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Environmental Forces (environmental + force)
Selected AbstractsThe implications of solar UV radiation exposure for fish and fisheriesFISH AND FISHERIES, Issue 3 2001Horacio E Zagarese Abstract Ultraviolet radiation (UVR) possesses three important properties that combine to make it a potent environmental force. These include the potential to induce damage: UVR carries more energy per photon than any other wavelength reaching the Earth's surface. Such highly energetic photons are known to damage many biological molecules, such as DNA and proteins. In addition, they can initiate a series of redox reactions to form reactive oxygen species (ROS), which cause oxidative stress to cells and tissues. The second property is ubiquity: owing to their dependence on light, primary producers and most visual predators, such as fish, are also necessarily exposed to damaging levels of UVR. Thirdly, the combined effect of UVR and additional environmental factors may result in synergistic effects, such as the photoactivation of organic pollutants and photosensitisation. In natural environments, the concentration of dissolved organic matter (DOM) and habitat depth are the two main factors controlling the degree of UVR exposure experienced by fish. Additional factors include vegetation coverage, particulate materials in suspension, pH and hydrological characteristics, and site location (latitude, elevation). The range of potential effects on fish includes direct DNA damage resulting in embryo and larval mortality, and adult and juvenile sunburn, as well as indirect oxidative stress, phototoxicity and photosensitisation. [source] Estimation of environmental force for the haptic interface of robotic surgeryTHE INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY, Issue 2 2010Hyoung Il Son Abstract Background The success of a telerobotic surgery system with haptic feedback requires accurate force-tracking and position-tracking capacity of the slave robot. The two-channel force-position control architecture is widely used in teleoperation systems with haptic feedback for its better force-tracking characteristics and superior position-tracking capacity for the maximum stability margin. This control architecture, however, requires force sensors at the end-effector of the slave robot to measure the environment force. However, it is difficult to attach force sensors to slave robots, mainly due to their large size, insulation issues and also large currents often flowing through the end-effector for incision or cautery of tissues. Methods This paper provides a method to estimate the environment force, using a function parameter matrix and a recursive least-squares method. The estimated force is used to feed back the force information to the surgeon through the control architecture without involving the force sensors. Results The simulation and experimental results verify the efficacy of the proposed method. The force estimation error is negligible and the slave device successfully tracks the position of the master device while the stability of the teleoperation system is maintained. Conclusions The developed method allows practical haptic feedback for telerobotic surgery systems in the two-channel force,position control scheme without the direct employment of force sensors at the end-effector of the slave robot. Copyright © 2010 John Wiley & Sons, Ltd. [source] Climatic signals in tree-rings of Araucaria angustifolia in the southern Brazilian highlandsAUSTRAL ECOLOGY, Issue 2 2010JULIANO MORALES OLIVEIRA Abstract Araucaria angustifolia (Bertol.) O. Kuntze (Araucariaceae) is a Neotropical tree, widely distributed in subtropical mountain rain forests and nearby natural grasslands of Southern Brazil. This species produces annual growth rings, but its dendroclimatic potential is barely known. In the present paper, the long-term growth patterns of A. angustifolia were investigated using annual growth ring time series and association to climate over the last century. Wood cores of A. angustifolia trees growing in forest and grassland habitats were obtained with an increment borer. The cores were surfaced, measured and cross-dated. The dated ring-width time series were standardized and submitted to correlation and principal component analysis to verify growth trends among sites and trees. Growth-climate relationships were investigated using correlation and regression analyses, comparing the ordination axes scores to regional time series of precipitation and temperature. Due to anatomical irregularities, mainly partial rings, only 35 out of 60 trees were cross-dated. The correlation and ordination analyses showed common tree-growth trends within and between sites, indicative of a regional environmental force determining inter-annual cambial activity variation. Despite growing in distinct habitats and disturbance regimes, A. angustifolia trees share a common long-term growth pattern, which is significantly related to thermal conditions during the current and previous growing seasons. Moreover, site-specific characteristics may have influenced opposite growth responses and association to climate conditions between forest and grassland trees. [source] Pan-glacial,a third state in the climate systemGEOLOGY TODAY, Issue 3 2009Paul F. Hoffman Radiative energy-balance models reveal that Earth could exist in any one of three discrete climate states,,non-glacial' (no continental ice-sheets), ,glacial-interglacial' (high-latitude ice-sheets) or ,pan-glacial' (ice-sheets at all latitudes),yet only the first two were represented in Phanerozoic time. There is mounting evidence