bluuebunny/crossref_metadata_2025 huggingface dataset:
Quasi Maximum Likelihood Estimation of Multivariate Probit Models: Farm Couples' Labor Participation
Authors: Kimhi Ayal
Published: July 2006

Joint estimation of farmers' farm and off‐farm work participation requires a multivariate probit model, in which the number of equations is twice the number of household members. Where there are more than two such equations, I suggest a quasi maximum likelihood method which requires only two levels of numerical integration. The method maximizes the use of sample information given this numerical feasibility condition. It is used for estimating a joint participation model of farm couples' farm and off‐farm work. The model yields conclusions about comparative advantages of men and women in farm, off‐farm, and housework, which cannot be obtained with a more limited setup.
Adoption of Emerging Technologies Under Output Uncertainty
Authors: Atanu Saha , Love H. Alan , Schwart Robert
Published: July 2006

A model of divisible technology adoption under incomplete information dissemination and output uncertainty is developed. We identify economic and subjective factors affecting technology adoption and its intensity. Empirical estimation employs a mixed dichotomous‐continuous framework with nonrandom sample selection. Producers' adoption intensity is conditional on their knowing about and deciding to adopt the new technology. Using survey data on bST (bovine somatotropin) adoption among Texas dairy producers, we find that larger and more educated operators are likely to adopt more intensively. Traditional dichotomous adoption models without sample selection significantly overestimate the adoption rate.
Uncoordinated Agricultural and Environmental Policy Making: An Application to Irrigated Agriculture in the West
Authors: Weinberg Marca , Kling Catherine L.
Published: July 2006

Agriculture and the environment are linked by a mutual reliance on scarce resources and prevalent market distortions. In this paper we examine the efficiency costs of policies that correct distortions in one sector while ignoring those in another. The dual distortions of an environmental externality and water subsidies are studied in the context of irrigated agriculture in California. The welfare costs associated with independent action by either a water agency or an environmental authority when that policy maker attempts to correct the respective market distortion without consideration of the distortion in the other market are estimated. Policies to correct the two distortions are found to be complementary. Under these conditions, the independent correction of either distortion improves welfare by at least $@@‐@@118 per acre. In most cases, the simultaneous adoption of various second‐best policies further reduces welfare losses associated with these distortions.
Social Supply and the Evaluation of Food Policies
Authors: Scandizzo Pasquale L. , Knudsen Odin
Published: July 2006

This study develops a model of social supply, based on the hypothesis that society desires that efficient producers remain in business even if their enterprise is too small to withstand the losses caused by extreme price declines. The analysis shows that this concept can be linked to the desire of society of maintaining small producers' income above a minimum level and is consistent with a well‐behaved social welfare function. The study further argues that both social demand and social supply functions may be useful for evaluating policies and projects with socially relevant effects.
Welfare Measurement in Single and Multimarket Models: Theory and Application
Authors: Brännlund Runar , Kriström Bengt
Published: July 2006

In this paper we provide an analysis of tax reforms along the lines of the multimarket welfare measurement techniques suggested by Just, Hueth, and Schmitz. A key purpose of our analysis is to shed light on the approximating features of partial equilibrium models. We derive a result on the difference between single and multimarket welfare measurement, showing how the difference boils down to a set of key parameters. We use our approach to analyze a proposal put forward by the Swedish Commission of Environmental Charges regarding chlorine emissions from the Swedish pulp and paper industry.
Plant Succession as a Natural Range Restoration Factor in Private Livestock Enterprises
Authors: Huffaker Ray , Cooper Kevin
Published: July 2006

We formulate a grazing model linking privately optimal stocking rates to their longterm impacts on the succession of plant species on rangeland. The fast (annual) dynamics of a grazing‐decision component are put in phase with the slow (decadelong) dynamics of a plant‐succession component via the “slow‐manifold” theory of dynamical systems. The model provides the context for analytically approximating “successional thresholds,” partitioning rangeland conditions into those gravitating toward socially desirable or socially undesirable plant compositions over time. These thresholds are instrumental in determining whether grazing management alone can restore rangeland to a socially desired plant composition.
The Impacts of Brand and Generic Advertising on Meat Demand
Authors: Brester Gary W. , Schroeder Ted C.
Published: July 2006

The effects of meat advertising expenditures on quarterly beef, pork, and poultry demand are estimated using a nonlinear Rotterdam model. Advertising stocks are incorporated into the model as both demand shifters and price and total expenditure scaling factors. Branded beef, pork, and poultry advertising elasticities are each significantly different from zero. Generic beef and pork advertising elasticities are not significantly different from zero. Some cross‐advertising elasticities are significantly different from zero. Branded beef and poultry advertising have increased total meat consumption.
Competitiveness of U.S. Food Processing: Benefits from Primary Agriculture
Authors: Gopinath Munisamy , Roe Terry L. , Shane Mathew D.
Published: July 2006

