bluuebunny/crossref_metadata_2025 huggingface dataset:
Climate drives among‐year variation in natural selection on flowering time
Authors: Ehrlén Johan , Valdés Alicia
Published: January 2020

To predict long‐term responses to climate change, we need to understand how changes in temperature and precipitation elicit both immediate phenotypic responses and changes in natural selection. We used 22 years of data for the perennial herb Lathyrus vernus to examine how climate influences flowering phenology and phenotypic selection on phenology. Plants flowered earlier in springs with higher temperatures and higher precipitation. Early flowering was associated with a higher fitness in nearly all years, but selection for early flowering was significantly stronger in springs with higher temperatures and lower precipitation. Climate influenced selection through trait distributions, mean fitness and trait−fitness relationships, the latter accounting for most of the among‐year variation in selection. Our results show that climate both induces phenotypic responses and alters natural selection, and that the change in the optimal phenotype might be either weaker, as for spring temperature, or stronger, as for precipitation, than the optimal response.
Risk factors associated with progressive lacunar strokes and benefit from dual antiplatelet therapy
Authors: Berberich A. , Schneider C. , Herweh C. , Hielscher T. , Reiff T. , Bendszus M. , Gumbinger C. , Ringleb P.
Published: January 2020

Background and purpose

Early neurological deterioration (END) occurs in 20%–30% of patients with lacunar stroke and challenges their clinical management. This retrospective cohort study analyzed clinical and neuroimaging risk factors predicting the occurrence of END, the functional outcome after END and potential benefit from dual antiplatelet therapy (DAPT) in patients with lacunar strokes.

Methods

Factors associated with END and benefit from DAPT were retrospectively analyzed in 308 patients with lacunar stroke symptoms and detected lacunar infarction by magnetic resonance imaging. END was defined by deterioration of ≥3 total National Institutes of Health Stroke Scale (NIHSS) points, ≥2 NIHSS points for limb paresis or documented deterioration within 5 days after admission. Patients were treated with DAPT according to in‐house standards. The primary efficacy end‐point for functional outcome was fulfilled if NIHSS at discharge improved after END at least to the score at admission.

Results

Male gender [odds ratio (OR) 2.08; 95% confidence interval (CI) 1.09–4.00], higher age (OR = 1.65 per 10 years; 95% CI 1.18–2.31), motor paresis (OR = 18.89, 95% CI 4.66–76.57) and infarction of the internal capsule or basal ganglia (OR = 3.58, 95% CI 1.26–10.14) were associated with an increased risk for END. A larger diameter of infarction (OR = 0.85, 95% CI 0.76–0.95), more microangiopathic lesions (OR = 0.75, 95% CI 0.57–0.99) and pontine localization (OR = 0.29, 95% CI 0.12–0.65) were factors associated with unfavorable functional outcome after END occurred. Localization in the internal capsule or basal ganglia was identified as a significant predictive factor for a benefit from DAPT after END.

Conclusions

Identified clinical and neuroimaging factors predicting END occurrence, functional outcome after END and potential benefit from DAPT might improve the clinical management of patients with lacunar strokes.
The risk of epilepsy in children with celiac disease: a population‐based cohort study
Authors: Canova C. , Ludvigsson J.F. , Barbiellini Amidei C. , Zanier L. , Zingone F.
Published: January 2020

Backgroundand purpose

The purpose was to estimate the risk of epilepsy in a cohort of young individuals with celiac disease (CD) compared to that of matched references.

Methods

The cohort consisted of 213 635 individuals born during 1989–2011 and residing in Friuli‐Venezia Giulia (Italy). 1215 individuals affected by CD and 6075 reference individuals matched by sex and age were identified. Epilepsy was defined by means of hospital diagnosis or drug prescriptions. Conditional logistic regression was used to estimate the odds ratios (ORs) of having epilepsy amongst individuals with CD, before CD diagnosis and in the entire period, compared with those of their matched references. Cox regression was used to calculate the hazard ratios for epilepsy diagnosed after CD diagnosis. Different definitions of epilepsy were used for sensitivity analyses.

Results

Thirty‐one (2.6%) individuals with CD and 78 (1.3%) reference individuals had epilepsy [adjusted OR 2.03; 95% confidence interval (CI) 1.33–3.10]. The risk of epilepsy was increased prior to CD (adjusted OR 2.29; 95% CI 1.33–3.94), with similar estimates after CD diagnosis (adjusted hazard ratio 1.96; 95% CI 0.95–4.02). The increased risk of epilepsy was not explained by a peak in epilepsy diagnosis just around CD diagnosis. Sex stratification found a significantly higher risk of epilepsy amongst female individuals with CD. Sensitivity analyses confirmed the positive association between CD and epilepsy.

