bluuebunny/crossref_metadata_2025 huggingface dataset:
Reinterpreting maximum entropy in ecology: a null hypothesis constrained by ecological mechanism
Authors: O’Dwyer James P. , Rominger Andrew , Xiao Xiao
Published: June 2017

Simplified mechanistic models in ecology have been criticised for the fact that a good fit to data does not imply the mechanism is true: pattern does not equal process. In parallel, the maximum entropy principle (MaxEnt) has been applied in ecology to make predictions constrained by just a handful of state variables, like total abundance or species richness. But an outstanding question remains: what principle tells us which state variables to constrain? Here we attempt to solve both problems simultaneously, by translating a given set of mechanisms into the state variables to be used in MaxEnt, and then using this MaxEnt theory as a null model against which to compare mechanistic predictions. In particular, we identify the sufficient statistics needed to parametrise a given mechanistic model from data and use them as MaxEnt constraints. Our approach isolates exactly what mechanism is telling us over and above the state variables alone.
Effect of pH on dentin protease inactivation by carbodiimide
Authors: Seseogullari‐Dirihan Roda , Mutluay Mustafa M. , Tjäderhane Leo , Breschi Lorenzo , Pashley David H. , Tezvergil‐Mutluay Arzu
Published: June 2017

A water‐soluble crosslinking agent, 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide (EDC), has been used as a pretreatment of acid‐etched dentin to inactivate matrix‐bound endogenous dentin proteases. The aim of this study was to evaluate the effect of pH on the inactivation capacity of EDC. Demineralized dentin beams (1 × 2 × 6 mm) were divided into six groups (n = 8 per group). Then, EDC (0.3 M) was solubilized in distilled water with pH of 2, 4, 6, 7, 9, or 11. Control EDC was solubilized in 0.1 M 2‐(N‐morpholino) ethanesulfonic acid (MES) buffer and its pH was adjusted to 6. The dentin beams were pretreated for 1 min with EDC at each pH or with EDC in MES buffer at pH 6.0 and then incubated in 1 ml of simulated body fluid (pH 7.2) for 1, 3, 7, or 14 d. Untreated beams served as controls. At each study time‐point, the dry mass of dentin beams was assessed and the incubation media were analyzed for carboxyterminal telopeptide of type‐I collagen (ICTP) and C‐terminal telopeptide of type I collagen (CTX) using specific ELISAs. Data were subjected to repeat‐measures anova. The results of the study indicated that specimens pretreated with EDC in MES buffer showed the lowest collagen degradation in terms of mass loss and release of telopeptides, while specimens pretreated in alkaline media showed the highest collagen degradation. This study indicates that the pH of the EDC solution plays an important role in the stability of dentin protease inactivation.
Clinical association between chronic periodontitis and the leukocyte extravasation inhibitors developmental endothelial locus‐1 and pentraxin‐3
Authors: Folwaczny Matthias , Karnesi Evangelia , Berger Tamara , Paschos Ekaterini
Published: June 2017

This clinical study aimed to determine whether periodontal disease is associated with expression of developmental endothelial locus‐1 (Del‐1) and pentraxin‐3 (PTX‐3), endogenous inhibitors of leukocyte extravasation in humans. Expression of DEL1, PTX3, interleukin‐17A (IL17A), and lymphocyte function‐associated antigen‐1 (LFA1) was determined, using RT‐PCR and melting curve analysis, in biopsies of gingival tissues from 95 patients: 42 with moderate periodontitis; 40 with severe periodontitis; and 13 healthy controls. Relative expression of DEL1 and PTX3 was statistically significantly weaker in patients with periodontitis than in the control subjects. On the contrary, both IL17A and LFA1 showed statistically significant stronger expression in patients with periodontitis than in healthy controls. Correlation analysis, performed using Spearman's test, showed that expression of DEL1 was statistically significantly linked to periodontitis (ρ = −0.103) and to age (ρ = −0.134), but not to the gender of the patient, and that expression of PTX3 was significantly correlated with periodontitis (ρ = −0.354). Expression of neutrophil extravasation inhibitors DEL1 and PTX3 show significant, but weak, association with the clinical manifestation of chronic periodontitis.
Oral disorders, saliva secretion, and oral health‐related quality of life in patients with primary Sjögren's syndrome
Authors: Rusthen Shermin , Young Alix , Herlofson Bente B. , Aqrawi Lara A. , Rykke Morten , Hove Lene H. , Palm Øyvind , Jensen Janicke L. , Singh Preet B.
Published: June 2017