High‐value agricultural products such as processed foods are becoming increasingly important for both the production and trade of the United States. Efficiency gains in primary agriculture may be transferred to the processed food sector in the form of cheaper inputs because price declines and productivity growth have been coincidental in agriculture. In turn, efficiency gains in the processed food sector are transferred, in part, back to primary agriculture by increasing the derived demand and, thus, mitigating the decline in the latter's price. Efficiency gains are relatively more important in primary agriculture than in food processing. Policies which encourage productivity growth that lowers the production costs can increase the competitiveness of both sectors. The ultimate beneficiaries of the price declines in primary agriculture and food processing are consumers.
The Empirical Minimum‐Variance Hedge
Authors: Lence Sergio H. , Hayes Dermot J.
Published: July 2006

Decision making under unknown true parameters (estimation risk) is discussed along with Bayes' and parameter certainty equivalent (PCE) criteria. Bayes' criterion incorporates estimation risk in a manner consistent with expected utility maximization. The PCE method, which is the most commonly used, is not consistent with expected utility maximization. Bayes' criterion is employed to solve for the minimum‐variance hedge ratio. Empirical application of Bayes' minimum‐variance hedge ratio is addressed and illustrated. Simulations show that discrepancies between prior and sample parameters may lead to substantial differences between Bayesian and PCE minimum‐variance hedges.
An Expected‐Indemnity Approach to the Measurement of Moral Hazard in Crop Insurance
Authors: Coble Keith H. , Knight Thomas O. , Pope Rulon D. , Williams Jeffery R.
Published: July 2006

A definition of moral hazard in multiple peril crop insurance is proposed that focuses on expected indemnities rather than input use. Five years of production and insurance data for a panel of Kansas wheat farms is used to empirically test for this type of moral hazard. Results suggest that moral hazard affects multiple peril crop insurance indemnities in poor production years but that no significant moral hazard occurs in years when growing conditions are favorable.
Optimal Marketing of Nursery Crops from Container‐Based Production Systems
Authors: Stokes Jeffrey R. , Mjelde James W. , Hall Charles R.
Published: July 2006

Optimal production and marketing decisions for a nursery producing ornamental plants from a container‐based production system are determined. The stochastic dynamic programming model developed captures the existence of a value‐added, serial‐stage production process with multiple products and intra‐ and interyear dynamics. Results suggest price differentials play an important role in determining the optimal size of plant to market. Further, federal taxes are important for determining the optimal production and marketing decisions while discounting and state taxes play minor roles. Analysis of the transition probability matrices associated with the optimal decisions indicate that the long‐run behavior of the system can be generalized.
Supply Response to Agricultural Insurance: Risk Reduction and Moral Hazard Effects
Authors: Ramaswami Bharat
Published: July 2006

This paper examines the consequences of agricultural insurance for expected supply. The effect of insurance is shown to decompose into a “risk reduction” effect as well as a “moral hazard” effect. The direction and magnitude of these effects depend on the parameters of the insurance contract, producer's risk preferences, and the underlying technology. Two models are considered for this purpose. In the first model, widely employed in the literature, a producer controls only one input. The second model uses a dual approach to extend the results to the case where a producer controls multiple inputs.
Risk Aversion and Yield Uncertainty in Duality Models of Production: A Mean‐Variance Approach
Authors: Coyle Barry T.
Published: July 2006

A duality model of production is developed that endogenizes stochastic output decisions under risk aversion. The model incorporates both yield and price uncertainty and nonlinear mean‐variance risk preferences. This permits modeling of the firm's expected output supply and input demand decisions under risk and also, in principle, the firm's output variance decisions. The duality model is tractable for empirical research.
Rural Wheat Consumption in China
Authors: Carter Colin A. , Zhong Funing
Published: July 2006

The share of wheat in China's overall grain production and consumption has increased since economic reform. China is also a large wheat importer, but imports are erratic. In the literature, there is disagreement over future prospects for per capita wheat consumption in China and imports. Most of the wheat is consumed in rural areas where the majority of the population resides and where consumers have shifted from coarse grains and potatoes to wheat. We analyze rural wheat consumption using household data from two provinces. We find there is evidence to support a contention that China's per capita wheat consumption may not grow very fast in the future and could actually fall.
The Value of El Niño Forecasts in the Management of Salmon: A Stochastic Dynamic Assessment
Authors: Costello Christopher J. , Adams Richard M. , Polasky Stephen
Published: July 2006

The El Niño‐Southern Oscillation (ENSO) is the largest source of interannual variability in global climate. Variability in climate has been linked to variability in fisheries, specifically salmon stocks of the Pacific Northwest. The ability to forecast El Niño events already exists and is likely to improve in coming years. An accurate prediction may have value because it allows for better management decisions. In this article, we develop a bioeconomic model of the coho salmon fishery and derive the value of information from improved El Niño forecasting ability. We find that a perfect El Niño forecast results in an annual welfare gain of approximately $@@‐@@1 million, while imperfect forecasts lead to smaller gains. Results also suggest that optimal management in the face of uncertainty involves a “conservative” management strategy, resulting in lower harvest, higher wild fish escapement, and lower hatchery releases than management in the absence of such uncertainty.
Land Use with Heterogeneous Land Quality: An Application of an Area Base Model
Authors: Hardie Ian W. , Parks Peter J.
Published: July 2006