Conclusion

Children and youths with CD were at increased risk of epilepsy. Patients with epilepsy without a clear etiology should be screened for CD since an early diagnosis and treatment might improve the response to antiepileptic therapies.
Periodontitis phenotypes and clinical response patterns to non‐surgical periodontal therapy: reflections on the new periodontitis classification
Authors: Nascimento Gustavo G. , Dahlén Gunnar , López Rodrigo , Baelum Vibeke
Published: January 2020

We aimed to identify response patterns to non‐surgical periodontal therapy and to investigate whether the new classification system for periodontitis reflects response to treatment after 1 yr. At baseline, data on sociodemographic status, smoking, and diabetes were obtained from participants with periodontal disease. Clinical periodontal data and subgingival plaque were also collected. Participants underwent non‐surgical periodontal therapy, and after 3 and 12 months, clinical data were reassessed. Factor analyses, group‐based‐trajectory modeling, and mixed‐effects regression models were used for data analysis. Factor analysis of the baseline periodontal parameters revealed two different periodontitis dimensions: ‘moderate’ and ‘severe’. Two response patterns for each of these periodontitis dimensions were identified. Periodontal therapy had a beneficial effect on both ‘moderate’ and ‘severe’ periodontitis; however, individuals with higher levels of disease at baseline experienced greater treatment effect. Regarding the new classification system, while the staging component distinguished different levels of ‘moderate’ and ‘severe’ periodontitis before and after treatment, the grading component did not. This study shows the beneficial effect of non‐surgical periodontal therapy on both ‘moderate’ and ‘severe’ periodontitis. However, the benefit was limited among individuals with low levels of disease. The new classification system did not adequately reflect the periodontal response to therapy in this patient group.
Protease‐activated prodrugs: strategies, challenges, and future directions
Authors: Poreba Marcin
Published: January 2020

Proteases play critical roles in virtually all biological processes, including proliferation, cell death and survival, protein turnover, and migration. However, when dysregulated, these enzymes contribute to the progression of multiple diseases, with cancer, neurodegenerative disorders, inflammation, and blood disorders being the most prominent examples. For a long time, disease‐associated proteases have been used for the activation of various prodrugs due to their well‐characterized catalytic activity and ability to selectively cleave only those substrates that strictly correspond with their active site architecture. To date, versatile peptide sequences that are cleaved by proteases in a site‐specific manner have been utilized as bioactive linkers for the targeted delivery of multiple types of cargo, including fluorescent dyes, photosensitizers, cytotoxic drugs, antibiotics, and pro‐antibodies. This platform is highly adaptive, as multiple protease‐labile conjugates have already been developed, some of which are currently in clinical use for cancer treatment. In this review, recent advancements in the development of novel protease‐cleavable linkers for selective drug delivery are described. Moreover, the current limitations regarding the selectivity of linkers are discussed, and the future perspectives that rely on the application of unnatural amino acids for the development of highly selective peptide linkers are also presented.
Protein scaffold involving MSMEG_1285 maintains cell wall organization and mediates penicillin sensitivity in mycobacteria
Authors: Veyron‐Churlet Romain , Saliou Jean‐Michel , Locht Camille
Published: January 2020

Protein–protein interactions are key in mycobacterial physiology, notably during the biosynthesis of the very peculiar mycobacterial cell wall. In this paper, we demonstrate that MSMEG_1285 interacts with PonA1, a bifunctional penicillin‐binding protein involved in peptidoglycan biosynthesis. Deletion of MSMEG_1285 enhances Mycobacterium smegmatis resistance to penicillin antibiotics, a phenotype that is exacerbated by the additional deletion of hbhA. This also led to a substantial decrease in the amounts of porins in the cell wall, which are necessary for the import of small and hydrophilic β‐lactams. Deletion of both MSMEG_1285 and hbhA provoked an over‐representation of several enzymes involved in peptidoglycan degradation. Thus, we propose that MSMEG_1285 is part of a protein scaffold, which also involves PonA1 and HbhA, and that it is responsible for the tight regulation of peptidoglycan hydrolysis. This study provides a better understanding of the mycobacterial physiology, which is an essential step for strengthening the action of drugs that specifically target peptidoglycan biosynthesis.
S‐N curve for riveted details in corrosive environment and its application to a bridge
Authors: Adasooriya N.D. , Hemmingsen T. , Pavlou D.
Published: January 2020

A formula for stress‐life curve is proposed to predict the fatigue life of riveted bridges located in corrosive environments. The corrosive environment‐dependent parameters of the S‐N curve are determined based on the corrosion fatigue testing results of different types of steel specimens in air, fresh water, and seawater. Eurocode detail category 71 and UK WI‐rivet detail category represent the fatigue strength of riveted members. The proposed S‐N curve formula is compared with full‐scale fatigue test results of riveted joints, plate girders, and truss girders, which were tested in a corrosive environment. Thus, the validity of the formula is confirmed. The formula does not require any material parameter other than the code‐given fatigue curve of riveted details. The fatigue life of a riveted railway bridge is estimated by using the proposed formula, and the results are compared with conventional approaches. The applicability and significance of the proposed curve are confirmed.
Hotspots of biotic compositional change in lakes along vast latitudinal transects in northern Canada
Authors: Saulnier‐Talbot Émilie , Antoniades Dermot , Pienitz Reinhard
Published: January 2020