Chemosensory function, burning sensations in the tongue (BST), halitosis, saliva secretion, and oral health‐related quality of life (OHRQoL) were investigated in patients with primary Sjögren's syndrome (pSS). In 31 patients with pSS and 33 controls, olfactory and gustatory functions were evaluated. Self‐reported complaints of dysgeusia, BST, and halitosis were recorded. Saliva secretion rates were measured and OHRQoL was assessed using the short‐form Oral Health Impact Profile (OHIP‐14). Patients had significantly lower olfactory (8.8 ± 3.5 vs. 10.7 ± 1.2) and gustatory (18.9 ± 7.1 vs. 25.4 ± 4.3) scores than controls, and significantly more patients complained of dysgeusia (58.1% vs. 0%), BST (54.8% vs. 6.1%), and halitosis (41.9% vs. 0%). A significantly greater proportion of patients with pSS had ageusia (19% vs. 0%), hypogeusia (32% vs. 12%), anosmia (13% vs. 0%), or hyposmia (29% vs. 9%). Significantly lower saliva secretion rates (ml min−1) were observed in patients with pSS for stimulated (0.62 ± 0.40 vs. 1.57 ± 0.71) and unstimulated (0.08 ± 0.07 vs. 0.29 ± 0.17) saliva. The mean OHIP‐14 score was significantly higher in patients with pSS (16.2 ± 10.8 vs. 2.7 ± 3.1) and was positively correlated with dysgeusia, BST, and halitosis. In conclusion, patients with pSS reported higher occurrence of dysgeusia, BST, and halitosis, and demonstrated relatively impaired chemosensory and salivary functions. The patients’ poorer OHRQoL was associated with dysgeusia, BST, and halitosis.
Assessing global patterns in mammalian carnivore occupancy and richness by integrating local camera trap surveys
Authors: Rich Lindsey N. , Davis Courtney L. , Farris Zach J. , Miller David A. W. , Tucker Jody M. , Hamel Sandra , Farhadinia Mohammad S. , Steenweg Robin , Di Bitetti Mario S. , Thapa Kanchan , Kane Mamadou D. , Sunarto S. , Robinson Nathaniel P. , Paviolo Agustín , Cruz Paula , Martins Quinton , Gholikhani Navid , Taktehrani Ateih , Whittington Jesse , Widodo Febri A. , Yoccoz Nigel G. , Wultsch Claudia , Harmsen Bart J. , Kelly Marcella J.
Published: June 2017

Aim

Biodiversity loss is a major driver of ecosystem change, yet the ecological data required to detect and mitigate losses are often lacking. Recently, camera trap surveys have been suggested as a method for sampling local wildlife communities, because these observations can be collated into a global monitoring network. To demonstrate the potential of camera traps for global monitoring, we assembled data from multiple local camera trap surveys to evaluate the interchange between fine‐ and broad‐scale processes impacting mammalian carnivore communities.

Location

Argentina, Belize, Botswana, Canada, Indonesia, Iran, Madagascar, Nepal, Norway, Senegal, South Africa, and the U.S.A.

Methods

We gathered camera trap data, totalling > 100,000 trap nights, from across five continents. To analyse local and species‐specific responses to anthropogenic and environmental variables, we fitted multispecies occurrence models to each study area. To analyse global‐level responses, we then fitted a multispecies, multi‐area occurrence model.

Results

We recorded 4,805 detections of 96 mammalian carnivore species photographed across 1,714 camera stations located in 12 countries. At the global level, our models revealed that carnivore richness and occupancy within study areas was positively associated with prey availability. Occupancy within study areas also tended to increase with greater protection and greater distances to roads. The strength of these relationships, however, differed among countries.

Main conclusions

We developed a research framework for leveraging global camera trap data to evaluate patterns of mammalian carnivore occurrence and richness across multiple spatial scales. Our research highlights the importance of intact prey populations and protected areas in conserving carnivore communities. Our research also highlights the potential of camera traps for monitoring wildlife communities and provides a case study for how this can be achieved on a global scale. We encourage greater integration and standardization among camera trap studies worldwide, which would help inform effective conservation planning for wildlife populations both locally and globally.
Linking species interactions with phylogenetic and functional distance in European bird assemblages at broad spatial scales
Authors: Mönkkönen Mikko , Devictor Vincent , Forsman Jukka T. , Lehikoinen Aleksi , Elo Merja
Published: June 2017

Aim

Understanding the relative contribution of different species interactions in shaping community assembly has been a pivotal aim in community ecology. Biotic interactions are acknowledged to be important at local scales, although their signal is assumed to weaken over longer distances. We examine the relationship between positive, neutral and negative pairwise bird abundance distributions and the phylogenetic and functional distance between these pairs after first controlling for habitat associations.

Location

France and Finland.

Time period

1984 to 2011 (Finland), 2001 to 2012 (France).

Major Taxa studied

Birds.

Methods

We used results from French and Finnish land bird monitoring programmes, from which we created three independent datasets (French forests, French farmlands and Finnish forests). Separately for the three datasets, we fitted linear mixed‐effects models for pairwise abundance values across years per point count station to infer the association between all common species pairs, while controlling for geographical distribution and habitat associations, and saved pairwise regression coefficients for further analyses. We used a null model approach to infer whether the observed associations (effect sizes) differ from random. Finally, using quantile regression, we analysed the relationships between functional dissimilarity/phylogenetic distance and effect sizes.

Results

Our results show both negative and positive species interactions, although negative interactions were twice as common as positive interactions. Closely related species were more likely to show strong associations, both negative and positive, than more distant species across broad spatial scales. For functional dissimilarity, the results varied across datasets.