Area base models are being used in resource assessments to project the availability of farm and forest land. In this paper we introduce a heterogenous land area base model and apply it to a five‐state region in the southeastern United States. Land quality turns out to be an important determinant of land use, suggesting that existing homogeneous land area base models may have an omitted variable problem. Parameter estimates are obtained using a modified multinomial logit model, which allows for error due to the use of county averages and error resulting from the use of sample estimates of land use acreage.
Estimating the Values of Cattle Characteristics Using an Ordered Probit Model
Authors: Sy Hamath A. , Faminow Merle D. , Johnson Gary V. , Crow Gary
Published: July 2006

In this study we evaluate the preferences of cattle producers in Manitoba, Canada, for different cattle characteristics using the conjoint analysis methodology. Preferences are estimated for three different segments of the cattle production system: purebred breeders, commercial cow‐calf producers, and cattle feeders. Data were collected for steers and bulls via a mail survey in 1993. Here we provide relative valuation for the different characteristics by segment of the cattle sector. Evidence is provided that different segments of the cattle sector do not value characteristics the same. For example, purebred breeders have higher preferences for reproduction traits, while feedlot operators give higher values to commercial attributes such as heavy slaughter weight and carcass yield. The different valuations of characteristics across segments of the cattle sector suggest that signals regarding preferences may be noisy. As a result, it might be difficult to design some breed improvement programs to be broadly acceptable, if they have differential benefits to the different segments of producers, when using standard profit‐oriented selection indices.
The Changing Values of the Cooperative and Its Business Focus
Authors: Hind Abigail M.
Published: July 2006

This paper examines the range of objectives open to cooperative businesses and assesses the change in organizational focus over time through the semantic analysis of historical annual reports of seven agricultural cooperative businesses. The findings indicated that, although there was a positive relationship between business age and increasing corporate, as opposed to member, orientation, this phenomenon is not inevitable for all organizations. The results also offered evidence that some of the change in business focus is generated by the internal dynamics of the business rather than from external factors such as competition and economic trends.
Measuring the Importance of Transaction Costs in Cattle Marketing
Authors: Hobbs Jill E.
Published: July 2006

Transaction cost economics recognizes that transactions do not occur in a frictionless economic environment. Information, negotiation, and monitoring costs arise in any transaction and can influence the vertical coordination outcome. This paper demonstrates a method for measuring the influence of transaction costs on slaughter cattle marketing. The paper focuses on the factors affecting the choice between liveweight (live‐ring auction) and deadweight (direct‐to‐packer) sales. Using Tobit limited dependent variable analysis, data from a survey of UK farmers are used to estimate the relative importance of various transaction costs and farm characteristic variables for the choice of marketing channel.
Development of Statistical Discriminant Mathematical Programming Model Via Resampling Estimation Techniques
Authors: Ziari Houshmand A. , Leatham David J. , Ellinger Paul N.
Published: July 2006

This paper uses resampling estimation techniques to develop a statistical mathematical programming model for discriminant analysis problems. Deleted‐d jackknife, deleted‐d bootstrap, and bootstrap procedures are used to identify statistical significant parameter estimates for a discriminant mathematical programming (MP) model. The results of this paper indicate that the resampling approach is a viable model selection technique. Furthermore, estimating the MP models via resampling techniques can also improve the classification performance compared to a deterministic discriminant MP model. In this study, the deleted‐d jackknife procedure was the most promising among the resampling estimation techniques examined.
A Dynamic Analysis of Land Prices
Authors: Chavas Jean‐Paul , Thomas Alban
Published: July 2006

A dynamic model of land prices is developed. It derives arbitrage asset prices under nonadditive dynamic preferences, risk aversion, and transaction costs. The model nests as special cases risk neutrality, time‐additive preferences, the static capital asset pricing model (CAPM), as well as the dynamic consumption‐based CAPM. The model is applied to the analysis of U.S. land prices for the period 1950–96. The econometric results provide evidence showing that U.S. land price patterns are inconsistent with risk neutrality or with the static CAPM model. No strong evidence was found against time‐additive preferences. The econometric findings indicate that both risk aversion and transaction costs have significant effects on land prices.
Damage Control and Increasing Returns: Further Results
Authors: Hennessy David A.
Published: July 2006

Recently, researchers have been paying attention to the possibility of increasing returns to the use of damage control inputs under very plausible technologies. By looking at the mathematical structure of damage and control functions, we can describe a necessary and sufficient condition on these functions for locally increasing returns to occur. Using examples, I demonstrate how the result can be applied to models with single or multiple control inputs. Because analytic solutions are sometimes not possible, a simple empirical test for concavity violations is also provided. A caution is given about problems associated with estimating the basic model specification.
Optimum Area Yield Crop Insurance
Authors: Mahul Olivier
Published: July 2006

