bluuebunny/crossref_metadata_2025 huggingface dataset:
The petrogenesis and implications of deformed late Caledonian–early Hercynian granites in the Wuyi area, South China
Authors: Zhao Xilin , Jiang Yang , Xing Guangfu , Yu Minggang , Liu Kai , Chen Zhihong , Yu Shengyao
Published: June 2017

Precambrian basement rocks have been affected by Caledonian thermal metamorphism. Caledonian‐aged zircon grains from Precambrian basement rocks may have resulted from thermal metamorphism. However, Hercynian ages are rarely recorded. Zircon U–Pb Sensitive High Resolution Ion Microprobe (SHRIMP) dating reveals that zircon ages from the Huyan, Lingdou, and Pengkou granitic plutons can be divided into two groups: one group with ages of 398.9 ±5.3 Ma, 399 ±5 Ma, and 410.2 ±5.4 Ma; and a second group with ages of 354 ±11 Ma, 364.6 ±6.7 Ma, and 368 ±14 Ma. The group of zircon U–Pb ages dated at 410–400 Ma represent Caledonian magmatism, whereas the 368–354 Ma ages represent the age of deformation, which produced gneissosity. The three plutons share geochemical characteristics with S‐type granites and belong to the high‐K calc‐alkaline series of peraluminous rocks. They have (87Sr/86Sr)i ratios of 0.710 45–0.724 68 and εNd(t) values of −7.33 to −10.74, with two‐stage Nd model ages (TDM2) ranging from 1.84 Ga to 2.10 Ga. Magmatic zircon εHf(t) values range from −3.79 to −8.44, and have TDMC ages of 1.65–1.93 Ga. The data suggest that these granites formed by partial melting of Paleoproterozoic to Mesoproterozoic continental crust. A collision occurred between the Wuyi and Minyue microcontinents within the Cathaysia Block and formed S‐type granite in the southwest Fujian province. The ca 360 Ma zircon U–Pb ages can represent a newly recognized period of deformation which coincided with the formation of the unified Cathaysia Block.
Association between physical and depressive symptoms during the first 6 months postpartum
Authors: Mori Emi , Iwata Hiroko , Sakajo Akiko , Maehara Kunie , Tamakoshi Koji
Published: June 2017

Aim

To examine the relationship between physical symptoms and depressive symptoms among new mothers during the first 6 months postpartum.

Methods

Prospective cohort study design was used in this study. Participants were recruited in 13 Japanese hospitals between 2012 and 2013. A total of 2709 women (response rate of those invited 71.9%) provided longitudinal data using self‐report questionnaires at 5 time points: during the hospital stay and at 1, 2, 4, and 6 months postpartum. Depressive symptoms were measured using the Japanese version of the Edinburgh Postnatal Depression Scale. Also, 37 physical symptoms were measured using a yes‐or‐no checklist. To examine the association between physical symptoms and depressive symptoms, logistic regression analysis was used.

Results

There was a significant positive association between physical symptoms and depressive symptoms during the first 6 months postpartum. Fifteen physical symptoms were associated with significantly increased odds of depression at 1, 2, 4, and 6 months post‐partum. These symptoms included: loss of appetite, tiredness/languor, and palpitation/shortness of breath.

Conclusion

Multiple physical symptoms after childbirth were associated with depressive symptomatology. Health professionals should assess for postpartum depression when puerperal women report multiple physical symptoms as independent complaints.
Postpartum maternal function and parenting stress: Comparison by feeding methods
Authors: Maehara Kunie , Mori Emi , Iwata Hiroko , Sakajo Akiko , Aoki Kyoko , Morita Akiko
Published: June 2017

Aim

This cross‐sectional and longitudinal study explored primiparous mothers' functioning and parenting stress on the basis of infant‐feeding method over the first 6 months postpartum.

Methods

Participants were Japanese primiparae who delivered live singleton infants (N = 1120). Questionnaires, completed at 1, 2, 4, and 6 months postpartum, included demographics, feeding method, frequency of feedings, time required from infant's feeding to falling asleep, mother's sleep time, Postnatal Accumulated Fatigue Scale, and the original Japanese version of Parenting Stress Short‐Form Scale. Chi‐square tests and Welch F tests for one‐way analysis of variance were conducted.

Results

Exclusively breastfeeding mothers fed their infants more frequently, but required less time from infant's feeding to falling asleep than either mixed or formula‐feeding mothers. Mixed feeding mothers required more time for infant feeding and reported more severe fatigue and greater parenting stress than breastfeeding mothers at 1 and 2 months postpartum. Exclusively formula‐feeding mothers required more time to get their infant back to sleep and reported greater parenting stress than the other groups at 6 months postpartum. Nearly 25% of mothers continued breastfeeding exclusively through the first 6 months postpartum. Mothers often changed feeding methods, with many exclusively breastfeeding by 6 months.

Conclusion

Feeding methods may affect maternal functioning and parenting stress across the postpartum period.
Consensus development of quality indicators for end‐of‐life care for elders in Japan
Authors: Masaki Harue , Kawai Nobuko , Matsumoto Keiko , Kuwata Miyoko , Yoshioka Sachiko , Nishiyama Midori , Uchino Ryoko , Nagae Hiroko , Teshima Megumi , Sakai Sayuri , Endo Kazuko
Published: June 2017

Aims and objectives

Quality indicators for end‐of‐life care have been published; however, none have been developed specifically for nursing in the cultural and traditional context of Japan. This study aimed to develop and build a consensus of quality indicators for end‐of‐life care for elders in Japan from the perspective of nursing science.

