1,623 research outputs found

    ATTITUDES AND HOUSEHOLD CHARACTERISTICS INFLUENCING SOLID WASTE GENERATION: A HOUSEHOLD GARBAGE ANALYSIS

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    A survey of household decision-makers and an analysis of their garbage was used to suggest factors affecting the weight of household contributions to municipal solid waste. Iterative regression was used to build a model from the data that is hypothesized to explain garbage weight. Food expenditure, environmental attitude, consumption of soft drinks in plastic bottles, and cats in the household were significant for all households. Self-sufficiency and energy-conscious behavioral scales also affected the subgroup with female householders having an educational level of high school graduation or less.Environmental Economics and Policy,

    Quasilocal Conservation Laws: Why We Need Them

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    We argue that conservation laws based on the local matter-only stress-energy-momentum tensor (characterized by energy and momentum per unit volume) cannot adequately explain a wide variety of even very simple physical phenomena because they fail to properly account for gravitational effects. We construct a general quasi}local conservation law based on the Brown and York total (matter plus gravity) stress-energy-momentum tensor (characterized by energy and momentum per unit area), and argue that it does properly account for gravitational effects. As a simple example of the explanatory power of this quasilocal approach, consider that, when we accelerate toward a freely-floating massive object, the kinetic energy of that object increases (relative to our frame). But how, exactly, does the object acquire this increasing kinetic energy? Using the energy form of our quasilocal conservation law, we can see precisely the actual mechanism by which the kinetic energy increases: It is due to a bona fide gravitational energy flux that is exactly analogous to the electromagnetic Poynting flux, and involves the general relativistic effect of frame dragging caused by the object's motion relative to us.Comment: 20 pages, 1 figur

    Effects of Lodgepole Pine Dwarf Mistletoe, Arceuthobium americanum, on Jack Pine, Pinus banksiana, Growth in Manitoba

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    The Lodgepole Pine Dwarf Mistletoe (Arceuthobium americanum Nutt. ex Engelm.) is an important pathogen of Jack Pine (Pinus banksiana Lamb.). Dwarf Mistletoe alters tree form, suppresses growth, and reduces volume and overall wood quality of its host. Stem analysis and a 3-parameter logistic regression model were used to compare the growth of heavily and lightly to non infected Jack Pine trees. At the time of sampling, no significant reduction in diameter at breast height and basal area were observed in heavily infected trees. However, a significant reduction in height and volume and an increase in taper were observed in heavily infected trees. Growth models predicted a 21.1% lower basal area, 23.4% lower height and 42.1% lower volume by age 60 for the high infection group

    Properties of the symplectic structure of General Relativity for spatially bounded spacetime regions

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    We continue a previous analysis of the covariant Hamiltonian symplectic structure of General Relativity for spatially bounded regions of spacetime. To allow for near complete generality, the Hamiltonian is formulated using any fixed hypersurface, with a boundary given by a closed spacelike 2-surface. A main result is that we obtain Hamiltonians associated to Dirichlet and Neumann boundary conditions on the gravitational field coupled to matter sources, in particular a Klein-Gordon field, an electromagnetic field, and a set of Yang-Mills-Higgs fields. The Hamiltonians are given by a covariant form of the Arnowitt-Deser-Misner Hamiltonian modified by a surface integral term that depends on the particular boundary conditions. The general form of this surface integral involves an underlying ``energy-momentum'' vector in the spacetime tangent space at the spatial boundary 2-surface. We give examples of the resulting Dirichlet and Neumann vectors for topologically spherical 2-surfaces in Minkowski spacetime, spherically symmetric spacetimes, and stationary axisymmetric spacetimes. Moreover, we show the relation between these vectors and the ADM energy-momentum vector for a 2-surface taken in a limit to be spatial infinity in asymptotically flat spacetimes. We also discuss the geometrical properties of the Dirichlet and Neumann vectors and obtain several striking results relating these vectors to the mean curvature and normal curvature connection of the 2-surface. Most significantly, the part of the Dirichlet vector normal to the 2-surface depends only the spacetime metric at this surface and thereby defines a geometrical normal vector field on the 2-surface. Properties and examples of this normal vector are discussed.Comment: 46 pages; minor errata corrected in Eqs. (3.15), (3.24), (4.37) and in discussion of examples in sections IV B,

    An Investigation of Online and Face-to-Face Communication in General Chemistry

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    This exploratory study investigated an online office hour and a face-to-face recitation for similarities and differences. The online office hour and face-to-face recitation were a part of general chemistry courses taught at different universities. The courses covered the same material at the same level. The results of the investigation revealed that in the online environment students must articulate their ideas clearly to convey them in a text-only medium. The written text seemed to help the instructor to identify misinterpretations made by the students. The instructor-dominated hierarchy between instructor and student is present in both environments. When comparing the percentage of total student and instructor events (the sum of questions and statements) in the online environment, students’ events were significantly greater than instructor’s events. This finding is an indication that the online environment shows promise for improving student participation
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