-related parent,child communication (i.e., children's purchase influence attempts, their coercive behavior, parent-initiated communication) and (b) the relative influence of different socialization variables (e.g., television viewing, family communication patterns) on these communication variables. Our inverted-U hypothesis for the effect of developmental level on purchase influence attempts received support: Children's purchase influence attempts increased until early elementary school and started to decline in late elementary school. Our inverted-U hypothesis for the effect of developmental level on coercive behavior was also supported: Children's coercive behavior was highest among preschoolers. With increasing age, children were more likely to be involved in the purchase decision-making process, and parent,child communication more often resulted in a product purchase. Finally, children's television viewing was the most important (positive) predictor of their purchase influence attempts. Résumé L'observation dans des environnements commerciaux de la communication parent-enfant liée à l,achat: Une perspective du développement et de la socialisation Dans une étude quantitative par observation, nous avons discrètement examiné la communication liée à l'achat entre des enfants de 0 à 12 ans et leurs parents (N= 269 dyades) au cours de visites dans des supermarchés et des boutiques de jouets. Les objectifs de l'étude étaient de déterminer a) le développement de la communication parent-enfant liée à l,achat (c.-à-d. les tentatives des enfants d'influencer l,achat, leur comportement coercitif ainsi que la communication initiée par le parent) et b) l'influence relative de différentes variables de socialisation (par exemple l'écoute de la télévision ou les schémas de communication familiaux) sur ces variables communicationnelles. Notre hypothèse en U inversé concernant l,effet du niveau de développement sur les tentatives d'influence d,achat fut appuyée : les tentatives des enfants d'influencer les achats ont augmenté jusqu,au début de l'école élémentaire et ont commencéà décliner à la fin de l'école élémentaire. Notre hypothèse en U inversé supposant des effets du niveau de développement sur le comportement coercitif fut aussi appuyée : le comportement coercitif fut le plus élevé chez les enfants d'âge préscolaire. Plus l'âge augmentait et plus les enfants étaient susceptibles d'être impliqués dans le processus décisionnel d'achat, et la communication parent-enfant résultait plus souvent en l,achat d'un produit. Finalement, l'écoute télévisuelle des enfants était la variable explicative (positive) la plus importante de leurs tentatives d,influence des achats. Abstract Beobachtung von kaufbezogener Elternteil-Kind-Kommunikation in Einzelhandelsumgebungen: Eine Entwicklungs- und Sozialisationsperspektive In einer quantitativen Beobachtungsstudie untersuchten wir verdeckt die kaufbezogene Kommunikation zwischen Kindern (0-12 Jahre) und einem Elternteil (N=269 Dyaden) während ihres Besuchs im Supermarkt oder Spielzeugladen. Ziele der Studie waren: a) die Entwicklung von kaufbezogener Kommunikation zwischen Elternteil und Kind und b) den relativen Einfluss verschiedener Sozialisationsvariablen (z.B. Fernsehnutzung, Familienkommunikationsmuster) auf diese Variablen zu untersuchen. Unsere umgekehrte U-Hypothese bezüglich des Einflusses des Entwicklungsstadiums auf den Grad der Einflussnahmeversuche auf den Kauf wurde gestützt: Die Einflussnahmeversuche nahmen bis zur frühen Grundschulzeit zu und gingen in der späten Grundschulzeit zurück. Unsere umgekehrte U-Hypothese bezüglich des Einflusses des Entwicklungsstadiums auf erzwingendes Verhalten wurde auch bestätigt: erzwingendes Verhalten von Kindern war am stärksten im Vorschulalter. Mit zunehmendem Alter wurden Kinder mehr in Kaufentscheidungsprozesse einbezogenen und die Eltern-Kind-Kommunikation resultierte häufiger im Kauf des Produkts. Letztendlich zeigte sich, dass das Fernsehnutzungsverhalten der Kinder der wichtigste (positive) Prädiktor für Kaufeinflussversuche war. Resumen Observando la Comunicación entre Padres y Niños durante las Compras en los Ambientes de Venta al por Menor: Una Perspectiva de Desarrollo y Socialización En un estudio de observación cuantitativa, examinamos de manera discreta la comunicación relacionada con la compra entre niños de 0- a 12-anos de edad y sus padres (N= 269 dúos) durante sus visitas al supermercado y las tiendas de juguetes. Los propósitos de este estudio fueron determinar (a) el desarrollo de la comunicación entre padres e hijos durante las compras (a saber, los intentos de los niños de influir en la compra, el comportamiento coercitivo, la comunicación iniciada por los padres), y (b) la influencia relativa de las diferentes variables de socialización (a saber, exposición a la televisión, pautas de comunicación familiar) sobre estas variables de comunicación. Nuestra hipótesis U invertida para los efectos del nivel de desarrollo sobre los intentos de influencia de compra recibieron apoyo: Los intentos de los niños de influir en la compra incrementaron hasta antes de la escuela primaria y comenzó a declinar más tarde en la escuela primaria. Nuestra hipótesis U invertida para los efectos del nivel de desarrollo sobre el comportamiento coercitivo recibieron apoyo: El comportamiento coercitivo fue mayor durante la etapa pre-escolar. Con el aumento de la edad, los niños se involucraron más probablemente en el proceso de decisión de compra, y la comunicación padre-hijo resultó más a menudo en la compra de un producto. Finalmente, la exposición de los niños a la televisión fue el vaticinador más importante (positivo) de sus intentos de influencia de compra. ZhaiYao Yo yak [source]