This article considers the problem of the optimal design of crop insurance when the indemnity is based upon the aggregate yield of a surrounding area. The optimal area yield crop insurance contract depends on the individual beta coefficient which measures the sensitivity of farm yield to area yield. Indemnity payments are made whenever the realized area yield is lower (higher) than a critical yield if the beta coefficient is positive (negative). The optimal contract contains a “disappearing deductible” if the beta coefficient is higher than unity.
Farm Growth and Survival: Econometric Evidence for Individual Farms in Upper Austria
Authors: Weiss Christoph R.
Published: July 2006

This article investigates survival and growth of more than 50,000 Upper Austrian farm households within a maximum likelihood sample selection framework. The results suggest that age, schooling and sex of the farm operator, size of the farm family, and off‐farm employment status, as well as initial farm size, significantly influence farm growth and survival. The present study provides support for the notion of a “disappearing middle” in the size distribution. The process of polarization is closely related to the off‐farm employment status of farms. Correcting for sample‐attrition bias is important when analyzing the performance of part‐time farms.
Compensating for Information Externalities in Technology Diffusion Models
Authors: Shampine Allan
Published: July 2006

The role of information in the adoption of new technologies is discussed, focusing on the role of information externalities when nonadopters observe adopters in order to gather information. A Bayesian model of aggregate adoption is derived and the social planner's relationship to the model is discussed. The fact that the information externality is uncompensated suggests that too little adoption may occur. The social planner's problem is solved numerically, demonstrating rapid learning on the part of adopters and a limited ability for the social planner to compensate for the information externality.
The Contribution of Genetic Resources and Diversity to Wheat Production in the Punjab of Pakistan
Authors: Smale Melinda , Hartell Jason , Heisey Paul W. , Senauer Ben
Published: July 2006

Recent criticisms of the “green revolution” wheats concern the effects of their popularity on crop diversity and the consequences for productivity and conservation. We use a Just‐Pope production function to test the relationship of genetic resource and diversity variables to mean and variance of wheat yields in the Punjab of Pakistan. In irrigated areas, greater area concentration among varieties is associated with higher mean yields. In rainfed districts, genealogical variables are associated positively with mean yield and negatively with yield variance. Further research is needed to overcome data limitations, capture biological relationships more accurately, and specify a fuller decision‐making model.
The Choice of Tillage, Rotation, and Soil Testing Practices: Economic and Environmental Implications
Authors: Wu JunJie , Babcock Bruce A.
Published: July 2006

Farmers' management practices can have a significant effect on agricultural pollution. Past research has analyzed factors influencing adoption of a single management practice. But often adoption decisions about many practices are made simultaneously, which suggests use of a polychotomous‐choice model to analyze decisions. Such a model is applied to the choice of alternative management practices on cropland in the Central Nebraska Basin and controlled for self‐selection and the interaction between alternative practices. The results of the choice model are used to estimate the economic and environmental effects of adopting alternative combinations of management practices.
The Effect of Rental Rates on the Extension of Conservation Reserve Program Contracts
Authors: Cooper Joseph C. , Osborn C. Tim
Published: July 2006

Given that the majority of conservation reserve program (CRP) contracts on approximately 36 million acres of enrolled land expire concurrently, re‐enrollment decisions by farmers and the federal government have high budgetary implications. Using a survey of over 8,000 CRP contract holders, we apply an ordered response discrete choice model to explicitly model the range in rental rates over which the representative farmer may be ambivalent to renewing the CRP contract. Given the empirical results from the ordered response model, we estimate acreage re‐enrollment as a function of the rental rate and compare them to results of a binomial choice model.
Relationship between One‐Electron Transition‐Metal Reactivity and Radical Polymerization Processes
Authors: Poli Rinaldo
Published: July 2006

Controlled radical polymerization has come along in leaps and bounds following the development of efficient transition‐metal catalysts for atom‐transfer radical polymerization. Another type of controlled radical polymerization process, namely organometallic radical polymerization, uses the reversible formation of metal–carbon bonds. Metals are also implicated in catalytic chain transfer, a process that involves the abstraction of hydrogen atoms. This Minireview discusses the importance of one‐electron transition‐metal reactivity in metal‐mediated controlled radical polymerization processes.
Nucleophilic Activation of Alkenyl and Aryl Boronates by a Chiral CuIF Complex: Catalytic Enantioselective Alkenylation and Arylation of Aldehydes
Authors: Tomita Daisuke , Kanai Motomu , Shibasaki Masakatsu
Published: July 2006