Methods

To develop the quality indicators, we used a literature review, expert panel process, and the Delphi technique among clinical nurse specialists in geriatrics.

Results

Quality indicators were identified in 7 major areas: advance directives and surrogate continuity, ethical daily care, care preferences and decisions about life‐sustaining treatment, assessment and management of pain and other symptoms, daily care for the dying, family care, and institutional systems for end‐of‐life care.

Conclusions

These quality indicators represent the first attempt to develop a best practices approach toward improving the quality of elderly end‐of‐life care in nursing.
SEARCH THEORY IN NATURAL RESOURCE MODELING
Authors: Mangel Marc , Clark Colin
Published: June 2017

The role of search theory in the exploitation of natural resources is discussed in this paper. After a brief history and taxonomy of search problems, the mathematics of search is discussed. This includes underlying probability distributions, the differential equations of search, Bayesian use of search information and optimization problems in search theory. The theory is illustrated by applications in fisheries, pest control, animal foraging, and oil and mineral exploration.
ECONOMIC REGULATION OF TARGETING BEHAVIOR IN MULTISPECIES FISHERY
Authors: McKelvey Robert
Published: June 2017

Fishing vessels, harvesting geographically dispersed and heterogeneous multispecies aggregates, are presumed to target on the most profitable pools. But, this behavior may lead to depletion of biologically valuable species, and consequent early closure by the management agency of the entire fishery.

In this article, a simple model is analyzed in order to understand the dynamics of such targeting behavior. Further analysis explores the theoretical extent to which targeting might be altered through economic rationalization measures, landings taxes or quota markets, to achieve a more nearly optimal pattern of exploitation.
OPTIMIZING ECOSYSTEM SIMULATION MODEL PERFORMANCE
Authors: Loehle Craig
Published: June 2017

The utility of ecosystem simulation models may be limited by computer resources under certain circumstances. This paper describes straightforward techniques for decreasing CPU usage by removing invariants from loops, minimizing type conversions, subscripting correctly, zeroing arrays efficiently, optimizing code locality, and minimizing subroutine calls. Expensive I/O activity may be reduced by creating “separate” optional output files for intermediate variables, and by judicious choice of printing interval. Memory usage may be reduced by re–using arrays. All these techniques are readily accessible to scientists not intensively trained in computer science.
ADAPTIVE MANAGEMENT OF HARVEST RATES IN THE PRESENCE OF A RISK AVERSE UTILITY FUNCTION
Authors: Walters Carl , Ludwig Don
Published: June 2017

Previous research on adaptive harvest strategies has suggested that it should rarely be optimal to introduce deliberate, probing variations in harvest rates in order to reduce uncertainty about production parameters, when there is strong aversion to the risk of low catches. Here we show that this suggestion is incorrect for cases where the stock dynamics can be approximated by a simple power model and the objective is to maximize the sum over time of discounted logarithms of catches. In such cases, the objective function has a simple form that permits easy comparison between passively adaptive (certainty equivalent or cautious) versus actively adaptive policies involving probing variation in harvest rates. Probing is favored when there is high uncertainty about the power parameter that represents density dependence in the stock dynamics.
AN OPTIMAL CONTROL MODEL FOR ANALYSIS OF TIMBER RESOURCE UTILIZATION IN SOUTHEAST ASIA
Authors: Lyon Kenneth S. , Sedjo Roger A. , Adiwiyoto Bambang P.
Published: June 2017

A discrete time optimal forestry model is built and a shooting method solution algorithm identified. The applicability of the model and algorithm to public policies that affect forestry resources is demonstrated in an application of the model to examine the development of wood processing capacity in Southeast Asia. The necessary conditions of the optimal control model are manipulated to identify a difference equation problem with initial and terminal conditions. The solution to this boundary value problem is identified using a search routine that repetitively, numerically evaluates (shoots) the difference equations. The solution is the trajectory that satisfies the initial and terminal conditions.
ON THE OPTIMAL POLICY FOR COMBINED HARVESTING OF INDEPENDENT SPECIES
Authors: Mesterton‐Gibbons Michael
Published: June 2017

By a combination of analytical reasoning and numerical experiment it is demonstrated that, for the combined harvesting of two ecologically independent species which grow logistically and are harvested at a rate proportional to both stock level and effort, there is a unique attainable equilibrium which yields positive revenue and to which the approach path satisfies all of Pontryagin's necessary conditions for maximizing the harvest's present value. A simple feedback law governs this approach and is conjectured to be the optimal policy. On that basis, criteria are found for the survival of the less productive species, as a function of the system parameters and initial stocks. An economic interpretation of the equilibrium is also given.
BOOK REVIEW
Authors: Hastings Alan
Published: June 2017

STABILITY OF BIOLOGICAL COMMUNITIES, Yu M. Svirezhev D.O. Logofet, MIR Publishers, Moscow, 1983, 319 pp.
DATA UNCERTAINTY, MODEL AMBIGUITY, AND MODEL IDENTIFICATION
Authors: Schnute Jon
Published: June 2017

