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CLASSIFICATION AND ECOLOGICAL CHARACTERIZATION OF CONIFEROUS FOREST PHYTOGEOCOENOSES OF HOKKAIDO, JAPAN

VEGETATIO 1991年第1期96卷 25-42页

作者： KOJIMA, S 1. Program of Environmental Science Faculty of Liberal Arts Toyama University 3190 Gofuku 930 Toyama Japan

Coniferous forest phytogeocoenoses of Hokkaido Island, Japan, were studied to classify them based on vegetation characteristics, to analyse their soils, to correlate the vegetation and soil characteristics, and to provide some ecological interpretation for the phytogeocoenosis differentiation and establishment. Five forest types were distinguished based on the vegetation structure, each of which was comparable to plant association of Krajina (1.60);1. the moss type, 2. the Sasa kurilensis type, 3. the Sasa senanensis type, 4. the Carex sachalinensis type, and 5. the Dryopteris crassirhizoma type. Soil base status indicated by pH, electric conductivity, amount of calcium and magnesium, and base saturation showed a fair correlation with the forest types. The forest types were, therefore, arranged along a soil nutritional gradient. The moss type developed in the least fertile habitats whereas the Dryopteris crassirhizoma type in the most fertile habitats, and others were in between the two. It was suggested that in the island, where climate was humid with excess of soil water throughout a year, soil nutritional regime, more specifically availability of bivalent cations which tended to be removed by the excessive soil water, seemed to be a critical factor to differentiate and establish the forest types.

关键词： BIOGEOCLIMATOLOGY FOREST TYPE SOIL CHEMISTRY VEGETATION-SOIL RELATIONSHIPS

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RELEVANCE AS AN EXPLANATION OF COMMUNICATION

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LINGUISTICS AND PHILOSOPHY 1991年第4期14卷 453-472页

作者： ROBERTS, LD 1. Program in Philosophy and Computer and Systems Science Department of Philosophy State University of New York at Binghamton 13902-6000 Binghamton NY USA

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THE COMPLEXITY OF RANKING SIMPLE LANGUAGES

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MATHEMATICAL SYSTEMS THEORY 1990年第1期23卷 1-19页

作者： HUYNH, DT 1. Computer Science Program University of Texas at Dallas 75083 Richardson TX USA

Ranking is the problem of computing for an input string its lexicographic index in a given (fixed) language. This paper concerns the complexity of ranking. We show that ranking languages accepted by 1.way unambiguous auxiliary pushdown automata operating in polynomial time is inNC (2). We also prove negative results about ranking for several classes of simple languages.C is rankable in deterministic polynomial time iffP=P #P , whereC is any of the following six classes of languages: (1. languages accepted by logtime-bounded nondeterministic Turing machines, (2) languages accepted by (uniform) families of unbounded fan-in circuits of constant depth and polynomial size, (3) languages accepted by 2-way deterministic pushdown automata, (4) languages accepted by multihead deterministic finite automata, (5) languages accepted by 1.way nondeterministic logspace-bounded Turing machines, and (6) finitely ambiguous linear context-free languages.

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AN ADVECTIVE MIXED-LAYER MODEL FOR HEAT AND MOISTURE INCORPORATING AN ANALYTIC-EXPRESSION FOR MOISTURE ENTRAINMENT

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BOUNDARY-LAYER METEOROLOGY 1990年第1-2期53卷 21-31页

作者： STEYN, DG 1. Atmospheric Science Program Department of Geography The University of British Columbia B.C. Canada

A slab mixed-layer model with zero-order entrainment for both temperature and humidity is developed in order to examine the relative magnitude of advective and turbulence flux convergence effects. The model formulation provides an analytic function for the ratio of surface-layer to entrainment-layer humidity flux. Model results are compared with measured mixed-layer properties over one day at a coastal location. It is concluded that the model is highly successful at simulating the mixed-layer depth, and mean mixed-layer humidity. It is suggested that a first-order model may be more appropriate for the latter half of the day when the mixed-layer depth is decreasing due to the dominance of advection over vertical turbulence flux convergence.