Ecotones mark zones of rapid change in ecological structure at various spatial scales. They are believed to be particularly susceptible to shifts caused by environmental transformation, making them key regions for studying the effects of global change. Here, we explored the variation in assemblage structure of aquatic primary producer and consumer communities across latitudinal transects in northeastern North America (Québec‐Labrador) to identify spatial patterns in biodiversity that indicated the location of transition zones across the landscape. We analyzed species richness and the cumulative rate of compositional change (expressed as beta‐diversity) of diatoms and chironomids to detect any abrupt shifts in the rate of spatial taxonomic turnover. We used principal coordinates analysis to estimate community turnover with latitude, then applied piecewise linear regression to assess the position of ecotones. Statistically significant changes in assemblage composition occurred at 52 and 55°N, corresponding to the transition between closed‐ and open‐crown forest, and to the southern onset of the forest tundra (i.e., the forest limit), respectively. The spatial distribution of ecotones was most strongly related to air temperature for chironomids and to vegetation‐ and soil‐related chemical attributes of lake water for diatoms, including dissolved organic carbon content and water color. Lakes at mid‐ to high‐latitudes currently face pressures from rapidly rising temperatures, accompanied by large increases in organic carbon inputs from their catchments, often leading to browning and its associated effects. The biota at the base of food webs in lakes located in transition zones are disproportionately affected by the cascading effects of these multi‐factorial changes, concurrent with pronounced terrestrial greening observed in these regions. Similar patterns of biotic shifts have been observed along alpine aquatic transects, indicating the potential for widespread restructuring of cold, high‐altitude and high‐latitude freshwater communities due to global change.
Chronic stressors, stress coping and depressive tendencies among older adults
Authors: Murayama Yoh , Yamazaki Sachiko , Yamaguchi Jun , Hasebe Masami , Fujiwara Yoshinori
Published: January 2020

Aims

This study aimed to clarify the association between chronic stressors, stress coping and depressive tendencies among older adults.

Methods

We carried out a survey with 500 participants aged in their 70s, who were randomly selected from the basic resident register. Of these, 304 residents responded to the survey (60.8%).

Results

Findings from a factor analysis and cluster analysis revealed five groups of chronic stressors: physical, economic and interpersonal stressor; physical and economic stressor; interpersonal stressor; physical stressor; and low stressor. The factor analysis revealed four factors of coping: cognitive coping, support‐seeking, positive problem solving and escape–avoidance. Furthermore, a multiple logistic regression analysis showed that both physical, economic and interpersonal stressor, and physical and economic stressor had negative associations with depressive tendencies. With respect to stress coping, positive problem solving had a positive association with depressive tendencies, whereas escape–avoidance had a negative association with depressive tendencies.

Conclusions

For older individuals, the more complex the overlapping chronic stressors that are experienced, the higher the depressive tendencies. Furthermore, although older individuals selectively use various coping strategies, they do not alleviate the stress responses induced by chronic stressors. Geriatr Gerontol Int 2020; 20: 297–303.
Application of bibliometrics in medicine: a historical bibliometrics analysis
Authors: Kokol Peter , Blažun Vošner Helena , Završnik Jernej
Published: January 2020

Background

The application of bibliometrics in medicine enables one to analyse vast amounts of publications and their production patterns on macroscopic and microscopic levels.

Objectives

The aim of the study was to analyse the historical perspective of research literature production regarding application of bibliometrics in medicine.

Methods

Publications related to application of bibliometrics in medicine from 1970 to 2018 were harvested from the Scopus bibliographic database. Reference Publication Year Spectroscopy was triangulated with the VOSViewer to identify historical roots and evolution of topics and clinical areas.

Results

The search resulted in 6557 publications. The literature production trend was positive. Historical roots analysis identified 33 historical roots and 16 clinical areas where bibliometrics was applied.

Discussion

The increase in productivity in application of bibliometrics in medicine might be attributed to increased use of quantitative metrics in research evaluation, publish or perish phenomenon and the increased use of evidence‐based medicine.