Main conclusions

Our results emphasize the potential of functional and phylogenetic proximity in generating both negative and positive species associations, which can produce pervasive patterns from local to geographical scales. Future assembly studies should refrain from strict dichotomies, such as compensatory dynamics versus environmental forcing, and instead consider the possibility of positive interactions.
Uneasiness in culture, or negotiating the sublime distances towards the big Other
Authors: Kingsbury Paul
Published: June 2017

This paper engages Slavoj Žižek's thesis that people's integration into a dominant culture requires successfully negotiating certain “distances” towards what Jacques Lacan called the “big Other,” that is, a nonexistent locus that subtly guides symbolic rules, conventions, and mandates. My main goal here is to illustrate how Žižek's conceptualizations of distance and the big Other can further our geographical theorizations of culture, especially in terms of Sigmund Freud's notion of the “uneasiness in culture.” I explore Žižek's identification of three modes of distanciation towards the big Other—“inherent transgression”, “empty gesture,” and “fetishistic disavowal,” which abound in uneasiness because they are sublime, that is, demarcated by virtuality and unfathomability. I also discuss how the demise of the big Other's authority has produced new spaces of cultural uneasiness that can be usefully understood in terms of increased interactions between everyday microcultures.
‘AUSSERORDENTLICH BEWEGLICH UND NICHT ZU FANGEN’: ELUSIVENESS IN KAFKA
Authors: Speirs Ronald
Published: June 2017

This paper takes as its starting point the interpretive puzzles presented to the reader by the highly mobile and elusive phenomenon ‘Odradek’ in Kafka's ‘Die Sorge des Hausvaters’. It goes on to consider, on the one hand, Kafka's efforts in his aphorisms to build a metaphysical scheme centred on movement as a key feature of human existence, and, on the other hand, various elements in Kafka's writing which elude containment within that metaphysical construct.

Dieser kurze Beitrag beginnt mit einer Betrachtung der rätselhaften, äußerst beweglichen und nicht zu fangenden Figur Odradek in der Erzählung ‘Die Sorge des Hausvaters’. Davon ausgehend untersucht der Artikel auf der einen Seite Kafkas Bemühungen, eine metaphysische Interpretation des menschlichen Lebens aufzubauen, bei der die Bewegung eine Schlüsselrolle spielt; auf der anderen Seite richtet er die Aufmerksamkeit auf eine Reihe von Stellen bei Kafka, die sich weigern, in jenem metaphysischen Bau einfangen zu lassen.
Review: Prevalence and dynamics of Helicobacter pylori infection during childhood
Authors: Zabala Torrres Beatriz , Lucero Yalda , Lagomarcino Anne J. , Orellana‐Manzano Andrea , George Sergio , Torres Juan P. , O'Ryan Miguel
Published: June 2017

Introduction

Long‐term persistent Helicobacter pylori infection has been associated with ulceropeptic disease and gastric cancer. Although H. pylori is predominantly acquired early in life, a clear understanding of infection dynamics during childhood has been obfuscated by the diversity of populations evaluated, study designs, and methods used.

Aim

Update understanding of true prevalence of H. pylori infection during childhood, based on a critical analysis of the literature published in the past 5 years.

Methods

Comprehensive review and meta‐analysis of original studies published from 2011 to 2016.

Results

A MEDLINE®/PubMed® search on May 1, 2016, using the terms pylori and children, and subsequent exclusion, based on abstract review using predefined criteria, resulted in 261 citations. An Embase® search with the same criteria added an additional 8 citations. In healthy children, meta‐analysis estimated an overall seroprevalence rate of 33% (95% CI: 27%‐38%). Seven healthy cohort studies using noninvasive direct detection methods showed infection prevalence estimates ranging from 20% to 50% in children ≤5 and 38% to 79% in children >5 years. The probability of infection persistence after a first positive sample ranged from 49% to 95%. Model estimates of cross‐sectional direct detection studies in asymptomatic children indicated a prevalence of 37% (95% CI: 30%‐44%). Seroprevalence, but not direct detection rates increased with age; both decreased with increasing income. The model estimate based on cross‐sectional studies in symptomatic children was 39% (95% CI: 35%‐43%).

Conclusions

The prevalence of H. pylori infection varied widely in the studies included here; nevertheless, model estimates by detection type were similar, suggesting that overall, one‐third of children worldwide are or have been infected. The few cohort and longitudinal studies available show variability, but most studies, show infection rates over 30%. Rather surprisingly, overall infection prevalence in symptomatic children was only slightly higher, around 40%. Studies including only one positive stool sample should be interpreted with caution as spontaneous clearance can occur.
Benign vascular lesions of the breast diagnosed by core needle biopsy do not require excision
Authors: Sebastiano Christopher , Gennaro Lucas , Brogi Edi , Morris Elizabeth , Bowser Zenica L , Antonescu Cristina R , Pareja Fresia , Brennan Sandra , Murray Melissa P
Published: June 2017

Aims

Surgical excision of all benign vascular lesions of the breast identified by core needle biopsy has been recommended in the past to rule out a more serious lesion. In this study we investigated the clinical, radiological and pathological findings in patients diagnosed with a benign vascular lesion at our institution to assess whether excision may be spared for lesions without atypia.

