994 resultados para explanations


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Games are enjoyable, and research shows that learning to play games can boost learning. Many games use mathematical processes and strategies; this book outlines the context for using mathematics games in classrooms to promote active mathematics learning, curiosity and engaged thinking. There are suggestions for suitable commercially available games and explanations of the rules for card games, dominoes, alphabet games, dice games, drawing games and others. Ways of making a new game, or modifying an existing game are explored, and there are scores of ideas for using games to support mathematical concepts while having fun.

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Migrants, such as birds or representatives of other taxa, usually make use of several stopover sites to cover the distance between their site of origin and destination. Potentially, multiple routes exist, but often little is known about the causes and consequences of alternative migration routes. Apart from their geographical distribution, the suitability of potential sites might play an important role in the animals’ decisions for a particular itinerary. We used an optimal-migration model to test three nonmutually exclusive hypotheses leading to variations in the spring migration routes of a subspecies of Red Knot, Calidris canutus islandica, which migrates from wintering grounds in Western Europe to breeding grounds in Greenland and the Canadian Arctic: the breeding location hypothesis, the energy budget hypothesis, and the predation risk hypothesis. Varying only breeding location, the model predicted that birds breeding in the Canadian Arctic and on West Greenland stop over on Iceland, whereas birds breeding in East and Northeast Greenland migrate via northern Norway, a prediction that is supported by empirical findings. Energy budgets on stopover sites had a strong influence on the choice of route and staging times. Varying foraging-intensity and mass-dependent predation risk prompted the birds to use less risky sites, if possible. The effect of simultaneous changes in the energy budget and predation risk strongly depended on the site where these occurred. Our findings provide potential explanations for the observations that C. canutus islandica uses a diverse array of migration routes. Scrutinizing the three alternative driving forces for the choice of migratory routes awaits further, specific data collection in rapidly developing fields of research (e.g., predation risk assessment, GPS tracking). Generally, the type of modeling presented here may not only highlight alternative explanations, but also direct follow-up empirical research.

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ASA theory is one of the most important explanations of behaviour in organisations. Developed by Professor Ben Schneider, it is the idea that organisations contain similar types of people because they attract, select and retain people similar to those already employed by the organisation. This homogeneity explains why organisations are different to each other. Although a lot is known about attrition, little is known about the attraction and selection phases. This book contains a series of empirical studies that explore whether organisations attract and select people who hold the values of the people already employed by the organisation. The results of these studies cast doubt on how universal ASA theory might be and suggest that the initial employment decisions that people make are more about choosing their vocation than their employer.

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Baylis (1982, Acoustic Communication in Birds, Academic Press) decried the serious lack of experimental verification for the various hypotheses proposed to explain vocal mimicry in songbirds. With few exceptions, our understanding of the function and acquisition of this fascinating behaviour seems to have scarcely progressed. We examine the proposed functional explanations and supporting evidence, and summarize advances made since Baylis's (1982) review. We conclude that there is no compelling evidence to support any of the functional hypotheses but, rather, that almost all of the data concerning song mimicry are consistent with the learning mistakes hypothesis, whereby birds learn simple and common sounds, frequently using them in inappropriate contexts. Additionally, many apparently mimicked sounds are calls, not songs, which themselves may not be learned by the models. It is plausible that many examples of call mimicry are, in fact, due to evolutionary convergence.

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Ubiquitous and mobile computing has increased the level of social connectedness. In an era where technology has permeated into spaces of work, play and socializing, social influence has become an important consideration. The operationalization of the social influence construct in the technology adoption and use literature often assumes singular technology use contexts and purposes. We question whether social influence, as operationalized in IS, is reflective of the utilitarian, hedonic and social environment that many individuals operate in. We propose a framework to consider social influence more inclusively, drawing on differences in referent power and levels of expertise. We outline our research approach within the demographic segment of young working professionals. Research in this area is necessary to improve theoretical explanations of adoptive behavior of these technologies. We hope to contribute by suggesting a richer, more encompassing operationalization of the social influence construct for future IS research.

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The evolutionary relationships of the eutherian order Insectivora (Lipotyphla sensu stricto) are the subject of considerable debate. The difficulties in establishing insectivore phylogeny stem from their lack of many shared derived characteristics. The grouping is therefore something of a ‘wastebasket ’ taxon. Most of the older estimates of phylogeny, based on morphological evidence, assumed insectivore monophyly. More recently, molecular phylogenies argue strongly against monophyly, although they differ in the extent of polyphyly inferred for the order. I review the history of insectivore phylogenetics and systematics, focussing on the relationships between the six extant families (Erinaceidae – hedgehogs and moonrats, Talpidae – moles and desmans, Soricidae – shrews, Solenodontidae – solenodons, Tenrecidae – tenrecs and otter-shrews and Chrysochloridae – golden moles). I then examine how these various phylogenetic hypotheses influence the results of comparative analyses and our interpretation of insectivore life-history evolution. I assess which particular controversies have the greatest effect on results, and discuss the implications for comparative analyses where the phylogeny is controversial. I also explore and suggest explanations for certain insectivore life-history trends : increased gestation length and litter size in tenrecs, increased encephalization in moles, and the mixed fast and slow life-history strategies in solenodons. Finally, I consider the implications for comparative analyses of the recent strongly supported phylogenetic hypothesis of an endemic African clade of mammals that includes the insectivore families of tenrecs and golden moles.