A new method for the catalytic enantioselective alkenylation and arylation of aldehydes involves the activation of alkenyl and aryl boronates by a catalytic amount of the CuIF–DTBM‐segphos complex through transmetalation, generating novel alkenyl and aryl copper species. These reagents act as the actual nucleophile. A range of aldehydes can be converted into optically active secondary allyl alcohols or diaryl methanols with excellent enantioselectivity. The appropriate choice of additives, depending on the substrate, is critical to ensure high yields of products. These additives possibly modulate the catalyst turnover step from copper alkoxide intermediates generated by the addition of organocopper reagents to aldehydes.
Polymerization in Coordination Nanospaces
Authors: Uemura Takashi , Horike Satoshi , Kitagawa Susumu
Published: July 2006

Inspired by elegant polymerizations in biological systems, polymer synthesis in confined artificial nanospaces is a key challenge in the control of polymer structures and the design of well‐defined nanostructures. In this regard, porous coordination polymers (PCPs) have a wide range of advantages, such as regular channel structures, controllable pore size, dynamic and flexible pores, and unique surface potentials and functionality, which can be utilized for precisely controlled polymerization and polymer arrangement. This Focus Review describes recent progress in polymerization in the nanochannels of PCPs and demonstrates why this polymerization system is so attractive and promising, from the viewpoints of three essential polymerization processes in PCPs, that is, monomer arrangement, polymerization methods, and control of polymer structure.
Endovascular stents for relief of cyanosis in single‐ventricle patients with shunt or conduit‐dependent pulmonary blood flow
Authors: Petit Christopher J. , Gillespie Matthew J. , Kreutzer Jacqueline , Rome Jonathan J.
Published: July 2006

Hypoxemia is a significant cause of early and interstage death in patients with single ventricle (SV). Obstruction of Blalock‐Taussig shunts (BTS) in patients with SV has traditionally been managed with surgical revision. Purpose: We report on the experience at our institution of deploying endovascular stents within BTS as well as obstructed right‐ventricle (RV) to pulmonary artery (PA) conduits in patients with modified Norwood (ie Sano modification). Methods: Medical records were reviewed for the time period between January 1, 2002 and November 30, 2005. All patients with SV who presented for intervention for BTS or RV‐PA conduit stenosis were reviewed. Specific endpoints reviewed included pre‐ and post‐intervention arterial oxygen saturation, type of intervention (stent vs. ballon dilation), need for subsequent surgical shunt/conduit revision, and interval to second stage palliation. Results: Fifteen patients with SV underwent intervention for acute cyanosis. Eight patients had BTS, and the other seven patients had RV‐PA conduit stenosis. Coronary stents were deployed in 14 of the 15 patients. Four patients also underwent balloon angioplasty of branch PAs. Oxygen saturations improved in all patients, with a mean increase of 13.9% (p = 0.0001). Four patients died before second stage palliation — one due to complications of the catheterization. Of the eleven remaining patients, nine have undergone second stage palliation; interval from intervention to Glenn ranged from 28–205 days (mean 163d). Two patients are awaiting cavo‐pulmonary anastamosis. Conclusions: Endovascular stenting in this high‐risk population is effective at improving oxygen saturation as well as obviating need to surgical shunt/conduit revision. © 2006 Wiley‐Liss, Inc.
Double Perovskites as Anode Materials for Solid‐Oxide Fuel Cells.
Authors: Huang Yun‐Hui , Dass Ronald I. , Xing Zheng‐Liang , Goodenough John B.
Published: July 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Nonlocal Magnetization Dynamics in Ferromagnetic Heterostructures
Authors: Tserkovnyak Yaroslav , Brataas Arne , Bauer Gerrit E. W. , Halperin Bertrand I.
Published: July 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthesis, anti‐HIV and Antitubercular Activities of Isatin Derivatives.
Authors: Sriram D. , Yogeeswari P. , Meena K.
Published: July 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Antiferromagnetism in LiCoPO4 and LiNiPO4
Authors: Vaknin David , Zarestky Jerel L. , Rivera Jean‐Pierre , Schmid Hans
Published: July 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Fast Time Scale Dynamics of Protein Backbones: NMR Relaxation Methods, Applications, and Functional Consequences
Authors: Jarymowycz Virginia A. , Stone Martin J.
Published: July 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
2‐Arylthienyl‐Substituted 1,3‐Benzothiazoles as New Nonlinear Optical Chromophores
Authors: Costa Susana P. G. , Batista Rosa M. F. , Cardoso Paulo , Belsley Michael , Raposo Maria Manuela M.
Published: July 2006