Methods and results

We searched the electronic medical record for patients with a vascular lesion of the breast diagnosed between 2000 and 2015. The study population consisted of 84 patients, 83 females and one male. The index diagnoses included 76 benign vascular lesions, five vascular lesions with cytological atypia and three angiosarcomas. A radiologist reviewed all pre‐ and post‐biopsy imaging studies; all cases had concordant radiological and pathological findings. Based on radiological and histological correlation, the vascular lesion accounted for the radiological target in 40 (48%) cases and was deemed an incidental finding in 44 (52%). Seven of 32 (22%) targeted and 10 of 44 (23%) incidental benign vascular lesions underwent surgical excision; there were no upgrades at excision. No recurrences or clinical events were observed in patients with a targeted or incidental benign vascular lesion with a median follow‐up of 39 months and 40.6 months, respectively.

Conclusion

Our data suggest that benign vascular lesions diagnosed on core biopsy with concordant radiological and pathological findings do not warrant surgical excision.
Controlling the microstructure of lyophilized porous biocomposites by the addition of ZnO‐doped bioglass
Authors: Ciołek Lidia , Biernat Monika , Jaegermann Zbigniew , Tymowicz‐Grzyb Paulina , Taźbierski Piotr , Jastrzębska Agnieszka , Olszyna Andrzej
Published: June 2017

The study presents the results of the study on porous composite biomaterials obtained using lyophilization method based on polymer solutions: chitosan solution, sodium alginate solution, or polylactide solution, and ZnO‐doped bioglass from CaO‐SiO2‐P2O5 system. The properties of zinc ions were used, which have bactericidal, immune‐stimulating, and tissue‐regenerating functions in the organism. The effects of the polymer type, granulation, and bioglass amount, as well as the amount of solvent on composite microstructure, were studied. SEM‐EDS technique was used to visualize and describe the surface results occurring after incubation of composite in the Simulated Body Fluid (SBF). The selected method of preparation, used substrates, and the process conditions resulted in porous composites of the open, connected pore structure. It was proved that composite microstructure may be controlled by the appropriately selected amount of bioglass in relation to the polymer and its appropriate grain sizes. The morphology of the obtained composites is also affected by the amount of the solvent in lyophilizated dispersions. It was proved that bioactivity in composite material is induced by bioglass because after SBF incubation the surface layer is enriched with Ca and P, what may lead to a gradual formation of apatite layer. The obtained results enabled selection of the composites for further in vitro studies concerning cytotoxicity and antibacterial activity.
Recomposition and levelling of consumption expenditures across four economic shocks in Russia, 1994–2014
Authors: Kotelnikova Zoya , Radaev Vadim
Published: June 2017

The authors examine the changes in the level and composition of consumption expenditures and their associations with household per capita incomes across the four different economic shocks that Russia has experienced since 1994. Data were collected from a nationally representative annual panel survey of households between 1994 and 2014, supplemented by the Federal State Statistics Service source. Four hypotheses on the relationship between per capita income and consumption, the composition of cutbacks, a levelling of expenditures among income groups, and the stability of the pattern of consumer response to economic shocks are proposed. The data demonstrate that consumption expenditures on food, non‐food, and services decreased together with per capita income during the four economic shocks. Only a few examples of significant smoothing effects were found. All income groups recomposed their expenditures to maintain consumption of necessities. The high‐income group reduced a higher proportion of expenditures on food and services, implying that economic shocks produce a temporary levelling effect on the living standards of different income groups. A relatively stable pattern of consumer responses to economic shocks was revealed, despite these shocks’ divergence; this pattern implies a temporary economization and simplification of expenditures with a fast return to pre‐crisis spending once the crisis is over.
Coping with crises: Consumption and social resilience on markets
Authors: Koos Sebastian , Vihalemm Triin , Keller Margit
Published: June 2017

Crises, especially economic crises are an immanent element of modern market societies. While some research has been devoted to understanding the consequences of such crises on consumption, a systematic integrative approach to this problem is still missing. In this editorial we develop an encompassing model for the study of crises and consumption, to identify and connect the different elements important for understanding and explaining the relationship. Thereafter we present the papers of this special issue and discuss their contributions, based on the proposed framework. Suggestions for future research conclude the editorial.
Consumers’ evaluations of the efficiency of actions to improve environmental quality: A comparative study between Brazil and China
Authors: Mainardes Emerson Wagner , Yeh Tatiana , Leal Aureo
Published: June 2017

There is a gap in our knowledge about environmentally conscious consumers in industrialized economies and the desire to achieve sustainable economies. Given that most aspects of consumer behaviour are culture bound, this paper contributes by comparing consumers’ evaluations of the efficiency of actions to improve environmental quality in two of the most promising industrializing consumer societies: Brazil and China. The proposed conceptual framework includes environmental concerns, perceived consumer effectiveness, green attitudes, green behaviours and external motivators as constructs to explain the perception of efficient environmental support. Field research was conducted in Brazil with 1,149 respondents, and in China with 632 respondents to test the model. The results suggested that the belief that environmental quality can be improved is directly associated with consumers’ internal and external motivators. However, cultural traits drove important differences in the evaluation of the efficiency of such improvements. Specifically, Chinese people tended to rely on collective leadership to create the conditions necessary for improving environmental quality, while they remained concerned with the current status. In contrast, Brazilians accepted more personal responsibility for the results, although they face important constraints, such as the availability of products.
Maternal coping with the prospect of liver transplant among their school‐age children
Authors: Hiratsuka Katsuhiro , Nakamura Nobue , Sato Naho
Published: June 2017