This paper is based on a talk presented at the 1986 Resource Modeling Conference in Newport, Oregon. It addresses the problem of resource model identification, that is, the question: Which of various competing models correctly describes the resource? A major theme of the paper is the proposition that data uncertainty and model ambiguity are fundamentally intertwined. In some cases this relationship can be proved rigorously; consequently, model ambiguity can be inevitable. In other cases, promising identification techniques are suggested by modern statistical theory, and the paper examines some of these in the context of time series analysis. Throughout the paper, theoretical and practical examples illustrate both limitations and possibilities for using resource models as valid descriptors of reality.
BOOK REVIEW
Authors: Silvert William
Published: June 2017

ECOLOGICAL SIMULATION PRIMER, Gordon L. Swartzman Stephen P. Kalunzy, Macmillan Publishing Company, New York, 1987.
IRREVERSIBLE INVESTMENT AND OPTIMAL FOREST EXPLOITATION
Authors: Allard Jacques , Errico Darrel , Reed William J.
Published: June 2017

A forest harvest scheduling model which includes as activities the level of investment in harvest capacity and the accumulated harvest capacity in each period, is presented. The inclusion of these activities, in addition to the harvest activities, allows for the removal of harvest‐flow constraints found in more typical Model II formulations of the harvest scheduling problem. The optimal harvest and investment policy can be determined by linear programming or quadratic programming methods, depending on whether prices are constant or supply‐dependent. The new model better reflects economic reality than existing models, and provides a method for determining the optimal economic development of a forest industry, and the optimal draw‐down of old growth forest. Numerical examples are given.
IN‐SEASON FISHERY MANAGEMENT: A BAYESIAN MODEL
Authors: Charles Anthony T.
Published: June 2017

A Bayesian model is presented for optimizing harvest rates on an uncertain resource stock during the course of a fishing season. Pre‐season stock status information, in the form of a “prior” probability distribution, is updated using new data obtained through the operation of the fishery, and harvest rates are chosen to achieve a balance between conservation concerns and fishing interests. A series of fishery scenarios are considered, determined by the stock size distribution and the timing distribution; the uncertainty in the fish stock is seen to have a rather complex influence on optimal harvest rates. The model is applied to a specific example, the Skeena River sockeye salmon fishery.
BOOK REVIEW
Authors: Baskerville G.L.
Published: June 2017

ADAPTIVE MANAGEMENT OF RENEWABLE RESOURCES, Carl Walters, MacMillan Publishing Co New York, Collier MacMillan Publishers London, 1986, 374pp ISBN 0‐02‐947970‐3
ON THE OPTIMAL POLICY FOR COMBINING HARVESTING OF PREDATOR AND PREY
Authors: Mesterton‐Gibbons Michael
Published: June 2017

An optimal policy is sought for maximizing present value from the combined harvest of two ecologically dependent species, which would coexist as predator and prey in the absence of harvesting. Harvest rate for each species is assumed proportional to both stock level and effort. For a large class of biological productivity functions, it is established that the optimal equilibrium point in the phase‐plane of stock levels must be a saddle‐point. For quadratic productivity functions, a combination of analytical reasoning and numerical experiment is used to show that first and second order necessary conditions for optimality are satisfied by a unique approach to equilibrium, which must therefore be optimal. The corresponding control law is given, and an apparent suggestion of two previous authors concerning the policy is shown to be inappropriate. The optimal policy enables an estimate to be made of the true loss of resource value due to a catastrophic fall in stock level.
OPTIMAL HARVESTING WITH DENSITY DEPENDENT RANDOM EFFECTS
Authors: Hanson Floyd , Ryan Dennis
Published: June 2017

We consider the effect of sudden large, randomly occurring density dependent disasters on the optimal harvest policy and optimal expected return for an exploited population. The population is assumed to grow logistically with disasters occurring on a time scale very short compared to the natural growth scale. The case of a density dependent disaster frequency is also treated. Stochastic dynamic programming is used in the optimization. For a set of realistic field data it is found that random effects typically have a significant effect on both optimal return and optimal effort levels. The effect of density dependence is far more pronounced for optimal return than for optimal effort levels.
MODELS FOR COOPERATION AND CONSPIRACY IN FISHERIES: CHANGING THE RULES OF THE GAME
Authors: White G.N. , Mace P.
Published: June 2017

Fisheries regulation is considered necessary to counteract the effects of competitive forces which can lead to a “tragedy of the commons”. Yet management initiatives have often failed because they did not take into account competitive responses of fishing enterprises. In particular, open access fisheries provide strong incentives for the development of excessive harvesting capacity. This in turn leads to harvesting that is concentrated in space and time, with adverse effects on both the resource and markets. A coalition of fishermen, such as a fishermen's cooperative, has interests similar to those of a sole owner, and thus would be expected to produce more efficient behaviour. In practice, however, fishermen's cooperatives seldom persist. Game theory is used to explore relationships between the coalition structure of the industry, economic variables, and regulation. The models are based loosely on a purse seine fishery for herring. The results suggest that the potential to form stable coalitions is affected by changes in price and harvest. Changes in regulation also affect stability of coalitions. When interpreted in the light of historical changes in the herring fishery, these results suggest that industry may not accept regulations which do not permit formation of stable coalitions.
A SEQUENTIAL APPROACH TO DERIVATION OF STAND TREATMENT AND FOREST‐WIDE HARVEST PRESCRIPTION OR SUPPLY
Authors: Barber Richard L. , Brodie J. Douglas
Published: June 2017