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Using automated and manual radio-telemetry and resightings of individual colour-ringed birds, we assessed the daily use of space of red knots Calidris canutus canutus at a tropical wintering area along the Sahara coast, the Banc d Arguin in Mauritania. Confirming earlier suggestions, we found that birds were very faithful to their roosts and that the daily foraging range was small; in the course of several winter months birds used an area of only 2 16 km2 of intertidal area. We found no differences between their movements in daylight and at night. Additionally, individuals seem to return to exactly the same locations in subsequent winters. This pattern is very different from red knots wintering in the temperate Wadden Sea. Here, they readily change roost sites and easily cover areas of about 800 km2 in the course of weeks but, just as in Mauritania, no differences between day and night are apparent. In northern Patagonia and north-western Australia, red knots have range sizes closer to those on the Banc d Arguin, but here they do show differences in space use between day and night. Ecological explanations for these contrasting patterns require further comparative data based on in-depth studies on the predictability of the food base and the presence of diurnal and nocturnal predators.

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In advanced capitalist societies, intellectual property laws protecting such subject matter as copyright and patents are justified by a combination of theories, which include the provision of economic incentives to foster creativity and innovation and the prevention of unfair competition. IP academics and policy makers have differing views about the appropriate balance between these objectives and public interest considerations such as health, education and the protection of the environment. These different views entered the policy debate in Asian developing countries in connection with an unprecedented introduction and expansion of IP laws over the last 25 years. This paper will use case studies of law reform from Asia, in particular Southeast Asia, to show that the policy considerations of governments in reforming their laws were often quite different from the standard rationale mentioned above. As much of the IP was, at least initially, held by foreigners and introduced to attract foreign investment, national development considerations were joined with the more commonly quoted objectives to promote the rights, creativity and innovation of individuals. Such national development objectives at times coincided and at other times collided with official explanations and received wisdom about the effects of stronger IP rights.

Especially in the early postcolonial period, copyright laws and other IP laws were frequently restricted or simply not implemented, if they conflicted with development policies in areas such as education or public health. Such policies were slowly changing in the wake of WTO-TRIPS and other international agreements. Nevertheless, the implementation and enforcement of the IP laws has been uneven. Specialised institutions such as courts and IP administering agencies compete with other branches of government and administration for limited funding and a rich repertoire of informal dispute settlement procedures has kept the number of court cases relatively low. In some countries, censorship laws have influenced freedom of expression and led to quite idiosyncratic interpretations of intellectual property laws. Governments often also retain a role in the assessment of licensing and technology transfer contracts. And while there are many programs to foster individual creativity, in most cases R & D activities are still largely taking place in government institutions and this has influenced the thinking about intellectual property rights and creativity in the context of employment.

The paper uses a few case studies to examine the implementation of IP laws in selected Asian developing countries to point to the quite different institutional setting for IP law reform in comparison to European or American models. It reaches some tentative conclusions as to the likely effects on creativity and innovation under these different circumstances.

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This article examines the efficacy of fiscal policy in Australia, focusing on the relationship between changes in the economy’s consolidated fiscal imbalance and private sector saving over recent decades. We first examine the macroeconomic significance of the offset coefficient between public and private savings, whose size effectively determines the effectiveness of fiscal activism. The approach innovatively suggests that these estimates simultaneously reflect Ricardian and other non-Keynesian explanations of private consumption, such as the lifecycle and permanent income theories. Econometric estimation of the offset coefficient for Australia over the period 1980–2008 yields values between 0.75 and near unity, which imply a small or near-zero fiscal multiplier, and that running budget surpluses to lift national saving is ineffective.

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In this article, the difficulties some Australian university students experience in academic learning environments are explored. Particular attention is given to the experiences of students whose difficulties are often portrayed as intrinsic to them, and who are diagnosed as having learning disabilities or 'disorders'. In so doing, dominant neuro-psychological perspectives on students' learning 'problems' are challenged, broadening the discussion to include sociocultural explanations of students' difficulties. Research that foregrounds these students' own accounts of their problems is reported, identifying a number of tests of time, association and dissimulation that they experience in coming to terms with the particular institutional requirements of university life. At the very least, these explanations draw attention to the need for university teaching scholars to also be learners, and to consider their own practices in the construction of learning difficulties for their students.