The purpose of the current study was to describe the following: maternal coping with the prospect of becoming the living‐donor liver transplant for their child; the daily lives of school‐age children surviving biliary atresia with their native liver; and to explore the relationship between these individuals. Semistructured interviews were conducted with 6 school‐age children surviving biliary atresia with their native liver and their mothers. The interviews were conducted from June to August 2014, and a qualitative content analysis was used. Results showed that mothers realized a possible need for transplantation in the future, which contributes to emotional and practical uncertainties. The mothers coexisted with this uncertainty and preferred to use a buffering strategy. In contrast, the children did not consider their illness and future and did not adhere to a therapeutic regimen. It is suggested that living with uncertainty about the health and survival of their children is advantageous for mothers. However, problems related to the psychosocial aspect and child's adherence may occur in the future. In addition, problem‐solving coping strategies for mothers and the independence of chronically ill children with liver disease should be promoted.
Support surfaces in the prevention of pressure ulcers in surgical patients: An integrative review
Authors: de Oliveira Karoline Faria , Nascimento Kleiton Gonçalves , Nicolussi Adriana Cristina , Chavaglia Suzel Regina Ribeiro , de Araújo Cleudmar Amaral , Barbosa Maria Helena
Published: June 2017

Aim

To assess the scientific evidence about the types of support surfaces used in intraoperative surgical practice in the prevention of pressure ulcers due to surgical positioning.

Method

This is an integrative literature review. The electronic databases Cochrane, PubMed, Web of Science, Scopus, Lilacs, and CINAHL were used. The descriptors surgical patients, support surfaces, perioperative care, patient positioning, and pressure ulcer were used in the search strategy. Articles that addressed the use of support surfaces intraoperatively, published between 1990 and 2016, were selected. The PRISMA guidelines were used to structure the review.

Results

Of 18 evaluated studies, most were in English, followed by Portuguese and Spanish; most were performed by nurses. The most commonly cited support surfaces were viscoelastic polymer, micropulse mattresses, gel based mattresses, and foam devices.

Conclusion

There are gaps in knowledge regarding the most efficient support surfaces and the specifications of the products used to prevent pressure ulcers due to surgical positioning.
ON THE RELATIONSHIPS BETWEEN NATURAL AND HARVEST MORTALITIES OF THE MALLARD
Authors: Cohen Yosef
Published: June 2017

A discrete optimal control approach is used to show that the intensity of harvest of mallard populations in North America, at steady state, is sensitive to the strength of compensation between natural mortality and harvest mortality. Optimal harvest is less sensitive to changes in the natural mortality rate than to the interaction between natural and harvest mortalities. The management implications are: (1) if compensatory mortality operates, then more animals may be harvested without endangering the population, and (2) managers should pay particular attention to this mechanism in studying population dynamics.
PETROLEUM RESERVOIR MANAGEMENT: A RESERVOIR ECONOMIC APPROACH
Authors: Nystad Arild N.
Published: June 2017

This paper outlines an approach to investigate optimal depletion policies and economic policy issues for petroleum reservoirs.

We integrate an economic understanding into the more detailed engineering studies and petroleum reservoir depletion technology. The paper quantifies the microeconomic adjustment of the exploitation of different types of petroleum reservoirs including the impact which economic parameters have on the resource recovery.
BOOK REVIEW
Authors: Cushing J.M.
Published: June 2017

RENEWABLE NATURAL RESOURCES, J.A.J. Metz O. Diekmann, Springer Verlag, 1986
A STRONG ERGODIC THEOREM FOR SOME NONLINEAR MATRIX MODELS FOR THE DYNAMICS OF STRUCTURED POPULATIONS
Authors: Cushing J.M.
Published: June 2017

A general class of matrix difference equation models for the dynamics of discrete class structured populations in discrete time which possess a certain general type of nonlinearity introduced by Leslie for age‐structured populations is considered. Arbitrary structuring is allowed in that transitions between any two classes are permitted. It is shown that normalized class distributions for such nonlinear models globally approach a “stable class distribution” and thus possess a strong ergodic property exactly like that of the classical linear theory of demography. However, unlike in the linear theory according to which the total population size grows or dies exponentially, the dynamics of total population size in these nonlinear models are shown to be governed by a nonlinear, nonautonomous scalar difference equation. This difference equation is asymptotically autonomous, and theorems which relate the dynamics of total population size to those of this limiting equation are proved. Examples in which the results are applied to some nonlinear age‐structure models found in the literature are given.
A NEW LOOK AT WHOLE‐FOREST MODELING
Authors: Reed William J. , Errico Darrell
Published: June 2017

The harvest scheduling problem customarily known as Model II can be reformulated using a dynamic equation, and solved in two ways using linear programming. Viewing the problem in this way offers many insights and is convenient for deriving extensions to the basic problem. Extensions include the risk of catastrophic loss through fire, the problem of a changing land base, and the imposition of area constraints on the forest. An economic interpretation of certain dual variables in one of the solution methods is given. The mathematical equivalence of the standard Model II linear program, and the dynamic equation formulation, is demonstrated and the numerical efficiency of the various methods is examined for simple problems.
BOOK REVIEW
Authors: Clark Colin W.
Published: June 2017