Current methods for optimization of stand treatment and forest‐wide harvest scheduling use mathematical programming that presumes perfect information on production, costs, and revenues over long planning periods. These approaches simultaneously optimize harvest for all periods in the planning horizon. In contrast, the method presented here assumes that stand‐level planning and harvest scheduling proceed sequentially rather than simultaneously over every period. A backward‐recursion dynamic program is used to determine the discounted net value of a wide range of current harvest strategies for each stand class in the forest inventory on the basis of a projected set of optimal treatments for future harvest and regeneration of each stand. The most highly valued strategy is selected if there are no volume constraints. Otherwise, suboptimal harvest alternatives are ranked in order of increasing opportunity cost for increasing or decreasing harvest; constraints met only up to a maximum opportunity cost is also demonstrated.
NATURAL RESOURCE ECONOMICS UNDER UNCERTAINTY: EFFECT OF FUTURES MARKETS
Authors: Mueller Michael J.
Published: June 2017

The effects of hedging and time‐dependent price and geological uncertainty on the behavior of a firm exploiting a nonrenewable natural resource are derived. Contrasts in behavior with and without hedging and uncertainty are identified and discussed. Much of the analysis centers on the firm's implicit value of its in situ reserves, marginal user cost. The main result is that time‐dependent uncertainty lowers the implicit value of reserves. Hedging ameliorates this effect somewhat. Under some conditions even with risk reducing hedging, the firm tilts its extraction and development paths toward the present and may also shorten its decision‐making time horizon.
ON DEVELOPMENT, FISHERIES AND DYNAMITE: A BRIEF REVIEW OF TROPICAL FISHERIES MANAGEMENT
Authors: Pauly Daniel , Silvestre Geronimo , Smith Ian R.
Published: June 2017

Some features of underdevelopment in Third World countries are reviewed with emphasis on their impact on fisheries and fisheries management. Poverty in rural communities is highlighted as the key issue preventing rational management of tropical inshore fisheries and shown to be ‐ along with (misguided) export‐oriented development strategies ‐ the root cause for destructive fishing techniques and environmental degradation. Some implications for modelling are outlined.

A reorientation of investments towards job creation in fish‐erfolk and other rural communities is advocated as the key aspect of any solution of fisheries problems in Third World countries.
BOOK REVIEW
Authors: Mangel Marc
Published: June 2017

VIABLE POPULATIONS FOR CONSERVATION, Michael E. Soule, editor Cambridge University Press, Cambridge, UK, 1987
PERSISTENCE IN AN AGE‐STRUCTURED POPULATION FOR A PATCH‐TYPE ENVIRONMENT
Authors: Allen Linda J.S. , Moulton Michael P. , Rose Francis L.
Published: June 2017

A discrete‐time model for an age‐structured population in a patch‐type environment is presented and analyzed. Comparison techniques for difference equations are used to find sufficient conditions for population persistence or extinction. The persistence and extinction theorem is used to define the critical patch number, the threshold for population persistence. Several examples are presented which illustrate the results of the theorems. The model is applied to a watersnake population.
YEAR AROUND CLOSED AREAS AS A MANAGEMENT TOOL
Authors: Polacheck Tom
Published: June 2017

Year around closed areas or refuges as management mechanisms for controlling fishing mortality are explored using a two‐component, spatial model with movement between areas. The model assesses the fate of a cohort when only a portion of it is vulnerable to fishing. The yield per recruit and spawning stock biomass per recruit are compared for equivalent amounts of fishing effort with and without a refuge.

The results indicate that the institution of a closed area can lead to substantial increases in spawning stock biomass realized from a cohort and, as such, could be a viable short‐term management option to reduce overall fishing mortality on an overexploited stock. Yield per recruit with a refuge is a complex function of the size of the refuge, fishing mortality rates and movement rates. The results suggest that the proportional loss in yield per recruit will be less than the initial proportion of the cohort contained within the refuge. In some instances, the yield per recruit with a refuge can exceed the yield per recruit without one, but the net increases are usually small. The size of the refuge needed to achieve a specified gain in spawning biomass depends upon the mobility of the fish. Higher movement rates require a larger refuge to achieve the same increase, but any loss in yield per recruit will be less even though the refuge is larger.

The assumptions underlying the model are discussed, and the importance of information on movement rates for assessing the possible effect of closed areas is stressed.
OPTIONS FOR THE REGULATION OF MEDITERRANEAN DEMERSAL FISHERIES
Authors: Caddy J.F.
Published: June 2017

Research and management actions are reviewed with respect to demersal fisheries of the Mediterranean since the Second World War, as reflected in the activities of the General Fisheries Council for the Mediterranean, (GFCM). The scientific background to the priority concern expressed for minimum size limits in the 1960's and 1970's is discussed, and in particular, the mesh selectivity experiments that formed the basis for yield per recruit calculations, with respect to the trawl fishery. More recent considerations, changing our perception of the appropriateness of size at first capture of demersal fish as a management tool in trawl fisheries, are reviewed.