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International studies indicate temporary agency workers are more likely to be injured at work than other types of employees. However explanations for this have been less forthcoming. This paper seeks to begin filling this gap. A study was undertaken in Victoria, Australia, of occupational health and safety (OHS) amongst temporary agency workers drawing upon workers' compensation claim files for injured agency and directly hired workers from 1995-2001, and focus groups of temporary agency workers conducted in 2003. In analyzing the results, use was made of risk factors identified in a model that has been developed to explain how precarious employment affects OHS--the pressure, disorganization and regulatory failure (PDR) model (Quinlan and Bohle, 2004, 2009). Drawing principally on qualitative data, the paper finds that whilst agency workers share common risk factors with other forms of precarious workers, unique characteristics associated with the triangular nature of agency employment heighten their vulnerability further.

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Film thinning experiments have been conducted with aqueous films between two air phases in a thin film pressure balance. The films are free of added surfactant but simple NaCl electrolyte is added in some experiments. Initially the experiments begin with a comparatively large volume of water in a cylindrical capillary tube a few millimeters in diameter, and by withdrawing water from the center of the tube the two bounding menisci are drawn together at a prescribed rate. Thismodels two air bubbles approaching at a controlled speed. In pure water, the results show three regimes of behavior depending on the approach speed; at slow speed (<1 μm/s) it is possible to form a flat film of pure water, ∼100 nm thick, that is stabilized indefinitely by disjoining pressure due to repulsive double-layer interactions between naturally charged air/water interfaces. The data are consistent with a surface potential of -57mV on the bubble surfaces. At intermediate approach speed (∼1-150 μm/s), the films are transiently stable due to hydrodynamic drainage effects, and bubble coalescence is delayed by ∼10-100 s. At approach speeds greater than ∼150 μm/s, the hydrodynamic resistance appears to become negligible, and the bubbles coalesce without any measurable delay. Explanations for these observations are presented that take into account Derjaguin-Landau-Verwey-Overbeek and Marangoni effects entering through disjoining pressure, surface mobility, and hydrodynamic flow regimes in thin film drainage. In particular, it is argued that the dramatic reduction in hydrodynamic resistance is a transition from viscosity-controlled drainage to inertia-controlled drainage associated with a change from immobile to mobile air/water interfaces on increasing the speed of approach of two bubbles. A simple model is developed that accounts for the boundaries between different film stability or coalescence regimes. Predictions of the model are consistent with the data, and the effects of adding electrolyte can be explained. In particular, addition of electrolyte at high concentration inhibits the near-instantaneous coalescence phenomenon, thereby contributing to increased foam film stability at high approach speeds, as reported in previous literature. This work highlights the significance of bubble approach speed as well as electrolyte concentration in affecting bubble coalescence.

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This thesis tested several explanations for the underlying mechanisms of perseveration in populations with ASD. Explanations considered the role of executive dysfunction with particular emphasis on negative feedback, social interaction, and variations in autistic symptomology. The thesis found that negative feedback had the most infiuence on perseveration in ASD populations.

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This paper challenges the assumption within Economics that the relationship between money and subjective wellbeing is determined by processes of cognitive comparison. An alternative explanation for such well known phenomena as the Easterlin Paradox and Decreasing Marginal Utility are provided through a consideration of affect. The theoretical basis for such explanations relies on theory from Psychology usually overlooked by Economists, such as affect heuristics and Subjective Wellbeing Homeostasis. The presented evidence for this alternative source of explanation melds psychological theory with empirical data. It is concluded that affective processes offer a coherent alternative explanation for the phenomena under discussion.

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The males of some species of moths possess elaborate feathery antennae. It is widely assumed that these striking morphological features have evolved through selection for males with greater sensitivity to the female sex pheromone, which is typically released in minute quantities. Accordingly, females of species in which males have elaborate (i.e., pectinate, bipectinate, or quadripectinate) antennae should produce the smallest quantities of pheromone. Alternatively, antennal morphology may be associated with the chemical properties of the pheromone components, with elaborate antennae being associated with pheromones that diffuse more quickly (i.e., have lower molecular weights). Finally, antennal morphology may reflect population structure, with low population abundance selecting for higher sensitivity and hence more elaborate antennae. We conducted a phylogenetic comparative analysis to test these explanations using pheromone chemical data and trapping data for 152 moth species. Elaborate antennae are associated with larger body size (longer forewing length), which suggests a biological cost that smaller moth species cannot bear. Body size is also positively correlated with pheromone titre and negatively correlated with population abundance (estimated by male abundance). Removing the effects of body size revealed no association between the shape of antennae and either pheromone titre, male abundance, or mean molecular weight of the pheromone components. However, among species with elaborate antennae, longer antennae were typically associated with lower male abundances and pheromone compounds with lower molecular weight, suggesting that male distribution and a more rapidly diffusing female sex pheromone may influence the size but not the general shape of male antennae.