APPLICATIONS OF CONTROL THEORY IN ECOLOGY, Edited by Y. Cohen, Springer Verlag Lecture Notes in Biomathematics
BOOK REVIEW
Authors: Derrick Bill
Published: June 2017

NONLINEAR DYNAMICS AND CHAOS, J.M.T. Thompson, H.B. Stewart, John Wiley and Sons, Chichester, England, 1986
LAND DEVELOPMENT AND WILDERNESS CONSERVATION POLICIES UNDER UNCERTAINTY: A SYNTHESIS
Authors: Clarke Harry R. , Reed William J.
Published: June 2017

The effects of uncertainty and irreversibility on land management are examined in an infinite horizon Arrow‐Fisher‐Henry conservation model with non‐linear land‐use welfare function which accounts for the possible role of breakthrough benefits stemming from the genetic resources of wilderness. The effects of uncertainty on optimality and certainty‐equivalent development strategies are examined. Crucially, “jump” decision rules are shown to be generally non‐optimal for managing wilderness areas.
BOOK REVIEW
Authors: Simberloff Daniel , Lawton Robert O.
Published: June 2017

WHY PRESERVE NATURAL VARIETY? B.G. Norton, Princeton University Press, 1987, Princeton, New Jersey
BOOK REVIEW
Authors: Biles Charles M.
Published: June 2017

A CONCRETE APPROACH TO MATHEMATICAL MODELLING, Michael Mesterton‐Gibbons, Addison‐Wesley, 1989, Reading, MA
BOOK REVIEW
Authors: Mullen Ashley
Published: June 2017

MATHEMATICAL BIOLOGY, J.D. Murray, Vol. 19, Biomathematics Series, Springer‐Verlag, New York‐Heidelberg‐Berlin, 1989
OPTIMAL TAXES FOR POLLUTION REGULATION: DYNAMIC, SPATIAL AND STOCHASTIC CHARACTERISTICS
Authors: Xepapadeas A.
Published: June 2017

The paper develops a model that incorporates the dynamic, spatial and stochastic aspects of environmental pollution. Conditions for optimal resource allocation between output production and pollution abatement processes are derived. Optimal emission (Pigouvian) taxes which may be used to efficiently regulate pollution in each region are determined. The pattern of emission taxes over time and their relative sizes among different regions are additionally explored with the help of a simplified numerical example.
FLOODING ON THE EEL RIVER: SYSTEM THEORETIC TIME SERIES, TRANSFER FUNCTION TIME SERIES, AND STRUCTURAL MODEL FORECASTS
Authors: Havenner Arthur , Tracy John
Published: June 2017

Three models are developed to forecast precipitation, stream flow, and suspended sediment load for the Middle Fork Eel River basin near Dos Rios, California. The models are a structural model, a transfer function time series model, and a multivariate time series model based on the ideas of linear systems theory. Monthly observations from 1961 through 1970 were used to specify and estimate the models, and their performance was evaluated using 36 observations from 1971 through 1973. The comparisons show that all of the models are able to simulate the general trend of the data fairly well but that the two time series models capture the detail better. The system theoretic time series model fares the best, providing consistently better forecasts of all three series. We conclude that this model would be valuable for use in planning water supply systems in the Eel River basin.
BOOK REVIEW
Authors: Kaitala Veijo
Published: June 2017

An Introduction to Game‐Theoretic Modeling, Michael Mesterson‐Gibbons, Addison‐Wesley, Redwood City, 1992, 237 pp.
INDIVIDUAL TRANSFERABLE QUOTAS AND PRODUCTION EXTERNALITIES IN A FISHERY
Authors: Boyce John R.
Published: June 2017

This paper determines the conditions under which an individual transferable quota (ITQ) system will cause fishermen to engage in cost‐decreasing, rather than cost‐increasing, competition. If there are production externalities (e.g., congestion or stock externalities) present, the market price of a quota will not be fully reflected in these externalities. Thus, fishermen will not fully internalize the externalities in their effort decisions. Even if there are no production externalities, an individual fisherman imposes costs on others under open access by removing a fish that was available to all fishermen. An ITQ system allows the individual who values that fish most to obtain the right to harvest the fish, so each fisherman must internalize the full social cost. Thus, an ITQ system is capable of solving the common property externality but not the production externalities in a fishery.
STABILITY OF THE PRICE REACTION FUNCTION WHEN THE CONSUMERS ANTICIPATE FUTURE PRICES
Authors: Wirl Franz
Published: June 2017

The hypothesis of the price reaction function‐prices change in dependence of capacity utilization‐is frequently applied to model OPEC's response to world oil market conditions. These studies assume implicitly myopic consumer behavior, or more bluntly, only the “experts” know this model but not the consumers. This paper extends the analysis to rational expectations (more precisely, perfect foresight due to a deterministic framework) and proves the (saddlepoint) stability of the equilibrium. Numerical examples highlight the differences of the two hypotheses, myopic versus rational consumer expectations. In particular, damped oscillations result for the empirical application (larger and more persistent for myopic consumers), which explains past volatility.
BOOK REVIEW
Authors: Narain Urvashi
Published: June 2017