It is concluded that for multispecies fisheries where the first priority for fishing effort control is not respected, size limits based on size at maturity, rather than yield per recruit criteria, are more feasible, but that changes in mesh size need to take into account subsequent changes in equity between inshore and offshore fleets, and changes in species composition and areas of distribution during the life history. They also need to consider the high landed value of small fish in many Mediterranean fisheries. Alternative, or supplementary, measures to mesh size regulation that affect capture of small fish are also reviewed, including seasonal closures, closed areas, bans on trawling inshore, and regulations on minimum size at sale.

A range of problems to be considered prior to deciding on an increase in mesh size are reviewed, including changes in total effort exerted, changes in increases in fishing power (and especially the impacts on the spawning stock), changes in discard rate, “meshing” of small fish, and indirect mortality during fishing. A strategy for introducing new mesh sizes is suggested, with emphasis, where possible, on the experimental approach, and on supplementary measures to control fishing effort.

The paper concludes by considering an alternative paradigm to minimum size regulation for demersal fisheries management; namely, the exploitation of juvenile fish, with provision for escapement of a small proportion of large, mature fish offshore, for which exploitation rate declines and remains low. It is suggested that this strategy may be, de facto, the one prevailing in the small mesh size inshore trawl fishery prior to development of offshore fisheries. The implications of this possibility have to be considered seriously if high effort levels are to be maintained while effective size limits are raised.
BOOK REVIEW
Authors: Conrad Jon M.
Published: June 2017

MATHEMATICAL BIOECONOMICS: THE OPTIMAL MANAGEMENT OF RENEWABLE RESOURCES, Colin W. Clark, Second Edition, John Wiley & Sons, Inc., New York, 1990
BOOK REVIEW
Authors: Biles Charles M.
Published: June 2017

QUANTITATIVE ECOLOGICAL THEORY, Michael R. Rose, The Johns Hopkins University Press, Baltimore, MD 1987
OPTIMAL AUSTRALIAN AND JAPANESE HARVESTING OF SOUTHERN BLUEFIN TUNA
Authors: Kennedy John O.S. , Pasternak Hanoch
Published: June 2017

A 19‐cohort bioeconomic model is developed for the southern bluefin tuna fishery. The fish are long‐lived and highly migratory. They are harvested as juveniles by Australia and Japan in Australian waters, and as adults by Japan on the high seas. The potential for conflict between Australian and Japanese fleets therefore exists in the exploitation of the fishery. The model is used to compare Japanese and Australian social rents and harvest levels through time under joint maximization, and under duopoly.
EFFICIENT MANAGEMENT OF GROUNDWATER QUALITY
Authors: Zeitouni Naomi
Published: June 2017

This work develops a theoretical framework that considers the pollution transport in groundwater in an optimization of social benefits from a groundwater resource, and provides a spatial and temporal allocation of the use of contaminating inputs. A space dependent social cost function is constructed, taking into account factors such as the wells' locations and emitting firms' locations, in addition to profits from polluting activities. The social optimization is formulated using the pollution concentrations as state variables and the pollution transport as state dynamics. This optimization yields a spatially differentiated shadow price which leads to optimal policy which is nonuniform in general, and uniform only for special cases.
BOOK REVIEW
Authors: Hastings Alan
Published: June 2017

BIOLOGICAL DELAY SYSTEMS: LINEAR STABILITY THEORY, N. MacDonald, Cambridge University Press, Cambridge and New York, 1989
A UNIFIED APPROACH TO MULTISPECIES MODELING
Authors: Getz Wayne M.
Published: June 2017

Ordinary differential equation (ODE) population models have been pivotal in the development of ecological theory. Here I propose an ODE formulation that is biologically more consistent than previous formulations and applies equally well to modeling predation, competition, mutualism, and combinations of all three in complex food webs. The formulation is based on two principles: I. The rate at which a population consumes resources is determined by a functional response that includes the effects of both consumer satiation and intraspecific interference competition; II. The intrinsic growth rate of a population, independent of trophic level, is a saturating function of resources consumed and approaches minus infinity as the rate of resources consumption approaches zero. After deriving a general model, I consider specific forms for the consumption and growth functions associated with Principles I and II. I use these functions to derive a generalized logistic growth model, in the process expressing the logistic growth and carrying capacity parameters in terms of the biologically more intuitive consumption and intrinsic growth function parameters. I then go on to consider specific prey‐predator, trophic stack, consumer‐resource, competition, and mutualism models and, where appropriate, contrast them with models that have been obtained by direct modification of the Lotka‐Volterra approach to multispecies analysis.
STOCHASTIC PRICE MODELS AND OPTIMAL TREE CUTTING: RESULTS FOR LOBLOLLY PINE
Authors: Haight Robert G. , Holmes Thomas P.
Published: June 2017

An empirical investigation of stumpage price models and optimal harvest policies is conducted for loblolly pine plantations in the southeastern United States. The stationarity of monthly and quarterly series of sawtimber prices is analyzed using a unit root test. The statistical evidence supports stationary autoregressive models for the monthly series and for the quarterly series of opening month prices. In contrast, the evidence supports a non‐stationary random walk model for the quarterly series of average prices. This conflicting result is likely an artifact of price averaging. The properties of these series significantly affect the forms of optimal price‐dependent harvest rules and expected returns. Further, the results have implications for conclusions about market efficiency and the performance of a fixed rotation age.
ENVIRONMENTAL POLLUTION AND UNILATERAL CONTROL IN AN OPEN ECONOMY
Authors: Batabyal Amitrajeet A.
Published: June 2017