Perception and Politics in Intelligence Assessment: U.S. Estimates of the Soviet and "Rogue-State" Nuclear Threats

INTERNATIONAL STUDIES PERSPECTIVES, Issue 4 2009
James H. Lebovic
United States estimates of Soviet nuclear goals and capabilities and the current "rogue-state" nuclear threat reflected prevailing beliefs about threat within the U.S. government and the relative influence of agencies charged with threat assessment. This article establishes that the patterns in formal Soviet threat assessment: (i) did not reflect a uniform response to "external threat," (ii) were inevitably tied to underlying assumptions about adversary intent, and (iii) were susceptible then to perceptual, organizational, and/or political influences within government. Thus, threat assessments reflected the optimism and pessimism,and political interests and ideologies,of those who participated in the estimating process. The article concludes by examining these lessons in light of the experiences and challenges of assessing threat from small states harboring nuclear ambitions. [source]

An Examination of Established Antecedents of Power in Purchase Decision Making: Married and Nontraditional Couples

JOURNAL OF APPLIED SOCIAL PSYCHOLOGY, Issue 9 2004
Michelle C. Reiss
This research examined the extent that resource theory, sex-role orientation, least interested partner hypothesis, and involvement apply to cohabiting heterosexual, gay, and lesbian couples. Findings revealed that (a) resources significantly affected only married partners' relative influence and strategy usage; (b) sex-role orientation significantly affected relative influence for married partners and strategy selection for partners in both types of heterosexual couples; (c) least interest significantly affected relative influence for partners in both types of heterosexual couples and influence strategy selection for cohabi-tors; and (d) involvement significantly affected relative influence and strategy usage for all couple types. Overall, the effect of the antecedents on relative influence and strategy usage depends on the extent that partners within any couple type are similar on various antecedents. [source]

Relative influence of male and female care in determining nestling mass in a migratory songbird

Simulating the East African wildebeest migration patterns using GIS and remote sensing