that pan-glacial states existed at least twice in the Cryogenian (roughly 750,635 Ma), the penultimate period of the Neoproterozoic. Consensus is lacking on whether the world ocean was fully glaciated (,snowball' model) or largely unglaciated (,slushball' model). The first appearances of multicellular animal fossils (diapause eggs and embryos in China, and sponge-specific biomarkers in Oman), being closely associated with the last pan-glacial state, revive speculation that environmental forces had a hand in the origin of metazoa. [source] The poverty of economic explanations of consumption and an action theory alternativeMANAGERIAL AND DECISION ECONOMICS, Issue 3-4 2000Richard P BagozziArticle first published online: 27 MAR 200 The purpose of this essay is to critique economic conceptualizations of consumer behaviour and explanations of consumer choice, and to propose an alternative rooted in the philosophy of mind and action, as well as in nascent social psychological and marketing models of purposive behaviour. It is claimed that economic theory harbours ideological and methodological biases in how consumer behaviour is conceived and obscures understanding of the many decision processes constituting consumer behaviour and its causes and effects. A novel multistage model is proposed to account for consumer goal achievement/goal failure, where goal outcomes are hypothesized to be joint functions of consumer actions and physical, social, or other environmental forces. Consumer action, in turn, is proposed to begin with reasoning processes (subject to nonconscious biases found in neural operations), to undergo appraisals of anticipated goal outcomes, which are experienced as positive and negative emotions, to involve a subsequent integrative stage of desire production, where reasoning, emotional, and social processes are integrated and transformed into a decision to act or not, and finally to encompass additional affective and reasoning processes that are initiated in a stage termed, ,trying to consume', wherein decisions are planned and implemented, and goal-directed behaviours activated. Copyright © 2000 John Wiley & Sons, Ltd. [source] Reducing Obesity: Motivating Action While Not Blaming the VictimTHE MILBANK QUARTERLY, Issue 1 2009NANCY E. ADLER Context: The rise in obesity in the United States may slow or even reverse the long-term trend of increasing life expectancy. Like many risk factors for disease, obesity results from behavior and shows a social gradient. Especially among women, obesity is more common among lower-income individuals, those with less education, and some ethnic/racial minorities. Methods: This article examines the underlying assumptions and implications for policy and the interventions of the two predominant models used to explain the causes of obesity and also suggests a synthesis that avoids "blaming the victim" while acknowledging the role of individuals' health behaviors in weight maintenance. Findings: (1) The medical model focuses primarily on treatment, addressing individuals' personal behaviors as the cause of their obesity. An underlying assumption is that as independent agents, individuals make informed choices. Interventions are providing information and motivating individuals to modify their behaviors. (2) The public health model concentrates more on prevention and sees the roots of obesity in an obesogenic environment awash in influences that lead individuals to engage in health-damaging behaviors. Interventions are modifying environmental forces through social policies. (3) There is a tension between empowering individuals to manage their weight through diet and exercise and blaming them for failure to do so. Patterns of obesity by race/ethnicity and socioeconomic status highlight this tension. (4) Environments differ in their health-promoting resources; for example, poorer communities have fewer supermarkets, more fast-food outlets, and fewer accessible and safe recreational opportunities. Conclusions: A social justice perspective facilitates a synthesis of both models. This article proposes the concept of "behavioral justice" to convey the principle that individuals are responsible for engaging in health-promoting behaviors but should be held accountable only when they have adequate resources to do so. This perspective maintains both individuals' control and accountability for behaviors and society's responsibility to provide health-promoting environments. [source] Linking family dysfunction to suicidal ideation: Mediating roles of self-views and world-viewsASIAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 2 2009Sylvia Xiaohua Chen Research on suicide has documented various factors predicting suicidal ideation. The present study focused on the pathways emanating from one of the external, environmental forces (i.e. family dysfunction) through internal responses (beliefs about oneself and about the world), to suicidal ideation among Hong Kong Chinese. Using structural equation modelling, we tested the mediating roles of depressive self-views (including stress perception, depressive cognition and negative self-esteem) as well as two dimensions of social axioms (social cynicism and negative reward for application). Multi-group analysis showed that the mediation model was invariant across both males and females. Being socialized into a problematic family of origin affected multiple aspects of one's assessments of both oneself and one's world which, in turn, lead to greater suicidal ideation. Our findings provide important implications for assessing suicidal risk and guiding interventions in clinical treatment. [source] | |||||||||||||