Conclusion

The trend of the literature production was positive. Medicine was in the forefront of knowledge development in bibliometrics. reference publication year spectroscopy proved to be an accurate method which was able to identify most of the historical roots.
Horseshoe Regularisation for Machine Learning in Complex and Deep Models1
Authors: Bhadra Anindya , Datta Jyotishka , Li Yunfan , Polson Nicholas
Published: January 2020

Since the advent of the horseshoe priors for regularisation, global–local shrinkage methods have proved to be a fertile ground for the development of Bayesian methodology in machine learning, specifically for high‐dimensional regression and classification problems. They have achieved remarkable success in computation and enjoy strong theoretical support. Most of the existing literature has focused on the linear Gaussian case; for which systematic surveys are available. The purpose of the current article is to demonstrate that the horseshoe regularisation is useful far more broadly, by reviewing both methodological and computational developments in complex models that are more relevant to machine learning applications. Specifically, we focus on methodological challenges in horseshoe regularisation in non‐linear and non‐Gaussian models, multivariate models and deep neural networks. We also outline the recent computational developments in horseshoe shrinkage for complex models along with a list of available software implementations that allows one to venture out beyond the comfort zone of the canonical linear regression problems.
Institutional Reform of Marketing and Related Services to Agriculture, With Particular Reference to Africa
Authors: Abbott John C.
Published: January 2020

Over the decades to 1980 agricultural marketing and input supply systems came increasingly under official monopolies. Dissatisfaction with the incentives offerred to producers and with the costs to governments has sparked interest in reform. Practicable ways of introducing more competition and mobilizing potential individual initiatives are presented. Obstacles to progress in this direction include political commitments of governments, ethnic concerns and patronage interests. External aid can help ease these constraints.
Structural Change and its Impact on Traditional Agricultural Sectors of Rapidly Developing Countries: The Case of Natural Rubber
Authors: Barlow Colin , Jayasuriya S.K.
Published: January 2020

Rapid structural change is now a major feature of several Southeast Asian economies. It generally involves greatly expanded exports of certain commodities and manufactures accompanied by a large growth in services, and poses serious difficulties for traditional labour‐intensive sectors. One important sector affected in this way is that producing natural rubber in Malaysia, Indonesia and Thailand.

The difficulties mentioned occur through both “resource pull” effects ‐ which are especially important in raising real wages, and “spending” effects ‐ which tend to lead to an appreciation of the real exchange rate. These effects, and the problems arising from them, are examined and compared for each of the rubber sectors above.

While changes of this nature call for diminution in the size of traditional sectors, there is also a need to improve economic efficiency, notably by adopting new technology more appropriate to the emerging resource price configuration, and by moving to an agriculture where off‐farm employment and other linkages are increasingly significant. Such adjustment may be both helped and constrained by institutional factors and official policies, which accordingly require careful review.

These crucial policy issues, and the degree to which necessary adjustments have been made, are investigated for the rather different contexts in each of the three natural rubber‐producing countries. The analysis is thought to have wider relevance for other developing countries with traditional agricultural sectors.
Macroeconomic Policy Impacts on United States Agriculture: A Simulation Analysis
Authors: Barclay Tom , Tweeten Luther
Published: January 2020

United States monetary and fiscal policies influence the domestic agricultural economy directly and, through international linkages, indirectly. This study estimates the magnitude and statistical influence of coefficients relating U.S. macroeconomic policy to the U.S. agricultural economy through domestic and foreign markets. Specific objectives are to specify and estimate a general equilibrium quarterly econometric model of the U.S. macroeconomy and simulate the impact of federal deficit spending on real interest rates, real exchange rates, and net exports of agricultural products. Three hypotheses were tested. The first hypothesis that an increase in federal deficit spending increases the real interest rate could not be rejected; a $100 billion reduction in the U.S. deficit was estimated to reduce real interest rates by two percentage points or more. The second hypothesis that an increase in real interest rate increases the real value of the U.S. dollar in foreign exchange markets had strong support and could not be rejected. A third hypothesis that a rise in the real value of the dollar reduces net exports of U.S. farm products also could not be rejected. Results indicate that the U.S. agriculture would benefit from the lower exchange value associated with an ‘optimal’ macroeconomic policy. That policy initially made the overall U.S. economy perform less satisfactorily but that performance improves over time.
Labour on the Family Farm: a Theory under Uncertainty
Authors: Dawson P.J.
Published: January 2020

This paper develops a theory of the family farm in conditions of uncertainty where attention is focussed on the labour‐input decisions. Specifically, the farm family is faced with two labour decisions, namely with respect to hired labour and to family labour. The framework for analysis is expected utility maximisation. The analysis has implications for agricultural policy since policy pronouncements of economists are typically based on models which assume perfect certainty. These pronouncements do not survive the incorporation of uncertainty.
On the Reform of Rural Supply and Marketing Cooperatives in China
Authors: Wan Guang H. , Zhou Zhang Y. , Dillon John L.
Published: January 2020