AFRICAN JOURNAL OF ECOLOGY, Issue 4 2004
Douglas E. Musiega
Abstract The Serengeti,Mara ecosystem in East Africa is a spectacular natural heritage endowed with diverse fauna and flora. The presence of the seasonally migrating wildebeest (Connochaetes taurinus) is a major boost for tourism. This migration however has enormous impacts to the ecosystem. Consequently efforts at monitoring the herd's migration trends and patterns remain a challenge to wildlife managers and ecologists in the region. In this paper, the relative influence of vegetation (normalized difference vegetation index), landscape and relief on herds migration routes are investigated and the migration routes simulated using GIS and remote sensing techniques. The results are compared with the annual mean route taken by the herds, as determined by radio tracking over the 1995,1997 period. Green vegetation availability is shown to be the major criterion in route choice. It is also shown that during the dry season phases of the migration (western trek, western corridor), the herd endures complex relief (complexity quantified based on slope and inter-visibility) in the search for greener grass. During the season of abundance (southern trek), relief becomes critical in making route choices, with herds avoiding difficult terrain, notwithstanding their relatively more abundant vegetation. The method proposed in this paper is viable for rapid prediction of approximate routes for the migrating wildebeest in different climatic conditions. Résumé L'écosystème Serengeti,Mara en Afrique Occidental est un patrimoine naturel spectaculaire, doté des divers variétés de flore et de faune. La présence du gnou migrateur (Connochaetes taurinus) représente un atout majeur pour le tourisme. Néanmoins, cette migration a un impact énorme sur l'écosystème. Par conséquence, la surveillance des tendances migratoires du troupeau est un défi constant pour les gérants et les écologistes dans la région. Dans cette enquête, l'influence relative de la végétation (NDVI), le paysage et le relief, sur les routes du migration prises par le troupeau ont étéétudiés, et simulés utilisant le Système d'Information Géographique (SIG) et des techniques de perception à distance. Les résultats sont comparés à la moyenne annuelle des routes prises par les troupeaux, déterminée par le repérage radio pendant la période allant de 1995 a 1997. Le disponibilité de végétation verte s'avère le déterminant majeur dans le choix du chemin. Il est aussi démontré que pendant les phases du migration en saison sèche (périple vers l'ouest, couloir vers l'ouest) le troupeau subit des reliefs complexes (complexité calculée sur la pente et inter visibilité) à la recherche de l'herbe la plus verte. Pendant la saison d'abondance (périple vers le sud), l'impact du relief sur le choix des routes devient critique, les troupeaux évitant le terrain difficile, malgré sa végétation relativement abondante. La méthode présentée dans cette étude permet de prédire de façon rapide et valable la route approximative des gnous en cours de migration dans des conditions climatiques diverses. [source]

Materialism as a predictor variable of low income consumer behavior when entering into installment plan agreements

JOURNAL OF CONSUMER BEHAVIOUR, Issue 1 2008
Mateus Canniatti Ponchio
This paper explores the influence of materialism on consumer indebtedness among low income individuals who live in poor regions of Sao Paulo. A materialism scale was adapted to this context and used to describe the level of materialism among the population surveyed. Results obtained relative to the relationship between materialism and socio-demographic variables are compared to those of previous studies. A logistic regression model was developed in order to characterize individuals who have an installment plan payment booklet,the main source of consumer credit for the population studied,and to differentiate them from those who do not, based on the materialism level, socio-demographic variables and purchasing and consumer habits. The proposed model confirms materialism as a behavioral variable that is useful for forecasting the probability of an individual getting into debt in order to consume. Income had the biggest relative influence on the regression model, followed by materialism and age, controlled by gender. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Genetic architecture of population differences in oviposition behaviour of the seed beetle Callosobruchus maculatus

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2004
C. W. Fox
Abstract Few studies have examined the genetic architecture of population differences in behaviour and its implications for population differentiation and adaptation. Even fewer have examined whether differences in genetic architecture depend on the environment in which organisms are reared or tested. We examined the genetic basis of differences in oviposition preference and egg dispersion between Asian (SI) and African (BF) populations of the seed beetle, Callosobruchus maculatus. We reared and tested females on each of two host legumes (cowpea and mung bean). The two populations differed in mean oviposition preference (BF females preferred cowpea seeds more strongly than did SI females) and egg dispersion (SI females distributed eggs more uniformly among seeds than did BF females). Observations of hybrid and backcross individuals indicated that only the population difference in oviposition preference could be explained by complete additivity, whereas substantial dominance and epistasis contributed to the differences in egg dispersion. Both rearing host and test host affected the relative magnitude of population differences in egg dispersion and the composite genetic effects. Our results thus demonstrate that the relative influence of epistasis and dominance on the behaviour of hybrids depends on the behaviour measured and that different aspects of insect oviposition are under different genetic control. In addition, the observed effect of rearing host and oviposition host on the relative importance of dominance and epistasis indicates that the genetic basis of population differences depends on the environment in which genes are expressed. [source]