In this paper we study two questions in environmental economics. First, within the context of a simple 2 × 2 × 2 static general equilibrium model, we seek to determine the conditions under which environmental policy, pursued unilaterally by a large country will make that country worse off. The empirical dimension of this question is stressed, and the key parameters which are germane to any policy discussion regarding this issue are identified. Second, we study—once again from the perspective of a large country—the possibility of using the domestic tax structure optimally to attain environmental policy objectives. Keeping the empirical dimension of the question in mind, we show how to compute optimal externality correcting taxes. We then briefly focus on the links between our stylized analytical model and the applied general equilibrium models currently being developed to study the effects of environmental policy quantitatively.
A MODEL OF THE ENZOOTIOLOGY OF LYME DISEASE IN THE ATLANTIC NORTHEAST OF THE UNITED STATES
Authors: Porco Travis C.
Published: June 2017

A mathematical model is presented for the dynamics of the rate of infection of the Lyme disease vector tick Ixodes dammini (Acari: Ixodidae) by the spirochete Borrelia burgdorferi, in the Atlantic Northeast of the United States. According to this model, moderate reductions in the abundance of white‐tailed deer Odocoileus virginianus may either decrease or increase the spirochete infection rate in ticks, provided the deer are not reservoir hosts for Lyme disease. Expressions for the basic reproductive rate of the disease are computed analytically for special cases, and it is shown that as the basic reproductive rate increases, a proportional reduction in the tick population produces a smaller proportional reduction in the infection rate, so that vector control is less effective far above the threshold. The model also shows that control of the mouse reservoir hosts Peromyscus leucopus could reduce the infection rate if the survivorship of juvenile stages of ticks were reduced as a consequence. If the survivorship of juvenile stages does not decline as the rodent population is reduced, then rodent reduction can increase the spirochete infection rate in the ticks.
AN ITERATIVE MULTILEVEL APPROACH TO NATURAL RESOURCE OPTIMIZATION: A TEST CASE
Authors: Hof John , Kent Brian , Baltic Tony
Published: June 2017

Forest planners face a dilemma. On the one hand, they desire more detail than they currently have in their planning optimization models, and on the other hand, these models are already extremely large and complex. This sort of problem is common in other natural resource management situations as well. This paper investigates an iterative multilevel approach that would allow districts within the forest to have models approaching the size and complexity of current forest models, but still approximate a forest‐level optimum. A specific procedure based on equating shadow prices across districts is developed and tested with a case example where a global optimum is determinable as a standard of comparison. The procedure shows promise, but difficulties in recognizing optimality are indicated.
A DISTRIBUTED PARAMETER CONTROL SYSTEMS APPROACH TO THE ANALYSIS OF WATER ALLOCATION
Authors: Hsu Shih‐Hsun , Griffin Ronald C.
Published: June 2017

The optimal diversion and consumption of water is examined in a framework acknowledging both diversionary water demands and instream water demands. Return flow relationships among a basin's water users recommends that optimization be conducted over time and space domains jointly. The distributed parameter control methodology is employed to satisfy this need in a generalized model. Results demonstrate the power of the method and identify how attention to instream demands influences optimal water use by the basin's diverters.
OPPORTUNITY COSTS OF FEDERAL LAND‐USE RESTRICTIONS FOR U.S. COAL MARKETS
Authors: Watson W. D.
Published: June 2017

U.S. federal government land‐use restrictions limit access to high‐quality, low‐cost coal on federal lands in the western U.S. The main purpose of these limits is to protect the environment. A substantial amount of U.S. coal resources has been set aside, about 67 billion tons, which represents 27% of total U.S. surface‐minable coal. Debate has focused on the environmental benefits attained by the land‐use restrictions; little effort has gone into the explicit quantification of opportunity costs. To help fill that gap, this analysis examines the long‐term effects that these restrictions could have on the national cost of meeting future coal demands, including impacts on regional patterns of coal availability and production.
A RAPID APPROXIMATION FOR PREDICTING THE HYDROCARBON DISCOVERY RATE: PART 2. IMPROVING THE ACCURACY
Authors: Ninpong R. , Power M. , Fuller J.D.
Published: June 2017

In Part 1 of this paper, we noted the systematic errors in the estimates of means and standard deviations produced by a rapid approximation applied to a model of hydrocarbon discovery. In Part 2, we apply regression to predict the approximation errors, as functions of model parameters and approximation output. With the regression model, we can correct much of the error in the approximation, as we illustrate with data from the Nisku‐Shelf play of western Canada.
A DISCRETE AGE STRUCTURED SI MODEL OF TRACHEAL MITE (Acarapis woodi (RENNIE)) INFESTATION OF HONEY BEES (Apis mellifera L.) AT THE COLONY LEVEL
Authors: Mangum W.A.
Published: June 2017

This paper presents a discrete age structured SI model of tracheal mite (Acarapis woodi (Rennie)) infestation of honey bees (Apis mellifera L.) at the colony level. The model describes the elevated honey bee attrition during winter and predicts that winter brood rearing should promote colony survival by decreasing the colony's infestation and increasing the colony's population. The model also predicts that swarming and the artificial removal of part of the colony's forager honey bees should reduce the colony's infestation level.
SECOND BEST TAXES AND QUOTAS IN NITROGEN REGULATION
Authors: Feinerman Eli , Choi E. Kwan
Published: June 2017

This paper investigates second best policies to regulate nitrogen leaching. When the policy maker controls the total nitrogen use, an overall tax is superior to an action equivalent overall quota. When the goal is to regulate the expected level of nitrogen leaching, expected profit of a risk neutral farmer is greater under an overall tax than under an overall quota under a reasonable condition.