As a bridge between city and countryside, industry and agriculture, producer and consumer, Rural Supply and Marketing Cooperatives (RSMCs) play a key role in distributing commodities and purchasing rural products for some 800 million people in China. While overall national economic reform started in 1978, the reform of RSMCs began 4 years later in 1982 with greater emphasis on recovery rather than reform. This paper reviews the development of RSMCs, describes their operation and appraises the reform underway since 1982. It concludes with some policy suggestions relative to further reform of the RSMC system.
Examining the Leontief Paradox in U.S. Agricultural Trade
Authors: Lee Chinkook , Wills Darryl , Schluter Gerald
Published: January 2020

Factor intensity of United States agricultural trade is examined in the context of Leontief's classic paradox using Leontief's method as well as methods developed recently by Leamer and others. Findings indicate that factor endowments are important determinants of U.S. agriculture's comparative advantage in trade as suggested by the Heckscher‐Ohlin theory.
Crop Selection and Implications for Profits and Wind Erosion in a Semi‐Arid Environment
Authors: Lee John G. , Ellis John R. , Lacewell Ronald D.
Published: January 2020

A daily crop growth simulation model was applied to four dryland cropping systems to estimate the profit distributions for each of four price series under stochastic weather conditions on the Southern High Plains of Texas. Stochastic dominance with respect to a function was utilized to rank each crop rotation for different risk‐averse intervals. Solutions from the model indicate that long‐term average annual soil loss due to wind erosion was a function of the producer's risk aversion, price expectation, and discount rate which affect the optimal crop rotation selection.
Welfare Implications of a Preferential Tariff Reduction for Agricultural Exports from Less Developed Countries vs. a Generalized Tariff Reduction
Authors: Anania Giovanni
Published: January 2020

The paper presents the results of a theoretical study focusing on a comparative evaluation of the welfare effects of a preferential tariff reduction for agricultural exports from less developed countries versus a generalized tariff reduction. The results are derived using a diagrammatic approach. The analysis is developed within a partial equilibrium framework with one commodity, three large countries (importing developed country, exporting developed country, developing country), fixed exchange rates and zero transportation costs. The theoretical model makes provisions for a country to switch from being an exporter to being an importer, or vice versa, as the equilibrium price changes. Three alternative policy scenarios are analyzed: the imposition of a non‐discriminatory tariff, a preferential tariff reduction, and a generalized tariff reduction. Two alternative definitions of the welfare functions are used. One is based on consumers' and producers' surplus, the other adds domestic income and changes in foreign exchange earnings/expenditure. Some methodological implications of the specific model used are discussed, along with the impact, in terms of welfare, of the policy scenarios considered.
Expected Economic Effects of BST in The Netherlands
Authors: Giesen G.W.J. , Oskam A.J. , Berentsen P.B.M.
Published: January 2020

The calculated profitability of using Bovine Somatotropin (BST) on typical dairy farms in The Netherlands ranges from Dfl.160 to 300 per cow per year, assuming 1985 prices and circumstances, and ignoring the costs of BST. A 20% increase in milk production and no change of the feed/milk relation were used for the calculations. BST is more profitable on intensive farms or on farms with more opportunities for alternative uses of land, buildings and labour. The quota system, however, leads to a considerable reduction of profitability.

At a national level, and with an unchanged milk price, a 28% adoption rate of BST would increase national income about Dfl.120 million. However, the cost of BST or any decrease in milk price could reduce this amount, even to below zero. It is apparent that some dairy farmers who apply BST will earn more income whereas others will lose income.
Agricultural Research Problems in Small Developing Countries: Case Studies from the South Pacific Island Nations
Authors: Hardaker J. Brian , Fleming Euan M.
Published: January 2020

While research‐based technological improvements are an important part of a successful agricultural development strategy, the small South Pacific Island Nations face special difficulties in attaining such innovations because of their particular agricultural production and marketing circumstances and because of diseconomies of small size in research. There is a need to sharpen the focus of national agricultural research efforts on adaptive work, implying both increased international and regional collaboration and the reorientation of national programs to be more receptive to outside ideas and information. It is particularly important to seek a parsimonious research paradigm, involving a broadening of the range of people who contribute to the research process.
Agricultural Technology and Farm–Nonfarm Growth Linkages
Authors: Haggblade Steven , Hazell Peter
Published: January 2020

Agricultural growth stimulates rural nonfarm activity by boosting demand for production inputs and consumer goods. But different kinds of agricultural technology promote different patterns of nonfarm linkages. To explore how key features of agricultural technology affect growth in the rural nonfarm economy, this paper reviews an array of cross‐section and time‐series evidence bearing on the dynamics of the rural nonfarm economy. Then, using consumption and production parameters associated with different agricultural technologies, it introduces a simple model which isolates the effects of different technologies on nonfarm growth linkages.
Risk‐Efficient Irrigation Strategies for Wheat
Authors: Pandey Sushil
Published: January 2020