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THE MEANING AND ETHICS OF SUSTAINABILITY

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ENVIRONMENTAL MANAGEMENT 1990年第1期14卷 1-8页

作者： SHEARMAN, R 1. Graduate Program in Environmental Science State University of New York College of Environmental Science and Forestry 13210 Syracuse New York USA

Some have argued that the meaning of sustainability varies according to context, forcing us to be as explicit as possible when defining our terms. An argument is offered that disputes this conclusion by maintaining that it is not the meaning of sustainability that changes with respect to context, but rather our understanding of the context itself. This is frequently apparent in contradictions that arise when conceiving each context in terms of sustainability. If this argument is correct, then we should be concerned not with the “meaning” of sustainability but rather the implications of sustainability as they affect the status quo. And in order to do this we must be prepared to answer the question: Why is sustainability desirable? This approach is illustrated through a preliminary conceptual and ethical analysis of ecologically sustainable development.

关键词： Sustainability Ecologically sustainable development Ethics

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BINATIONAL MANAGEMENT OF HAZARDOUS-WASTE - THE MAQUILADORA INDUSTRY AT THE UNITED-STATES MEXICO BORDER

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ENVIRONMENTAL MANAGEMENT 1990年第4期14卷 441-450页

作者： PERRY, DM SANCHEZ, R GLAZE, WH MAZARI, M 1. Environmental Science and Engineering Program School of Public Health University of California 90024-1772 Los Angeles California USA

Foreign-owned industry in the form of assembly plants, termed maquiladora, has become very important in Mexico to the extent that it represents the second largest source of foreign exchange and is a valuable source for employment and regional development. The economic prosperity gained from the rapid growth of the maquiladora industry has been accomapanied by increased environmental and human health risks associated with generation of hazardous waste. Diversification of industry has resulted in the predomination of those sectors that likely use hazardous substances. The Mexicali-Calexico border region was selected to demonstrate the potential for environmental and health risks associated with the generation of hazardous waste. Estimates for the generation of hazardous waste were obtained from 34 maquiladora plants in Mexicali, represented by the electronic and electronic equipment and parts, mechanical and transportation equipment, and toys and sporting equipment sectors. Repeated detection of volatile organic compounds in the New River at the US-Mexico border suggests that hazardous waste from the printed circuit board industry in Mexicali is not being disposed of in a proper manner. Potential adverse health effects, such as carcinogenic and mutagenic responses associated with the detected volatiles, are discussed. US and Mexico national legislation and the Binational Environmental Agreement were examined for their adequacy to ensure proper management of hazardous waste generated by the maquiladora industry. Environmental policy options are presented that focus on: (1. increased environmental accountability of US parent companies for their maquiladora assembly plants in Mexico;and (2) more integration between US Customs and border states with the US Environmental Protection Agency to improve the binational management of hazardous waste generated by the maquiladora industry.

关键词： Hazardous waste Maquiladora industry Environmental policy US-Mexico border

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FEASIBILITY ISSUES IN A PRIMAL DUAL INTERIOR-POINT METHOD FOR LINEAR-programMING

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MATHEMATICAL programMING 1990年第2期49卷 145-162页

作者： LUSTIG, IJ 1. Program in Statistics and Operations Research Department of Civil Engineering and Operations Research School of Engineering and Applied Science Princeton University 08544 Princeton NJ USA

A new method for obtaining an initial feasible interior-point solution to a linear program is presented. This method avoids the use of a "big-M", and is shown to work well on a standard set of test problems. Conditions are developed for obtaining a near-optimal solution that is feasible for an associated problem, and details of the computational testing are presented. Other issues related to obtaining and maintaining accurate feasible solutions to linear programs with an interior-point method are discussed. These issues are important to consider when solving problems that have no primal or dual interior-point feasible solutions.

关键词： LINEAR programMING INTERIOR-POINT METHODS PRIMAL-DUAL ALGORITHMS FEASIBILITY

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ZOOPLANKTON CAPTURE BY A CORAL-REEF FISH - AN ADAPTIVE RESPONSE TO EVASIVE PREY

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ENVIRONMENTAL BIOLOGY OF FISHES 1990年第1期29卷 35-42页

作者： COUGHLIN, DJ STRICKLER, JR 1. Biological Science Center Boston University Marine Program 5 Cummington St. Boston MA 02215 U.S.A.