Population dynamics of cereal aphids: influence of a shared predator and weather

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2009
T. W. Leslie
Abstract 1,Aphid populations may show strong year-to-year fluctuations, but questions remain regarding the dominance of factors that cause this variation, especially the role of natural enemies. To better understand the dynamics of aphid species that occur as pests in cereals, we investigated the relative influence of top-down control by a predator and weather (temperature and precipitation) on population fluctuations of three cereal aphid species. 2,From 1987 to 2005, populations of Metopolophium dirhodum, Sitobion avenae and Rhopalosiphum padi in insecticide-free stands of winter wheat were monitored in the Praha-Ruzyné region of the Czech Republic. Densities of an aphidophagous predator, the ladybeetle Coccinella septempunctata, were recorded from an overwintering site in the landscape. Weather was quantified using historical records. 3,A significant bottom-up effect of densities of aphids on those of C. septempunctata was found, but evidence of direct top-down regulation of aphids by C. septempunctata was only significant in the case of R. padi. There was no significant periodicity in the dynamics of the aphid or C. septempunctata, suggesting that there was no clear predator-prey cycle. Combinations of C. septempunctata and weather variables could be used to explain M. dirhodum and R. padi per capita rate of change. There were also indications that weather directly affected peak density of M. dirhodum. 4,We conclude that regional estimates of C. septempunctata densities are not sufficient to determine whether aphid population dynamics are driven by predator,prey interactions. Feasibility of time series analysis as an investigative tool in aphid population dynamics studies is discussed. [source]

Multivariate and geometric morphometrics in the analysis of sexual dimorphism variation in Podarcis lizards

JOURNAL OF MORPHOLOGY, Issue 2 2007
Antigoni Kaliontzopoulou
Abstract Podarcis bocagei and P. carbonelli are two closely related lacertid species, very similar morphologically and ecologically. We investigated sexual dimorphism patterns presented by both species in allopatry and in sympatry. Sexual size and shape dimorphism patterns were analyzed using both multivariate and geometric morphometric techniques. Multivariate morphometrics revealed a marked sexual dimorphism in both species,males being larger with more robust habitus and females presenting a longer trunk. General patterns of sexual size dimorphism are not modified in sympatry, although there is evidence for some morphological change in male head size. The application of geometric morphometrics offered a more detailed image of head shape and revealed that males present a more developed tympanic area than do females, while females have a more rounded head. Differences in the degree of sexual shape dimorphism were detected in sympatry, but no consistent patterns were observed. From the results of the study, and based on previous knowledge on the populations studied, we conclude that the morphological differences observed are probably not caused by exploitative competition between the species, but rather appear attributable to the modification of the relative influence of sexual and natural selection on both sexes. J. Morphol., 2007. © 2007 Wiley-Liss, Inc. [source]

Soil-aggregate formation as influenced by clay content and organic-matter amendment