The welfare ranking of action equivalent taxes and quotas for a risk averse farmer is generally ambiguous. In the numerical analyses, overall taxes turned out to be superior to overall quotas with both targets, despite a very high value of absolute risk aversion, 0.01. These results suggest that an overall tax is probably a superior policy to an overall quota to regulate expected total nitrogen use or expected nitrogen leaching for risk neutral and most of risk averse farmers.
GAME‐THEORETIC RESOURCE MODELING
Authors: Mesterton‐Gibbons Michael
Published: June 2017

Games—mathematical models of strategic interaction—embrace a multitude of disciplines, in each of which they form a largely separate field of study with its own traditions and priorities. Game‐theoretic resource modeling concerns itself primarily with strategic aspects of externalities arising from joint use of the commons, although it also deals with externalities of privately owned resources and with questions of fairness in allocating shared resource costs. This essay surveys resource games—in fisheries, forestry, water resources and environmental regulation—within a novel unifying framework, assesses their contribution to current understanding of resource issues, and indicates their promise for the future.
THE PROBLEM OF NONMALLEABLE CAPITAL REVISITED; A STUDY OF THE PACIFIC HALIBUT FISHERY
Authors: Schellberg Thomas
Published: June 2017

It has been suggested in the literature on commercial fisheries that fishing capital may be nonmalleable, i.e., not easily moved from one fleet to another, and that the socially optimal rate of capitalization of boats may depend on the degree of malleability (irreversibility) of the fishing fleet. To find out how irreversibility affects optimal regulation, two of the many possible regulatory tools, unallocated quotas and catch taxes, are examined. These optimal policies are derived, alternatively assuming malleable and nonmalleable fishing capital. Using a simulation of the Pacific halibut fishery, the results obtainable through catch quotas are shown to be inferior to those obtainable through taxes, but that the degree of malleability of capital has a surprisingly small impact on policy. A sensitivity analysis is performed, rerunning these simulations over a variety of parameter values. The previous results are largely borne out.
FORECASTING MINERAL SUPPLY FROM MINERAL RENT DATA
Authors: Dale Larry L. , Williams Nancy A.
Published: June 2017

An optimal control model of exhaustible resources is used to clarify the long run relationship between mineral rent and depletion cost at the industry level. A standard first order condition of the time rate of change of rents is reformulated to reveal that rent data may be used to help forecast the rise in extraction costs resulting from resource depletion.

This application of the theory of exhaustible resources is illustrated using historical mineral industry rent and extraction cost data. A forecast of U.S. coal extraction costs, following the method proposed in this paper, suggests that future rates of extraction cost increases will be similar to rates experienced in the past.
THE DIFFUSION OF RESOURCE‐QUALITY‐AUGMENTING TECHNOLOGIES: OUTPUT SUPPLY AND INPUT DEMAND EFFECTS
Authors: Caswell Margriet F. , Zilberman David , Casterline Gary
Published: June 2017

This paper develops a model that shows that the adoption of a modern conservation technology is a gradual process in which dynamic patterns are determined by variation in resource quality among producers, improvements in equipment, and learning. The dynamics of technological changes are reflected in the cyclical patterns of production and resource use. A numerical example simulates adoption rates of modern irrigation technologies using California data and shows that rate of adoption is an S‐shaped function of time and that water use and output are cyclical.
TWO INFORMATIONAL ISSUES IN RESOURCE MODELING
Authors: Berck Peter
Published: June 2017

Neither the pattern of future resource demand nor the level of available supply is known with any great certainty. This paper quantifies the uncertainty in key demand and supply elements for the California Redwood Industry. The paper then shows that the loss to imperfect information about available supply is not very large.
BOOK REVIEW
Authors: Noble Chris
Published: June 2017

Models in Biology: Mathematics, Statistics and Computing, D. Brown, P. Rothery, John Wiley & Sons, Ltd., Chichester, 1993, xix +688 pp.
BOOK REVIEW
Authors: Hilborn Ray
Published: June 2017

Proceedings of the International Symposium on Management Strategies for Exploited Fish Populations Alaska Sea Grant College Program Report No. 93‐02 University of Alaska, Fairbanks, G. Kruse, D.M. Eggers, R.J. Marasco, C. Pautzke, T.J. Quinn II, eds., 1993, viii + 825 pp., price $30.00
BOOK REVIEW
Authors: Shelton Peter A.
Published: June 2017

Fishing for Truth: A Sociological Analysis of Northern Cod Stock Assessments from 1977 to 1990, A.C. Finlayson, Published by the Institute of Social and Economic Research, Memorial University of Newfoundland, 1994, 176 pp., ISBN 0‐919666‐79‐5
COMPUTING OPTIMAL ALLOCATIONS FOR DISCRETE‐TIME NONLINEAR NATURAL RESOURCE MODELS
Authors: Rowse John
Published: June 2017