High-speed cinematography and video using modified Schlieren optics and laser illumination helped elicit details of prey capture mechanisms used by Chromis viridis while feeding on calanoid copepods and Artemia. Chromis viridis is capable of a ram-jaw, low-suction feeding, as well as a typical suction feeding behavior described for other species of planktivores. By adjusting the degree of jaw protrusion and amount of suction used during a feeding strike, this fish can modulate its feeding strikes according to the prey type being encountered. The ram-jaw feeding mode enables C. viridis to capture highly evasive calanoid copepods within 6 to 1. msec. The use of specialized feeding behavior for evasive prey and the ability to vary feeding behavior are adaptations for feeding on evasive prey.

关键词： Pomacentridae Chromis viridis Zooplanktivore Water column forager Suction feeding Ram-jaw feeding

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A NEW ALGORITHM FOR SCHEDULING PERIODIC, REAL-TIME TASKS

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ALGORITHMICA 1989年第2期4卷 209-219页

作者： LEUNG, JYT 1. Computer Science Program University of Texas at Dallas 75080 Richardson TX USA

We consider the problem of preemptively scheduling a set of periodic, real-time tasks on a multiprocessor computer system. We give a new scheduling algorithm, the so-called Slack-Time Algorithm, and show that it is more effective than the known Deadline Algorithm. We also give an (exponential-time) algorithm to decide if a task system is schedulable by the Slack-Time or the Deadline Algorithm. The same algorithm can also be used to decide if a task system is schedulable by any given fixed-priority scheduling algorithm. This resolves an open question posed by Leung and Whitehead. Finally, it is shown that the problem of deciding if a task system is schedulable by the Slack-Time, the Deadline, or any given fixed-priority scheduling algorithm is co-NP-hard for each fixedm≥.

关键词： Periodic Real-time tasks Multiprocessor system Schedulability co-NP-hard

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EXPLICIT INCORPORATION OF THE ENERGY-BAND STRUCTURE INTO AN ANALYSIS OF THE DEFECT CHEMISTRY OF PBTE AND SNTE

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JOURNAL OF ELECTRONIC MATERIALS 1989年第3期18卷 421-443页

作者： SHA, YG BREBRICK, RF 1. Program of Materials Science and Metallurgy College of Engineering Marquette University 53233 Milwaukee WI

A framework is established for the analysis of the defect chemistry of the entire (Pb1.x Sn x )1.y Te y system based upon statistical thermodynamic calculations and experimentally measured carrier-concentration and t... 详细信息

A framework is established for the analysis of the defect chemistry of the entire (Pb_1.xSn_x)_1.yTe_y system based upon statistical thermodynamic calculations and experimentally measured carrier-concentration and tellurium partial-pressure data. The energy-band structure, in which inversion of light-mass, non-parabolic, direct-gap bands occurs and a second, parabolic valence band is present, is explicity incorporated into the analysis for the first time and the usual non-degeneracy assumption is abandoned. The densities of states of the non-ellipsoidal bands and the Fermi levels are calculated numerically. The remaining intrinsic material parameters (the partial pressure of tellurium over intrinsic, pure material and the Schottky constant for doubly-ionized vacancies) are then determined by the fit to the carrier concentration-partial pressure-temperature data. The model established is applied to only PbTe and SnTe because of the lack of partial-pressure data for the ternary solid solutions and satisfactory fits are obtained. The Fermi level lies in the light-mass valence band of SnTe for all of the observed carrier concentrations so that previous analyses of SnTe, which assumed that the hole distribution is non-degenerate, were in error. The 1.at. % wide homogeneity range of SnTe is wide enough that a compositional variation in the sum of the chemical potentials of tin and tellurium has been detected experimentally. This variation is theoretically zero in the usual models for narrow homogeneity-range compounds, but is accounted for in this analysis. Quantitatively satisfactory fits are obtained for PbTe using 0.85mo for the density-of-states effective mass which characterizes the second, parabolic valence band extrema. Only slightly poorer fits are obtained with the roughly established value of 1.0m _o. To obta

关键词： PbTe SnTe defect chemistry band structure enthalpy of defect creation

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