A series of nonlinear optical chromophores6containing a substituted benzothiazole ring have been synthesized and characterized. 1,3‐Benzothiazoles6were prepared by treating various formyl derivatives of thienyl compounds withortho‐aminobenzenethiol in fair to excellent yields. These in turn were prepared by Suzuki coupling between aryl and thienyl precursors. The electronic interactions between donor and acceptor end groups in the conjugated 1,3‐benzothiazoles6are revealed by the intense and markedly solvatochromic CT transitions. The solvatochromic behaviour of compounds6was determined by linear regression analyses of absorption maxima in several solvents, where benzothiazole6fwas found to be a very appropriate indicator dye whose absorption wavenumbers (Δ$\tilde {\nu}$max= 1590 cm–1) in aliphatic and dipolar aprotic and in aromatic and chlorinated solvents correlated excellently with the π* values defined by Kamlet and Taft. Hyper‐Rayleigh scattering was used to measure the first hyperpolarizabilitiesβof the aforementioned compounds. Thermogravimetric analysis (TGA) was used to evaluate their thermal stability. The experimental results indicate that good nonlinearity and thermal stability are well balanced for chromophores6, making them good candidates for device applications. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthesis of α‐Aryl‐Substituted and Conformationally Restricted Fosmidomycin Analogues as Promising Antimalarials
Authors: Haemers Timothy , Wiesner Jochen , Busson Roger , Jomaa Hassan , Van Calenbergh Serge
Published: July 2006

Fosmidomycin represents a new antimalarial drug that acts by inhibition of 1‐deoxy‐D‐xylulose 5‐phosphate reductoisomerase, an essential enzyme of the mevalonate‐independent pathway of isoprenoid biosynthesis. This work describes the synthesis of a series of α‐aryl‐substituted fosmidomycin analogues that exhibit improved antimalarial activity. A linear synthetic route involving a 3‐aryl‐3‐phosphorylpropanal intermediate proved practical to prepare these derivatives. A phospha‐Michael addition to cyclopent‐2‐enone gave access to conformationally restricted analogues. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Induction of astrocyte differentiation by propentofylline increases glutamate transporter expression in vitro: Heterogeneity of the quiescent phenotype
Authors: Tawfik Vivianne L. , Lacroix‐Fralish Michael L. , Bercury Kathryn K. , Nutile‐Mcmenemy Nancy , Harris Brent T. , Deleo Joyce A.
Published: July 2006

Reactive astrocytes display decreased glutamate transporters, such as GLT‐1, and as a result synaptic glutamate clearance is impaired. In addition, these activated astrocytes are immunocompetent and release algesic mediators that can sensitize neurons in the spinal cord. Currently, we evaluated the effect of propentofylline (PPF), an experimental antiallodynic agent, on the phenotype and glutamate transporter expression of astrocytes. Primary astrocyte cultures, which represent an activated phenotype with a polygonal morphology and low GLT‐1 expression, were treated for 3 or 7 days with 10, 100, or 1,000 μM PPF or dibutyryl‐cAMP (db‐cAMP), a known inducer of GLT‐1 expression. PPF dose‐dependently induced astrocytes to display a mature phenotype, with elongated processes and a stellate shape, as well as increased GLT‐1 and GLAST immunoreactivity, similar to that seen with db‐cAMP. Real time RT‐PCR and Western blot analysis clearly demonstrated that PPF caused a potent dose‐dependent induction of GLT‐1 and GLAST mRNA and protein in these astrocytes. Importantly, the observed increase in glutamate transporters was found to have a functional effect, with significantly enhanced glutamate uptake in astrocytes treated with 100 or 1,000 μM PPF that was sensitive to dihydrokainate inhibition, suggesting it is GLT‐1 mediated. Finally, the effect of PPF on lipopolysaccaride‐induced chemokine release was investigated. Interestingly, PPF was able to dampen both MCP‐1 (CCL2) and MIP‐2 (CXCL2) release from astrocytes while db‐cAMP significantly enhanced this chemokine expression. These findings suggest that PPF is capable of differentiating astrocytes to a homeostatic, mature phenotype, competent for glutamate clearance and distinct from that induced by db‐cAMP. © 2006 Wiley‐Liss, Inc.
Spin‐dependent dynamics of ultrafast polarised optical pulse propagation in coherent semiconductor quantum systems
Authors: Slavcheva G. , Hess O.
Published: July 2006

A new model for rigorous theoretical description of circularly (elliptically) polarised ultrashort optical pulse interactions with the resonant nonlinearities in semiconductor optical waveguides is proposed. The method is based on self‐consistent solution in the time domain of the vector Maxwell equations coupled via microscopic polarisation to the coherent time‐evolution equations of a discrete N‐level quantum system in terms of the real pseudospin (coherence) vector. The model is initially applied to a generic two‐level quantum system and subsequently to a 4‐level system describing the heavy‐hole excitonic transitions in low‐dimensional semiconductor systems, such as quantum wells and quantum dots. Selective optical excitation of specific spin states by predefined helicity of the optical field in the linear regime and an onset of self‐induced transparency and polarised soliton formation in the nonlinear regime are numerically demonstrated in both discrete‐level systems. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiplicative background correction for spotted microarrays to improve reproducibility
Authors: ZHANG DABAO , ZHANG MIN , WELLS MARTIN T.
Published: July 2006