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 1 2007
Stephen Wagner
Abstract Naturally occurring wetting-and-drying cycles often enhance aggregation and give rise to a stable soil structure. In comparatively dry regions, such as large areas of Australia, organic-matter (OM) contents in topsoils of arable land are usually small. Therefore, the effects of wetting and drying are almost solely reliant on the clay content. To investigate the relations between wetting-and-drying cycles, aggregation, clay content, and OM in the Australian environment, an experiment was set up to determine the relative influence of both clay content (23%, 31%, 34%, and 38%) and OM amendments of barley straw (equivalent to 3.1,t,ha,1, 6.2,t,ha,1, and 12.4,t,ha,1) on the development of water-stable aggregates in agricultural soil. The aggregate stability of each of the sixteen composite soils was determined after one, three, and six wet/dry cycles and subsequent fast and slow prewetting and was then compared to the aggregate stabilities of all other composite soils. While a single wet/dry cycle initiated soil structural evolution in all composite soils, enhancing macroaggregation, the incorporation of barley straw was most effective for the development of water-stable aggregates in those soils with 34% and 38% clay. Repeated wetting-and-drying events revealed that soil aggregation is primarily based on the clay content of the soil, but that large straw additions also tend to enhance soil aggregation. Relative to untreated soil, straw additions equivalent to 3.1,t,ha,1 and 12.4,t,ha,1 increased soil aggregation by about 100% and 250%, respectively, after three wet/dry cycles and fast prewetting, but were of less influence with subsequent wet/dry cycles. Straw additions were even more effective in aggregating soil when combined with slow prewetting; after three wet/dry cycles, the mean weight diameters of aggregates were increased by 70% and 140% with the same OM additions and by 160% and 290% after six wet/dry cycles, compared to samples without organic amendments. We suggest that in arable soils poor in OM and with a field texture grade of clay loam or finer, the addition of straw, which is often available from preceding crops, may be useful for improving aggregation. For a satisfactory degree of aggregate stability and an improved soil structural form, we found that straw additions of at least 6.2,t,ha,1 were required. However, rapid wetting of straw-amended soil will disrupt newly formed aggregates, and straw has only a limited ability to sustain structural improvement. [source]

Design, validation, and use of an evaluation instrument for monitoring systemic reform

JOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 6 2001
Kathryn Scantlebury
Over the past decade, state and national policymakers have promoted systemic reform as a way to achieve high-quality science education for all students. However, few instruments are available to measure changes in key dimensions relevant to systemic reform such as teaching practices, student attitudes, or home and peer support. Furthermore, Rasch methods of analysis are needed to permit valid comparison of different cohorts of students during different years of a reform effort. This article describes the design, development, validation, and use of an instrument that measures student attitudes and several environment dimensions (standards-based teaching, home support, and peer support) using a three-step process that incorporated expert opinion, factor analysis, and item response theory. The instrument was validated with over 8,000 science and mathematics students, taught by more than 1,000 teachers in over 200 schools as part of a comprehensive assessment of the effectiveness of Ohio's systemic reform initiative. When the new four-factor, 20-item questionnaire was used to explore the relative influence of the class, home, and peer environment on student achievement and attitudes, findings were remarkably consistent across 3 years and different units and methods of analysis. All three environments accounted for unique variance in student attitudes, but only the environment of the class accounted for unique variance in student achievement. However, the class environment (standards-based teaching practices) was the strongest independent predictor of both achievement and attitude, and appreciable amounts of the total variance in attitudes were common to the three environments. © 2001 John Wiley & Sons, Inc. J Res Sci Teach 38: 646,662, 2001 [source]

In vitro bioavailability of calcium and iron from selected green leafy vegetables,

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2006
Sheetal Gupta
Abstract The objective of the present investigation was to analyze the relative influence of oxalic acid, phytic acid, tannin and dietary fiber on in vitro availability of iron and calcium from green leafy vegetables (GLV). Thirteen GLV were selected and analyzed for iron, calcium, oxalic acid, phytic acid, tannin and dietary fiber contents using standard methods. The bioavailability of calcium and iron in the GLV was estimated by equilibrium dialysis. Oxalic acid content was less than 1 g kg,1 in four greens and ranged between 1.22 to 11.98 g kg,1 in the remaining. Dietary fiber ranged from 19.5 to 113.7 g kg,1. Tannin content ranged between 0.6138 and 2.1159 g kg,1 with the exception of two GLV that had 0.1332 and 14.8619 g kg,1. Four GLV were found to have approximately 40% bioavailable iron, while the others were in the range of 6,30%. In vitro available calcium was less than or equal to 25% in eight GLV and between 34% and 52% in five GLV. Multiple regression analysis revealed that these factors together accounted for 53% (r2 = 0.53) and 45% (r2 = 0.45) inhibition of iron and calcium absorption, respectively. These findings infer that calcium and iron availability is influenced by the constituents present in the GLV. Copyright © 2006 Society of Chemical Industry [source]