Land Resource Economics and Sustainable Development: Economic Policies and the Common Good, G. Cornelis van Kooten, UBC Press, Vancouver, 1993, 450 pp.
THE RELATIVE EFFICIENCY OF DIFFERENT STANDARDS WHEN FIRMS VARY
Authors: Helfand Gloria E.
Published: June 2017

Pollution standards in practice take many forms, such as measuring pollution per unit of output rather than just restricting pollution. This paper uses simulations to provide some evidence on the effects of these two forms of standards when firms vary. For the cases studied, it shows that a pollution standard can lead to higher profits, but a pollution‐per‐output standard leads to higher output and lower price; the overall efficiency effects are therefore ambiguous.
OPTIMAL R&D FOR NONRENEWABLE RESOURCES: THE CASE OF COST REDUCING TECHNOLOGY
Authors: Norquist Suzanne M.
Published: June 2017

A model is developed to determine optimal R&D spending and completion time when R&D results in lower extraction costs of a nonrenewable resource deposit. Examples of R&D projects for which the model is designed are in‐situ leaching for mining and carbon dioxide injection in petroleum.

The model is a combined R&D/nonrenewable resource model (CM). Results from the CM are compared to simulations of an R&D model which ignores the nonrenewable resource. The comparison demonstrates the importance of including resource parameters in the R&D spending model.

The CM extends the literature by considering R&D spending and exhaustible natural resource production simultaneously. It demonstrates the importance of including the resource deposit when R&D affects the deposit. This is important because more accurate models of R&D will increase the profitability of the R&D projects.
OPTIMAL INSTAR PARASITIZATION IN A STAGE STRUCTURED HOST‐PARASITOID MODEL
Authors: Crowe Kathleen M. , Cushing J.M.
Published: June 2017

A stage structured host‐parasitoid model is derived and the equilibria studied. It is shown under what conditions the parasitoid controls an exponentially growing host in the sense that a coexistence equilibrium exists. Furthermore, for host populations whose inherent growth rate is not too large it is proved that in order to minimize the adult host equilibrium level it is necessary that the parasitoids attack only one of the larval stages. It is also proved in this case that the minimum adult host equilibrium level is attained when the parasitoids attack that larval stage which also maximizes the expected number of emerging adult parasitoid per larva at equilibrium. Numerical simulations tentatively indicate that the first conclusion remains in general valid for the model. However, numerical studies also show that it is not true in general that the optimal strategy will maximize the number of emerging adult parasitoid per larva at equilibrium.
MODELING COMMON PROPERTY OWNERSHIP AS A DYNAMIC CONTRACT
Authors: Caputo Michael R. , Lueck Dean
Published: June 2017

Common property ownership is modeled as a joint wealth maximizing egalitarian share contract. Two‐stage differential games are developed for various types of common property in order to examine the incentives inherent in common property regimes. Cases in which group members contract over just membership size and cases in which members contract over both group size and resource investment are considered. Envelope methods in optimal control theory are used to generate some comparative statics predictions about the value of the contracts which define property rights to a capital stock.
PARTIAL VERSUS GENERAL STORAGE POLICY: COMMODITIES AND RESOURCES
Authors: Just Richard E. , Lichtenberg Erik , Zilberman David
Published: June 2017

This paper examines joint storage considerations when both commodities and resources can be stored, e.g., grain and water for irrigation. Results suggest that when separate agencies control public resource and commodity storage, suboptimal storage rules occur unless (i) each agency is sensitive to the policies of the other, (ii) commodity inventories are adjusted in response to prices, and (iii) resource inventories are adjusted in response to both commodity demand and resource supply conditions. For example, the common case where water storage depends on weather and reservoir conditions alone is not sufficiently general. The results imply that water management agencies that tend to be dominated by engineers and hydrological considerations need to incorporate economic considerations into decision processes.
ENDANGERED SPECIES AND NATURAL RESOURCE EXPLOITATION: EXTINCTION VS. COEXISTENCE
Authors: Tsur Yacov , Zemel Amos
Published: June 2017

A model of renewable resource exploitation under event uncertainty is formulated. The model is applied to analyze the situation in which excessive water diversion for human needs can lead to the extinction of an animal population. Special attention is given to uncertainty regarding the conditions that lead to extinction. The manner in which the potential benefit foregone due to the species' extinction (the “extinction penalty”) induces more conservative exploitation policies is studied in detail. When the extinction penalty is ignored, the optimal policy is to drive the resource stock to a particular equilibrium level from any initial state. When the extinction penalty is accounted for and the conditions that lead to extinction are not fully understood (i.e., involve uncertainty), an interval of equilibrium states is identified, which depends on the penalty and on the immediate extinction risk.
A MODEL OF THE NORTH CAROLINA BAY SCALLOP FISHERY WITH ENDOGENOUS FISHING EFFORT AND ENTRY
Authors: Benford Frank A.
Published: June 2017

The principal purpose of this model is to aid in the evaluation and design of regulations that affect the fishery. It differs from most previous models with a similar purpose in three ways. (1) Daily fishing costs are assumed to vary among fishermen. (2) Daily fishing effort is determined endogenously rather than being treated as a control variable. (3) Entry into the fishery is determined endogenously up to a cap imposed by the regulatory agency. The model explains the adverse reaction to a proposed attempt to increase the value of the fishery by delaying the opening date. The model is used to predict the economic consequences of four feasible sets of regulations.
IMPUTING MISSING NATURAL RESOURCE INVENTORY DATA AND THE BOOTSTRAP
Authors: Gomez Irma A. , Burton Diana M. , Love H. Alan
Published: June 2017