Agricultural production is risky. When farmers are risk‐averse, they are likely to put a premium on production methods that reduce perceived risks. Irrigation is generally believed to be a risk‐reducing input. By using the concept of stochastic dominance, risk‐efficient irrigation policies for wheat grown in central India are identified and quantitative estimates of benefits due to risk reduction are obtained. Such benefits were found to be of a large order of magnitude. The more common methods such as mean variance analysis tended to over‐estimate the benefits.
Analysis of Uncertainty as Opposed to Risk: An Experimental Approach
Authors: Anand Paul
Published: January 2020

The paper illustrates the scope for enhancing the conceptual apparatus used by agricultural economists to analyse decision‐making under conditions of uncertainty. Selected empirical results from experiments on student subjects from three universities are reported. Three issues are considered. First, the reasons for choice and the understanding of a choice problem are examined. Second, attitudes towards different levels of uncertainty are measured. Third, the possibility that apparently non‐normative psychological factors influence choice is explored. The paper serves to illustrate and support a number of methodological points. The major points are that a risk‐uncertainty distinction is useful (contrary to the aging conventional wisdom of economic theory), that laboratory experiments can potentially provide data of use to agricultural economists, and that predictive models of choice under uncertainty may be more accurate if they take account of psychological variables which influence the decision‐making processes of human subjects.
Welfare Effects of Selected Food‐grain Policies in India
Authors: Chetty V.K. , Srinivasan P.V.
Published: January 2020

Government's policy interventions in the market for food‐grains affect supply as well as demand. In this paper, the welfare effects of certain food‐grain policies are analysed while taking into account the interdependence of the various sectors in the economy. Adequate structure is built into the model in order to study the effects of a dual price structure on farmers' supply response, and also the effects of public distribution schemes on the aggregate demand for food‐grains. Policy implications are derived by computing the market clearing prices and their movement under alternative assumptions regarding the nature of the market.
Transfer of sustainable technology in dryland agriculture: Lessons from the Sahel in the 1980's
Authors: Deuson Robert R. , Day John C.
Published: January 2020

Dryland agriculture in the Sahel must become more productive if human conditions in the region are to improve. Constraints impeding increased productivity are examined. The harsh natural environment of the Sahel means that technologies, institutions and economic policies must be tailored to meet the special challenges of that environment.
Modern rice technology and regional wage differentials in the Philippines
Authors: Otsuka Keijiro , Cordova Violeta G. , David Cristina C.
Published: January 2020

Fear has been widely expressed that the modern rice varieties have created large disparities in regional income distribution, as the productivity gap between favorable and unfavorable rice‐production environments widened due to differential technology adoption throughout South and Southeast Asia over the last two decades.

Technology affects the income of farm population directly through its effects on productivity and factor use, and indirectly through its effect on factor prices. In particular, the ultimate distributional impact of modern varieties will critically depend on the interregional labor‐market adjustments through migration in response to regional wage differentials created by the differential technology adoption, since labor is the main resource of the majority of the rural population.

We studied favorable and unfavorable rice‐growing villages in the Philippines, and found that adoption of modern varieties during the 1970s was positively related to population growth rate. Contrary to popular belief, no association was observed between wage rates and adoption of modern varieties as of 1986. These findings support the hypothesis that the differential adoption of modern rice varieties induced interregional labor migration toward equalization of wage income across different production environments.
The Calculation of returns to research in distorted markets: Comment
Authors: Voon Jan P. , Edwards Geoff W.
Published: January 2020

In a recent article, Oehmke reported that a high internal rate of return for investment in research when the interaction between research and price policy costs was disregarded could become very low or even negative when the effects of research on the costs of price policy were considered. In this paper, the social returns from research in the presence of the price policies considered by Oehmke are reexamined using a simple geometric approach. The analysis suggests that an output subsidy in a small importing economy, an output subsidy in a closed economy, and a target price in a large exporting economy will on Oehmke's assumptions ‐ cause only small reductions in the internal rate of return from investment in research. This implies that the apparent underinvestment by governments in agricultural research cannot be explained away by a large upward bias, known to governments, in measured rates of return due to failure to account for interactions between research and the costs of price policy measures.
Price and quantity adjustment in a dual character market The case of the Greek poultry sector
Authors: Alogoskoufis George , Baltas Nicholas
Published: January 2020

In this paper we set up, estimate and test a short‐run model for the poultry sector in Greece. The model allows for the simultaneous existence of a monopolistically competitive and a competitive segment, and determines producer and consumer prices, and the quantity consumed. We provide evidence on steady‐state parameters such as demand and supply elasticities, as well as on speeds of adjustment of prices and quantities. The evidence suggests that adjustment is very rapid, although quantities appear to be adjusting more quickly than prices. The model is used to examine the dynamics of adjustment to demand and supply‐side disturbances.
Rural banking in Nigeria: Empirical evidence of indicative policy variables from Anambra State
Authors: Okorie Aja
Published: January 2020

Ten years after the establishment of the Rural Banking Scheme (RBS) in Nigeria, there are clear indications that the problems and issues which led to the scheme are still prevalent. These include a low level of rural savings mobilization, inadequate use of banking services, and lack of credit for rural people.