We propose a simple approach, the multiplicative background correction, to solve a perplexing problem in spotted microarray data analysis: correcting the foreground intensities for the background noise, especially for spots with genes that are weakly expressed or not at all. The conventional approach, the additive background correction, directly subtracts the background intensities from foreground intensities. When the foreground intensities marginally dominate the background intensities, the additive background correction provides unreliable estimates of the differential gene expression levels and usually presents M–A plots with ‘fishtails’ or fans. Unreliable additive background correction makes it preferable to ignore the background noise, which may increase the number of false positives. Based on the more realistic multiplicative assumption instead of the conventional additive assumption, we propose to logarithmically transform the intensity readings before the background correction, with the logarithmic transformation symmetrizing the skewed intensity readings. This approach not only precludes the ‘fishtails’ and fans in the M–A plots, but provides highly reproducible background-corrected intensities for both strongly and weakly expressed genes. The superiority of the multiplicative background correction to the additive one as well as the no background correction is justified by publicly available self-hybridization datasets.
State Sector Reform and Agriculture in China
Authors: Waldron Scott , Brown Colin , Longworth John
Published: July 2006

China's state sector reform process is examined through the key sector of agriculture. A preview of aggregate statistics and broader reform measures indicate the declining role of the state. However, a systematic analysis of administrative, service and enterprise structures reveal the nuances of how the state has retained strong capacity to guide development of the agricultural sector. State and Party policy makers aim not only to support the livelihoods of hundreds of millions of farmers, but also to pursue agricultural modernization in the context of rapid industrialization. These goals are unlikely to be achieved through a wholesale transfer of functions to the private sector, so the state has maintained or developed new mechanisms of influence, particularly in the areas of service provision and enterprise development.
Low vowels and transparency in Kinande vowel harmony
Authors: Gick Bryan , Pulleyblank Douglas , Campbell Fiona , Mutaka Ngessimo
Published: July 2006

This paper addresses theoretical issues confronting cross-height harmony systems through an experimental study of Kinande, a Bantu language of the Democratic Republic of Congo. Using a combination of acoustic analysis and lingual ultrasound imaging, we evaluate previous proposals concerning the phonetic correlates of the harmonic vowel feature and the transparency of low vowels. Results indicate that (i) although a multivalued scalar acoustic feature in F1/F2 space is not adequate to distinguish all vowel categories in Kinande, the cross-height feature does correlate acoustically with F1, (ii) the cross-height feature of Kinande involves systematic tongue-root articulations and (iii) low vowels in Kinande are not neutral to harmony in the way reported in earlier work, but exhibit significant and systematic tongue-root advancement and retraction according to the dictates of harmony.
Relations among quantum processes: bisimilarity and congruence
Authors: LALIRE MARIE
Published: July 2006

Full formal descriptions of algorithms making use of quantum principles must take into account both quantum and classical computing components, as well as communications between these components. Moreover, to model concurrent and distributed quantum computations and quantum communication protocols, communications over quantum channels that move qubits physically from one place to another must also be taken into account.

Inspired by classical process algebras, which provide a framework for modelling cooperating computations, a process algebraic notation is defined. This notation provides a homogeneous style for formal descriptions of concurrent and distributed computations comprising both quantum and classical parts. Based upon an operational semantics that makes sure that quantum objects, operations and communications operate according to the postulates of quantum mechanics, an equivalence is defined among process states considered as having the same behaviour. This equivalence is a probabilistic branching bisimulation. From this relation, an equivalence on processes is defined. However, it is not a congruence because it is not preserved by parallel composition.
Historical institutional analysis of social-ecological systems
Authors: JANSSEN MARCO A.
Published: July 2006

Institutions, the rules that govern interactions between people, evolve over time. This special issue presents a number of detailed case studies of human–environment interactions during a significant historical period. With social-ecological systems we mean a set of people, their natural and human-made resources, and the relationships among them (Anderies et al., 2004, Janssen et al., 2005).
Isolation and Characterization of Root‐Specific Phosphate Transporter Promoters from Medicago truncatula
Authors: Xiao K. , Liu J. , Dewbre G. , Harrison M. , Wang Z.‐Y.
Published: July 2006

Abstract: Promoters of phosphate transporter genes MtPT1 and MtPT2 of Medicago truncatula were isolated by utilizing the gene‐space sequence information and by screening of a genomic library, respectively. Two reporter genes, β‐glucuronidase (GUS) and green fluorescent protein (GFP) were placed under the control of the MtPT1 and MtPT2 promoters. These chimeric transgenes were introduced into Arabidopsis thaliana and transgenic roots of M. truncatula, and expression patterns of the reporter genes were assayed in plants grown under different phosphate (Pi) concentrations. The expression of GUS and GFP was only observed in root tissues, and the levels of expression decreased with increasing concentrations of Pi. GUS activities in roots of transgenic plants decreased 10‐fold when the plants were transferred from 10 μM to 2 mM Pi conditions, however, when the plants were transferred back to 10 μM Pi conditions, GUS expression reversed back to the original level. The two promoters lead to different expression patterns inside root tissues. The MtPT1 promoter leads to preferential expression in root epidermal and cortex cells, while MtPT2 promoter results in strong expression in the vascular cylinder in the center of roots. Promoter deletion analyses revealed possible sequences involved in root specificity and Pi responsiveness. The promoters are valuable tools for defined engineering of plants, particularly for root‐specific expression of transgenes.
Karyotype Studies in South American Species of Solanum subgen. Leptostemonum (Solanaceae)
Authors: Chiarini F. , Bernardello G.
Published: July 2006