Nonlinear programming (NLP) offers many advantages for formulating and solving discrete‐time nonlinear natural resource models. Not all natural resource analysts are aware of these advantages, however, and in this paper NLP approaches are discussed for a class of renewable resource models recently addressed in the literature using a current‐period decision rule approximation method, a class of nonrenewable resource models recently solved by first identifying the terminal extraction period, and related nonrenewable resource models. NLP can solve dynamic models ranging in size from small pedagogically‐oriented theoretical models to large‐scale policy evaluation models exhibiting many real‐world complications.
SEQUENTIAL FISHING: COOPERATIVE AND NON‐COOPERATIVE EQUILIBRIA
Authors: Hannesson Röugnvaldur
Published: June 2017

Two agents control the areas in which a migrating fish stock is located. The harvesting is sequential. The stock available to Agent 1 depends on the growth of the stock, which in turn depends on the amount left after harvesting by Agent 2. The stock available to Agent 2 is the quantity left after harvesting by Agent 1. Each agent fishes down the stock in each period to an “abandonment level” deemed appropriate. The problem is analyzed as a noncooperative versus cooperative, repeated game with an infinite time horizon. In the noncooperative solution, both agents will harvest the stock if the unit cost of Agent 2 is not too much higher than the unit cost of Agent 1. A cooperative solution supported by a threat to revert to the noncooperative solution if deviation occurs implies greater differences in unit costs at which both agents will harvest the stock. The problem is illustrated by a simple, numerical example.
SIMULATING COST‐EFFECTIVE WETLANDS RESERVES: A COMPARISON OF POSITIVE AND NORMATIVE APPROACHES
Authors: Parks Peter J. , Kramer Randall A. , Heimlich Ralph E.
Published: June 2017

A conceptual model of farmer behavior is used to develop analytical expressions for the costs of wetland policies in the United States. An empirical study based on the model compares normative and positive cost estimates for accomplishing a specific policy and shows that these two modeling strategies yield very different cost estimates from the same basic data. Because models such as these are frequently used to support budget requests for government programs, the choice of modeling strategy can influence whether program goals can be accomplished with the funds requested.
THE CONSERVATION AND MANAGEMENT OF HIGH SEAS FISHERY RESOURCES UNDER THE NEW LAW OF THE SEA
Authors: Kaitala Veijo , Munro Gordon
Published: June 2017

The Agreement, arising from the recently concluded U.N. Conference on Straddling Fish Stocks and Highly Migratory Fish Stocks, calls for the management of these transboundary resources to be undertaken through regional fisheries management organizations. This paper represents a first attempt to analyze the optimal economic management of straddling/highly migratory stocks under the to‐be‐established regional organizations. Dynamic game theory, commonly used in analyzing the management of “shared” fishery resources, is brought to bear.

An obvious question to be raised is whether the analysis applied to “shared” fish stocks management is sufficient for the purpose of examining the management of straddling/highly migratory fish stocks. The analysis is not sufficient for the purpose of examining the cooperative management of straddling/highly migratory fish stocks, because, in contrast to “shared” fish stock management, there is no guarantee that the number and nature of joint exploiters of the resource, in the aforementioned regional organization, will be constant through time. It is the existence of what is termed the “New Member Problem” which most clearly distinguishes the management of straddling/highly migratory fish stocks from the management of “shared” fish stocks. The paper discusses several approaches to addressing the “New Member Problem.”
HARVESTING STRATEGIES FOR A MIGRATORY FISH STOCK BASED ON A MODEL WITH UNCERTAINTY
Authors: Lee C.S. , Goh B.S.
Published: June 2017

We model a species of fish with breeding ground protected, and harvesting is carried out in an adjacent area. There is migration of fish from the breeding ground to the adjacent area. We demonstrate that in the presence of bounded uncertain disturbances, the strategy of harvesting the fish biomass at the maximum sustainable yield level is indeed optimal in the long term consideration.
ENVIRONMENTAL AND FINANCIAL SUSTAINABILITY OF FOREST MANAGEMENT PRACTICES
Authors: Armstrong Glen W. , Novak Frank S. , Adamowicz Wiktor L.
Published: June 2017

One of the guiding themes for forest management policy throughout much of North America is sustained yield. The basic premise behind this theme is that a constant or nondeclining flow of services from the forest is socially desirable. Unfortunately, the act of capturing the benefits of this service (timber harvesting) often has detrimental effects on the timber‐productive capacity of a forest site. This paper presents a dynamic program that is used to determine the optimal harvest system choice for a timber stand described by average piece size, stand density, a measure of site quality, and stumpage value. The harvest systems are defined by logging costs, reforestation and rehabilitation costs, and the impact of the system on the productivity of the site.

An application of the model is presented for lodgepole pine in Alberta. We conclude that, at high discount rates, soil conservation is not economically rational. At lower discount rates, some degree of soil conservation is desirable on the more productive sites. At lower discount rates, there also appears to be an incentive for more intensive forest management. Limitations on acceptable harvest practices can have a large impact on optimal rotation age and the volume harvested. There is a large opportunity cost resulting from a requirement for sustainable volume production because of the impact of harvesting on soil productivity.