The central assumptions of the scheme were that increasing the physical proximity of banks to rural people enhances rural savings mobilization and, in turn, increases the flow of funds to the rural sector. Consequently, Nigeria established a quasi‐commercial bank type of rural banking system, by means of legislation requiring commercial banks to open branches in rural areas. This study questions the validity of the underlying assumptions, and sets out to investigate the appropriate mix of policy variables necessary for establishing an effective rural banking system in Nigeria and other developing countries.

Rural residents were surveyed to find out which variables are important in determining rural bank use. Discriminant analysis showed that four variables were significant in discriminating between rural bank users and non‐users. These variables were household income, years of formal education, gender of respondent, and the awareness of the existence of the rural bank branch. The proximity of the bank to the respondent's residence was not a significant determining variable.

These findings have important implications for rural bank designers and implementors in Nigeria and other developing countries. They suggest that the current emphasis on the physical distance, as a critical factor in rural bank development, should be replaced by a broader and a more comprehensive strategy which would incorporate and utilize an appropriate mix of policy variables to enhance the effectiveness of the rural banks in Nigeria.
Principles of stochastic dynamic optimization in resource management: the continuous‐time case
Authors: Larson Bruce A.
Published: January 2020

A wide range of problems in economics, agriculture, and natural resource management have been analyzed using continuous‐time optimal control models, where the state variables change over time in a stochastic manner. Using a firm‐level investment model and a model of environmental degradation, this paper provides a concise introduction to continuous‐time stochastic control techniques. The process used to derive the differential of a stochastic process is stressed and, in turn, is used to explain Ito's lemma, Bellman's equation, the Hamilton‐Jacobi equation, the maximum principle, and the expected dynamics of choice variables. A basic extension of the dynamic duality literature is also provided, where the Hamilton‐Jacobi equation is used to derive a stochastic and dynamic analogue of Hotelling's lemma.
Effect of modern rice varieties and irrigation on household income distribution in Nepalese villages
Authors: Thapa Ganesh , Otsuka Keijiro , Barker Randolph
Published: January 2020

Since high‐yielding modern rice varieties (MVs) are adopted only in favorable production environments, significant regional productivity differentials have emerged in Nepal. This study explores the distributional consequences of such differential MV adoption based on an intensive survey of favorable and unfavorable villages. We found that MV adoption increased returns to land but decreased family labor earnings from rice production, as it facilitated the substitution of hired for family labor. As a result, the differential MV adoption did not significantly worsen the household income distribution according to the results of the counterfactual Gini decomposition analysis.
Cost structure and technical change in rural banking
Authors: Obben James
Published: January 2020

Using the multi‐product translog cost function, this paper examines the cost structure and technical change occurring within the novel Ghanaian rural banks. The results of the seemingly unrelated error components model indicate substantial unexploited economies of scale in individual products as well as in overall intermediation. There is presence of pairwise complementarity between loans and government securities and between deposits and government securities, but absence of pairwise complementarity between loans and deposits. Overall, capital‐using and labour‐saving technical change has occurred but efficiency loss in deposit mobilization outweighs the efficiency gains in government securities and lending activities; operation of agencies reinforces the overall efficiency loss. The rural banks must not be hindered from expanding, but in any growth strategy deposit mobilization should take a central position and the cost of operating agencies watched closely.
International trade and agricultural development in developing countries: Significance of the Uruguay Round of GATT negotiations
Authors: Koester Ulrich
Published: January 2020

Liberalization of world trade in agricultural products ranks high on the agenda of the Uruguay Round. After a period of more than six years, however, the negotiations have not been concluded. Nevertheless, an outcome seems to be in sight. The agreement will most likely not result in a move to freer trade. It seems that domestic policies will become even more regulative than in the past in an attempt to cut exportable surpluses and to ease trade tensions among the main exporting nations. This paper explores possible impacts of the GATT Round on agricultural development in developing countries. Agricultural development is more than only growth in agricultural production or productivity. However, it is argued in the paper that other variables which also indicate agricultural development are often closely correlated with growth in production and productivity. Trade in agricultural products is not always an engine for agricultural development. If internal divergences are not accounted for by appropriate domestic policies, trade may be even harmful to agricultural development. Hence, empirical research based on cross‐country analysis does not provide a clear answer about the role of trade for development.

Past policies in industrialized countries have most likely had a negative effect on developing countries as a group; however, the effects differ widely across countries. Liberalization policies in industrialized countries would not just reverse these negative effects for developing countries. Price reduction in industrialized countries may not result in the often‐cited production decline in the short term. Present X‐inefficiency in agriculture will be reduced by liberalization, leading to an outward shift of the supply curve. Hence, liberalization may not lead to higher world market prices for temperate‐zone products in the short and medium term. Apart from this, empirical models differ widely in the price effects they predict.