Abstract: Mitotic chromosome numbers and karyotypes of 13 South American species (12 native and one naturalized) from four sections of Solanum subgen. Leptostemonum were studied. Chromosome numbers of S. acerifolium, S. aenictum, S. conditum, S. consimile, S. incarceratum, and S. platense are reported for the first time. The number 2n = 24 was found in most species, while 2n = 22 was found in S. mammosum and S. platense. The latter is the second Solanum with this unusual number. Satellites are always present and were visible in more than 50 % of the cells studied. Karyotypes are symmetrical: m and sm chromosomes are common, whereas st chromosomes are rare. The karyotypes of S. aenictum, S. mammosum, and S. paniculatum are comparatively asymmetrical. Species can be distinguished by a combination of chromosome number, karyotype formulae, karyotype length, the position of satellites in a particular chromosome pair, and asymmetry indices. The phenogram obtained does not reflect the sectional arrangements or the systematic affinities of the species studied. In sect. Acanthophora, increased asymmetry is associated with derived characters (strong andromonoecy, winged seeds, mammiform fruits). Diversification in the subgenus is suggested to be related to visible chromosome rearrangements and cumulative, cryptic structural changes may have also played a relevant evolutionary role.
Development of NaCl‐Tolerant Strain in Chrysanthemum morifolium Ramat. through in vitro Mutagenesis
Authors: Hossain Z. , Mandal A. K. A. , Datta S. K. , Biswas A. K.
Published: July 2006

Abstract: One NaCl‐tolerant chrysanthemum (Chrysanthemum morifolium Ramat.) variant (E2) has been developed in a stable form through in vitro mutagenesis using ethylmethane sulfonate (EMS) as the chemical mutagen. Salt tolerance was evaluated by the capacity of the plant to maintain both flower quality and yield under stress conditions. Enhanced tolerance of the E2 variant has been attributed to the increased activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), and dehydroascorbate reductase (DHAR), and, to a lesser extent of membrane damage than NaCl‐treated control plants. Isoform analysis revealed that an increase in total SOD activity in the E2 variant was solely due to significant activation of the Cu/Zn isoform. Elevated levels of carotenoids and ascorbate in E2 leaves have been reflected in their higher free radical scavenging capacity (RSC) expressed in terms of DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) scavenging ability. Data reflect that a proper balance between enzymatic and non‐enzymatic defence systems is required for combating salinity stress in chrysanthemum. Better performance of the E2 progeny under same salinity stress condition, even in the second year, confirms the genetic stability of the salt‐tolerance character. On the whole, the E2 variant, developed through 0.025 % EMS treatment, might be considered as a NaCl‐tolerant strain showing positive characters towards NaCl stress.
Hospice and the Spatial Paradoxes of Terminal Care
Authors: Brown Michael
Published: July 2006

The purpose of my paper is to offer an understanding of home hospice from a perspective of political geography. Informed by critical political theories of care, and recent work on the geographies of public and private spheres, I explore one set of consequences of the spatial shift towards home death in metropolitan Seattle, Washington. Terminal hospice care done in the home creates an especially paradoxical home space. By blurring public–private boundaries, hospice care produces a political geography of home interpretable through four spatial paradoxes: a normative paradox of home being a good and bad place to die, a territorial paradox of control itself changing the home, a constitutive paradox between heart and welfare politics, and a relational paradox between autonomy and dependency. The implications for political and health geography, as well as political theory and hospice work itself are discussed as a consequence of recognizing these spatial paradoxes.
Modelling a Single Type of Environmental Impact from an Obnoxious Transport Activity: Implementing Locational Analysis with GIS
Authors: Moreno-Jiménez Antonio , Hodgart Robert Lindsay
Published: July 2006

Many facilities have negative impacts on neighbouring areas, and an obvious social and political concern is therefore to assess and minimise such impacts. The authors address this type of problem in relation to the dispersion of aircraft noise near airports. The approach involved brings together two basic components. First, two spatial models are presented. These are developed from existing concepts in location theory and modelling, but the authors attempt to overcome some of the limitations of previous models. Second, a geographical information system is used to obtain a better representation of the spatiotemporal processes involved in the dispersion of aircraft noise and to evaluate the functions of the two models. A case study is used to illustrate the methodology and helps to indicate how this approach could facilitate improved spatial decisionmaking.