Gathering information on natural resource inventories is expensive, but lack of data inhibits resource sector modeling and policy analysis. Most work has focused on drawing broader inventory estimates from small survey samples. Other studies have used simple forward forecasting equations to project missing values. This research develops a method to impute missing inventory and growth observations when annual survey observations are not available. A one‐way error component model is estimated and missing inventory values are imputed using an optimally weighted combination of forward and backward projections. This method ensures conformity of imputed observations with beginning and ending inventories. Confidence intervals for imputed inventory estimates are formed using the bootstrap method. Empirical results for estimated softwood and hardwood inventories in Louisiana are presented.
AN OPTIMIZATION APPROACH TO IDENTIFYING TIMBER SUPPLY FUNCTION COEFFICIENTS
Authors: Gong Peichen
Published: June 2017

This paper examines an optimization approach to identifying short‐run timber supply function coefficients when the form of the supply function is known. By definition, a short‐run timber supply function is a functional relationship between the optimal harvest level in each period (e.g., each year) and the actual forest‐market state in the same period. The short‐run timber supply function represents the optimal harvest decision policy, and therefore, the problem of optimal harvesting can be formulated as a problem of determining this function. When the form of the supply function is known, the problem becomes one of identifying the coefficients of the supply function. If the management objective is to maximize the expected present value of net revenues from timber harvesting over an infinite time horizon, and the timber price process is, in a sense, stationary, the supply function coefficients correspond to the optimal solution to an anticipative optimization problem. In this case, the supply function coefficients can be determined by maximizing the expected present value of the net revenues from timber harvesting, where periodic harvest levels are determined using the supply function. Numerical results show that the short‐run supply functions determined using this approach gives good approximations of the true supply function.
GAME‐THEORETIC INSIGHTS INTO THE INTERNATIONAL MANAGEMENT OF FISHERIES
Authors: McKelvey Robert
Published: June 2017

Ongoing efforts to negotiate agreements on management of transboundary marine fisheries tend to be arduous and frustrating, often collapsing into spectacular “fish wars” that leave fishing communities impoverished and fish stocks decimated. Game theory models can provide insights into why this is so, and suggest ways in which cooperative agreements might be crafted to overcome the difficulties. This article illustrates these themes through a model of a bi‐national “interception fishery.” The central focus of the analysis is on instabilities that result from stochastic variability and incomplete and asymmetric information.
DIFFUSION‐DRIVEN INSTABILITY IN THE GIERER‐MEINHARDT MODEL OF MORPHOGENESIS
Authors: Ruan Shigui
Published: June 2017

In this paper, we consider the Gierer‐Meinhardt model of morphogenesis. It is shown that the homogeneous equilibrium solution and the homogeneous periodic solution become diffusively unstable if the diffusion coefficients of the two substances are chosen suitably.
STABLE PERIODIC BEHAVIOR IN PIONEER‐CLIMAX COMPETING SPECIES MODELS WITH CONSTANT RATE FORCING
Authors: Sumner Suzanne
Published: June 2017

Two‐dimensional pioneer‐climax models of competing species differential equations are studied where the per capita growth rates are functions of weighted densities of the populations. The per capita growth rate of the pioneer species is monotonically decreasing whereas the per capita growth rate of the climax species is a one‐humped function of the total weighted density. Constant rate forcing is introduced into the model representing stocking or harvesting. General formulas are calculated for determining the stability of the periodic orbit arising from a Hopf bifurcation.
OPTIMIZING SPATIAL AND DYNAMIC POPULATION‐BASED CONTROL STRATEGIES FOR INVADING FOREST PESTS
Authors: Hof John
Published: June 2017

This paper explores spatial optimization approaches to managing invading exotic forest pests. The relevant land planning area is divided into cells, and pest population growth and dispersal are modeled with linear, continuous‐variable formulations. Management actions are limited to those that apply directly to pest extermination, as opposed to host‐oriented management actions. A stylized case example is used to demonstrate the potential application of the model formulation and to show that simple spatial strategies such as “barrier zone” approaches to slowing an organism's invasion may not always be optimal.
MODELING DYNAMICS OF FISHERY HARVEST REALLOCATIONS: AN ANALYSIS OF THE NORTH CAROLINA RED DRUM FISHERY
Authors: Schuhmann Peter W.
Published: June 2017

The interactive dynamics of red drum stock growth and two‐sector harvest are modeled as a system of differential equations. The dynamic effects of commercial harvest restrictions on stock growth and recreational catch and effort are simulated. The simulation shows that a reallocation of the North Carolina red drum stock from the commercial sector to the recreational sector will not only increase benefits to the recreational sector, but will also be stock enhancing. Stock growth in the years immediately following the reallocation is quite rapid, with complete transition to the final steady‐state taking between 23 and 46 years. Parameters important to the behavior of the system are identified through sensitivity analysis, and are used to establish critical areas for further research.