The expected outcome of the Uruguay Round – increased regulation of domestic policies – is likely both more negative for developing countries than past protectionist policies and worse than an overall liberalization. World market prices will increase, uncertainty and instability can be expected to grow, and food aid may become less available. There will be a need to react to these challenges with measures on the international and national level. Initiatives to deal with food crises in developing countries and to stimulate liberalization in developing countries should be considered. Finally, developing countries should be made aware that their own domestic policies have a much greater economic impact than policies in other countries, even if the latter are as protectionist as current agricultural policies in the industrialized world.
Mix and sequencing of economywide and agricultural reforms: Chile and New Zealand
Authors: Valdés Alberto
Published: January 2020

Once committed to economywide and sectoral reforms – stabilization, structural adjustment, and trade liberalization – and companion reforms of institutions, how does government best proceed? With what reforms in response to initial conditions, and in what mix, sequence, strength, and speed? This study examines what factors were most critical to success during transition in two early reformers. The economies of Chile and New Zealand have undergone seismic reforms, starting in the mid‐1970s and 1980s, respectively. Comparative analysis of their reforms look at the prior conditions that induced drastic action and the policy choices made in each country. Though similar in many respects, differences in initial economic conditions and implementation led to dissimilar, even contrary results. For Chile, the outcome was a vigorous, recharged economy and agricultural sector; for New Zealand, the economy and the sector are lagging still. How policy choice and implementation, as well as simultaneity of reforms, affected the outcomes is the major thrust of the study. The preeminence of trade and macroeconomic policies over sectoral interventions, and in particular the strategic nature of the real exchange rate in allowing agriculture to compete domestically and internationally highlight the discussion.
Trade and agricultural development in the 1980s and the challenges for the 1990s: Latin America
Authors: Schuh G. Edward , Junguito Roberto
Published: January 2020

Trends in agricultural trade for South and Central America are documented and the reform process is discussed. Performance of the agricultural sector of the region is evaluated. Challenges for policy makers are reviewed, ranging from macroeconomic policy to science and technology.
Challenges of trade and agricultural development for East/Central Europe and states of the former USSR
Authors: Brooks Karen M.
Published: January 2020

The agricultural transition in Central and Eastern Europe and the former USSR reflects a fundamental change in development strategy, and will have a profound impact on agricultural trade. The greatest impact will be indirect, through agriculture's contribution to general economic reform and acceleration of regional and global growth. The direct impact on trade in food and fiber will in aggregate consist of a fall in net imports. Most of the decline in net imports will derive from reduction in demand and improved utilization. Potential for productivity increase is substantial, but not all of the increased productivity will be reflected in the traditional supply response of increased production. Instead marginal resources will shift out of farming, and producers will restructure and adopt new technologies in pursuit of lower costs. Shifts in the commodity composition of trade will occur, and the changes in grain and livestock markets will be greatest. If the reform is successful, the former Soviet Union could become a modest net grain exporter instead of a large importer. Wheat would be the leading export grain, and levels of wheat exports and corn imports could become quite sensitive to relative prices on world markets.
Production economics: Worthwhile investment?
Authors: Shumway C. Richard
Published: January 2020

Agricultural production economics research is examined within a broad framework of scientific development and utilization. Recent findings in selected areas of the subdiscipline are examined and opportunities for further fruitful inquiry are identified. A few 'stylized facts' emerge from recent work and suggest the need for much careful hypothesis testing, model exploration, and empirical sensitivity analysis in the future.
Agriculture‐led growth: foodgrains versus export crops in Madagascar
Authors: Dorosh Paul , Haggblade Steven
Published: January 2020

This article compares the growth‐generating power of alternative agricultural development strategies in Madagascar. Projections from a semi‐input–output model and a recently developed social accounting matrix suggest that both paddy and export crops stimulate strong linkages with other sectors of the Malagasy economy. But since paddy output can be increased at lower cost, investment in rehabilitating small irrigated rice perimeters generates 40% to 100% more gdp than a comparable investment in coffee production. Paddy also generates greater employment and a more equitable income distribution.
Analysis of the technical efficiency of state rubber farms in Vietnam
Authors: Son Tran Vo Hung , Coelli Tim , Fleming Euan
Published: January 2020

This study entails an analysis of the technical efficiency of natural rubber production by state farms in Vietnam. A time‐varying stochastic frontier production function model for unbalanced data is estimated for 33 farms. Individual farm technical efficiencies are reported and discussed. One of the main results concerns the bimodal distribution of technical efficiency indices. A few farms operate near the production frontier while the bulk operate well away from the frontier. Some implications are drawn from the results as a guide to future policy research work in the rubber industry in light of recent moves by the Vietnamese government towards economic reform.